Fluid handling – With cleaner – lubrication added to fluid or liquid sealing... – Cleaning or steam sterilizing
Patent
1998-12-16
2000-05-02
Walton, George L.
Fluid handling
With cleaner, lubrication added to fluid or liquid sealing...
Cleaning or steam sterilizing
137241, 137312, 13761418, 13761419, 251331, 2513352, F16K 1104, F16K 1120, B08B 906
Patent
active
060560037
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a double-seat valve, particularly for aseptic applications, having at least two line connections, between which two annular valve seats are disposed coaxially with one another and in series, having two closers, which are axially closable independently of one another and which in the closed state cooperate sealingly with the valve seats and between them enclose a hollow chamber, and having at least one cleaning connection, discharging into the hollow chamber, for introducing a cleaning medium.
Double-seat valves are used particularly in food processing for making sterile products, such as milk products. A leakage hollow chamber between the two closing elements receives any leakage that might occur and the leakage can then be diverted via a special line connection opening into the leakage hollow chamber. To maintain or restore the sterility of the valve under all circumstances, the leakage hollow chamber must be capable of being effectively cleaned and sterilized.
In a double-seat valve, this cleaning can either by done by passing a cleaning fluid or hot steam through the leakage hollow chamber in a state in which it is closed on both sides to which end inflow and outflow lines with additional shutoff valves are provided, opening particularly into the leakage space; or alternatively, one of the two closing elements of the double-seat valve is "vented", to allow the cleaning medium flowing in through the inflow line to flow past it, so that the applicable valve seat is also cleaned or sterilized. A double-seat valve as defined generically by the preamble to claim 1 is known for instance from German Patent Disclosure DE 42 43 111 A1. As its closing elements, the known double-seat valve has two valve plates, which are axially displaceable and can be pressed against two valve seats by means of two shafts nest in telescoping fashion in one another. The valve seats are disposed at a relatively great axial spacing from one another, so that the two valve plates in the closed state between them enclose a relatively large leakage hollow chamber.
Because of the large interior surfaces, it is difficult on the one hand to keep such large leakage hollow chambers sterile. If hot steam is used, on the other hand, the valve plates or even the entire valve housing can heat up to such an extent that chemical changes occur in the substances, such as milk products, located in the adjacent hollow chamber behind the valve plate. This disadvantageous influence on the nature of the substances to be processed is something that must be avoided under all circumstances.
The known double-seat valve has the further disadvantage that the lower valve plate, even in the open state, is always located inside the leakage hollow chamber. The substances to be processed must change their flow direction repeatedly on passing through the leakage hollow chamber, because of the labyrinthine construction. If these substances are for instance intended to pass from the upper pipe neck to the lower one, then they are first deflected radially inward between the upper valve plate and the associated valve seat and then have to flow axially downward and finally emerge radially to the outside again at the lower valve plate. After another short distance axially downward, they are pressed radially inward again between the lower valve plate and the associated valve seat, until they can finally leave the leakage hollow chamber axially at the bottom. It is immediately apparent that these conditions are not optimal on fluidic grounds.
In addition, the short distances between the valve plates and the walls of the leakage hollow chamber or the valve seats limit the maximum size of particles that may be contained in the substance to be processed. For instance, this can set a limit on processing fruit yogurt with whole fruit.
The object of the invention is to disclose a double-seat valve whose construction allows an improved design of the hollow chamber, so that the substance to be processed can pass through in a fluidically favorable way even i
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Benedetti Paolo
Madsen Karsten Schack
Striker Michael J.
Tetra Laval Holdings & Finance S.A.
Walton George L.
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