US20100288209A1 - heat exchanger for a boiler - Google Patents
heat exchanger for a boiler Download PDFInfo
- Publication number
- US20100288209A1 US20100288209A1 US12/756,381 US75638110A US2010288209A1 US 20100288209 A1 US20100288209 A1 US 20100288209A1 US 75638110 A US75638110 A US 75638110A US 2010288209 A1 US2010288209 A1 US 2010288209A1
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- Prior art keywords
- central chamber
- section
- heat exchanger
- flues
- fin
- 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
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
- F28D7/163—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing
- F28D7/1669—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing the conduit assemblies having an annular shape; the conduits being assembled around a central distribution tube
- F28D7/1676—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing the conduit assemblies having an annular shape; the conduits being assembled around a central distribution tube with particular pattern of flow of the heat exchange media, e.g. change of flow direction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D53/00—Making other particular articles
- B21D53/02—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers
- B21D53/04—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers of sheet metal
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- 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
- F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
- F24H1/22—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating
- F24H1/24—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers
- F24H1/26—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers the water mantle forming an integral body
- F24H1/28—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers the water mantle forming an integral body including one or more furnace or fire tubes
- F24H1/285—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers the water mantle forming an integral body including one or more furnace or fire tubes with the fire tubes arranged alongside the combustion chamber
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D9/0025—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being formed by zig-zag bend plates
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
- F28F9/22—Arrangements for directing heat-exchange media into successive compartments, e.g. arrangements of guide plates
- F28F2009/222—Particular guide plates, baffles or deflectors, e.g. having particular orientation relative to an elongated casing or conduit
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F2215/00—Fins
- F28F2215/06—Hollow fins; fins with internal circuits
Definitions
- the present invention relates to boilers and, in particular, to a heat exchanger for a boiler.
- Boilers are well known in the art and have numerous applications. For example, boilers may be used to provide hot water and heating for domestic or industrial use. Boilers may also be used to provide steam for use in process applications or locomotion of ships, trains, and other vehicles.
- the heat exchanger comprises a central chamber for receiving a combustion gas.
- a baffle divides the central chamber into a first section and a second section. The baffle also restricts the combustion gas from flowing directly from the first section of the central chamber to the second section of the central chamber.
- FIG. 1 is a perspective view of a first embodiment of an improved heat exchanger disposed within a boiler housing;
- FIG. 2 is a perspective view of the heat exchanger of FIG. 1 ;
- FIG. 3 is a section view taken along lines A-A of FIG. 2 ;
- FIG. 4 is a perspective view of a section of a blank used to form the central chamber, flues and fins of the heat exchanger FIG. 1 ;
- FIG. 5 is a front elevation view of the blank of FIG. 4 ;
- FIG. 6 is a sectional view taken along lines B-B of FIG. 3 ;
- FIG. 7 is a fragmentary, perspective view of a flue and fin of the heat exchanger of FIG. 1 ;
- FIG. 8 is an elevation view of the flue and fin of FIG. 7 ;
- FIG. 9 is a sectional view taken along line C-C of the flue channel of FIG. 8 showing a flue and fin as they would appear disposed therein;
- FIG. 10 is a sectional view taken along line D-D of the flue channel of FIG. 8 showing a flue and fin as they would appear disposed therein;
- FIG. 11 is a sectional view taken along line E-E of the flue channel of FIG. 8 showing a flue and fin as they would appear disposed therein;
- FIG. 12 is a perspective view of a second embodiment of an improved heat exchanger
- FIG. 13 is a perspective view of a section of a stamped steel strip used to form the central chamber, flues and fins of the heat exchanger of FIG. 12 ;
- FIG. 14 is a perspective view of a first side of a section of a blank used to form the central chamber, flues, and fins of the heat exchanger of FIG. 12 ;
- FIG. 15 is a perspective view of a second side of a section of a blank used to form the flues and fins of the heat exchanger of FIG. 12 ;
- FIG. 16 is a section view taken along lines F-F of FIG. 12 showing the outside of the heat exchanger
- FIG. 17 is another section view taken along lines F-F of FIG. 12 showing the inside of the heat exchanger.
- FIG. 1 this shows a first embodiment of an improved heat exchanger 10 disposed within a boiler housing 11 .
- the heat exchanger 10 comprises a central cylindrical chamber 12 .
- the central chamber 12 is divided into two sections 16 and 18 by a baffle 20 which is best shown in FIG. 3 .
- a plurality of flues for example, flues 22 a and 22 b are spaced-apart about a periphery of the central chamber 12 .
- Each of the flues 22 a and 22 b is in communication with both the first and second sections 16 and 18 of the central chamber 12 via a corresponding fin 24 a and 24 b, respectively.
