Study On Security Of Water Circulation Under Low Load Operation Of 300MW Boiler

In this thesis a 300MW unit's boiler in Zhangjiakou power station is the object to be studied. The security of the boiler's water circulation under 40% rated load is comprehensively analyzed through the experiments combined with the theoretical calculation. The calculational results indicate that circulation ratio and circulation allowance can be badly influenced by drum pressure; due to low water flow rate in tubes when the boiler is operated under low load, aggravation of heat transfer engendered by the rise of sectional thermal load of evaporator should be prevented. All-around experiments on the temperature of the evaporator wall are performed under 40% load through large quantities of temperature metrical points. The experimental results show that the temperature of the evaporator wall is greatly affected by the distribution of thermal load in furnace, the wall temperature is well affected by the thermal impact in furnace caused by the cease and startup of coal pulverizer, therefore combustion regulating should be carried out before the cease and startup of the pulverizer. Si Junshan (Power Engineering)Directed by Prof. Yan Weiping and Prof. Wang Jianjun...