WO2004085931A2

WO2004085931A2 - A thermal fluid heater

Info

Publication number: WO2004085931A2
Application number: PCT/US2004/008240
Authority: WO
Inventors: Thomas M. Smith
Original assignee: Smith Thomas M
Priority date: 2003-03-19
Filing date: 2004-03-18
Publication date: 2004-10-07
Also published as: WO2004085931A3

Abstract

The invention is an improved thermal fluid heater (10) that is energy efficient and pollution free. The fluid is preferably preheated prior to entering the heating chamber with the recycled exhaust gas. By preheating the fluid prior to reaching the heater chamber thereby saves heating cost of the fluid. The thermal fluid heater preferably contains a U-shaped tube (40) or serpentine finned tubes (36) that permits a fluid to travel through it. The fluid then travels through at least one IR heater. (30). The temperature of the exiting fluid can be controlled and used as a heating source.

Description

A THERMAL FLUID HEATER RELATED APPLICATIONS

[0001] This application claims benefit to provisional application Serial No.

60/534,220, filed January 5, 2004 and provisional application Serial No. 60/455,983, filed March 19, 2003, which are incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION [0002] The invention is to develop a fluid heater that is energy efficient and pollution free. The fluid is preferably preheated with the exhaust gas prior to entering the heater chamber. By preheating the fluid prior to reaching the heater chamber thereby saves heating cost of the fluid.

SUMMARY OF THE INVENTION [0003] An object of the invention is to develop an improved thermal fluid heater that is energy efficient and pollution free. The fluid is preferably preheated prior to entering the heating chamber with the recycled exhaust gas. By preheating the fluid prior to reaching the heater chamber thereby saves heating cost of the fluid. [0004] The invention relates to a thermal fluid heater comprising a flat infrared

("TR") heat-exchanger having inner and outer surfaces through which a thermal fluid is passed, the outer faces of said IR heat-exchanger being coated with a high emissive coating to absorb a high portion of the incident thermal radiation emanating from the high efficiency, non-polluting, flat, gas-fired infrared emitters, which are positioned closely opposing each flat side of said LR heat-exchangers in order to rapidly, uniformly and efficiently heat the thermal fluid passing through the heat exchanger. [0005] The terms "pipe" and "tube" will be used interchangeably throughout the application. The term "flat" means substantially parallel to the ground surface within about +/- 5°. In other words, "flat" is 180° +/- about 5°. The term "thin" is about 0.5 to about 2 inches thick. The term "compound shaped" refers to any shape such as trapezoid, hexagonal, heptagonal, rhombus, or just abstract shapes not having particular defined signs.

[0006] BRIEF DESCRIPTION OF THE FIGURES

[0007] Figure 1 is a top plan view of the thermal fluid heater of this invention;

[0008] Figure 2 is a perspective view of the thermal fluid heater of this invention;

[0009] Figure 3 is a perspective view similar to Figure 2 with the front housing cover of the thermal fluid heater to illustrate air and gas inlet controls;

[00010] Figure 4 is a cross-sectional view in the elevation taken along the 4-4 line of Figure 3;

[00011] Figure 5 is a cross-sectional view in the elevation taken along the 5-5 line of Figure 3 similar to that of Figure 4 looking in the opposite direction;

[00012] Figure 6 is a cross-sectional perspective view in elevation taken along the line 6-6 of Figure 3;

[00013] Figure 7 is a top plan view of another embodiment of the thermal fluid heater of this invention;

[00014] Figure 8 is a cross-sectional view in elevation taken along line 8-8 of

Figure 7; and

[00015] Figure 9 is a cross-sectional view in elevation taken along line 9-9 of

Figure 7; [00016] Figure 10 is a front elevational view of still another embodiment of the thermal fluid heater of this invention;

[00017] Figure 11 is a fragmental cross-sectional plan view taken along line 11-1 1 of Figure 10;

[00018] Figure 12 is a fragmental front elevational view of one dimple assembly of this invention looking at the dimple in its longitudinal plane;

[00019] Figure 13 is a cross-sectional view in top plan view showing the abutting dimples and the flow passage way between the front and rear plates taken along line 13-

13 of Figure 12;

[00020] Figure 14 is a fragmental front elevational view of the dimple assembly of

Figure 12 oriented laterally to show the width of the weld slot; and

[00021] Figure 15 is a fragmental cross-sectional view in top plane of the front and rear plates welded together at the abutting dimples taken along line 15-15 of Figure 14;

[00022] Figure 16 is a side elevation view in cross section of another embodiment of the thermal fluid heater of this invention; and

[00023] Figure 17 is an end elevation view in cross section of the thermal fluid heater as shown in Figure 16.

