US2344606A - Double pipe expansion chiller - Google Patents

Description

March 21, 1944. EDMQNDS DOUBLE PIPE EXPANSION CHILLER Filed Aug. 50, 1943 2 Sheets-Sheet l March 21, 1944. E. A. EDMONDS DOUBLE PIPE EXPANSION CHILLER Filed Aug. 50, 1943 2 Sheets-Sheet 2 Patented Mar. 21, 1944 2,34%,606 DOUBLE PIPE axriipsrox CHILLER l Eugene A. Edmonds, Louisville, Ky., assignor to Henry Vogt Machine Co., I c., Louisville, Ky., a corporation of Kentucky Application August so, 1943, Serial No. 500,573

Claims.

This invention relates to double pipe chillers.

of the type comprising a stack of superposed pairs of laterally parallel, substantially horizontal inner pipe sections, serially connected to provide for the serial flow of a liquid to be cooled through all the inner pipe sections of said stack, each inner pipe section being surrounded by a jacket spaced therefrom to form the evaporator element for a liquid refrigerant, in heat exchanging relation to the surrounded inner pipe sections, the jackets of each laterally parallel pair of pipe sections being connected in cascade relation whereby liquid refrigerant admitted to the top pair of jackets successively flows into the next lower pair of jackets, and so on, each pair of Jackets being provided with an equalizing connection opening into the bottom of each, and dipping intermediately below said bottom level whereby to collect the lubricating oil which con-1 taminates the refrigerant. Vertically adjacent pairs of jackets are in intercommunication by an overflow connection opening into the above pair at a point which determines the level of liquid refrigerant therein, and opening into the lower pair at a point below the liquid level.

In known chillers of this type, the overflow connections are common to each pair of jackets, so that the liquid refrigerant flows serially through all of the evaporator chambers. In the most improved known chiller of this type, which is exemplified in the disclosure of application for patent Kubaugh, Ser. No. 464,230, filed November 2, 1942, there is an equalizing connection between the jackets of a pair at each end, an overflow connection at each end, and a gas collecting conduit at the middle of each jacket above the liquid level therein, so that the path of distribution of the liquid refrigerant in each evaporator chamber and the path of withdrawal of the gaseous refrigerant are minimized, maintaining the body of liquid refrigerant in each chamber substantially level under conditions of ebullition.

In the known type of chiller, as above described, the equalizing connections have the dual function of an oil sump and an equalizer, and are provided with valved discharges from which the accumulated oil may from time to time be drained. During the interval between draining, the body of oil which may have collected is churned and dissipated by the flow of liquid refrigerant through the equalizing connections in the performance of their function as equalizers. This is a drawback, as it prevents complete elimination of oil from the refrigerant and impairs the heat exchanging efllciency of the apparatus.

One of the objects of the present invention is to employ transverse connections which are positionally and structurally analogous to the equalizing connections in the above described known type of chiller, but to divorce them from any equalizing function so that they act solely as oil sumps in which the oil collects under quiescent conditions so that it remains in the sumps until such times at which the sumps are drained, permanently segregated from the body of liquid refrigerant within the jackets.-

The equalizing function is necessarily relegated to another set of transverse connections between the jackets of each laterally parallel pair, which connections are preferably above the bottoms of the jackets so as to avoid the accumulation of any oil in said connections.

Another object of the invention is to provide, for each group of vertically adjacent pairs of laterally parallel jackets, a combined equalizing and overflow conduit arrangement, connected in parallel to the jackets of each pair, whereby the jackets of each pair fill simultaneously to the common overflow level, and then discharge simultaneously by way of said overflow into the equalizer of the next pair below, thus reducing by onehalf, the distance of travel of liquid refrigerant throughout the jackets of the stack as contrasted with known chillers of this general type in which the liquid to be cooled flows seriatum through all the jackets.

Since the liquid to be cooled flows serially through the inner pipe sections, it will be of different temperature in the respective pipe sections of each laterally parallel pair, producing a different rate of ebullition and gaseous refrigerant evolution in the respective laterally related jackets.

An object of the present invention, therefore, is to provide a transverse overflow connection between the jackets of a pair, connecting them in parallel, extending to the tops of said jackets and being of large enough diameter to act as a capacious gaseous refrigerant equalizer as'well as an overflow pipe. Since a pipe of such size will ordinarily extend below the desired liquid level in the laterally adjacent jackets, the invention con-.

templates the provision of dams, obstructing the lower parts of the transverse overflow connections up to a height which determines the desired liquid level in the connected jackets.

