Development Of Dynamic Geogas Sampling Device

The dynamic geogas measuring method has been successfully applied in theexploration of metallic minerals, prediction of buried structure and other related fields,however, there are several major problems still remained to be solved atpresent,including lacking a commercialized device specially applied in geogasmeasurement,so we are impossible to comprehend the variable parameters of the gasflow,temperature and humidity during the process of measuring,which bring aboutadverse influence on the accurancy evaluation of the reliability of its measuringresults.This thesis mainly concerned with design and development of the dynamicgeogas sampling device, which can extract geogas in field work at a accuratepumping velocity according to the given flow value, measure the parameters oftemperature and humidity at the sampling site and draw up the dynamic flowcurve,what’s more,storage the flow curve and the parameters of temperature andhumidity to SD card.This device own advantages of compact size, light weight andmore than12hours of continuous operation.It’s proved that this device is a newsampling instrument for the geogas measuring method, which highly improve thereliability and stability of the geogas sampling results.The dynamic geogas sampling device devloped is based on32-bit MCUSTM32F103RBT6. In order to realize accurate control of geogas flow, the duty ratioof PWM wave can be auto-adjusted by the digital PID controller thus controlling therotational speed of DC motor in the micro vacuum pump.the detailed process asshown in the following: Once geogas passes through the flow sensor, the flow signalwill be acquired by MCU, and then compared with the set value, digital PIDcontroller will return a adjustive duty ratio value of PWM wave, thus guarantee theflow stabilitiy of micro vacuum pump.Once sampling time reach to the set value, the vacuum pump will be shut down, then the whole sampling process is over.After installation of the prototype instrument, a comparative experiment wascarried out between the prototype instrument and previous one, and the keyperformance parameters of accuracy and stability was test.the experiment resultshows that the dynamic geogas sampling device can extract geogas accurately andrapidly, fit for field operation. furthermore, all key technical indexes meet thedesign requirements.At last, a research on reliability of geogas measuring method wascarried out, some preliminary conclutions was draw up about the effect of thesampling pressure,environment and sampling time on the dynamic geogas measuringresult.