US1686935A - Condenser - Google Patents

Description

Oct. 9, 928. 1,686,935

. v T. SHIPLEY C ONDEN S ER 3 Sheets-Sheet 2 Filed May 51, 1924 01L TRAP.

Oct. 9, 1928.

T. SHIPLEY CONDENSER Filed May 51. 1

3 Sheets-Sheet 5 Fatented Get. 9, 1928.

UNITED STATES THOMAS SHIPLEY, or YORK, I'ENNSYLVANIA, ASSIGNOR, BY MESINEZASVSIGNYHENTS,

A 1,686,935 PATENT OFFICE.

TO YORK ICE MACHINERY CORPORATION, OF YORK, PENNSYLVANIA, A CORPORA- TION OF DELAWARE.

Application filed May 31,

This invention relates to condensers-of the so-called atmospheric type for use in refrigerating systems and particularly in those systems using anhydrous ammonia.

In twoprior applications, Ser. Nos. 691,057 and 691,058, filed Feb. 6, 1924-, which have since the filing of the present application resulted in Letters Patent Nos. 1,525,006 and 1,525,007, I describe and claim a method of and apparatus for purging refrigerating systems, in which the foreign gases are drawn 'roin the bottom of the condenser and are rappc by a liquid seal in a part or" the liquid line, such trap being located preferably between the condenser and the receiver.

In 0 era-ting according to the method just alluded to, it is necessary specially to operate or spe *ially to construct the condenser in such manner that the formation of liquid seals, either by the refrigerant or-by such lubricati no oil as-may be present, either in the bottom of the condenser or at points .1 the liquidline leading to the purging apparatus, shall be precluded.

The present invention provides a condenser which has special utility in and of itself, and which, when combined with a purging system of the type just described, ofierspeculiar practical advantages.

The purging method aud mechanism ar cla med in my applications above identified and consequently are not claimed herein, ex-.

ceptin combination with the special condenser. The scheme for returning recovered refrigerant to the liquid line or receiver disclosed in the present ap ilication is claimed in a related application Serial No. 7l,d69, filed.

October 18, 1024, and hence is not claimed herein.

(lbvious y, atmospheric condensers vary considerably in their specific form, according to the space available and the particular requirements of the plant. I have selected for illustration a simple and more or less arbitrary arrangement of the apparatus'designed to bring out the fundamental principles of the invention, and "I have purposely omitted accessory apparatus such as pumpout connections, etc, not necessary to an understanding of the invention. Accordingly, the showing in the accompanying drawings is largely limitedto the features of the present invention and is in some degree diagram matic.

CONDENSER.

1924. Serial No. 717,072.

0 In this view,- certain of the pipe coils of the condenser are merely suggested;

Fig. 3 isan elevation of a gas header casting used to connect the inlet ends of con-v denser coils;

Fig. 4: is a section on the line 44 of Fig.3; Fig. 5 is an. elevation of a. liquid header casting used-to connect-the'outlet ends of condenser coils;

Fig. 6 is a section on the line 66'0f Fig. 5. The high pressure gas line, which isconnected to the discharge of theicompressor or compressors, is shown at 6. It-discharges through a valve 7 into the body of the precooler 8. This is shown as a vertical condenser of the water tube type, in which the water tubes are shownat 9, meet the-tube sheets at 10, and the waterboxes at 11 and 12 (see Fig. 2). The water supply anddischarge connections to the respective water boxes are shown at 13 andl l.

art, atmospheric condensers are usually cooled by water flowing over them from a cooling tower (not shown) to acollectingbasin and sump (not shown), from which the water is pumped back to the cooling tower. It is conveniently possible to use the water on its way from the sump to thecooling tower for the purpose of cooling the preliminary cooler. 8, as the refrigerant gas is at a rela tively high temperature as it enters the preliminarycooler, and hence can be'effectively cooled by this water. However, the water for cooling the preliminary cooler 8 maybe drawn from any preferred source.

