CA1164745A - Wood burning assembly - Google Patents
Wood burning assemblyInfo
- Publication number
- CA1164745A CA1164745A CA000386907A CA386907A CA1164745A CA 1164745 A CA1164745 A CA 1164745A CA 000386907 A CA000386907 A CA 000386907A CA 386907 A CA386907 A CA 386907A CA 1164745 A CA1164745 A CA 1164745A
- Authority
- CA
- Canada
- Prior art keywords
- fuel
- combustion chamber
- assembly according
- combustion
- grate
- 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.)
- Expired
Links
Classifications
-
- 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
- F23M11/00—Safety arrangements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Solid-Fuel Combustion (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE A wood burning assembly or furnace for fuel in the form of slabs or log lengths. The assembly has a combustion chamber provided with a grate and primary and secondary inlet ports, and an ash receptacle is positioned beneath the grate, and a grate clos-ure plate is slidably mounted with respect to the grate enabling selected opening and closing thereof. A feed tunnel for the supply of fuel opens into the combustion chamber and means are provided within the feed tunnel to continuously advance the fuel to the combustion chamber. A movable abutment plate is provided in the combustion chamber at a position opposite to the feed tunnel, and the abutment plate is interconnected with drive means for the means to advance the fuel to control the rate of advance into the combus-tion chamber. Means are provided in the feed tunnel adjacent the combustion chamber to inhibit combustion of the fuel prior to its introduction into the combustion chamber.
Description
7-~ 5 The pr~sent invention relates to a wood burniny Eurnace or assembly Eor the combustion of Euel in the Eorm of slabs or log lengths in continuous manner.
Furnaces or combustion assemblies having a combustion chamber with a fuel feed and primary and secondary air inlet open-ings and an ash receptable beneath the combustion chamber are well known.
However, such known assemblies are not suitable for being continuously fed with and the burning of wood fuel which is in the form of slabs or log lengths in the order of approximately 1 to 1.5 metres long.
Moreover, the continuous combustion of fuel of this type presents difficulties particularly with respect to the following:
1. The rate of feed of the fuel must be consistent with the rate of combustion, and
Furnaces or combustion assemblies having a combustion chamber with a fuel feed and primary and secondary air inlet open-ings and an ash receptable beneath the combustion chamber are well known.
However, such known assemblies are not suitable for being continuously fed with and the burning of wood fuel which is in the form of slabs or log lengths in the order of approximately 1 to 1.5 metres long.
Moreover, the continuous combustion of fuel of this type presents difficulties particularly with respect to the following:
1. The rate of feed of the fuel must be consistent with the rate of combustion, and
2. Burning of the wood fuel along a feed pass and prior to its introduction into the combustion chamker must be prevented.
In addition such a furnace must be capable of successful operation and control whether the fuel be dry, or damp, or wet, and in this regard, and when the fuel is wet or damp,environmental considerat-ions are important and the formation and discharge of smoke and other pollutants must be minimized as much as possible.
It is absolutely essential that these problems and diffi-culties be overcome if one is to satisfactorily continuously operate a wood burning assembly which is continuously fed with fuel.
The prime purpose of the present invention then is to pro-vide a wood burning furnace or assembly which avoids the inherent disadvantages of furnaces of this general type and which enables the continuous combustion of fuel in the form of slabs or long . ~ .
.
i ~ ~;47~
lengths which are Eed to a combustion chamber in continuous manner and which inhibits combus-tion or pre-igni-tion of the fuel during the travel along the feed path and before introduction into the combustion chamber.
Applicant has established through experimentation that the present assembly (depending upon the length of the feed path and the volume of fuel) provides continuous operation for up to 10 to 12 hours with only two fillings of the assembly. In the pilot furnace constructed and operated, the feed supply tunnel was approx-imately four metres long having a cross-section area of approximately .25 square metres.
During the combustion of fuel which is continuously fed to a combustion chamber, the danger of pre-ignition and combustion of the fuel prior to its introduction into the combustion chamber is always present. This is particularly true in the case of dry fuel, but the danger still exists even when the fuel is wet or damp, inasmuch as the fuel becomes dried during its travel in the feed tunnel as a result of heat radiating from the combustion chamber and the resultant heating of the completed assembly. Drying of wet or damp fuel in the feed tunnel is also increased as a result of the spaces or gaps between the pieces of wood in the feed tunnel, and which enable the circulation of warm drying air. To minimize the extent of these gaps or spaces, it is preferred that at least the bottom portion of the combustion chamber and at least an adja-cent portion of the feed tunnel being of semi-circular cross-sec-tion so that the fuel can become compacted as much as possible.
