Results:

This document details the objectives, cost, duration, and summary of the research carried out by the Department of Trade and Industry into NOx reduction using overfire air staging. This work extends previous high temperature wire mesh (HTWM) studies at ICSTM, including two previous DTI projects, examining the relationship between NOx from aerodynamically air staged low NOx burners, principally Mitsui Babcock MkIII, and char nitrogen. With aerodynamic air staging alone, however, higher apparent char N conversions and additional NOx contributions from thermal and possibly other sources were observed and data from a number of different plants had to be used to cover a similar range of coals. The work proposed provides a basis for the application of a new standard test that is pertinent to pulverised coal combustion, and addresses the research and development priority areas identified by the Foresight Task Force including the impact of coal quality on turndown, burnout and NOx formation and the acquisition of data on and modelling of combustion performance of coals.

The overall project objective is to make available generic coal information on Chinese and Indian coals with regard to their combustion and emission performance, and to establish correlations between basic properties and this performance. Such information is clearly of value to UK industry in view of the export possibilities in these regions.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

The aim of the advanced coal combustion modelling project is to develop and validate an improved combustion model for predicting the combustion efficiency in pf fired utility boilers. The model techniques will be able to:

Predict carbon burnout in new boiler and firing system designs

Identify the impact of different coals on existing boiler and firing system designs

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

The principle aim of the University of Leeds 'Advanced Coal Combustion Modelling Project' is to deliver a more fundamental model of carbon burnout with the objective of increasing the accuracy of these models. The project consists of the following stages:

Develop a model to estimate the amount of char produced during devolatilisation.

Develop a char burnout model using the estimation of the amount of char produced in the devolatilisation step.

Incorporate the results into an overall char burning model suitable for combustion in a drop tube or a simplified power station combustor.

This project summary contains information on:

Objectives

Summary

Introduction

The development of computer models

Application to test cases

Cost

Duration

Collaborators

This document is a profile for the project titled 'Advanced Materials Modelling And Lifing Technologies For Gas Turbine Components Operating In Coal Gasification Plant'.

Over the next decade all major gas turbine manufacturers will, be aiming to achieve higher efficiencies and lower emissions from turbine technology regardless of the fuel type used. For coal-fired plant the challenges are not only to match the performance of natural gas fired turbines, but also to meet the technical challenge brought about by the use of aggressive fuel gas. By conducting a programme of work in three key technological areas - advanced materials, materials modelling and lifing methodologies - this programme aims:

To improve quantifiably the performance of industrial gas turbines operating in coal-fired power plant.

To provide spin off benefits to gas turbines operating with a wide range of other fuels including biomass, waste and natural gas.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

This document is a profile for the project titled 'Advanced Modelling And Testing Of Thick Section Welded Hcm2s'.

The principal aim of the project is to use advanced modelling and testing to extend the size range in which the HCM2S steel can be fabricated with and without post weld heat treatment (PWHT). The specific objectives of the project are:

To optimise the fabrication of thick section HCM2S utilising practical and efficient welding processes (MMA,FCAW).

To investigate thoroughly the welding of HCM2S without PWHT.

To model the weld and cross-weld mechanical properties of HCM2S with, and without, PWHT.

To demonstrate acceptable weldment mechanical properties.

To produce fabrication guidelines for thick section HCM2S with, and without, PWHT.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

This document is a report for the project titled 'Advanced Modelling and Testing – Thick Sectioned Welded Alloy HCM2S (P23)'.

The principal aim of the project was to use advanced modelling and testing to extend the size range for which the HCM2S (P23) steel can be fabricated both with and without PWHT. The specific objectives were:

• To optimise the fabrication of thick section HCM2S utilising practical and efficient welding processes (MMA, FCAW).
• To thoroughly investigate the welding of HCM2S without PWHT.
• To model the weld and cross weld mechanical properties of HCM2S both with and without PWHT in order to define cross weld properties.
• To demonstrate acceptable weldment mechanical properties.
• Consequently to produce fabrication guidelines for thick section HCM2S both with and without PWHT.

This report is divided into the following sections:

1. Background
2. Welding & Weld procedure qualification
3. Neural network analysis
4. Service Aged Material
5. Stress Rupture Testing
6. Residual Stress Modelling
7. General Discussion & Conclusions

This document is a profile for the project titled 'Advanced Monitoring Using Imaging For Combustion In Power Station Boilers'.

Recent improvements in self illuminating video (SIV) imaging equipment and digital image processing together with the falling costs of the necessary hardware, mean that there is the potential to develop commercially viable systems to generate quantifiable performance parameters from boiler video cameras. This information can then be used for combustion improvements on utility boilers. This programme aims to develop a prototype SIV system and test it in real environments in order to achieve the following objectives:

To use SIV and image analysis techniques to identify adverse combustion conditions.

To provide a number of quantifiable parameters from video images which can be used to evaluate flame stability and combustion.

To develop software to run on a stand-alone PC system to provide the above information in real-time and transfer key parameters to existing data logging systems.

To develop systems to transmit and integrate video data from a number of cameras under actual boiler conditions.

To determine optimum video probe designs and locations for quantitative SIV.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

This document is a profile for the project titled 'Advanced Near Burner Flame Diagnostics For Ignition And Stability Studies On Full Scale Pulverised Coal Flames'.

The overall aim of the project is to improve the simulation of the near burner region of flames by CFD models, and to devise techniques whereby ignition processes in the vicinity of the flame holder and the flame structure immediately downstream can be assessed for individual flames in large pulverised coal fired furnaces. Specific project objectives are:

To establish a technique whereby the near burner region, and in particular the ignition regions of the flame, can be observed and recorded by means of a high-speed video probe.

To demonstrate this technique in plant trials, using existing test activities to assess factors such as the impact of local operating conditions and coal quality on burner stability and near-burner flame structures.

To assess the capability of existing CFD codes to simulate the observed processes occurring in the near burner region (with specialised laboratory coal testing at ICSTM to assess coal properties).

To investigate the potential differences between single burner and multi-burner furnace performance.

To increase the level of confidence in the use of CFD modelling for the simulation of burners and furnaces.

To develop the equipment and processing methods for industrial use as a specialised diagnostic technique to assist in plant optimisation of individual burners in a multi-burner furnace or in recording the localised flame structures in the near burner region to aid in the development of improved burner designs.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

This document is a report for the project titled 'Advanced Optimisation - Coal Fired Power Plant Operations'.

In recent years the efforts to reduce nitrogen oxide (NOx) emissions from power stations have resulted in operational modifications including the fitting of low - NOx burners. These modifications are expensive and generally have an adverse effect upon plant performance, resulting in an increase in unburnt carbon. To reduce these adverse effects, on-line optimisers have been developed as an enhancement to the power station's digital control system (DCS). GNOCIS (Generic NOx Optimisation Control Intelligent System) is the main optimiser used within the UK. This is a neural network based optimiser that takes various control parameters such as mill feeder speeds, excess oxygen, burner tilt and load as inputs and predicts the resultant NOx emissions and carbon-in-ash levels. In fact the models are usually used in reverse with boiler control settings being provided by the model to optimise the emissions.

The success of the boiler optimisation models has suggested that on-line optimisation can be used in other parts of the power station, eg thermal efficiency, electrostatic precipitator (ESP). Although each local optimiser is able to perform its task well individually there will be occasions when the individual packages will provide conflicting advice. The purpose of this unit optimisation project is to develop an integrated approach to unit optimisation and develop an overall optimiser that is able to resolve any conflicts between the individual optimisers.

This report is divided into the following sections:

1. Introduction
2. Project Members
3. Individual Optimisers
4. On-Line Thermal Efficiency Package
5. GNOCIS/Boiler
6. GNOCIS/Turbine
7. ESP Optimisation
8. Intelligent Sootblowing System (ISBS)
9. Unit Optimiser
10. Software Implementation
11. Handling Conflict Among Optimisers
12. On-Line Power Plant Optimisers in the UK
13. Recommendations
14. Conclusions
15. References

This document is a report for the project titled 'Advanced PF Power Plant - Improved Materials for Boilers and Steam Turbines'.

In 1997 the Foresight Task Force identified advanced pulverised fuel technology as having the greatest market potential of the Clean Coal Technologies over the following 15 years. This task force, together with the Institute of Materials task force on materials, highlighted that the economic and environmental performance of this technology was currently limited by the performance of high temperature materials for boilers and steam turbines. As a consequence of this, the required R&D programmes perceived as being necessary for the development of improved materials were outlined.

This programme is receiving support through the EC's Thermie framework and from the DTI. It has a far longer timescale to fruition than the present initiative, as it will require inclusion of a demonstration phase. The technology involved in the present programme will be commercially exploitable much earlier, and, even after introduction of technology based on nickel based alloys, it will continue to be competitive in markets particularly sensitive to capital cost rather than through-life cost. The present programme is implemented through a wider European collaboration under the auspices of COST 522; as such collaboration reduces the costs of implementation and ensures that the UK remains abreast of the state-of-the-art in this technology.

This report is divided into the following sections:

1. Background
2. The Cost Framework of Programmes
3. Technical and Economic Value
4. Boiler Group Activities
5. Steam Turbine Group Activities
6. Common Activity Goals
7. Plant Integration and Ancillary Components Group
8. Conclusions
9. Acknowledgements
10. References
11. Abbreviations Used in Text

This document is a profile for the project titled 'Improved Materials for Boilers and Steam Turbines'.

The principal aim of this project was to develop and demonstrate the suitability of advanced materials and components for the power industry. Such materials and components were aimed at steam temperatures of 620 - 650°C. Specific areas covered were:

Development and assessment of improved alloys for boiler superheaters, headers, pipework and furnace walls.

Development of improved alloys for steam turbine high temperature rotor forgings, castings, and bolting. Prototype component manufacture and characterisation.

Development and modelling of welding procedures and consumables for the above groups.

Accelerated alloy development and application through improved understanding and modelling of microstructural evolution and its relationship to mechanical properties.

Characterisation of steam oxidation behaviour of new alloys, and modelling of spallation.

This summary contains information on the project's:

Objectives

Summary

Summary

Background

Experimental Work

Results

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

This document is a summary of the project titled 'With/without CO2 Capture Options'.

The aim of the project is to evaluate the technical and economic feasibility of retrofitting UK coal-fired power plants with advanced supercritical boiler/turbine technology (ASC) and carbon dioxide capture. The specific objectives are:

To establish optimum retrofit solutions for a reference power plant typical of the majority of UK coal fleet (500MWe and larger).

To determine the relative benefits of alternative approaches to the possible staging of retrofits for the short-term or the long-term.

To review the applicability of the optimum retrofit solutions for a range of UK power plant sites and to indicate the variances arising due to site conditions.

This summary contains information on the project's:

Objectives

Summary

Cost

Duration

Lead Contractor

Collaborators

Sponsors

This document is a report that summarises the findings of the DTI Cleaner Coal Technology R and D Programme Project 217 'Application of CFD Modelling to Mill Classifier Design'.

In order to reduce the carbon in ash (CIA) levels arising from the application of advanced low NOX technologies, it is necessary to improve the quality and consistency of the coal milling process. In many low NOX retrofit applications, mill upgrades, including classifier upgrades, are required to achieve the improved milling performance. Unfortunately, plant space constraints often make it impossible to install classifiers of ideal geometries and the performance of non-ideal geometries is difficult to predict using existing design methods. In addition, low quality coals are increasingly being used, alone or in blends, to reduce plant operating costs. The grinding and classification behaviour of low quality coals and their blends has been found to differ from that of UK and world-traded bituminous coals. Consequently, classifier design rules that have been derived from the extensive experience of milling bituminous coals are less reliable when applied to low quality coals. There is a clear requirement to improve and extend the range of applicability of classifier design methods so that they may be used to design classifiers of non-ideal geometries and for coals outside the conventional range of experience.

