CA1132023A - Combustion heater - Google Patents
Combustion heaterInfo
- Publication number
- CA1132023A CA1132023A CA324,352A CA324352A CA1132023A CA 1132023 A CA1132023 A CA 1132023A CA 324352 A CA324352 A CA 324352A CA 1132023 A CA1132023 A CA 1132023A
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- CA
- Canada
- Prior art keywords
- air
- combustion
- chamber
- exhaust
- tube
- 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.)
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Abstract
COMBUSTION HEATER
AB KAL POl JC/rc ABSTRACT OF THE DISCLOSURE
A wood burning combustion heater comprises a com-bustion chamber for long logs arranged to burn down from one end to the other in cigar-like fashion, an after-burner tube arrayed above and essentially parallel to the elongated logs with the air and burned gasses following an S-shaped path through the combustion chamber and out through the exhaust tube, an after-burner within said tube and a heat exchanger fed by the exhaust from said tube for heating air in indirect heat exchange and characterized further by an incoming air passage annulus surrounding the combustion chamber for pre-heating thereby;
multiple levels of air admission for controlling combustion;
electric ignition at the after-burner; bathing the exhaust tube, containing the after-burner, in flame through admission of secondary air to the region outside such tube; and high mass for even dissipation of heat.
AB KAL POl JC/rc ABSTRACT OF THE DISCLOSURE
A wood burning combustion heater comprises a com-bustion chamber for long logs arranged to burn down from one end to the other in cigar-like fashion, an after-burner tube arrayed above and essentially parallel to the elongated logs with the air and burned gasses following an S-shaped path through the combustion chamber and out through the exhaust tube, an after-burner within said tube and a heat exchanger fed by the exhaust from said tube for heating air in indirect heat exchange and characterized further by an incoming air passage annulus surrounding the combustion chamber for pre-heating thereby;
multiple levels of air admission for controlling combustion;
electric ignition at the after-burner; bathing the exhaust tube, containing the after-burner, in flame through admission of secondary air to the region outside such tube; and high mass for even dissipation of heat.
Description
3~ 3 BACKGROUND OF THE INVENTION
The present invention relates to wood fired com-; bustion heaters.
It is an important object of the invention to effectively utilize wood as a fuel for heating residencesrfactories, greenhouses, warehouses, and other buildings or spaces.
It is a further object of the invention to sub-stantially completely consume all combustibles of a wood fuel charge consistent with the preceding object.
It is a further object of the invention to provide economy of operation consistent with one or more of the pre-ceding objects.
It is a further object of the invention to provide effective burning rate and temperature controls consistent with one or more of the preceding objects.
It is a further object of the invention to separate heat production from heat removal and to have the hottest possible fire box environment for greater efficiency consiste~
with one or more of the preceding objects.
. It is a further object of the invention to pre-heat all the intake combustion air utilizing the normal radiant energy available from the firebox walls consistent with one or more of the preceding objects.
; 25 It is a further object of the invention to minimize pollutant generation consistent with one or more of the pre-ceding objects.
It is a further object of the invention to provide good usage of space in terms of effective heating ob~ained, consistent with one or more of the preceding objects of the invention.
The present invention relates to wood fired com-; bustion heaters.
It is an important object of the invention to effectively utilize wood as a fuel for heating residencesrfactories, greenhouses, warehouses, and other buildings or spaces.
It is a further object of the invention to sub-stantially completely consume all combustibles of a wood fuel charge consistent with the preceding object.
It is a further object of the invention to provide economy of operation consistent with one or more of the pre-ceding objects.
It is a further object of the invention to provide effective burning rate and temperature controls consistent with one or more of the preceding objects.
It is a further object of the invention to separate heat production from heat removal and to have the hottest possible fire box environment for greater efficiency consiste~
with one or more of the preceding objects.
. It is a further object of the invention to pre-heat all the intake combustion air utilizing the normal radiant energy available from the firebox walls consistent with one or more of the preceding objects.
; 25 It is a further object of the invention to minimize pollutant generation consistent with one or more of the pre-ceding objects.