The more the fuel is compacted, the less is the danger of pre-ignition or pre-combustion and the presentation of fuel pieces in concentrated manner into the combustion chamber greatly enhances ~ .
~ 3 ~ 4 7 ~ r) the rate of combustion.
The present invention avoids the inherent disadvantages of the prior art arrangements and fully satisfies all requirements for an assembly of this type by specifically providing a wood burn-ing assembly for fuel in the form of slabs or log lengths comprising a combustion chamber with a grate and primary and secondary air inlet ports, and an ash receptacle beneath the grate, and a grate closure plate slideably mounted with respect to the grate enabling selected opening and closing thereof, and a feed tunnel opening into the combustion chamber and means within the feed tunnel to advance the fuel to the com-bustion chamber and a movable abutment plate in the combustion chamber at a position opposite to the feed tunnel, the abutment plate being interconnected with drive means for the means to advance the fuel to control rate of advance of the fuel into the combustion chamber, and means in the feed tunnel adjacent the combustion chamber to inhibit combustion of the fuel prior to its introduction into the combustion chamber.
The invention will now be more fully described with ref-erence to the accompanying drawings wherein:
Figure 1 is a side sectional view of one embodiment of the present invention;
Figure 2 is a sectional view taken along line II-II of Figure l;
Figure 3 is a sectional view taken generally along line III-III of Figure 1, illustrating a preferred embodiment;
Figure 4 is a side sectional view taken along line IV-IV
of Figure 3;
Figure 5 is a sectional view taken generally along line ~ lfi~7~1S
V-V oE Figure l;
Figure 6 is a side sectlonal view of a combust:ion chamber and adjacent portion of a feed tunnel showing the arrangement of air inlet control elements; and Figure 7 is a side sectional view oE a preE~rre(l constrwct-ion of the present inventive concept.
The accompanying drawings will now be discussed in detail and wherein like reference numerals refer to like parts.
Numeral 1 indicates a feed tunnel which opens in the area shown at 2 into a combustion chamber 9. The feed tunnel has a fill-ing door 24, and the combustion chamber has door 3 and a grate 5 be-neath which is positioned an ash receptacle 22.
A combustion gas discharge duct 21 is positioned above the combustion chamber leading into a heat exchanger 25 which may be of the air or water type. The heat exchanger 25 may be in the form of a boiler, and due to environmental considerations a smoke and poll-utant extractor may also be provided.
The feed tunnel 1 is provided with fuel advancing means which may be in the form of an endless chain conveyor 20, positioned within a safety hood 20'. The conveyor is driven by motor means (not shown) and additionally may be provided with a crank '' for filling purposes. The conveyor 20 carries conveyor plate 23 which is pivotally mounted thereon for pivoting movement only in the di-rection of arrow A as shown. The plate 23 is of a dimension which generally fills the interior of the feed tunnel. The pivoted mount-ing of the plate 23 enables the feed tunnel to be filled by insert-ing fuel through door 24 and its securement against movement in a direction opposite to arrow A enables it to advance wood fuel along the feed tunnel during continuous operation of the conveyor 20 at i ~ fi 4 7 ~1 r~
very slow speed. rrhe conveyor may be mountecl elther above the ~eed tunnel as shown or beneath it, and the aclvancing mechanism may take different forms such as a screw feed positioned in the bottom of the tunnel to advance the wood to the combustion chamber. The conveyor means continuously advances the wood at a very low rate of speed dependent upon the speed of combustion of the wood within the com-bustion chamber.
Positioned within the combustion chamber 9 opposite to the entrance of the feed tunnel is a movable abutment plate 4 which carries a rod 11 which extends exteriorly of the combustion chamber to a position adjacent a limit switch 12. The abutmen plate 4 is biased to the position shown in Figure 1 by the provision of spring 11'. Pressure against abutment plate 4 by the advancing wood pieces moves the plate against the tension of spring 11, and the wood is continuously advanced by the conveyor until such time as rod 11 con-tacts limit switch 12 which is electrically interconnected with the drive means (not shown) of the conveyor 20. Closing of the limit switch 12 by rod 11 stops the conveyor drive, and commencement of the conveyor drive occurs when the force of fuel against the abut-ment plate 4 is removed (as a result of the burning of fuel) andthe rod 11 is withdrawn from the limit switch 12 under the action of spring 11'. Interconnection between the limit switch 12 may either be electrically as described or by the use of a Bowden cable.
