Research On Peak Shaving Capacity Of Cogeneration Unit Based On Absorption Heat Pump

Compared with traditional heating methods,using absorption heat pump to recover the circulating water waste heat can achieve energy cascade utilization,improve energy efficiency while protecting the environment,and expand the unit heating capacity.Therefore,this technology is widely used in cogeneration industry.With the development of our country's economy,the structure of electricity and demand for electricity is changing,and the power system presents the characteristics of an increasing peak-to-valley difference and a marked increase in demand for peak shaving.In order to reduce the peak-to-valley difference of the grid and ease the power consumption of the grid to absorb wind pressure,it is necessary to analyze the peaking performance of the heat-power co-generatort unit of the absorption heat pump.In this paper,a heat-power co-generator unit using absorption heat pump is taken as the research object to study the peak shaving capacity of the unit under different heating loads.Forecasting thermal load based on meteorological conditions,and establishing the absorption heat pump thermodynamic model and turbine variable condition model,analysising the changes of unit heating performance after participating in peak shaving,drawing the condition map of cogeneration units with absorption heat pump.Details are as follows:(1)According to heating data and meteorological conditions during the heating period of the power plant,a heating load forecasting model was established through fitting and parameter correction.After error verification,the model predicts that the thermal load error does not exceed 5%,which can establish parameters for subsequent lithium bromide absorption heat pump modeling.(2)By analyzing the circulation process and heat exchange process of the lithium bromide absorption heat pump,a calculation model was established for each key component of the absorption heat pump,and a thermal calculation program was written using MATLAB software to determine the internal state parameters of the absorption heat pump under design conditions and different Comparing the calculated results with the field operating results under operating conditions,the maximum COP error is only 0.6%,and the model accuracy meets the requirements.(3)Analyzing the application conditions of the Frugell formula,and using this formula to establish a turbine flowing characteristic model.At the same time,establishing the extraction pressure model,the condenser model,and the group efficiency model,comparing the designed data with the model calculation results under different loads of the unit.In contrast,the maximum power calculation error is 3.98%,and the model accuracy meets the requirements.(4)Based on the calculation model and calculation results,the effects of changes in circulating water,extraction pressure,and water temperature on the COP of the absorption heat pump are analyzed,and the maximum load of the cogeneration unit was established based on the limiting factors of the peaking of the cogeneration unit.Calculating Method of maximum load and minimum load of cogeneration units based on the peak load regulation factors of cogeneration units.The conclusion of this paper is as follows: When the extraction pressure rises,the circulating water temperature rises,and the return temperature of the heating network decreases,the COP of the absorption heat pump increases;the auxiliary heating of the absorption heat pump helps expand the peaking range of the unit.With the increase of the heat pump COP,the peaking capacity of the unit gradually increases.When the heating load is 300 MW and the COP is 1.8,the peak capacity of the traditional heating system is 63 MW,which is only 21% of the rated power load.The peak range is small.After the auxiliary heat pump is used for heating,under the same conditions,the peaking range of the unit is 96 MW,and the peak shaving capacity is 53.9% higher than the traditional heating method.With the decrease of COP of heat pump heating coefficient,the peaking advantage of heat pump heating will be reduced,as the COP of each unit decreases by 0.1,the peak shaving range of the unit will drop by about 18 MW.