- each of the flues is provided with a cap or fitting 23 and 25 at each end thereof.
- the fittings 23 and 25 close off ends of the flue 22 a.
- the caps or fittings 23 and 25 together with boiler housing 11 allow the heat exchanger 10 to be used in elevated pressure service, for example, domestic hot water supply at up to 150 psig.
- each of the flues is also provides with a divider stay 21 which is generally co-planar with the baffle 20 .
- flue gases from a combustion chamber enter the first section 16 of the central chamber 12 as indicated generally by arrow 100 .
- the baffle 20 prevents the flue gases from flowing directly from the first section 16 of the central chamber 12 into the second section 18 of the central chamber 12 . Instead the combustion gases must flow radially outward from the first section 16 of the central chamber 12 , through the fins 24 a and 24 b, and into the flues 22 a and 22 b.
- the divider stays 21 prevents the combustion gases from flowing downward along the fins 24 a and 24 b . Accordingly, the combustion gases are shunted along the flues 22 a and 22 b, past the baffle 20 , as indicated generally by arrow 102 .
- the flue gases flow radially inward from the flues 22 a and 22 b, through the fins 24 a and 24 b, and into the second section 18 of the central chamber 12 .
- the combustion gases flow out of the second section 18 of the central chamber 12 as indicated generally by arrow 104 . This will be described in greater detail below.
- the central chamber 12 , the flues 22 a and 22 b, and the fins 24 a and 24 b have a unitary structure.
- a single blank 28 which is shown in FIGS. 4 and 5 , may be used to form the central chamber 12 , the flues 22 a and 22 b, and the fins 24 a and 24 b.
- the blank 28 in this example, is a corrugated stainless steel blank having alternating crests 30 and troughs 32 . The ends of each of the troughs 32 are provided with a round 33 .
- a wall 34 extends between adjacent crests 30 and troughs 32 .
- the crests 30 have generally planar apexes 31 and will form an inner wall 13 of the central chamber 12 which is shown in FIGS. 2 and 3 .
- the grooves 32 have a generally rounded shape and will form the flues 22 a and 22 b which are shown in FIGS. 2 and 3 .
- the walls 34 extending between adjacent crests 30 and troughs 32 will define the fins 24 a and 24 b which are shown in FIGS. 2 and 3 .
- the blank 28 is formed into a desired structure, shown in FIG. 3 , by applying clamps (not shown) about the rounded troughs 32 .
- the clamps engage the walls 34 to form the fins 24 a and 24 b which allow communication between the central chamber 12 and flues 22 a and 22 b.
- FIG. 6 is a sectional view taken across line B-B of FIG. 3 .
- an inner wall 34 each fin is provided with a plurality of channel stays 36 and 38 .
- the channel stays 36 and 38 are spaced-apart and extend the length of the inner wall 34 of the fin 24 a.
- the channel stays 36 and 38 are button-like function to maintain opposed inner walls of the fin 24 a spaced-apart. This is best shown in FIG. 7 by slot-like openings 40 and 42 in the fin 24 a.
- the openings 40 and 42 are on opposite sides of a divider stay 21 .
- the channel stays 36 on a first side of the divider stay 21 differ in size from the channel stays 38 on a second side of the divider stay 21 .
- the channel stays may be graduated in size from one end of the inner wall 34 of the fin 24 a to the other. This will result in a longitudinally graduated spacing between the inner walls of the fin which may be desirable in some applications. Longitudinally graduated spacing accounts for the fact that the hot flue gases contract volumetrically as they cool, thus, requiring narrower channels as they progress though the heat exchanger.
- FIGS. 9 to 11 are sectional views taken along lines C-C, D-D, and E-E of FIG. 8 .
- FIG. 9 shows a portion 46 of the fin 24 a extending radially from the first section 16 of the central chamber 12 .
- the width W 1 of the opening 40 in the fin 24 a is sufficient to allow the combustion gases to readily flow from the first section 16 of the central chamber 12 , through the fin 24 a, and into the flue 22 a.
- FIG. 10 shows a portion 48 of the fin 24 a aligned with baffle 20 . In this situation the inner walls 34 and 35 of the fin 24 a abut to prevent flue gases from flowing around baffle 20 through the fin 24 . Flue gases from the first section 16 of the central chamber must therefore flow along the flue 22 a to bypass the baffle 20 .
- FIG. 10 shows a portion 46 of the fin 24 a extending radially from the first section 16 of the central chamber 12 .
- the width W 1 of the opening 40 in the fin 24 a is sufficient to allow the combustion gases to readily flow from the first section 16 of the central chamber 12 , through the fin 24 a, and
- FIG 11 shows a portion 50 of the fin 24 a as it appears when extending radially from the second section 18 of the central chamber 12 .
