Exergy Analysis Of Low-temperature Waste Heat Utilization In Steel Industry

Energy is the basis and premise of human survival and development, steel as a base material played a crucial role in the progress of human society. Steel industries worldwide are facing with the contradiction between production and consumption, especially the ones of China. China’s annual steel production accounts for26%of world steel production, more than the total production of the world’s second, third and four biggest steel producers. However, the technical level is low and the energy consumption is huge of China’s steel production. Facing with the status of huge production and energy consumption, it is of great significance to do the energy saving and cost reducing job in China’s steel industry.The energy consumption per unit products of steel in China is much higher than that in Japan, United States and Europe counties. For there is a big gap between the level in China and other advanced countries, and the energy consumption level in small or medium sized steel enterprises is much higher than that in large enterprises, there is a great potential for energy saving and consumption reducing in steel industry of China. The energy efficiency is very low and the energy consumption cost accounts for a big proportion of the production cost of steel production in China’s steel enterprises, so the energy saving and cost reducing work can improve the energy efficiency in steel production process and rise the economic efficiency of steel enterprises effectively.In this thesis, the status of waste heat utilization in China’s steel enterprises is expounded. The principle of work, structure of equipments, production flow, technical characters and actual operating results of the power generation technology of CDQ waste heat recycling, sintering heat recycling, pure burning blast furnace gas and gas-steam combined cycle, TRT residual pressure turbine and converter steam heat recycling are analyzed and researched. The generation links and using principles of waste heat at low and medium temperature is discussed and the specific measures to make CCHP become actual by using waste heat utilization technology at low and medium temperature are exposited. The practical significance of exergy analysis method for energy saving and cost reducing in steel enterprises by analyzing the energy saving analysis methods for waste heat power generation system.The exergy efficiency, exergy loss rate, exergy loss coefficient and other performance indicators are achieved by building the model and analyzing the thermal properties of waste heat power generation system in steelwork with exergy analysis method. By analyzing the variation of the indicators, the performance of waste heat power generation system is evaluated reasonably and the energy saving effects of waste heat utilization in steelworks is analyzed scientifically, and the results provide a good theoretical support and technical guidance for energy saving and cost reducing and economic efficiency improving in steel industry.