Study On Air Separation Of Integrated Gasification Combined Cycle System

With the continuous emergence of new technologies and new processes,air separation technology has reached the level of the sixth generation of technology.After the completion of China's first demonstration power station Huaneng Tianjin IGCC demonstration power station,it provides a new direction for the study of its characteristics.The air separation system provides high-pressure nitrogen,medium-pressure oxygen and other products to the IGCC power station gasification unit,and its stable operation largely determines the stability of the IGCC system.At the same time,since the large-scale compressors of this air separation system are all driven by motors,the power consumption exceeds 25% of the power generation,which has a great impact on the power supply efficiency of the power station.Therefore,it is determined that the research direction of this dissertation is the stability of air separation system and energy saving.Combined with the actual operation of Huaneng(Tianjin)Coal Gasification Power Generation Co.,Ltd.,the first IGCC demonstration power station in China,the structural characteristics of the air separation system were analyzed,actual production data was collected,and its operating characteristics were studied.Focused on the air separation system for efficiency analysis,mainly to calculate the air separation unit power consumption,oxygen extraction rate,turning operation efficiency,including the efficiency of air compressors,boosters,expanders,high pressure heat exchanger cold loss,low pressure heat exchangers Cold loss.The efficiency of the supercharger was found to be low;the main condensing evaporator in the start-up phase had a slow effusion rate;the oxygen vent valve had a degree of opening that was a waste.Analyze the causes of the above problems,study and propose practical solutions,including the turbocharger carbon ring seal transformation;liquid nitrogen counter-irrigation distillation tower;reduce the pressure of the air compressor;oxygen vent valve fully closed automatically.The above technical renovation program was applied to the air separation system.After comparing the data before and after the technical transformation,it was found that the efficiency after the technical improvement was significantly improved.Themain results were as follows:(1)By reducing the oxygen purity of the air separation system,the total power of the air separation decreased.2070 kW,reduced by 4.92%,and created a profit of 36,000 yuan.The plant electricity consumption rate decreased by about 0.85%.(2)IGGC system will cause economic losses of 146 yuan/day due to oil leakage.Through the reformation of the carbon ring of the booster,the total economic loss of the IGCC unit in 2017 was reduced to 27,800 yuan within 4552 hours.(3)When the IGCC unit is started,the liquid nitrogen is used for the main cooling,which can shorten the start-up time by 5 hours each time and save 180 MWh of electricity.The solution proposed in this paper has certain guiding significance for the problems existing in the air separation system in practical projects.By solving the cost and technical problems,the bottleneck of IGCC technology promotion has been broken through,ensuring that the entire equipment is more economical and the operation is more stable.To reach the goal of promotion and replication as soon as possible.