A strategy for improving efficiency of hydrogen co-fired combined cycle power plants via fuel preheating adjustment

초록

Considering the high cost of hydrogen, enhancing the efficiency of hydrogen co-fired combined cycle power plants(CCPPs) is particularly important. This study proposes a strategy to improve the efficiency of hydrogen co-fired CCPPs by adjusting the extraction water flow in the fuel preheating process. An integrated model of a 400 MW class CCPP, coupling the gas turbine, bottoming cycle, and fuel preheating system, was developed. Through this model, it was found that the maximum efficiency point of CCPPs can be derived by adjusting the extraction water flow in fuel preheating system. Based on this, the extraction water flow conditions that yield the maximum efficiency of hydrogen co-fired CCPPs were derived. Compared with the case of maintaining the extraction water flow at design-point, the strategy of adjusting extraction water flow achieved a maximum efficiency improvement of 0.089%p under the constant TIT conditions. Furthermore, this strategy was also feasible under constant power conditions, achieving a maximum efficiency improvement of 0.098%p. These results show that the efficiency of hydrogen co-fired CCPP can be improved without additional equipment, simply by adjusting the operating conditions of fuel preheating system, which is expected to provide a practical pathway toward power-sector decarbonization.

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