US3365133A

US3365133A - Heat powered portable fluid heaters

Info

Publication number: US3365133A
Application number: US516641A
Authority: US
Inventors: John P Norton; Harold L Kirk
Original assignee: American Air Filter Co Inc
Current assignee: MILL AND MINE SERVICES Inc A CORP OF; American Air Filter Co Inc
Priority date: 1965-12-27
Filing date: 1965-12-27
Publication date: 1968-01-23
Anticipated expiration: 1985-01-23
Also published as: DE1579636A1

Description

Jan. 23, 1968 J. P. NORTON ETAL 3,365,133

HEAT POWERED PORTABLE FLUID HEATERS Filed Dec. 27, 1965 2 Sheets-Sheet 1 I c I 4 /36 I Q F /6 /4 I fl r 35 3 ll 23 39/ 25 -39 /H Ll 27 INVENTORS Jan. 23, 1968 J. P. NORTON ETAL 3,365,133,

HEAT POWERED PORTABLE FLUID HEATERS Filed Dec. 27, 1965 2 SheetsSheet 2 I NVENTORS United States Patent 3,365,133 HEAT FOWERED PGRTABLE FLUID HEATERS John P. Norton, St. Louis, and Harold L. Kirk, Kirirwood, Mo, assignors to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Filed Dec. 27, 1965, Ser. No. 516,641 7 Claims. (Cl. 237-7) ABSTRAT OF THE DISCLQSURE A self-contained heat powered fluid heater having a motive fluid circulating system where the motive fluid is heated to drive a rotary engine to provide power for the apparatus and heat is transferred from the motive fluid to the fluid to be heated. A bypass means is provided to bypass a portion of the motive fluid around the engine in response to the condition of the motive fluid.

Background of the invention Some previous portable fluid heaters have included means, usually a burner, for heating the fluid as desired, and a separate power supply for auxiliary equipment which usually includes a means for moving the fluid to be heated through the heater, a blower for supplying combustion air to the burner, and a fuel pump to supply fuel to the burner. In most previous portable fluid heaters the separate power supply has been an internal combustion engine or an electric motor, both of which have certain inherent disadvantages when used in such portable heaters.

Other previous heat-powered fluid heaters have not required a separate source of power for the auxiliary equipment because the power has been furnished by a gas turbinedriven by exhaust gas from the fluid heating means, usually a burner. In these previous heaters, the auxiliary equipment has usually included blowers for moving the fluid to be heated, and a fuel pump to supply fuel to the burner. In such previous gas turbine-powered, fluid heaters it has also been necessary to provide an air compressor to furnish compressed combustion air to the burner upstream of the turbine. The compressors in such previous heat-powered fluid heaters which have been driven by the turbine are necessarily complex and consume a significant amount of the power generated by the burner. In addition to wasting a great deal of power in compressing combustion air, such heaters are ineflicient because a significant portion of the work done in compressing combustion air is lost when the hot, compressed combustion gases are exhausted from the heat exchange system. The air compressor also requires an increase in the size and complexity of the turbine required to furnish power to auxiliary equipment. The over-all fuel efliciency of such heaters is dependent on the efliciency of the turbine because it is required to operate the air compressor. Also, in previous heaters where exhaust gas has been used to drive the turbine, the exhaust gas contains the products of combustion from the burner, is therefore corrosive, andcomplicates design of the turbine.

The present invention provides an eflicient and novel portable heat-powered fluid heater wherein a single motive fluid can be heated to provide a source of power for auxiliary equipment, and to provide heating medium to the heat exchange system. Moreover, the new and advantageous heater of the present invention eliminates the previously required power consuming combustion air compressor and permits the use of a straightforward, fluid responsive engine wherein work expended to compress combustion air is not lost by exhausting the compressed combustion air from a heat exchanger to the atmosphere.

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Furthermore, etflciency of the fluid-responsive engine of the present invention is not a significant factor in determining the fuel efficiency of the heater because the motive fluid exhausted from the engine through a heat exchanger is not rejected, but is recycled within the system to prevent loss of heat to the atmosphere.

Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth hereinafter.