It is a further object of the invention to provide good usage of space in terms of effective heating ob~ained, consistent with one or more of the preceding objects of the invention.
-2 ` ~3Z~Z3 . .
It is a further object of the invention to provide a fail-safe and useful mode of operation in the event of electrical power failure consistent with one or more of the preceding objects.
It is a further object of the invention to adapt to conventional or existing hot air duct work systems for spreading heated air throughout an installation.
It is a further object of the invention to provide a long time, at least eight hours, between stokings of the burner, consistent with one or more of the preceding objects.
It is a further object of the invention to substan-tially reduce hea-t loss up the chimney to below 250 consis-tent with one or more of the preceding objects.
It is a further object of the invention to reclaim energy spent to vaporize water from green wood by recondensa-tion consistent with one or more of the preceding objects.
It is a further object of the invention to dry out chimney gases to avoid harming chimneys by freezing out consistent with one or more of the preceding objects.
It is a further object of the invention to provide apparatus consistent with one or more of the preceding objects which is economical, transportable and easily installed and substantially maintainable by unskilled personnel and con-veniently.
It is a further object to electrically ignite any unburned smoke content in the exhaust.
It is a further object to provide for drainage of recondensed water from the burner of green wood.
SUM~r~Y OF THE INVENTION
According to the above objects, from a broad aspect, the present invention provides a cornbustion heater comprising means defining a combustion chamber with a lower space for holding an elongated solid fuel charge and means for feeding primary air and combustion gas products therefrom so that the charge burns from a forward towards a rear end. Means also defines an elongated combustion gas products conduit running above and substantially parallel to the fuel charge space and within the flame produced thereby. Means defines a heat ex-changer for receiving the exhaust of the conduit and extract-ing heat therefrom. Means is further provided for injecting secondary air into the combustion chamber outside of and adja-cent to the exhaust conduit to enhance flame coverage thereof.
Accord:iny to a further broad aspect of the present invention, there is provided a combustion heater with an S-draft gas flow pattern being established merely by an elon-gated solid fuel burning gradually back along its length and comprising means for lirniting combustion air to establish such gradual lengthwise burning.
According to a still further broad aspect of the present invention, there is provided a combustion heater com-prising primary combustion chamber means including means for injecting a limited amount of air therein to burn with a solid fuel charged therein~ A heat exchanger means is provided.
Conduit means is provided for conducting combustion products from the primary combustion chamber to the heat exchanger.
Means is also provided for producing after-burning secondary combustion in the conduit means b-y injecting secondary ~ir therein to burn with gaseous fuel content of the combustion products.
- 3a -' '' 1132~323 ~ ccording to a further broad aspect of the present invention, there is provided an improved furnace capable of burning moisture-containing wood comprising means defining a primary combustion chamber for burning such wood and convert-ing moisture therein to water vapor and generating combustion product from the wood per se. Means is also provided defining a separate heat exchanger for heat transfer between the water-vapor-containing combustion products and a flaming ambient via separating walls. The heat exchanger is con-structed and arranged to chill combustion gas therein tobelow 212F and recondense water vapor therein and drain the water vapor to avoid re-evaporation. Means is also provided for exhausting combustion products from the heat exchanger.
According to a still further broad aspect of the present invention, there is provided a method of heating gas comprising burning moisture-containing wood in one zone to produce water vapor-containing combustion products of wood , combustion. The combustion products are conveyed to a separate heat exchanger through multiple tubes in the heat exchanger.
Gas to be heated is passed over the tubes for indirect heat exchange with the moisture vapor-containing combustion pro-ducts. The vapor is condensed and drained. The combustion products are conducted away from the heat exchanger as an exhaust and the yas to be heated is conducted away from the heat exchanger to a point of use.
Further, in accordance with the invention, a primary com-bustion chamber is provided for insertion of logs, preferably of standard four foot cordwood length (an economical way to buy or cut firewood). 'rhe elongated combustion chamber is preferably fed from the front. ~n exhaust tube is provided therein in a high portion thereof, above and generally parallel - 3b -~ 3 to the logs, and has an opening at the rear of the combustionchamber. Air admission is limited so that the logs burn from front to back, rather than entirely along their lengths at once.
