Development Of Calorific Value Measurement Of Exhaust Gas Collecting Device

With the rapid increase in the volume of natural gas,in order to protect the fairness and justice of the natural gas trade,China should be in line with the international trade mode,shorten the gap with the international advanced measurement technology.In this situation,the paper mainly developed a set of high accuracy gas calorific value measurement standard device of the exhaust gas composition detection system,used to collect natural gas after burning.The main works are as following:1.The reference and summary of the domestic and foreign relevant literature data for the discontinuous combustion gas calorific value measurement standard device are summarized,and the technical index and the overall design scheme of calorific value measurement of exhaust gas collecting device are determined.2.The overall structure of the exhaust gas collecting device is described.The device adopts a piston cylinder with high precision and high machining precision.Using Solid Works 3D software to design the structure of the device,the mechanical structure design of the device is analyzed and the optimum design scheme is obtained.And the hardware of the control system is selected.3.Design of the hardware and software of the control system for the exhaust gas collecting device.In the design of hardware system,the circuit principle diagram choses to design and verify,and the components are selected to integrate chip.In the design of PCB,the circuit board is designed based on the realization of the function,which makes the hardware system has good anti-jamming capability.In the design of software system,the software system is divided into measurement module,control module and communication module by using modular programming method.The modules are added to the test system and fault handling mechanism to ensure the stability and security of the software system.4.Each sensor in the device and pipeline is calibrated and the exhaust gas collecting device and drying device are designed and tested,the experimental analysis is carried out.The gas mass flow meter is with a range of 0~1L/min and the uncertainty is better than 0.1%.The device is tested for air tightness test and repeatability test,and The influence factors,such as machining error,pressure,leakage of piston cylinder,temperature and distance measurement error,are analyzed.the experimental results show that the device is running well,the repeatability is better than 0.3%,and the extended uncertainty is 0.78%(k=2).