Research On Operation Optimization Of Heating Unit Under Complex Heating Mode

With the improvement of people’s living standards,in the cold winter,especially in the north,people have increasing heating demand,which leads to the increase of heating demand in China,and will also bring great challenges to China’s heating capacity.In recent years,the state has issued policies to encourage the technical transformation of cogeneration units.The purpose is to fully recover the waste heat of the power plant and further improve the external heating capacity of the power plant.However,the change of outdoor ambient temperature in the whole heating season is complex.For the initial heat exchange station of the power plant,if heating is carried out according to a fixed heat exchange network,it will lead to low heating efficiency.Therefore,this paper proposes a heat exchange network connection mode that can be adjusted according to the change of ambient temperature,so as to minimize the heat exchange loss in the whole heating season.Using this heat exchange network can not only reduce coal consumption and pollutant emission,but also reduce heating cost.Firstly,the application of step heating in heat exchange network is analyzed in this paper;The mathematical model of heat consumption calculation of heating unit is introduced;The simulation model of the target unit is built by using ebsilon software,and the error of the relevant parameters of the simulation model is verified respectively.The results show that the maximum error is 0.98%,and the errors of the model are within the allowable range,which can meet the accuracy requirements of unit energy consumption and operation optimization in the follow-up study.Then it analyzes the change law of heat consumption rate,introduces the heat method,actual enthalpy drop method and work capacity method,points out their existing problems,and then puts forward the cost method to calculate and analyze the economy of heating units.Then the sensitivity analysis of the impact of the changes of unit price,unit heat price and unit price of standard coal on the total economic benefits is carried out.The calculation results show that the sensitivity of unit price to the total economic benefits is the largest,the unit price of standard coal is the second,and the unit heat price is the smallest.According to the heating experience in previous years,four representative ambient temperatures are selected,and Aspen is used to design the heat exchange network.Different heat exchange network connection modes are proposed for each temperature,and the calculation and analysis are carried out.The advantages and disadvantages of heat exchange network are evaluated by efficiency and loss,and the optimal connection mode of heat exchange network under different ambient temperatures is obtained.According to the connection modes under different ambient temperatures,an adjustable heat exchange network which can change the connection mode according to the opening and closing of the valve is proposed.The free switching of different connection modes is realized through the opening and closing of the valve,which greatly improves the practicability and economy.Finally,in order to study the influence of the heat exchange network on the operation of the heating unit,the heat exchange network and the required steam are substituted into the heating unit model for simulation calculation.The operation of the unit is evaluated by heat rate,steam rate and power generation.Through calculation and comparison,the optimal heating scheme under different heating conditions is selected,which provides a reference for the actual operation of heating units,which is of great significance.