The resultant air and combustion product moves along an S-shaped flow path (including transit of the exhaust gassesthrough the after-burner tu~e). Within the after-burner tube, additional air is injected to create a new combustion therein.
Secondary air is injected into high regions of the combustion chamber parallel to the exhaust/after-burner tube so that there will be flames bathing the tube. In contrast, without such secondary air admission, there would be just smoke and hot air of considerably lower temperature around that tube.
Electric spark or glowplug ignition is provided within ~he exhaust/after-burner tube to maintain continuous af~erburning Whenever products of incomplete combustion are present.
The air for combustion is pre-heated and moved by passing around the combustion chamber itself (in heat exchange relation) before admission thereto, p;eferably through an annulus surrounding the combustion chamber with flow-directing ribs therein to assure a longitudinal component of flow and reduce hot spots in the firebox. The hot combustion creates suction draw of pre-heated combustion air and the forced drafting as a whole eliminates common chimney problems and allows for precise thermostatic control of temperature of the heated air. The pre-heating of air is used for all of the primary air, the secondary air and the after-burning air admission described above. Multiple fans are provided for force drafting, one running at all times to provide limited - 30 capacity air intake to barely sustain combustion ("idling"
- glow) and one or more other fans cut in to provide addition~l ..
AJc/KAcL P01 air to supplement the limited capacity first fan in response to alO/8/77 thermostat's signal call for higher room temperature or more air. The fans are electrically operated, but in the event of a power failure, the furnace itself maintains sufficient heat from its high mass and natural suction draw to operate for a while.
The exhaust/after-burner tube exits immediately into an indirect heat exchanger comprising an inlet plenum, an outlet plenum and, therebetween, a multiplicity of tubes with a high surface area to a volume ratio of exhaust gas passage.
Domestic air to be heated passes over such tubes and then into the regions of the room to be hea~ed. In addition to ductwork conveying the heated air to various locations desired to be heated, the structure of the combustion chamber itself and of the heat exchanger comprise a source of significant heat for the surrounding room area. Such structures are made massive to constitute a built-in heat reservoir (or virtual flywheel effect) to evenly dissipate heat over a wide time span pro-viding a more constant room temperature at any given control setting of air admissions. The primary control is through electrically varying one or more of the above described forced draft fans. This is adjusted by the remote control thermostat.
Also, an automatic shut-down of combustion at the end of the fuel supply is provided through monitoring exhaust temperature through a thermostat on the wall of the final exhaust tube to shut off air supplies and to shut down electrical ignition upon consumption of fuel an alarm or indicator to show that more stoking ~wood reloading) is necessary can also be activated by the thermostat.
The primary chamber combustion produces a total com-bustion of solids and results in a light gray to white powderash, indicative of an extremely lean and thorough burn. Minor ~L32~3 unburned solids remain at times. Moisture and volatile gasses contained within the wood fuel are continuously driven off.
Air admitted for the primary combustion and secondary combustion described above is pre-heated beyond the wood ignition tempera-ture per se and ignites many of the volatile gasses for more complete heat production and to avoid chimney and pollution problems. Hot oxygen-rich air is provided to lean flame tips to produce a blue lazy tipped flame resulting in measurable increase in heat output and observed improvement in color and reduction of exhaust emissions at the chimney. The exhaust is clear and cool.
Because of high combustion efficiency and heat trans-fer efficiency and large wood charge, typical models made in accordance with the invention can burn for 12-36 hours without stoking, variable by control of inlet air. Efficiency is further enhanced by extracting almost all the imparted heat from exhaust gas. It is chilled to well below 212F. Moisture from the wood is converted to water vapor (steam) in the primary combustion chamber and after-burner and is recondensed 2Q in the heat exchanger and rapidly drained to avoid re-evapora-tion. The final exhaust is dry and doesn't condense out on the chimney to any substantial degree. The condensation represents a return of heat to the system to make up to the system, at least in part, the energy originally used to vapor-ize the moisture content of wood.
The primary combustion chamber, including a pre-heating annulus -therein for inlet air, and the heat exchanger constitute an easily transportable, p~e-assembled, easily installed structure.