- the width W 2 of the opening when the fin 24 a extends radially from the second section of the central chamber 12 is less than the width W 1 of the fin 24 a when it extends radially from the first section 16 of the central chamber 12 .
- This is desirable because it increases the surface area of the heat exchanger 10 which is in contact with the combustion gases.
- this difference in the width of the openings 40 and 42 in the fin 24 a on opposite sides of the baffle 20 provides for a graduated decline in combustion gas temperature with a more even distribution of heat transfer.
- the lower temperature quench rate also reduces accretions of impurities in the combustion gases on heat transfer surfaces, and spreads out those which do occur. This results in reduced sensitivity to flue blockages and cleaning requirements.
- a mill certified coil strip of stainless steel having a fixed width is used to construct the heat exchanger 10 .
- the width of the strip will determine the height of the heat exchanger 10 .
- the strip first is uncoiled allowing it to be stamped and folded to produce the blank 28 shown in FIGS. 4 and 5 .
- the blank 28 is brought around and the side ends are welded together to form the central chamber 12 of the heat exchanger 10 shown in FIG. 2 .
- This design allows for scaling since the diameter of the heat exchanger 10 is dependent on the length of the strip used.
- a plurality of blanks may be welded together to form the heat exchanger 10 .
- the height of heat exchangers formed from the same coil strip of stainless steel will be constant.
- the stainless steel strip first passes through an in-line annealer to remove any work hardening induced through the manufacturing or coiling and uncoiling processes. From the annealer the strip is incrementally advanced through a stamping press that forms all the intricate features of the heat exchanger 10 . All the turbulating and pressure reinforcing features of the heat exchanger 10 are formed in the blank 28 at this stage because tooling has easy access to the strip in flat form.
- a die in the stamping press consists of two half sections and, in particular, a left half section for stamping a first blank and a right half section for stamping an adjacent blank. This allows a seam that connects adjacent blanks to occur on the outside of the folded blank making it easier to weld.
- a second stamping process cuts rounds 33 into the sections of the blank 28 that form the ends of the flues 22 a and 22 b.
- the rounds 33 allow edges of the blank 28 to meet for butt welding as will be discussed below.
- the next step involves forming the stamped sections of the strip into a fan like structure to form the blank 28 shown in FIG. 4 .
- the rounds 33 are drawn in to form the caps or fittings 23 and 25 found at each end of the flues 22 a and 22 b as shown in FIG. 2 .
- These two steps may be separated to allow for simpler tooling. It may also be desirable to incorporate an intermediate step to anneal the rounds to minimize the force required to form the caps or fittings 23 and 25 and reduce spring back.
- the blank 28 is cut to a desired length based on the desired diameter of the heat exchanger 10 being constructed.
- the blank 28 is subject to cleaning and passivation prior to applying clamps (not shown) to form the flues 22 a and 22 b, and the fins 24 a and 24 b. Removal of any tooling debris, lubricants, and dirt is important for consistent welding and corrosion resistance. It is desirable to clean and passivate the blank 28 prior to forming the flues and fins. Once the flues and fins are formed they are largely inaccessible for further tooling.
- the last step involves clamping the blank to the point that the opposing faces of corresponding ones the divider stays 21 and channel stays 36 and 38 meet.
- the side edges of the blank 28 are rounded about the baffle 20 and welded together. Spring back from the removal of the clamps is relieved by localized annealing of the flue channels 22 a and 22 b while the heat exchanger 10 is still clamped.
- the complete heat exchanger 10 is encased in a cylindrical boiler housing having ends with means to allow for the induction and exhaustion of combustion gases and ancillary sensor mountings.
- the heat exchanger 10 is disposed with a boiler housing (not shown) which contains a fluid being heated.
- the fluid is water which pumped to flow in a direction opposite the direction in which the combustion gases flow through the heat exchanger 10 .
- Combustion gases from a combustion chamber (not shown) flow into the first section 16 of the central chamber 12 as indicated by arrow 100 in FIG. 2 .
- the baffle 20 prevents the combustion gases from flowing directly from the first section 16 of the central chamber 12 into the second section 18 of the central chamber 12 . Instead the combustion gases must flow radially outward from the first section 16 of the central chamber 12 , via the fins 24 a and 24 b, and into the corresponding flues 22 a and 22 b.
- the combustion gases then flow along the flues 22 a and 22 b, past the baffle 20 , as indicated by arrow 102 in FIG. 2 .
- This increases a surface area of the heat exchanger 10 on which heat may be transferred from the flue gases in the flues 22 a and 22 b to the water being heated.
