Optimization of the optical particle counter for online particle measurement in pressure-changing natural gas.

Abstract

Online measurement of particulate matter in high-pressure natural gas is of great significance to the purification process and safe operation of long-distance pipelines. However, pressure changes in high-pressure natural gas pipelines are complicated. The optical particle counter (OPC) is affected by the change in the refractive index of natural gas, which causes an error of the measured particle size. In order to solve this problem, based on the theory of geometric optics, an optimization model of the aerosol tube spherical window regarding the refractive index was established. This optimization basically eliminates the influence of gas refractive index on the OPC beam characteristics, so that OPC has the same performance under any high-pressure conditions as under normal pressure. The problem of the optical sensor being unsuitable for high-pressure conditions in which it is difficult to be calibrated in atmospheric air is solved, and the accuracy of the online particle test in the high-pressure natural gas pipeline is greatly improved. The influence of window thickness and installation error on the optimization model is analyzed, which provides references for improving the accuracy of optical sensors and application design in higher-pressure environments. Finally, the feasibility, reliability, and accuracy of the method are analyzed and verified by experiments.