In accordance with a particular em~odiment of the invention a combustion heater comprises: first means defining 1~3~Z~3 a combustion chamber with inner and outer walls and an annulus therebetween and with a lower spa_e within the inner wall having a forward end and rear end for holding an elongated solid fuel charge and means for feeding primary air thereto and combustion gas products therefrom both at said forward end so that the charge burns from said forward towards said rear end of said chamber, second means defining an elongated com~ustion gas products conduit running above and substantially parallel to the fuel charge spa_e and within -the flame produced thereby . 10 and having an entrance for combustion gas products of said first means, said first and second means being arranged to define an S-draft gas flow pa-th, means defining a principal heat exchanger for receiving the exhaust of said conduit and extracting heat therefrom, and means for injecting secondary air into the combustion chamber outside of and adjacent to the exhaust conduit at multiple points along the length thereof to enhance flame coverage thereof, means for producing after-burning in said conduit by injecting secondary air therein at a point downstream of the conduit entrance, and means for pre-heating the primary air and secondary air and after-burner air in counter-current heat exchange in said combustion chamber annulus by injection to said annulus at the combustion chamber rear end and movement to said forward end.
Other objects, features and advantages of the invention will be apparent from the following detailed .:
- 6a -1~3~23 ~AB KAL P01 description of preferred embodiments thereof, taken in 10/8/77 connection with the accompanying drawing, in which, BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal section of a preferred embodiment of the invention and FIG. 2 is a lateral cross section thereof, taken as indicated at 2-2 in FIG. 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to FIGS. 1 and 2, there is shown the above described primary combustion chamber 10 and the above ' described heat exchanger 20 and air and exhaust gas ductwork 30. ~ 31 + 32 + 23.
The primary combustion chamber 10 comprises an inner chamber 12, an outer wall 14, with an annulus 16 there-between containing longitudinally extending fins 15 fordirecting air (which enters at inlet 11) essentially longi-tudinally along the outer wall of inner chamber 12. Inner chamber 12 has a lower region 121 containing logs L and an upper region 122~ Within the inner chamber upper portion 122, there is an after-burner/exhaust tube 18. Primary air for combustion comes to the primary combustion chamber via annulus 16 and two or more spaced pipes 161 (elbows). Secondary air - for the upper portion 122, comes from annulus 16 via two or more spaced pipes 162 (elbows). Similarly, the elbow pipe 163 provides the after-burnerair from space 16to tube 18. The second~ry air pipes 162have holes along their lengths as they run parallel to the e~haust/after-burner tube. Air fed into these pipes induces the complete combustion which causes flames to reach out and touch the pipe 18 as indicated at FL in FIG. 2.
In the absence of the secondary air, the flames would be lower and less consistent inreaching pipe 18 to maintain it very hot.
JC/rc Inlet air comes through pipes llA and llB, each of which have 10/8/77 a fan F therein, one of which continually operates and the other which is selectively controlled. Both are electrically driven. The idle air provided by the continuous fan provides ` 5 just enough combustion air to maintain a rekindleable fire (glow) and the second fan provides to the fire more than twice as much air as the idle situation to speed up combustion, producing greater flames and heat. A circulator fan (not shown~ is provided in the heat exchanger system and can be set 10 to run at one speed, at different selected C.F.~I.
The heat exchanger 20 comprises an inlet plenum 21, an exhaust plenum 22 for waste gasses and an exit 23 to the smokestack and air inlet and outlet passages 31 and 32, respectiveIy. An electric spark igniter for the after-burner 15 is indicated at I and has an electrical power supply PS
externally (which may be alternating or a connection to house power via a transformer). Preferably it operates con-tinuously, but it may be provided with a switch for selective use of the exhaust after-burning.
Typical dimensions and construction parameters for a unit which has been operated effectively are -- one-half inch thick steel, 100% welded primary chamber and a 3/8 inch thick steel 100% welded heat exchanger. The primary and secondary chambers are about 4.5 ft. long each and each is less than 3 ft. in diameter. They have a total weight of the two of about one and one-half tons.
