US2740588A - Method of and means for circulating a heat-transferring liquid in a closed system - Google Patents

Description

April 3, 1956 w. BENDER 2,740,588

METHOD OF AND MEANS FOR CIRCULATING A HEAT-TRANSFERRING LIQUID IN A CLOSED SYSTEM Filed March 1, 1952 I m emon' Wmu BEHDER METHOD F AND MEANS FOR CIRCULATING A HEAT-TRANSFERRING LIQUID IN vA CLOSED SYSTEM Willi Bender, Berlin, Germany, assignor to Pintsch Bamag Alttiengesellschaft Application March 1, 1952, Serial No. 274,465

Claims priority, application Germany March 9, 1951 9 Claims. (Cl. 237--56) The invention relates to a method of, and means for, circulating n heat-transferring liquid in a closed system.

With known methods and arrangements for heating apparatus for evaporating, distilling-and chemical reacting purposes by means of an organic heating medium, for example diphyl, which is a mixture ofdiphenyl oxide and diphenyl, flowing in a closed circuit, it has been found that the thermo-syphonic effect alone'is not sufiicient for a good heat transfer and that it is necessary to pump the heating medium around the closed circuit, the heating medium being evaporated and condensed in a closed heating-coil system known per se comprising, behind a heat-receiving portion of the heating-coil system, a separator which retains liquid particles and from which the liquid phase is returned by a duct to the heat-receiving portion while the steam phase flows through a duct to a heat-consuming apparatus, for example an autoclave, and from which the steam phase returns as condensate to the heat-receiving portion.

it is an object of the invention to-provide a method of, and means for, circulating a heat-transferring liquid in a closed system in which the circulation is inherently improved without the necessity of providing mechanical means, such as a pump.

Other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of an embodiment of the invention when read in conjunction with the accompanying drawing diagrammatically illustrating an embodiment of the invention.

The invention is based-on the idea ofadding one or more gases, for example hydrogen, helium, or nitrogen under pressure to the heating medium, for example diphyl, the pressure being chosen to correspond to'the desired temperature. The gaseous phase is partly dissolved by the liquid and is, on evaporation of the liquid, expelled again, whereby the circulation of the heat-transferring medium is enhanced. Moreover, the enhanced circulation is still further improved by the alteration of the volume of the gaseous phase in dependence on the temperature.

In the drawing, a heat receiving portion .1 (i. e. heat evolving means) of the heating-coil system is arranged in a combustion chamber, the organic heating medium being heated and vaporized in the heat-receiving portion 1. Thecombustion chamber is heated by a combustible gas or oil G While compressed air .1. is added. The mixture of liquid and steam reaches a separator 2 in .Which the liquid phase is separatedfrom the steam-gaseous phase. The liquid leaving the separator 2. flows through-aduct 3 back into the portion 1. The mixture of vapor and gas leaving the separator 2 flows through a duct 4 .into an apparatus 5 (i. e. heat evolving means)-to be heated, for example an autoclave, the heat of'whichis fed to :a substance to be heated. The condensate, he. the liquid consisting of condensed vapor plus gas dissolved therein, leaving the autoclave 5 is fed back through :a duct fi-into the heat-receiving portion 1.

To allow for the increase in volume of :the heating hired tates Patent medium, which is due to the raised temperature, a receiver 7 is inserted into the duct 6 for the-condensate. The action of gravity causes a circulation of the heating medium in the direction indicated by the arrows owing to the fact that in the falling duct the-condensate is collected until it reaches a certain level. In any case, this level 'lies above the uppermost winding of the coil of the heat-receiving portion 1, the circulation of the heating medium being additionally enhanced by the decrease in volume of the heating medium, which takes place in the autoclave due to the condensation of the fluid vapor, as well as by the decrease in volume of the gaseous phase due to dissolution of the gas in the fluid which now is in liquid state again and by the reduced pressure thus created in this part of thesystem. Thereby, the mixture of vapor and gas is sucked otf from the heat-receiving portion 1.

The receiver 7 (i. e. collecting means) consists of a helical tube; it has to be arranged as high as possible above the heat-receiving portion '1, but below the auto clave 5. By this arrangement, a high level of the condensate is obtained, which also enhances the circulation. Incidentally, the additional advantage is thereby obtained that the autoclave remains free of the condensate.

When the heated material has to be cooled as quickly as possible, then the duct 4 for the mixture of vapor and gashas to be short circuited to the duct 6 for the condensate by a connecting duct 8, which may be a cooled tube or else may be constructed as a cooling device. This short-circuiting duct 3 need not be provided with a valve, because the mixture of vapor and gas will always flow to that place at which a lower pressure exists. in order that the autoclave 5 remains in fact switched out of the circulation, it is necessary to ensure the condensation .in another portion of the circulation system, for example between the autoclave 5 and the heat-receiving portion 1, in which case the short-circuiting duct it has to be cooled. Instead of cooling the duct 8, alternatively the receiver '7 or else the duct ,6 for the condensate may be constructed as a cooling device.

