Fluid handling – Systems – Multi-way valve unit
Patent
1998-12-23
2000-05-09
Fox, John
Fluid handling
Systems
Multi-way valve unit
137874, F16K 1106
Patent
active
060589744
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a valve for changing the flow direction of a fluid in conduits, which conduct the fluid to and from, respectively, a heat exchanger, wherein said valve comprises a rotatable valve body and a surrounding valve housing consisting of a cylindrical casing with end plates, said valve body having a rotational axis coinciding with the imaginary axis of the cylindrical casing, and four through passages extend through the valve body so oriented that the main flow directions of the fluid are parallel with the rotational axis of the valve body and such that the openings in two through passages, when the valve body is in a first rotational position, are right in front of two openings in the respective end plate and that openings in the two other through passages, when the valve body is in a second rotational position, are right in front of said openings in the end plates.
Heat exchangers used in systems, where cooling water is taken from natural streams, river water, sea water etc, often have problems with clogging. The reason for this is on one hand that silt and particles get stuck in the cooling channels, on the other hand biological growth.
A simple and environmentally-friendly way to keep a heat exchanger decently clean is to backflush it regularly, i e the flow direction is reversed for example one or a couple of times each day. By reversing the flow direction silt and particles, which have got stuck in the inlet region of the heat exchanger, will be flushed out the same way as they entered.
Such a backflushing system is usually constructed of four valves and two tubes, which connect the inlet and outlet conduits. The investment cost for such a system is often rather great in comparison with the cost for the heat exchanger. Backflushing is therefore not used to such an extent as it should, which leads to unnecessary energy losses due to a decreased efficiency of the heat exchanger. The described type of backflushing system has also another drawback, namely the risk for closing or opening wrong valves. With four valves, each having two positions, 16 combinations for the valve positions are possible, which poses high demands on the reliability of the control and supervision systems.
A valve of a similar kind as that proposed by the invention is known for example through U.S. Pat. No. 4,203,469, which describes a valve for use in a cooling system. This valve consists of a rotatable cylindrical body and a valve housing, consisting of a casing and two end plate parts, in which several components substantial for the function of the valve have been integrated. In each end plate there are two tubes extending out for connection of the valve to conduits, and these tubes are oblique in relation to the rotational axis of the valve body. One of the end plates has a sealing washer, which is applied against one end surface of the valve body by means of a spring, and in the other end plate there is an electrical device for rotation of the valve body. This embodiment is best suited for systems with comparatively small tube dimensions and is in several ways less suitable for big valves due to its complexity. With this design the risk for functional disturbances would be very great at use in a cooling water system, where the moist load is very great, especially if sea water is used for cooling, as it is very corrosive. The valve described in U.S. Pat. No. 4,203,469 is also comparatively voluminous, as the four through passages extend in such a way through the valve body that all the four through passages cross the same diameter in the intermediate portion of the valve body. The cross section of the intermediate portion of the valve body has a greatest dimension which is considerably greater than the sum of the diameters of the through passages.
The object of the present invention is to considerably reduce the cost for a backflushing system for a heat exchanger and to provide a system which is simpler to handle.
The cost can be reduced in that four valves are replaced by one and in that the tubing i
REFERENCES:
patent: 4203469 (1980-05-01), Gates
patent: 4867232 (1989-09-01), Dewill
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