- the pressure in flues will increase. This, in turn, will result in combustion gases flowing from the flues 22 a and 22 b into the second section 18 of the central chamber 12 .
- the combustion gases then flow out of the second section 18 of the central chamber 12 as indicated generally by arrow 104 in FIG. 2 .
- the heat exchanger 10 offers the advantage that the central chamber 12 , flues 22 a and 22 b, and fins 24 a and 24 b of the heat exchanger 10 may be formed from a single blank 28 shown in FIGS. 4 and 5 . This may result in a decrease in manufacturing costs, particularly in costs associated with the assembly of the boiler, because of the reduced for welding and/or riveting.
- FIG. 12 this shows a second embodiment of an improved heat exchanger 110 .
- like parts have been given like reference numerals as in
- the heat exchanger 110 shown in FIG. 12 is generally similar to the heat exchanger shown in FIG. 2 with the exception that the second embodiment of the heat exchanger 110 is provided with a plurality of divider stays 121 a and 121 b which extend radial from the first section 116 of the central chamber 112 . As shown for a first one of the fins 124 a, the second embodiment of the heat exchanger 110 is also provided with a plurality of protrusions 127 a and 127 b stamped into the fins. The divider stays and protrusions are best shown in FIGS. 12 to 17 .
- a lowermost one of the divider stays 121 b is generally co-planar with the baffle 120 . Having a plurality of divider stays 121 a and 121 b above the baffle 120 keeps the flow of combustion gases laminar and the pressure drop low. Combustion gases have the highest volumetric and linear flow rate in the first section 116 of the heat exchanger 110 . Combustion gases also have the highest temperature and provide the highest heat flux in first section 116 of the heat exchanger 110 . Maintaining laminar flow helps reduce heat flux and prevent overloading of the fluid being heated.
- the protrusions 127 a and 127 b protrude inwardly from the inner wall 134 of the fins as best shown in FIG. 17 .
- the protrusions 127 a and 127 b function as turbulators. By the time the flue gases pass the baffle 120 they will have cooled significantly and heat flux will be considerably lower.
- the turbulators enhance heat flux.
- the turbulators features help disperse any condensate allowing the flue gases direct contact with the surface of the heat exchanger 110 .
Abstract
A heat exchanger for a boiler comprises a central chamber for receiving a combustion gas. A baffle divides the central chamber into a first section and a second section. The baffle also restricts the combustion gas from flowing directly from the first section of the central chamber to the second section of the central chamber. There is a plurality of spaced-apart flues disposed about a periphery of the central chamber. The flues allow for communication between the first section of the central chamber and the second section of the central chamber, in particular, the flues allow for combustion gas to flow from the first section of the central chamber to the second sections of the central chamber.
Description
- This application claims the benefit of provisional application 61/167,797 filed in the United States Patent and Trademark Office on Apr. 8, 2009, the disclosure of which is incorporated herein by reference and priority to which is claimed.
- 1. Field of the Invention
- The present invention relates to boilers and, in particular, to a heat exchanger for a boiler.
- 2. Description of the Related Art
- Boilers are well known in the art and have numerous applications. For example, boilers may be used to provide hot water and heating for domestic or industrial use. Boilers may also be used to provide steam for use in process applications or locomotion of ships, trains, and other vehicles.
- In fire-tube boilers, flue gases are channelled through flues surrounded by a fluid being heated. The boiler housing is a pressure vessel and contains the fluid which is typically water. Preferably numerous flues are provided to maximize the surface area on which heat may be transferred from the flue gases in the flues to the water being heated. U.S. Pat. No. 4,271,789 issued on Jun. 9, 1981 to Black discloses a boiler in which a plurality of flues extend from a combustion chamber into a boiler housing.
- However, in the prior art, the use of numerous flues or fluid carrying tubes increases the number of component parts in the boiler. This may result in increased manufacturing costs, particularly costs associated with the assembly of the boiler, because of the increased need for welding and/or riveting. There is accordingly a need for an improved heat exchanger for a boiler.
- It is an object of the present invention to provide an improved heat exchanger for a boiler.
- In particular, it is an object of the present invention to provide a heat exchanger which has sufficient surface area to efficiently heat a fluid in a boiler and is formed, at least in part, from a single blank to reduce welding requirements and thereby reduce metallurgical disturbances. It is also an object of the present invention to provide a heat exchanger that is in full ASME Section IV design conformity.
- There is accordingly provided an improved heat exchanger for a boiler. In one embodiment, the heat exchanger comprises a central chamber for receiving a combustion gas. A baffle divides the central chamber into a first section and a second section. The baffle also restricts the combustion gas from flowing directly from the first section of the central chamber to the second section of the central chamber. There is a plurality of spaced-apart flues disposed about a periphery of the central chamber. The flues allow for communication between the first section of the central chamber and the second section of the central chamber, in particular, the flues allow for combustion gas to flow from the first section of the central chamber to the second sections of the central chamber.