Figure 2 shows that the interior of the feed tunnel may be rectangular. However, and as shown in the preferred embodiment of Figure 3, at least the lower portion of the combustion chamber and the adjacent portion of the feed tunnel are of generally semi-circular cross-section. This arrangement is also shown in Figure 5, and from which it will be noted that the grate 5 is also of semi-~ -5 1 ~ ~1 7 llr ~ ~
circular configura-tlcn and that khe grate ~ArS extelld irl the d:i-rection of movement of -the fuel.
~ n a further preferred embodiment, the combustion chamber and adjacent portion of the feed tunnel are provided with guide members 10 with the dlstance between the oppositely positioned guide members decreasing in the direction of advance oE the wood fuel. The semi-circular configuration of the combustion chamber and the provision of the guide element 10 compress the wood fuel as much as possible within the combustion chamber providing for a much more concentrated combustion.
Numeral 7 generally indicates various means to inhibit pre-ignition and combustion of the fuel within the feed tunnel, these means consisting of water sprinkler 13, dished depression 14, and at least one downwardly depending flexible skirt or feely pivoted flap or flaps 26, all as clearly shown in Figure 4. These elements combine to inhibit combustion of the fuel within the tunnel in the area shown by numeral 27.
Operation of the water sprinkler 13 may suitably be con-trolled by thermal probe 13' which controls supply valve 13''. se-neath sprinkler 13 is provided a dished depression 14 which prefer-ably is provided with an inclined surface 19 to guard against the jamming of wood.
An upper covering for grate 5 is not considered to be necessary inasmuch as the covering could become blocked by small fragments of wood or bark. Due to the provision of inclined sur-face 19, any accumulated fragments are simply moved ahead by the advancing fuel into the combustion chamber.
Beneath grate 5 a movable grate closure plate 6 is pro-vided and as shown in Figure 5, the plate 6 may have semi-circular fi47~5 configurations.
Due to the constituent nature oE the wood fuel, and rela-tive degree of dryness and thickness, uniform combustion of the fuel is not possible with the result that slower burning pieces will be advanced into the combustion chamber at a speed greater than their degree of combustion, and without some control over the con-veyor operation a jam of wood within the combustion chamber could occur. Abutment plate 4 acting on limit switch 12 to stop conveyor feed for a short time avoids this difficulty. As soon as pressure against abutment plate 4 is removed due to combustion, the conveyor resumes movement.
As discussed above, the guide elements 10 compact the ad-vancing fuel as much as possible to provide a concentrated combustion mass. In addition, however, the elements 10 act to lift the lower-most pieces of the advancing fuel to a somewhat inclined direction of feed so that they can advance further into the combustion chamber before contacting abutment plate 4.
In addition to providing for a more concentrated combus-tion, the semi-circular configuration of the combustion chamber and at least an adjacent portion of the feed tunnel minimizes the spaces between the fuel pieces and this has the effect of inhibiting com-bustion of the fuel within the feed tunnel. Pre-ignition, and pre-combustion of the fuel within the feed tunnel can be minized by this arrangement but can never be completely eliminated. To further inhibit this pre-combustion, the elements 7 as discussed above are provided in the feed tunnel adjacent the combustion chamber. The skirt or flap 26 which is freely pivotally mounted lies against the upper pieces of wood and this minimizes the radi-ation of heat from the combustion chamber along the feed tunnel.
`i I ~47~ 5 This skirt or flap can consist oE a Ele~xib1e skirt assembly, or a number of small pivotally mounted metal rocls suspende~l in the Eorm of a curtain or may consist of a number of pivotally suspended sheet metal plates.
Since it is unavoidable that there will be spaces be-tween the fuel pieces and through which ~ases of combustion and radiated heat will pass, the present invention also incorporates a thermally controlled water sprinkler 13 to extinguish any combustion which might occur in the feed tunnel. Thermal probe 13' detects the presence of combustion activating valve 13'' to sprinkle water on the fuel to extinguish the fire. Once the fire is extinguished, and the tempera-ture of probe 13' becomes reduced, valve 13'' closes. Any damping of the wood as a result of the water sprinkling is not disadvantageous but rather is to the contrary since the advancing wood fuel will become more uniformly wetted resulting in a more uniform combustion within the combustion chamber.
Dished depression 14 is provided to collect water dis-charged from sprinkler 13. The water within the depression 14 be-comes heated from the combustion chamber and is evaporated, which provides a moist atmosphere within the feed tunnel which further inhibits re-combustion.
