Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-06-18
2001-03-20
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S090000, C210S106000, C210S149000, C210S321690, C210S333010, C210S341000, C210S636000
Reexamination Certificate
active
06203714
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for filtering a liquid, for instance water and more particularly drinking-water for domestic use, which filter device is provided with a filter element.
Such devices have been used for quite some time now for filtering water, and make use of for instance micro filtration and ultra filtration. Particularly micro organisms such as oocysts, cysts (Cryptosporidium, Girardia), bacteria and possibly viruses are filtered from the water by the filter element, so that the filtered water can be used as drinking-water. The first two kinds of micro organisms can be removed by micro filtration, whereas ultra filtration can also (partly) remove the other kinds of micro organisms. The filter elements that are preferably used for this purpose are based on capillary membranes (although other filter elements can be used also), and can or are exclusively provided with an inflow opening or inflow side for the liquid to be filtered and an outflow opening for the filtered liquid, or additionally be provided with one of more connections for discharging concentrate. In the latter case a flow over the membrane surface also arises, which in the classical ultra filtration is called “cross-flow” filtration. After a while such a filter element becomes dirty and cleansing it by flushing the filter element in counter direction is necessary to ensure a good working of the filter element. In the common devices the filter element needs to be removed from the device to that end. The filter element also needs to be disinfected regularly, which up until now has been done by using chemical agents added to the water going through the filter element. In the known devices the filter element cannot be used for filtering the water or the liquid during flushing the filter element and its disinfecting.
SUMMARY OF THE INVENTION
It is among others an object of the present invention to provide a device for filtering a liquid in which the interruption of the normal filter activity of the device during the flushing and disinfecting of the filter element is kept to a minimum. It also an object of the invention to obtain a disinfection of a filter element with a minimal use of chemical agents.
To that end the present invention according to a first aspect provides a device for filtering a liquid, which filter device is provided with a filter element with only an inflow opening or inflow side for the liquid to be filtered and an outflow opening for the filtered liquid, and with a pipe for leading the liquid to the inflow opening or inflow side and a pipe for leading the liquid from the outflow opening or outflow side, the pipe for leading the liquid to the inflow opening or inflow side being connectable to a mains system for supplying the liquid with sufficient pressure to press the liquid through the filter device, characterized in that the device is provided with at least two filter elements placed parallel to each other, a three-way cock being accommodated in the pipe to each filter element for connection of the inflow opening or inflow side of each filter element to the mains system, the three-way cocks being mutually connected by a pipe, with a drain to a sewer or the like, which drain is provided with a closing device, the closing device being connected to a branch point of the pipe, a three-way cock being accommodated in the pipe of each filter element for connecting the outflow opening or outflow side of each filter element to a mains system of a user, the three-way cocks being mutually connected by a pipe. By using two filter elements in the device according to the invention, which are connected to each other in a specific manner by three-way cocks and pipes, the cleansing of the filter elements can be achieved simply by letting liquid, for instance water, flow through them in counterflow by correctly operating the three-way cocks. None of the filter elements have to be taken out of the device to that end. Moreover, for flushing one of the filter elements filtered liquid coming from the other filter element is used.
In a preferred embodiment of a device according to the invention, the pipe has a branch point between the three-way cocks at the outflow side of the filter elements, a pipe being arranged between this branch point and the branch point between the three-way cocks at the inflow side of the filter elements, a closing device, a pump and a heating element being arranged in the pipe between the branch points. In this way it is possible to disinfect the filter elements without removing them from the device, by liquid, for instance water, that at least has a temperature of 65° C., for instance 80° C., so that no chemical agents are necessary. Moreover, during disinfecting a filter element, the other filter element is capable of filtering the liquid, for instance water, in the usual manner.
According to a second aspect of the present invention a device is provided for filtering a liquid, which filter device is provided with a filter element with an inflow opening or inflow side for the liquid to be filtered, an outflow opening for the filtered liquid and a connection for discharging concentrate, and with a pipe for leading the liquid to the Inflow opening or inflow side, a pipe for leading the liquid from the outflow opening or outflow side, and with a pipe for leading away the concentrate from the connection, the pipe for leading the liquid to the inflow opening or inflow side being connectable to a mains system, for supplying the liquid with sufficient pressure to press the liquid through the filter device, characterized in that the device is provided with at least two filter elements placed parallel to each other, a three-way cock being accommodated in the pipe to each filter element for connection of the inflow opening or inflow side of each filter element to the mains system, the three-way cocks being mutually connected by a pipe, with a drain to a sewer or the like, a closing device being arranged in each pipe for leading away the concentrate from the connection, said pipes being connected to the drain via a pipe, a three-way cock being accommodated in the pipe of each filter element for connecting the outflow opening or outflow side of each filter element to a mains system of a user, the three-way cocks being mutually connected by a pipe. By using two filter elements in the device according to the invention, which are connected to each other in a specific manner by three-way cocks and pipes, the cleansing of the filter elements can be achieved simply by letting liquid flow through them in counterflow by correctly operating the three-way cocks. None of the filter elements have to be taken out of the device to that end. Moreover for flushing one of the filter elements filtered liquid coming from the other filter element is used. Moreover, in this way the flow over the membrane surface is not used during the filtration, as is the case in the classical ultra filtration, but to flush away dirt stopped by the filter element. As a result of this so-called “forward-flush” less has to be cleansed in counterflow and so less valuable filtered liquid is used in the cleansing in counterflow.
Preferably the device according to the invention comprises a control means, the control means being connected to a temperature meter and a pressure meter for receiving measuring data therefrom, and the control device being connected to operating means of the three-way cocks, the closing devices, the pump and the heating element for operation thereof. In this way the entire operation of the device including cleansing and disinfecting of the filter elements can take place automatically.
The invention also relates to a method for disinfecting a device for filtering a liquid according to the invention, characterized in that the filter device is provided with at least two filter elements, in that the filter elements are deactivated, the deactivated filter elements subsequently being flushed with filtered liquid in a closed circuit, the filtered liquid prior To being led through a
Bos Meindert
Koenhen Dirk Marinus
Drodge Joseph W.
SepeQ B.V.
Watts Hoffman Fisher & Heinke Co., L.P.A.
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