US2303817A - Refrigeration - Google Patents

Description

Dec. 1,1942. I e. A. BRACEVI I I 2,303,817

REFRIGERATION- Filed Feb. 5, 1940 INVENTOR 6601296 48 Brace ATTORNEY 'cludes the absorber and boiler.

Patented Dec. 1, 1942 REFRIGERATION George A. Brace, Winnetka, 111., assignor to The Hoover Company, North Canton, Ohio Application February 5, 1940, Serial No. 317,382

13 Claims.

This invention relates to the art of refrigeration and more particularly to a novel absorption refrigerating system involving unique control and regulating features.

. This invention particularly relates to threefluid absorption refrigerating systems of the type in which a circulating motor is hermetically sealed within the system inorder to circulate the fluids therein contained. In systems of this type it is customary to utilize a fluid fuel burner for the purpose of applying heat to the boiler to produce refrigerant vapor therefrom which is subsequently condensed and then evaporated in the presence of an inert pressure equalizing medium. When the control mechanism of such a system responds to a demand for refrigeration to energize the circulating motor and to actuate the fuel control mechanism of the burner in order to place a full or running flame thereon, a considerable period of delay occurs due to the fact that the burner must first heat the boiler and its contents to the boiling point before ex-. pelling refrigerant vapor therefrom; however, the circulating motor is in operation and serves to circulate the pressure equalizing medium through its circuit which includes the evaporator and the absorber and the absorption solution is likewise circulated through its circuit which in- As a consequence of this condition the period required to bring the boiler into operation is appreciably lengthened by reason of the fact that solution is continually being withdrawn therefrom, cooled in the absorber and then returned to the boiler assembly. Also due to the fact that the inert gas is circulating between the absorber and the evaporator heat is applied to the 'gas in the absorber which is then conveyed into the evaporator, thus increasing the demand for refrigeration and also increasing the ultimate load which the system will have to carry once the boiler is brought into full operation.

Accordingly, it is a principal object of the present invention to provide a three-fluid absorption refrigerating apparatus involving a heater for the boiler and a fluid circulator in which the operation of the circulator is delayed with respect to the operation of the boiler heater in order to permit the boiler to come into full operation prior to circulation of the pressure equalizing medium and absorption solution.

t is a still further object of the present invention to provide an absorption refrigerating system of the above referred to type in-which ;he control mechanism only directly energizes the heater for the boiler and in which the circulator is energized only in response to a change in the condition of a portion of the system such as to indicate that the boiler has then reached full operation.

It has been found in the past that in absorption refrigerating systems of the type here under consideration considerable vapor will beexpelled from the boiler, condensed in the condenser and discharged into the evaporator after de-energization of the boiler heater by the control mechanism. Such vapor is of course produced by residual heat in the boiler-analyzer assembly and its component parts and in the,

insulating jacket. At times-this discharge may be great enough to flow into the evaporator drainage system and then flow to waste.

Accordingly it is a further object of the present invention to provide an absorption refrigerating system of the character referred to above in which the control mechanism exercises direct control only over the boiler-heater and in which the circulating motor continues operation after de-energization of the heater for the boiler a period of time suflicient to evaporate the residual refrigerant liquid produced after de-energization of the boiler heater.

Other and further objects of the invention will become apparent as the description proceeds when taken in connection with the accompanying-drawing in which the single figure is a diagrammatic representation of 'a three-fluid absorption refrigerating system embodying the present invention.

In the accompanying drawing there is illustrated a three-fluid absorption refrigerating system comprising a boiler B, an analyzer D, an air-- cooled rectifier R, a tubular air-cooled condenser C, an evaporator E, a gas heat exchanger G, a tubular inclined air-cooled absorber A, a liquid heat exchanger L, a. solution reservoir S, and a circulating fan F which is driven by an electrical motor M. These elements are suitably connected by various conduits to form a plurality of gas B generates refrigerant; vapor from the solution therein contained. The vapors so generated pass upwardly through the analyzer D in counterflow to the strong solution flowing downwardly therethrough. After traversing the analyzer D the vapor is conveyed from the upper portion thereof to the upper portion of the condenser C by means of a conduit H which includes the rectifier R.

Thelean solution formed in the boiler by the generation of refrigerant vapor therefrom is conveyed from the boiler to the solution reservoir S by way of the conduit I2, the liquid heat exchanger L, and a finned looped conduit |3 which also serves as a solution precooler.

The solution reservoir S is vented by means of a conduit H which connects to the suction conduit I 5 of the circulating fan F. The conduit l5 extends betweenthe suction side of the fan F and the upper portion of the absorber A.