A front plate Pl of the primary chamber contains a loading door Dl of about 17 X 12 inches, within a cleanout - door of circular form and about 23 inches diameter, both being hinged. Typically, the circulator/blower will handle 2,000 cu.
ft. per minute up to 100 ft. of 12" ductwork or equivalent.
:
~3~3 :
AB KAL POl The furnace described above can be integrated with JC/rc 10/8/77 other heating systems or used for purposes other than domestic heating, and in turn, can borrow from existing components for implementation at any given installation.
It is evident that those skilled in the art, once given the benefit of the foregoing disclosure, may now make numerous other uses and modifications of, and departures from the specific embodiments described herein without departing from the inventive concepts. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features present in, or possessed by, the apparatus and techniques herein disclosed and limited solely by the ecope and spirit of the appended claims.
'.~' ':
.
_9_ ','' ... . .
It is a further object of the invention to provide a fail-safe and useful mode of operation in the event of electrical power failure consistent with one or more of the preceding objects.
It is a further object of the invention to adapt to conventional or existing hot air duct work systems for spreading heated air throughout an installation.
It is a further object of the invention to provide a long time, at least eight hours, between stokings of the burner, consistent with one or more of the preceding objects.
It is a further object of the invention to substan-tially reduce hea-t loss up the chimney to below 250 consis-tent with one or more of the preceding objects.
It is a further object of the invention to reclaim energy spent to vaporize water from green wood by recondensa-tion consistent with one or more of the preceding objects.
It is a further object of the invention to dry out chimney gases to avoid harming chimneys by freezing out consistent with one or more of the preceding objects.
It is a further object of the invention to provide apparatus consistent with one or more of the preceding objects which is economical, transportable and easily installed and substantially maintainable by unskilled personnel and con-veniently.
It is a further object to electrically ignite any unburned smoke content in the exhaust.
It is a further object to provide for drainage of recondensed water from the burner of green wood.
SUM~r~Y OF THE INVENTION
According to the above objects, from a broad aspect, the present invention provides a cornbustion heater comprising means defining a combustion chamber with a lower space for holding an elongated solid fuel charge and means for feeding primary air and combustion gas products therefrom so that the charge burns from a forward towards a rear end. Means also defines an elongated combustion gas products conduit running above and substantially parallel to the fuel charge space and within the flame produced thereby. Means defines a heat ex-changer for receiving the exhaust of the conduit and extract-ing heat therefrom. Means is further provided for injecting secondary air into the combustion chamber outside of and adja-cent to the exhaust conduit to enhance flame coverage thereof.
Accord:iny to a further broad aspect of the present invention, there is provided a combustion heater with an S-draft gas flow pattern being established merely by an elon-gated solid fuel burning gradually back along its length and comprising means for lirniting combustion air to establish such gradual lengthwise burning.
According to a still further broad aspect of the present invention, there is provided a combustion heater com-prising primary combustion chamber means including means for injecting a limited amount of air therein to burn with a solid fuel charged therein~ A heat exchanger means is provided.
Conduit means is provided for conducting combustion products from the primary combustion chamber to the heat exchanger.
Means is also provided for producing after-burning secondary combustion in the conduit means b-y injecting secondary ~ir therein to burn with gaseous fuel content of the combustion products.
- 3a -' '' 1132~323 ~ ccording to a further broad aspect of the present invention, there is provided an improved furnace capable of burning moisture-containing wood comprising means defining a primary combustion chamber for burning such wood and convert-ing moisture therein to water vapor and generating combustion product from the wood per se. Means is also provided defining a separate heat exchanger for heat transfer between the water-vapor-containing combustion products and a flaming ambient via separating walls. The heat exchanger is con-structed and arranged to chill combustion gas therein tobelow 212F and recondense water vapor therein and drain the water vapor to avoid re-evaporation. Means is also provided for exhausting combustion products from the heat exchanger.
According to a still further broad aspect of the present invention, there is provided a method of heating gas comprising burning moisture-containing wood in one zone to produce water vapor-containing combustion products of wood , combustion. The combustion products are conveyed to a separate heat exchanger through multiple tubes in the heat exchanger.