Also of importance in obtaining optimum and continuous efficient combustion is some provision for the control of air ad-mitted into the assembly for the combustion process. As will be seen in Figure 6, the assembly is provided with a primary air inlet port 17 and a secondary air inlet port 17'. Also with respect to Figure 6, a pivotally mounted probe arm 15 is provided and which is movable from a vertical position to a raised position as shown in Figure 6 as a result of being contacted by fuel logs and slabs `~ t ~ 7~
30. The amount of air permitt~d to enter pr:imary air inlet port 17 is controlled by a damper plate 16, and both plate 16 and grate cover plate 6 are interconnected with probe arm 15 by means of linkages 15' shown schematically in Figure 6. The assembly as shown in Figure 6 is fully loaded with wood 30 and the probe arm 15 is fully elevated which fully opens damper plate 16, and grate cover plate 6 is fully withdrawn which provides maximum admission of air resulting in maximum combustion.
The secondary air inlet opening 17' and its related damper may be controlled independently from the operation of damper plate 16 and grate cover plate 6.
However, as shown in Figure 6, damper plate 16 may be pro-vided with an adjustment stop 17'' which enables precise control of the amount of air admitted for combustion. If the feed tunnel is only partially filled with fuel, grate cover plate 6 half-covers grate 5, and damper plate 16 half-covers the primary air inlet port 17 and the positioning of adjustment stop 17'' governs the degree to which the secondary air inlet port 17' can be opened, thus enabling precise air control.
If probe arm 15 is in a vertical position, this indicates the absence of fuel with the result that grate 5 is closed by cover plate 6 and primary air inlet port 17 is closed by damper plate 16 and secondary air inlet port 17' is substantially closed.
A preferred construction is illustrated in Figure 7, and in this arrangement, the combustion chamber and adjacent portion of feed tunnel 1 are formed as a unitary component. In this embodiment the feed tunnel is water cooled by means of a water jacket, and the surface 26 having the dished depression 14 therein is made of stain-less steel.
_g_ 17 ~I r~
The combustion chclmLler area o~ the assernbly silown in ~ig-ure 7 is pre-Eerably Llned wi-th ~ire bricks 13 or other equivalen-t material.
In Figure 7, the grate cover plate and adjustment plate are not shown.
The arrangement as shown in Figure 7 has several a~vant-ages. The water cooling of the feed tunnel minimizes the tempera-ture within this area of the assembly, and -this inhibits pre-ignition or pre-combustion. The fire brick lining within the combustion cham-ber promotes longevity of the complete structure.
Also as shown in Figure 7, the bottom of grate 5 is posi-tioned somewhat lower than as shown in Figure 1, and this assists in maximum combustion. In the depression formed by the lowering of grate 5, a layer of hot embers may form which are not disturbed by the advancing fuel.
Within the scope of the present invention, it is possible to replace abutment plate 4 and limit switch 12 by other suitable arrangements associated with fuel pushing plate 23. With such an alternative arrangement, increased resistance to fuel movement is sensed, and the conveyor arrangement stopped until such resistance lessens as a result of the combustion process.
With reference to Figure 1, the feed tunnel 1 could be provided with a horizontal partition such as shown by the broken lines 32. With this arrangement, independently operating conveyors will be provided, and the various means discussed above to prevent pre-ignition in the feed tunnel will be provided in each of the compartments of the feed tunnel. With the feed tunnel divided into upper and lower compartments, the conveyor in the upper portion would move at a speed slower than the conveyor in the lower portion.
In addition such a furnace must be capable of successful operation and control whether the fuel be dry, or damp, or wet, and in this regard, and when the fuel is wet or damp,environmental considerat-ions are important and the formation and discharge of smoke and other pollutants must be minimized as much as possible.
It is absolutely essential that these problems and diffi-culties be overcome if one is to satisfactorily continuously operate a wood burning assembly which is continuously fed with fuel.
The prime purpose of the present invention then is to pro-vide a wood burning furnace or assembly which avoids the inherent disadvantages of furnaces of this general type and which enables the continuous combustion of fuel in the form of slabs or long . ~ .
.
i ~ ~;47~
lengths which are Eed to a combustion chamber in continuous manner and which inhibits combus-tion or pre-igni-tion of the fuel during the travel along the feed path and before introduction into the combustion chamber.
Applicant has established through experimentation that the present assembly (depending upon the length of the feed path and the volume of fuel) provides continuous operation for up to 10 to 12 hours with only two fillings of the assembly. In the pilot furnace constructed and operated, the feed supply tunnel was approx-imately four metres long having a cross-section area of approximately .25 square metres.
