Analysis Of Operation Characteristics And Optimization Of Heating Parameters For High Back Pressure Heating Units

High back pressure heating realizes the cascade utilization of energy,effectively recovers the energy of exhausted steam and reduces the extraction of high-grade steam.It is widely used in Northwest China.However,in actual operation,no matter how the external parameters change,the back pressure of the unit is basically maintained at about 34 kPa.Therefore,this thesis takes a CZK300 WM high back pressure heating unit as the object,analyzes the operation characteristics of the unit,studies the optimization of heating parameters,and provides reference for energy saving and consumption reduction operation.Through the simultaneous mass,energy balance equation and matrix analysis method,the steam-water distribution equation of the heating unit is obtained,and the variable working condition of the heating unit is calculated based on the Fruger formula.By comparing THA working conditions,rated extraction conditions and TRL working conditions,the absolute error in calculating the power generation and heat rate are less than 1.5%.Then analyze the influence of back pressure and temperature change of return air supply on the performance of the unit.With the increase of unit back pressure,under the same main steam flow rate,the share of steam used to do work decreases,which leads to the decrease of unit power.On the contrary,with the decrease of unit back pressure,the unit power increases.By analyzing the historical data,the heating season is divided into two stages: pure exhaust steam supply and exhaust steam-extraction combined heat supply with the temperature of the water supply temperature of 70 °C.No matter at which stage,the lower the return water temperature of the hot water network,the more steam exhausted steam can participate in the heating,the higher the utilization rate of fuel;Under the premise of satisfying the power generation load,the higher the temperature of the hot water supply,the larger the steam recovery of the recovered steam,the larger the external heating load of the unit,and the better the heating performance of the unit.Finally,the heating model of the heating unit is combined with the heat user and the heating network.The genetic algorithm is used to optimize the operating parameters of the heating system with the total thermal efficiency as the optimization objective function.This paper mainly focuses on the optimization of water operation temperature of primary and secondary heating networks,and gives the optimization results of heating operation temperature under different outdoor ambient temperatures.With the increase of outdoor ambient temperature,the operating temperature of primary and secondary heat network water shows a downward trend,and the underwater drop of secondary heat network is lower than that of primary heat network water;the temperature difference between primary and secondary heating network water supply and return water gradually decreases.