| 摘要 |
<p>Problem: dust collection in a vacuum/reduced-pressure refining process is conducted using an inexpensive filter without causing damage on and burn of the filter. Solving means: a vacuum/reduced-pressure refining vessel (1), a dry type dust collector (3) using a filter (2) and a reduced-pressure exhaust device (4) are connected sequentially by an upstream-side duct (5) and a downstream-side duct (6), and a gate valve (7) is provided to the upstream-side duct (5). At the time of starting the vaccum/reduced-pressure refining process, non-oxidizing gas is fed into the upstream side of the gate valve (7) and oxygen on the upstream side is replaced thereby substantially. Thereafter, the upstream side is closed gastightly, the gate valve (7) is opened after the closed state on the upstream side is accomplished, and the dust collector (3) is operated. It is preferable that after the vacuum/reduced-pressure refining process the gate valve (7) is closed, only the non-oxidizing gas is fed into the upstream side of the valve to recover the pressure, and then the vessel is opened to the atmosphere, and it is also preferable that after the vacuum/reduced-pressure refining process, an opening part on the duct collector (3) side is closed during the standby till the subsequent vacuum/reduced-pressure refining process is started.</p> |
