Abstract: A fuel conditioning process and apparatus for use where natural gas is compressed by a field compressor driven by a natural gas powered engine. The fuel portion of the compressed raw natural gas is passed through an adsorption vessel containing an adsorbent material capable of adsorbing impurities. The outlet gas from the adsorption vessel is accumulated and mixed for averaging and controlling the heating value of the outlet gas used for fuel. Regeneration of the adsorption material, when employing multiple adsorption vessels, is accomplished by connecting one adsorption vessel to the suction side of the compressor, purified gas from another adsorption vessel in adsorption service is backflowed through the loaded adsorption vessel to desorb the previously adsorbed impurities, the flow of the compressed raw natural gas to the other adsorption vessel is terminated and the pressure within the two adsorption vessels is equalized.