This report is divided into the following sections:

1. Introduction
2. Classifier Design
3. Review of E Mill Classifier Process Data and Design Rules
4. Physical Model Testing
5. CFD Simulation of Physical Model
6. Plant Trials
7. CFD Simulation of E Mill Classifiers
8. Development of Improved Design Rules
9. CFD Simulation of Primary Classification
10. Conclusions
11. Recommendations for Further Work
12. Acknowledgements

This document is a profile for the project titled 'Impact on Plant Performance and Ash Disposal'.

This proposal aims to provide coal-fired power stations with a simple, cost effective, means of improving combustion efficiency and reducing particulate emissions by re-firing ash and/or mineral addition to the coal. This project will:

Generate guidelines and identify constraints for re-firing pulverised fuel ash (PFA) and mineral addition.

Test ash re-firing at pilot scale and then at full scale.

Test mineral addition using an Entrained Flow Reactor.

Perform a techno-economic assessment of ash re-firing and mineral addition.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

Collaborators

This document is a summary for the project titled 'Impact on Plant Performance and Ash Disposal'.

The specific objectives of this project were as follows:

To provide boiler operators with a relatively simple means of increasing cycle efficiency and reducing particulate emissions.

To determine the optimum level of mineral additions using an Entrained Flow Reactor.

To identify possible technical showstoppers using pilot scale combustion tests.

To conduct a full scale ash re-firing test.

To undertake a techno-economic assessment of ash re-firing and mineral addition and generate a set of guidelines for re-firing of pulverised fuel ash and mineral addition.

This project has shown that ash re-firing is both technically and financially viable on existing coal fired power plant. It is believed that commercial scale replication of the concept could be undertaken by plant operators using the data gathered by this project as the basis for a full scale development.

This profile contains information on the project's:

Objectives

Summary

Background

Mineral Addition and Ash Re-fitting Trials

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

This document is the final report for the project titled 'Assessment of Ash Re-firing and Mineral Addition - Impact on Plant Performance and Ash Disposal'.

Pulverised coal fired generation plant will continue to play a major role in the world-wide electrical power market for the foreseeable future. Emission standards have become tighter in recent years and coal fired plant has been required to become more flexible in terms of operating regimes. The changes have led to increases in the levels of unburnt carbon in ash, deposition patterns in boilers as well as increased pressure on the performance in electrostatic precipitators.

This project, to investigate if ash refiring and mineral addition were viable methods of improving boiler efficiency and reducing emissions, was supported by the DTI as part of its Cleaner Coal Programme. The project involved the collaboration of two generators (RWE npower and TXU Europe), a major coal supplier (UK Coal) plus two university groups (Imperial College London and the University of Sheffield)

This report has a summary and is divided into the following sections:

1. Introduction
2. Project Overview - Aims, objectives and work programme
3. Coals and minerals selected for the project
4. Mineral addition trials on the Entrained Flow Reactor
5. University of Sheffield MSc projects
6. Pilot scale trials of ash re-firing
7. Pilot scale trials of mineral additions
8. Characterisation of coals, ashes, minerals and deposits
9. The nature of fly ash and its ability to be collected in electrostatic precipitators
10. Power station evaluation of ash re-firing
11. Techno-economic assessment
12. Conclusions
13. List of Participants

The range of coals encountered by new and existing power stations in the UK and abroad is steadily increasing. The inorganic component - the mineral matter - of coal impacts directly on plant availability through coal ash slagging, emission limits especially for fine particulate material and ash use and disposal. These factors constrain the acceptable range of coals for power station use. This project addresses the lack of fundamental understanding of the processes and rates of coal ash formation. It also considers the inability to predict boiler ash properties and behaviour because of a lack of detailed numerical descriptions for fly ash. The objectives of this project are:

To improve understanding of the transformations undergone by major coal minerals during pulverised coal combustion

To provide quantitative data on the rates of coal mineral transformations

To provide quantitative descriptions of boiler ashes, especially finer ash particles, for modelling boilers and precipitators using computational fluid dynamics

To improve understanding of the effect of coal mineral transformations on the processes of boiler ash formation, deposition, emission and disposal

This summary contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

The UK now imports more than 50% of the coal that is used for coal-fired power generation. UK generators are offered an increasingly wider range of world-traded coals for burning in boilers that were designed to burn a relatively narrow range of indigenous coals. This project was undertaken to provide UK boiler designers and operators with an improved knowledge of the combustion characteristics of coals for which they had little combustion experience. The study placed particular emphasis on the effects that a wider range of coal minerals and mineral matter distributions might have on the many aspects of boiler operation. These ranged from coal grinding for pulverised coal combustion, to combustion behaviour, levels of unburned carbon in ash, precipitator performance, gaseous and particulate emissions, and the slagging and fouling characteristics of the ash.

The coals were selected to reflect the wide range of world-traded coals that are now on offer and came from North and South America, Australia, South Africa, Indonesia, China, Russia and India. The coals were chosen on the basis of the ash content and ash chemistry that UK utilities might encounter. As a consequence of the varied geographical origins of the coals and the range of ash chemistry, the nature and distribution of the mineral matter in the coals was found to be significantly different from that of indigenous coals.

Coal and mineral matter characterisation was carried by Nottingham University and Imperial College London. Combustion studies were undertaken by E.ON, using the Combustion Test Facility (CTF) at the Ratcliffe Power Technology Centre and by Imperial College, using a high temperature Entrained Flow Reactor (EFR). In addition the EFR was used to study the mineral transformations of the minerals found in the suite of coals. The combustion facilities generated a range of samples for analysis and characterisation, including combustion ash and unburned char, cyclone ashes and deposits collected on ceramic probes and a slag panel. Characterisation of the samples enabled the combustion performance and slagging propensity of the coals to be assessed and ranked against that of a typical UK bituminous coal (Harworth).

Some of the coals would be unsuitable for UK boilers. Two coals from the US Powder River Basin had a high slagging and fouling potential, a high ash coal from India could give potential ash handling problems unless blended with a low ash coal, and a South African coal gave high NOx and high levels of unburned carbon. The remaining coals would be expected to give few operational problems.

The implications of burning a wider range of imported coals have been considered. Sales of boiler ashes to the construction market are an important consideration in the overall economics of coal-fired power generation. Several of the ashes with a high calcium content would be unlikely to meet current and anticipated specifications for use with cements and concrete.

Existing methods of coal and ash characterisation were found to be generally satisfactory in predicting the combustion performance of the coals burned at rig scale. The more advanced coal and ash characterisation techniques were found valuable in understanding the mineral transformations, the ash formation and ash deposition mechanisms.

This report contains an executive summary, and is divided into the following sections:

1. Introduction
2. Project Overview - Aims and Objectives - Activities
3. Coals and Minerals Chosen for the Project
4. Coal Combustion Characterisation
5. Generation and Characterisation of Ashes from Coal and Mineral Combinations
6. Mineral Transformations and Ash Formation Processes
7. Ash Particle Interactions and Transformations
8. Implications of Findings for Power Station Performance
9. Ash Sales and Ash Disposal
10. Conclusions
11. Further Work
12. References

This document is the final report for the project titled 'Coal-Fired Advanced Supercritical Retrofit with CO₂ Capture '.

The overall aim of the project (DTI Project 407) is to evaluate the technical and economic feasibility of retrofitting UK coal-fired power plants with advanced supercritical boiler/turbine technology (ASC BT) and carbon dioxide capture. Specific objectives were:

To establish optimum ASC BT retrofit solutions for the reference power plant site selected for study (Ratcliffe) judged to be typical of the majority of the UK coal fleet (500 MWe and larger).

To determine the relative benefits of alternative approaches to the possible staging of retrofits for the short-term (capture-ready ASC BT retrofit) or the long-term (ASC BT retrofit with CO2 capture).

To review the applicability of the optimum retrofit solutions for a range of UK coal fired power plant sites (including Drax and West Burton) and to provide an indication on the variances arising due to site conditions.

Retrofit of carbon abated clean coal technologies (CATs) is a practical solution with no technical or physical show stoppers being identified in the course of the study. Advanced supercritical boiler/turbine (ASC BTR) technology is available now with the appropriate guarantees for retrofitting to coal-fried power plant to improve efficiency, reduce costs and reduce carbon dioxide emissions.

When CO2 capture and storage becomes economic or mandatory the retrofit routes studies are likely to be amongst the best and most economic options for existing pulverised fuel power generation plant. The project consortium members (Doosan Babcock, Alstom, E.ON UK, Air Products, Imperial College London and Fluor Ltd) are well positioned to exploit the opportunities worldwide.

This report contains an executive summary, and is divided into the following sections:

1. Introduction
2. Technical Description of Results
3. Recommendations
4. Results and Conclusions
5. Acknowledgements
6. References

The objectives of this project were:

To develop Self-Illuminated Video (SIV) and image analysis techniques to identify adverse combustion conditions in utility PF boilers.

To provide a number of quantifiable parameters from video images which can be used to evaluate flame stability and combustion.

To develop PC software to transfer key parameters to existing data logging systems in real-time.

To develop systems to transmit and integrate video data from a number of cameras, under actual boiler plant conditions.

To determine optimum video probe designs and locations for quantitative SIV on utility boilers.

All project objectives have been achieved. As planned, video capture and processing equipment was installed and tested on actual boiler plant early in the project and the results of practical experience used progressively to inform and refine developments.

This experience has confirmed the importance of proving techniques under actual PF combustion techniques. Work by Imperial on a number of other video projects involving observations in small-scale furnaces has shown that the technical challenges involved in acquiring satisfactory video data are much more severe in full scale plant. Different combustion-related phenomena are also encountered in practice.

This summary contains information on:

Objectives

Summary

Background

Video Probe Placement for Combustion Monitoring

Video Observation from Corner Door Locations

Oil Guntube Video Probe Trials

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

The objectives of this project are:

To demonstrate the combustion performance of a low volatile coal burner for wall fired furnaces by testing of a full-scale burner design in a single burner test facility.

To optimise the furnace design and process for utility plant and burner retrofits with regard to combustion efficiency, NOX missions, and stability/turndown performance by means of pilot scale testing and advanced modelling techniques.

The main aim of the project was to demonstrate the proposed low volatile burner at full scale in a single burner test facility and to establish its performance with regard to NOX and combustion efficiency. Furthermore, pilot scale testing was undertaken to quantify the effect of the staged addition of combustion air. Air staging is generally regarded as an effective, mature technology for NOX reduction from bituminous coals, but its impact on low volatile coals is less well understood.

This summary provides information on:

Objectives

Summary

Background

Results

TGA

High Temperature Volatile Yield

Explosibility Test

Full Scale Burner Tests

Air Staging Tests

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

Specific objectives for this project are:

To identify the limitations of ignition and flame stability when firing low volatile coal in existing Low NO_x axial swirl burner technology.

To identify the requirements for burner design modifications to extend the lower limit of volatile matter content that can be fired down to 10% or lower.

To correlate the fuel ignition stability to measurable fuel properties and develop existing fuel testing methods to provide enhanced fuel ignition/stability characterisation data.

To demonstrate the combustion performance of a low volatile coal burner for wall fired furnaces by testing a full-scale burner design in a single burner test facility.

Traditionally low volatile coals and anthracites have been utilised in arch fired furnaces (often referred to as 'downshot' firing) so as to overcome the inherent difficulties of achieving stable and efficient combustion which arise from the lack of volatile material in the coal to aid in the ignition, and the low reactivity of the remaining char. The downshot firing system is, however, of higher initial cost than a comparable wall fired system, and if it were possible to utilise low volatile coal in wall fired furnaces there are clear economic benefits both in retrofit applications and for new plant.

In Phase 1 of the project the key mechanisms for ignition and stabilisation of low volatile coal flames were identified. A conceptual burner design for firing coals down to 10% VM daf was outlined. In Phase 2 of the project the aim is to develop further a burner design specifically for firing of coals of lower volatile matter content down to ca. 10% daf. It will be necessary to determine more closely the limit of volatile matter on ignition and stability with existing Low NO_x Burner technology and investigate the actual/relative sensitivity of ignition/stability to variations in the key mechanism parameters identified in Phase 1. The burner design developed in the project will be tested at full-scale

This summary provides information on:

Objectives

Summary

Cost

Duration

Contractor

Collaborators

Objectives of project:

To develop self-illuminated video (SIV) and image analysis techniques to identify adverse combustion conditions in utility PF boilers.