In accordance with the present invention, an improved, heat-powered, portable fluid heater arrangement is provided to heat a desired fluid comprising a motive fluid circulating system having a motive fluid supply source; a heat source within said system to expand the motive fluid including a motive fluid inlet and a motive fluid outlet; a fluid-flow responsive rotary engine in the system to provide powerto selected elements in the fluid circulating systern in response to passage of said motive fluid through the engine, the fluid flow responsive engine including a fluid inlet communicating with the boiler outlet to receive motive fluid from the boiler, and a motive fluid outlet to exhaust motive fluid from the engine; power output means cooperatively joined to the engine to transmit useful power resulting from the motive fluid passing through the engine to provide power as desired for the heater; heat exchange means in the system to transfer heat from the motive fluid to the fluid to be heated, including a first inlet to receive motive fluid communicating with the motive fluid outlet of the engine, to receive motive fluid, a first fluid outlet to exhaust motive fluid from the heat exchange means, a second inlet to receive fluid to be heated and a second outlet to emit the fluid which is heated; and motive fluid return means in the system including a motive fluid inlet communicating with the first heat exchanger outlet and a motive fluid outlet communicating with the boiler to return motive fluid from the heat exchanger to the boiler.

It is to be understood that various changes can be made by one skilled in the art in the arrangement, form and construction of the heater assembly disclosed herein 'without departing from the scope or spirit of the present invention.

Referring now to the drawings which show one advantageous embodiment of the present invention:

FIGURE 1 shows a schematic view of a heat-powered portable heater in accordance with the present invention;

FIGURE 2 is a vieW taken along a line passing through plane 2-2 of FIGURE 1;

FIGURE 3 is a View partly in section taken along a line passing through plane 33 of FIGURE 1; and

FIGURE 4 is a schematic view of one apparatus for furnishing fuel-air mixture to a burner in accordance With the present invention.

FIGURE 1 is an example of a portable heater in accordance with the present invention and includes a heat source in the form of an expanded motive fluid generator 3, a fluid-responsive engine 4 driven by pressurized motive fluid, a heat exchanger 11 to receive hot motive fluid and transfer heat from such motive fluid to a second fluid to be heated, and a power transmitting device 10 driven by fluid-responsive engine 4.

In the example of FIGURE 1, the fluid to be heated can, advantageously, be air which can be drawn from any desired source, heated by passing over heat exchanger 11, and blown into a space to be heated by fan 33 of the portable heat-powered heater of FIGURE 1.

Motive fluid generator 3 includes a heat source which, for purposes of the present example, can be a burner 17. In one example of the present invention the motive fluid can be vaporized as it is expanded and burner 17 can be cooperatively associated with boiler 1 to transfer the heat of combustion generated in burner 17 to motive fluid in boiler 1. Exhaust gases from burner 17 can be exhausted in any desired manner including blowing the exhaust gases into the space served by the heater; or into additional heat exchange means (not shown) to indircctly reclaim heat from such exhaust gases. In Example 1, an exhaust stack 22 can be provided to exhaust combustion gases to a desired remote location. Boiler 1 is in cooperative heat-receiving relation with burner 17 and can contain any suitable motive fluid which can be vaporized by the heat transferred from burner 1'7 It will be understood that a suitable motive fluid, for example a fluorocarbon, can, advantageously, be vaporiza'ble within a selected temperature range dependent upon the desired operating ranges of the heater of the present invention, but, advantageously, should not be easily degradable within the range of operation.

Vaporized motive fluid can be emitted from boiler 1 by means of conduit 2 at a rate dependent on the quantity of heat transferred to boiler 1 and the pressure maintained in conduit 2. Flow control valve 20 can be provided in conduit 2 to control rate of flow of vaporized motive fluid to fluid-responsive engine 4 and can be responsive to motive fluid pressure in conduit 2 by means of sensing element 20'.

It will be understood that, within the scope of the present invention, any suitable rotary fluid-responsive engine can be used; however, for purposes of the present example, engine 4 can be a turbine. Turbine 4 can receive vaporized motive fluid from boiler 1 and transform a portion of the pressure energy of the motive fluid to rotary motion by means of shaft 9 connected to turbine 4 with the pressure of the motive fluid being reduced.

Reduced pressure motive fluid is exhausted from turbine 4 through conduit 8 and the speed of rotation of turbine 4 can be controlled by controlling the pressure differential of the motive fluid across turbine 4 as measured from inlet 5 to conduit 36 which directly communicates with turbine outlet 8 and is downstream of bypass system 6. Bypass system 6 advantageously can be provided to pass pressurized motive fluid around turbine 4 at a selected rate. The portion of the motive fluid which is bypassed around turbine 4, and the portion of the motive fluid which passes through turbine 4, are combined in conduit 36 and passed to heat exchanger 11. Flow of pressurized motive fluid through bypass 6 can be controlled by means of valve 7 responsive through element 7 to motive fluid pressure in conduit 36 at the outlet of turbine 4.

