Electric Power ›› 2017, Vol. 50 ›› Issue (10): 97-103.DOI: 10.11930/j.issn.1004-9649.201701084

• Generation Technology • Previous Articles     Next Articles

Cause Analysis on and Solution to Abnormal Reheat Steam Temperature of Boilers

ZHAO Zhenning   

  1. North China Electric Power Research Institute Co., Ltd., Beijing 100045, China
  • Received:2017-01-17 Online:2017-10-25 Published:2017-10-30

Abstract: Abnormal outlet reheat steam temperature is a common problem for boilers. Facing the issues of low pressure and low specific heat capacity of reheat steam, its temperature-sensitiveness to changes of absorbed heat and the evident negetive effect on the total unit efficiency due to the desuperheater water amount reduction, the reasons why the arrangement of lean-margin reheating heat exchange area and the flue-gas-side temperature adjustment on the reheat steam temperature are adopted in the boiler design are anlyzed. They are also found to be the root causes of why the reheat steam temperature is so easily disturbed by the minor operation changes such as coal type, the boiler combustion mode, the exhausting steam temperature of turbine high pressure cylinder. Targeting at these factors, the phenomena, laws, judgment methods and the corresponding measures to solve theabnormal reheat temperature problem are discussed and summarized. to It is emphasized that the right order to solve this problem should be comprehensive analysis, combustion adjustment, and reheater retrofit. The advantages and disadvantages of three methods-adding serial radiant reheater, adding serial convectional reheater and adding parallel convectional reheater, are discussed in order to meet the strict demands of reheater retrofitting. By comparison, it is concluded that the method of adding parallel convectional reheater works better than the other two. The study result may provide references for sovling the abnormal reheat temperature problemes.

Key words: coal-fired power plant, boiler, reheat steam temperature, convectional reheater, wall type radiation reheater, safety, economy

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