In the gas pipeline, the gas⁃solid two⁃phase flow causes erosion and wear on the inner wall of the pipeline, and the erosion wear in the tapered tube is particularly serious. Using the knowledge of computational fluid dynamics, the model was established by CFD simulation software, the fluid⁃solid two⁃way coupling equation was used, and standard k⁃ε model and discrete⁃phase model (DPM) were used for analysis. Investigating the influence of inlet flow velocity, solid particle size and particle mass flow rate on the wear and tear of reducing pipe, and predicting the location of the tapered tube where erosion wear is likely to occur and the optimum flow rate of natural gas. The results show that the inlet flow rate increased from 5 m/s to 25 m/s, the maximum erosion rate of the tapered tube increased first, then decreased and then increased. When the inlet flow rate is 15 m/s, the erosion rate reached the minimum, which is 1.76×10-6 kg/（m2•s）. The particle size increases from 0.5 mm to 4.5 mm, and the maximum erosion rate increases from 4.23×10-6 kg/（m2•s）to 7.56×10-6 kg/（m2•s）, and then gradually decreases to 2.68×10-6 kg/（m2•s）. The particle mass flow rate increases from 0.1 kg/s to 0.6 kg/s, when the inlet flow rate is 15 m/s, the maximum erosion rate increases from 1.76×10-6 kg/（m2•s） to 1.00×10-5 kg/（m2•s）. The erosion wear area is mainly located on the lower wall surface of the tapered tube throat, the lower wall of the tapered tube segment from the 2D region of the throat and the upper wall of the tapered tube segment outside the 2D region, and the erosion wear area of the upper wall surface is approximated by "U" type symmetrical distribution. During gas transfer, the optimum inlet flow rate of gas through the reducing pipeline should be 15 m/s. In order to prevent erosion and wear, it should also be noted that the particle size should not be too small, and the mass flow rate should be controlled within a reasonable range.

In order to compare the difference between the single-stage separator and the two-stage separator, and find out the reasons that the two-stage series separator was not ideal, the two-stage series structure was constructed by using vortex gas-liquid separator as prototype, and through coupling boundary condition, using the Euler-PBM model to establish the numerical simulation model of the two-stage eddy current separator. The simulation results showed that the gas separation effect of the two-stage series separator was better than that of the single-stage separator, but the internal pressure of the two-stage separator was smaller than that of the casing tubing annulus at the corresponding position, which led to the return phenomenon at the vent hole. The outlet of the upper separator had a large pressure difference, the high flow rate and gas-liquid ratio resulted in a significant reduction to the gas separation efficiency of the two-stage separator. When the gas-bearing ratio at the inlet reached 90.0%, the separator failed. The research results had important practical significance for widening the application conditions of ESP, and the research methods had important reference for similar tool simulation.