Valves

20 and 7 can be cooperatively associated to control the pressure differential of motive fluid across turbine 4 and, therefore, the speed of rotation of turbine 4 and shaft 7. Turbine 4 of the portable heater of the present invention can be designed to furnish the maximum power requirements of the auxiliary equipment necessary for the operation of the heater of the present invention, and can, advantageously, also be designed to furnish additional useful power if desired.

As hereinbefore discussed, the pressure of the motive fluid is reduced in passing through turbine 4 and the converted energy translated to rotational energy of shaft 9. Shaft 9 can be adapted to furnish power directly to auxiliary elements of the present invention or alternatively can be connected to power transmitting device 10 to transfer rotational energy to auxiliary elements of the fluid circulating system of the portable heater of the present invention. It will be understood that within the scope of the present invention, power transmitting device 10 can be of any suitable arrangement or configuration to receive power, as from turbine 4, and transmit useful power at selected desired speeds. It will be further understood that power transmitting means 10 can include means (not shown) for selectively changing or controlling the speed transmitted to each of the elements of the fluid circulating system. For purposes of this example, power transmitting device 16 can be a gear train connected to turbine 4 by shaft 9 and including several means for transmitting power at different desired speed to the different elements of the heater.

In accordance with the present invention, the motive fluid exhausted from turbine 4 can be used to provide heat to the air to be heated and the motive fluid can be returned from heat exchanger 11 to boiler 1 without significant loss of heat to the atmosphere so the efliciency of turbine 4 is not a major factor in determining the fuel efficiency of the system.

Heat exchanger 11 can, advantageously, be designed to heat any desired fluid, but in the example of FIGURE 1, heat exchanger 11 can be designed to receive air. In heat exchanger 11, air is heated, motive fluid is cooled, and a portion of the motive fluid can be condensed as heat is removed. Condensed motive fluid rejected from heat exchanger 11 is collected in catch tank 12. While any suitable means may be employed to return condensed motive fluid to boiler 1, condensed motive fluid collected in catch tank 12 can be drawn by pump 14 through conduit 13, and returned to boiler 1 through conduit 16. Shaft 15 connected to power transmitting device 10 can be used to drive motive fluid pump 14 at desired speed to return condensed motive fluid to boiler 11.

It is to be understood that, in accordance with the present invention, any convenient means may be used to move fluid to be heated through the heater. In the example of FIGURE 1, shaft 34, driven by power transmitting device 10, can drive fan 33 to move air to be heated through duct 32 and over heat exchanger 11. In passing air over heat exchanger 11, the air is heated by heat removed from the motive fluid and a portion of the motive fluid can be condensed as hereinbefore described. Within the scope of the present invention, it will be understood that the air to be heated can include air which has been recirculated from the space served by the heater, fresh air, or a combination. FIGURE 3 indicates that heater 11 can include several motive fluid passes. It is to be understood, however, that within the scope of the present invention heat exchanger 11 can be of any desired configuration to receive motive fluid exhausted by turbine 4, or bypassed around turbine 4, and effectively transfer heat from the motive fluid to air to :be heated.

In the example of the present invention, as shown in FIGURE 1, combustion air can be furnished to burner 17 by blower 18 which can be driven at selected speed by shaft 21 connected to a power output from power transmitting device 10. Fresh combustion air can be provided to blower 18 by means of a convenient duct 19 which communicates with a suitable source of air.

Within the scope of the present invention, any suitable fuel such as kerosene can be used in the heater and any suitable means can be provided to supply fuel to burner 17. In one example of a means for providing fuel to burner 17 within the scope of the present invention, as shown in FIGURE 1, shaft 28 driven at selected speed from power transmitting device 10 can be provided to drive fuel pump 27. Fuel pump 27 can draw fuel from fuel storage tank 31 by means of conduit 29 to pump fuel to burner 17 through conduit 23. Valve 24 can be provided in fuel line 23 to regulate flow of fuel to burner 17, and therefore, the heat generated by burner 17 to be transferred to boiler 1. Valve 24 can regulate the flow of fuel to burner 17 in response to the temperature of air which has been heated by heat exchanger 11, where the temperature can be sensed by thermal bulb 26. Alternatively, valve 24 can regulate the flow of fuel to burner 17 in response to the temperature of motive fluid leaving heat exchanger 11, the temperature or pressure of vaporized motive fluid leaving boiler 1, or in response to any other suitable condition.

