| With the change of social electric power structure and the increase of peak-valley difference of power grid,the utilization rate of coal power plants decreases year by year,which means the thermal economy of the steam turbine at partial load is significantly declined.According to the experience of units running,we report on the operation optimization of the condensing steam turbine as well as its regenerative system at off-design conditions by an experimental study of different governing modes,sliding pressure operation optimization of sliding pressure.By analyzing the relationship between the pressure and heat rate at each load point of the sliding operation based on the experimental research of nozzle and throttle steam distribution modes,boundary point of constant and sliding pressure,as well as optimal initial pressure,are identified.The results could guide the economic operation of the steam turbine.For the constant-speed circulating water pumps with fixed blade,the circulating water flow could only be changed by the number of its running pumps.Based on the experimental data of output correction,considering the unit load and circulating water temperature,we can acquire the optimal back-pressure and the number of operating pumps.Generally,the water level adjustment of the regenerative heater is determined by the terminal temperature difference,however,the corresponding relationship between the water level and terminal temperature difference is uncertain.The water level of the heaters is lower than the design value for actual operation,resulting in a low efficiency,and sometimes even the leakage of pipes.The normal water level is obtained after calculating the economic index,before and after replacing high-pressure heaters,and experimenting on the water level of the heaters.The results of this study have been applied to the actual operation and provide the theoretical basis and feasible method for the optimization of other similar units. |
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