- The invention will be more readily understood from the following description of an embodiment thereof given, by way of example only, with reference to the accompanying drawings, in which:
-
FIG. 1 is a perspective view of a first embodiment of an improved heat exchanger disposed within a boiler housing; -
FIG. 2 is a perspective view of the heat exchanger ofFIG. 1 ; -
FIG. 3 is a section view taken along lines A-A ofFIG. 2 ; -
FIG. 4 is a perspective view of a section of a blank used to form the central chamber, flues and fins of the heat exchangerFIG. 1 ; -
FIG. 5 is a front elevation view of the blank ofFIG. 4 ; -
FIG. 6 is a sectional view taken along lines B-B ofFIG. 3 ; -
FIG. 7 is a fragmentary, perspective view of a flue and fin of the heat exchanger ofFIG. 1 ; -
FIG. 8 is an elevation view of the flue and fin ofFIG. 7 ; -
FIG. 9 is a sectional view taken along line C-C of the flue channel ofFIG. 8 showing a flue and fin as they would appear disposed therein; -
FIG. 10 is a sectional view taken along line D-D of the flue channel ofFIG. 8 showing a flue and fin as they would appear disposed therein; -
FIG. 11 is a sectional view taken along line E-E of the flue channel ofFIG. 8 showing a flue and fin as they would appear disposed therein; -
FIG. 12 is a perspective view of a second embodiment of an improved heat exchanger; -
FIG. 13 is a perspective view of a section of a stamped steel strip used to form the central chamber, flues and fins of the heat exchanger ofFIG. 12 ; -
FIG. 14 is a perspective view of a first side of a section of a blank used to form the central chamber, flues, and fins of the heat exchanger ofFIG. 12 ; -
FIG. 15 is a perspective view of a second side of a section of a blank used to form the flues and fins of the heat exchanger ofFIG. 12 ; -
FIG. 16 is a section view taken along lines F-F ofFIG. 12 showing the outside of the heat exchanger; -
FIG. 17 is another section view taken along lines F-F ofFIG. 12 showing the inside of the heat exchanger. - Referring to the drawings and first to
FIG. 1 , this shows a first embodiment of an improvedheat exchanger 10 disposed within aboiler housing 11. As best shown inFIG. 2 , theheat exchanger 10 comprises a centralcylindrical chamber 12. Thecentral chamber 12 is divided into twosections baffle 20 which is best shown inFIG. 3 . Referring back toFIG. 2 , a plurality of flues, for example,flues central chamber 12. Each of theflues second sections central chamber 12 via acorresponding fin flues 22 a, each of the flues is provided with a cap or fitting 23 and 25 at each end thereof. Thefittings flue 22 a. The caps orfittings boiler housing 11 allow theheat exchanger 10 to be used in elevated pressure service, for example, domestic hot water supply at up to 150 psig. As further shown, for the first one of theflues 22 a, each of the flues is also provides with adivider stay 21 which is generally co-planar with thebaffle 20. - In this example, flue gases from a combustion chamber (not shown) enter the
first section 16 of thecentral chamber 12 as indicated generally byarrow 100. Thebaffle 20 prevents the flue gases from flowing directly from thefirst section 16 of thecentral chamber 12 into thesecond section 18 of thecentral chamber 12. Instead the combustion gases must flow radially outward from thefirst section 16 of thecentral chamber 12, through thefins flues fins flues baffle 20, as indicated generally byarrow 102. After passing thebaffle 20 the flue gases flow radially inward from theflues fins second section 18 of thecentral chamber 12. The combustion gases flow out of thesecond section 18 of thecentral chamber 12 as indicated generally byarrow 104. This will be described in greater detail below. - In this example and as best shown in
FIG. 3 , thecentral chamber 12, theflues fins FIGS. 4 and 5 , may be used to form thecentral chamber 12, theflues fins crests 30 andtroughs 32. The ends of each of thetroughs 32 are provided with around 33. Awall 34 extends betweenadjacent crests 30 andtroughs 32. There are a plurality ofstays walls 34. Thecrests 30 have generallyplanar apexes 31 and will form aninner wall 13 of thecentral chamber 12 which is shown inFIGS. 2 and 3 . Thegrooves 32 have a generally rounded shape and will form theflues FIGS. 2 and 3 . Thewalls 34 extending betweenadjacent crests 30 andtroughs 32 will define thefins FIGS. 2 and 3 . - Referring back to
FIGS. 4 and 5 , the blank 28 is formed into a desired structure, shown inFIG. 3 , by applying clamps (not shown) about the roundedtroughs 32. The clamps engage thewalls 34 to form thefins central chamber 12 andflues -