The action of the preliminary-cooler 8 is to cool the refrigerant partially. This results, first,,i1ithe condensation and precipitation in thecooler 8 of practically all the lubricating oil which is carried from the com pressor by the compressed refrigerant. There may be,"and commonly will be, some liquefaction of the refrigerant in the precooler8, depending, ofcourse, on the size of the interior surface of the tubes, and consequently will retard the heat transfer which takes place in the condenser.

The oil intercepted in the pro-cooler 8,

4 together with such refrigerant as is there liquefied, is withdrawn from the bottom of the pre-cooler 8 through the drain connection 15, which leads to an oil trap hereinafter described. In order to equalize the pressures of the oil trap and pro-cooler, an equalizing connection 16 is made between the top of the pro-cooler 8, and the top of the oil trap. This equalizing connection assures gravity flow of oil and liquid refrigerant from the bottom of the pre-cooler 8 through drain connection 15 to the oil trap.

The balance of the refrigerant, together with any foreign gases or vapors which may be present, is withdrawn from the body of the cooler 8 by the connections 17, two such connections being shown, each controlled by a corresponding valve 18. The connections 17 leave the pre-cooler 8 at a level above that of the drain connection 15, and each leads to a corresponding gas manifold 19. The connections 17 lead the gas to points at midlength of the manifolds 19 and these manifolds are preferably exactly level so that there will be no tendency for any liquefied refrigerant, if any be present, to accumulate in the header.

' I will now describe, with reference to Fig. 2, one of the two main condenser units, these two units being identical, as is clearly indicated in Fig. 1.

A number of branch connections lead from the manifold 19, and each is controlled by a corresponding globe valve 20. It is important that these valves be set with their stems horizontal, so that the valves will drain themselves, by gravity, of any liquid ammonia which might find its way into them, thus avoiding the formation of any liquid seals or traps at the valve seats, and insuring the equal distribution of the refrigerant to all the condenser coils. 7

Four branch connections from the manifold 19 are shown in Fig. 2, but there may be more or fewer. Each such connection is controlled by a valve 20 and each leads to a plurality of condenser coils (three being a convenient number) by means of a self-draining manifold fitting 21. This fitting is shown in detail in Figs. 3 and l, and, as shown in that figure, each fitting includes a main connection 22 and three branch connec' tions 23. The main connection receives refrigerant from the corresponding valve 20,

and the branch connections 23 are connected Each coil 24 is so formed and arranged ,that, as the refrigerant is condensed in it, it

drains freely by gravity to the bottom of the coil. Furthermore, the pipe of which the coil is made is of such size that its bore will never be filled by the liquid refrigerant flowing through it. In other words, each convolution of each-coil is more than adequate to conduct all the refrigerant which may be condensed within it and within all the convolutions above it.

' The fittings 21 are so formed that the branch connections 23 are all at a decidedly lower level than the main connection 22, and the ports are so shaped that no pockets for the accumulation of liquefied refrigerant are offered.

The three coils-24- of each group are similarly connccted at their lower ends by a manifold connection 25 (see Figs. 5 and 6) which is practically identical in form with the manifold connection 21, but inverted so as to permit free gravity flow of the liquid refrigerant from the coils 24 to a globe angle valve 26, which also stands with its stem in a horizontal position to preclude the formation of any pockets at or around its seat.

There is a fitting 25 for each group of condenser coils so that, in the example illustrated there are four such fittings 25, and four angle valves 26. The angle valves'26 are connected by vertical branches to two reversely inclined manifolds 27. These manifolds 27 are of such. size and are sufficiently steeply inclined to feed all the liquid refrigerant to the T fitting 28 without permitting any branch manifold 25, any valve 26, or any part of the manifold 27 to become completely flooded. The T fitting 28 is connected to an inclined branch 29 and these, like the parts just described, are adequate to convey all the liquid refrigerant which they receive, without floodlng.

