Quantitative Effect Model of Setting No.0 High Pressure Heater on Exhaust Flue Gas Temperature of Supercritical Once-through Boiler

doi:10.3901/JME.2019.10.185

Abstract

Abstract: At present, the functional relationship between the feed water temperature and the exhaust flue gas temperature of boiler after the installation of No. 0 high-pressure heater of supercritical unit and its influencing mechanism are still unclear. This not only causes obstacles to the performance evaluation of thermal power unit with No. 0 high-pressure heater, but also is not conducive to the adjustment of operation parameters of supercritical unit and the optimization of unit performance. A quantitative analysis model of supercritical unit between feed water temperature and exhaust flue gas temperature of boiler is established, the relationship between the change of feed water temperature of supercritical units and the changes of fuel quantity, exhaust flue gas temperature, SCR inlet flue gas temperature and boiler thermal efficiency and their interaction mechanism are given. Meanwhile, the quantitative influence degree and influence mechanism of boiler fuel quantity and feed water temperature on exhaust flue gas temperature are given respectively. The results show that the flue gas temperature has different sensitivity to the changes of fuel quantity and feed water temperature in different range of feed water temperature. At 75% BMCR and 100% BMCR conditions, when the increase value of feed water temperature is lower than 40℃, the exhaust flue gas temperature of boiler increases with the increase of feed water temperature, afterwards, as the feed water temperature continues to rise, the exhaust flue gas temperature of boiler will decrease due to the dramatic decrease of fuel quantity. At 50% BMCR and 30% BMCR, the change trend of exhaust flue gas temperature and feed water temperature is the same. The conclusion clarifies the influence degree and mechanism of the feed water temperature on the exhaust gas temperature of supercritical units, and lays a theoretical foundation for the performance evaluation of supercritical unit after the installation of No. 0 high-pressure heater.

Key words: analysis model, boiler efficiency, exhaust flue gas temperature, feed water temperature, once-through boiler

CLC Number:

TK221

LI Yong, WANG Yanhong, CAO Lihua, HU Pengfei, NING Zhe, DONG Enfu. Quantitative Effect Model of Setting No.0 High Pressure Heater on Exhaust Flue Gas Temperature of Supercritical Once-through Boiler[J]. Journal of Mechanical Engineering, 2019, 55(10): 185-197.

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