Study On A Gas Supply System Of Rossini Gas Calorific Value Measurement System

Rossini type gas calorific value measurement system is used to determine the heat energy released by completely burning unit amount of gas.During operation,gas and oxygen are brought into the burning chamber with a certain volume ratio,where gas is burned at a constant pressure.Heat released during combustion is obtainedby determining the temperature rising of the heat absorber medium.Calorific value is tracde to the two SI units,i.e.mass,and temperature by the gas calorific value measurement system.Since that a high measurement accuracy can be obtained by gas calorific value measurement system.Rossini method is usually used for national gas calorific value standard device.In this thesis gas supplying and mass weighing techniques for a Gas calorific value measurement system was studied.The main works are as following:(1)Development of gas supplying system.Base on the study of the working principle and key techniques of a Rossini typeGas calorific value measurement system,the main technical parameters for gas supplying system were determined.Designing works have been completed,including the general design scheme,gas supplying peline design,type-selection of the components.After processing,assembling and adjustment agas supplying system was in working.The results of air tightness and system performance tests show that thechara cteristics of the gas supplying system developed can satisfy the requirements of the calorific value measurement facility.An on-off switch unit for the gas supplying system was developed which is based on LabVIEW and NI DAQ module.By using the on-off switch unit,gas supply pipe can be switched on or off automatically according to medium temperature.Additionally,igniting tests were performedwith burning system together,andthe optimal mixing ratio of the methane,oxygen and argon was determined,so that a stable combustion can be reached.(2)Study on the gas mass measurement based on the PVTx method.A gas mass calculation model for the PVTx method has been presented,and the measurement uncertainty for this it has been evaluated.The results indicate that the measurement uncertainty of this method is better than 0.18%.Then,a comparativetest was carried out between the PVTx method and double-balls weighingmethod,the deviation values between these two methods are less than 0.3%,which indicates that the PVTx method is feasible forgas mass measurment.(3)Study on the gas stateequations.Based on the theory of gas state equation,three actual gas state equations for alkane was selected to be compare,A method to evaluategas state equation was presented,and a computer program was developed with JAVAlanguage to perform numerical calculation for gas state equation evaluation.The calculating resultswere compared with NIST data.Among the three equations,the relative error of BWRS is 0.04%,with BWRS equation a relative high precision data can be obtained in predicting thermodynamic properties of methane.