孔板流量计上游淤积故障诊断与修正研究

Fault Diagnosis and Correction of Orifice Meter with Upstream Water Deposition

在利用流场仿真软件对孔板正常工况和故障工况进行建模与仿真计算的基础上,得出故障所导致的孔板流出系数偏差量与淤积程度的关系式。为达到在线诊断的目的,在传统的孔板法兰取压点后方,再增加一取压点,计算两组差压的比值,再计算差压比值因子k,k反映了淤积所导致流场的畸变程度。通过分析和仿真确定了k所在位置(P3)的最佳选取点,并进一步得出k与故障程度J的经验公式。通过此公式,可以实现淤积故障的在线诊断,进而实现测量值的在线修正。仿真与实验证明:诊断后,能将淤积最严重工况下的测量结果修正到±1%误差以内。并通过实流实验验证了该方法的有效性及其在工程上的实用性。

Based on the modeling of both normal and improper working conditions and the simulation calcula- tion with CFD software,the relationship of deviation value of orifice plate discharge coefficient and deposition degree was derived. In order to achieve the online diagnosis, another detecting pressure point（P3 ）was installed behind the conventional pressure detecting point of flange to calculate two sets of differential pressure, and then to calculate the differential pressure ratio （factor k） , the factor k reflects the degree of distortion of the flow field caused by deposition ;through analyzing the simulation data,the best location of the selection point of the factor k can be determined together with the empirical formula about factor k and failure extent J. Through this formu- la, the online diagnosis of deposition and correction of the measured value can be realized. Simulation and ex- perimental results show that after diagnosis, the measurement result of the most severe conditions can be conected to within ±1% error. The real flow experiments verify the effectiveness of this method and its practicability in engineering.