To provide a number of quantifiable parameters from video images which can be used to evaluate flame stability and combustion.

To develop PC software to transfer key parameters to existing data logging systems in real-time.

To develop systems to transmit and integrate video data from a number of cameras, under actual boiler plant conditions.

To determine optimum video probe designs and locations for quantitative SIV on utility boilers.

This report is divided into the following sections:

1. Technical Background
2. Project Objectives and Achievements
3. Techniques and Results
4. Conclusions and Future Work

The objectives of this project are:

To develop a prototype optical instrumentation system capable of measuring the distributions and fluctuations of temperature and soot concentration of pulverised coal flames.

To evaluate the performance of the system on a 0.5MWth combustion test facility at Innogy plc over a range of combustion conditions.

To establish quantitative relationships between the flame temperature and soot concentration measured and the corresponding combustion input data, thermal output and emission levels.

As a result of this project, a prototype instrumentation system for the concurrent measurement of flame temperature and soot concentration has been developed. The system operates on the principle of multi-wavelength pyrometry combined with digital imaging and image processing techniques. A monochromatic imaging system is used to visualise the flame field in the furnace. The flame light incipient on the optical sensor installed on the furnace wall is split into separate beams passing through narrow band-pass filters of different wavelengths before reaching the imaging device. The resulting digital images are processed to determine temperature distribution of the flame field. The soot concentration of the flame is represented using a parameter called KL factor, which is derived from the temperature measured. The operability and effectiveness of the system have been evaluated on an industrial-scale combustion test facility operated by Innogy plc.

Results obtained have demonstrated that the system is capable of measuring two-dimensional distributions and fluctuations of flame temperature and soot concentration. The accuracy of the system was verified using a tungsten lamp as a standard reference source. The relative error between the measured temperature and the reference temperature was found to be no greater than 1% throughout the measurement range from 1280°C to 1690°C. The resolution of the system was dependent upon the resolution of the camera and its installation on the furnace. The prototype system was applied to investigate the distributions of flame temperature and soot concentration of typical pulverised coals. Quantitative relationships between flame temperature, soot concentration and corresponding plant conditions were identified. Preliminary comparisons between the pulverised coal flames and other fossil fuel flames were also undertaken.

This summary provides information on:

Objectives

Summary

Cost

Duration

Contractor

Collaborator

Background

Methodology

System Description

Experimental Evaluation

Trials on Innogy's Combustion Test Facility

Conclusions

In order to examine the corrosive effects of co-firing biomass with coal in existing subcritical and possible future (ultra) supercritical boilers, typical and potential boiler tube alloys have been exposed to simulated furnace wall and superheater/reheater environments in the 1MWTH pulverised coal fired Combustion Test Facility (CTF) at Power Technology. A total of four CTF runs have been completed, each of which were nominally of 50 hours duration. Up to 15 furnace wall and 16 superheater/reheater steel alloy specimens were exposed to a range of metal temperatures, with differing heat fluxes and gaseous environments, representative of pulverised coal combustion under low NO_x conditions with biomass additions. The biomass fuels were co-fired with Daw Mill coal, furnace wall corrosion specimens having previously been tested without biomass additions in this environment, providing base line corrosion data for comparison. Numerous previous tests with coals provided baseline data for superheater/reheater corrosion rates. Biomass was fired at both 20% and 10% on a thermal basis, representing proportions significantly above and close to the maximum proportions expected to be utilised in actual plant, enabling examination of concentration effects. The specimens were exposed to the combustion environment on air-cooled, precision metrology, corrosion probes.

When co-firing with wood at both 20% and 10% on a thermal basis, there was no discernable worsening of either furnace wall or superheater/reheater corrosion when compared with firing coal alone. Whilst there was no comparable data for TP316 austenitic stainless steel superheater/reheater specimens, the measured corrosion rates were substantially reduced when compared to the ferritic T22 specimens exposed at the same location.

This report is divided into the following sections:

1. Introduction
2. Experimental Program
3. Results
4. Discussion
5. Conclusions
6. Recommendations
7. References

The main objectives of this project were to:

Compare the current low calorific value (LCV) diffusion flame combustion system design against a lean premix combustion system (based on the ALSTOM G30 design) and a catalytic combustion design approach.

Provide a recommendation on the way forward for the commercial exploitation of the LCV and medium calorific value (MCV) gas fuel market, particularly for biomass and underground coal gasification applications.

The project evaluated the relative merits of three different systems for burning low calorific value gas. These were a diffusion flame combustion system (current Värnamo/ARBRE build), a lean premix combustion system (based on the ALSTOM-Lincoln premium fuelled G30 design) and a catalytic combustion system. The evaluation was based on assembly and analysis of:

The significant existing test data for the diffusion flame combustion system and bench-mark testing using a high pressure rig at Cranfield University.

High pressure rig testing of the lean premix combustion system at Cranfield University.

Data on catalytic combustion from the open literature and from a previous Foresight Challenge funded project.

This summary provides information on:

Objectives

Summary

Background

DLE Combustor Design

Combustor Testing

Recommendations

Cost

Duration

Contractors

The specific objectives of the project are:

To demonstrate the performance of a full-scale burner capable of utilising difficult coals (i.e. low volatile content and/or high inert content) with regard to NO_X emission, combustion efficiency, turndown without oil support, and flame stability.

To obtain characterisation data for difficult coals, and to apply this data in improved combustion models.

In-furnace NO_X reduction technologies, and low NO_X burners in particular, are considered mature for application to a wide range of coals. However their performance deteriorates with the more 'difficult' coals; i.e. low volatile coals (<10% daf) and those with high levels of moisture and/or high levels of inert materials. Such coals are being utilised increasingly in large export markets such as Eastern Europe, India, Asia and the United States. The problem with difficult coals is in achieving a stable performance with low emissions and efficient combustion. For example, the presence of high levels of moisture causes a delayed ignition resulting in the flame front not being stabilised within the burner throat as is normal with bituminous coals. Consequently, the burner is significantly less effective in controlling both NO_X emissions and combustion efficiency. The presence of high ash compounds this problem.

The proposed project aims to develop and demonstrate a new burner type capable of firing a range of difficult coals, at full-scale in a single burner test facility. The development phase will employ advanced modelling techniques for investigation of the effects of ignition, devolatilisation and burnout behaviour for difficult coals. This will be combined with detailed coal characterisation data. Burner design and performance implications as a result of integrated CO₂ capture options will be considered.

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This document is a report for the project titled 'Development of Stable Isotopic Ratio Measurement - Apportioning of Fuel and Thermal NO_x'.

The main aims of the project have been to develop a nitrogen-stable isotope measurement technique for NO_x and to ascertain whether it can be used to determine the relative contributions of fuel and thermal NO_x during coal combustion at high temperatures. Suitable substrates for adsorbing sufficiently high concentrations of NO_x from flue gas streams to facilitate the reliable measurement of the nitrogen stable isotope ratios were developed, the substrates encompassing both manganese oxide supported on zirconia (MnOy-ZrO2) and iron supported on active carbon (Fe/AC, first milestone completed October 2001).

This report is divided into the following sections:

1. Introduction
2. Technical Progress/Overall Planning and Objectives Summary
3. Expenditure
4. Exploitation/Publication of Results

• Appendix 1 - Background nitrogen levels in EA-IRMS for the Europa 20:20 instrument
• Appendix 2 - Tables
• Appendix 3 - Details on nitrogen stable isotope measurements obtained using the N-free Fe/Mn-AC

This document is a summary report for the project titled 'Enhanced Efficiency Steam Turbine Blading - For Cleaner Coal Plant'.

The aim of this project was to increase the efficiency of the short height stages typically found in high pressure steam turbine cylinders. For coal fired power plant, this will directly lead to a reduction in the amount of fuel required to produce electrical power, resulting in lower power station emissions. The continual drive towards higher cycle efficiencies demands increased inlet steam temperatures and pressures, which necessarily leads to shorter blade heights. Further advances in blading for short height stages are required in order to maximise the benefit. To achieve this, an optimisation of existing 3 dimensional designs was carried out and a new 3 dimensional fixed blade for use in the early stages of the high pressure turbine was developed.

The milestones for the project were defined around the following specific objectives:

Increase the accuracy and execution speed of in-house C.F.D. codes.

Develop new CNC techniques to efficiently produce model turbine blade rows with highly curved 3-D blades.

Optimise existing 3-D fixed blade designs to improve performance and gain better understanding of how to deal with very short height blading.

Produce a novel design for very short height fixed blades.

Perform a model air turbine test on the new design of fixed blade to assess the performance benefit gained from it.

The work that CCLRC undertook on the ALSTOM C.F.D. code was very successful. The 3-D flow solver code supplied by ALSTOM was analysed and two methods of parallisation implemented. The OMP method of parallisation is only suitable for use on "shared memory" multi-processor computers. The MPI method of parallisation is suitable for use on "distributed memory" computers, sometimes know as "Beowulf Clusters", which tend to be significantly cheaper to buy than large shared memory computers of similar processing power. As a result of this work, ALSTOM Power have purchased a Beowulf Cluster, and it has become the main workhorse of the Aerodynamics Group.

This report is divided into the following sections:

1. Introduction
2. Analysis of the Project
3. Improved Computational Grid Generation
4. Optimisation of Current Controlled Flow Design
5. Development of Very Short Height Fixed Blades
6. Improved Methods for Producing Model Turbine Components
7. Model Turbine Test of Very Short Height Fixed Blade
8. Summary and Conclusions

The aim of this project is to increase the efficiency of the short height stages typically found in high pressure steam turbine cylinders. This will directly lead to a reduction in the amount of coal required to produce electrical power, resulting in lower power station emissions. In order to do this, the following tasks must be undertaken:

Increase the accuracy and execution speed of in-house CFD codes

Develop new Computer Numerically Controlled (CNC) techniques to efficiently produce model turbine blade rows with highly curved 3-D blades

Optimise existing 3-D fixed blade designs to improve performance and gain better understanding of how to deal with very short height blading

Produce a novel design for very short height fixed blades

Perform a model air turbine test on the new design of fixed blade to assess the performance benefit gained from it

The benefits of the project include:

Reduces power station emissions through more efficient use of fuel

Keeps the UK steam turbine industry at the forefront of technology

Increases the value of retrofit solution offered to customers (typically £700 per kilowatt)

Maintains ALSTOM's competitive advantage in the impulse retrofit steam turbine market. Last year ALSTOM won overseas orders worth over £42 million in this area of the company's business

This profile contains information on the project's:

Objectives

Summary

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Duration

Contractor

The aim of this project was to increase the efficiency of the short height stages typically found in high pressure steam turbine cylinders. For coal-fired power plant, this would directly lead to a reduction in the amount of fuel required to produce electrical power, resulting in lower power station emissions. The continual drive towards higher cycle efficiencies demands increased inlet steam temperatures and pressures, which necessarily leads to shorter blade heights. The specific objectives were as follows:

To increase the accuracy and execution speed of in-house Computational Fluid Dynamic modelling (CFD) codes.

Develop new Computer Numerical Control (CNC) techniques to efficiently produce model turbine blade rows with highly curved 3D blades.

Optimise existing 3D fixed blade designs to improve performance and gain better understanding of how to deal with very short height blading.

Produce a novel design for very short height fixed blades.

Perform a model air turbine test on the new design of fixed blade to assess the performance benefit gained from it.

The aim of this project was to increase the efficiency of the short height stages typically found in high pressure steam turbine cylinders. Whilst the reasons for this are still not understood, the result has led to changes in the way that such blades will be designed in the future. It also provides a challenging test case for future CFD code validation.

