Analysis of joint operation of air-cooling system and peak cooling device in summer

In view of the insufficient condensation capacity of air-cooling island in the summer, this paper proposed joint operation of air-cooling unit and peak cooling device to reduce the turbine back pressure. A joint operation cooling system can be formed by building a separate condenser room, retrofitting hydraulic pipe and adding a peak heat exchanger device. The influence factors on the air-cooling island condensation capacity are analyzed by establishing heat transfer calculation simulation model of the air-cooled condensers (ACCs) and the peak heat exchanger. The simulation results show that the main factor affecting the condensation capacity of air-cooling condenser and peak heat exchanger is ambient temperature, and the condensation capacity decreases significantly with increasing the ambient temperature. When it is hot in summer, the condensation capacity of original air-cooling system can not meet the demand, therefore, a joint operation scheme is determined for temperature above 10 degrees C: give priority to air-cooling system, peak cooling device as supplement when air-cooling system has insufficient condensation capacity. At the same time, the simulation results show that the joint operation of air-cooling system and peak cooling device can effectively reduce turbine back pressure. In actual power plant, joint operation of air-cooling system and peak cooling device was used at 25 degrees C and 30 degrees C under 330 MW, and the turbine back pressure decreased by 6.7 kPa and 6.1 kPa, respectively. The joint operation system has economic benefits and the investment payback period is 4 years.