Refrigeration – Processes – Fluid external of refrigeration producing cycle
Reexamination Certificate
1999-08-12
2001-06-26
Doerrler, William (Department: 3744)
Refrigeration
Processes
Fluid external of refrigeration producing cycle
C062S515000, C062S059000, C165S902000, C165S010000, C165S061000
Reexamination Certificate
active
06250088
ABSTRACT:
The present invention relates to a method for cooling a product, preferably in gas or liquid form, using the cooling content of a condensed gas, where the condensed gas is vaporized in a vaporization heat exchanger arrangement and the product is cooled in a product-cooling heat exchanger arrangement, and where both the said vaporization and the product-cooling take place under energy exchange with the vaporized gas. The invention also includes an arrangement for use in implementing the method.
Many large users of gas have this gas supplied in condensed form. When the gas is to be used, it is generally vaporized in an air vaporizer. The use of air vaporizers means the cooling content of the condensed gas is lost. To be able to make use of the cold which is presently lost in this way, flexible and inexpensive equipment is needed which can be used for cooling a number of different products, preferably in gas or liquid form, without them freezing. The equipment must also work without the use of any additional heat transfer medium with low freezing point, which is cooled by the condensed gas and in turn cools the product, because this requires the use of a pump or similar supplying energy to the heat transfer medium, which reduces the cooling content of the latter.
Heat exchangers of the twin tube type having previously been used, see DE-A1-4001330, for cooling a product with condensed gas. The condensed gas in these undergoes vaporization during passage through a central tube, after which the vaporized gas returns to a space of annular cross-section outside this tube and inside a second tubular wall. The product to be cooled is then allowed to pass through an annular space outside this second tubular wall.
In one embodiment described in DE-A1-4001330 the condensed gas is vaporized during passage through a number of straight sections of a central tube. All tube sections are connected in series and forms a single central tube of meander form.
The advantage of a twin tube arrangement is that it is possible to achieve a continuous process, which can be adapted to specific requirements, since the capacity of the arrangement is determined, inter alia, by the length of the twin tube.
Disadvantages of such a heat exchanger of the twin tube type are that the cost of manufacture is relatively high and, at the same time, the volume and the material consumption are high in relation to the capacity obtained. These disadvantages become even more apparent in the above mentioned embodiment which uses parallel-coupled passages for two of the media and series-coupled passages for the condensed gas.
JP 63-275897 discloses an apparatus in which an intermediate thermal medium is cooled in a first heat exchanger comprising only two sets of passages. This intermediate thermal medium is then passed to a second heat exchanger for cooling a product.
Compared to tube-type heat exchangers, plate-type heat exchangers, i.e. heat exchangers made up of a plurality of parallel plates of large surface area which are arranged at a small distance from each other and between them form passages for the various media, provide a substantially greater heat exchanger capacity per unit of volume. The material consumption and the manufacturing costs are also much lower than for corresponding tube-type heat exchangers. It is thus simple and inexpensive to manufacture small plate-type heat exchangers with relatively high capacity.
In our own WO 95/24585, a method and an arrangement are described for cooling a product using condensed gas, which permits the use of simple and inexpensive standard heat exchangers of the plate type. However, it is necessary there to use a plurality of heat exchangers designed as discrete components.
An object of the present invention is to make available a method and an arrangement for cooling a product with condensed gas, without the risk of the product freezing, which permits a continuous process using a plate-type heat exchanger whose capacity can be easily adapted depending on the specific requirements.
The basis of the invention is the realization that this can be achieved with the aiad of a plate-type heat exchanger having a plurality of passages which are located one after the other and are supplied with the media in a certain defined order.
According to the present invention, the special characteristic of a method of the type cited in the first paragraph is that, as the said heat exchanger arrangements, use is made of a combined arrangement comprising a plurality of passages which are in heat-transferring contact with one another and are used for the different media, that at least the passages intended for vaporization of the condensed gas are coupled in parallel between an inlet and an outlet, and that the media are supplied to the passage so that between a passage for the condensed gas and a passage for the product to be cooled there is at all times at least one passage through which vaporized gas flows.
This method permits the use of a simple, inexpensive and compact plate-type heat exchanger arrangement with an easily adaptable capacity for the desired cooling, which can be done without any risk of freezing.
It is preferable for the passages for each medium to be coupled in parallel, and for the common outlet from the passages supplied with the condensed gas to be coupled to the common inlet of the passages for the vaporized gas. A simple coupling together of the passages is achieved in this way.
For efficient heat exchange, it is preferable for the passages to be coupled in such a way that the vaporized gas comes to flow in counter-current direction in relation to the direction of flow of the product.
The combined heat exchanger arrangement is expediently designed in the form of an arrangement with a plurality of column-shaped passages which are disposed side by side and are separated by partition walls with a large heat-transfer surface area. This permits a very compact and efficient heat exchanger arrangement.
The special characteristic features of an arrangement for use in implementing the method will be evident from the attached patent claims.
REFERENCES:
patent: 3587731 (1971-06-01), Hays
patent: 4171069 (1979-10-01), Cornelius et al.
patent: 4370864 (1983-02-01), Wessa
patent: 5220954 (1993-06-01), Longardner et al.
patent: 5435155 (1995-07-01), Paradis
patent: 5511384 (1996-04-01), Likitcheva
patent: 5560222 (1996-10-01), Perron
patent: 5957193 (1999-09-01), Kanada
patent: 6101837 (2000-08-01), Imanari et al.
patent: 40 01 330 A1 (1991-07-01), None
patent: 0 546 947 A1 (1993-06-01), None
patent: 63-275897 (1988-11-01), None
AGA AB
Doerrler William
Pearne & Gordon LLP
Shulman Mark
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