Off-Design Model Building And Its Appliaciation For GTCC

The introduced F class gas turbines under market for technology policy in China are unavoidably facing performance degradation after several years’ service. Through regression analysis on operation data, a mathematical model for gas turbine was obtained. Combining with the triple-pressure level heat recovery steam generator(HRSG), the power and efficiency sensitivity of component degradation for gas turbine combined cycle(GTCC) power plant were studied at various IGV(Inlet Guide Vanes) degrees. For the MPCP1-M701 F GTCC, the results show that the linear relation exits between the component degradation level and the change of power and efficiency in the same IGV degrees; the sensitivity of turbine degradation are about three times as great as that of compressor degradation. With the decrease in IGV degree, the power sensitivity of compressor degradation and turbine degradation declines; the efficiency sensitivity of compressor degradation increases while that of the turbine degradation decreases. The measures of changing IGV degree and adjusting turbine exhaust temperature control line are proposed to improve the GTCC performance. This study provides reference to the energy conservation of GTCC power units.As the rising proportion of natural gas in China energy structure, Combined Heat and Power(CHP) systems based on GTCC are expected to have wide applications. A CHP system based on GTCC, which combines triple-pressure HRSG and extracts steam from the intermediate pressure turbine exhaust, has been proposed. A stage-stacking method has been used for compressor, and a stage-by-stage model including blade cooling has been adopted for the turbine. Off-design characteristics of different efficiencies and indictors, such as electrical power, total energy utilization efficiency and heat to power ratio, at various steam extraction ratio values, have been studied. Besides, the effect of steam extraction ratio, at different IGV degree, on those efficiencies and indictors has also been discussed. Maximum and minimum steam extraction ratio values at different IGV degree have been calculated. For the MPCP1-M701 F units, the results show that, as gas turbine load decreases, all efficiencies decrease and its rates increase, electrical power and heat load decrease with linear relation, heat to power ratio increases and its rate increases too; as steam extraction ratio increases, all efficiencies increase with linear relation, electrical power decreases while heat load increases with linear relation, heat to power ratio increases and its rate increases.With capacity and exhaust temperature of ground gas turbine improving, supercritical steam parameters in HRSG is expecting to be applied in the engineering. Based on the heat transfer differential equation, one dimensional mathematical model for supercritical pressure HRSG has been proposed and verified by experiment data. The effect of pressure distribution on efficiencies, mass flow rates and product of heat transfer coefficient(U) and heat exchange surface(A) has been studied. The results show that, when the UA remains constant, exergy efficiency can get 0.33% improvement at the optimum point.