FIG. 6 is a sectional view taken across line B-B ofFIG. 3 . As shown for a first one of thefins 24 a, aninner wall 34 each fin is provided with a plurality of channel stays 36 and 38. The channel stays 36 and 38 are spaced-apart and extend the length of theinner wall 34 of thefin 24 a. The channel stays 36 and 38 are button-like function to maintain opposed inner walls of thefin 24 a spaced-apart. This is best shown inFIG. 7 by slot-like openings fin 24 a. Theopenings divider stay 21. In this example, the channel stays 36 on a first side of the divider stay 21 differ in size from the channel stays 38 on a second side of thedivider stay 21. This allows thespacings baffle 20. In other examples, the channel stays may be graduated in size from one end of theinner wall 34 of thefin 24 a to the other. This will result in a longitudinally graduated spacing between the inner walls of the fin which may be desirable in some applications. Longitudinally graduated spacing accounts for the fact that the hot flue gases contract volumetrically as they cool, thus, requiring narrower channels as they progress though the heat exchanger. - Referring now to
FIG. 8 an elevation view of thefin 24 a andcorresponding flue channel 22 a is shown.FIGS. 9 to 11 are sectional views taken along lines C-C, D-D, and E-E ofFIG. 8 . -
FIG. 9 shows aportion 46 of thefin 24 a extending radially from thefirst section 16 of thecentral chamber 12. The width W1 of theopening 40 in thefin 24 a is sufficient to allow the combustion gases to readily flow from thefirst section 16 of thecentral chamber 12, through thefin 24 a, and into theflue 22 a.FIG. 10 shows aportion 48 of thefin 24 a aligned withbaffle 20. In this situation theinner walls fin 24 a abut to prevent flue gases from flowing around baffle 20 through the fin 24. Flue gases from thefirst section 16 of the central chamber must therefore flow along theflue 22 a to bypass thebaffle 20.FIG. 11 shows aportion 50 of thefin 24 a as it appears when extending radially from thesecond section 18 of thecentral chamber 12. The width W2 of the opening when thefin 24 a extends radially from the second section of thecentral chamber 12 is less than the width W1 of thefin 24 a when it extends radially from thefirst section 16 of thecentral chamber 12. This results in the combustion gases tending to collect in theflue 22 a instead of flowing into thesecond portion 18 of thecentral chamber 12. This is desirable because it increases the surface area of theheat exchanger 10 which is in contact with the combustion gases. - Furthermore, this difference in the width of the
openings fin 24 a on opposite sides of thebaffle 20 provides for a graduated decline in combustion gas temperature with a more even distribution of heat transfer. The lower temperature quench rate also reduces accretions of impurities in the combustion gases on heat transfer surfaces, and spreads out those which do occur. This results in reduced sensitivity to flue blockages and cleaning requirements. As additional combustion gases flow into theflue 22 a and the pressure increases, the combustion gases will eventually flow into thesecond portion 18 of thecentral chamber 12 via thefin 24 a. The combustion gases then flow out of thesecond section 18 of thecentral chamber 12 as exhaust gases. - A mill certified coil strip of stainless steel having a fixed width is used to construct the
heat exchanger 10. The width of the strip will determine the height of theheat exchanger 10. The strip first is uncoiled allowing it to be stamped and folded to produce the blank 28 shown inFIGS. 4 and 5 . The blank 28 is brought around and the side ends are welded together to form thecentral chamber 12 of theheat exchanger 10 shown inFIG. 2 . This design allows for scaling since the diameter of theheat exchanger 10 is dependent on the length of the strip used. Alternatively, a plurality of blanks may be welded together to form theheat exchanger 10. The height of heat exchangers formed from the same coil strip of stainless steel will be constant. - In greater detail, and with reference to
FIGS. 2 and 4 , the stainless steel strip first passes through an in-line annealer to remove any work hardening induced through the manufacturing or coiling and uncoiling processes. From the annealer the strip is incrementally advanced through a stamping press that forms all the intricate features of theheat exchanger 10. All the turbulating and pressure reinforcing features of theheat exchanger 10 are formed in the blank 28 at this stage because tooling has easy access to the strip in flat form. In situations where a plurality ofblanks 28 are welded together a die in the stamping press consists of two half sections and, in particular, a left half section for stamping a first blank and a right half section for stamping an adjacent blank. This allows a seam that connects adjacent blanks to occur on the outside of the folded blank making it easier to weld. - A second stamping process cuts rounds 33 into the sections of the blank 28 that form the ends of the
flues rounds 33 allow edges of the blank 28 to meet for butt welding as will be discussed below. The next step involves forming the stamped sections of the strip into a fan like structure to form the blank 28 shown inFIG. 4 . Therounds 33 are drawn in to form the caps orfittings flues FIG. 2 . These two steps may be separated to allow for simpler tooling. It may also be desirable to incorporate an intermediate step to anneal the rounds to minimize the force required to form the caps orfittings - The blank 28 is cut to a desired length based on the desired diameter of the
