CA2258462A1 - Modified heat exchanger - Google Patents
Modified heat exchanger Download PDFInfo
- Publication number
- CA2258462A1 CA2258462A1 CA 2258462 CA2258462A CA2258462A1 CA 2258462 A1 CA2258462 A1 CA 2258462A1 CA 2258462 CA2258462 CA 2258462 CA 2258462 A CA2258462 A CA 2258462A CA 2258462 A1 CA2258462 A1 CA 2258462A1
- Authority
- CA
- Canada
- Prior art keywords
- housing
- burner
- heat exchanger
- flame tube
- flame
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/18—Arrangement or mounting of grates or heating means
- F24H9/1809—Arrangement or mounting of grates or heating means for water heaters
- F24H9/1832—Arrangement or mounting of combustion heating means, e.g. grates or burners
- F24H9/1836—Arrangement or mounting of combustion heating means, e.g. grates or burners using fluid fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
- F23M9/00—Baffles or deflectors for air or combustion products; Flame shields
- F23M9/06—Baffles or deflectors for air or combustion products; Flame shields in fire-boxes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/0005—Details for water heaters
- F24H9/001—Guiding means
- F24H9/0026—Guiding means in combustion gas channels
- F24H9/0031—Guiding means in combustion gas channels with means for changing or adapting the path of the flue gas
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
There is described a new and improved heat exchanger of the sort having an external housing, a burner for providing heat to the housing, a seal to prevent the escape of combustion gases between the burner housing and the burner and a flame tube communicating with the burner to direct flame and hot gas into the housing, the improvement wherein the flame tube is removably connected to the housing to provide improved access to the housing's internal surfaces.
Description
MODIFIED HEAT EXCHANGER
FIELD OF THE INVENTION
The present invention relates to heat exchangers and more particularly to heat exchangers capable of being cleaned internally using high pressure fluid.
S BACKGROUND OF THE INVENTION
Fuel fired heat exchangers of the sort used for example to heat aircraft while on the ground must be fluid and gas tight to avoid the escape of toxic fumes and other combustion products into the air or other fluid flowing past the exchangers' outer surface and which is then used to heat the aircraft's interior. The exchangers have therefore been manufactured as completely sealed units that, even with the burner removed, are largely inaccessible for pressure washing of their internal surfaces. Deposits of soot, ash and carbon accumulate on these inner surfaces and will eventually diminish the exchanger's efficiency.
SUMMARY OF THE INVENTION
The applicant proposes to modify known heat exchangers to include a removable flame tube which, when removed, provides access to the exchanger's internal surfaces for cleaning using a pressure hose.
It is therefore an object of the present invention to provide a heat exchanger that obviates and mitigates from the disadvantages of the prior art.
It is a further object of the present invention to provide a heat exchanger that, while remaining a sealed unit, can nevertheless be internally accessed for pressure washing or other seance.
It is a further object of the present invention to provide a heat exchanger having a removable flame tube.
According to the present invention then, there is provided in a heat exchanger having an external housing, a burner for generating heat inside said housing, sealing means to provide fluid tight sealing between said burner and said housing and a flame tube communicating with said burner to direct flame and hot gases into said housing, the improvement wherein said flame tube is removably connected to said housing.
According to a further aspect of the present invention, there is also provided a heat S exchanger, comprising a fluid and pressure tight housing; burner means for producing heat in said housing; a flame tube for directing flame and hot gas from said burner means into said housing, wherein said flame tube is connected to said housing to be removable when access to said housing's interior is required; and sealing means disposed between said burner means and said housing to prevent the escape of combustion gases from said housing.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the present invention will now be described in greater detail, and will be better understood when read in conjunction with the following drawings in which:
Figure 1 is a cross-sectional, side-elevational view of a known heat exchanger;
Figure 2 is an end view of the heat exchanger of Figure 1;
Figure 3 is a cross-sectional side-elevational view of the heat exchanger of Figure 1 modified to include a removable flame tube;
Figure 4 is a side-elevational view of the removable flame tube;
Figure 5 is a cross-sectional side-elevational view of the heat exchanger of Figure 3 with the flame tube removed;
Figure 6 is a cross-sectional side-elevational view of the heat exchanger of Figure 3 with a burner attached; and Figure 7 is a side-elevational view of a blind gasket.
