High Pressure Multiple Pump For Absorption Refrigeration Machine

Abstract

A pump for circulating a plurality of fluids in an absorption refrigeration machine, the pump having a plurality of fluid impellers, at least two of which are arranged in series.

Description

BACKGROUND OF THE INVENTION

Pumps are commonly associated with absorption refrigeration machines in order to convey the various fluids used in the machine from one point in the system to another. Thus it is not uncommon for an absorption machine to employ three distinct pumps. One such pump normally circulates absorbent solution between the absorber and the generator or concentrator. A second pump normally circulates absorbent solution within the absorber section, such as from a drain pan to a spray header or drip pipe located above the absorber tube bundle. Yet another pump may circulate refrigerant within the evaporator section of the machine in a similar manner.

Certain unique advantages can be gained by consolidating the aforementioned three pumps into a single, multi-stage pump driven by a single source of motive power. Such a multi-stage pump is described in U.S. Pat. No. 3,296,823, issued Jan. 10, 1967. However, the pump disclosed in that patent may not be satisfactory for use in an absorption machine having a high pressure generator, such as a multi-stage absorption machine, because the size of the impeller required may vary considerably from one pump stage to another.

SUMMARY OF THE INVENTION

It is an object of the present invention, therefore, to provide a pump that may be used on a high pressure type of absorption machine.

It is a further object to provide a pump having a plurality of impellers driven by a single power source.

Other objects and advantages will become obvious as the specification proceeds.

The present invention provides a pump for an absorption refrigeration system, the system including an absorption refrigeration machine having a generator, a condenser, an evaporator, an absorber, a refrigerant and a solution capable of absorbing the refrigerant. A multiple pump is provided for circulating refrigerant and absorbent solution as required for the operation of the machine. The pump has a plurality of impellers wherein separate impellers may circulate different fluids between diverse portions of the machine. At least two of the impellers are serially arranged and adapted to transfer absorbent solution between the absorber and the generator.

DESCRIPTION OF PREFERRED EMBODIMENTS

Certain preferred embodiments of the present invention will be described in greater illustrative detail and with particular reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic sectional view of an absorption refrigeration system including the fluid circulating system,

FIG. 2 is a front elevation view in vertical cross-section of the pump used in the present system.

Referring now to FIG. 1, the absorption system shown is of the type having a single shell 10, a partition 11 separating a first generator stage from a second generator stage 12 and a condenser 14. Partition 16 further separates the second stage generator and condenser section from a low pressure chamber containing an evaporator 18 and an absorber 20. It should be understood that other arrangements might be used; for instance, the first stage generator 13 might be contained in a single shell with the remaining components in a second shell. Alternatively the generators of 13 and 12 and the condenser 14 might be in one shell and the absorber 20 and evaporator 18 might be in a second shell with conduits therebetween for conducting fluids.

Various combinations of refrigerant and absorbent may be used. A solution of lithium bromide and water has been found to be highly satisfactory.

The absorber 20 has a coil 22 supplied with cooling fluid from a source 24 to remove the heat from the absorber. The cooling fluid is conducted by conduit 26 to a cooling coil 28 in the condenser 14 and the cooling fluid leaves the machine through a conduit 30. The cooling coil 28 in the condenser 14 removes the heat from and condenses the refrigerant vapor in the condenser.

The first stage or high pressure generator 13 has a heating coil 31 supplied with heating fluid from a source 33. The heating fluid is discharged from the coil through conduit 35. The coil 31 heats the absorbent solution in the generator 13 causing it to boil whereby refrigerant vapor is released therefrom. The refrigerant vapor passes through conduit 32 and through the coil 34 of the second stage or low pressure generator 12. The refrigerant vapor condenses and releases heat to further concentrate intermediate strength solution present in the second stage generator 12. The refrigerant then passes to the condenser 14 via conduit 36, flow of refrigerant being controlled by restrictor 38.

The condensed refrigerant in the condenser 14 flows through an opening 40 into the evaporator 18. The absorbent solution in the absorber 20 reduces the pressure in the absorber 20 and in the evaporator 18 by the absorption of refrigerant vapor, thus causing the refrigerant in evaporator 18 to boil. A low temperature is thus maintained in the evaporator 18.

Evaporator 18 has a coil 42. Fluid from a refrigerating load such as an air conditioning system enters coil 42 through conduit 44. This fluid is reduced in temperature in the coil 42 and returns to the refrigerating load through conduit 46.

The liquid refrigerant in the evaporator 18 collects in a pan 50, and flows from the pan via conduit 52 to a pump indicated generally at 60, and specifically to an impeller portion 62 of the pump 60. Pump 60 may be driven by any suitable motor means 130. The liquid refrigerant is discharged by pump 60 through conduit 54 from which it flows through nozzles 56 into an evaporator 18.

Dilute solution flows from the absorber 20 through conduit 58 to pump 60, and specifically to impeller portion 64. The solution is discharged from impeller portion 64 through conduit 66 and to a second impeller portion 68. It can be seen, therefore, that impeller sections 64 and 68 are thereby arranged in series. The dilute solution is discharged from pump 60 through conduit 70 which conducts the fluid to heat exchanger 71 from which it flows through conduit 72 to heat exchanger 73 and from there through conduit 74 to the high pressure generator 13.

