The Thermal Analysis And Optimization Design Of Low-Pressure Economizer Used For Boiler Exhaust Heat Recovery

Boiler exhaust has always been one of the most important heat loss. High exhaust gas temperature of each power plant has long been a common problem, especially in a period of plant operation which the operating parameters deviate from the design parameters, or changes in coal and other reason. This not only affects the thermal power plant economics, the safe operation of the air pre-heater also lay hidden. Therefore, in order to improve safety and reliability of plant operation and to achieve energy saving, we must find ways to reduce exhaust gas temperature. Low-pressure economizer installed in the boiler tail is a use of flue gas waste equipment. It reduces the temperature of the exhaust and coal consumption, recycle heat back into the boiler heat system to improve the operation of the economy, so it is widely used in power plant waste heat recovery. This paper analyzes and compares a variety of ways how to reduce exhaust gas temperature and the heat loss, and focuses on the actual application of the low-pressure economizer system used to reduce exhaust gas temperature.This paper studies the low-pressure economizer system, analyzes various economic parameters, gives the optimal design model. Meanwhile, As a power plant installed low-pressure economizer for example, at a given condition of exhaust gas temperature, according to the optimal design model, this paper calculates the optimal heating surface layout and structural parameters of fin tube. Then according to the method of local economy calculation, it analyzed the thermal system which installed low-pressure economizer, calculated and compared the whole plant thermal efficiency and coal consumption rate under the modes layout. What is more, it discussed the influence of design and operating parameters on the heat transfer coefficient. In addition, this passage researched one of H-type finned tubes which widely used in low-pressure economizer, analyzed the heat transfer process by numerical simulation and obtained the variation of hear transfer coefficient and flow resistance of H-type finned tube side with gas velocity and fin space which support a reference for project.