| 摘要 |
PURPOSE:To produce a product at the stable degree of concentration by providing a first flow rate controlling valve for controlling the flow rate of feed of a feed step at constant to the inlet of the feed step and providing a second flow rate controlling valve for controlling the flow rate in the outlet of an uppermost step to the outlet of a bottom step. CONSTITUTION:A flowmeter 11 and a flow rate controlling valve 12 are provided to the inlet of the feed step of a cascade and a flowmeter 13 is provided to the outlet of the uppermost step of the cascade and a flow rate controlling valve 14 is provided to the outlet of the lowermost step of the cascade. The flow rate controlling valves 12, 14 are controlled with the flowmeters 11, 13 respectively and control the flow rate so that it is made constant. The flow rate QF in the inlet of the feed step is detected with the flowmeter 11 and the flow rate QF of feed is made constant by controlling the controlling valve 12 with the output of detection. On the other hand, the flow rate in the outlet of the uppermost step is detected with the flowmeter 13 and the controlling valve 14 is controlled with the output of detection and thereby the flow rate QP is indirectly controlled so that it is made constant.
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