Other objects of the invention will appear as the following description of a preferred and practical embodiment thereof proceeds.

In the drawings which accompany and form a illustrating the parallel overflow and equalizing conduit pipe unit;

Figure 4 is a fragmentary view in vertical section showing details of the dam construction in the transverse common overflow connection.

The drawings show in detail a double pipe chiller comprising a stack of substantially horizontal inner pipe sections l, arranged in two banks and the corresponding inner pipe sections of each being laterally parallel in the same horizontal plane. The inner pipe sections are, connected at one and the same end by the vertical return bends 2 and at the opposite ends by the horizontal return bends 3, whereby all of the inner pipe sections are serially connected. One of the pipe sections of the lowermost pair is provided with the liquid inlet 4 and one of the pipe sections of the uppermost pair is provided with a liquid outlet 5. The liquid to be cooled thus enters at one end of one of the bottom pipe sections and circulates serially through all of the pipe sections of the chiller before it is discharged by way of the liquid outlet 5..

The inner pipe sections 1 are each surrounded by a jacket 8, the space between said jackets and pipe sections constituting an evaporator chamber for containing liquid refrigerant up to a certain level.

Liquid refrigerant is fed to the jackets of the uppermost pair by way of the branched conduit 1, communicating at 25 with a source of liquid refrigerant, and the jackets of all the pairs are arranged in cascade relation sothat the liquid refrigerant after filling the uppermost pair of jackets to a determined level flows concurrently into both jackets of the next below pair until they are filled up to a certain level whereby they in turn discharge simultaneously into the pair of next below jackets, and so on until all of the jackets are thus filled to a predetermined level. The depth of liquid refrigerant in the lowermost pair of jackets is controlled by float valve mechanism, in general designated by the reference character 8, in which the same liquid level is maintained as in the lowermost pair of jackets 8 by the intercommunicating conduit 25, and which upon the lowering of the liquid level in the lowermost pair of jackets, opens to admit liquid refrigerant by way of the conduit 1 into the uppermost pair of jackets, and thus maintain the required liquid level in all the jackets.

Suction conduits 9 are provided individual to each jacket or pair of jackets, in communication with the jackets at a point intermediate their ends and above the liquid level in said jackets, said suction conduits being connected into a common suction pipe I 0, which leads to a gaseous refrigerant accumulator ll, connected to the suction side of the compressor of the refrigerator system by the conduit 21. The accumulator ll acts as a separator, returning any liquid refrigerant which may have been drawn into the accumulator with the gas. to the top pair of jackets, preferably, by means of a pipe l2 bent, as shown at ii, to form a liquid seal.

Commonly, chillers of this type are provided with driven scrapers, not shown, which scrape the inner surface of the pipe sections l free from deposited matter, and thus maintain the heat exchanging efliciency of the chiller. Figure 1 shows the shafts i3 by which said scrapers are driven, and the chain and sprocket connections in general designated by the reference character I4 and operated by the motor l5, which operate the scrapers.

It is, of course, known that a certain amount of the oil which is employed to lubricate the moving parts of the compressor leaks into the body of the liquid refrigerant and is carried with the refrlgerant into the chiller. The presence of such oil is objectionable, in that it forms a grease film on the outer surfaces of the pipe sections i, and to that extent reduces the heat conductivity of the walls of said pipe sections. The subject invention provides for'the continual separation of the oil from the liquid refrigerant and the permanent segregation of the oil from the liquid refrigerant body. This provision comprises the transverse pipe connections l8 individual to each pair of laterally adjacent jackets, communicating with said jackets at their bottom level and intermediately dipping below said bottom level. Said connections are preferably unbroken, arcuate pipe sections suitably secured as by welding, to the respective jackets. The pipe sections I6 serve as oil sumps for collecting the lubricating oil which contaminates the refrigerant, and are preferably installed at the lower ends of the laterally adjacent jackets and provided with valved discharges I! so that the sumps can be periodically drained of lubricating oil. As shown in Figure 2, the valved connections I! preferably discharge into a single drain manifold 18, from the lower end of which the lubricating oil can be recovered.

