Study Of High-speed Gas Flowmeter Calibration System

In order to solve the problem that the standard calibration device cannot calibrate high-speed gas flow, this paper designs a new calibration system of high-speed gas flowmeter based on positive pressure principle of standard meter theory, which achieves the rapid, accurate calibration requirements of high-speed gas flowmeter. Through the theoretical analysis of systematic uncertainty and with the help of fluid simulation analysis by the CFD, we can see that the conclusion of this system has broad prospects and feasibility studies.The gas source of this system is provided by the air compressor, which flows standard by gas tank area, and then after the gas tank to the measured surface area. By changing the three pipeline valve opening and gating the measured surface pipeline, realize the flow calibration targets from low-speed to high-speed and confirm the installation location of three standard table and three for calibration table which is determined by the computer fluid simulation technology(CFD) simulation. This system uses PLC-CPU224 as the main controller, the electric control valve as the controlled object, so as to realize the control of pipe flow through the PID algorithm and the open-loop control valve, which contains the determine of closed-loop transfer function and the result of setting parameters provided by the mechanism method and the step response method and the Matlab simulation software of the Simulink. In the process of practical operation, the configuration software MCGS can real-time display the process value of this system and real-time change flow quantitative value and valve opening value.After practical verification of the calibration range, control relative error, uncertainty, the repeatability and stability, we can see that the expanded uncertainty of Calibration System is 0.76%,the calibration range is 10-910 m3/h(the velocity range is 1.4 to 128.7 m/s in the DN50 pipe),and the relative error and relative error of calibration are controlled within 1%, which can be used for high-speed gas flowmeter calibration in the actual situations.