Heat exchange – With leakage collector
Patent
1997-02-20
1999-01-19
Flanigan, Allen
Heat exchange
With leakage collector
1651341, 165157, 165167, 165DIG356, F28F 308, F28F 900
Patent
active
058604707
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a plate heat exchanger comprising a frame with two end plates and between them a package of heat transfer plates with intermediate gaskets, which define flow spaces for at least two heat transfer fluids, and a cover extending around said package.
BACKGROUND OF THE INVENTION
A plate heat exchanger of the above mentioned kind is known through GB 1 500 917. The previous known plate heat exchanger is provided with a cover of rubber material or similar which is moulded around the plate heat exchanger to prevent leakage to flow out to the surrounding atmosphere.
Plate heat exchangers, used at high temperatures, often require frequent gasket replacement, owing to hardening of the gaskets, which deteriorates the sealing ability. Mostly it is the influence from the oxygen in surrounding air in connection with heightened temperature, which causes the breaking down of the rubber material. The choice of heat transfer fluid in the plate heat exchanger is of minor importance. If the gaskets are protected, so that they will not contact the surrounding air during operation, a considerable increase of life at high temperatures can be attained.
One way to achieve this could be to locate the plate heat exchanger in a hermetic container. Such a container could become very expensive, in particular for larger plate heat exchangers. An additional problem with a hermetic container for a plate heat exchanger is that a hydrostatic test and inspection must be allowed. This means that the container must be able to be assembled and dismantled on a plate heat exchanger already tightened.
To embed the package of heat transfer plates, as proposed in GB 1 500 917, does not solve the problem sufficiently. A moulded cover cannot be dismantled in a simple way and besides the cover will assume a rather high temperature and thus aging in the same way as the rubber gaskets. A cover must also function and seal properly despite huge deflection of the end plates during operation, which a moulded cover does not.
SUMMARY OF THE INVENTION
An object with the present invention is to achieve a simple mountable and dismountable cover, which protects the gaskets in the plate heat exchanger from an attack by the surrounding oxygen.
These objects are reached with the present invention, which principally is characterized in that the cover abuts closely towards the end plates and is arranged at a distance from said package so that towards the surrounding atmosphere sealed space is created between the cover and said package.
By covering the parts of the plate heat exchanger, where the gaskets are exposed to the surrounding atmosphere with a cover according to the present invention, it is protected from the harmful influence of the oxygen on the gasket material. The cover can be made so tight that no exchange of gas occurs around the package. The space between the cover and the package can be evacuated or filled with inert gas, such as nitrogen gas or carbon dioxide. As an alternative a continuous flow of inert gas may pass in the space between the cover and the package. The inert gas may also consist of steam. The advantage of steam is its accessibility in most installations.
The invention also refers to a method of protecting gaskets in a plate heat exchanger from being exposed to the oxygen in the surrounding atmosphere after the tightening of the plate heat exchanger, in which the parts of the gaskets of the plate heat exchanger exposed to the surrounding atmosphere are covered by a cover arranged on a distance from the gaskets, and in which the space between the cover and the gaskets is evacuated or is supplied with inert gas.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described more particularly in the following with reference to the accompanying drawings, in which
FIG. 1 shows a schematic side-view of a plate heat exchanger according to the invention,
FIG. 2 shows an end-view of the plate heat exchanger according to FIG. 1,
FIG. 3 shows a cross-section through the end plate nea
REFERENCES:
patent: 2617634 (1952-11-01), Jendrassik
patent: 3099520 (1963-07-01), Hallstrom
patent: 4607684 (1986-08-01), Wiard et al.
PCT Int. Search Report.
Andersson Torgny
Blomgren Ralf
Tagesson Bernt
Alfa Laval AB
Flanigan Allen
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