Research On Gas Flow Standard Facility For High Temperature Gas And Characteristic Analysis Of Flowmeter

The gas flow standard facilities by master meter,as a secondary transmission standards are widely used in flow meter calibration and verification because of its high efficiency,low construction costs.With the widespread use of gas flow meters,the demand for its verification or calibration is also increasing rapidly.In some industrial production conditions,the measured gas medium,such as steam,exhaust gas and so on have a higher temperature,while the flow meter used in the normal temperature test conditions rather than high temperature.It makes a great influence on the result and characteristic of meters using at higher temperature while calibrating at room temperature.In order exploring this kind of influence,this paper designs a set of gas flow calibration facility for high temperature condition,and the flow characteristics of the flowmeter with high temperature medium are studied.The main work of this paper is listed as follows:(1)The working principle and hardware structure of the high temperature gas flow calibration facility are introduced,including the master meter system composed of the roots flowmeter,the high-pressure gas source and the decompression device,the gas heating device,the temperature and pressure transmitters and the PLC;(2)The simulation of the temperature field of medium in the pipeline through the heating device is carried out.The reason of the uneven distribution of the temperature field is analyzed,and an optimization scheme is put forward which installing the flow regulator to rectify the flow field in the pipe.The same simulation experiments to verify the effectiveness of this program is also carried out;(3)According to the verification process,a human machine interaction program based on LabVIEW and PLC-based control system are developed to achieve the monitoring and verification process,temperature and pressure data acquisition,data processing and report generation and so on.This facility has been put into practical utilization,the stability of the flow rate is 0.30%(k = 2),the pressure stability is better than 1.94% and the temperature stability is better than 2.66%,the flow rate stability is better than 0.44%.(4)The ultrasonic flowmeter is selected as an experimental instrument to study the flow characteristics under high temperature medium,and the flow rate measurement of the flowmeter is calibrated by the speed correction method.The results of the calibration experiment show that the ultrasonic flowmeter measurement results are influenced by the medium temperature and pressure conditions,and the error is up to 16%.The error correction method can reduce the error to less than 4%.