DETAILED DESCRIPTION
With reference to Figure 1, there is shown a known heat exchanger 1 of the type manufactured for example by Stewart-Warner Corporation.
The exchanger includes a generally cylindrical housing 10 having a peripherally extending outer surface 12 and two end walls or surfaces 14 and 15. End wall 14 is permanently connected such as by welding to outer surface 12 along edge 13 so that the connection is completely pressure and gas tight. End surface 15 is formed with a central aperture 18 (best seen in Figure 2), for permanent gas and pressure tight connection to a flame tube 20 that extends deep into the exchangers' flame room 22. An exhaust flue 25 is provided on surface 12. The purpose of the elongated flame tube, which is usually 30 to 45 cm in length, is to maintain a steady flame 29 in different firing conditions and to create as long a path as possible for the hot exhaust gases past the exchanger's outer surfaces 14 and 12 in the direction of arrows A before the cooled gases are lead away through exhaust flue 25. Figure 6 shows the heat exchanger with a fuel burning burner 35 attached. Sealing between the burner and end surface 15 around aperture 18 and flame tube 20 is provided by means of a gasket 36 compressively clamped between the burner and end surface 15 by a plurality of nut and bolt fasteners 37.
As will be appreciated, even with burner 35 removed, there is virtually no access to the exchanger's inner surfaces for cleaning way deposits 8 because of the permanent connection and length of flame tube 20.
One solution is to use a shorter flame tube but this would markedly shorten the path of the exhaust gases and diminish the exchanger's overall efficiency. In this regard, there would be less cooling of the exhaust gases due to heat exchange, and the temperature of the gas flowing through flue 25 would be considerably higher. Another possible solution is to cut hatches into outer surfaces 12 or 14 and provide sealable covers for the hatches. It is extremely difficult however to make the covers completely gas and pressure tight due to the repeated thermal expansions and contractions of surfaces 12 and 14 which can literally become red hot during the exchanger's operation. Gasket 36 between the burner and end wall 15 provides effective sealing, but this is largely due to the fact that end surface 15 is the exchanger's coldest surface and is therefore subject to the least amount of thermal expansion and contraction.
Taking advantage of surface 15's relative coolness, and with reference to Figures 3, 4, 5 and 6, the applicant proposes a modification to known heat exchangers to replace permanent flame tube 20 with a relatively short permanently affixed sleeve 38 and a removable flame tube 40 that fits concentrically through the sleeve.
More specifically, with reference to Figures 3 and 4, flame tube 40 remains a cylindrical tube of the required length but it is now a discrete and removable component. Tube includes an outwardly extending lip or flange 41 formed at one of its ends.
Lip 41 seats against a peripherally extending shoulder portion 39 formed at the permanent connection between a relatively short (up to approximately 10 cm) cylindrical sleeve 38 and aperture 18 in end wall 15. Providing a shoulder portion 39 in the sleeve allows lip 41 to be recessed into surface 15 so that it does not interfere with the compression fit between gasket 36 and end surface 15. However, lip 41 could just as easily bear against end surface 15 directly and the central opening in the gasket could simply be made a bit larger for clearance around the lip.
In all events, complete pressure and gas tight sealing is still provided by gasket 36 which remains positioned between the relatively cool burner and the exchanger's coolest combustion surface to completely surround and seal the non-gas tight connection between tube 40 and shoulder 39.
Other means of supporting and connecting a removable flame tube in the exchanger will occur to those skilled in the art without departing from the scope of the present invention.
For example, lip 41 could be connected to surface 14 using short metal screws.
To clean the exchanger's flame room 22, burner 35 is removed, followed by the removal of tube 40. This allows internal access for a pressure washer 50 as shown in Figure 5.
