| 摘要 |
<p>961,320. Filters for liquids; automatic control of filters. KOLSCH-FOLZER WERKE A.G. March 21, 1961, No. 10277/61. Heading BID. After filtration, backwashing is only momentary and is followed by discharge of residue by inflowing unfiltered suspension. During filtration, suspension inlet valves 11 to 13 to a filter 1, Fig. 1, are open, filtrate valve 20 is open, and valve 22 in a by-pass 21 preferably remains open. Filtration is under pressure, with a counter-pressure on the filtrate side. On attainment of a predetermined residue thickness, a valve 17 in a residue-discharge pipe 16 is opened and valves 11, 12 partly closed. Consequently, filtrate flows back through the filter tubes 6 and detaches the residue 6a therefrom. Almost immediately afterwards, filtrate valve 20 is closed. Valves 11, 12 are now opened wide so that incoming suspension forces residue through pipe 16. Finally, valve 17 is closed, valve 20 opened, and valves 11, 12 opened to their normal extent. In Fig. 2 (not shown), a pressurized-water inlet pipe is connected between filtrate outlet 18 and valve 20, and the by-pass 21, 22 is provided around a valve 32 on the pressurized-water pipe. Valve 32 is opened briefly instead of valve 20 being left open briefly for the backwashing step. The appropriate valves may be actuated in sequence by pneumatic control apparatus set in operation by reduction of flow through a flowmeter in the suspension inlet pipe. Alternatively, hydraulic or electric valve-actuation may be used. Both pressurewater and filtrate may be used for backwashing ; compressed air may be admitted to the water or filtrate pipe or to portion 3 of vessel 1 to assist backwashing, or compressed air may be used alone.</p> |