The condenser unit just described is one of two, and consequently there are two branches 29 which are connected to the main liquid line 30. This is a vertical pipe which extends downward to an oil separating trap 31 and enters the side of said trap through an inclined opening 32. The purpose in so entering the trap is to assist the gravity separa tion of oil and liquid refrigerant in the trap 31.

This trap is provided with a gauge glass 33, and a horizontal baflle 34, below the inlet 32, andpreferably at or slightly above anormal level of oil in the trap. The liquid refrigerant passes off through the connection 35, which is above the connection 32, through a globe valve 36, to the receiver 37.

The drain connection 15 enters the through a downwardly inclined fitting 38 be low the baflle 34 and the equalizing connection valved connection 39.

The foreign gas eliminator is formed as a sort of by-pass or extra volume in communication with the main liquid line '30. A branch leaves the line 30 by way of the fitting 40 and returns by way of the fitting 41. Flow through the fitting 40 is controlled by a valve 42. This branch leads to a shell 43, known as the purge drum. Between the bottom of the purge drum 43 and the lower fitting 41, there is a pipe connection controlled by two valves, the first of which, 44, is at or near the bottom of the drum 43-, and the second of which, 45, is at or near the fitting 41. The essential thing is that there shall be an interval be tween the valves 44 and 45 affording a volume suiiicient to receive all the refrigerant which may be trapped between the valves 42 and 45 after such refrigerant has been liquefied. I

The purge drum 43 is provided with a valve controlled gauge 46 and a thermometer and well 47, and it may be chilled by an expansion coil 48 to which liquid refrigerant is admitted through the expansion valve 49 and from which the expanded refrigerant is withdrawn to the compressor through a connection 50. Purge valve 51 permits gases to be vented from the purge drum 43.

In the ordinary operation of the plant, the valves 42, 44, and 45 are open. The purge drum 43 and its pipe connections serve therefore merely as an extra volume connected with the liquid line. Foreign gases are not condensed in the condenser and being heavier than the gaseous refrigerant they flow downward through the coils 24, fittings 25, valves 26, manifolds 27, and connections 29 to the liquid line 30. They arefree so to fiow because the construction of the condenser is such that no liquid seals or traps impede the flow of the foreign gases.

The trap 31, however, is filled to the outlet 35 with liquid and consequently the foreign gases are held back and separated from the liquid refrigerant at this pointand accumulate in the'purge drum 43 and its connections.

lVhen the for ign gases have accumulated in considerable volume, the head pressure will rise materially above that corresponding to the temperature of the refrigerant leaving the condenser. lVhen this condition exists the system is purged as follows:

The valves 42 and 45 are closed, isolating the purge drum 43 from the liquid line 30. The expansion valve 49 is then opened to permit liquid refrigerant to expand into the coil 48. This'so chills the gases within the purge drum 43 that the refrigerant gas is liquefied practically completely and drains through the open valve 44 into the connection between this valve and the valve 45.

When all the refrigerant has been liquefied,

this fact will be indicated by the relation-of temperature to pressure in drum 43. 1 Then the valves 44 and'49 are'closed and the valve 45 is opened. This permits the liquid refrigerant to flow by way of the fitting41 through liquid line 30 to the trap 31 while the foreign gases are retained in drum 43. The valve 51 is then opened to vent the foreign gases to the atmosphere after which the valve 51 is closed and the valves 42 and 44 are opened.

This completes the purging operation and restores the purge drum 43 to communication with the liquid line 30.