This summary provides information on:

Objectives

Summary

Background

Overview of the Project

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

Further Information

The objectives of this project are:

To develop a model that allows the value of operational flexibility (or the cost of inflexible plant) to be calculated.

To apply that model for typical plant data for coal-fired integrated gasification combined cycle plant and conventional PF plant to calculate the benefits of operational flexibility.

To apply the model to Integrated Gasification Combined Cycle (IGCC) plant with varying levels of integration (which affects start-up times) and also to optional hydrogen production.

This project was set up by E.ON to investigate ways of putting a monetary cost to plant inflexibility. The project was undertaken in collaboration with UMISTs Department of Process Integration, who are world leaders in the science of process optimisation and who possess the necessary optimisation and computing expertise. The DTIs interest is primarily because of the importance of this subject to IGCC; however, the issue is of general applicability to all types of generating technology.

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Objectives

Summary

Background

Methodology

Hydrogen Co-Production

Results

Conclusions

Cost

Duration

Contractor

Collaborators

The aims of this project were:

To reduce the capital and through life cost of steam turbines generating with clean coal technologies at steam temperatures above 570°C.

To develop the materials and welding technology necessary to provide a fabricated steam turbine rotor to operate with elevated steam temperatures in the high temperature part and long, high strength, turbine blades in the low temperature part of the rotor.

To fully characterise the microstructures and properties of such steam turbine rotors to enable the development of lifeing methodologies.

An investigation has been made into the possibility of welding together 10%Cr and 3.5%NiCrMoV rotor steels, a combination which would allow manufacture of large turbine rotors with inlet steam temperatures in excess of 570°C.

Following a comprehensive modelling programme by the University of Cambridge and complementary testing and examination by Siemens Power Generation (SPG), a welding procedure was developed and successful narrow gap TIG welds were made between 380mm diameter, 50mm thick material. This was accomplished using the established Tungsten Inert Gas (TIG) filler wire.

This summary provides information on:

Objectives

Summary

Background

Development Procedures

Conclusions

Future Work

Cost

Duration

Contractor

Collaborators

Further Information

This document is a report for the project titled 'Fabricated Turbine Rotors - Advanced Steam Turbines'.

An investigation has been made into the possibility of welding together 10%Cr and 3.5%NiCrMoV rotor material in order to produce the next generation steam turbines operating above 570°C.

Following a comprehensive modelling programme and complementary testing and examination by Siemens Power Generation (SPG) and the University of Cambridge, a welding procedure was developed and successful plate and small diameter welds were made between sections of 3.5%NiCrMoV and 10Cr material. Mechanical and metallurgical assessment of these welds showed that the weldment properties matched the requirements of the original parent material.

Following the success of the initial welds, a large-scale weld has been manufactured using the established materials and procedures to fully validate the developed welding procedure. This weld has been subjected to non-destructive examination (NDE) followed by extensive mechanical and metallurgical testing. The results confirm that the large scale weldment properties matched the requirements of the original parent materials and thereby satisfy the objectives of the project.

This report is divided into the following sections:

1. Summary
2. Introduction
3. Objectives of the Project
4. Technical Challenges
5. Development Procedures
6. University of Cambridge Modelling
7. Development Welding Trials
8. Full-Scale Welding Trial
9. Conclusions
10. Figures 1 to 9

Steels for advanced steam turbines operating within super-critical steam conditions have been developed within the COST 501 collaborative programmes and are continuing to be developed within the COST 522 programme. The data generated has already been used to develop and design high temperature turbines which are now in operation or at an advanced stage of construction.

New cleaner coal power generation technologies such as air blown gasification combined cycle (ABGC), integral gasification combined cycle (IGCC) and fluidised bed combustion will be looking to utilise these new steels in steam turbines but costs will need to be reduced to improve their competitiveness. The objectives of the project are:

To reduce the capital and through life cost of steam turbines generating in combined cycles with clean coal technologies

To develop the materials and welding technology to provide a fabricated steam turbine rotor to operate with supercritical steam temperatures in the high temperature part and long, high strength turbine blades in the low temperature part of the rotor

To characterise fully the microstructures and properties of such steam turbine rotors to enable the development of lifing methodologies

These combined cycle plants will generate in the region of 350 MW to 400 MW and will utilise steam turbines with an output in the range of 120 MW to 250 MW. The cost of the steam turbine can be reduced considerably if the number of turbine cylinders is reduced. A single cylinder reheat turbine would be adopted for smaller outputs and a two cylinder turbine with an HP turbine and a combined IP/LP turbine for the larger outputs. The requirement for a single rotor forging steel that has good creep properties at temperatures of 570°C and greater combined with high strength and toughness to carry long turbine blades at the low pressure end cannot be met by the COST steels alone.

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The objectives of this project were:

To determine the effect of co-firing biomass with coal on boiler tube fireside corrosion rates in existing subcritical coal fired power plants.

To determine the likely fireside corrosion rates that could be expected on boiler tubing in future advanced (ultra) supercritical power plant.

Typical and potential boiler tube alloys have been exposed to simulated furnace wall and superheater/reheater environments in the 1MW_Th Combustion Test Facility (CTF) at Power Technology.

A total of four nominally 50 hour duration exposures have been completed. Specimens were exposed to a range of metal temperatures, heat fluxes and gaseous environments, representative of pulverised coal combustion under low NO_x conditions with biomass additions. Biomass was co-fired with Daw Mill coal on 20% and 10% thermal or heat input basis (approx 35% and 17% by mass). Specimens were exposed to the combustion environment on air-cooled, precision metrology, corrosion probes.

This summary provides information on:

Objectives

Summary

Background

Corrosion Testing

Wood Co-Firing

Cereal Co-Product Co-Firing

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

The objectives of this project are:

To generate and assess cross-weld creep rupture data on welded joints failing by the Type IV Heat-Affected Zone (HAZ) cracking mechanism in steels for high temperature application in advanced PF plant.

To assess the long term risks of welded plant component failure.

To optimise steel selection for thick section high alloy ferritic steel components in advanced coal-fired power plant.

To provide a sound basis for determining appropriate limiting plant design temperature and stress conditions.

Type IV cracking in the weld Heat-Affected Zone (HAZ) is likely to be the critical problem which will limit design conditions for satisfactory operation of advanced PF plant. The FOURCRACK project carried out high temperature creep testing of welds in advanced high alloy steels with a range of specifications, supplemented by specialised testing, optical and electron metallography, weld simulation and data assessment. Further work outside FOURCRACK will extend testing to longer durations.

E.ON UK led the project and undertook metallurgical investigation and assessment. Mitsui Babcock carried out weld manufacture and creep rupture testing. RWE npower investigated and characterised a special weak material. In parallel work, Loughborough University carried out electron metallography and weld simulation. Five external organisations also provided test materials and/or weldments.

This summary provides information on:

Objectives

Summary

Background

The FOURCRACK Project

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

The recently completed project 'Practical Improvements in Power Plant Engineering (PIPPE)' - part of the DTI Cleaner Coal Programme - has highlighted weld heat-affected zone "Type IV" cracking as a principal concern in advanced high temperature plant. Current creep test data, inevitably obtained on a much shorter timescale than the projected life of plant, suggest that weld performance could substantially deteriorate in the longer term. Better data and extrapolation techniques are needed to assess the extent of this threat to plant reliability and thus develop effective countermeasures that will gain the confidence of prospective plant purchasers and operators.

This project will help manufacturers gain a fundamental understanding of why the weld heat-affected zone is susceptible to "Type IV" cracking in high temperature service, how its susceptibility is related to steel composition and heat treatment, and, consequently, how advanced steels can best be selected and developed to minimise these risks. The main objectives are:

To generate longer term creep rupture test data on advanced steel weldments

To develop better techniques for the prediction of weld creep life in service from laboratory test data

To thereby assess the long term risks associated with "Type IV" cracking in welded high alloy steels for advanced plant

To determine the optimum steel choices for welded thick section advanced PF plant components such as headers and steam pipework

To determine appropriate limits on plant operating temperature and stress conditions to ensure the reliable long term operation of welded components

The FOURCRACK project will produce and assess cross-weld creep rupture test data on welds in advanced high temperature steels. The leading competitor materials will be critically compared. New welds will also be compared with simulated service aged and repair welds. Weld thermal simulation and microstructural assessment will be employed to gain a better understanding of the causes of "Type IV" cracking

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The objectives for this project are:

To develop materials with 100,000 hour creep strength at 650°C and 100MPa and improved resistance to steam oxidation, whose use will result in increases in plant operating efficiency and thereby reduce carbon dioxide emissions.

Increase understanding of microstructural evolution in advanced materials and weldments, steam oxidation mechanisms, and coating degradation mechanisms.

Mechanical behaviour of advanced materials and weldments on laboratory samples and full size prototype components.

Demonstration of prototype manufacturing, joining, non destructive examination and coating capabilities for large components.

Improved efficiency in coal-fired power plant can be achieved by increasing steam temperatures and pressures, and this has been made practically possible over a number of years by the development of steels with improved creep strength enabling operation up to 600-620°C at present. In Europe a new initiative (COST 536) has been launched, entitled 'Alloy Development for Critical Components of Environmentally Friendly Power Plant (ACCEPT)', and encompasses all stages in the development and validation of advanced steels capable of operation at temperatures up to 650°C. The primary route of achieving this is through the development of new alloying and coating concepts.

This project focuses on the validation testing of the capabilities of a new class of steels and their weldments at temperatures up to 650°C and the longer term qualification of advanced steels developed under COST 522. The project has been accepted for inclusion in the COST 536 initiative.

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This document is the final report for the project titled 'Gas Turbines Fired on Coal Derived Gases - Modelling of Particulate and Vapour Deposition'. This report is titled 'Alkali Salt Vapour Deposition on Gas Turbine Blades.'

The following report describes the development of a computer program for calculating deposition rates of alkali salts from two-dimensional turbulent boundary layer flows on turbine blades. The description of the program was originally submitted as the Milestone 1 Report of the project. This description is included here, but with additional sections summarising the background and theoretical approach of the work and the application of the code to an example cleaner-coal turbine.

The development and testing of the new code involved:

1. Conducting a literature search for thermochemical data on the alkali oxide/hydroxide system;
2. Deriving appropriate thermochemical constants and parameters;
3. Revising the existing models to incorporate the alkali oxides and hydroxides;
4. Incorporating the new model into a computer program to estimate the boundary layer diffusion and surface deposition rates of the alkali salts;
5. Performing sample test calculations with the new computer program.

There is considerable potential for exploitation of the existing computer code. As it stands, the code should be of interest to those companies involved in the design and manufacture of the type of heavy-duty industrial gas turbine which will be required in the future for coal-fired operation. The main companies operating worldwide are General Electric in the United States, Alstom in the United Kingdom, Siemens in Europe, and Mitsubishi and Hitachi in Japan. The Whittle Laboratory at Cambridge University has close contact with most of these (and other) companies and it is proposed to investigate the possibilities for marketing of the code and establishing other consulting arrangements.

There is also potential for further scientific development of the thermochemical modelling. Although attention has been confined in the present project to the salts of sodium and potassium and their behaviour in high temperature gas flows, the method of analysis is fairly general and could be extended to encompass other situations. For example, two problems of current interest which might respond to similar modelling techniques are the transport of corrosive vanadium salts to gas turbine blades in conventional gas turbines and corrosion of steam turbine blades by sodium salts present in the feedwater. In the United Kingdom, companies such as Rolls-Royce, Alstom and Siemens will be approached for discussion on the possibility of extending the modelling to deal with these and other technical problems.

