Research On Multi-season Adaptability Of Heat Load And Power Load Of 300 MW Class Cogeneration Unit

At present,the phenomenon of abandoned wind and light is serious,the consumption of renewable energy is difficult,the contradiction of heat and electricity during heating period becomes more and more prominent,and the back pressure of air-cooled heating unit in summer is high and the amplitude is large.As 300 MW-class cogeneration unit iss the main peak-shaving unit,this is of practical engineering significance to research on multi-season adaptability of its heat load and power load,and research on the cold-end effect of the air-cooled cogeneration unit during pure condensing condition.In this way,we can effectively solve these problems.This paper first analyzes the heat load adaptability under the three heating modes of cutting the steam of low pressure cylinder,optical shaft heating and high back-pressure heating.For each case of 300 MW cogeneration unit,the case analysis is carried out,and finally the transformation plan is compared.The high back pressure retrofit scheme recovers the most residual heat,with the largest amount of transformation work and highest investment.The residual heat recovery of the optical axis transformation is relatively small.and the transformation workload and investment are relatively small.The low-pressure cylinder cut-off steam intake scheme recovers the least amount of residual heat,and the transformation workload and investment are also the least.The selection of the transformation plan needs to consider factors such as the annual revenue of the unit,the investment and transformation space,the characteristics of the scheme,the heat load and power load of the power plant.Secondly,it introduces two ways to improve the power load adaptability of the cogeneration unit,such as battery energy storage and electric storage heat regulation.Equipping 2×350 MW cogeneration unit of a power plant with a 184 MW electric storage heat system with a total investment of about 160 million yuan.The investment recovery period is expected to be about 4 years.On this basis,a multi-coupled energy storage system is proposed,which combines the energy storage system of flywheel energy storage,battery energy storage and heat storage energy with the cogeneration unit to improve the applicability of the power load of the cogeneration unit.Finally,aiming at the pure condensing operating conditions of the cogeneration unit.a cold storage type cold-end efficiency improvement system is proposed,and a mathematical model is established for the system.A 330 MW direct air-cooling cogeneration unit of a power plant is taken as the research object,and 20%of the exhausted steam is introduced into the cold storage type cold-end efficiency improvement system.And it obtains a new indirect heat transfer area of 221,280 m2 and a total storage tank capacity of 7,500 m3 through a mathematical model,and calculates the back pressure drop of the unit after the cold storage cold-end effect system.The back pressure drop is 6.7?9.9 kPa before the cold water is mixed in the high temperature period,and the corresponding coal consumption drop is 5.36?7.92 g/kWh.The back pressure drop after the spray mixing is 2.2?3.3 kPa,and the corresponding coal consumption drop is 1.76?2.64 g/kWh,the total back pressure drop during the high temperature period is 8.9?13.2 kPa,and the corresponding coal consumption drop is 7.12?10.56 g/kWh.The steam extraction in the low temperature period is halved,and the half indirect air cooling unit is used.The back pressure drop is 1.86?3.2 kPa,and the corresponding coal consumption is 1.49?2.56 g/kWh.Based on the theoretical calculation,the system was mixed with the model experiment.When the cold storage water temperature is 35? and the injection is 1:1,the back pressure drop is the maximum,which is 10.3 kPa;when the cold storage water temperature is 40? and the 1:3 mixing is sprayed,the back pressure drop is the minimum,which is 5.1 kPa.The experimental results show that the temperature of the cold storage water and the proportion of the sprayed water,the back pressure before the spray injection affect the cold storage back pressure drop,the lower the cold storage water temperature,the higher the back pressure before the spray,and the larger the spray ratio,the better the cold storage and back pressure effect.The research results of this paper are useful for the cogeneration unit to achieve thermoelectric decoupling,improve heating capacity and peak-shaving capacity,and carry out cold-end efficiency improvement.