Errors of Manometric Co₂ Sorption Experiments On Coal Caused By Accuracy Of Pressure Sensor

The accuracy of supercritical CO₂ sorption determination on coal is important for estimating the CO₂ sequestration potential of coal bed using CO₂ injection into deep unminable coal seams. Based on the CO2 density change and CO2 sorption data of three selected coal samples, this paper investigates the effect of pressure-sensor accuracy on measurements of CO2 adsorption isotherms on coals with manometric equipment. The characteristic density-change of CO2 in proper pressure range determines a greater influence of pressure error on CO2 adsorption data on coal. The sensor accuracy has significant influence on Excess sorption increment of CO₂ on coal in medium pressure (7-12 MPa), and on CO2 Excess-sorption isotherm at medium-and high pressure. The medium pressures with a greater CO2 density-change at a constant temperature in the sample cell are probably inevitable. A lower experiment-temperature will results in a greater measurement error of the sorption caused by pressure sensor accuracy. The pressure sensor accuracy may result in the less reproducibility and repeatability of CO2 adsorption on coals at medium- and high pressure, and negative sorption increment and even negative adsorption