In accordance with the present invention, FIGURE 4 is an example of still another means for providing fuel to burner 17 which eliminates the mechanical fuel pump. Air from blower 18 driven by shaft 21 connected to power transmitting means can be directed through aspirator 41. Aspirator 41 includes dip tube 42 which extends below the surface of fuel 44 in tank 43. Air can be directed through aspirator 41, so fuel is drawn through tube 42 into aspirator 41 to form a combustible fuel-air mixture in intake line 46. Intake line 46 can communicate with burner 17 to provide the fuel-air mixture to burner 17 to provide heat of combustion to boiler 1 as hereinbefore described. Also, it will be understood that within the scope of the present invention, any suitable means can be provided to furnish fuel to burner 17, including, but not limited to, a compressed gaseous fuel wherein the fuel can be expanded into burner 17.

It will be understood that the method of operation of a heat-powered portable heater, within the scope of the present invention, will be determined by the particular configuration and combination of elements of the fluid circulating system. An example of a method of operation can be described for the apparatus in accordance with the present invention as shown in FIGURE 1.

In the example of FIGURE 1, burner 17 can be ignited to begin heating motive fluid in boiler 1. Fuel and combustion air can be furnished to burner 1 by manual mechanisms such as, for example, a hand-operated blower or manual operationof vapor-responsive engine 4, or by any other convenient means. In one example of the present invention, as shown in FIGURE 1, a hand-operated crank 47 can be provided to furnish the initial start-up power to power transmitting device 10 and thereby to any of the auxiliary elements of the fluid circulating sys tem of Example 1. Valves and 7 can, advantageously, be closed in response to low pressure in conduit 2 and turbine discharge line 36, respectively, during the startup of the heater. When the motive fluid in boiler 1 has been heated to a tempertaure corresponding to a preselected pressure in conduit 2, valve 20 opens to admit vaporized motive fluid to drive turbine 4. As flow of vaporized motive fluid increases, turbine 4 provides motive power to elements of the fluid circulating system of the example of FIGURE 1, and the furnishing of manual power is no longer required. Also, as the flow of vaporized motive fluid to turbine 4 increases, the discharge pressure of the turbine normally increases if the power requirements imposed on turbine 4 remain essentially constant. If the turbine discharge pressure increases in excess of a preselected minimum, valve 7 and bypass 6 open to allow vaporized motive fluid to pass around turbine 4 to reduce the pressure drop experienced by motive fluid passing through turbine 4. The rotational speed of turbine 4 advantageously is controlled by controlling the pressure drop of motive fluid in the system across turbine 4 in the manner hereinbefore described where the speed of rotation of turbine 4 varies directly with the pressure dilferential in the system across turbine 4. In operation of the fluid circulating system of this example and in accordance with the present invention, turbine 4 can receive a controlled quantity of motive fluid necessary for the operation of turbine 4 at a desired speed to meet the demands of a specific system. The remainder of vaporized motive fluid from boiler 1 can pass around turbine 4 to give up heat in heat exchanger 11 to the fluid to be heated.

Motive fluid condensed in heat exchanger 11 can be collected in tank 12. When a quantity of condensed motive fluid has been collected, motive fluid circulating pump 14 can be started to return motive fluid to boiler 1. Valve 39 in recirculating bypass 38 is closed unless the pressure in conduit 13 reaches a preselected minimum, when valve 39 opens to permit motive fluid to flow back into conduit 13. Low pressure in conduit 13 can result from several conditions including the presence of vaporized motive fluid in conduit 13. Recycling liquid motive fluid through bypass 38 to the inlet of pump 14 can facilitate pumping vaporized motive fluid back to boiler 1 and maintain the flow of motive fluid through the system.

The invention claimed is:

