PURPOSE: To improve the yield of hydrogen and to stabilize the operation of a crude hydrogen generating section by blowing hydrogen-rich purge gas from units for purifying hydrogen by pressure swing adsorption into a gas mixing nozzle before the methanol-water evaporator of the hydrogen generating section.

CONSTITUTION: The pressures of methanol 1 as a starting material, water 2 and a condensate 15 are increased with pumps, and they are mixed in a pipe, preheated to a temp. below the evaporating temp. with a preheater 4, and fed to a mixer 5, where the mixture is mixed with purge gas recovered from units 10 for purifying gaseous H2 by pressure swing adsorption. The resulting liq. mixture contg. methanol mixed well with water is evaporated in an evaporator 6, heated to the reaction temp., and introduced into a reformer 7 to produce crude gaseous hydrogen contg. CO2, CO, moisture and a little methanol. This reformed gas is cooled with the preheater 4 and a gas cooler 8, and moisture and methanol are separated as a condensate with a separator 9. The remaining crude gaseous H2 is passed through the units 10 to increase the purity. Purge gas used in the regeneration of an adsorbent in each of the units 10 is stored once in a surge tank 12, compressed with a compressor 14, and blown from the nozzle of the mixer 5.