Particulate And Vapour Deposition In Gas Turbines Fired On Coal Derived Gases: Project Profile

Abstract:

<p>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.</p> <p>This project is aimed at: <bl> <li>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</li> <li>Extending an existing vapour deposition model to include additional species to better predict corrosion in such gas turbines</li> <li>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</li> </bl></p> <p>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.</p> <p>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.</p> <p>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</p> This profile contains information on the project's: <bl> <li>Objectives</li> <li>Summary</li> <li>Cost</li> <li>Duration</li> <li>Contractor</li> </bl>

Author(s):

DTI