Gas Turbine Off-Design Condition Modeling And Energy Consumption Distribution Study For Its Power Generation System

On the challenge of the energy shortage,environmental pollution and greenhouse effect,accelerate the adjustment of energy structure in China has become a process necessary for economic and social sustainable development.The gas-steam combined cycle unit is used for electrical network peak shaving,the heavy-duty gas turbine,as the core equipment of the unit,plays an decisive role in the energy structure reform.In the long-term development of heavy-duty gas turbine and its power generation system,many methods to calculate the gas turbine characteristics are proposed,but still need to be improved continuously.To study the internal performance parameters and its characteristics for gas turbine under design/off-design conditions,on the basis of PG9351 FA gas turbine unit,a precise model for heavy-duty gas turbine considering cooling air injection at off-design condition was proposed.The semi-empirical formula was adopted to estimate of turbine specific cooling air mass flow volume,the air mixing impacts on the thermodynamic performance of the turbine,as well as Mach number,attack angle of turbine model at off-design condition modify the gas flow parameters and the speed loss coefficients was considered in this method.The deviation between the calculation results of this model and the manufacturer data are within ±0.4%,this model can be used to analyze the part load characteristic of gas turbine.The efficiency of the high-pressure stage and intermediate-pressure stage still maintained at a high level at the 60% load,but the low-pressure stage decreased by about 1.2%.The influence of turbine expansion ratio distribution,exhaust temperature and output power of Variable turbine’s back pressure were discussed by using the model,obtained the flow parameters inside turbine and its performance parameters as well as its characteristics of each stage,more truly reflected the design/off-design performance in the given operation strategy.In the further work,based on the combined cycle energy saving,applied the precise model for heavy-duty gas turbine on the off-design conditions to the gas turbine unit and its power generation system,applicated the off-design condition theory and the analysis of energy consumption,detailed distribution characteristic from the perspective of design/off-design conditions.The energy consumption level of combustion chamber was the worst on the design/off-design conditions,and the energy consumption of the turbine low-pressure stage decreased rapidly in the off-design conditions,which decreased by about 23.2%.Studied on the energy consumption characteristics at the process,component and system levels,analysed the improvement space of exergy efficiency.Learned the unit’s energy consumption distribution characteristics on the perspective of the design/off-design conditions,analysed the energy saving potential in terms of system system integration,technological innovation and operating strategy.Analyzed the development potential in energy consumption level of the combined cycle and proposed the direction for energy highefficiency using.The research results of the paper established a foundation for the design optimization and efficient operation of the heavy-duty gas turbine and power generation system.And it is of great significance to study the deeper level energy saving and consumption reduction of the heavy gas turbine power generation system.