In the absence of provisions to the contrary, the sumps I 6 would act also as equalizers for the body of liquid refrigerant in the adjacent jackets of a pair, as is commonly the case in known chillers of this general type. There is always a flow of liquid refrigerant through such equalizers in one direction or the other, for the liquid level in adjacent jackets seldom remains equal, due to different rates of ebullition in the respective lateral jackets incident to the fact that the liquid to be cooled passes serially through the inner pipe sections and is cooler when it enters one of the lateral pipe sections of a pair than when it enters the other. In the older form of chiller where the sump also functions as a liquid refrigerant equalizer, the fiow of liquid refrigerant churns the oil and carries a part of it out into one or the other, of the laterally related jackets so that it is impossible to completely free the refrigerant from the contaminating oil. By the present invention the pipe connections I6 are divorced from any function as equalizers through the provision of other transverse connections is between laterally adjacent jackets, located above the bottom level of said jackets so that they are not in a position to collect oil, and which communicate with the respective jackets below the normal liquid level in said jackets. Thus, the oil which accumulates gravitationally within the sumps l5 remains quiescent and undisturbed, completely segregated from the bodies of liquid refrigerant in the respective Jackets.

The subject invention also comprehends the supplying of liquid refrigerant in parallel, in successively descending order, to both banks of jackets.

This is accomplished, as best shown in Figure 3, by the provision of a transverse overflow pipe connection 20, for each pair of horizontally juxtaposed jackets communicating at its opposite ends with the respective jackets at points which determine the liquid level therein. This pipe is preferably located above the liquid refrigerant equalizer IQ of the next lower pair of horizontally related jackets, and connected thereto by the pipe 2| which, to facilitate assemblage, is made in sections with a flanged couplng, as shown. It is obvious that liquid refrigerant overflows from both jackets 6 of the upper horizontal pair through the common pipe 2!, and flows into both jackets of the lower horizontal pair through the equalizer IS.

The overflow and equalizing connections between alternate vertically adjacent pairs of jackets are of necessity longitudinally staggered, as indicated at 22 and 23 in Figure 1. This figure also shows that the overflow and equalizing connections are preferably duplicated at opposite ends of the jackets, gaining the advantag present in the invention of the hereinbefore mentioned Kubaugh application of minimizing the length of travel of the liquid refrigerant longitudinally through the jackets. Q

Reference has been made to the fact that the rate of ebullition in horizontally adjacent jackets is generally unequal, creating differential gas pressures in the respective'jackets, which has a tendency to depress the liquid level in one jacket below that in the other. The present invention overcomes this tendency by causing the pipe connection 20 to function as a gaseous refrigerant equalizer'for the two jackets which it interconnects. This is done by having the pipe 20 communicate with the adjacent jackets at the level of the top of said jackets, and by making the pipe 20 of sufficiently large diameter to provide a capacious gas passage above the overflow level of the liquid refrigerant. Since the area of communication of such a large pipe with the respective jackets will extend below the desired liquid level, dams 24 are provided in said pipe, obstructing the lower portion of the bore thereof up to a height which determines the liquid level in the respective jackets.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of the invention, it will be understood to those skilled in the art that the specific details of construction and arrangement of parts are by way of example and not to be construed as limiting the scope of the invention defined in the appended claims.

What I claim as my invention is:

1. Double pipe chiller comprising a serpentine coil having the form of side by side banks of superposed jacketed straight substantially horizontal inner pipe sections serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between longitudinally adjacent jackets communicating therewith above the bottoms of said jackets and below the normal liquid level therein, sump connections between said horizontally adjacent jackets communicating therewith at the bottom level of said jackets and dipping intermediately below said level, said sump connections being provided with valved drainage outlets, and an overflow connection between each horizontally adjacent pair of jackets and the next lower pair, communicating with the upper pair at a point determining the liquid level in said pair and with the lower pair at a point below the liquid level in said lower pair.

2. Double pipe chiller comprising a serpentine coil having the form of side by side banks of superposed jacketed straight substantially horizontal'- inner pipe sections serially connected at opposite, ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between longitudinally adjacent jackets communicating therewith above the bottoms of said jackets and below the normal liquid level therein, sump connections between said horizontally adjacent jackets communicating therewith at the bottom level of said jackets and dipping intermediately below said level, said sump connections being provided with valved drainage outlets, and an overflow connection between each horizontally adjacent pair of jackets and the next lower pair, communicating with the upper pair at a point determining the liquid level in said pair, and with the equalizing connections between the jackets of said lower pair.

