Research On Waste Heat Power Generation Of Aluminum Reduction Cells' Flue Based On Organic Rankine Cycle

With the rapid development of our country's economy, the contradiction of a relative shortage of energy has become one of the most important limited factors which affect the development of economy and society. Currently, research and development on energy saving technologies of industrial process have important practical significance. In recent years, electrolytic aluminium industry have been developed fast in our country, and the primary production is at the first place of the whole world. Electrolytic aluminium industry has high energy consumption as intensive resource and energy enterprises, and the power saving is its eternal theme.A large number of low-temperature flue emissions from process of aluminium reduction, which heat loss of the flue away trough system generally is 20%-35% by total energy expenditure. Based on the characteristics of the flue gas from aluminum reduction cells, a technology prototype of waste heat power generation for aluminum reduction cells' flue on the basis of organic rankine cycle was proposed, which provides a new thought for energy saving and emission reduction of electrolytic aluminum industry.Based on sufficient investigation for the relative field at home and abroad, with a typical flue system of 200kA series' aluminum reduction cells in a factory, waste heat power generation system based on rankine cycle was built. Relevant mathematics models were established based on the first and second law of thermodynamics. With the aim of ensuring optimal system performance, screening and optimization analysis for working fluids were done, and the most adaptable one is isopentane which was selected as the cycle fluid in the system. The main equipment in the system were selected, which includes that a type of non-standard turbine with low boiling point working fluids is one with single-class single-cylinder condensing steam impulse, the evaporator is spiral fin tube exchanger and the condenser is fixed tube sheet exchanger. And then the structure and working parameters of the main equipment were researched and designed. Through theoretical calculations, the results show that the rated power of system is 600kW, the cycle efficiency is 7.5%, the area of evaporator is 2000m~2, the area of condenser is 450m~2. At last, by programming calculation, the quantitative influences of cycle efficiency, output power, exhaust gas temperature on the evaporation temperature, the superheat degree of the working fluid and the cooling water temperature were researched.The research results will be technical preparation for the exploitation of flue waste heat power generation technology of aluminium reduction cells and provide some guidance for the next step experiment. The technology is also useful for reference of other flue gas waste heat reeovery, and it has important theoretical value and realistic significance for promoting the energy saving and emission reduction in our country.