US2223882A - Refrigeration - Google Patents

Description

W. E. BELINE REFRIGERATION Den. 3, 1940.

Filed May 10, 1939 2 Sheets-Sheet 1 EVA/DORA TOR,

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IHEPMAL VALVE PE'- CEGLA TIJVG PUMP attorneys Dec., 3, 1940.

W. E. BELINE REFRIGERA'r10N Filed May l0, 1939 2 Sheets-Sheet 2 34%@ [19h 2310 IH 16C 115e llc 012. svn/Lz, l

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UNITED STATE-.sV

PATENT orricsf Y azzassz asrmoaaarion walter E. nenne, York, Pa., signor to York Ice Machinery Corporation, York,- Pa., a corporationoi Delaware Application may 1o, 1939, serial No. 212,89

12 Claims# tends to accumulate in the evaporator as a re sult'of the evaporation of the refrigerant from the mixture of oil and refrigerant.

w Such accumulation is objectionable, for several reasons. It causes foaming in the evaporator with consequent wet compression. With certain refrigerants ("Freon for. example) it raises the boiling point with consequent adverse 2o' effect on the heat exchange. Accumulatingof oil in theA evaporator is attended by depletion ofv the oil charge normally in the compressor.

Lubricating oils are miscible or soluble in some degree in practically all known refrigerants. f.

This is true even as to ammonia unless the oil ammonia mixture be substantially quiescent.`

The problem of separation is peculiarly dimcult, however, in connection with certain Are-ev frigerants now in extensive use, notably that sold under the trade name of Freon, because of miscibility of oil in all proportions in such refrigerant. Temperature, pressure andl viscosityof the oil are modifying factors in the characteristics of the mixture, but the problem of separation is substantial.

Continuous distilling processes have been proposed in which theheat for operating the still is derived from warm liquid leaving the condenser. However, such schemes are notprac- -ticable because whenever the condenser `water temperature is low, the temperature of the liquid refrigerant leaving the condenser is too lovv for an effective -distilling operation. None so' far proposed is believed tobe operative'under practical service conditions, for this and vother reasons.

Batch distilling schemes, in whichV the heatv for distilling is derived fron hot gas-'owing from the compressor to the condenser hvebeen proposed and are workable in certain cases, but are not satisfactory with many refrigerants. notably Freon, for the reason that although the oil is misclble with orsoluble in the refrigerant, the oil and refrigerant have a tendency to separate under certain conditions when the lmixyline of the compressor.

(CLBZ-IIS) Iture is warmed. Infsuch case the refrigerant" settles to thebottom and vthe oil floats on top. Y

`As a result of this effect, the batch still occasionally functions to return to the compressor f a considerable quantity of refrigerant in the liquid phase. This causes foaming in the crank case and is highly objectionable since it impairs lubrication. Hence such systems are impracticable for direct and automatic return of oil to the crank case. Y

The presentV invention offers a continuous and automatic distilling equipment, in which the `heat for distilling is preferablyA derived from hot compressor discharge gas. However the heat is provided, the still includes a separating 1.5

chamber with one connection for returning oil directly to the crank case of the compressor4 and another connection for 'returning refrigerant in the vapor phase directly to the suction The still draws oil-re- 20 frigerant mixture'from the evaporatorat a rate so limited that all refrigerant is evaporated.l A superheat responsive, flow controlling valve simi-- lar to an automatic expansion valve is the best means known to ensure such a ilow rate. Means 2'5 can be interposed between the separating cham# ber' and the crank case to returnthe oil .to the crank case when the compressoris remote from or above. the level of the still or b oth.- y

A system of the type in which hot compressor 30 discharge gas is used for heating, penalizes the overall efficiency of the refrigerating circuit in a slight degree, but the penalty does not exceed 1% so that the markedly better separation secured justifies the use of the system. 35

A number of different embodiments will be disclosed indicating the versatility of the in- 4ventive concept. For example, it can be used. with a spray type. evaporator in which the refrigerant is circulated lby a pump and showered 40 -over the heatv transfer surfaces. .It-can be arranged toreturn the oil to the compressor over a wall or even 4when the compressor is located at fan" elevation higher than that of the still.

l It can be arranged to work when the still must 45 be located atan elevation higher than the condenser or higher than both the 'evaporator and the condenser." It can also be arranged to operate with' flooded evaporators not having a circulatingpump.