The dilute solution is partially concentrated in generator 13 by the boiling off of refrigerant as herein before described in detail. The intermediate strength solution is withdrawn from generator 13 via conduit 76 and passes through heat exchanger 73 from which it is conducted through conduit 78 to the second stage generator 12.

The intermediate solution is further concentrated in generator 12 and is withdrawn therefrom via conduit 80 and passes through heat exchanger 71, conduit 82, and into conduit 84. Dilute solution from the absorber 20 passes into conduit 84 wherein it is mixed with the concentrated solution passing from conduit 82 and the resulting mixture enters pump 60 and specifically impeller portion 65, exiting from pump 60 via conduit 86. From conduit 86 the intermediate strength solution is sprayed from nozzles 90 over the tube bundle in absorber 20.

Pump 60 has a pump body 91 and end walls 92 and 93. Attached to end plate 92 is a bearing housing 94, and at the opposite end of pump 60, bearing housing 95 is mounted to transverse portion 96 of pump body 91. Bearing 97 is carried by bearing housing 94 and bearing 98 is carried by bearing housing 95. Shaft 99 is rotatably mounted in bearings 97 and 98.

A refrigerant impeller 62 is mounted on shaft 99 to rotate therewith. Pump 60 has an inlet passage 100 in fluid communication with conduit 52 and impeller 62. A discharge passageway 101 is in fluid communication with impeller 62 and conduit 54. A labyrinth seal 102 provides the seal between the discharge passage 101 and the inlet passage 100, thus creating the differential pressure for flow through passage 103 to chamber 105 and bearing 98 and through passage 104 back to the suction side of impeller 62. Chamber 105 also provides cooling for seal 106.

Threaded into discharge chamber 101 is conduit 107 shown terminating in valve 108. Valve 108 may be used to open discharge passageway 101 to the air during servicing of pump 60 if desired. However, it is preferred to extend conduit 107 around to the pump motor 130 in order to provide refrigerant to the motor for cooling.

An absorption solution impeller 65 is mounted on shaft 99 to rotate therewith, on the end of pump 60 opposite impeller 62. Pump 60 has an inlet passage 108 in fluid communication with conduit 84 and impeller 65. A discharge passageway 109 is in fluid communication with impeller 65, conduit 86, and conduit 110 which terminates in valve 112. Valve 112 is normally closed but may be opened to admit air to pump 60 during servicing.

In the approximate center portion of pump 60 impellers 64 and 68 are mounted in back-to-back relationship on shaft 99 for rotation therewith. Pump 60 has an inlet portion 114 in fluid communication with conduit 58 and impeller 64. A discharge passageway 16 is in fluid communication with impeller 64 and conduit 66. Conduit 118 is in fluid communication with narrower upper portion of discharge passageway 116, and said conduit is shown terminating in valve 119, which is normally closed and may be opened during servicing and the like as hereinbefore described in connection with similar vent valves.

Conduit 66 communicates with discharge passageway 116 and with inlet portion 120, which inlet portion is also in fluid communication with impeller 68. Accordingly, the discharge from impeller 64 is introduced to the suction side of impeller 68, thereby arranging these impellers in series. Impeller 68 is also in fluid communication with discharge passageway 122 which in turn is in fluid communication with conduit 70. In this manner, the dilute solution from absorber 20 is conveyed to the high pressure generator 13 via impellers 64 and 68 of pump 60, whereby the discharge pressure from impeller 68 is greater than the discharge pressure from impeller 64, thereby enabling pump 60 to satisfy the pressure requirements of a high pressure generator as may be found in a two-stage absorption machine. At the same time, the size of the impellers 64 and 68 remains compatable with impellers 62 and 65 so that the entire pump assembly can be driven by a single motor. Conduit 115 is in fluid communication with the narrower upper portion of discharge passageway 122, and terminates in valve 117 which functions in the same manner as the other vent valves such as valves 112 and 119 previously described.

An electric motor 130 may be mounted at end of shaft 99 which protrudes beyond the pump housing. It is desired to route lubricant from the motor lubrication system through chamber 125 to bearing 97 for lubrication thereof. Seal 127 is provided between bearing 97 and inlet portion 108.

While the invention has been described in considerable detail, it will be understood that such detail is for the purpose of illustration and not by way of limitation, and that the scope of the invention is delineated in the appended claims.

Claims

I claim:

1. An absorption refrigeration system comprising a first stage high pressure generator, a second stage low pressure generator, an absorber, an evaporator, a condenser, an absorbent solution, a refrigerant, and pump means for moving said absorbent solution and said refrigerant within said system; said pump means including a shaft having a motor drivingly connected thereto, a first impeller mounted at one end of said shaft to receive refrigerant from a first portion of said evaporator and transfer said refrigerant to a second portion of said evaporator; a second impeller mounted on said shaft at the end opposite said first impeller to receive absorbent solution from a first portion of said absorber and transfer said solution to a second portion of said absorber; a third impeller mounted on a central portion of said shaft to receive absorbent solution from said absorber and transfer said solution to a fourth impeller, said fourth impeller mounted on a central portion of said shaft to receive said solution form said third impeller and transfer said solution to said first stage high pressure generator, all of said impellers being mounted in a common housing whereby all of said impellers are driven by said motor.