US2035814A - Refrigeration system - Google Patents

Description

March 31, 1936. F. L. KALLAM- REFRIGERATION SYSTEM COMEfl/R' COOLED FLUID HEflT/NG F LUID F ma m w L 0 W H) Y B 7 Filed March 14, 1932 A TTORNEY.

Patented Mar. 31, 1936 lTEsD STATES PATENT OFFICE 8 Claims.

The invention relates to a refrigeration system utilizing the principle of jet compression in a closed circuit.

An object of the invention is to provide an improved refrigeration system of the character described wherein but one fluid 'is utilizedin the refrigerant circuit.

Another object of the invention is to provide a refrigeration system wherein the operating to pressures are arranged to be relatively high,

thereby providing a particularly high degree 0 operative eiiiciency for the system. g A further object is to provide a refrigeration system adapted for the use therein of a refrigerant fluid lacking a fired boiling point.

A more specific object is to provide an improved refrigeration system which, while of general application, is particularly adapted for use in connection with a plant for refining mineral oils, the particular adaptation arising through the possible use inthe system of both a product and heat which are normally wasted in such a plant.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth or be apparent in the following description of a typical embodiment of the invention which is illustrated in the accompanying drawing, in which,

Figure 1 is a diagrammatic showing of a system embodying the present'invention.

Figure 2 is an enlarged sectional view of a jet compressor element of the system.

As particularly illustrated, the features of frigeration system wherein a boiler 5, a jet compressor 6, condenser 7, pump 8 and evaporator 9 comprise the principal operative elements, said elements connected to provide-a closed circuit for a refrigerant II which is alternately gasified and liquefied as it circulates through the system.

' The boiler 5 may be of any conventional type,

but for a reason to be hereinafter brought out the present boiler is disclosed as a heat exchanger wherein heated fiuid which is to provide the heat thereat is supplied through connecting pipes I2 of a circuit which is independent of the refrigerant circuit. A pipe I3 conducts gasified refrigerant from the boiler to the jet compressor 6, and means are preferably provided to insure constant temperature and pressure conditions in said pipe. As particularly shown, a valve 14 is provided in a heat supply pipe l2 of the boiler and said valveis controlled by a suitable thermostat l5 which is inserted in the pipe l3 and 'is controlled by the temperature of the gas in 'said pipe. A back pressure valve i6 is interposed-in the pipe I3 adjacent the jet compressor "6, said valve being shown as of the diaphragm the present invention are incorporated in a remotor type and arranged to have its setting automatically controlled by the pressure behind it, whereby the pressure in the pipe 53 may be maintained at a constant value.

Fluid discharged from the jet compressor 6 is conveyed to the condenser I through a pipe IT. The condenser! may be of any suitable type and is particularly shown as provided with condensing and accumulating chambers l8 and I9 respectively. A pipe 2| leads to the pump 8, said pump being arranged to be power driven as by an electric motor 22. The liquid from the condenser chamber I9 is delivered from the pump to the boiler 5 through a pipe 23 to thereby complete the circuit which includes the boiler.

It will now be noted that the present arrangement of apparatus is particularly adapted for cooling a, circulating fluid. Accordingly, the evaporator 9 is shown as comprising a heat exchanger providing a closed evaporation chamber 24 to contain liquid refrigerant and the vapor thereof, and having therein a coil 25 connected by means of pipes 26 in a circuit (not otherwise shown) carrying the liquid to be cooled. The evaporator 9 is arranged tobe supplied with liquefied refrigerant from the condenser through a pipe 21, said pipe having an expansion valve 28 interposed therein, the latter being arranged for variable adjustment of its setting, A pipe 29 delivers gasified refrigerant from the evaporator 9 to the low pressure intake of the jetcompressor 6. A back pressure valve 30 is interposed in the pipe 29, said valve being similar to the valve l6 whereby to automatically control the discharge pressure of the gasifled refrigerant to the jet compressor 8.

Referring to'Figure 2, wherein is shown the structure of the element 6 which is hereinbefore referred to as a jet compressor, said element is seen to be formed generally as an ejector, receives a gaseous stream of propelling fluid through the pipe [3, and discharges said stream as a jet from a nozzle 3| thereof through a Venturi orifice 32 and so into the pipe IT. The aforesaid propelling stream traverses a chamber 33 of the member 6 and said chamber is connected with the pipe 29, the flow of gaseous fluid from the pipe 29 and through the chamber 33 being induced by the aforesaid propelling stream through the member 6. Since the action in the element 6 discharges the entrained refrigerant gas from the evaporator at a considerably increased pressure thereof and for discharge into the condenser at such increased pressure, said element is understood to operate as a jet comand wherein the temperature of large quantities of products must be lowered below that obtainable with atmospherically cooled water. In such plants, an excess of reflux fluid is usually produced, and such a fluid is usually composedlargely of propane or butane and is adapted for use as a refrigerant since the hydrocarbons propane and butane possess physical characteristics which permit the use of high suction pressures and low compression heads therewith, a fact which is of particular advantage when employing the jet compression principle in a refrigerating circuit. A further feature of interest in the use of propane as a refrigerant is the fact' that propane has been found to be no lesseflicient in a refrigeration system than are ammonia or sulphur dioxide.