For filling the circulation system, a storage container 9 is provided, at a higher level than that of the autoclave 5, the heating medium flowing under its own Weight from the storage container 9 towards the circulation system after valves 10 and .llhave been opened. During filling, a vent valve 12 has to be open so that the air in the circulation system can escape. The circulation system is filled with the heating medium until the latter reaches the vent valve 12, which is then closed. After the valve 11 has been also closed, the gaseous phase Wfor example hydrogen, helium, or nitrogenis added to the circulation system through a duct 13, whereby the liquid level andthe pressure can be adjusted in a desired manner, the excess heating medium being pressed back into the storage container 9. After .the filling of the circulation system has been completed, the valve 10 is closed and, for the required operation, the control valve 11 is opened fully or in part whereby to control the speed with which the heating medium circulates.

For emptying the circulation system, the valve 11 is closed, the valve 10 is opened and, by means of compressed air L fed through the duct 13, the heating medium is pressed back into the storage container 9. By this arrangement the loss of heating medium may be minimized. The storage container'9 is vented by means of a long tube 14 having a separator for the liquid and being arranged above the roof.

It should be clearly understood that the accompanying drawings are given by way of example only, many modifications, additions .and omissions being possible without departing from the'spirit of this invention.

I claim:

1. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; and a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid and a circulation accelerating low boiling point gas, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbing means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respeclively, which in turn causes acceleration of circulation of said heat transferring fluid.

2. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point or said circuit; and a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid and a circulation accelerating low boiling point gas, said gas being selected from the group consisting of hydrogen, helium, and nitrogen, said gas being insoluble in said hi h boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbing means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respectively, which in turn causes acceleration of circulation of said heat transferring fluid.

3. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid and a circulation accelerating low boiling point gas, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means; and storage means for said heat-transferring fluid connected to said conduit means between said heat evolving means and said heat absorbing means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbin means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means Where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respectively, which in turn causes acceleration of circulation of said heat transferring fluid.

4. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid and a circulation accelerating low boiling point gas, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heatevolving means; storage means for said heat-transferring fluid connected to said conduit means between said heat evolving means and said heat absorbing means and arranged on a level higher than said heat evolving means; and valve means for closing and opening the connection between said storage means and said conduit means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbing means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respectively, which in turn causes acceleration of circulation of said heat transferring fluid.

5. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid and a circulation accelerating low boiling point gas, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means; and means connected around said heat absorbing means for separating and removing liquid from said mixture leaving said heat absorbing means and for returning the liquid to the latter means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbing means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respectively, which in turn causes acceleration of circulation of said heat transferring fluid.

6. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid and a circulation accelerating low boiling point gas, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means; and collecting means in said conduit means between said heat evolving means and said heat absorbing means for receiving condensate of said heat transferring liquid from said heat evolving means and for returning the con densate to said heat absorbing means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat aba conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid and a circulation accelerating low boiling point gas, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means; storage means for said heat-transferring fluid connected to said conduit means between said heat evolving means and said heat absorbing means and arranged on a level higher than said heat evolving means; valve means for closing and opening the connection between said storage means and said conduit means; and collecting means in said conduit means between said heat evolving means and said heat absorbing means for receiving condensate of said heat transferring liquid from said heat evolving means and for returning the condensate to said heat absorbing means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbing means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respectively, which in turn causes acceleration of circulation of said heat transferring fluid.

8. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; and a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid consisting of diphenyl oxide and diphenyl, and a circulation accelerating low boiling point gas, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbing means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respectively, which in turn causes acceleration of circulation of said heat transferring fluid.

9. A heating apparatus comprising, in combination, a conduit means forming a closed circuit having vertically spaced lower and higher points; heat-absorbing means in said circuit at said lower point thereof; heat evolving means at said higher point of said circuit; and a mixture being under pressure and filling said conduit means and composed of a heat-transferring high boiling point fluid consisting of diphenyl oxide and diphenyl, and a circulation accelerating low boiling point gas, said gas being selected from the group consisting of hydrogen, helium, and nitrogen, said gas being insoluble in said high boiling point fluid at the pressure and temperature prevailing in said heat absorbing means and soluble in said fluid at the pressure and temperature prevailing in said heat-evolving means, said heat transferring fluid in liquid state and with said gas substantially dissolved therein being vaporized in said heat absorbing means whereby said gas is released, the thus created fluid vapor and gas mixture flowing into said heat evolving means where said fluid vapor is condensed and said gas again dissolved therein, said release and dissolution of said gas from and in said fluid resulting in increase of pressure in said heat absorbing means and reduction of pressure in said heat evolving means, respectively, which in turn causes acceleration of circulation of said heat transferring fluid.

References Cited in the file of this patent UNITED STATES PATENTS 1,087,274 Check et al Feb. 17, 1914 2,360,665 Fields Oct. 17, 1944 2,510,737 Buffington June 6, 1950 2,532,608 Dalin Dec. 5, 195.0

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