Research On Reduce Exhaust Gas Temeperature Of A Pulverized Coal Boiler

Boilers are the most ordinary pyro-installation. The reduction of theexhaust gas temperature plays a significant role in security, economicaloperation and energy saving for boilers. The study in this dissertation wasbased on the project "Research on Reducing the Exhaust Gas Temperature ofthe Boiler" assigned by China Aluminum Corporation, and performed on No. 2boiler, Heat power plant, Guangxi Branch of China Aluminum Corporation, sothat its high exhaust gas temperature, the problem of slagging and low thermalefficiency should be solved in the research.In the dissertation, at first, the reasons of high exhaust gas temperature andits resolvent were analysed deeply, and by demonstration, finally, an easy andeffective method were developed, which was to reformat low economizer.Based on a lot of literatures and projects, integrated measurement of boiler,integrated thermodynamic calculation and analysis were performed. Therewas a conclusion that the quantity of heat transfer of economizer could play asignificant role in reducing exhaust gas temperature was set up, and academicbasis in low economizer design was accomplished at the same time. Based onreferences and calculation conclusions, spirally finned tubes were choseninstead of bare tubes to compose the new designed economizer. Constructionand major parameters were calculated detailedly, and the conclusion showedthat spirally finned tubes economizer was low height, excellent efficiency inanti-attrition, and outstanding capability in heat transfer, and many advantagessuch as simple structure, low investment, and easy to maintenance. So theintroduction of spirally finned tubes economizer can increase the quantity ofheat flux of economizer, and can produce the reduction of exhaust gastemperature and hot air. Further, burning temperature in boiler decreased, andthe problem slagging in furnace would be relaxed.The new desinged economizer was set up into the boiler. For checking theefficiency, heat balance of boiler was measured before and after reformationrespectively. The conclusion shows that, after reformation, the thermalefficiency had improved as 2.27%, and exhaust gas temperature, hot airtemperature, and burning temperature in boiler had decreases as 40℃, 60℃,and 80℃respectively, and the water temperature in low economizer exitincreases as 20℃. All of these can drive positive effects on the conditions ofboiler, and reduce slagging problem. When the practice of No. 2 boiler is concerned, it can run steadily at a load of 120 to 130t/h in a long-term period.When the economic benefit is concemed, 4,000 tons coal can be saved peryear in one boiler, which would be excellent engineering effect. At present,the achievements have been applied to the other boilers in our power plant.