DETAILED DESCRIPTION OF THE INVENTION [00024] Figure 1 illustrates the top plan view of a thermal fluid heater 10 of this invention. The thermal fluid heater 10 contains a housing 20, fluid inlet pipes 18, at least one fluid flow tube such as U-shaped tube 40 and at least one infrared heater 30. The term U shaped tube or pipe will be used throughout the application although the pipe or tube does not have to have be U shaped tube or pipe. The shape of the tube is preferably U shaped. The housing 20 covers and protects the thermal fluid heater 10. Any conventional housing can be used. It must be made of a material that can withstand the heat of the heater. The infrared ("TR") heaters 30 can be any conventional IR heater, such as but not limited to the LR heaters described in U.S. Patent Nos. 6,412,190; 6,190,162; 6,033,211, 5,464,346; 5,306,140; 5,090,898; 5,046,944; 5,024,596; 4,830,651; 4,722,681; 4,666,400; 4,654,000; 4,634,373; 4,604,054; 4,589,843; 4,500,283; 4,492,564; 4,474,552; 4,447,205; 4,443,185; 4,416,618; 4,378,207 and 4,224,018; which are incorporated herein in their entirety for all purposes by reference thereto. Preferably the IR heater has flanges such as shown in U.S. Patent No. 6,190,162.

[00025] Gas inlet line 80 and air inlet line 90 permit gas and air respectively to flow into gas/air mixture pipes 60. The gas inlet line 80 has two connector lines 85 that are connected to air inlet lines 90. The gas and air are mixed at this connection and then flow through gas/air mixture pipe 60 to fuel the TR heaters. These connector pipes 85 are each provided with inline on/off switches 100, pressure regulator valves 110 and solenoids 70 respectively. The on/off switches control the flow. The pressure regulator valve 110 controls the gas pressure of the lines 85 and the solenoid valve 70 regulates the flow of the gas. The gas pressure and flow through connector pipes 85 preferably are the same, but are independently adjustable if required.

[00026] Figure 2 illustrates the exhaust pipe 115 connected to the housing 20. The fluid enters in the pipe 120 that is connected through the exhaust pipe 115 to a venturi shaped manifold 125 that supplies the fluid to many U-shaped fluid flow pipes 126 that are spaced within U-shaped hot air exhaust pipes 40 (see Figure 4). The fluid travels through the U-shaped tubes 40 and passes through the IR heater 30 and leaves the thermal fluid heater through the manifold 130. There can be a housing control cover 25 that covers the inlet pipes, heaters, etc. as shown in Figure 2.

[00027] Figure 3 shows the perspective view similar to Figure 2 with the front housing cover 25 removed from the thermal fluid heater 10. The gas and air lines 80 and 90 are shown. The gas and air are mixed in the gas/air mixture pipes 60 which are fed to the TR heater 30. The amount of gas fed to the gas/air mixture pipes 60 are controlled by the solenoid valves 70. The solenoid valves 70 are used to regulate the flow of gas to the air inlet pipe 90. If the solenoid valve 70 is completely open there is complete flow of gas into the gas/air mixture pipes 60. If the solenoid valve is partially open then less gas is permitted in the gas/air mixture pipe 60. If the solenoid valve 70 is closed then no gas passes into the gas/air mixture pipe 60.