' While it is impossible to illustrate all the possible variants that can be worked out, the various embodiments hereinafter described will illustrate the principles involved. and will readily suggest to those skilled in the art, the con- 55 trolling factors as to each phase of the problem.

Basically, however, the invention involves a continuous distilling apparatus arranged to derive heat from hot gas leaving the compressor, and in which the parts are so coordinated with the refrigeration circuit that refrigerant is substantially completely removed from the oil and returned to the compressor suction line and the l0 oil thus freed of refrigerant is automatically and substantially continuously returned to the compressor crank case.

This is a definite advance over batch methods, all of which, so far as applicant is aware, involve either manual periodic controls or cyclic controls incident to the starting and stopping of the compressor. Unlike batch systems a system according to the present invention becomes operative to return oil, and only oil, to the crank case as soon as the compressor starts into operation. The system remains continuously in operation while the compressor runs. Hence the system is effective without regard to load, shut-downs or other factors which affect, if they do not control,

the functioning of prior systems.

In the drawings:

Figure 1 is a diagrammatic view of a refrigerating circuit embodying my invention and showing an evaporator of the type in which the refrigerant is recirculated by a pump, the still being shown below the evaporator and above the condenser, and the oil return being provided with a trap which is needed only in cases where the oil must be returned over a wall or to the crank case of a compressor located at a higher elevation.

Figure 2 is a sectional detail view of the trap used in Figure 1.

Figure 3 shows a modified arrangement in which the oil still is above both the evaporator and the condenser. Since the still is located at a level higher than the crank case of the compressor no trap is required.

Figure 4 shows a further modification in which the oil still is located approximately as in Figure 1 with reference to the evaporator and the condenser, but being above the compressor crank case, no oil trap is required. In this view the use of a manually adjustable now control valve on the still circuit is indicated.

Figure 5 is a view of a further modification, showing the use of a different type of evaporator not requiring the use of a circulating pump. The location of the still is similar to that in Figure 4.

embodiment 0f Figures 1 am 2 The compressor is indicated at 6 and has a crank case 'I designed to serve as an oil sump. The suction line 8 leads to the side of the cylinder, and according to the construction commonly used, the piston is of the trunk type with inlet valves carried in the piston.

In some compressors of this type, the suction space below the head of the piston is in free open communication with the crank case. In other types they are isolated to the extent that the piston has a closed skirt and an oil scraping ring on such skirt somewhat restricts communication. Even in the latter case the crank case pressure l approximates suction pressure in the system at all times. Consequently, with reference to Figure 1 and all other embodiments in the present case, it may be assumed that the crank case is at or substantially at suction pressure.

The discharge line 9 from the compressor enters chamber I0 in the shell I I of the oil still to the left of a partition indicated at I2. The line I3 leaves the chamber I0 and is in free communication with the condenser I4 which may here be assumed to be of the water cooled type, 5 although the specific type of condenser is not controlling. The invention has particular importance where a water cooled condenser is used, for the reason above explained.

Extending through the chamber I0 is a heat 10 exchange coil I5 here `indicated as a simple zigzag coil without fins, but persons skilled in the art will understand that this showing is diagrammatic and that the coil may assume any form necessary or desirable to give an adequate heat l5 exchange surface between the hot gas flowing from '9 to I3 through chamber I0 and a mixture of refrigerant and oil owing from left to right through the coil I5. The coil I5 discharges into the oil separation chamber I6 within shell II to 20 the right of partition I2.

Before going further into the details of the still circuit, the remainder of the main refrigeration circuit will be traced.

From the bottom of the condenser I4, liquid 25 passes through a high side float valve I'l and thence through a liquid line Y I8 to the evaporator I9. The heat exchange surface in the evaporator may take any form and no attempt to illustrate it is madef A recirculating pump 2| draws liquid 30 refrigerant from the bottom of the evaporator I9 and delivers it through a connection 22to the spray pipe 23 within the evaporator I9.