During the combustion of fuel which is continuously fed to a combustion chamber, the danger of pre-ignition and combustion of the fuel prior to its introduction into the combustion chamber is always present. This is particularly true in the case of dry fuel, but the danger still exists even when the fuel is wet or damp, inasmuch as the fuel becomes dried during its travel in the feed tunnel as a result of heat radiating from the combustion chamber and the resultant heating of the completed assembly. Drying of wet or damp fuel in the feed tunnel is also increased as a result of the spaces or gaps between the pieces of wood in the feed tunnel, and which enable the circulation of warm drying air. To minimize the extent of these gaps or spaces, it is preferred that at least the bottom portion of the combustion chamber and at least an adja-cent portion of the feed tunnel being of semi-circular cross-sec-tion so that the fuel can become compacted as much as possible.
The more the fuel is compacted, the less is the danger of pre-ignition or pre-combustion and the presentation of fuel pieces in concentrated manner into the combustion chamber greatly enhances ~ .
~ 3 ~ 4 7 ~ r) the rate of combustion.
The present invention avoids the inherent disadvantages of the prior art arrangements and fully satisfies all requirements for an assembly of this type by specifically providing a wood burn-ing assembly for fuel in the form of slabs or log lengths comprising a combustion chamber with a grate and primary and secondary air inlet ports, and an ash receptacle beneath the grate, and a grate closure plate slideably mounted with respect to the grate enabling selected opening and closing thereof, and a feed tunnel opening into the combustion chamber and means within the feed tunnel to advance the fuel to the com-bustion chamber and a movable abutment plate in the combustion chamber at a position opposite to the feed tunnel, the abutment plate being interconnected with drive means for the means to advance the fuel to control rate of advance of the fuel into the combustion chamber, and means in the feed tunnel adjacent the combustion chamber to inhibit combustion of the fuel prior to its introduction into the combustion chamber.
The invention will now be more fully described with ref-erence to the accompanying drawings wherein:
Figure 1 is a side sectional view of one embodiment of the present invention;
Figure 2 is a sectional view taken along line II-II of Figure l;
Figure 3 is a sectional view taken generally along line III-III of Figure 1, illustrating a preferred embodiment;
Figure 4 is a side sectional view taken along line IV-IV
of Figure 3;
Figure 5 is a sectional view taken generally along line ~ lfi~7~1S
V-V oE Figure l;
Figure 6 is a side sectlonal view of a combust:ion chamber and adjacent portion of a feed tunnel showing the arrangement of air inlet control elements; and Figure 7 is a side sectional view oE a preE~rre(l constrwct-ion of the present inventive concept.
The accompanying drawings will now be discussed in detail and wherein like reference numerals refer to like parts.
Numeral 1 indicates a feed tunnel which opens in the area shown at 2 into a combustion chamber 9. The feed tunnel has a fill-ing door 24, and the combustion chamber has door 3 and a grate 5 be-neath which is positioned an ash receptacle 22.
A combustion gas discharge duct 21 is positioned above the combustion chamber leading into a heat exchanger 25 which may be of the air or water type. The heat exchanger 25 may be in the form of a boiler, and due to environmental considerations a smoke and poll-utant extractor may also be provided.
The feed tunnel 1 is provided with fuel advancing means which may be in the form of an endless chain conveyor 20, positioned within a safety hood 20'. The conveyor is driven by motor means (not shown) and additionally may be provided with a crank '' for filling purposes. The conveyor 20 carries conveyor plate 23 which is pivotally mounted thereon for pivoting movement only in the di-rection of arrow A as shown. The plate 23 is of a dimension which generally fills the interior of the feed tunnel. The pivoted mount-ing of the plate 23 enables the feed tunnel to be filled by insert-ing fuel through door 24 and its securement against movement in a direction opposite to arrow A enables it to advance wood fuel along the feed tunnel during continuous operation of the conveyor 20 at i ~ fi 4 7 ~1 r~
very slow speed. rrhe conveyor may be mountecl elther above the ~eed tunnel as shown or beneath it, and the aclvancing mechanism may take different forms such as a screw feed positioned in the bottom of the tunnel to advance the wood to the combustion chamber. The conveyor means continuously advances the wood at a very low rate of speed dependent upon the speed of combustion of the wood within the com-bustion chamber.