3. Double pipe chiller comprising a serpentine coil having the form of side by side banks, of superposed jacketed straight substantially horizontal inner pipe sections serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between horizontally adjacent jackets, adjacent each end, communicating therewith above the bottoms of said jackets and below the normal liquid level therein, sump connections between longitudinally adjacent jackets, adjacent one end, communicating therewith at the bottom level of said jackets and dipping intermediately below said level, said sump connections being provided with valved drainage outlets, and an overflow connection between each horizontally adjacent pair of jackets and the next lower pair, communicating with the upper pair at a point determining the liquid level in said pair, and with the lower pair at a point below the liquid level in said lower pair.

4. Double pipe chiller comprising a serpentine coil having the form of side by side banks of superposed jacketed straight substantially horizontal inner pipe sections serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between horizontally adjacent jackets, adjacent each end, communicating therewith above the bottoms of said jackets and below the normal liquid level therein, sump connections between longitudinally adjacent jackets, adjacent one end, communicating therewith at the bottom level of said jackets and dipping intermediately below said level, said sump connections being provided with valved drainage outlets, an overflow connection between each horizontally adjacent pair of jackets having the next lower pair, communicating with the upper pair at points determining the liquid level in said pair, and with the respective equalizing connections between said lower pair.

5. Double pipe chiller comprising a serpentine coil having the form of side by side banks of superposed jacketed straight substantially horizontal inner pipe sections serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between longitudinally adjacent jackets communicating therewith above the bottoms of said jackets and below the normal liquid level therein, sump connections between said horizontally adjacent jackets communicating therewith at the bottom level of said jackets and dipping intermediately below saidlevel, said sump connections being provided with valved drainage outlets, and an overflow connection between each horizontally adjacent pair of jackets and the next lower pair, comprising a conduit communicating at one end with the equalizing connection between the lower pair and at the other end with a pipe connection communicating with the respective jackets of the upper pair at points determining the liquid level within said jackets.

6. Double pipe chiller comprising a serpentine coil having the form of sideby side banks of superposed jacketed straight substantially horizontal inner pipe sections, serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between horizontally adjacent jackets communicating therewith below the liquid level therein, and an overflow connection between each horizontally adjacent pair of jackets and the next lower pair communicating at its lower end with the equalizing connection of the lower pair and at its upper end with the respective jackets of said upper pair at points determining the liquid level in said jackets.

7. Double pipe chiller comprising a serpentine coil having the form of side by side banks of superposed jacketed straight substantially horizontal inner pipe sections, serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between horizontally adjacent jackets at each end, communicating therewith below the liquid level therein, and ove; fiow connections at each end, between each horizontally adjacent pair of jackets and the next.

lower pair communicating at their lower ends with the respective equalizing connections of the lower pair, and at their upper ends with the respective jackets of said upper pair at points determining the liquid level in said jackets.

8. Double pipe chiller comprising a. serpentine coil having the form of sideby side jackets of superposed jacketed straight substantially horizontal inner pipe sections, serially connected at opposite ends providing a conduit for the flow of liquid to .be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between horizontally adjacent jackets communicating therewith above the bottoms of said jackets and below the rarmal liquid level therein, and an overflow Cull" nection between each horizontally adjacent pair of jackets and the next lower pair, communicating at its lower end with the equalizing connection of the lower pair and at its upper end with the respective jackets of said upper pair at points determining the liquid level in said jackets.

9. Double pipe chiller comprising a serpentine coil having the form of side by side banks of superposed jacketed straight substantially horizontal inner pipe sections, serially connected at opposite ends providing a conduit for the fiow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between horizontally adjacent jackets at each end, communicating therewith above the bottoms of said jackets and below the liquid level therein, and overflow connections at each end, between each horizontally adjacent pair of jackets and the next lower pair communicating at their lower ends with the respective equalizing connections of the lower pair, and at their upper ends with the respective jackets of said upper pair at points determining the liquid level in said jackets.

10. Double pipe chiller comprising a serpentine coil having the form of side by side jackets of superposed jacketed straight substantially horizontal inner pipe sections, serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, an equalizing connection between horizontally adjacent jackets, communicating therewith above the bottom of said jackets and below the normal liquid level therein, an overflow connection between each horizontally adjacent pair of jackets and the nextlower pair comprising a conduit communicating at one end with the equalizing connection between the lower pair and at the other end with a pipe connection communicating with the respective jackets of the upper pair, the areas of communication with said respective jackets extending to the tops of said jackets, said pipe connections acting as a gaseous refrigerant equalizer between the jackets which it connects and having dams obstructing the lower portion of the bore of said pipe to a height determining the liquid level within said jackets.

EUGENE A. EDMOND'S.

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