Research Of Numerical Calculation Method And Tackling Measures Of Thermal Deviation Of Large-Capacity Boiler

With the development of the electrical industry, the installed capacity of the thermal power generating unit is augmenting increasingly. The generating units of 300MW and 600MW have been the main ones in the power network. Whether these generating units′operation is superior or not will have a great influence on the dependability and efficient performance of the power network operation. The reliable operation of the superheater and reheater that are the key components of the large-capacity power station boiler is very significant for the whole units without doubt. With the enlargement of the installed capacity, the overheating and tube rupture of the boiler superheat system frequently happen because of thermal deviation, which seriously affects the safe and economy operation of generating plant.On account of the related fact above, research into the causes of the thermal deviation, the calculation method of the thermal deviation and the wall temperature are greatly important. But most researches into the causes of the thermal deviation often are thrown into some a side, few carry out an all-round and systematic theoretical analysis, and many manufactures calculate the wall temperature popularly according to the old standard method about the heat calculation of the Soviet Union, this method is suitable for the last boiler unit of small capacity and low parameter, but as to large-capacity and high parameter power station boilers today, it will bring some problems inescapably. So this dissertation establishes reasonable steam throughput distribution calculation pattern, thermal calculation pattern and wall temperature calculation pattern, abandon the defects of the old calculation method and take the progressive calculation method appropriate to the technical application in order to reflect accurately the distribution condition of the outlet steam temperature and wall temperature of the heat-exchanger surface. At the same time, according to the causes of the thermal deviation, the measures or schemes to decrease the thermal deviation have been put forward.This dissertation puts the calculation patterns established into practical use, taking the thermal condition of MCR load of the SG1025t/h subcritical pressure concurrent boiler of the Shi Dong Kou Power Plant as an example, and gives a profound analysis on the main causes of the thermal deviation. The calculation results of the thermal deviation prove it appropriate that the calculation method is taken, for the results can accord with the factual thermal deviation condition. So this dissertation can provide a certain reference value and practical direction for the optimum design of the heat-exchanger surface and the accident analysis.