Exergy Analysis Of The Combined System Of Compressed Air Energy Storage And Coal Gasification

With the booming development of renewable energy generation and the increasing of the peak and trough of the grid, energy storage technology has gradually become a hot research in the field of energy. Compressed air energy storage gets more and more attention as a kind of great advantage of large-scale energy storage system. But compressed air energy storage technology also has its own shortcomings, the system efficiency is low, and depending on natural gas as fuel does not meet the energy structure of our country, therefore, its development has been greatly restricted. To solve these two shortcomings, this paper proposes a solution:to analyze the compressed air energy storage system by using the method of exergy analysis, to find the parts which have the most exergy loss, and to provide direction for improving system efficiency. Combining compressed air energy storage with coal gasification and using coal gas as fuel, this is in line with the current energy situation of our country.Firstly, the Aspen software is used to simulate a compressed air energy storage system, and exergy analysis method is used. The results show that the combustion chamber has the largest exergy loss of the system. In order to improve the exergy efficiency of the system, we can try to improve the efficiency of the combustion chamber, and the efficiency of the compressor, and the efficiency of the regenerator. However, the method of improving the adiabatic efficiency of the turbine is almost no effect. Secondly, use Aspen to simulate the Shell pulverized coal gasification system, and the exergy analysis is carried out. We can find that coal gasification system has the minimum exergy loss when the oxygen coal ratio is 0.79. Finally, the coal gasification and the compressed air energy storage are combined, and the Aspen is used to analyze the combined system. The exergy efficiency and fuel cost of compressed air energy storage system and combined system are compared. Through the comparison, it is found that the exergy efficiency of the combined system is lower than that of the original compressed air energy storage system, which is about 1.9%, but the fuel cost is significantly lower than that of the compressed air energy storage system. It can be concluded that the combined operation of coal gasification and compressed air energy storage is feasible.