Improving Peaking Load Performance by Unit Absorption Heat Pumps Optimization

Presently the cogeneration unit utilizing lithium bromide absorption heat pumps to take heat from low quality waste heat sources has been upgraded in North China to increase the heat capacity of the unit and improve the unit efficiency. Yet operation of the cogeneration unit with full loading of the heat pumps often leads to high power output under high heating load condition and poor peaking load performance. In this paper, optimization of the heat pumps is proposed to improve the peaking load performance of the cogeneration unit. The model of 300MW cogeneration unit with lithium bromide absorption heat pump configuration is built-up using GateCycle simulation code, and the unit performance under various heat pumps operation modes is analyzed. The change of unit minimum peaking load performance and total economic benefit of the unit under same heating load condition, and corresponding operation compensation cost for the peaking load loss are calculated. The calculation results show that for the 8 heat pumps configuration the optimum heat pump Scenario is 4 heat pumps out of operation condition. Under the same heating load the minimum peaking load can be decreased by 28.49 MW in maximum and the total operation economic benefit is reduced by 7.478 thousand Yuan/h under this optimum condition, which leads to the equivalent operation compensation cost for the peaking electricity loss of 0.2625 Yuan/kWh. These data can provide a baseline for power plant to make competitive bidding in the upcoming power ancillary service markets.