燃煤电厂耦合熔盐储热调峰特性模拟研究OA

[Objective]To further improve the flexibility of coal-fired power plants,the peak shifting depth is increased.[Methods]In this paper,a 670 MW supercritical primary reheat coal-fired unit is taken as the research object,and a thermal system model is established based on Ebsilon 16.4 to simulate the combination of three heat storage schemes and three heat release schemes.The performances of different combination schemes are evaluated by comparing the indexes of peaking depth,heat storage power,efficiency and thermal efficiency.[Results]Under the heat storage condition,extracting the exhaust steam from the medium-pressure cylinder can significantly reduce the load of the low-pressure cylinder up to 78%.It is necessary to combine with reheat steam to increase the temperature of the molten salt;the electric heating heat storage scheme has the highest heat storage power up to 100.17 MW·h,but the molten salt dosage is larger.In the heat release condition,heating high-pressure feedwater step by step can reduce the amount of steam extraction,and the maximum electric load is increased by 7.4%.The analysis of the combined scheme shows that the scheme of electrically heated heat storage combined with step-by-step heating of feedwater has the optimalperformance,with its whole-process exergy efficiency of 40.71%,thermal efficiency of 42.3%,and peak shifting depth significantly better than other schemes.In addition,the working temperature range of molten salt has a significant effect on energy utilization,and the temperature difference control can reduce the energy loss.The electrically heated heat storage scheme is better than the traditional steam extraction heat storage in terms of energy reuse rate and system efficiency,and is suitable for scenarios requiring fast response to peak shifting.The strategy of heating the high-pressure feedwater step by step when releasing the heat can maximize the flexibility of the unit.[Conclusion]The results of the study provide a theoretical basis for the design and modification of the coupled molten salt thermal storage system in coal-fired power plants,which is an important reference value for new energy consumption and grid stability improvement.