Positioned within the combustion chamber 9 opposite to the entrance of the feed tunnel is a movable abutment plate 4 which carries a rod 11 which extends exteriorly of the combustion chamber to a position adjacent a limit switch 12. The abutmen plate 4 is biased to the position shown in Figure 1 by the provision of spring 11'. Pressure against abutment plate 4 by the advancing wood pieces moves the plate against the tension of spring 11, and the wood is continuously advanced by the conveyor until such time as rod 11 con-tacts limit switch 12 which is electrically interconnected with the drive means (not shown) of the conveyor 20. Closing of the limit switch 12 by rod 11 stops the conveyor drive, and commencement of the conveyor drive occurs when the force of fuel against the abut-ment plate 4 is removed (as a result of the burning of fuel) andthe rod 11 is withdrawn from the limit switch 12 under the action of spring 11'. Interconnection between the limit switch 12 may either be electrically as described or by the use of a Bowden cable.
Figure 2 shows that the interior of the feed tunnel may be rectangular. However, and as shown in the preferred embodiment of Figure 3, at least the lower portion of the combustion chamber and the adjacent portion of the feed tunnel are of generally semi-circular cross-section. This arrangement is also shown in Figure 5, and from which it will be noted that the grate 5 is also of semi-~ -5 1 ~ ~1 7 llr ~ ~
circular configura-tlcn and that khe grate ~ArS extelld irl the d:i-rection of movement of -the fuel.
~ n a further preferred embodiment, the combustion chamber and adjacent portion of the feed tunnel are provided with guide members 10 with the dlstance between the oppositely positioned guide members decreasing in the direction of advance oE the wood fuel. The semi-circular configuration of the combustion chamber and the provision of the guide element 10 compress the wood fuel as much as possible within the combustion chamber providing for a much more concentrated combustion.
Numeral 7 generally indicates various means to inhibit pre-ignition and combustion of the fuel within the feed tunnel, these means consisting of water sprinkler 13, dished depression 14, and at least one downwardly depending flexible skirt or feely pivoted flap or flaps 26, all as clearly shown in Figure 4. These elements combine to inhibit combustion of the fuel within the tunnel in the area shown by numeral 27.
Operation of the water sprinkler 13 may suitably be con-trolled by thermal probe 13' which controls supply valve 13''. se-neath sprinkler 13 is provided a dished depression 14 which prefer-ably is provided with an inclined surface 19 to guard against the jamming of wood.
An upper covering for grate 5 is not considered to be necessary inasmuch as the covering could become blocked by small fragments of wood or bark. Due to the provision of inclined sur-face 19, any accumulated fragments are simply moved ahead by the advancing fuel into the combustion chamber.
Beneath grate 5 a movable grate closure plate 6 is pro-vided and as shown in Figure 5, the plate 6 may have semi-circular fi47~5 configurations.
Due to the constituent nature oE the wood fuel, and rela-tive degree of dryness and thickness, uniform combustion of the fuel is not possible with the result that slower burning pieces will be advanced into the combustion chamber at a speed greater than their degree of combustion, and without some control over the con-veyor operation a jam of wood within the combustion chamber could occur. Abutment plate 4 acting on limit switch 12 to stop conveyor feed for a short time avoids this difficulty. As soon as pressure against abutment plate 4 is removed due to combustion, the conveyor resumes movement.
As discussed above, the guide elements 10 compact the ad-vancing fuel as much as possible to provide a concentrated combustion mass. In addition, however, the elements 10 act to lift the lower-most pieces of the advancing fuel to a somewhat inclined direction of feed so that they can advance further into the combustion chamber before contacting abutment plate 4.
In addition to providing for a more concentrated combus-tion, the semi-circular configuration of the combustion chamber and at least an adjacent portion of the feed tunnel minimizes the spaces between the fuel pieces and this has the effect of inhibiting com-bustion of the fuel within the feed tunnel. Pre-ignition, and pre-combustion of the fuel within the feed tunnel can be minized by this arrangement but can never be completely eliminated. To further inhibit this pre-combustion, the elements 7 as discussed above are provided in the feed tunnel adjacent the combustion chamber. The skirt or flap 26 which is freely pivotally mounted lies against the upper pieces of wood and this minimizes the radi-ation of heat from the combustion chamber along the feed tunnel.
`i I ~47~ 5 This skirt or flap can consist oE a Ele~xib1e skirt assembly, or a number of small pivotally mounted metal rocls suspende~l in the Eorm of a curtain or may consist of a number of pivotally suspended sheet metal plates.
Since it is unavoidable that there will be spaces be-tween the fuel pieces and through which ~ases of combustion and radiated heat will pass, the present invention also incorporates a thermally controlled water sprinkler 13 to extinguish any combustion which might occur in the feed tunnel. Thermal probe 13' detects the presence of combustion activating valve 13'' to sprinkle water on the fuel to extinguish the fire. Once the fire is extinguished, and the tempera-ture of probe 13' becomes reduced, valve 13'' closes. Any damping of the wood as a result of the water sprinkling is not disadvantageous but rather is to the contrary since the advancing wood fuel will become more uniformly wetted resulting in a more uniform combustion within the combustion chamber.