If-pure propane is to be used as a refrigerant in the present system, the most desirable condition would be to vaporize the same in the evaporator 9 at an absolute pressure of '78 pounds per square inch, this resulting in a corresponding temperature of 40 degrees Fahrenheit. For insuring a most vefiicient further handling of this gasifled refrigerant, it would be necessary that the same be compressed to an absolute pressure of 142.8 pounds per square inch for subsequent condensing at a temperature of not over 80 degrees Fahrenheit. To create the foregoing conditions and relations by means of the jet compressor 6 it is found that if the absolute boiler pressure is 500 pounds per square inch it would require the pressure flow of 2.02

pounds of propane through the jet compressor nozzle 3| to remove and compress one pound of propane vapor from the evaporator. It is noted that the figure 2.02 is numerically equal to the operative ratio of the jet compressor, said ratio being defined as that of the weight of propelling vapor to the weight of the vapor ejected and compressed by it. At a boiler pressure of 250 pounds per square inch the operative ratio of the jet compressor would be 20, while if the boiler pressure were 1000 pounds per square inch said operative ratio would only be 0.52. It will thus be clear that the efficiency of the present circuit is highest at high operating pressures therein, a preferred operating condition for the system being one in which the pressure at the boiler 5 would be between 500 and 1000 pounds per square inch absolute. Furthermore, with higher boiler pressures less heat is needed for vaporizing the propelling vapor, owing to the decrease of latent heat of vaporization with pressure. In determining the best boiler pressure it would obviously be necessary to operate at such a boiler pressure as will keep the boiler temperature well below the temperature of the heating fluid for the boiler. will be readily understood that provision of the pump '8 is essential in the present system.

Referring now to the composition of a reflux fluid which is produced in a refining plant of the type mentioned, a typical mixture would have It is noted that the above reflux mixture would have a range of boiling points of about 75 Fahrenheit degrees at atmospheric pressure, this In view of the foregoing, it

mixture having an initial boiling point of minus 50 degrees Fahrenheit and a final boiling point of. plus 25 degrees Fahrenheit. Said reflux mixture will operate very satisfactorily in the circuit of the present system, requiring only slight operation of the apparatus-and the peculiar type of refrigerant which may be used therein, certain means of automatic control are provided to insure .a proper performance of the operative cycle for which the present apparatus is designed. .Thus, in order to insure a satisfactory heatexchange in the evaporator 9, a separator 34 is provided for preventing the passage of gasified refrigerant into the evaporator chamber 24. provides a closed chamber 35 connected in the .pipe 21at the discharge side of the expansion valve 28, and further connected in the pipe 29 whereby the gasified refrigerant from the evaporator chamber 24 may flow through its upper portion. Since it is generally desirable that a predetermined level of liquid in the chamber 24 be maintained, a float control device 36 is provided in association with the separator 34,

said device operative to control the setting of the expansion valve 28 for maintaining the desired liquid level in the evaporator and separator. It will be understood that the separator 34 functions to remove any gasified refrigerant resulting from the liquid discharge through the valve 28 whereby only liquefied refrigerant is delivered to the evaporator f'or evaporation by means of the heat emanated from the fluid in the coil 25.

It is also desirable that the liquid refrigerant be maintained at a fixed level in the boiler 5, and to that end a by-pass pipe 31 is provided connecting the pipe 23 with the pipe I! whereby excess liquid refrigerant may be directly returned to the condenser 1. A normally closed valve 30 is interposed in the pipe 35 and said valve is arranged for control in accordance with the liquid level in the boiler through a float control device 39 which directly actuates the valve. In this manner, any tendency to an excessive liquid content in the boiler is automatically prevented.

A safety valve 4| is provided for the condenser. In the case where the refrigerant comprises a'mixture of compounds having differing boiling points, a pressure controlled valve 42 may also be provided in an outlet pipe for the condenser whereby to permit the escape of any gaseous ingredients of the mixture which may not be liquefied under aparticular operating condition of the apparatus. The valve 42 would, of course, open at a lower pressure than would the safety valve 4|.