It will readily be understood by those skilled in the art that the liquid refrigerant discharged 35 through the spray pipe 23 will flow over heat transfer surfaces such as tubes located in the evaporator but not shown, and will evaporate under suction pressure in the system because the top of the evaporator is connected by the suction 40 line 24 with the intake 8 of the compressor 6. The latent heat of vaporization is derived from the heat transfer'surfaces.

It is obvious thatv with a refrigerating circuit such as that above described, oil leaving the com- 45 pressor through the line 9 and entrained by hot gas will pass through the shell II and connection I5 to the condenser. The refrigerant will be liqueed in the condenser and will there mix with or dissolve the oil, so that an intimate mixture of 50 refrigerant with a, small percentage of oil will pass to the evaporator I9.

In the evaporator only the refrigerant evaporates, and substantially all the oil remains, thus creating an inherent tendency for the oil concen- 55 tration in the evaporator to rise steadily as the system operates. To hold this concentration within reasonable limits and to maintain an adequate quantity of oil.' in the crank case l, a portion of the refrigerant-delivered by the pump 2| 60 through the connection l22 is diverted to a branch line 25 and thence fed through the ow control valve 26 to the coil I5 in the oil still.

While any type of flow control valve may be used, Iprefer to use a flow control valve of the 65 thermal control type, in which the pressure in the thermostatic bulb 21 communicated to a diaphragm in valve 2 6 by way of the tube 28 acts in a valve opening direction and opposes pressure on the discharge side of the valve 26 acting 70 in a valve closing direction. 'Ihe control is such that refrigerant leaving the chamber I6 and passing to the suction connection 8 by way of the branch suction line 29 is always slightly superheated. 'Ihis amounts to saying that the valve Z5 26 automatically regulates the flow through coil I to a rate such that all the refrigerant passing valve-26 will be evaporated. It must be completelyevaporated if slight superheating of the vapor occurs. Such valves valves of known commercial forms and are well known; Any preferredV form capable of ensur-l ingcomplete evaporation may be used. Thus the coill l5 discharges vaporized refrigerant andl also `oil 4which is substantially free of refrigerant into illustrated, 'if the bottom of the still iI'were-above the crank case-'L'but Figure 1 the o il level in is designed to show the solution of a more dliiicult problem in which the location of the compressor i is relatively high and remote and communication must be made over a wall or partition 3l. -Such conditions are encountered in commercial installations.

Thus in Figure i the oil discharge connection' 32 which leaves from the chamber i6 cannot lead directly to the crank'case l. Instead it leads v through a check valve 33 to a iloat trap 34. From the bottom of this oat trap the return line 36 leads to crank case 'i through a strainer 3l and a check valve 3%. A

The construction of the trap is shown on an enlarged scale in Figure 2. A connection 39 leads from the top of condenser i4 and is consequently subject to the discharge pressure ofthe coinpressor (that is, subject to high side pressure). This connection leads tothe top of the trap 34. Another connection 4i leads from the top of the trap- 34 to the branch-suction line 29. The purpose of these two connections is to subject the interior of the trap 34 alternatively to high side and to low side pressures.

A float 42 inthe trap is guided for vertical movement by a stem 43. A toggle mechanism, comprising two toggle levers d4 hinged together and sustained at theirV remote ends by the leaf springs t5 which tend to approach each other andare forced outward by the toggle levers 44, forms a quick throw mechanism by means of which the oat 42 closes the valves dit and 4l selectively. 4

The normal condition is with the float down, at which time the valve it seats downward and prevents the entrance of high side pressure through the connection 39. At such time the valve 4l] is open and the interior of the trap 34 is at suction pressure. Thusoil may enter freely through the pipe 32 and check valve 33. l

When the oil accumulates toa sufiicient depth, it will cause the float 42 to rise. When the toggle shifts it will open the valve 46 and close the valve till. This cuts off the connection to the low side of the system by way of line 29 and subjects the interior of thetrap to high side pressure. It follows that the oilin the trap is displaced by .flow through the pipe13i and enters the crank case l which is at low side pressure. Consequent descent of the float 42 causes the toggle to shift and thus close valve 46 and reopen valve il before the entire charge of oil leaves the trap. Thus the high side and the low side are never freely connected withl each other, but the presare' similar to expansion The liquid line sure differential is availed of to transfer the oil to the crank case.