Dished depression 14 is provided to collect water dis-charged from sprinkler 13. The water within the depression 14 be-comes heated from the combustion chamber and is evaporated, which provides a moist atmosphere within the feed tunnel which further inhibits re-combustion.
Also of importance in obtaining optimum and continuous efficient combustion is some provision for the control of air ad-mitted into the assembly for the combustion process. As will be seen in Figure 6, the assembly is provided with a primary air inlet port 17 and a secondary air inlet port 17'. Also with respect to Figure 6, a pivotally mounted probe arm 15 is provided and which is movable from a vertical position to a raised position as shown in Figure 6 as a result of being contacted by fuel logs and slabs `~ t ~ 7~
30. The amount of air permitt~d to enter pr:imary air inlet port 17 is controlled by a damper plate 16, and both plate 16 and grate cover plate 6 are interconnected with probe arm 15 by means of linkages 15' shown schematically in Figure 6. The assembly as shown in Figure 6 is fully loaded with wood 30 and the probe arm 15 is fully elevated which fully opens damper plate 16, and grate cover plate 6 is fully withdrawn which provides maximum admission of air resulting in maximum combustion.
The secondary air inlet opening 17' and its related damper may be controlled independently from the operation of damper plate 16 and grate cover plate 6.
However, as shown in Figure 6, damper plate 16 may be pro-vided with an adjustment stop 17'' which enables precise control of the amount of air admitted for combustion. If the feed tunnel is only partially filled with fuel, grate cover plate 6 half-covers grate 5, and damper plate 16 half-covers the primary air inlet port 17 and the positioning of adjustment stop 17'' governs the degree to which the secondary air inlet port 17' can be opened, thus enabling precise air control.
If probe arm 15 is in a vertical position, this indicates the absence of fuel with the result that grate 5 is closed by cover plate 6 and primary air inlet port 17 is closed by damper plate 16 and secondary air inlet port 17' is substantially closed.
A preferred construction is illustrated in Figure 7, and in this arrangement, the combustion chamber and adjacent portion of feed tunnel 1 are formed as a unitary component. In this embodiment the feed tunnel is water cooled by means of a water jacket, and the surface 26 having the dished depression 14 therein is made of stain-less steel.
_g_ 17 ~I r~
The combustion chclmLler area o~ the assernbly silown in ~ig-ure 7 is pre-Eerably Llned wi-th ~ire bricks 13 or other equivalen-t material.
In Figure 7, the grate cover plate and adjustment plate are not shown.
The arrangement as shown in Figure 7 has several a~vant-ages. The water cooling of the feed tunnel minimizes the tempera-ture within this area of the assembly, and -this inhibits pre-ignition or pre-combustion. The fire brick lining within the combustion cham-ber promotes longevity of the complete structure.
Also as shown in Figure 7, the bottom of grate 5 is posi-tioned somewhat lower than as shown in Figure 1, and this assists in maximum combustion. In the depression formed by the lowering of grate 5, a layer of hot embers may form which are not disturbed by the advancing fuel.
Within the scope of the present invention, it is possible to replace abutment plate 4 and limit switch 12 by other suitable arrangements associated with fuel pushing plate 23. With such an alternative arrangement, increased resistance to fuel movement is sensed, and the conveyor arrangement stopped until such resistance lessens as a result of the combustion process.
With reference to Figure 1, the feed tunnel 1 could be provided with a horizontal partition such as shown by the broken lines 32. With this arrangement, independently operating conveyors will be provided, and the various means discussed above to prevent pre-ignition in the feed tunnel will be provided in each of the compartments of the feed tunnel. With the feed tunnel divided into upper and lower compartments, the conveyor in the upper portion would move at a speed slower than the conveyor in the lower portion.
Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A wood burning assembly for fuel in the form of slabs or log lengths comprising a combustion chamber with a grate and primary and secondary air inlet ports, and an ash receptacle beneath the grate, and a grate closure plate slideably mounted with respect to the grate enabling selected opening and closing thereof, and a feed tunnel opening into the combustion chamber and means within the feed tunnel to advance the fuel to the com-bustion chamber and a movable abutment plate in the combustion chamber at a position opposite to the feed tunnel, the abutment plate being interconnected with drive means for the means to advance the fuel to control rate of advance of the fuel into the combustion chamber, and means in the feed tunnel adjacent the combustion chamber to inhibit combustion of the fuel prior to its introduction into the combustion chamber.