heat exchanger 10 being constructed. The blank 28 is subject to cleaning and passivation prior to applying clamps (not shown) to form theflues fins - The last step involves clamping the blank to the point that the opposing faces of corresponding ones the divider stays 21 and channel stays 36 and 38 meet. The side edges of the blank 28 are rounded about the
baffle 20 and welded together. Spring back from the removal of the clamps is relieved by localized annealing of theflue channels heat exchanger 10 is still clamped. Thecomplete heat exchanger 10 is encased in a cylindrical boiler housing having ends with means to allow for the induction and exhaustion of combustion gases and ancillary sensor mountings. - In operation, the
heat exchanger 10 is disposed with a boiler housing (not shown) which contains a fluid being heated. Typically the fluid is water which pumped to flow in a direction opposite the direction in which the combustion gases flow through theheat exchanger 10. Combustion gases from a combustion chamber (not shown) flow into thefirst section 16 of thecentral chamber 12 as indicated byarrow 100 inFIG. 2 . Thebaffle 20 prevents the combustion gases from flowing directly from thefirst section 16 of thecentral chamber 12 into thesecond section 18 of thecentral chamber 12. Instead the combustion gases must flow radially outward from thefirst section 16 of thecentral chamber 12, via thefins flues flues baffle 20, as indicated byarrow 102 inFIG. 2 . This increases a surface area of theheat exchanger 10 on which heat may be transferred from the flue gases in theflues flues flues second section 18 of thecentral chamber 12. The combustion gases then flow out of thesecond section 18 of thecentral chamber 12 as indicated generally byarrow 104 inFIG. 2 . - The
heat exchanger 10 offers the advantage that thecentral chamber 12,flues fins heat exchanger 10 may be formed from a single blank 28 shown inFIGS. 4 and 5 . This may result in a decrease in manufacturing costs, particularly in costs associated with the assembly of the boiler, because of the reduced for welding and/or riveting. - Referring now to
FIG. 12 this shows a second embodiment of animproved heat exchanger 110. InFIG. 12 like parts have been given like reference numerals as in -
FIG. 2 with the additional prefix “1”, i.e. the central chamber is givenreference numeral 12 inFIG. 2 andreference numeral 112 inFIG. 12 , similarly the baffle is givenreference numeral 20 inFIG. 2 andreference numeral 120 inFIG. 12 . - The
heat exchanger 110 shown inFIG. 12 is generally similar to the heat exchanger shown inFIG. 2 with the exception that the second embodiment of theheat exchanger 110 is provided with a plurality of divider stays 121 a and 121 b which extend radial from thefirst section 116 of thecentral chamber 112. As shown for a first one of thefins 124 a, the second embodiment of theheat exchanger 110 is also provided with a plurality ofprotrusions FIGS. 12 to 17 . - A lowermost one of the divider stays 121 b is generally co-planar with the
baffle 120. Having a plurality of divider stays 121 a and 121 b above thebaffle 120 keeps the flow of combustion gases laminar and the pressure drop low. Combustion gases have the highest volumetric and linear flow rate in thefirst section 116 of theheat exchanger 110. Combustion gases also have the highest temperature and provide the highest heat flux infirst section 116 of theheat exchanger 110. Maintaining laminar flow helps reduce heat flux and prevent overloading of the fluid being heated. - The
protrusions inner wall 134 of the fins as best shown inFIG. 17 . Theprotrusions baffle 120 they will have cooled significantly and heat flux will be considerably lower. The turbulators enhance heat flux. In addition, the turbulators features help disperse any condensate allowing the flue gases direct contact with the surface of theheat exchanger 110. - It will be understood by a person skilled in the art that many of the details provided above are by way of example only, and are not intended to limit the scope of the invention, which is to be determined with reference to following claims.
Claims (9)
1. A heat exchanger for a boiler, the heat exchanger comprising:
a central chamber for receiving a combustion gas;
a baffle dividing the central chamber into a first section and a second section, the baffle restricting the combustion gas from flowing directly from the first section of the central chamber to the second section of the central chamber; and
a plurality of spaced-apart flues disposed about a periphery of the central chamber, the flues allowing for communication between the first section of the central chamber and the second section of the central chamber, and the flues allowing for combustion gas to flow from the first section of the central chamber to the second sections of the central chamber.
