PURPOSE: To save the amount of steam introduced from the exterior steam generator for heating, by carrying out the heating under pressure and the following pressure release stepwise, and effectively utilizing the steam generated in the pressure-releasing stage for the heating of the raw material under pressure.
CONSTITUTION: At least one intermediate heating vessel 3 to heat a raw material such as wood chip, etc. under a pressure between the atmospheric pressure and the maximum pressure is placed in series between the preheating vessel 1 to heat the raw material under atmospheric pressure and the final heating vessel 6 to heat under the maximum pressure. Pressure feeders 9 to supply the raw material from the low-pressure side to the high-pressure side are placed between the heating vessels and the pressure- releasing and delivery apparatuses 10 to reduce the pressure of the raw material from the maximum pressure to the atmospheric pressure are attached to the downstream side of the vessel 6. The number of the delivery apparatuses corresponds to the number of the feeders 9. The crushers 13 to pulverize the raw material are placed between each of the above steps, and the steam generated by the pressure reduction from the maximum pressure to the atmospheric pressure is made to be introduced by the apparatus 10 to the intermediate heating vessel 3 corresponding to the pressure of the generated steam.
TOITANI MASAO
YOSHIDA KOJI
SATO TAKASHI