2. An assembly according to claim 1, including a heat exchanger having a smoke extractor.
3. An assembly according to claim 2, wherein the heat exchanger is in the form of a boiler.
4. An assembly according to claim 1, including guide elements provided in side walls of the combustion chamber, the distance between oppositely positioned guide elements decreasing in the direction of advance of the fuel.
5. An assembly according to claim 1, including a rod secured to the abutment plate and extending exteriorly of the com-bustion chamber to provide an outer end, and a limit switch posi-tioned adjacent the outer end of the rod, contact of the limit switch by the outer end of the rod stopping advance of the fuel into the combustion chamber.
6. An assembly according to claim 1, wherein the means for inhibiting combustion of the fuel includes at least one down-wardly depending flexible skirt or freely pivoted flap or flaps.
7. An assembly according to claim 1, wherein the means for inhibiting combustion of the fuel includes a thermostatically controlled water sprinkler.
8. An assembly according to claim 7 wherein a bottom portion of the feed tunnel beneath the water sprinkler is in the form of a dished depression.
9. An assembly according to claim 1, including a freely pivoted downwardly depending probe, the probe being interconnected with the grate closure plate and a damper plate associated with the secondary air inlet port.
10. An assembly according to claim 1 or 9, including an adjustable stop provided on a damper plate associated with the primary air inlet port.
11. An assembly according to claim 1, wherein a bottom portion of the feed tunnel at least in the area of the combustion chamber is of upwardly-open semi-circular cross-section.
12. An assembly according to claim 1, or wherein the grate is of upwardly-open semi-circular cross-section.
13. An assembly according to claim 1, 11 or 12, wherein the combustion chamber is lined with firebrick or other fire-proof material.
14. An assembly according to claim 8, wherein the dished depression is formed of stainless steel.
15. An assembly according to claim 1, wherein the com-bustion chamber and at least a portion of the feed tunnel having the means to inhibit combustion are formed as a unitary component.
16. An assembly according to claim 14, wherein the at least a portion of the feed tunnel is water cooled and is provided with a water cooling jacket.
17. An assembly according to claim 15 or 16, wherein the at least a portion of the feed tunnel includes the means to inhibit combustion of the wood fuel, a dished depression formed of stain-less steel being provided in a bottom portion of the feed tunnel beneath a thermostatically controlled water sprinkler.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3037075.3 | 1980-10-01 | ||
| DE19803037075 DE3037075C2 (en) | 1980-10-01 | 1980-10-01 | Fuel conveyor for a grate furnace |
| DE19813109916 DE3109916C2 (en) | 1981-03-14 | 1981-03-14 | Device for burning logs |
| DEP3109916.5 | 1981-03-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1164745A true CA1164745A (en) | 1984-04-03 |
Family
ID=25788202
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000386907A Expired CA1164745A (en) | 1980-10-01 | 1981-09-29 | Wood burning assembly |
Country Status (7)
| Country | Link |
|---|---|
| AT (1) | AT376492B (en) |
| CA (1) | CA1164745A (en) |
| FI (1) | FI813014L (en) |
| FR (1) | FR2491197A1 (en) |
| NO (1) | NO813327L (en) |
| SE (1) | SE8105722L (en) |
| YU (1) | YU230381A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2571125A1 (en) * | 1984-10-02 | 1986-04-04 | Agarra Henri | Boiler with automatic loading for domestic and industrial heating |
-
1981
- 1981-09-25 YU YU02303/81A patent/YU230381A/en unknown
- 1981-09-28 FI FI813014A patent/FI813014L/en not_active Application Discontinuation
- 1981-09-28 AT AT0414281A patent/AT376492B/en not_active IP Right Cessation
- 1981-09-29 SE SE8105722A patent/SE8105722L/en not_active Application Discontinuation
- 1981-09-29 CA CA000386907A patent/CA1164745A/en not_active Expired
- 1981-09-30 NO NO813327A patent/NO813327L/en unknown
- 1981-10-01 FR FR8118540A patent/FR2491197A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| AT376492B (en) | 1984-11-26 |
| SE8105722L (en) | 1982-04-02 |
| FI813014A7 (en) | 1982-04-02 |
| FR2491197A1 (en) | 1982-04-02 |
| FR2491197B3 (en) | 1983-07-22 |
| ATA414281A (en) | 1984-04-15 |
| NO813327L (en) | 1982-04-02 |
| FI813014L (en) | 1982-04-02 |
| YU230381A (en) | 1984-02-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20010403 |