The purging mechanism and method just described are essentially the same as those described and claimed in my prior applications, except for the arrangement ofthe valves 44 and 45, by which the liquefied refrigerant recovered from the purge drum is delivered to the liquid line instead of being fed to the low pressure gas line, i. e., tov the suction of the compressor.

v The arrangement shown in the present application is simpler and somewhat more economical. i

The condenser above described is simple in construction and has proved to be highly efficient in operation. The preliminary cooler effects a quite thorough removal of oil and maintains the efficiency of the main condenser units by preventing them from becoming coated with oil. I

The-construction of the main condenser units and their connections is such that liquefied refrigerant is quickly led away so that practically the entire surface of the condenser is effective for condensing purposes. Furthermore, because of the free flow of liquid from the condenser and the avoidance of all liquid seals, the foreign gases are not trapped in the condenser and hence do not reduceits efiiciency, but gradually accumulate in a volume provided therefor in a part of the system where they do not retard the useful transfer of heat.

Connections bGtWGGILtl1GPY-COOlGT and the oil trap are such as to be favorable to active separation of the oil and liquid refrigerant. The entire plant is one which tends to operate at high efficiency and which may be maintained in this condition by occasional purging of the drum 43 practically Without the loss of refrigerant.

. WVhile the general principles involved in the design of the condenser can doubtless be understood by those skilled in the art, from the above description, I wish to point out one ortwo important factorsto insure a full appreciation of their importance, and to insure a clear understanding 01 certain terms successive convolutions, favorable togravity in 111)1" 1 l 0 b lifi f .i ow or corn erisec ieiii eran 0 1e owcni o the coil. ln coilsof the usual construction successive convolutions are parallel and where this construction is used, the exact leveling of the coils is a matter of importance. Furthermore, the total length of the coil, and the diaineterof the piping used, must be so correlated that the liquid flow capacity at all points in the coil is more than suflicient to discharge under the available gravity head more condensed refrigerant than that coil and all the coils above it can supply. In other words, the liquid flow rate must be so great, relatively to the rate of condensation, that a gas passage is maintained throughout the length of the coil continuously or substantially so. Otherwise, heavy foreign gases, which are non-eondensible, will be trapped in the con denser.

Another important point in the design is the construction of the liquid oiftalres in. such manner that their liquid flow cap acity is more than suiticient to discharge all the liquid refrigerant delivered by the condensing coils which discharge into them. This result is secured partly by using unusually large oii'talre fittings and partly by increasing the flow gradient through the oiftake fittings and the headers progressively, so that as the various streams of condensate oin, their speed of flow will be increased. By incl-easingthe speed of flow in the manner described, it is possible to use fittings of smaller size than would otherwise be practicable and still maintain within the fitting a free passage for the foreign gases.

What is claimed is:

1. A condenser for refrigerating systems, comprising in combination, a plu ality of pipe coils arranged to drain themselves of liquid refrigerant by gravity flow; a manifold offtake for the condensed liquid arranged for gravity flow, and having at all points a gravity liquid flow capacity in excess of the condensing capacity of the coils discharging thereinto, whereby a gravity flow outlet for heavy gases is afforded by said otltake; a chamber in communication with said ofitake; a liquid seal beyond said cham ber arranged to intercept gases and pass liquid refrigerant; means serving to segregate the non-condensible portion of said intercepted gases within said chamber; and means for venting said chamber.

2. A condenser for refrigerating systems comprising in combination, a plurality of pipe coils arranged to drain themselves of liquid refrigerant by free gravity flow; a

manifold oiitake for the condensed liquid arranged for free gravity flow and having'at all points a gravity liquid flow capacity in excess of the condensing capacity of the coils discharging thereinto, whereby a gravity flow outlet for heavy non-condensible gases is afforded through said oil'take; and means for arresting and accumulating outside the condenser the off-flowing non-condensible gases while permitting the flow of condensed refrigerant. v

8. A condenser for gaseous refrigerants comprisingin combination a plurality of coils so constructed and arranged that the rate of liquid flow is so great relatively to the rate of condensation, that a gas passage is maintained throughout the length of the coil; a manifold oiftake for said coils having a gravity liquid flow capacity greater than the condensing capacity of said coils; means for intercepting uncondensed gases discharging through said ofl'talre; and means for isolating and discharging the noncondensible portions of said intercepted gases.

