Heat exchange – With leakage collector
Patent
1997-12-10
1999-06-22
Lee, Leonard
Heat exchange
With leakage collector
165167, F28F 308
Patent
active
059133619
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a plate heat exchanger for heat transfer between a first fluid and a second fluid, in which plate heat exchanger plate formed heat transfer elements are permanently joined together to a plate package and between themselves delimit in alternate interspaces first flow passages for said first fluid and second flow passages for said second fluid, respectively; each heat transfer element comprises two plates abutting against each other and having through-openings aligned with each other; and said through-openings in the plates of the heat transfer elements form a first inlet channel and a first outlet channel through the plate package, which channels communicate with said first flow passage and are closed from communication with said second flow passages, and a second inlet channel and a second outlet channel through the plate package, which channels communicate with said second flow passages and are closed from communication with said first flow passages.
BACKGROUND OF THE INVENTION
Plate heat exchangers in which every plate formed heat transfer element consists of two plates abutting against each other are previously known. A conventional openable plate heat exchanger of this kind is shown for instance in U.S. Pat. No. 4,976,313. Owing to the fact that each heat transfer element comprises two plates it is achieved a safety against getting the two heat exchange fluids, flowing on respective sides of the heat transfer element, mixed with each other within the plate heat exchanger, if a hole would be formed through one of the plates. A leakage of one of the fluids through a hole of this kind makes the fluid in question flowing out into the space between the plates and further therethrough to and past the edges of the plates, where the leakage can be observed. So that the heat exchange fluids during normal operation of the plate heat exchanger shall not flow out into the spaces between the plates in the respective heat transfer elements the plates in each heat transfer element have to seal against each other around their said through-openings. Sealing of this kind can be obtained for instance through welding, brazing or gluing.
Even plate heat exchangers having permanently joined heat transfer elements, each comprising two plates abutting against each other, are previously known. Plate heat exchangers of this known kind, in which the double-walled heat transfer elements are joined through brazing, are shown and described in EP 517 785 and EP 527 875.
A drawback with these known brazed plate heat exchangers is that the double-walled heat transfer elements are brazed together with each other in a conventional manner, i.e. in the same manner as single-walled heat transfer elements in a brazed plate heat exchanger. The adjacent heat transfer elements are, thus, joined with each other by means of a single continuous brazing joint, and if this brazing joint is not close or does not keep tight, there is a risk that the heat exchange fluids despite the double-wall arrangement are mixed with each other in the plate heat exchanger without this being noticed.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a plate heat exchanger having permanently joined double-walled heat transfer elements, which is safer than previously known plate heat exchangers of this kind against mixing of the heat exchange fluids in the plate heat exchanger without this being noticed.
This object is obtained according to the invention by the adjacent heat transfer elements being joined together in each of said interspaces by means of three different and spaced joints, a first joint of which surrounds an area covering the flow passage that is delimited in the interspace as well as the inlet channel and the outlet channel through the plate package, which channels communicate with the flow passage, whereas a second one and a third one of said joints surrounds the one of said inlet channels and the one of said outlet channels, respectively, which constitute by-pass
REFERENCES:
patent: 3099520 (1963-07-01), Hallstrom
patent: 4372375 (1983-02-01), Bond
patent: 4903758 (1990-02-01), Cowan
patent: 4976313 (1990-12-01), Dahlgren et al.
patent: 5193612 (1993-03-01), Stirnkorb
Blomgren Ralf
Engstrom Anders
Alfa Laval AB
Lee Leonard
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