[00028] As shown in Figure 4, the fluid enters from the inlet pipes 120 into the manifold 125 to U-shaped fluid flow pipe 126 within the U-shaped exhaust pipe 40. The U-shaped pipes 126 can be made of any high temperature withstanding material. The U- shaped flow pipe 126 and exhaust pipe 40 form two chambers. The fluid enters the U- shaped flow pipe 126 in the center chamber. The outer exhaust pipe 40 can contain fins 50 between the outer exhaust pipe and the inner flow pipe as shown in Figures 1, 4, 5, 6. Alternating the spaced fins 50 is used to help channel the flow of the recycled gas or steam in order to preheat the fluid. The alternating spaced fins 50 are arranged so that close off 180° of the space between outer exhaust pipe 40 and inner flow pipe 126. The recycled steam or gas moves in a serpentine path through the U-shaped exhaust pipe 40 in the outer chamber around the fluid in the inner chamber flow pipe 126 prior to the fluid entering the IR heaters 30. This raises the temperature of the fluid prior to the fluid being submitted to the heating cycle in the heaters thereby reducing the amount of energy necessary for heating the fluid.

[00029] At least one LR heater 30 is heating the U-shaped flow pipe 126 as shown in Figures 1, 4, 5 and 6. The fluid flows down the U-shaped pipe 126 and then travels upward towards the TR heaters 30. Again, the exhaust gas flows in a serpentine path through the fins 50 to the exhaust box 140. The fluid is preheated before it reaches the main TR heater 30. In Figure 4, there is shown four stacked opposing pairs of IR heaters 30 through the U-shaped pipes 126.

[00030] Figure 5 illustrates a cross-sectional view in the elevation taken along line

5-5 of Figure 3 similar to Figure 4 looking in the opposite direction. In order to increase the efficiency of the heater 10 insulation 150 can be added that goes around the U-shaped exhaust pipe 40. The insulation 150 prevents heat escaping from the U-shaped exhaust pipe 40 and the fluid.

[00031] Figure 6 illustrates the inlet fluid coming into the inlet manifold 125 which direct the fluid into pipes 126. The fluid would travel down in the center chamber of the U-shaped pipe 126 while being heated by the recycled gas traveling through the outer chamber of the U-shaped exhaust pipe 40. As stated above the recycled gas can travel through outer channel that contains the fins 50. After the fluid has been preheated by the gas, the fluid than travels to the IR heaters 30. There is at least one ER heater 30 and there are four opposing pairs of IR heaters shown in figure 6. The temperature of the exiting fluid can be controlled and used as a heating source. [00032] The superheated fluid in pipes 126 exit through the venturi fluid manifold

130 to supply fluid to water heaters, thermal base heaters and hygiene sterilizers at hospitals. This heater also has the possibility of producing steam heat.

[00033] Figure 7 illustrates the top plan view of a thermal fluid heater 10A of this invention.

[00034] As shown in Figures 7-9 the thermal fluid heater consist of a housing 20A.

Within the upper part of the housing 20A are a pair of opposing Gas ("LR") infrared heaters 30A with a flat plate IR heat exchanger 32 disposed between them.

[00035] Below the flat plate IR heat exchanger 32 is a shell 35 and tube 36 type convection heat exchanger 34. The shell 35 is an insulation material.

[00036] The heat exchanger 34 is arranged in a serpentine pattern of finned tubes

36 to carry the heated fluid to the TR heat exchanger 32 to be explained in greater detail later in the specification.

[00037] Improvements are using ZERO NO x and ZERO CO emitting gas through lines 38 to the gas (IR) heaters 30A and the flat plate IR absorbing heat exchanger 32 is coated with high emissivity coating such as, but not limited to 840-M manufactured by

Aremco Products Inc., Valley Cottage, NY 10989. The demand fluid heater has a power modulation range of 4.5 to 1, reaches full radiant output in less than 5 seconds has a thermal efficiency of better than 92% and is packaged in a case measuring approximately

48" high by 29" wide by 72" long less the combustion air and exhaust fans (not shown).

[00038] The convection shell and tube heat exchanger 34 has a longitudinal top opening 41 to receive the hot exhaust gases from the gas TR heaters 30 A. These exhaust gases are directed in a rectangular, clockwise fashion along the finned water filled tubes for the maximum preheat transfer. Cold water pipe 42 enters the housing 20A and is connected through the finned tubes and the water is preheated on its way to the flat plate TR heat exchanger via inlet pipe 44. The IR heat exchanger has internal baffles 46 that direct the preheated water to flow in an essentially vertical serpentine path for maximum turbulence and surface area contact of the fluid.