2. The heat exchanger as claimed in claim 1 wherein a fin extends between the central chamber and a corresponding one of the flues allowing for communication between the central chamber and said flue.
3. The heat exchanger as claimed in claim 2 wherein a width of the fin is longitudinally graduated.
4. The heat exchanger as claimed in claim 2 wherein the fin is provided with turbulators to enhance heat flux.
5. The heat exchanger as claimed in claim 2 wherein the fin is provided with a plurality of divider stays extending radially from the central chamber to maintain laminar flow of the combustion gas.
6. The heat exchanger as claimed in claim 1 wherein the central chamber and flues have a unitary structure and are formed from a single blank.
7. The heat exchanger as claimed in claim 1 wherein at least a portion of the central chamber and the flues disposed about said portion of the central chamber are formed from a single blank.
8. A boiler comprising:
a unitary heat transfer structure formed from a single blank, the blank being stamped and formed from a strip pulled from a slit coil of stainless steel, and the blank being pulled around to form a central chamber and longitudinal seamed to form a plurality of spaced-apart flues disposed about a periphery of the central chamber, the flues being in communication with the central chamber;
a baffle dividing the central chamber into a first section and a second section, the baffle restricting combustion gas from flowing directly from the first section of the central chamber to the second section of the central chamber;
an outer cylindrical boiler housing surrounding the unitary heat transfer structure, the housing having upper and lower with provisions for receiving and exhausting combustion gases; and
wherein a fluid being heated flows outside the unitary heat transfer structure and combustion gases flow within the unitary heat transfer structure in a counter flow direction as compared to the fluid being heated.
9. The heat exchanger as claimed in claim 8 wherein the flues are longitudinally and laterally graduated.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US12/756,381 US20100288209A1 (en) | 2009-04-08 | 2010-04-08 | heat exchanger for a boiler |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US16779709P | 2009-04-08 | 2009-04-08 | |
US12/756,381 US20100288209A1 (en) | 2009-04-08 | 2010-04-08 | heat exchanger for a boiler |
Publications (1)
Publication Number | Publication Date |
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US20100288209A1 true US20100288209A1 (en) | 2010-11-18 |
Family
ID=43067467
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US12/756,381 Abandoned US20100288209A1 (en) | 2009-04-08 | 2010-04-08 | heat exchanger for a boiler |
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US (1) | US20100288209A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140230869A1 (en) * | 2013-02-19 | 2014-08-21 | Gmz Energy, Inc. | Self-Powered Boiler Using Thermoelectric Generator |
US20180148827A1 (en) * | 2016-03-16 | 2018-05-31 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Thermal conduction device and vapor deposition crucible |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1046178A (en) * | 1911-09-07 | 1912-12-03 | Alexander Grant | Vertical hot-water heater. |
US4271789A (en) * | 1971-10-26 | 1981-06-09 | Black Robert B | Energy conversion system |
US4443188A (en) * | 1981-05-20 | 1984-04-17 | Bbc Brown, Boveri & Company, Ltd. | Liquid cooling arrangement for industrial furnaces |
US4909191A (en) * | 1988-07-05 | 1990-03-20 | Chaffoteaux Et Maury | Hot water production appliances |
US20060108109A1 (en) * | 2001-05-01 | 2006-05-25 | Julian Romero-Beltran | Plate-tube type heat exchanger |
US20070034367A1 (en) * | 2005-08-12 | 2007-02-15 | Wieder Horst K | Method and Apparatus for Heating and Cooling |
-
2010
- 2010-04-08 US US12/756,381 patent/US20100288209A1/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1046178A (en) * | 1911-09-07 | 1912-12-03 | Alexander Grant | Vertical hot-water heater. |
US4271789A (en) * | 1971-10-26 | 1981-06-09 | Black Robert B | Energy conversion system |
US4443188A (en) * | 1981-05-20 | 1984-04-17 | Bbc Brown, Boveri & Company, Ltd. | Liquid cooling arrangement for industrial furnaces |
US4909191A (en) * | 1988-07-05 | 1990-03-20 | Chaffoteaux Et Maury | Hot water production appliances |
US20060108109A1 (en) * | 2001-05-01 | 2006-05-25 | Julian Romero-Beltran | Plate-tube type heat exchanger |
US20070034367A1 (en) * | 2005-08-12 | 2007-02-15 | Wieder Horst K | Method and Apparatus for Heating and Cooling |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140230869A1 (en) * | 2013-02-19 | 2014-08-21 | Gmz Energy, Inc. | Self-Powered Boiler Using Thermoelectric Generator |
US20180148827A1 (en) * | 2016-03-16 | 2018-05-31 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Thermal conduction device and vapor deposition crucible |
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