Liquid purification or separation – With alarm – indicator – register – recorder – signal or... – In effluent conduit
Patent
1992-05-28
1994-07-12
Drodge, Joseph W.
Liquid purification or separation
With alarm, indicator, register, recorder, signal or...
In effluent conduit
210 94, 210 961, 210194, 210424, 210745, B01D 2132
Patent
active
053285980
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for the filtration of contaminated liquids, in particular water which is contaminated by oil or oil containing substances, comprising a filter zone through which the liquid passes and in which contaminants are to be held back, for example by adsorption, and also a monitoring device arranged at the outlet side of the filter zone which on inadequate action of the filter zone switches off a pump conveying the contaminated liquid to the inlet side of the filter zone and/or blocks off a discharge line adjoining the outlet of the filter zone.
A corresponding device is described in GB-A-16 01 671. In this known apparatus the pump is arranged at the outlet side of the filter zone and the monitoring device reacts to the suction side pressure of the pump, i.e. to the pressure of the liquid between the outlet of the filter zone and the pump inlet. As the throttling resistance of the filter zone increases with increasing contamination the suction side pressure of the pump reduces with increasing contamination. On falling below a corresponding threshold value the connection between the outlet of the filter zone and the pump inlet is then blocked by means of a shut-off valve.
It is known from GB-A-717 479 to supply a contamination binding agent to a contaminated liquid which can then be subsequently held back together with the contamination it has bound in a filter zone through which the liquid passes. A monitoring device for the residual contamination of the cleaned liquid is arranged at the outlet side of the filter zone. This monitoring device reacts to the scattering of a light beam passing through the liquid which varies depending on the degree of the residual contamination and controls the supply of the contamination binder, in such a way that an excessive residual contamination is avoided.
The object of the invention is now to enable a particularly economical operation of filtration devices and in particular an ideal exploitation of the capacity of the filter zone.
This object is satisfied in accordance with the invention in that a circulation valve controlled by the monitoring device is provided which can be switched over between a throughflow position in which the outlet of the filter zone is connected to the discharge line, and a circulation position in which the outlet of the filter zone is connected to the suction side of the pump, the pressure side of which is connected with the inlet of the filter zone and in that in operating states in which the monitoring device registers an exceeding of a threshold value for the residual contamination of the liquid emerging from the filter zone the circulation valve can be changed over by the monitoring device to circulatory operation and, when the circulatory operation leads a lowering of the measured value for the residual contamination beneath the threshold value, can be switched over again into the throughflow position.
Through the possibility of switching over to circulatory operation, if necessary, in which the liquid to be cleaned is fed back again from the outlet side of the filter zone to the inlet side of the latter, and thus must pass anew through the filter zone, account is taken of the fact that different operating conditions can arise depending on the nature of the monitoring device in which the monitoring device registers an excursion above the threshold value for the residual contamination although in actual fact no impermissible residual contamination is present. Here the invention makes use of the recognition that these "apparent residual contaminants" only respectively occur for limited time intervals in contrast to "true residual contaminants". Accordingly the true contaminants cannot be directly distinguished by the monitoring device The true contaminants are distinguished in that on exceeding the threshold value of the residual contamination a change-over is first made to circulatory operation and check is made whether the degree of the registered residual contamination sinks beneath the threshold value in a relati
REFERENCES:
patent: 4235718 (1980-11-01), Lopez
patent: 4563272 (1986-01-01), Yoshida et al.
patent: 4622133 (1986-11-01), Furono
patent: 4698151 (1987-10-01), Ozawa et al.
patent: 4840730 (1989-06-01), Saxena
Gehringer Andreas
Lohrl Volkhard
Drodge Joseph W.
Firma Fluid Team Automationstechnik GmbH
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