1. An improved heat powered, portable fluid heater apparatus comprising: a motive fluid circulating system having a motive fluid supply source; a heat source within said system to expand said motive fluid, said heat source including a motive fluid inlet and a motive fluid outlet; a fluid flow responsive rotary engine in said system to provide useful power in response to passage of said motive fluid through said engine, said engine including a fluid inlet communicating with said motive fluid outlet from said heat source, and a motive fluid outlet to exhaust motive fluid from said engine; bypass motive fluid conduit means having one end communicating with said motive fluid inlet of said engine and the other end communicating with said motive fluid outlet of said engine to bypass a portion of said motive fluid around said engine; motive fluid flow control means responsive to condition of motive fluid to control flow of motive fluid through said bypass motive fluid conduit means; power output means cooperatively joined to said engine to transmit useful power resulting from said motive fluid passing through said engine; heat exchange means in said system including first inlet communicating with said motive fluid outlet of said engine to receive motive fluid exhausted from said engine, and a motive fluid outlet from said heat exchange means to exhaust motive fluid from said heat exchange means; means to pass fluid to be heated through said heat exchange means in heat transfer relation; and, motive fluid return means including a motive fluid inlet communicating with said motive fluid outlet of said heat exchange means and a motive fluid outlet communicating with said heat source to return motive fluid from said heat exchanger to said heat source.

2. The apparatus of claim 1 wherein said motive fluid return means includes a pump driven by said power output means.

3. The apparatus of claim 1 including fluid pump means adapted to be driven by said power output means to pass fluid to be heated through said heat exchanger in heat transfer relation.

4. The apparatus of claim 1 wherein said heat source includes: a burner means having fuel and combustion air inlet means and an exhaust outlet means; and a boiler disposed to receive heat from said burner to vaporize said motive fluid, said boiler being disposed intermediate said inlet and said outlet.

5. The apparatus of claim 4 including air supply means adapted to be driven by said power output means, to furnish combustion air to said burner, said air supply means including an air inlet and an air outlet; and burner fuel supply pump means driven by said power output means to furnish fuel to said burner including fuel inlet means communicating with a source of fuel and outlet means communicating with said fuel inlet of said burner.

6. The apparatus of claim 4 including fuel-combustion air supply means comprising: air supply means adapted to be driven by said power output means to furnish combustion air to said burner, said air supply means including air inlet means and air outlet means; and fuel aspirator means including an air inlet communicating with said air outlet of said air supply means, said fuel aspirator means further including an outlet communicating with said burner fuel and said burner combustion air inlet means wherein said fuel aspirator means is adapted to draw fuel into said aspirator in response to flow of said combustion air through said aspirator means and mix said fuel and said combustion air in said aspirator means.

7. An improved, heat powered, portable air heater apparatus comprising: a motive fluid circulating system; a boiler in said system to vaporize a motive fluid including a motive fluid inlet and a vaporized motive fluid outlet; a burner in said system including fuel inlet means and combustion air inlet means and an exhaust outlet means, said burner being cooperatively disposed to transfer heat of combustion to said boiler to vaporize said motive fluid; a rotary fluid flow engine in said system to furnish useful power in response to flow of said motive fluid therethrough, said engine including a fluid inlet communicating With said boiler motive fluid outlet to receive motive fluid from said boiler, a motive fluid outlet to exhaust motive fluid therefrom, and power output means to transmit useful power of said engine to selected elements of said fluid circulating system; bypass motive fluid conduit means having one end communicating with said motive fluid inlet of said engine, the other end communicating With said motive fluid outlet of said engine to bypass a portion of said motive fluid around said engine and motive fluid control means to control flow of motive fluid through said bypass means in accordance with difference in motive fluid pressure between said inlet and outlet of said engine; combustion air blower means adapted to be driven by said power output means of said engine to furnish combustion air to said burner, said air blower means including air inlet means communicating with a source of combustion air and combustion air outlet means communicating with said combustion air inlet of said burner; a burner fuel pump adapted to be driven by said power output means to furnish fuel to said burner including fuel inlet means communicating with a source of burner fuel and a fuel out let means communicating with said fuel inlet of said burner; heat exchange means to transfer heat from said motive fluid to air to be heated including a first fluid inlet communicating with said motive fluid outlet of said engine to receive motive fluid, a first fluid outlet to exhaust motive fluid from said heat exchange means and means to pass a fluid to be heated over said heat exchange means in heat exchange relation; and a motive fluid return pump, to return motive fluid to said boiler from said heat exchanger, said pump adapted to be driven by said power output means and including an iniet cornmunicating with said outlet of said heat exchange means and an outlet communicating with said motive fluid inlet in said boiler.

References Cited UNITED STATES PATENTS 886,079 4/ 1908 Scollard 23712.1 995,154 6/1911 Kitchen 23712.1 1,047,622 12/1912 Donnelly 23'79 1,349,877 8/1920 Do'ble. 1,376,326 11/1921 Evans 237-121 1,476,201 12/1923 Haas. 2,217,610 10/ 1940 Shannon 23 625 X EDWARD 1. MICHAEL, Primary Examiner.