In the alternative to fitting a removable tube 40 into the exchanger, the tube can be permanently or semi-permanently attached to the burner itself.
In the embodiment shown in Figure 6, additional sealing can be provided by a gasket between lip 41 and gasket 36 or by means of O-rings, not shown, between tube 40 and the burner's nozzle 34.
Heat exchanger 1 is normally positioned within a plenum, not shown, through which air, or sometimes a liquid, is pumped to pass over the exchanger to be heated and then circulated to the space to be heated, such as an aircraft cabin. To improve the rate of heat exchange, outer surface 12 can be fluted, as shown in Figure 2, or finned in order to increase its surface area for maximum heat transfer. It is also possible to arrange tubes 60, shown in dotted lines in Figure 6, to cross the flame room to further increase heat transfer. These techniques and others for improving the exchanger's efficiency are known in the art.
For pressure testing the exchanger, burner 35 can be removed and a blind gasket 70 shown in Figure 7 can be attached over aperture 18. Pressure is then applied to the exchanger's interior.
FIELD OF THE INVENTION
The present invention relates to heat exchangers and more particularly to heat exchangers capable of being cleaned internally using high pressure fluid.
S BACKGROUND OF THE INVENTION
Fuel fired heat exchangers of the sort used for example to heat aircraft while on the ground must be fluid and gas tight to avoid the escape of toxic fumes and other combustion products into the air or other fluid flowing past the exchangers' outer surface and which is then used to heat the aircraft's interior. The exchangers have therefore been manufactured as completely sealed units that, even with the burner removed, are largely inaccessible for pressure washing of their internal surfaces. Deposits of soot, ash and carbon accumulate on these inner surfaces and will eventually diminish the exchanger's efficiency.
SUMMARY OF THE INVENTION
The applicant proposes to modify known heat exchangers to include a removable flame tube which, when removed, provides access to the exchanger's internal surfaces for cleaning using a pressure hose.
It is therefore an object of the present invention to provide a heat exchanger that obviates and mitigates from the disadvantages of the prior art.
It is a further object of the present invention to provide a heat exchanger that, while remaining a sealed unit, can nevertheless be internally accessed for pressure washing or other seance.
It is a further object of the present invention to provide a heat exchanger having a removable flame tube.
According to the present invention then, there is provided in a heat exchanger having an external housing, a burner for generating heat inside said housing, sealing means to provide fluid tight sealing between said burner and said housing and a flame tube communicating with said burner to direct flame and hot gases into said housing, the improvement wherein said flame tube is removably connected to said housing.
According to a further aspect of the present invention, there is also provided a heat S exchanger, comprising a fluid and pressure tight housing; burner means for producing heat in said housing; a flame tube for directing flame and hot gas from said burner means into said housing, wherein said flame tube is connected to said housing to be removable when access to said housing's interior is required; and sealing means disposed between said burner means and said housing to prevent the escape of combustion gases from said housing.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the present invention will now be described in greater detail, and will be better understood when read in conjunction with the following drawings in which:
Figure 1 is a cross-sectional, side-elevational view of a known heat exchanger;
Figure 2 is an end view of the heat exchanger of Figure 1;
Figure 3 is a cross-sectional side-elevational view of the heat exchanger of Figure 1 modified to include a removable flame tube;
Figure 4 is a side-elevational view of the removable flame tube;
Figure 5 is a cross-sectional side-elevational view of the heat exchanger of Figure 3 with the flame tube removed;
Figure 6 is a cross-sectional side-elevational view of the heat exchanger of Figure 3 with a burner attached; and Figure 7 is a side-elevational view of a blind gasket.
DETAILED DESCRIPTION
With reference to Figure 1, there is shown a known heat exchanger 1 of the type manufactured for example by Stewart-Warner Corporation.