Gas to be heated is passed over the tubes for indirect heat exchange with the moisture vapor-containing combustion pro-ducts. The vapor is condensed and drained. The combustion products are conducted away from the heat exchanger as an exhaust and the yas to be heated is conducted away from the heat exchanger to a point of use.
Further, in accordance with the invention, a primary com-bustion chamber is provided for insertion of logs, preferably of standard four foot cordwood length (an economical way to buy or cut firewood). 'rhe elongated combustion chamber is preferably fed from the front. ~n exhaust tube is provided therein in a high portion thereof, above and generally parallel - 3b -~ 3 to the logs, and has an opening at the rear of the combustionchamber. Air admission is limited so that the logs burn from front to back, rather than entirely along their lengths at once.
The resultant air and combustion product moves along an S-shaped flow path (including transit of the exhaust gassesthrough the after-burner tu~e). Within the after-burner tube, additional air is injected to create a new combustion therein.
Secondary air is injected into high regions of the combustion chamber parallel to the exhaust/after-burner tube so that there will be flames bathing the tube. In contrast, without such secondary air admission, there would be just smoke and hot air of considerably lower temperature around that tube.
Electric spark or glowplug ignition is provided within ~he exhaust/after-burner tube to maintain continuous af~erburning Whenever products of incomplete combustion are present.
The air for combustion is pre-heated and moved by passing around the combustion chamber itself (in heat exchange relation) before admission thereto, p;eferably through an annulus surrounding the combustion chamber with flow-directing ribs therein to assure a longitudinal component of flow and reduce hot spots in the firebox. The hot combustion creates suction draw of pre-heated combustion air and the forced drafting as a whole eliminates common chimney problems and allows for precise thermostatic control of temperature of the heated air. The pre-heating of air is used for all of the primary air, the secondary air and the after-burning air admission described above. Multiple fans are provided for force drafting, one running at all times to provide limited - 30 capacity air intake to barely sustain combustion ("idling"
- glow) and one or more other fans cut in to provide addition~l ..
AJc/KAcL P01 air to supplement the limited capacity first fan in response to alO/8/77 thermostat's signal call for higher room temperature or more air. The fans are electrically operated, but in the event of a power failure, the furnace itself maintains sufficient heat from its high mass and natural suction draw to operate for a while.
The exhaust/after-burner tube exits immediately into an indirect heat exchanger comprising an inlet plenum, an outlet plenum and, therebetween, a multiplicity of tubes with a high surface area to a volume ratio of exhaust gas passage.
Domestic air to be heated passes over such tubes and then into the regions of the room to be hea~ed. In addition to ductwork conveying the heated air to various locations desired to be heated, the structure of the combustion chamber itself and of the heat exchanger comprise a source of significant heat for the surrounding room area. Such structures are made massive to constitute a built-in heat reservoir (or virtual flywheel effect) to evenly dissipate heat over a wide time span pro-viding a more constant room temperature at any given control setting of air admissions. The primary control is through electrically varying one or more of the above described forced draft fans. This is adjusted by the remote control thermostat.
Also, an automatic shut-down of combustion at the end of the fuel supply is provided through monitoring exhaust temperature through a thermostat on the wall of the final exhaust tube to shut off air supplies and to shut down electrical ignition upon consumption of fuel an alarm or indicator to show that more stoking ~wood reloading) is necessary can also be activated by the thermostat.
The primary chamber combustion produces a total com-bustion of solids and results in a light gray to white powderash, indicative of an extremely lean and thorough burn. Minor ~L32~3 unburned solids remain at times. Moisture and volatile gasses contained within the wood fuel are continuously driven off.
Air admitted for the primary combustion and secondary combustion described above is pre-heated beyond the wood ignition tempera-ture per se and ignites many of the volatile gasses for more complete heat production and to avoid chimney and pollution problems. Hot oxygen-rich air is provided to lean flame tips to produce a blue lazy tipped flame resulting in measurable increase in heat output and observed improvement in color and reduction of exhaust emissions at the chimney. The exhaust is clear and cool.
