各因素测量不确定度对锅炉热效率测试质量的影响

Effect of measurement uncertainty on test quality of boiler thermal efficiency

介绍了不确定度分析原理和各因素不确定度分量A类、B类评定方法,建立了锅炉反平衡热效率不确定度分析模型,给出了灵敏系数、合成不确定度的计算方法。在此基础上,以某电厂600MW机组锅炉为计算对象,在消除了因素非完全独立和传统数值扰动计算灵敏系数方法带来的二次不确定度的前提下,研究了各因素测量不确定度对锅炉热效率测试质量的影响;定量给出了各因素测量不确定度对锅炉反平衡热效率测试质量的贡献。结果表明,重要影响因素为,飞灰含碳量Cfh、排烟温度tpy、收到基灰分Aar、收到基低位发热量Qnet,ar、飞灰百分比fh;可忽略因素为,收到基氮Nar、收到基硫Sar、锅炉散热损失Q5。因此,提高重要影响因素的测试精度可显著提高锅炉热效率的测试质量。

The analysis theory of uncertainty and the assessment method of uncertainty factors in type A and type B were introduced.The uncertainty analysis model of boiler thermal effciency was established.Moreover,the calculation methods of sensitivity coefficient,normal combined uncer-tainty and extended uncertainty were put forward.On this basis,a 600 MW unit coal-fired boiler was taken as the example to investigate the effects of each factor＆#39;s measurement uncertainty on test quality of the boiler thermal efficiency.To avoid the secondary measurement uncertainty,the uncertainty factors with incompletely independence and the sensitivity coefficient by conventional imprecise numerical calculus were eliminated.The results indicates that,the parameters having significant contributions to test quality of the boiler thermal efficiency are unburned carbon con-tent in fly ash （Cfh ）,average exhaust temperature （tpy ）,ash content as-received basis （Aar ）,low heating value as-received basis（Qnet,ar ）and fly ash content（？fh ）,in a decreasing order;and the neg-lectable parameters are nitrogen content as-received basis （Nar ）,sulfur content as-received basis （Sar）and surface radiation and convection loss（Q5 ）.Therefore,in order to improve the test quality of boiler thermal efficiency distinctly,it is worthwhile to lower the uncertainty of the significant parameters.