The exchanger includes a generally cylindrical housing 10 having a peripherally extending outer surface 12 and two end walls or surfaces 14 and 15. End wall 14 is permanently connected such as by welding to outer surface 12 along edge 13 so that the connection is completely pressure and gas tight. End surface 15 is formed with a central aperture 18 (best seen in Figure 2), for permanent gas and pressure tight connection to a flame tube 20 that extends deep into the exchangers' flame room 22. An exhaust flue 25 is provided on surface 12. The purpose of the elongated flame tube, which is usually 30 to 45 cm in length, is to maintain a steady flame 29 in different firing conditions and to create as long a path as possible for the hot exhaust gases past the exchanger's outer surfaces 14 and 12 in the direction of arrows A before the cooled gases are lead away through exhaust flue 25. Figure 6 shows the heat exchanger with a fuel burning burner 35 attached. Sealing between the burner and end surface 15 around aperture 18 and flame tube 20 is provided by means of a gasket 36 compressively clamped between the burner and end surface 15 by a plurality of nut and bolt fasteners 37.
As will be appreciated, even with burner 35 removed, there is virtually no access to the exchanger's inner surfaces for cleaning way deposits 8 because of the permanent connection and length of flame tube 20.
One solution is to use a shorter flame tube but this would markedly shorten the path of the exhaust gases and diminish the exchanger's overall efficiency. In this regard, there would be less cooling of the exhaust gases due to heat exchange, and the temperature of the gas flowing through flue 25 would be considerably higher. Another possible solution is to cut hatches into outer surfaces 12 or 14 and provide sealable covers for the hatches. It is extremely difficult however to make the covers completely gas and pressure tight due to the repeated thermal expansions and contractions of surfaces 12 and 14 which can literally become red hot during the exchanger's operation. Gasket 36 between the burner and end wall 15 provides effective sealing, but this is largely due to the fact that end surface 15 is the exchanger's coldest surface and is therefore subject to the least amount of thermal expansion and contraction.
Taking advantage of surface 15's relative coolness, and with reference to Figures 3, 4, 5 and 6, the applicant proposes a modification to known heat exchangers to replace permanent flame tube 20 with a relatively short permanently affixed sleeve 38 and a removable flame tube 40 that fits concentrically through the sleeve.
More specifically, with reference to Figures 3 and 4, flame tube 40 remains a cylindrical tube of the required length but it is now a discrete and removable component. Tube includes an outwardly extending lip or flange 41 formed at one of its ends.
Lip 41 seats against a peripherally extending shoulder portion 39 formed at the permanent connection between a relatively short (up to approximately 10 cm) cylindrical sleeve 38 and aperture 18 in end wall 15. Providing a shoulder portion 39 in the sleeve allows lip 41 to be recessed into surface 15 so that it does not interfere with the compression fit between gasket 36 and end surface 15. However, lip 41 could just as easily bear against end surface 15 directly and the central opening in the gasket could simply be made a bit larger for clearance around the lip.
In all events, complete pressure and gas tight sealing is still provided by gasket 36 which remains positioned between the relatively cool burner and the exchanger's coolest combustion surface to completely surround and seal the non-gas tight connection between tube 40 and shoulder 39.
Other means of supporting and connecting a removable flame tube in the exchanger will occur to those skilled in the art without departing from the scope of the present invention.
For example, lip 41 could be connected to surface 14 using short metal screws.
To clean the exchanger's flame room 22, burner 35 is removed, followed by the removal of tube 40. This allows internal access for a pressure washer 50 as shown in Figure 5.
In the alternative to fitting a removable tube 40 into the exchanger, the tube can be permanently or semi-permanently attached to the burner itself.
In the embodiment shown in Figure 6, additional sealing can be provided by a gasket between lip 41 and gasket 36 or by means of O-rings, not shown, between tube 40 and the burner's nozzle 34.