The lean solution is conveyed from the reservoir S to the conduit ['5 adjacent its point of connection with the absorber A by means of a gas lift pumpingconduit l6. Pumping gas is supplied to the conduit l6 by means of a conduit I! which is connected between the discharge conduit I8 of the circulating fan F and the gas lift pump 16 below the liquid level normally prevailing therein and irr the solution reservoir S.

The lean'solution flows downwardly through In its traverse through the absorber the lean solution absorbs refrigerant vapor from the gas mixture flowing therethrough and the resulting which is supported in the-condenser side of the conduit 24.

The evaporator E may be of any desired type of construction. However, as diagrammatically illustrated herein, it is of the type in which the high velocity gas stream flowing through the evaporator'serves to sweep -or drag liquid refrigerant upwardly therethrough as it is evaporating to produce refrigeration. A preferred construction of this type evaporator is disclosed and claimed in the co-pending application of Curtis C. Coons and William H. Kitto, Serial No. 220,189, filed July 20, 1938.

An anti-blocking and overflow drain 2'! is connected between the upper portion of the bottom conduit in the evaporator E and the strong solution return conduit l9.

Theliquid refrigerant supplied to the bottom portion of the evaporator E meets a high velocity gas stream flowing upwardly therethroughwith the result that the liquid refrigerant is propelled upwardly through the evaporator as it is evaporating into the gas stream to produce useful refrigeration.

The top portion of the evaporator is provided with a large diameter finned box-cooling conduit 28 into which both the liquid and gas discharge. The gas slows at a slow rate through this conduit, hence the same is inclined rearwardly in order to permit liquid to flow by gravity. The resulting rich gas and unevaporated material in the evaporator is conveyed from the conduit 28 heat of absorption is rejected by the cooling fins means of the conduit IS. The inert gas is placed under pressure in the fan F and is then conveyed therefrom to'the lower portion of the evaporator E by way of the conduit l8, the outer path of the gas heat exchanger G, and an evaporator gas supply conduit 22.

The refrigerant vapor which is supplied to the condenser C is liquefied therein by heat exchange relationship with atmospheric air and is then into the rich gas side-of the gas. heat exchanger G by means of .a conduit 29. After traversing the rich gas side of the gas heat exchanger the rich gas and unevaporated material is drained therefrom into the bottom portion of the ab-- sorber A by means of the conduit 30. Thus, the conduit 30 serves as a rich gas return conduit and as an evaporator drain. The rich gas then flows upwardly through the absorber A in conduit iii in a manner such that it cannot reach conveyed therefrom to the bottom portion of the evaporator E by way of the conduit 23 and a conduit 24 which includes a downwardly extending U-shaped looped portion which is designed to vailing in the condenser and the condenser side of the conduit 24 is that prevailing on the discharge side of the evaporator whereas the pressure prevailing on the discharge side of the conduit 24 is that prevailingatthe inlet to the evaporator; This pressure difference is compensated by a pressure-balancing liquid column the circulating fan and the fan is so connected to the absorber that lean solution cannot be conveyed thereinto from the lean solution supply lines. I

The gas burner H is supplied with gaseous fuel by means of a supply conduit 40 which includes the solenoid valve V, and a thermostatic safety cut-off mechanism 4| which is arranged to discontinue all supply of fuel to the burner H upon failure of flame thereat. A small by-pass '42 is provided around the solenoid shut-oi! valve V in order to maintain a small igniting or pilot flame on the burner H even though the valve V be in directed into a central tube 45 which passes through the .boiler B and then communicates with asuitable disposal flue 48.

The apparatus is controlled by means of a thermostatic electrical switching mechanism 48. Such switching mechanisms are well known in the art and it is therefore considered unnecessary to disclose the same in detail. .It is of the usual type which makes and breaks an electrical circuit in response to predetermined temperature changes. The switching mechanism 48 is arranged to'be responsive to the temperature at lary conduit 49 and thermostatic bulb 50.

Electrical energy is supplied to the control mechanism through a pair of electrical conductors 52 and 53. The electrical conductor 52 connects directly to the control mechanism 48 and is also connected directly to the circulating motor M by means of an electrical conductor 54. The circulating motor M is connected by means of a conductor 55 to the movable contact 56 of a snap-acting switching mechanism 57. The stationary contact 58 of the switching mechanism is connected by means of a connector 59 to the solenoid valve V and to the supply conductor 53. The switching mechanism 88 and the solenoid valve V are also connected together by means of an electrical conductortfl, thus completing the electrical control circuit for the apparatus.

The switching mechanism 51 includes a thermostat 52 which as illustrated is positioned to be responsive to the thermal condition of a portion of the conduit l l removed from the boiler B. The thermostat 62 actuates a snap-acting toggle mechanism 63 of which the movable contact 55 of the switch 57 is a part. The movable contact 56 of the switching mechanism 51 is actuated between the closed circuit position shown in which the arm 56 is in contact with the contact 58 and the open circuit position in which the arm 55 rests against a suitable stop (it. The thermostatic switching mechanism 51 may be housed within a suitable casing which is indicated'generally in dotted lines at 55.