'I'his is simply -a commercial trap chosen for,

illustrative purposes.y Equivalent devices (not all of which are traps) are-known and maybe substituted. v Embodiment of Figure 3 The construction shown in Figure is essential-l l ly similar to that shown in Figure 1, n l parts are numbered similarly with'a distinguishing letter a. 'Ihe differences can readily be explained.

The still here shown is located above the evap- -orator and above the compressor. Its indicated position above the `condenser is not essential. In

and similar v give proper flow to the compressor crank case.

The float valve 4i ensures that the refrigerant is in the liquid phase before it leaves the still. ia from thev condenser meets the line 4 2 and they both enter the end of the spray pipe l23a remote from the pump 2id. This is illustrated as a possible alternative way of supplying liquid refrigerant to the evaporator ld, but the refrigerant could enter the evaporator just as well in the manner shown in Figf ure l.

Figure 3 shows how the still can be located',`

above all other components in the system, mak- -ing it relatively simple to secure gravity flow Embodiment of Figure 4 The embodiment shown in Figure 4 has aspects of similarity to both Figures l and 2. The

corresponding parts are similarly numbered, using the distinguishing letter b.

The discharge 9b branches, one branch libc' passing to the condenser and the other branch 912sV passing to the oil still, but the discharge gas passing through the oil still enters the condenser through a connection ib, so that in one feature it resembles Figure land in the other Figure 2.

Instead .of an automatic ilow control valve -such as 26 or 26a, use is made of a manually adjusted ow control valve 44'which, however, must be set for a proper flow rate. The purpose of illustrating a manual valve in Figure 4 is to indicate the possiblity of its use here, and also in the structure of any of the gures, to control the rate of flow through the transfer coil. The` return of oil through the line 32h is by gravity as in Figure 2. The trap arrangement of Figure 1 obviously could be inserted in case of need.

In order to indicate the fact that the line I3b might enter the condenser i4b either directly or through the float chamber of iioat valve Hb, two stop valves 45 and 46 are indicated. The valve 45 controls a direct connection to the condenser. The Valve 46 'controls a connection to the chamber of float I'lb. The connectionsA` are functionally the same. Only one of the valves 45, 46 would be open at a time, and in a com- 75 mercial installation one or the other connection would be made and the other omitted. The purpose is to indicate on Figure 4 that either type of connection may be used.

Embodiment of Figure 5 Figure 5 differs from the other figures chiefly in the form of the evaporator and is included to make clear the fact that the invention is not limited to use with an evaporator having pump circulation and sprays.

'I'he general arrangement resembles Figure 4 in that the evaporator is above the still and the still is above the condenser, the oil being returned to the crank case by gravity. A trap can be used when the location of the compressor requires. Parts similar to those in other figures will be given the same reference numeral with the distinguishing letter c.

It will be observed that the high pressure line 9c branches, one branch Scc going to the condensery and the other branch 90s to the still.

With this explanation, the similarity of the parts numbered 6c to |8c Will be readily apparent. The parts 24e to 38e are also essentially similar in form and arrangement to those already described. However, the evaporator parts which are numbered I9 to 23 in Figure 1 are replaced by others, which will now be described.

The liquid line I8c leads to the valve element 5l of a low side float valve whose float chamber is indicated at 52 and is piped to a receiver suction trap.53. 'Ihis receiver suction trap takes the form of a vertical cylinder with a cylindrical baille 54 in its upper portion. Above this baiiie the suction connection 24e leads from the interior of the trap to the suction 8c of the compressor.

40 Thus the float in the chamber 54 corresponds to the liquid level in the receiver suctionxtrap 53 and controls ow of refrigerant directly from the liquid line |8c to a coil 55 in which the refrigerant is partly evaporated, the lower end of the coil discharging into the trap 53 opposite the baie 54. Thus the float valve'? operates to maintain a constant liquid level in the trap and the entering liquid is partly evaporated in an entrance coil 55. Leading from the bottom of the trap 53 is a flooded evaporator coil 56 which is shown as a simple zig-zag coil and which re-enters the trap above the liquid level and opposite the baille' 54. As is Well understood, active evaporation of refrigerant in the coil 56 will produce rapid circulation in that` coil. 'I'he effect of such evaporation is to increase the concentration of oil in the liquid in the drum 53. Part of this flows oir through the connection 25e under the con- 60 trol of the automatic flow control valve 26a. The control is at such a rate that the refrigerant is substantially completely evaporated in passing through the coil I5c, so that the refrigerant returns to the suction line 24e from chamber |6c by way of line 29c and oil ows by gravity back to the crank case 1c, as clearly indicated in the drawings.