This report is divided into the following sections:

1. Introduction
2. Outline of the Theory
3. The Computer Program 'VAPOURDEP'
4. Testing and Validation of the Program

The remainder of the report consists of a user manual for VAPOURDEP written by J.B. Young, and Appendices:

• Appendix 1 - Equilibrium of Sodium and Potassium Species in the Gas Phase
• Appendix 2 - Species Conservation Equation
• Appendix 3 - Grid Generation
• Appendix 4 - Finite Volume Solution of the Species Continuity Equations
• Appendix 5 - Specification of the Initial Concentration Profiles
• Appendix 6 - Calculation of Mass Transfer Coefficients
• Appendix 7 - Equilibrium at the Gas-Deposit Interface
• Appendix 8 - Thermodynamic Properties

The project aims to provide boiler operators with greater confidence in using higher levels of biofuel replacement (50% thermal or more). The specific objectives of the project are:

Identification of the main areas of the boiler at risk if biomass is co-fired with coal at 50% or more of thermal replacement

Determination of the nature of deposits likely to form in the radiant and convective passes of the boiler. Measurement of the physical and mechanical properties of the deposits to determine thermal shock and sootblowing properties

Development of a model to predict the thermal impact of fouling deposits and to optimise sootblowing operations

Assessment of the use of low cost additives to mitigate the effects of alkali metal fouling from biomass residues

A technical and economic assessment of the viability of high levels of biomass co-firing, including recognition of current CO2 abatement levels and other environmental constraints

The increased use of biomass, a fuel that is seen as largely CO2 neutral, in power generation is one of the few ways in which the power industry could make a significant step to reducing CO2 emissions. Co-fired boiler trials have been encouraging and have shown that small amounts of coal can be replaced by biofuels without undue impact on boiler performance. However, in order to make a real impact towards reaching Government targets, the amount of biomass for co-combustion would have to be greatly increased.

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The overall aim of the project is to ensure the continued participation of major UK power generation organisations in the European Co-operation on Science and Technology COST 522 initiative. The project covers two distinct areas of the COST 522 initiative, steam power plant and plant integration & ancillary components. The specific objectives of these two groups within COST 522 are to demonstrate advanced components for the supercritical boiler and steam turbine that will permit thermal efficiencies of 50% to be achieved and to develop technology (gasification, heat exchanger, hot gas clean-up) for alternative cycles and fuels that will play a major part in future high efficiency low emission power plant. Specific objectives for the participants within the project are the development of:

Advanced material technologies to enhance the performance of critical components thereby increasing efficiencies and reducing plant emissions

Lifing techniques and methods to improve prediction of materials and component behaviour under service loading, leading to accurate life prediction, improved design, reduced plant downtime and increased availability

Plant integration, advanced control and monitoring techniques to enhance the performance, reliability and availability of mechanical systems and to optimise plant performance

Strategies and business opportunities for UK companies in the power generation sector will also be identified.

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The objectives for this project are:

Review previous work to predict combustion efficiency.

Identify how prediction can be made faster and more reliable than existing methods.

Develop the ability to predict how a coal will perform on a given boiler (to include ability to allow for specific plant features, eg mills and coal fineness, air ingress).

Provide a predictive tool which can be used to quantify combustion improvement from proposed plant modifications.

The overall aim of the project was to develop new tools for the reliable and rapid prediction of combustion efficiency of coals in pf-fired utility boilers. This would give the ability to improve fuel selection and chose the most appropriate burner and boiler design for a given fuel.

The conclusions of this project are:

Various ways have been identified to enable the prediction of combustion efficiency (carbon burnout) to be made faster and more reliable. This has been done partly by examining the strengths and weaknesses of existing methods within the review. In addition, the key physical processes have been identified and the currently available methods for modelling them have been tested. This has enabled the most promising methods to be further developed.

Two new approaches have been developed to predict how a coal will perform on a given boiler. One is an empirical correlation for a single power station and the other is a computer model applicable to any specific coal and power station. The latter includes the ability to allow for specific plant problems, eg mills, air ingress. Software has been developed for such a generic carbon-in-ash predictor and has supplied to project participants and tested by them. It shows promise but requires further development.

The generic carbon-in-ash predictor developed within the project can, in principle, provide a predictive tool which can be used to quantify combustion improvement from proposed plant modifications.

This summary provides information on:

Objectives

Summary

Background

Review Burnout Predictions and Data

Coal Selection

Power Station Trials

Rig Testing

Appraisal of PC Coal Lab

Appraisal of an In-House Predictor

Development of a Burnout Model

Comparison of Methods for Estimating Carbon-In-Ash

Conclusions

Cost

Duration

Contractor

Collaborators

The aims of this project were:

To develop a high efficiency cyclone grit arrestor suitable for retrofitting to existing coal-fired boilers. This would enable existing coal-fired boilers to meet future emissions limits in terms of particulates.

To control particulate emissions rather than improving the combustion rates of poor quality coals.

Cover the commercial and industrial segments with a range of boiler outputs from 0.6 MW_th - 6.5 MW_th.

This project is concerned with the design and demonstration of a high efficiency cyclone grit arrester which could potentially achieve a particulate collection efficiency of in excess of 98%, making it suitable for reducing the emissions from boilers of this size and type.

The successful particulate and emission reductions would enable coal to be a viable fuel for heating and process applications in the smaller range of boilers in terms of environmental acceptability.

The conclusions from this project are:

The results exceeded expectations in terms of measured particulate emissions with low rates being achieved in both high and medium fire tests, significantly below the 150 mg/m³ proposed in the small combustion plant directive.

For all the tests and all three-test coals the stack emissions were less when the blow down system was in operation.

Generally, the tests indicated the lowest stack concentration at blow down rates of around 10% under medium firing rates.

Under high firing rates the tests indicated the lowest stack concentration at blow down rates of around 20%.

This summary provides information on:

Objectives

Summary

Background

Cyclone Design and Testwork

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

Further Information

There are thousands of coal-fired boilers in the commercial and industrial sector throughout the world with the biggest impact on the environment being particulate emissions. The market area in terms of boiler output is from 0.6MWth - 6.5MWth output and the number of boilers when aggregated, results in a large potential source of pollutants. The types of combustion equipment commonly used in this sector in China, India, and the CIS are chain grate or travelling grate stokers.

The results of the trials conducted in this project exceeded expectations in terms of measured particulate emissions with low rates being achieved in both high and medium fire tests, significantly below the 150mg/m³ proposed in the Small combustion Plant Directive. If further work was carried out then it could be possible to achieve further reductions in emissions as some of the test results showed emissions levels at around 50-60mg/m³.

This report is divided into the following sections:

1. Introduction
2. Technical background to the project
3. Grit arrestor design and installation
4. Commissioning of boiler
5. Cyclone blow down test work
6. Test results and discussion
7. Technology suitability and efficiency to selected coals from targeted countries
8. Identification of hierarchy of export opportunities
9. Dissemination of information

This proposal is concerned with improving the design, efficiency and environmental performance of low-grade coal burning appliances - commonly used in China, India and the former Soviet Union (FSU) - which produce unacceptable environmental pollution mainly in the form of particulate emissions. In the initial draft of the small combustion plant directive limits for particulates are set at 150 mg/m³ for boilers less than 10 MW, and 50 mg/m³ for those between 10-50 MW. These suggested figures raise considerable challenges for industry. Our objectives are therefore:

To develop a high efficiency cyclone grit arrestor suitable for retrofitting to existing coal fired boilers

To develop a technology suitable for countries burning low grade coal particularly India and China, thereby increasing export opportunities

To develop a system for equipment burning low grade coal which drastically reduces particulate emissions, thereby improving environmental performance

For new boiler plant the successful particulate and emission reductions would enable coal to be a viable fuel for heating and process applications in the smaller range of boilers. In countries such as India, China and the FSU that currently burn low-grade coal as their primary energy source, the impacts of this work could be essential to its future use.

This profile contains information on the project's:

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The objectives of this project are:

To assess the potential corrosive effects of deposits formed on coal-fired and coal/waste co-fired gasifier fuel-gas/syngas heat exchangers in Air Blown Gasification Cycle (ABGC) and Integrated Gasification Combined Cycle (IGCC) systems.

To determine the composition ranges of deposits in ABGC and IGCC fuel-gas/syngas heat exchangers.

To quantitatively assess the rates at which these deposits cause downtime corrosion and the effectiveness of proposed preventative measures.

To assess the potential for the deposits to cause synergistic degradation (at high and low temperatures), and to measure the resulting increase in material damage rates.

To identify exposure/operating conditions/materials which could lead to rapid heat exchanger failures.

A wide variety of gasification systems are continuing to be developed around the world, including Integrated Gasification Combined Cycle (IGCC) and the UK developed Air Blown Gasification Cycle (ABGC) systems. Originally, these systems were developed to be fired on various grades of coal, but there is now interest in using a more diverse range of solid fuels (e.g. co-firing coal with waste or biomass, using low grade coals and heavy fuel oils) in order to reduce environmental impact and fuel costs.

All gasification technologies require a heat exchanger (often called either a syngas cooler or fuel gas cooler) between the gasifier and the gas cleaning system. The duty required from this heat exchanger varies depending on the type of gasifier, gas-cleaning requirements (e.g. hot dry cleaning or wet scrubbing) and steam cycle needs.

The data generated has been used to identify safe operating windows where factors do not combine to produce rapid heat exchanger failures. Aspects such as candidate heat exchanger materials, gasifier type, fuel and fuel gas compositions, deposit compositions and heat exchanger operating conditions have been investigated.

This summary provides information on:

Objectives

Summary

Background

Deposit Formation on Gasifier Hot Gas Path Components

Downtime Corrosion Testing

Downtime Corrosion Testing and Preventative Measures

Synergistic Testing

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

Further Information

A wide variety of gasification systems are continuing to be developed around the world, including Integrated Gasification Combined Cycle (IGCC) and the UK developed Air Blown Gasification Cycle (ABGC) systems. Originally, these systems were developed to be fired on various grades of coal, but there is now interest in using a more diverse range of solid fuels (e.g. co-firing coal with waste or biomass, using low grade coals and heavy fuel oils) in order to reduce environmental impact and fuel costs.

All gasification technologies require a heat exchanger (often called either a syngas cooler or fuel gas cooler) between the gasifier and the gas cleaning system. The duty required from this heat exchanger varies depending on the type of gasifier, gas-cleaning requirements (e.g. hot dry cleaning or wet scrubbing) and steam cycle needs. However, gasifier hot gas path environments are potentially very aggressive for materials both during plant operation and off-line periods. This has the effect of imposing a temperature window for the safe operation of these heat exchangers (with current materials restricting their use to modest steam conditions and preventing their use as superheaters with commercially viable lives) and dictates that downtime corrosion control precautions are required during off-line periods. There are significant differences in the hot gas path environments between the various gasification systems and with different fuels, but unfortunately these just have the effect of changing the balance between different potential degradation modes arising from the gasification environments.

The project has assessed the potential corrosive effects of deposits formed on coal-fired and coal/waste co-fired gasifier fuel-gas/syngas heat exchangers in ABGC and IGCC systems. This has included determining the ranges of deposit compositions formed on heat exchangers with different fuels and quantitatively assessing the effects of such deposits on downtime corrosion (including the effects of potential preventative measures) and synergistic interactions. These activities have lead to the identification of combinations of fuels, operating conditions and materials that could produce rapid heat exchanger failures due to interactions with the deposits formed during the heat exchanger operation.

The following candidate gasifier heat exchanger alloys were investigated; AISI 316L, AISI 310, AISI 347H, Alloy 800, Sanicro 28, Haynes 160, Esshete 1250, Haynes 556, IN625 and T23. In terms of cost and performance Sanicro 28 appears to be the best choice for evaporative heat exchangers in the range of test conditions investigated.

This report is divided into the following sections:

1. Introduction
2. Aims and Objectives
3. Background
4. Deposit Formation on Gasifier Hot Gas Path Components
5. Review of Trace Element Partitioning in Gasifier Hot Gas Paths
6. Downtime Corrosion Testing
7. Downtime Corrosion and Preventative Measures
8. Synergistic Testing
9. Identification of Safe Operating Window
10. Conclusions
11. Further Work
12. References

The objectives for this project are:

To improve metallic filter media for high temperature applications in aggressive environments.