The operation of the invention, except insofar as the same has already been described in connection with the refrigerating system per se, is as follows: Assuming a demand for refrigeration the thermostatic mechanism 48 will close the electrical circuit-between the conductors 52 and 50 thereby energizing the solenoid valve V which will-move to open position and allow free flow of fuel through the conduit 40 to the burner H. The burner H will now carry a high flame which will apply heat to the boiler B at a rate suflicient to generate refrigerant vapor therefrom after the boiler has been brought up to the boilingpoint. After the contents of the boiler are brought to the boiling point hot vapors will begin to flow through the conduit II to the condenser. During this period of time, however, the motor M is de-energized because the conduit II is cold and the thermostat 62 has actuated the snap acting toggle switch arm 56 into its open circuit position adjacent the stop 64. Therefore, the inert gas is not circulated by the fan, and no absorption solution is circulated since the gas lift pump l5 cannot receive pumping gas through the conduit H.

As the boiler begins to discharge vapor the temperature of the pipe II will increase and the thermostat 62 will move from the dotted line position shown to the solid line position shown to actuate the movable arm 56 of the switch against the contact 58 just after the boiler has gone into full operation; that is, discharging refrigerant vapor at the normal operating rate through the conduit II and hencethe condenser C.

When the switch arm 56 contacts the switch contact 58 the motor is energized through the following circuit: 52, 54-, M, 55, 56, 58, 59, 53. The actuation of the switching mechanism 51 has no effect upon the energization of the solenoid valve V which continues in open position mere ignition or pilot flame.

as before under the control of the mechanism 48. The apparatus is now in running condition and continues to operate producing refrigeration until suchtime as the temperature at or adjacent the evaporator E is reduced to the value for which the thermostatic mechanism 48 is set, at which point the circuit between the electrical conductors 52 and '60 is broken by the mechanism 48 and thevalve'V returns to the closed position, thus reducing the flame on the burner H to a At this point, however, the motor M continues to operate and to circulate the pressure equalizing medium and absorbing solution. This is because of the fact that the conduit ll remains at an elevated temperature after the burner H is reduced t a mere ignition flame. The period of time required for the conduit II to cool sufiiciently to actuate thethermostat 52 to shift the switch arm 58 against the stop 64 thereby open-circuiting and de-energizing the motor M is approximately the period of time required to condense and evaporate and absorb vapor expelled from the boiler B after deenergization of the solenoid valve V, thus preventing refrigerant liquid discharginginto the evaporator after closure of the valve V from running to waste through the drain 21 in the event that sufficient liquid will accumulate in the bottom of the evaporator to reach the level of the drain. I

It will be appreciated that the thermostatic switching mechanism 51 need not be responsive to the temperature of the vapor line I l as it could also be responsive to the temperature condition of the flue 46, the liquid conduit 24, the condenser ,C, or of any other portion of the system whose thermal condition changes synchronously but in time lag relationship with the energization and de-energization of the solenoid valve V, whereby the circulating motor M will not be started until the boiler has come into operation and will not be stopped until a short period after de-energization of the burner in order to permit evaporation of vapor produced after such deenergization and of vapor and liquid within the condenser-evaporator supply system.

The present invention thus provides a highly efficient and flexible absorption refrigerating system in which the boiler is brought into full operation before the refrigerant, inert gas and absorption solution are circulated. Also the refrigerant, inert gas and absorption solution are circulated after the heat source of the boiler is rendered inoperative in order to evaporate resiand to evaporate refrigerant liquid produced by residual heat in the boiler assembly after the heater is tie-energized.

While I have shown but one embodiment of my invention, it is to be understood that this embodiment is to be taken as illustrative only and not in a limiting sense. I do not wish to be limited to the particular structure shown and described but to include all equivalent variations thereof except as limited by the claims.

I claim:

1. Absorption refrigerating apparatus includinga boiler, a heater for said boiler, an electrically operated fluid 'circulator, refrigeration demand responsive control means arranged to control the operation of said heater, and means responsive to a change in the thermal condition of a portion of the apparatus induced as an incident to achange in the operative condition of said heater for governing'the operation of said circulator.

2. Absorptionrefrigerating apparatus including a boiler, a vapor discharge conduit therefor, a heater for said boiler, anelectrically operated fluid circulator, refrigeration demand responsive control means arranged to render said heater operative and inoperative in accord with the refrigerating demand, and means responsive to changes in the thermal condition of said vapor discharge conduit for governing the operation of said circulator.

