Study on the Interchangeability of Low Calorific Value Coalbed Gas Blended with Dimethyl Ether Mixture and Natural Gas

China's coalbed methane resources are very rich, but the utilization rate is extremely low, especially low calorific value coalbed methane, because its methane concentration cannot meet the requirements of direct utilization, it has to be discharged into the atmosphere, causing huge energy waste. Dimethyl ether (DME for short), as a multi-purpose clean and environmentally friendly energy source, has received more and more attention in recent years because of its broad market prospects as a new clean fuel in replacing diesel or liquefied gas. By blending dimethyl ether, the combustible components in low calorific value coal bed methane can be increased, and the utilization efficiency of low calorific value coal bed methane can be improved. In this paper, the AGA and Weaver index methods are used to comparatively study the interchangeability of mixed CBM with dimethyl ether and natural gas, which provides a theoretical basis for the promotion and use of blended CBM. The results show that neither AGA flashback index nor Weaver flashback index can meet the requirements of interchangeability, the increase of dimethyl ether blending ratio has no obvious improvement on the flashback phenomenon, the increase of the dimethyl ether blending ratio can improve the lifting phenomenon, but the yellow tipping phenomenon is also going serious, and it suggests that the blending ratio of dimethyl ether in coalbed methane should be controlled at 80%, but attention should be paid to prevent flashback.