To design a prototype element for Integrated Gasification Combined Cycle (IGCC) and Air Blown Gasification Cycle (ABGC) applications.

To produce a filter element life prediction model for gasification environments.

Advanced power generation systems, based on gasification, are being developed. Hot gas cleaning technologies for gasification systems offer the potential of a lower cost approach to pollutant control and gas turbine protection, leading to simpler cycle configurations with associated efficiency advantages. The unreliability of the ceramic filter elements used in demonstration trials and the high capital cost of these systems have hindered their application and are factors restricting the uptake of gasification power plants in general. The successful development of a durable metallic filter system for the ABGC would be a major step towards its implementation.

Metallic filter media provide a number of significant advantages over ceramics. In order to realise fully the cost and environmental advantages, it is essential that the systems provide not only efficient contaminant removal but also have the reliability and availability required of the overall system. It is now apparent that reliable, lower cost filter systems can be operated using metallic filter media, provided improved materials selection and advanced fabrication methods are developed.

This project has successfully investigated the performance of a range of candidate materials for the manufacture of filters for use in gasifier (IGCC and ABGC) hot gas paths.

This summary provides information on:

Objectives

Summary

Background

Material Screening

Material Performance Assessment

Modelling and Determination of Operating Constraints

Filter Element Design

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

Further Information

This document is the final report for the project titled 'Metallic Filters for Hot Gas Cleaning'.

Hot gas filtration has not only been adopted as an essential system component in hybrid technologies like the Air Blown Gasification Cycle, but is also being used to remove particulate prior to water scrubbing of fuel gases in first generation Integrated Gasification Combined Cycle (IGCC) plants. The unreliability of the ceramic filter elements in demonstration trials and the high capital cost of these particle removal systems have hindered their application and are factors restricting the uptake of gasification power plants in general. The successful development of a durable metallic filter system for the Air Blown Gasification Cycle (ABGC) would be a major step towards its implementation. Metallic filter elements have potential applications in all IGCC systems and in other industries requiring hot gas cleaning.

This project aimed to identify the optimum materials for the various component parts of metallic filter elements, evaluate candidate fabrication routes and determine likely service lives in gasifier hot gas path environments typical of IGCC and ABGC.

A screening test (Activity A) was carried out to aid the selection of candidate materials for exposure in the main materials test programme (Activity B). The materials chosen for inclusion in the second phase tests were: Haynes D205 EN2691, Fecralloy, Haynes HR160, IN690, Haynes 188, AISI 310, IN C276, Hastelloy X, IN Alloy 800HT, AISI 316L and Iron Aluminide. Activity B tests were carried out in two environments, simulating high sulphur content IGCC fuel gas and low sulphur content ABGC fuel gas. The materials were evaluated at temperatures of 450, 500 and 550°C for the high sulphur gas and at 550°C for the low sulphur gas, for periods up to 3000 hours.

Using the results of Activity B, existing corrosion life prediction models for gasification environments developed at Cranfield University, have been modified and used to predict the expected service lives under operational IGCC/ABGC filter conditions (Activity C). The design requirements for a prototype element for IGCC/ABGC applications have been identified and related to the data produced in this project (Activity D).

When compared to the ABGC gas environment, the IGCC gas environment has been shown to cause significantly greater damage. The damaging effect of deposit coatings has also been demonstrated. The materials tested in Activity B have been ranked in order of degree of oxidation and Haynes D205 EN 2691, Fecralloy and HR 160 have shown the best performance.

The project has provided the basis for new opportunities for the development of metallic filter media in gasification environments. To confirm this potential the manufacture of full sized elements is required together with their demonstration in pilot scale trials and in commercial installations. In addition to coal, biomass gasification can benefit from the improved reliability and filtration performance offered by metallic filters and it is recommended that further work is undertaken to evaluate materials suitable for operating in such environments.

This report is divided into the following sections:

1. Introduction
2. Overall Aim
3. Background
4. Experimental
5. Summary
6. Recommendations
7. Acknowledgements
8. References

Close control of combustion conditions is a prerequisite of efficient operation of power generating plants and for meeting ever tightening emission compliance levels. Often conflicting requirements are placed on combustion systems in limiting individual species such as NO_x and particulate. Recognising this, the project aims to address the following:

Plants retrofitted with low NO_x burner technologies often struggle to meet generator output requirements because of these conflicting needs

Plants fitted with flue gad desulphurisation (FGD) require that the amount of particulate entering the FGD process is minimised, in particular carbon

The potential for significant impact on the costs of disposal of both flyash and FGD by-products

Conditioning of fluegases to improve the performance of electrostatic precipitators is in widespread use. Optimising dose rates for differing fuel and fluegas conditions is problematic

Continuous monitoring of particulate is now a requirement of black fossil-fuelled plant authorisations, but commonly used Opacity based monitors have shortcomings in terms of aggregate emissions which can lead to load shortfall and consequent inefficient use of plant

A number of initiatives aimed at on-line monitoring of carbon in ash have met with varying levels of success. The proposed study would complement this work by potentially using such monitors or indeed using the indications from other systems

The three year project builds on and complements existing work to potentially provide a powerful comprehensive optimiser package to provide maximum collection rate for minimum inputs to the precipitator and assist in the optimisation of combustion. The project aims are met with the following programme:

In year 1: to identify the extent of modification and adaptability of installed systems on selected power plants for application of technologies. Also establish the suitability of alternative monitoring systems and the potential for their use with optimiser packages

In year 1/2/3: GNOCIS will be applied to dust abatement plant for combustion control and optimising particulate. GNOCIS is emissions a neutral network based combustion optimisation that was jointly developed by Powergen and Southern Company Services with collaborative funding from DTI and EPRI

In year 3: system reliability will be established at the nominated site(s)

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Collaborators

The main aim of the project was to develop a nitrogen-stable isotope measurement technique for NOx and to ascertain whether it can be used to determine the relative contributions of fuel and thermal NO_x during coal combustion. The specific objectives were to:

To design suitable substrates for adsorbing NO_x in flue gases.

To establish the isotopic values for fuel and thermally-derived NO_x with samples from test rigs.

To apply the experimental approach to larger facilities and to assess the data obtained for improving existing combustion models.

Suitable substrates for adsorbing sufficiently high concentrations of NO_x from flue gas streams to facilitate the reliable measurement of the nitrogen stable isotope ratios were developed, the substrates encompassing both manganese oxide supported on zirconia (MnO_y-ZrO₂) and iron supported on active carbon (Fe/AC).

This project has established a simple and robust experimental protocol for collecting and determining the stable isotope ratios of NO_x from flue gas. The protocol is much more convenient and rapid than that used in the only other reported study where flue gas NO_x has been sampled for determining isotopic ratios.

This summary provides information on:

Objectives

Summary

Background

Sorbent Development

Isotopic Data for Coals and Chars

Isotopic Data for NO_x Samples

Conclusions and Future Work

Cost

Duration

Contractor

Collaborators

Principle Investigator

Nearly all types of coal gasification based advanced power generation systems under development incorporate hot gas cleaning stages to remove particulates and gas phase contaminants prior to the gas turbine. These hot gas cleaning systems offer significant benefits over conventional wet scrubber clean-up systems. However the development of a continuous fully integrated process, in which gas cooling, sulphur/halide removal, using regenerable sorbents would give substantial benefits.

Systems of this type have a number of advantages: the use of regenerable sorbents produces less waste and reduces the operating cost associated with disposal of classified waste products; the fuel gas cooler is located in a benign environment and can therefore be used to generate superheated steam at supercritical conditions yielding a further improvement in cycle efficiency. In addition, the removal of gas contaminants early in the hot gas path will directly improve the environment for downstream components, e.g. hot gas filter parts. On the basis of the expected reduction in the corrosivity of the fuel gas, components' lives may be extended by up to ten times. This benefit would apply to all types of gasifier, including conventional oxygen blown IGCC's where the introduction of hot gas cleaning would otherwise happen downstream of the raw gas cooler and the hot gas filter, both of which would have to operate in a highly aggressive environment.

This project was targeted at developing such a novel integrated raw gas cooler and sulphur and halide removal process for gasification plant. The desulphurisation process is based on a twin fluidised bed system employing direct solids transfer between adjacent vessels. Halide removal is achieved by means of sorbent injection.

The first stage of the project developed a series of mathematical models for the twin-bed desulphurisation concept. Then a 2-D cold model was designed and manufactured to demonstrate the concepts and the validity of the mathematical models produced. After a series of modifications were carried out and their effects assessed, a twin bed unit was designed and manufactured that was capable of being used initially as a 3-D cold model and then being retrofitted to an existing atmospheric pressure gasifier. The 3-D unit functioned as anticipated as a cold model, demonstrating the expected particle flux between the twin beds, and also showed that there were low gas leakage rates between the two beds. After being retrofitted to an existing atmospheric pressure gasifier, the twin bed unit was used to demonstrate the effect of sulphur sorbent on real gasifier derived fuel gases. Limestone, a well known sulphur sorbent in oxidising atmospheres and reducing atmospheres, was selected to test the effectiveness of the twin bed unit in this project. The twin bed was operated with the outlet gases from the gasifier in one side (absorber side) and with air in the regeneration side of the system. Several operating conditions and variables have been studied in the system: gas velocity, bed temperature. The use of the limestone sorbent in the twin-bed reduced the H2S level in the fuel gas stream under all the conditions investigated.

The twin bed system seems to be a promising technology for a heat exchanger system, due to the good particle flows between the two fluidised beds, and for the reduction in contaminant emissions. However, further work is required to improve the understanding of the twin-bed hydrodynamics, as well as to develop sorbents with operating temperatures that are compatible with the twin-bed concept. Two options for the twin bed system have been suggested as worth pursuing as viable use of this technology in gasification plant design. The first involve a twin-bed gasification-heat exchange system where gas from a gasifier is fed to one vessel and heat is transferred to a second by means of re-circulating solids. The second option is a triple-bed adsorption-regeneration-heat exchange system, where the gas from the gasifier is fed to a vessel and the H2S is removed. Catalyst/sorbent is transferred to a second bed for regeneration, and solids are transferred to a third vessel where heat is removed.

This report is divided into the following sections:

1. Introduction and Background
2. Aims and Objectives
3. Reactor Design
4. Pilot Scale Desulphurisation Studies
5. Halide Removal Studies
6. Scale-Up Issues
7. Conclusions
8. Recommendations
9. References
10. Meanings of Symbols

The overall aim of the project was to develop a novel integrated fuel gas cooler and sulphur and halide removal process for coal gasification plants. Specific objectives were:

To prove the concept of using a twin-bed reactor system is suited to this application.

To assess the performance of available sulphur sorbents in the twin-bed system.

To assess the effect of scale up on the performance of the system and the downstream effects on filter performance, residue characteristics and gas turbine performance.

This project was targeted at developing a novel integrated raw gas cooler and sulphur/halide removal process for gasification plants. This desulphurisation process is based on a twin fluidised bed system employing direct solids transfer between adjacent reactor vessels, with halide removal being achieved by means of sorbent injection.

Within this project a series of mathematical models were developed for the twin-bed desulphurisation concept. Then a 2-D cold model was designed and manufactured to demonstrate the concepts and the validity of the mathematical models produced.

Following on from this, a twin-bed unit was developed from initial design through construction to operation in the hot gas path of an air blown fluidised bed gasification pilot plant. Initially the unit was used as a 3-D 'cold model' for further testing of the twin-bed concept and producing model validation data (particle and gas transfer rates between the twin-beds).

The twin-bed gas cleaning/heat exchanger system shows promise for use on gasification systems, as has been demonstrated by inter-bed heat flux and reduced H2S emissions in all the experiments carried out in the pilot scale hot test rig during this project. However, further work is necessary to understand the complex nature of this process.

