Modeling and optimization of shutdown process of combined cycle gas turbine under limited residual natural gas

In this study, the characteristics of the shutdown process of combined cycle gas turbine (CCGT) were studied, and an original model for this process was proposed to allocate gas consumption. Based on the model, optimal shutdown scheme was proposed and proven, and optimizing algorithms were developed. It was first found that the total power generation is more relevant with the load-off rates rather than the load-up rates. Assuming residual natural gas volume is 105 m3, the methodology could generate an extra power of 28.41 MW⋅h and an extra profit of 4.79 million Yuan annually. Continuous correction procedure was included in the algorithms to deal with the deviation between actual residual gas volume and theoretical value. An optimization computer program based on the algorithms was developed using ASP.NET and B/S framework. This program was applied to three CCGTs in a power plant in Hangzhou, Zhejiang, China, as a case study. The testing results proven that the obtained optimization scheme is technically effective in the real working condition. Thus, the model and the optimization algorithms were also valid and feasible for potential applications for shutting down CCGT.