Integrated Analysis Of Air Separation Units In Oxygen-enriched Combustion Power Generation System

The choice of air separation units(ASU), especially the matching and optimization of air separation units and oxygen-enriched combustion unit, has great influences to the power supply efficiency, output power and net generating cost of the whole oxygen-enriched combustion power generation system. These effects are caused by ASU’s energy consumption. So it is of great significance that the study of ASU optimization and the relationship between configuration and the energy consumption to reduce the CO2capture cost of oxygen-enriched combustion generation system.This paper has made a deep research on the influence factors of ASU’s energy consumption and the recycling of waste energy, taking the300MW oxygen-enriched combustion power generation unit as an example and the ASU as the main research object and relying on the theoretical research and the simulation modeling. Based on comparative study of different ASU processes, it’s proved in theory that the ASU of the external compression, not making argon and high purity nitrogen gas process is suitable for oxygen-enriched combustion. Using this optimal match, oxygen making power consumption of ASU is0.352kWh/m3and service power rate of ASU can reduced to19%.Then, considering the oxygen supply of300MW generators, an air separation units model with the software Aspen Plus are built, researching the way to raise oxygen-enriched combustion generator integral net power efficiency through the simulation.The simulation result shows that ASU has lots of waste cold and heat, and the paper has put forward two methods to recycle these energy:making waste nitrogen cycling in the condenser as the cold source, it will lower the condenser pressure effectively and raise turbine absolute internal efficiency, and the net power efficiency was raised by0.25%; using the waste heat produced by air compressed systems to heat the boiler feed water, it saves energy evidently and the net power efficiency was raised by0.63%compared to the common oxygen-enriched combustion generator. Combined with the power generation practice, comprehensively considering the daily oxygen demand and peak-valley price, this paper puts forward six different oxygen supply and electric supply ways to reduce the ASU energy consumption. Taking an300MW oxygen-enriched combustion generator as object, comprehensively considering the investment cost and operation cost, based on the proper estimates of relevant parameters, oxygen generation cost in each case is calculated respectively. The result shows that, through the optimal match, ASU energy consumption can be reduced by2.1%, and the net power efficient of oxygen-enriched combustion generator can be raised by0.8%.Through the energy integration and power supply mode integrating between the ASU and oxygen-enriched combustion generator, finally the overall net power efficiency of the generator set can be increased by1.68%, and the technology has a notable energy saving effect.