[00039] The gap 48, between the alternating baffles from the top wall and the bottom wall of the heat exchanger 30 A, is approximately 0.25 inches. This gap besides causing turbulance of the fluid also serves to purge air from the exchanger upon startup. [00040] The total heat system is designed as a counter flow type exchanger to utilize the upper high power density TR to finish heating the water and the lower power density hot water heater to initiate the preheating water process. The super heated water exits from the housing via line 51.

[00041] Figures 10 and 11 illustrate a front elevational view and a longitudinal cross sectional view respectively of another thermal heater design 32 A. [00042] This design consists of a flat front plate 152 and rear flat plate 154 that are closed at the top and bottom. The plates 152 and 154 are spaced apart as shown by the dimension "A" in Figure 13. The dimension "A" is preferably approximately 1/8 inch. The plates 152 and 154 are spaced by a series of abutting elongated dimples 156 and 158 projecting inward from plates 152 and 154. The plates 152 and 154 are preferably spaced equally apart. The dimples 156 and 158 all have the same oval shape and size, except the front dimple 156 has an extra centrally disposed slot 160 as shown in Figures 12-15. This slot 160 allows quick registered spot welding of the plates together. [00043] The heated fluid enters the thermal heater 32A through attached inlet pipe

44 A and pressure equalizing manifold 162 on the right side of the heater. The fluid flow in a direct path as shown by the rows 163 through the "A" passageway which is preferably about 1/8 of an inch and the super heated fluid exits the left side of the heater via a pressure equalizing manifold and recovery pipe 51 A to a heating unit not shown.

[00044] It has been found that the longitudinal aligned welded dimples within the

1/8 inch passageway forms flow paths with only slight eddy currents, permitting higher fluid pressures with the same velocity of flow and improved heat transfer all of which occurs within a very narrow heater width.

[00045] Figure 16 illustrates the top plan view of a thermal fluid heater 10B of this invention.

[00046] As shown in Figures 16 and 17 the thermal fluid heater comprises a housing 20A. Within the upper part of the housing 20A are a pair of opposing Gas ("ER") infrared heaters 30A with a flat plate TR heat exchanger 32 disposed between them.

[00047] Below the flat plate IR heat exchanger 32 is a shell 35 and tube 36 type convection heat exchanger 34. The shell 35 is an insulation material.

[00048] The heat exchanger 34 is arranged in a serpentine pattern of finned tubes

[00049] As described above, improvements are using ZERO NO x and ZERO CO emitting gas through lines 38 to the gas (ER) heaters 30A and the flat plate IR absorbing heat exchanger 32 is coated with high emissivity coating such as, but not limited to 840-

M manufactured by Aremco Products Inc., Valley Cottage, NY 10989 or HEM 2000 made by Energymax Inc. HEM 2000 is a high emissivity coating for the outside of process tubes. Emissivity 0.96+. Service to 2000F/1 lOOC.

[00050] The demand fluid heater has a power modulation range of 4.5 to 1, reaches full radiant output in less than 5 seconds has a thermal efficiency of better than 92% and is packaged in a case measuring approximately 48" high by 29" wide by 72" long less the combustion air and exhaust fans (not shown).

[00051] The convection shell and tube heat exchanger 34 has a longitudinal top opening 41 to receive the hot exhaust gases from the gas ER heaters 30 A. These exhaust gases are directed in a rectangular, clockwise fashion along the finned water filled tubes for the maximum preheat transfer. Cold water pipe 42 enters the housing 20A and is connected through the finned tubes and the water is preheated on its way to the flat plate

ER heat exchanger via inlet pipe 44. The ER heat exchanger has internal baffles 46 that direct the preheated water to flow in an essentially vertical seφentine path for maximum turbulence and surface area contact of the fluid.

[00052] The gap 48, between the alternating baffles from the top wall and the bottom wall of the heat exchanger 30A, is approximately 0.25 inches. This gap besides causing turbulance of the fluid also serves to purge air from the exchanger upon startup.

[00053] The total heat system is designed as a counter flow type exchanger to utilize the upper high power density ER to finish heating the water and the lower power density hot water heater to initiate the preheating water process. The super heated water exits from the housing via line 51.

