| 摘要 |
<p>In a new process for the manufacture of furfural, a "pentosan-containing raw material acidified or not, is heated to a temperature T 1 by admitting steam through valve 2 while the valves 3 and 4 are closed. During the very short heating process, the steam condenses, thus increasing the moisture content of the charge. Then, valve 2 is closed and a leak valve 3 is opened so as to produce a steady small flow of product vapour by gradual depressurisation. This causes a slow drop in temperature. When in this fashion a suitably chosen temperature T 2 is reached, the leak valve 3 is closed to terminate the first "gradual depressurisation". If at the end of this period no more furfural was obtained, the digestion is completed by opening valve 4 to discharge the residue. If, however, furfural was still obtained, the reactor is reheated and submitted to another "gradual depressurisation" period.</p> |