4-. A condenser for gaseous refrigerants comprising in combination a plurality of coils so constructed and arranged that the rate of gravity liquid flow is so greatrelatively. to the rate of condensation, that a gas passage is maintained throughout the length of the coil; a manifold oiftake for said coils havinga gravity liquid flow capacity greater than the condensing capacity of said coils, and including multiple-branched units having a steep flow gradient and devoid of liquid retaining pockets; means for intercepting uncondensed gases discharging through said oiftake; and means for isolating and discharging the non-condensible parts of said intercepted gases.

5. In a refrigerating plant, the combinati'on of a pre-cooler connected to receive refrigerant to be condensed; a condenser connected to receive gaseous refrigerant from the pro-cooler; an oil removing trap; a receiver; and connections for conducting condensed liquids from the pre-cooler and condenser to said receiver through said trap.

6. In a refrigerating plant, the combination of a pro-cooler connected to receive refrigerant to be condensed; a condenser connected to receive gaseous refrigerant from the pre-cooler; a receiver connected to receive liquefied refrigerant from the condenser; an oil removing trap interposed in' the lastnamed connection and provided with a battle below the liquid level therein; and connections arranged to drain condensed liquids from the pro-cooler and discharge them into said trap below said baffle.

7. A condenser for refrigerating systems comprising in combination, a pre-cooler arranged partially to cool refrigerant, and thereby liquefy entrained oil and condense a part of the refrigerant; a main condenser lill) arranged to receive from the pre-cooler the uncondensed portion of the refrigerant tgether with such non-condensible gases as may be present, said condenser including a plurality of coils arranged for free gravity flow of liquid refrigerant and a gravity discharge of sufficient capacity to discharge all condensed refrigerant and simultaneously maintain a constant gravity outflow passage for heavy non-condensible gases; a liquid lineleading from said condenser and including a trap arranged to pass liquid refrigerant and arrest oil and gases; and a drain connection for leading condensed liquids from said pre-cooler to said liquid line.

8. A condenser for refrigerating systems comprising in combination, a pr -cooler arranged partially to cool refrigerant; and thereby liquefy entrained oil and condense a part of the refrigerant; a main condenser arranged to receive from the pre-cooler the uncondensed portion of the refrigerant'together With such non-condensible gasesas may be present, said condenser including a plurality of coils arranged for free gravity flow of liquid refrigerant and gravity discharge connections of sufficient capacity to discharge all condensed refrigerant and simultaneously maintain a constant gravity outflow passage for heavy non-condensible gases; a liquid line leading from said'condenser including a trap arranged to pass liquid refrigerant and arrest oil and gases;

a drain connection for leading condensed liquids from said pre-cooler to said liquid line; and a purge drum associated With said liquid line and arranged to accumulate 'non condensible gases discharged thereinto by said condenser.

9. In a condensing plantfor treating the less of said refrigerant; a drain connection for conducting such l1qu1d from said precooler; a gas connection leading from said pre-coolcr at a level above said drain connection; a main condenser connected to be fed by said gas connection and arranged to dis charge liquefied refrigerant together with non-condensible gases; a trap arranged to prevent the passage of oil and of non-condensible gases, connected to receive liquid from said drain connection and also the discharge from said condenser; a receiver fed with liquid refrigerant by said trap; and

cooler; a. gas connection leading from said pre-cooler at a level above said drain connection; a main condenser connected to be fed by said connection and arranged to discharge liqueiied refrigeranttogether With non-condensible gases; a trap arranged to prevent the passage of oil and of non-condensible gases, connected to receive liquid from said drain connectionand also the discharge from said condenser; a receiver fed with liquid refrigerant by said trap; and means for. isolating and discharging non-condensible gases, interposed in thevconnection between said condenser and said trap, said means including a cooling coil for liquefying such refri erant as may be present and a gravity drain connection operable to drain such liquefied refrigerant to said trap.

In testimony whereof I have signed my name to this specification;

THOMAS SHIPLEY.

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