US2655351A - Temperature control for heat exchangers - Google Patents

Description

Patented Oct. 13, 1953 UNITED sT fr s PATENT OFFICE 2,655,35l v a TEMPERATURE" consent i on HEAT GEQ? .s.

PontusLarsson Hytte,' Lund, Sweden, assigner toAktiebolaget Separator, Stockholm,

Sweden, acorporation of Sweden,

Application April 13, 1949; ,SerialNo. suit In Sweden April 14, 1948 1 -This invention relates to heat exchangers of the type having a-thermomete or thermostat extending, into a fluid channel formed by throughflow openings in the plates, for use in controlling the temperatures of the treated liquid. More particularly, the invention relates to an improved exchanger of this type in which the thermometer or thermostat performs its function more effectively than has been possible heretofore under some operating conditions.

In plate heat exchangers as commonly made, the plates are provided with throughflow openings which, when the plates are assembled, form channels for the heat exchange fluids. These openings are usually rather large in order that the channels shall have a suificient throughiiow area for all throughput rates. It has been found, however, that when small throughput rates are used, for example, in the treatment of cream, these large openings are disadvantageous in that a liquid level is formed in the openings which is about midway between their top and bottom edges, or lower. This is an inconvenience when the temperature of the treated liquid is controlled by means of one or more thermometers or thermostats extending into the channels, because the thermo-responsive device may not then extend down into the liquid sumciently or at all and therefore provides a false indication or control of its temperature.

According to the invention, this inconvenience is avoided by providing in the channel formed by the openings of the plates, and behind the seat of the thermometer or thermostat, a plate provided with a throughflow opening smaller than those in the other plates, which smaller opening is positioned at or near the level of the upper edges of the other openings. In this manner, the level of the liquid is forced to rise until it reaches this smaller opening, so that the channel is completely, or nearly completely, filled with liquid.

The accompanying drawing shows by way of example one embodiment of the invention. In the drawing, the single illustration is a vertical sectional view of a plate heat exchanger constructed in accordance with the invention.

The heat exchange plates I, 2, 3, 4, 5 and 6 are held vertically in parallel assembled relation at opposite sides of a thicker plate I (a so-called coupling plate). The plates are separated from each other and from end sections 8 and 9 by sealing gaskets I 0 extending along the peripheral portions of the plates. At their upper portions, the plates are provided with throughflow openings II forming a channel I2 through which the liquid 4 Claims. (01. 25744 51) under-treatment flows in the directionof the-arrows I from alternate plate interspaces situated to the left of the plate I to alternate plate interspaces situated to theright of i it. The other liquid, that is, the heatingor cooling medium,- flows through the plate interspaces intermediate these alternate ones. The intermediateinterspaces are sealed from channel I2 by gaskets I3 and communicate with a separate throughflow channel (not shown) offset laterally from channel I2, in accordance with the usual practice. It will be understood that the lower portions of the plates are provided with another pair of separate throughflow channels for the respective liquids, to complete the separate paths for the flow of the two liquids through the exchanger. As the arrangement of these other throughfiow channels, and the manner of securing the gaskets in position, may be conventional, they require no further description or illustration.

The apparatus as illustrated is provided with only a small number of plates corresponding to a. low throughput rate. Accordingly, if each of the plates were formed with the usual opening I I, the channel I2 would be filled with liquid only in its lower half. As a result, control of the liquid temperature by the use of a thermometer or thermostat I4 extending downward into the channel from the top of the exchanger, would be inaccurate, since the thermal device I4 would .not extend into the liquid or be sufficiently immersed to provide a true indication of the temperature.

According to the present invention, the plate 4 located beyond the seat I for the thermal device I4 (reckoned in the direction of flow through channel I2) is provided with an opening I Ia considerably smaller than the openings I I and positioned with its lower edge at a level well above the lower edges of the latter, that is, at the upper part of channel I2. The upper edge of the overflow opening I Ia is situated at the same level as the upper edges of the other openings I I. Thus, the liquid under treatment cannot flow from the left side to the right side of the apparatus, unless it rises as high as the opening Ila, whereby the liquid level will be high enough for adequate immersion of the thermal device I4. In this way, the temperature of the liquid flowing through channel I2 will be accurately measured by the thermal device I4, even though the flow rate is relatively low.

If the throughflow opening II in the other plates are circular, it may be advantageous to make the smaller opening IIa circular as well,

although it can be made oblong, that is, considerably smaller in height than in width.

I claim:

1. A plate heat exchanger comprising a plurality of vertical heat exchange plates provided at their upper portions with throughfiow openings forming a channel extending substantially horizontally along the upper portion of the exchanger, and a thermal device extending downward into the upper portion of the channel for use in controlling the temperature of a liquid flowing through the channel, the exchanger being characterized in that said opening in one of the plates, located beyond said device reckoned in the direction of the liquid flow through the channel, is smaller than said openings in the other plates and is located at the upper part of the channel with its lower edge above the level of the lower edges of the other openings and at least as- ;in which the upper edge of the opening in said one plate is at the same level as the upper edges of the other openings.

3. A plate heat exchanger according to claim in which said openings are circular.

4. A plate heat exchanger according to claim 1, in which the opening in said one plate is smaller in height than in width.

ROBERT PONTUS LARSSON HYTIE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 427,193 Schutte May 6, 1890 832,737 Kaeferle Oct. 9, 1906 1,686,614 Hume Oct. 9, 1928 1,890,108' Chatain Dec. 6, 1932 2,181,230 Groat Nov. 28, 1939 2,317,480 Peters Apr. 27, 1943 2,392,021 Wildermuth Jan. 1, 1946 FOREIGN PATENTS Number Country Date 192,912 Great Britain Feb. 15, 1923 OTHER REFERENCES Ser. No. 402,669, Nanz (A. P. C.) published May 25, 1943.

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