Because of high combustion efficiency and heat trans-fer efficiency and large wood charge, typical models made in accordance with the invention can burn for 12-36 hours without stoking, variable by control of inlet air. Efficiency is further enhanced by extracting almost all the imparted heat from exhaust gas. It is chilled to well below 212F. Moisture from the wood is converted to water vapor (steam) in the primary combustion chamber and after-burner and is recondensed 2Q in the heat exchanger and rapidly drained to avoid re-evapora-tion. The final exhaust is dry and doesn't condense out on the chimney to any substantial degree. The condensation represents a return of heat to the system to make up to the system, at least in part, the energy originally used to vapor-ize the moisture content of wood.
The primary combustion chamber, including a pre-heating annulus -therein for inlet air, and the heat exchanger constitute an easily transportable, p~e-assembled, easily installed structure.
In accordance with a particular em~odiment of the invention a combustion heater comprises: first means defining 1~3~Z~3 a combustion chamber with inner and outer walls and an annulus therebetween and with a lower spa_e within the inner wall having a forward end and rear end for holding an elongated solid fuel charge and means for feeding primary air thereto and combustion gas products therefrom both at said forward end so that the charge burns from said forward towards said rear end of said chamber, second means defining an elongated com~ustion gas products conduit running above and substantially parallel to the fuel charge spa_e and within -the flame produced thereby . 10 and having an entrance for combustion gas products of said first means, said first and second means being arranged to define an S-draft gas flow pa-th, means defining a principal heat exchanger for receiving the exhaust of said conduit and extracting heat therefrom, and means for injecting secondary air into the combustion chamber outside of and adjacent to the exhaust conduit at multiple points along the length thereof to enhance flame coverage thereof, means for producing after-burning in said conduit by injecting secondary air therein at a point downstream of the conduit entrance, and means for pre-heating the primary air and secondary air and after-burner air in counter-current heat exchange in said combustion chamber annulus by injection to said annulus at the combustion chamber rear end and movement to said forward end.
Other objects, features and advantages of the invention will be apparent from the following detailed .:
- 6a -1~3~23 ~AB KAL P01 description of preferred embodiments thereof, taken in 10/8/77 connection with the accompanying drawing, in which, BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a longitudinal section of a preferred embodiment of the invention and FIG. 2 is a lateral cross section thereof, taken as indicated at 2-2 in FIG. 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to FIGS. 1 and 2, there is shown the above described primary combustion chamber 10 and the above ' described heat exchanger 20 and air and exhaust gas ductwork 30. ~ 31 + 32 + 23.
The primary combustion chamber 10 comprises an inner chamber 12, an outer wall 14, with an annulus 16 there-between containing longitudinally extending fins 15 fordirecting air (which enters at inlet 11) essentially longi-tudinally along the outer wall of inner chamber 12. Inner chamber 12 has a lower region 121 containing logs L and an upper region 122~ Within the inner chamber upper portion 122, there is an after-burner/exhaust tube 18. Primary air for combustion comes to the primary combustion chamber via annulus 16 and two or more spaced pipes 161 (elbows). Secondary air - for the upper portion 122, comes from annulus 16 via two or more spaced pipes 162 (elbows). Similarly, the elbow pipe 163 provides the after-burnerair from space 16to tube 18. The second~ry air pipes 162have holes along their lengths as they run parallel to the e~haust/after-burner tube. Air fed into these pipes induces the complete combustion which causes flames to reach out and touch the pipe 18 as indicated at FL in FIG. 2.
In the absence of the secondary air, the flames would be lower and less consistent inreaching pipe 18 to maintain it very hot.
JC/rc Inlet air comes through pipes llA and llB, each of which have 10/8/77 a fan F therein, one of which continually operates and the other which is selectively controlled. Both are electrically driven. The idle air provided by the continuous fan provides ` 5 just enough combustion air to maintain a rekindleable fire (glow) and the second fan provides to the fire more than twice as much air as the idle situation to speed up combustion, producing greater flames and heat. A circulator fan (not shown~ is provided in the heat exchanger system and can be set 10 to run at one speed, at different selected C.F.~I.
