提高主蒸汽流量间接测量计算精度方法的探讨

主蒸汽流量间接测量法已在现代大型机组上广泛采用,但还存在一些问题,使其精度受到限制.为提高主蒸汽流量计算准确性,对其流量构成进行了分解;为解决调节级后无蒸汽温度测点问题,结合试验实例提出了温度替代和弗留格尔公式改进办法;为解决通流面积变化问题,采用试验数据提出了用级组压比变化来表征通流系数变化的新思路,并对流量计算公式进行了误差分析.研究表明,用弗留格尔改进型公式来计算高压缸压力级级组流量误差较小,给出了主蒸汽流量间接测量推荐公式,可供相关电厂借鉴.

Discussion on Method to Improve Accuracy of Main Steam Indirect Meaaurement

The method of main steam indirect measurement,widely used in large capacity units,is restricted by its accuracy due to some problems.In order to raise its accuracy,the flow structure is analyzed to solve the problem without arranging temperature measuring points after control stage.Based on test examples,the improved method of replacing temperature with Friuli Greig formula is put forth.A new concept of depicting flow coefficient changing vs unit stage pressure ratio is presented to solve the flow area variation.At the same time,the error analysis is made for flow calculation formula.The research shows that the error of HP casing stage pressure can be reduced by using improved Friuli Greig.As a result,recommendation formula for indirect measurement of main steam is given for power plant references.