Comprehensive Optimization of the Cold End of 1 000 MW Ultra-Supercritical Unit Based on Pump Frequency Conversion

ObjectivesIn the context of carbon peaking and carbon neutrality, the energy saving and efficiency improvement of thermal power units is the key to the low-carbon transformation of the power industry. Moreover, the implementation of cold end optimization to improve the operating economy of the unit is one of the effective methods, Therefore, it is necessary to optimize the cold end system with wide load.MethodsThis paper took the cold end system of the 1000 MW unit of Ninghai power plant as the research object, the calculation model of the wet natural ventilation cooling tower was established, and the corresponding software module was developed, which can realize the coupling calculation of the cooling tower-circulating pump group-condenser-steam turbine unit according to the ambient temperature, humidity and atmospheric pressure data. Taking the actual environmental parameters and operating load as variables, the operation curve of the cooling tower, the comparison between the constant frequency and the frequency conversion operation of the circulating water pump group, and the comprehensive optimization of the cold end of the unit were carried out.ResultsThe maximum energy saving rate of pump frequency conversion is close to 50%. When the ambient temperature is about 31 ℃, the coal consumption rate can be reduced by adjusting the circulating water flow. The lower the ambient temperature is, the greater the coal consumption rate benefit is, the average coal consumption rate can be reduced by more than 2.0 g/(kW⋅h). However, the coal consumption income of different working conditions varies greatly.ConclusionsThe research results can provide reference for optimizing energy conservation at the cold end of the unit.