A purge valve 5l is indicated in shell il. In this devicei as in all others illustrated, a

trap structure such as shown in Figure 2 can be inserted as indicated in Figure l, whenever necessary to deliver the oil to the crank case against reasonable gravity or pressure head.

All four embodiments above described have in common the idea of continuous distillation o:

refrigerant from oil by the use of heat derived from hot gas.

In Figure 1 al1 the hot gas passes through the still. In the remaining gures only a part of the hot gas passes through the still. 5

While hot gas from the compressor offers the best source of heat at suitable temperature, because it is in a sense waste heat and because it becomes available automatically .upon starting the compressor, other sources of heat at suit- 10 able temperature could be used. If such source be substituted, the idea of controlled continuous flow of liquid mixture from evaporator to suction line, while the system operates, ensuring complete evaporation of refrigerant, would still 15 be present.

Means, of which the illustrated trap is typical, may be used to return the oil against adverse pressure conditions. The various arrangements shown indicate that the still may be located in '20 a Wide range of positions relatively to the condenser and the evaporator.

Two distinct types of evaporator are illustrated, and the adaptability of the inventive concept of these two types is clearly disclosed. It is 25 similarly applicable to other specifically different types.

While it is impossible to illustrate every conceivable embodiment of the invention, suicient has been shown to indicate the versatility of the 30 scheme. By a conjoint use of various principles illustrated by the different figures, it is possible to meet almost any condition that may be encountered in practice.

The illustrations of evaporators, heat ex- 35 changers, etc., are conventional. Obviously the selection of any type of exchanger having extended surfaces is a matter of mechanical skill so far as the present invention is concerned. Consequently the descriptions given are general 40 and intended to be illustrative and not limiting. The scope of the invention is defined by the claims.

What is claimed is:

' 1. The method of operating a refrigerating 45 system of the compressor, condenser, evaporator circuit type using a volatile refrigerant and having a compressor lubricating means using a lubricant miscible with such refrigerant, which method comprises passing at least a portion of the 50 hot refrigerant gas compressed by the compressor in heat exchanging relation with oilrefrigerant mixture in which mixture the refrigerant is initially in the liquid phase, said mixture being continuously Withdrawn from the 55 I evaporator and subjected during such heat exchange to suction pressure of the circuit; limiting the rate of withdrawall of such mixture sufiiciently to assure that the refrigerant component thereof evaporates; returning said evap- 60 orated refrigerant to the suction of the compressor; and delivering the lubricant thus freed of refrigerant to the lubricating means of the compressor. i

2. The method of operating a refrigerating 65.

during such heat exchange to suction pressure of the circuit; limiting the rate of withdrawal of such mixture suiciently to 'assure that the re- I frigerant component thereof eyaporates;` returning said evaporated refrigerant to the suction of the compressor; and delivering the lubricant thus-freed of refrigerant. to the vlubricating means of the compressor.

refrigerant and comprising, a compressor.; a Vcondenser to which the compressor delivers com# pressed refrigerant; an; evaporator connected with the suction of said compressor; ow con trolling means for delivering refrigerant from. the condenser to the evaporator; lubricating means for said compressor operating substantially atsuction pressure in the system; an oil 'still comprising a separating A.chamber and a heat exchanger, the .latter havingtwo fiow paths the first of which deliversto Said chamber; connections, one leading from the upper vpor-tion of said chamber to the suction ofthe compressor and another from the lower portion of said chamber to said lubricating means; a flow control valve connected to deliver liquid refrigerant and lubricant from the evaporator at a restricted rate to said firstflow path; and means rendered effective upon operation of said compressor for circulating a heating uid through said 'second -flow path.