This summary provides information on:

Objectives

Summary

Background

Twin-Bed System Reactor Design

Pilot Scale Studies

Scale-Up Issues

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

Further Information

Increasingly, power plants are burning a diverse range of coals (indigenous and imported) under tighter economic and environmental constraints. On-line coal analysers have been investigated in the past, but these are expensive and do not provide a practical solution to the problem. To improve the efficiency of the process, utilities are turning to optimisation packages to assist operation staff. Experience has shown that these optimisation packages can help to optimise the process, but are limited by the wide variation imposed on the system by the constantly changing coal diet. It is therefore desirable to identify the coal being burnt on an on-line, continuous basis to improve the performance of the optimisation packages. Specific objectives are:

To develop an advanced, cost-effective system capable of identifying the fuel burn on on-line continuous basis

To establish quantitative relationships between the 'finger prints' of flames and their corresponding fuel types such that an on-line fuel-tracking system could be integrated into a power station control system

To evaluate the performance of the system for a broad range of fuels at University of Greenwich's Combustion Research Laboratory and at Innogy's 0.5MW Combustion Test Facility

To conduct full-scale demonstration trials on a coal fired power plant

This project aims to develop a low-cost, fuel tracking system for the identification of coals being burnt at any one time. The approach is to extract the dynamic 'finger prints' of the flame and hence the fuel type by processing the output signal of an improved flame-eye using digital signal processing and soft-computing techniques. A prototype will be design, implemented and evaluated first on a combustion test rig under a laboratory environment and then on a 500kW coal fired combustion test facility at Innogy. Quantitative relationships between the dynamic characteristics of flames and their corresponding fuel types will be identified such that the on-line fuel-tracking system could be integrated into a power station control system. Full scale demonstration trials will be conducted on a coal fired power station.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

This document is a report for the project titled 'Once Through Benson Boiler - Vertical Tube Furnace'.

Situated in Henan Province, PRC, Yaomeng Power Plant consists of 4 × 300MWe coal-fired boilers, units 1 and 2 of which, entered service in the mid 1970's. They were of the high mass flux, once through, sub-critical universal pressure ( UP ) type, designed for base load operation to generate 935te/h main steam at 570°C.

From 1992 onwards, after overheating in some of the pressure parts, which led to a restriction of 545°C on the main steam temperature, the maximum output was reduced to 270MWe. The boiler's intrinsic intolerances to load changes, and operation below 230MWe were also problematic, and the prospect of more onerous emissions legislation was thought likely to impose even further restrictions on plant usage in the future, or even bring about its closure.

The scope of work for Mitsui Babcock was centred on the upgrade of the existing boiler, comprising refurbishment of the furnace pressure parts and improvement of the burners, start-up system and control philosophies.

The 168-hour full load reliability test was completed successfully during May, 2002. What made the occasion particularly significant for all concerned was that this was the first time Low Water Mass Flux Vertical Ribbed Tube Benson Boiler Technology had been used for commercial power generation anywhere in the world, a very significant achievement by Mitsui Babcock.

The Performance Guarantee Tests ( PGT's ) were performed by the Thermal Power Research Institute ( TPRI ) during the end of July / early August 2002, and these results and subsequent operation have confirmed the major improvements in the unit. Peak steam output is 1010.3t/hr and maximum continuous output is 954t/hr, both exceeding the guarantee requirements. Peak power output has increased from 270MWe to 327MWe, and in fact the boiler has now been formally up-rated to 310MWe.

The successful completion of this refurbishment is a major milestone in both the development of the technology of once through low mass flow vertical tube boilers and Mitsui Babcock's presence in the refurbishment market in the PRC. Wherever sub-critical once through boilers are suffering load restrictions, intolerances to load changes or high metal temperatures, this technology now offers a proven solution, which also extends to super-critical pressure conditions.

This report is divided into the following sections:

1. Introduction
2. Original Furnace Design and Performance
3. Design of the Refurbished Vertical Ribbed Tube Furnace
4. Boiler Performance
5. Operational Feedback since the Performance Guarantee Tests
6. Future Applications

Mitsui Babcock will provide a new furnace to the Benson 'once through' design as a retrofit to a Chinese power plant. The existing unit is based on Chinese technology and has reached the end of its useful life. The new boiler furnace from Mitsui Babcock will correct short falls and ensure the unit is able to match the best world practice. The new equipment will result in an 11% increase in station output and a reduction in nitrogen oxide emissions by over one third.

The principal aim of the project is to validate the performance of the Mitsui Babcock 'once through' vertical ribbed tube boiler technology. The specific objectives of the project are:

To design new boiler furnace envelope based on vertical ribbed tubes

To establish steam measurement device suitable for utility boiler water walls

To assess the new boiler performance incorporating vertical ribbed tubes

To study oxide growth on the steam side of supercritical boilers in the laboratory

This project will validate the Mitsui Babcock designs for the vertical ribbed tube 'once through' Benson boiler. An assessment of the existing Chinese boiler will address the existing performance of the small bore tubes employed in the furnace walls of the boiler and of the existing corner fired combustion arrangement.

A detailed assessment of new boiler performance will be conducted. The new vertical ribbed boiler furnace tubes will be heavily instrumented and data recorded under different operating regimes (e.g. turndown) to establish the performance. Study tubes will be representative of the whole boiler geometry (e.g. corner, centre tubes etc). Data such as heat transfer, metal temperatures, water mass flux rates, water temperatures, location of boiling, steam temperature profile at the furnace wall outlet and individual tube flows etc will be established.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

The objectives of this project are:

To determine the optimum burner size relative to furnace dimensions

To determine the minimum acceptable pitch between adjacent burners and between the wing burners and furnace side walls

To investigate the effect of interleaving the burner pitches in opposed wall fired plant in order to increase furnace utilisation and improve the turndown characteristics of the plant

To investigate whether biasing of fuel or air across a burner row offers significant improvements in NO_x levels without adversely affecting carbon burnout

Retrofit installations of low NO_x systems are often constrained to some extent by the configuration of the existing plant. These practical constraints can be avoided in the design process for new plant. Factors such as the size, number and pitching of burners are selected to optimise furnace performance in terms of heat input, residence time, corrosion, pollutant formation and economics. The identification of optimum burner size and pitch with particular regard to NO_x emissions and carbon burnout is of significant interest.

The typical burner size employed in existing front and opposed wall fired furnaces, of 300 and 500 MWe, is between 40 and 60 MWth. A non-dimensionalised horizontal, vertical and wall clearance pitch of 2.75d was deemed to be representative of all units studied. However, several units feature tighter pitches.

Comparison of physical model data with predictions from a CFD model of the physical model showed reasonable agreement. Mathematical modelling, for the prediction of the flow field within a multi-burner furnace, can therefore be applied with confidence.

For lower NO_x emission, with no carbon burnout penalty, fewer larger burners are preferable to more burners of a lower thermal heat input. Employing larger burners is also economically advantageous.

Modelling predictions were found to be consistent with previous research by IFRF into the effect of burner scaling technique on NO_x emission. When considering constant-velocity scaling, flame chemistry becomes dominant over mixing as scale is reduced and so a higher NO_x emission results from rapid fuel and air mixing.

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

Collaborators

Background

Furnace Review

Physical Modelling and CFD Validation

Model Definition

Burner Versus Furnace Size

Air Biasing

Burner Pitching

Burner Interleaving

Burner Arrangement and OFA Injection

Conclusions

Fuel gas derived from coal can contain various impurities such as dust and alkali salts, which can deposit on the blades of gas turbines used in cleaner coal systems and lead to increased turbine degradation. It is important to be able to estimate these deposition rates in order to assess different systems.

This project is aimed at:

Providing more accurate models for particulate deposition in gas turbines running on coal derived gases to provide greater accuracy and easier and more rapid use

Extending an existing vapour deposition model to include additional species to better predict corrosion in such gas turbines

Applying the models to example cases of turbines with some representative contaminant levels for both integrated gasification combined cycle (IGCC) and air blown gasification cycle (ABGC) systems

Many cleaner coal technologies, including the various IGCC and ABGC systems derive their inherently high efficiency by coupling a gasification process with a gas turbine combined cycle unit. The coal is converted into a fuel gas that is then used to fire the combined cycle unit. Gas turbines are designed to operate on clean gaseous fuels such as natural gas, whereas the fuel gas derived from coal will contain various impurities such as dust (ash) and also alkali salts. These can cause deposit build-up, erosion and/or corrosion of the gas turbine blades, leading in turn to increased operating costs, both in terms of replacement blades and the associated down times, and reduced efficiency. Conventional IGCC's can clean the fuel gas to very pure levels using low temperature processes. The ABGC, and second generation IGCC's will use hot gas clean up where the degree of alkali removal and dust capture may not be as efficient. This will improve the efficiency of the plant and lower capital costs, but may have deleterious effects on the gas turbine.

To predict the degree of deposition, erosion and corrosion in the gas turbine, it is first necessary to be able to model (i) the behaviour of small particles within the turbine passages, including their impact on the blades and (ii) the deposition rate of alkali salts on the turbine blades. Current models for deposition are difficult to apply and not always physically accurate. Improved models are needed to provide better estimates of the degradation and determine the degree of cleanliness required in coal-derived fuel gases fed to gas turbines.

A computer program will be developed to calculate the behaviour and deposition of small particles in the three dimensional flow fields typical of gas turbines. This program will incorporate the models for both inertial and turbulent effects, which current models can only consider separately

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

The objectives of this project were:

Review UK and worldwide capability in power plant modelling needed to meet requirements

Identify where existing plant models can be applied with benefit to current needs

Identify the benefits and future requirements for a Virtual Plant Demonstration Model (VPDM) for PF and GT/IGCC plant, taking note of potential long term power plant developments

Identify developments needed to produce a VPDM for present and future clean coal technologies and propose a way forward

The project was set up as a potential first step towards a VPDM. It would review the current capability of power plant modelling; it would also look at the future needs and applications, consider how well current models can meet these needs and in particular what further developments are needed. Finally, it would consider the proposed VPDM initiative and consider whether it is the best framework for providing these further developments and if so, what is the best strategy that will enable the UK to produce this VPDM.

The conclusion from the review of existing capabilities is that the UK currently has a strong simulation capability in power generation. Difficulties begin to arise when the range of plant considered in a given study increases, when an equipment change is proposed within an existing study, where operators wish to simulate off-design performance within their own plant or where whole system studies such as economic analyses and cycle optimisation are required.

It is clear from this project that a major collaborative initiative similar to that proposed for a VPDM, is required for the fossil power plant industry. This project has identified the development needs that the collaborative project must meet and it has also detailed a particular integrated software framework that should achieve these needs. Most of the leading organisations in the UK involved in power plant modelling development or use, have indicated that they would like to participate in preparing such a collaborative project.

This summary provides information on:

Objectives

Summary

Background

Potential Users of the Study

Cost

Duration

Contractor

Subcontractor

Background

Conclusions from Reviews

Development Needs

The Way Forward

Conclusions and Recommendations

The objectives of this project were;

To demonstrate that on-line Polycyclic Aromatic Hydrocarbon (PAH) concentration measurements can be used as quantitative indicators of utility boiler efficiency.

To establish the methodology for using PAH detecting instruments to track changes in boiler efficiency and the combustion environment to enable better boiler management.

This being achieved through;

Identification of a candidate instrument for measurement of PAH on-line and modify, if necessary, for use in pulverised coal-fired boiler gas ducts.

The generation of PAH "tracers" under controlled combustion conditions at pilot scale.

To build-up data set of PAH signatures as a function of combustion efficiency and boiler combustion conditions at pilot scale.

To conduct a full-scale boiler test series to supplement pilot scale data.

Development of methodology relating PAH signatures to efficiency and combustion conditions, leading to prototype system.

A literature survey was undertaken on the application of measurements of PAH from power plants as an indicator of combustion performance. In the publications considered it is generally found that there is a correlation of PAH with Carbon rendered useless by the components of the flue gasses.

It was concluded that although the only equipment that is currently commercially available worked well enough at pilot scale, it was simply not robust enough for application at full scale.