Means are also provided for maintaining the desired flow ratio at the jet compressor, or ejector, 6. As particularly illustrated, means comprises the provision of a diaphragm motor valve 44 in the pipe 23 which delivers liquid refrigerant from the pump to the boiler 5, and is controlled in terms of the flow rates As particularly shown, the separator 34- said I of compressed air in its diaphragm chamber,

said air conveyed to the valve through a pipe 45 connected with a compressed air source ,(not shown). An air valve 46 is interposed in. the pipe 45, said valve being of a double diaphragm motor type and having valve-actuating diaphragms controlled by the differentials in pressure at opposite sides of orifice plates 41 and 48 interposed in the pipes l3 and 29 respectively. A constantly open needle valve 49 in the pipe 45, and at the discharge side of the valve 46, is operative to constantly relieve the pressure in the pipe 45 at an adjusted rate. -By using orifice plates to have equal pressure differences for the desired flow rates in the respective pipes, the fiow through the valve 46 may be held constant as long as a proper flow ratio obtains in the pipes I3 and 29.

Should the flow ratio change from its desired normal, the air flow through the valve 46 will be automatically varied to appropriately change the operative air pressure at the valve 44 for restoring said flow ratio to normal.

From the foregoing description taken in connection with the accompanying drawing, the advantages of the construction and method of operation will be readily understood by those skilled in the art to which the invention appertains, and whi e I have described the principle of operation, together with the device which I now consider to be the best embodiment thereof, I desire to have it understood that the device shown is merely illustrative, and that such changes may be made, when desired, as fall within the scope of the appended claims.

Having thus described my invention, I claim as new and desire to secure by Letters Patent of the United States the following:

1. In a continuously operable refrigeration circuit, a boiler, an ejector'receivinga stream of gasified refrigerant from said boiler, a condenser receiving the discharge from said ejector, a duct conducting condensate from said condenser back to said boiler, an evaporator comprising the cooling means of the circuit and directly receiving condensate from said condenser, means connecting said evaporator to said ejector whereby the latter is arranged to remove gasified refrigerant from said evaporator, and means automatically operable in said duct in accordance with the quantity flow rates of gasifled refrigerant from the boiler andevaporator to the ejector to maintain the ratio of said flow rates at a constant and predetermined value.

2. In a continuously operable refrigeration system, a boiler and an ejector and a condenser connected in a continuous closed circuit, said ejector receiving gasified refrigerant from said boiler, an evaporator comprising the cooling means of the system included in a branch circuit to receive liquefied refrigerant from the condenser and to deliver gasifled refrigerant to the ejector, and means operative in the connection between the condenser and boiler and in accordance with the flow rates of the streams to said ejector to automatically maintain a predetermined flow ratio between said streams.

3. In a continuously operable refrigeration system, a boiler and an ejector and a condenser connected in a continuous closed circuit, said ejector receiving gasified refrigerant from said boiler, an evaporator comprising the cooling means of the system and included in a branch circuit to receive liquefied refrigerant from the condenser and to deliver gasified refrigerant to the ejector, a motor valve controlling the flow of liquefied refrigerant from the condenser to the boiler, and means operative in joint accordance with the flow rates of the streams of gasified refrigerant to said ejector to automatically determine the setting of said motor valve.

4. In a continuously ,operable refrigeration system, a boiler and an ejector and a condenser connected in order in a closed circuit, said ejector receiving a propelling stream of gasified refrigerant from said boiler, means automatically operative to maintain constant temperature and pressure conditions in said propelling stream of control the ficw of liquefied refrigerant from the condenser to the boiler, and means simultaneously coactive in accordance with the flow conditions in the said streams to the ejector to control said valve for the maintaining a predetermined fiow ratio between said streams.

5. In a continuously operable refrigeration system, a boiler and an ejector and a condenser connected in a continuous closed circuit, said ejector receiving gasified refrigerant from said boiler, an evaporator comprising the cooling means of the system included in a branch circuit to receive liquefied refrigerant from the condenser and to deliver gasified refrigerant to the ejector, and valve means operative in a connection of the first circuit and in joint accordance with the flow rates of the streams to said ejector to automatically maintain a predetermined flow ratio between said streams.

6. In a continuously operable and closed refrigeration circuit, a boiler, an ejector, a duct conducting a propelling stream of gasified refrigerant from said boiler to the ejector, a condenser receiving the discharge from said ejector and connected with said boiler for supplying liquid refrigerant thereto, an evaporator comprising the cooling means of the circuit and directly receiving liquid refrigerant from said condenser, a duct connecting said evaporator to said ejector whereby the latter is operative to aspirate gasified refrigerant from said evaporator, back pressure valves independently operative in said ducts to automatically maintain predetermined and constant operating pressures in the boiler and evaporator, and means operative in a boiler connection of the circuit and in accordance with the flow rates of the streams in said ducts to automatically maintain a pre- 3 determined flow ratio between said streams whereby said ejector is arranged for operation as a jet compressor at a preferred said ratio for the refrigerant in the circuit.

FLOYD L. KALLAM.

gasified refrigerant, a motor valve operative to

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