The heat exchanger 20 comprises an inlet plenum 21, an exhaust plenum 22 for waste gasses and an exit 23 to the smokestack and air inlet and outlet passages 31 and 32, respectiveIy. An electric spark igniter for the after-burner 15 is indicated at I and has an electrical power supply PS
externally (which may be alternating or a connection to house power via a transformer). Preferably it operates con-tinuously, but it may be provided with a switch for selective use of the exhaust after-burning.
Typical dimensions and construction parameters for a unit which has been operated effectively are -- one-half inch thick steel, 100% welded primary chamber and a 3/8 inch thick steel 100% welded heat exchanger. The primary and secondary chambers are about 4.5 ft. long each and each is less than 3 ft. in diameter. They have a total weight of the two of about one and one-half tons.
A front plate Pl of the primary chamber contains a loading door Dl of about 17 X 12 inches, within a cleanout - door of circular form and about 23 inches diameter, both being hinged. Typically, the circulator/blower will handle 2,000 cu.
ft. per minute up to 100 ft. of 12" ductwork or equivalent.
:
~3~3 :
AB KAL POl The furnace described above can be integrated with JC/rc 10/8/77 other heating systems or used for purposes other than domestic heating, and in turn, can borrow from existing components for implementation at any given installation.
It is evident that those skilled in the art, once given the benefit of the foregoing disclosure, may now make numerous other uses and modifications of, and departures from the specific embodiments described herein without departing from the inventive concepts. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features present in, or possessed by, the apparatus and techniques herein disclosed and limited solely by the ecope and spirit of the appended claims.
'.~' ':
.
_9_ ','' ... . .
Claims (4)
1. Combustion heater comprising first means defining a combustion chamber with inner and outer walls and an annulus therebetween and with a lower space within the inner wall having a forward end and rear end for holding an elongated solid fuel charge and means for feeding primary air thereto and combustion gas products there-from both at said forward end so that the charge burns from said forward towards said rear end of said chamber, second means defining an elongated combustion gas products conduit running above and substantially parallel to the fuel charge space and within the flame produced thereby and having an entrance for combustion gas products of said first means, said first and second means being arranged to define an S-draft gas flow path, means defining a principal heat exchanger for receiving the exhaust of said conduit and extracting heat therefrom, and means for injecting secondary air into the combus-tion chamber outside of and adjacent to the exhaust conduit at multiple points along the length thereof to enhance flame coverage thereof, means for producing after-burning in said conduit by injecting secondary air therein at a point downstream of the conduit entrance, and means for preheating the primary air and secondary air and after-burner air in counter-current heat exchange in said combustion chamber annulus by injection to said annulus at the combustion chamber rear end and movement to said forward end.
2. Combustion heater in accordance with claim 1 wherein said last mentioned means comprise means defining an annular space around said combustion chamber and means therein for creating a tortuous flow path for air therein.
3. Combustion heater in accordance with claim 1 com-prising means for passing air to be burned first over the com-bustion chamber in heat exchange relation therewith and then into the chamber and then passing the combustion products through the said principal heat exchanger with surfaces and operating conditions adjusted so that all of the heat input into the air to be heated is obtained from the said principal heat exchanger.
4. Combustion heater in accordance with claim 1 wherein an air jacket is provided to hold the walls of the combustion chamber above ambient temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA324,352A CA1132023A (en) | 1979-03-28 | 1979-03-28 | Combustion heater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA324,352A CA1132023A (en) | 1979-03-28 | 1979-03-28 | Combustion heater |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1132023A true CA1132023A (en) | 1982-09-21 |
Family
ID=4113854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA324,352A Expired CA1132023A (en) | 1979-03-28 | 1979-03-28 | Combustion heater |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1132023A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102374555A (en) * | 2010-08-15 | 2012-03-14 | 吉松超 | Energy-saving, environment-friendly, easy-dusting, air-heated civil boiler |
-
1979
- 1979-03-28 CA CA324,352A patent/CA1132023A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102374555A (en) * | 2010-08-15 | 2012-03-14 | 吉松超 | Energy-saving, environment-friendly, easy-dusting, air-heated civil boiler |
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