科研之友
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摘要
Industrial furnace is a huge energy consumption industry in China, which accounts for about 1/4 of the total energy consumption in China every year. In the increasing shortage of energy and environmental pollution today, the energy saving and emission reduction is very urgent for the industrial furnaces and kilns. The production of industrial furnaces is a process of collaborative works of different equipments and processes, including the conversion and transfer of material and energy between various systems. Therefore, the analysis of material flow and energy flow for industrial furnaces and kilns is the basis of realizing high efficiency and low emission. The general method is mainly analyzed from the perspective of energy or waste heat utilization of the furnace products, and the industrial furnace is not regarded as a total system to investigate the material flow and energy flow status. In this paper, based on the node calculation method and starting from the whole system of industrial furnaces, a mathematical model of matching material flow and energy flow was established, and the energy balance of different parts of a typical industrial furnace was obtained. Meanwhile, the exergy loss of furnace system was studied by the second law of thermodynamics, and the key parts of furnace energy saving were found. The material flow and energy flow of 3 200 t/d typical cement kiln were analyzed and calculated by this method. The results show that the heat loss of cement kiln mainly includes high-temperature loss and low-temperature loss. The high-temperature loss is mainly the heat loss of the kiln′s walls and the carbon heat loss of unburned coal, accounting for 6.84% and 1.95% respectively, and corresponding to the loss of exergy as 4.17% and 2.59% respectively, which has a few energy-saving potential. The low-temperature heat loss includes the heat loss of flue gas at the tail of kiln and sensible heat from the clinker out of the cooler. The heat loss of AQC furnace and SP furnace accounts for 3.06% and 6.19% respectively, and corresponding to the loss of exergy as 1.26% and 1.45% respectively, which is still worthy of utilization. According to the different reasons for high temperature and low temperature heat loss, in this paper, the energy saving potential of furnace and kiln was evaluated and some new technologies, such as advanced heat insulation of furnace wall, oxygen enriched calcination, and low temperature waste heat utilization were proposed, which could further reduce the coal consumption of the kiln. In addition, some new technologies are recommended to reduce the electrical power consumption of the equipment, such as the use of high-efficiency fans and permanent magnet motors, combined with the technology of surplus steam-driven fan and energy-saving management, which is expected to achieve the goal of zero power consumption of clinker sintering system.
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单位高温气体动力学国家重点实验室; 中国科学院大学