4. The combination with the structure d ened in claim 3; of a trap interposed in the connection between said chamber and said lubricating means; said trap including automatic valve mechanismfor subjecting the trap alternately to suction pressure inthe system to cause it to receive lubricant from said chamber and a high side pressure while isolating said trap from Said chamber to cause the transfer of lubricant from said trap to said lubricating means.

-5. A refrigerating circuit containing a volatile refrigerant and comprising, a compressor;

a condenserA to which the compressor deliversv compressed refrigerant; an evaporator connected with the suction of said compressor; flow controlling means. for delivering refrigerant from the condenserl to the evaporator; lubricating means for said compressor operating substantially at suction. pressure in the system; an oil still comprising a separating'chamber and a' heat exchanger, the latter having twoflow paths the first of Whichdelivers to said chamber; connections, one leading from the upper vportion of said chamber to the suction of the compressor and another from thev lower portion of said chamber toV said lubricating means; a flow control valve connected to deliver liquid refrigerant and lubricant from the evaporator at a restricted rate to said first flow path; and connections for passing at least a part of .the refrigerant delivered by the-compressor through said second ow path. Y

6. The combination with the structure dened in claim 5 and so arranged that said second path is interposed in a by-pass from the discharge of the compressor to the high sideof the system without passing through the condenser, of an automatic valve arranged to inhibit the discharge of vaporous refrigerant fromsaid second path to said'high side of the system.

7. A refrigerating circuit containing a volatile refrigerantand comprising, a compressor; a condenser to which the compressor delivers compressed refrigerant; an evaporator connected with the suction of said compressor; ow controlling means for delivering liquid refrigerant from the condenser to the evaporator; lubricating means for said compressor operating substantially at suction pressure in the system; an oil still comprising a separating chamberv and a heat exchanger, the latter having twofiow paths,

the first of which delivers to said chambr; connections one leading from the upper` portion of` said chamber' to the suction of the compressor and another from the lower portion of said chamber to said lubricating means; a flow control valve of the superheat control type connected to deliver liquid Vrefrigerant and lubricant from the evaporator to said Afirst now path and arranged to control the supply inv such a way that refrigerant leaving saidseparating chamber is completely evaporated; and connections for passing at least va part of the refrigerant delivered by the compressor through said second flow path.

` 8. A refrigerating circuit containing a volatile refrigerant and comprising, a compressor; a condenser to which the compressor delivers compressed refrigerant; an evaporator connected with the suction of said compressor; flow controlling means for delivering refrigerant from the condenser to the evaporator; lubricating means for said compressor operating substantially at suction pressure in the system; an oil still comprising a separating chamber and a heat exchanger, the latter having two flow paths, the rst of which delivers to said chamber; connections one leading from the upper portion of said chamberto the suction of the `compressor and another from the lower portion of said chamber to said lubricating means; a flow control valve connected to deliver liquid refrigerant and lubricant from the evaporator at a restricted rate to said rs't ow path; and connections whereby refrigerant compressed by the compressor and flowing to the condenser ows through said second flow path.

9. The combination defined in claim 8, in which all the refrigerant compressed by the compressor flows vto the condenser through said second path.

- for said compressor operating substantially at suction pressure in the system; an oil still comprising a separating chamber and a heat exchanger, the latter having -two flow paths, the first of which delivers to said chamber; connections one leading from the upper portion of said chamber to the suction of the compressor and another from the lower portion of said chamber to said lubricating means; a ow control valve of the superheat control type connected to deliver liquid refrigerant and lubricant from the evaporator to said first flow path, said flow control valve being so arrangedqthat refrigerant leaving said separating chamber is evaporated;` and connections for passing refrigerant compressed by the compressor and flowing to the condenser through said second flow path.

tor and subjected during such heat exchange to suction pressure of the circuit; varying the rate of withdrawal of such mixture independently of perfomance ofthe evaporator to maintain practically the maximum permissible withdrawal rate consistent with substantially complete evaporation of the refrigerant component of the mixture so withdrawn; returning said evaporated refrigerant to the suction of the compressor; and delivering the lubricant thus freed of refrigerant to the lubricating means of the compressor.

WALTER E.Y BELINE.

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