Heat exchanger 1 is normally positioned within a plenum, not shown, through which air, or sometimes a liquid, is pumped to pass over the exchanger to be heated and then circulated to the space to be heated, such as an aircraft cabin. To improve the rate of heat exchange, outer surface 12 can be fluted, as shown in Figure 2, or finned in order to increase its surface area for maximum heat transfer. It is also possible to arrange tubes 60, shown in dotted lines in Figure 6, to cross the flame room to further increase heat transfer. These techniques and others for improving the exchanger's efficiency are known in the art.
For pressure testing the exchanger, burner 35 can be removed and a blind gasket 70 shown in Figure 7 can be attached over aperture 18. Pressure is then applied to the exchanger's interior.
As will be appreciated, the use of removable tube 40 continues to afford the same advantages of maximum heat transfer and coldest exhaust afforded by a similarly long but permanently installed flame tube, but by being removable, the exchanger's flame room can be easily and readily accessed by a pressure hose for removal of soot, dirt and other efficiency S robbing deposits. The exchanger as a whole however remains completely pressure and gas tight. There is therefore no safety comprise.
The above-described embodiments of the present invention are meant to be illustrative of preferred embodiments and are not intended to limit the scope of the present invention.
Various modifications, which would be readily apparent to one skilled in the art, are intended to be within the scope of the present invention. The only limitations to the scope of the present invention are set forth in the following claims appended hereto.
The above-described embodiments of the present invention are meant to be illustrative of preferred embodiments and are not intended to limit the scope of the present invention.
Various modifications, which would be readily apparent to one skilled in the art, are intended to be within the scope of the present invention. The only limitations to the scope of the present invention are set forth in the following claims appended hereto.
Claims (6)
1. In a heat exchanger having an external housing, a burner for generating heat inside said housing, sealing means to provide fluid tight sealing between said burner and said housing and a flame tube communicating with said burner to direct flame and hot gases into said housing, the improvement wherein said flame tube is removably connected to said housing.
2. The heat exchanger of claim 1 wherein said housing includes an aperture in a surface thereof for injection of flame from said burner into said housing, said aperture including a peripherally extending sleeve extending a short distance into said housing, said removable flame tube being received concentrically through said sleeve and into said housing.
3. The heat exchanger of claim 1 wherein said sleeve includes a peripherally extending shoulder portion and said removable flame tube includes a radially extending flange at an end thereof, said flange being adapted to abut said shoulder portion to position said removable tube relative to said housing.
4. The heat exchanger of claim 3 wherein said sealing means circumscribe said shoulder portion to provide fluid tight sealing for said removable flame tube.
5. The heat exchanger of claims 1, 2, 3 or 4 wherein upon removal of said removable flame tube, at least a major portion of the internal surfaces of said housing are accessible for cleaning and servicing.
6. A heat exchanger, comprising:
a fluid and pressure tight housing;
burner means for producing heat in said housing;
a flame tube for directing flame and hot gas from said burner means into said housing, wherein said flame tube is connected to said housing to be removable when access to said housing's interior is required; and sealing means disposed between said burner means and said housing to prevent the escape of combustion gases from said housing.
a fluid and pressure tight housing;
burner means for producing heat in said housing;
a flame tube for directing flame and hot gas from said burner means into said housing, wherein said flame tube is connected to said housing to be removable when access to said housing's interior is required; and sealing means disposed between said burner means and said housing to prevent the escape of combustion gases from said housing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2258462 CA2258462A1 (en) | 1999-01-13 | 1999-01-13 | Modified heat exchanger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2258462 CA2258462A1 (en) | 1999-01-13 | 1999-01-13 | Modified heat exchanger |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2258462A1 true CA2258462A1 (en) | 2000-07-13 |
Family
ID=29554953
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2258462 Abandoned CA2258462A1 (en) | 1999-01-13 | 1999-01-13 | Modified heat exchanger |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2258462A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20180216815A1 (en) * | 2017-01-27 | 2018-08-02 | Sermeta | Heat exchanger |
-
1999
- 1999-01-13 CA CA 2258462 patent/CA2258462A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20180216815A1 (en) * | 2017-01-27 | 2018-08-02 | Sermeta | Heat exchanger |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |