PURPOSE: To obtain effects of dehydration and volumetric flow rate reduction, by vaporizing LPG with sensible and latent heats of a gas obtd. during transportation from a water-contg. holder to a spherical holder and cooling the gas by the latent heat of vaporization.

CONSTITUTION: In the process of pressurizing and transferring a gas from a low- pressure gas holder by a gas compressor in a town gas manufacturing process, an LPG vaporizer 4 is installed between a water-contg. gas holder 1 and a gas compressor 2. LPG vaporized by the vaporizer 4 is added to the system between a gas compressor and a mixer 5. Thus initial cost, power cost, etc. for the gas compressor are largely reduced. Since carburation is performed by using LPG vapor, flow rate control is extremely easy and there is no trouble such as freezing due to local cooling.