3. Absorption refrigerating apparatus comprising a generator, a liquefier, an evaporator, and a fluid circulator connected in circuit, an elec- .trically operated prime mover for driving said rator and an absorber, a solution circuit including a'generator and said. absorber, means for heating said generator, means for regulating the operation of said heating means in accord withthe demand for refrigeration, electrically operated means for circulating the inert gas and solution through said inert gas and solution circuits respectively, and means responsive to the thermal condition of a part of said apparatus arranged to receive refrigerant vapor from said boiler for controlling said electrically operated means.

5. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporator and an absorber, an absorption solution circuit including a generator and said absorber, means for liquefying refrigerant vapor produced in said generator and for supplying the liquid to said evaporator, means for heating said genera tor, refrigeration demand responsive means for controlling said heating means, electrically operated means for circulating inert gas through said inert gas' circuit, and means responsive to a ,sponsive mal condition of a portion of said refrigerant liquefying and supplying means for controlling said circulatin means.

8. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporator and an absorber, an absorption solution circuit including a generator and said evaporator, means arranged to receive refrigerant vapor from said generator to liquefy the vapor and to supply the liquid to said evaporator, means for heating said generator, refrigerating demand remeans for controlling said heating means, means for circulating inert gas through said inert gas circuit, means responsive to a condition produced by the operation of said heating means for controlling said circulating means, and thermostatic means arranged to be responsive to the temperature of a portion of said firstmentioned means for controlling said-circulating means.

9. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporator and an absorber, an absorption solution circuit including a generator and said evaporator, means arranged to receive refrigerant vapor from said generator to liquefy the vapor and to supply the liquid to said evaporator, means for heating said generator, refrigerating demand responsive means for controlling said heating means, means for circulating absorption solution through said absorption solution circuit, means responsive to a condition produced by the operation of said heating means for controlling said circulating means, and thermostatic means arranged to be responsive to the temperature of a portion of said firstmentioned means for controlling said circulating means.

10. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporacondition produced by the operation of said heating means for controlling said circulating means.

6. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporator and an absorber, an absorption solution circuit including a generator and said absorber, means for liquefying refrigerant vapor produced in said generator and for supplying the liquid to said evaporator, means for heating said generator, refrigeration demand responsive means for controlling said heatin means, electrically operated means for circulating absorption solution through said absorption solution circuit, and means responsive to a condition produced by the operation of said heating means for controlling said circulating means. i

7. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporator and an absorber, an absorption solution circuit including a generator and said evaporator, means for liquefying refrigerant vapor produced in said generator and for supplying the liquid to said evaporator, means for heating said generator, refrigerating demand responsive means for controlling said heating means, means for circulating inert gas through said inert gas circuit,

and thermostatic means responsive to the thertor and an absorber, an" absorption solution circuit including a generator and said absorber, a condenser, a vapor line connecting said generator to said condenser, means for conveying liquid refrigerant from said condenser to said evaporator, means for heating said generator,'means for rendering said heater operative and inoperative in accordance with refrigeration demand, a motor driven fluid clrculator in' said apparatus, and

' means responsive to'the temperature of said vapor line for controlling said circulator.

11. Absorption refrigerating apparatus comprising a boiler, a liqu'efler, an evaporator and an absorber connected in circuit, said apparatus including a fluid circulator, an electrical device for driving said circulator, means for heating said boiler, refrigeration demand responsive means arranged to control said heating means, and means responsive to a change in the condition of a part of said circuit induced as a consequence of operation of said heating means for energizing said electrical device.

12. Absorption refrigerating apparatus comprising a boiler, a liquefler, an evaporator and an absorber connected in circuit, said apparatus including a fluid circulator, an electrical device for driving said circulator, means for heating said boiler, refrigeration demand responsive means arranged to energize and de-energize said heating means, and means responsive thermal condition of a portion of said apparatus induced as an incident to the operation of said heating means for energizing and de-energizing said electrical device in time delayed relaof said heating means.

to a change in the.

13. Absorption refrigeratingv apparatus comprising a boiler, a .liquefler, means for conducting vapor irom'said boiler to 'saidliquefler, an evaporator and. an absorber connected in circuit.

said apparatus including'a fluid circulator, an 5 electrical device for driving said circulator, means for heating said boiler, refrigeration demand responsive'means arrangedto start and stop said heating means, and means responsive to the thermal condition or said vapor conducting means for energizing said electrical device when saidboiler produces vapor and for de-energizin: said electrical device when said holler ceases to produce vapor.

GEO. A. BRACE.

Bar 1, 1942. Disclaimer filed April 12, 1943, by Company.

Di-'3'LAIMER' -George A. Brace, Winnefka, I11. REFRIGERATION. Patent dated Decemthe assignee, The Hoover Hereby enters this disclaimer to claims 8 and 9 in said specification.

0W 'G zeue May 4, 1943.

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