Research On Technologies Of Piped Natural Gas Ultrasonic Flowmeter In-Service Inspection And Sampling

With the use of a large amount of natural gas, ultrasonic flowmeter is widely used in large-scale natural gas custody transfer metering station for its high accuracy and its big measuring range, which directly affects the national economy and the interests of major companies. Therefore, how to verify the accuracy of measurement as a key issue that must be addressed. In order to improve the testing efficiency of the Piped natural gas ultrasonic flowmeter, this paper is focus on the on-line inspection technology of piped natural gas ultrasonic flowmeter based on comparison of sound velocity.1) As to reduce the existing defects in the current standard of piped natural gas ultrasonic flowmeter testing method, the paper conducted a study on on-line inspection of piped natural gas ultrasonic flow meter based on comparison of sound velocity, established the sound velocity calculation model and analyze the uncertainty of the testing method. A ultrasonic flowmeter on-line testing system software and hardware has been established based on sound comparison testing method.This system connects to the flow meter computer through ethernet, reads quantity of flow synchronously and measures speed of sound, pressure, temperature, signal gain, signal to noise ratio and other parameters, calculates the theoretical velocity through the internal core software, combined with the database to determine the eligibility of parameters.2) Setting up the mobile piston gas sampling device. The device consists of front and rear cover, piston, piston cylinder, guide plate, T-shaped screw gear and the rotating component. Before sampling, turn the rotation handle to the front of the cylinder piston, during sampling, use the inlet pressure to push back the movement of the piston, this device do not need emptying operations before the sampling, it increases sampling efficiency and gas purity3) Creating the high-pressure gas sampling and testing simulation systems. Using this system, pressure resistance and other laboratory testing can be carried out for sampling device to improve its efficiency and device reliability.