| 摘要 |
<p>Powder or granular material is heat-treated in a closed drum, whereby via or by the pouring of the material a hot air stream, charged if necessary with steam, is pressurized and is intermittently sucked up by a vacuum pump. For this purpose the temperature of the hot air and quantity of steam charge are such that the steam does not condense on the material. In one cycle, involving the pouring of about 10 kg of material, hot air is fed in under pressure for 20-60 seconds and evacuated in 15-30 seconds. To perform the process a conventional vacuum mixing drum (14) is equipped with a device (11, 13) for producing hot air under pressure and/or for charging the hot air with steam, connected with the inlet opening into the drum (14) by a pipe-line (111, 141) in which a valve (112, 142) can also be inserted. Preferably a microprocessor (17) controls the intermittent operation of the valve or valves (142, 152).</p> |
