Results: Searching for 'Oil & Gas combustion'

The focus of this work is to provide insight into the potential greenhouse gas emissions savings by using natural gas in HDVs, assessing ways to optimise pathways, identifying research and technology innovation opportunities and any implication for the refuelling infrastructure. This has been achieved through comprehensive modelling of natural gas Well-to-Motion (WTM) pathways relevant for heavy duty vehicles (land - on and off-highway, and marine) based on a detailed review of each stage of the WTM natural gas pathway.

Key Findings:

• Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG) have the potential to reduce Greenhouse Gas (GHG) emissions over the well-to-motion pathway by 13% (LNG) - 20%(CNG) for dedicated engines and 16% (LNG) - 24%(CNG) for High Pressure Direct Injection engines per vehicle in the 2035 timeframe in comparison to the reference baselinediesel pathway.
• Cycle specific powertrain technology selection and pathway optimisation are key to providing GHG emission benefits over given usage cycles, with High Pressure Direct Injection and Dedicated gas engines providing the highest benefit.
• Retrofit dual fuel engines have been shown to have high methane emissions, often being worse than baseline diesel powertrains on a GHG emission basis. Effective testing procedures and legislative certainty are required to ensure emissions conformity and facilitate market development
• Providing methane catalysis at real world operating temperatures, i.e. below 350°C, is essential to prevent uncombusted methane making its way out of the tailpipe in powertrains that cannot control methane slip and is a key technology that enables a pathway benefit.
• Employing ‘best practices’ at LNG, CNG and L-CNG stations is a key driver to providing pathway benefits. Vapour recovery systems should be implemented at all LNG stations and the economic proposition and expected utilisation should be aligned. CNG stations should be connected to the highest pressure tier of the grid where possible or employed in combination with a L-CNG station as an easy step to reduce emissions associated with compression, at least until the carbon intensity of the grid is significantly lower than today.
• The economic proposition for natural gas in the HGV fleet hinges upon the fuel duty differential and currently only the long haul segment is economic in the near term. Fuel duty tax stability is key to enable market confi dence to invest in natural gas vehicles and the necessary supporting infrastructure.

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.

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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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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

This report reviews the performance and costs of existing commercial gas turbines and the capability of gas turbines to operate using hydrogen-containing fuel gases. The report was commissioned by ETI to provide background information for a project they will undertake on salt caverns for storage of hydrogen for use in gas turbine power plants.

A wide range of gas turbines are reported by manufacturers to be suitable for fuel gases that contain hydrogen. There is significant experience of using gases that contain mixtures of mainly hydrogen,methane and other hydrocarbon gases, especially refinery off-gases and coke oven gas, which typically contains 50-60%vol H₂. Gases with H₂ concentrations of up to 95% are reported to be used. There is also experience of using syngas from gasification which typically contains 25-50%vol H₂ but the other main constituent is CO, which has substantially different properties to methane.

Use of fuel gas containing H₂ presents some significant technical challenges for gas turbines but also some potential benefits.

The biggest technical challenge is reported to be the high flame speed of H₂, which can result in flashback, although it reduces the risk of blowout. The properties of hydrogen-methane mixtures in gas turbines combustors vary non-linearly with concentration. It is reported that only when hydrogen becomes the main constituent is there a large variation in the laminar flame speed.

Development aspects and assessments of Gas Turbines (fired by methane and/or H₂) are provided, including contemporary OCGT GTs from GE. Additionally, potentially synergistic capture technologies are described

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

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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

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

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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.

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Subcontractor

Background

Conclusions from Reviews

Development Needs

The Way Forward

Conclusions and Recommendations

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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In 2001 an academic study "Socio-technical networks and the sad case of the condensing boiler" (Banks 2001), identified the very low uptake of condensing boilers, despite their apparent cost effectiveness. By 2006, almost every gas boiler installed in the UK was condensing. The market was transformed. This note sets out how that change happened.

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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