| abstract |
(57) [Summary] [Purpose] To shorten the baking time of the product nitrogen line, reduce the outgas from the pipe, and generate a good quality oxide film on the inner wall of the pipe. [Structure] The raw material air discharged from the adsorption towers 10a and 10b is heated by utilizing the raw material air heater 8 of the H 2 / CO removing unit 5, and the high temperature raw material air is supplied to a cold storage tank 11 for baking. |