Experimental Study on Reducing Thermal Stress of Steam-Side Oxide Scales by Vacuum Method

doi:10.11930/j.issn.1004-9649.201609039

Abstract

Abstract: Generally, the generation unit is started from cold state by means of pressure method. However, when this method is applied in supercritical boiler, it is inevitable that convective heating surface will be heated dry without steam and, then cooled down with steam. As a result the oxide scales will have to withstand the thermal stress from about 100℃ cooling temperature difference, which can cause the oxide scales flaking. In this paper, the vacuum method is adopted to start the unit. The low temperature saturated steam flows the heated surface of the boiler before ignition, which can effectively avoid the peeling off of the oxide scales during the startup process. corresponding experimental study is carried out in No. 2 boiler in Changsha Power Station Co., Ltd of Hunan CHD and satisfactory results are obtained. The temperature difference of the heating surface is significantly reduced before and after the ignition of the boiler, which effectively diminishes the risk of oxide scales flaking. The method is simple and reliable with no equipment modification needed.

Key words: supercritical unit, boiler, vacuum method, oxide scales, thermal stress, superheater tube

CLC Number:

TK227.7

HE Wenbo. Experimental Study on Reducing Thermal Stress of Steam-Side Oxide Scales by Vacuum Method[J]. Electric Power, 2018, 51(3): 7-12.

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URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.201609039

https://www.electricpower.com.cn/EN/Y2018/V51/I3/7

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