[00054] The thermal fluid heater has many applications where auxiliary water heating is needed at commercial, industrial and institutional facility. [00055] All the patents described above are incoφorated by reference in their entirety, for all useful puφoses including all the drawings.

[00056] While there is shown and described certain specific structures embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described.

[00057] GLOSSARY OF REFERENCE CHARACTERS

10- thermal fluid heater

10 A - thermal fluid heater

10B - thermal fluid heater

18- fluid inlet pipe

20- housing

20A- housing

25- housing control cover

30- infrared/thermal radiation heater

30A - gas infrared heaters

32 - flat plate R heat exchanger

32A - thermal heater design

34 - shell and tube type heat exchanger

35 - shell

36 - finned tubes 38 - line - fluid flow tubes (U-shaped tubes) - longitudinal top opening - cold water pipe - inlet pipe A - inlet pipe - internal baffles - gaps - fins - line A -recovery pipe - gas/mixture pipe - solenoid valve - gas line pipe - connector lines - air line pipe 0- on/off valve 0- regulator valve 5- exhaust pipe 0- pipe 5- venturi-shaped manifold 6- flow pipe 0 - manifold 0 -exhaust box 150 -insulation 152 - flat front plate 154 -rear flat plate 156 - dimples 158 -dimples 160 -slot

162 -manifold

163 - rows

Claims

I Claim:

1 A thermal fluid heater comprising a flat infrared ("ER") heat-exchanger having inner and outer surfaces through which a thermal fluid is passed, the outer faces of said IR heat-exchanger being coated with a high emissive coating to absorb a high portion of the incident thermal radiation emanating from the high efficiency, non-polluting, flat, gas-fired infrared emitters, which are positioned closely opposing each flat side of said IR heat-exchangers in order to rapidly, uniformly and efficiently heat the thermal fluid passing through the heat exchanger.

2. The thermal fluid heater as claimed in claim 1, wherein said ER heat-exchanger and said flat infrared emitters are square, rectangular, circular or compound shaped.

3. The thermal fluid heater as claimed in claim 1, wherein said heat-exchanger is a flat heat-exchanger having tapered in-flow and tapered out-flow manifolds to insure uniform cross flow of the thermal fluid.

4. The thermal fluid heater as claimed in claim 1, comprising a flat ER heat- exchanger, irradiated by opposing gas-fired infrared emitters, having a finned tube secondary convection/conduction heat-exchanger to absorb the thermal energy remaining in the combustion gases exhausted by the infrared emitters.

5. The thermal fluid heater as claimed in claim 1, further comprising a speed controlled combustion air fan supplying combustion air at a super atmospheric pressure to a venturi mixing valve which intern supplies the premix gas/air to the infrared emitters, said combustion air fan speed is controlled to maintain a pre-se "t temperature of the exiting thermal fluid within design flow limits and a exhaust fan producing a negative atmospheric pressure in the chamber surrounding the heat exchangers, said exhaust fan being speed controlled to maintain a relative negative atmospheric pressure surrounding the heat exchangers during modulation of the infrared emitters' intensity.

6. The thermal fluid heater as claimed in claim 1, wherein gas-fired infrared emitters utilizing a high emmisivity fibrous ceramic composite emitter face that operates with the initial combustion zone embedded about 3 mm within the infrared emitter's outer face greatly improving both the conversion to radiation efficiency and the combustion efficiency of the infrared emitter and reducing the production of NOx and CO so that they are non-detectable at 1 ppm discrimination.

7. The thermal fluid heater as claimed in claim 1, wherein the thermal fluid is water.

8. The thermal fluid heater as claimed in claim 1, wherein the thermal fluid has a maximum operating temperature of 700 degrees F.

9. The thermal fluid heater as claimed in claim 1, wherein the infrared emitter's back-side operates at a temperature below 120 degrees F. eliminating the need for back-side thermal insulation and permitting a very compact design.

10. Trie thermal fluid heater as claimed in claim 1, wherein the ER heat-exchanger is constructed of two .06 +/- thick titanium plates welded together in a leak-proof manner with fluid flow paths that minimize fluid pressure drop and provide adequate fluid turbulance to reduce fluid film temperatures.