Gas Turbine Requirements for Integrated Gasification Combined Cycle(IGCC) Applications

摘要

In IGCC, the gas turbine has developed into a specialized unit process whose capabilityis critical to achieve requirements of performance, fuel flexibility, reliability and capitalcost. The key challenges for IGCC turbines derive from characteristics of gasificationfuels, gasification operating characteristics, and the level of integration with the processplant. The combustion system needs to achieve superior environmental performancewhile maintaining high performance, reliability and maintainability. The key metrics forevaluating "goodness" of design are reliability, availability, maintainability (RAM),robustness to process variability, response to upsets and trips, time to synchronizationand startup and shutdown automation. Tradeoffs between system physical designparameters and control strategies must be evaluated in terms of overall functionality ofthe IGGC process. Fuel transfers must be seamless and automatic. High availability isachieved from capability of the turbine to robustly co-fire low-calorific synthesis gas withsupplementary fuels. Low calorific fuels provide special challenges to control systemdesign. Variability in syngas composition, temperature and pressure need to becompensated for in terms of control strategies and hardware configuration. The highhydrogen content of syngas must be fully considered in terms of fuel system design.Potential future carbon constraints on fossil power will necessitate carbon capture thatis most effectively performed on a pre-combustion basis. This will result in gas turbinefuels that consist of 90% or higher hydrogen. Gas turbines and combustion systems areready for this challenge as has been demonstrated in their application in chemicalprocess plants having upwards of 95% hydrogen. The paper session discussesexperience with syngas, how current turbines are configured for IGCC configurationsand plans for further improvement.