The results from the pilot scale investigations showed links between CO emission and degree of burnout and between CO emission and the levels of PAH detected. From this it is concluded that the link between burnout and PAH emission has been established for the rig used.

This summary provides information on:

Objectives

Summary

Background

Experimental Results

Conclusions

Cost

Duration

Contractor

Collaborators

Further Information

Pulverised coal-fired utility plant is under increasing pressure to operate at the highest possible efficiency, while remaining within the limits set by regulatory bodies on environmental pollutants. Because fuel costs are the single largest factor in power station operations, even small savings made here are highly desirable in real terms. It is for this reason that utility companies world-wide are investing in control strategies that maximise the efficiency of boiler operation through the control of important boiler variables in, or as near to, real-time as possible. In the UK, the recent introduction of Integrated Pollution Prevention and Control (IPPC) mandates plant operators to operate at the highest practicable efficiency, and this provides an additional impetus to achieve improvements to operating practice that result in efficiency gains.

Specific objectives are:

To demonstrate that on-line Polycyclic Aromatic Hydrocarbons (PAH) concentration measurements can be used as quantitative indicators of utility boiler efficiency

To establish the methodology for using PAH detecting instruments to tract changes in boiler efficiency and the combustion environment to enable better boiler management

For the best control over boiler operation, it is necessary to utilise easily measured boiler parameters that respond quickly to the changes in the combustion environment. This is usually done by the continuous monitoring of excess oxygen and carbon monoxide concentrations. An additional and valuable measurement of boiler combustion efficiency is the carbon-in-fly-ash concentration. However, this requires an extractive sampling technique, and even the latest generation of carbon-in-ash analysers operates on a semi-batch basis, and so cannot give real-time data.

There is clearly a need for an on-line technique that is robust, relatively simple to operate and maintain, and that gives high-quality validated information on a combustion efficiency. Such a technique could be readily utilised in existing control systems and the development of a real-time combustion efficiency analyser is the focus of this proposal.

This summary provides information on:

Objectives

Summary

Cost

Duration

Contractor

The objectives of this project were:

To evaluate the performance of the original boiler unit and conduct heat flux measurements for input to boiler modelling for a new design.

To develop a non-intrusive device for flow measurement in individual furnace tubes for the assessment of the waterside performance and to prove the new design.

To conduct steam oxidation trials on candidate furnace wall tube materials.

The benefits to the operator, Yaomeng Power Generation Limited, (YPGL) from the project have included:

Increased power output capability.

Improved load following capability.

Improved turndown without fuel oil support.

Improved plant availability and part load efficiency.

Significant savings on fuel consumption.

Reduced emissions.

Reduced auxiliary power draw.

All leading to savings on power generation costs.

This brochure describes the principles used for the Yaomeng upgrade to a Mitsui Babcock Posiflow boiler and illustrates the clear benefits to boilers designed or converted to utilise this low water mass flux, optimised internally ribbed vertical tube boiler technology.

This summary provides information on:

Objectives

Summary

Background

Project Activities

Conclusions

Potential for Future Development

Cost

Duration

Contractor

Collaborators

Clean power technologies have been developed to achieve high efficiencies and low emissions due to stringent environmental regulations. The obvious benefits of clean technologies were adequate while the power market was relatively stable and the plant could operate in base-load condition. However, in the current liberalised power market, electricity prices fluctuate, and thus the operational flexibility plays an important role in the plant profitability.

Powergen and UMIST (Department of Process Integration) have collaborated in a project to develop a means of ascribing a financial value to the operational flexibility (start-up times, ramp rates, minimum stable generation etc) of generating units. The project was partly funded through Powergen (£55k) and partly through support from the DTI's Clean Coal Technology Programme (£50k). This report summarises the Ph.D. study undertaken and presents the results and conclusions.

The basic purpose is to investigate the operational flexibility for power plants generating using coal or heavy fuel oil, in particular looking at Integrated Gasification Combined Cycle plants (IGCCs). The operational flexibility is defined as the ability of the plant to change its operation to respond to the fluctuating electricity prices. The profit that a plant makes is then compared to the profit of a perfectly flexible plant (i.e. instantaneous start-up and shutdown times) to give the cost of inflexibility (Operational Inflexibility Cost (OIC)).

Of the plants studied, the fully integrated IGCC has the best overall thermal performance. The higher the fuel price, the more beneficial it is to operate the IGCC compared with PF plant. In terms of the degree of integration, the fully integrated IGCC has better performance rather than the non-integrated and the partially integrated IGCC plant. The calculated operational inflexibility costs ranged between 0 (for base load operation) and about £2.5M p.a. (for about 55% utilisation) on a 250MW unit.

The overall profitability (excluding fixed costs and capital cost payback) is more dependent on the base capability of the plant than its flexibility. The higher the efficiency of the plant, the less relevant operational flexibility becomes, since high efficiency plant will run base load more often and for longer than lower efficiency plant (if all other factors are equal, such as fuel price, etc). The higher efficiencies of highly integrated IGCCs can offset the cost associated with the longer start up times of the gasifier, due to the increased likelihood of base load running).

This report is divided into the following sections:

1. Introduction
2. Background
3. Theory and Implementation
4. Summary of the Methodology
5. Results
6. Conclusions
7. References

A three year research programme is being undertaken to develop ways of calculating the benefit of plant flexibility as a function of operating regime. This information will be used to evaluate methods for improving plant designs to ensure the optimum trade-off between flexibility and other crucial plant parameters such as capital cost, efficiency and reliability. The main aims of the programme are:

To develop methods for assessing the costs associated with the operational inflexibility of cleaner coal power stations

To develop methods of determining the most cost-effective trade-off between plant flexibility and other plant characteristics such as efficiency

To develop ways of improving the design of cleaner coal power stations

Electricity markets throughout the world are being reformed and deregulated. One result of this is that power stations are required to operate more flexibly, with more starts and stops and more rapid variations in output. As a result there is considerable commercial pressure being put on manufacturers to provide plant that can be operated flexibly, and on generating companies to buy such plant. However, improving the operational flexibility of a plant almost invariably involves some additional expense, either in terms of increased capital costs or a reduction in efficiency or reliability

Powergen UK plc and the University of Manchester Institute of Science and Technology (UMIST) are working together to explore ways in which the costs of plant inflexibility can be quantified. Powergen is contributing its expertise and experience of operating in a variety of liberalised power markets world-wide, whilst UMIST is one of the world's leading centres for the economic optimisation of complex industrial processes.

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The objectives of this project are:

To develop a detailed, written specification defining the required Virtual Plant Demonstration Model (VPDM).

To develop the design of the interface structure and middleware required for the VPDM.

To obtain data for model testing and validation.

To construct the VPDM, test and validate it.

To demonstrate that the VPDM meets the specification and, in particular, that it is possible to link a variety of components and whole plant models across the internet.

To apply the VPDM to a new fossil fuel technology that is of interest to UK plc, which incorporates CO₂ capture.

UK power generation and associated industries are facing growing pressures from ever-tightening environmental constraints, the drive for sustainability and increasing global competition. This provides new challenges and applications for power plant modelling in: new plant development; design and manufacture; plant demonstration and authorisation; engineering support. The recently completed project on Power Plant Modelling (see Project Summary 336), which was supported by the DTI, proposes a new UK power plant modelling initiative: the development of a VPDM.

A future VPDM will provide an integrated software framework which will allow the full potential for whole-plant software modelling to be realised. As a result, UK industry could provide competitive power plant solutions and ultimately zero emission technologies with significantly reduced development costs, risk and very competitive prices. The development of the full VPDM will be split into two phases, each lasting three years.

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The principal aim of the project was to use advanced modelling and testing to extend the size range for which the HCM2S (P23) steel can be fabricated both with and without Pre-Weld Heat Treatment (PWHT). The specific objectives were:

To optimise the fabrication of thick section HCM2S utilising practical and efficient welding processes - Manual Metal Arc (MMA) and Flux Cored Arc Welding (FCAW).

To thoroughly investigate the welding of HCM2S without PWHT.

To model the weld and cross weld mechanical properties of HCM2S both with and without PWHT in order to define cross weld properties.

To demonstrate acceptable weldment mechanical properties.

Consequently to produce fabrication guidelines for thick section HCM2S both with and without PWHT.

This project involved the manufacture of a number of pipe butt welds between HCM2S (P23) and itself - both with and without PWHT, and also dissimilar joints with BS 3064 660 (CMV) and ASTM A 335 P91 respectively, both these alloys representing materials with which there has been identified a potential desirability to join with thick section P23.

It was concluded that acceptable strains were developed during the life of the thick P23 weld for the non-PWHT'd condition to make it a viable option.

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The overall aim of this project is to investigate and develop an integrated, multi-pollutant control approach that targets major reductions in NO_X and mercury emissions from coal-fired plant. The specific objectives of the project are:

To develop a stage-wise NO_X reduction approach that will enable coal-fired utility boilers to achieve a target of 200 mg/Nm3 or better in the most cost-effective manner.

To assess of the combined performance of primary and secondary NO_X control measures including particulate control devices and quantify their impact on flue gas mercury concentration and speciation during coal combustion.

To investigate the suitability of a range of approaches to the removal of mercury from flue gas (combustion modifications, sorbents, additives etc) and to determine the effect of fly ash properties and flue gas chemistry on mercury behaviour.

To develop an integrated multi-pollutant control approach with potential for future application to UK coal-fired power plant (and coal-fired power plant worldwide).

Increasing environmental concerns regarding the use of pulverised coal for power generation continue to drive legislation that limits the emissions of pollutant gases to the atmosphere. The current European Union Large Combustion Plant Directive calls for significant reductions in NO_X, SO₂ and particulate emissions from coal-fired power plant over the next few years. Primary NO_X control measures such as low NO_X burners and air staging and secondary (post-combustion) NO_X control measures such as NOxStarTM or SCR, in combination, should provide the potential for significantly higher overall NO_X reductions to meet the most stringent emission limits in a more cost-effective manner than a stand-alone technology for the same level of NO_X control.

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Foresight's Advanced Power Generation Task Force has recommended that an initiative should be undertaken to produce a Virtual Plant Demonstration Model. The 'Stepping Stones to Sustainability' report of the Foresight's Energy and Natural Environment Panel recommends a priority area for R and D on 'low and close-to-zero emission power generation'; a realistic VPDM will be a key tool in ensuring the UK can successfully develop fossil fuelled commercial plant that delivers this.

The VPDM should reduce the need for full-scale demonstrations of advanced power station technologies, which for large plant typically cost £100's million and should also reduce commissioning times for new plant. It will also help in the development of new technologies and assist in avoiding 'dead-end' developments. Finally, it will be of benefit to existing plant by being able to model new technology upgrades, which could be a major business in some markets where existing coal plant could become marginalised.

Specific objectives are:

Identify the benefits and future requirements for a Virtual Plant Demonstration Model (VPDM) for pf and GT/IGCC plant, taking note of potential long term power plant developments

Review UK capability in power plant modelling needed to meet requirements, through discussions with both participants and UK power industry contacts

Review the worldwide capability in power plant modelling through literature searches, industry contacts, public domain sources

Identify where existing plant models can be applied with benefit to current needs

Identify developments needed to produce a CPDM for present and future clean coal technologies

Organise a UK workshop to discuss and provide guidance on: needs and benefits of a VPDM; current modelling capability; optimum way forward. Invitations to attend will be sent to interested parties in industry, academia and government

Produce a Technology Status Report summarising the work of this project and the output from the workshop. This report will include a recommended strategy for producing a successful VPDM

The UK has a track record of power plant development and operation that is second to none. However the UK has at times fallen down on getting these developments into the market place; the ABGC and some IGCC designs are examples of this. In the case of GTs, new developments have been pushed through into the market place but often they have been accompanied by major commissioning, operation and maintenance problems that have threatened their economic viability. A way round these problems is to have major demonstration programmes but these are extremely costly for large plant and difficult to fund.

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