The city gas calorie conversion from conventional city gas (5, 000 kcal/Nm3) to natural gas (11, 000kcal/Nm3) of which dominant source is LNG has been progressing since 1972 by Tokyo Gas Company in order to keep stable gas distribution. It has already completed to 80% and is scheduled at last around Tsurumi factory in which COG is produced. Although the COG occupied only 2% of company's total gas sales, it was to be converted to SNG from the viewpoint of keeping variety for raw material and distribution base.
COG-SNG plant, the first commercial scale plant in the world, consists of purifi-cation process in which oxygen, diolefin and organic sulphur compounds in the feed-stock COG are eliminated and low temperature steam reforming process in which purified COG, LPG and/or off-gas are methanised upon Ni based catalyst. The char-acteristic of this plant is in purification process developed by Hitachi Co. together with Tokyo Gas Company.
