Lek, Sock Peng (142 Shelford Road, Singapore 7, 28850, SG)
Lek, Sock Peng (142 Shelford Road, Singapore 7, 28850, SG)
| 1. | An inverted solid fuel reactor for combusting solid particulate fuel comprising a. a primary combustion chamber which includes (i) an inlet opening for the delivery of said solid particulate fuel into said primary combustion chamber to define a bulk of solid particulate fuel within said primary combustion chamber, (ii) a combustion zone opening provided through said primary combustionchamber below the inlet opening, said combustion zone opening being a constricted mouth opening to the said primary combustion chamber, said primary combustion chamber, in use holding the bulk of particulate fuel above said combustion zone opening in a stable supporting condition and to expose a downwardly directed surface of me bulk of said particulate fuel b. a conduit to deliver from external of said primary combustion chamber, a supply of oxygen to the combustion zone at said combustion zone opening from below said downwardly directed surface of the bulk of said solid particulate fuel to, in useprovide the necessary oxygen for maintaining a combustion of said solid particulate fuel at least at said downwardly directed surface, c an exhaust outlet opening in said primary combustion chamber, located above said combustion zone opening and in use, above the bulk of said solid particulate fuel. |
| 2. | An inverted solid fuel reactor as claimed in claim 1 wherein said primary combustion chamber is a silo which includes at is lower most region, said combustion zone opening and at or towards the upper most region, said exhaust outlet. |
| 3. | An inverted solid fuel reactor as claimed in claims 1 or 2 wherein said primary combustion chamber is a silo which includes at is upper most region, said inlet opening for the delivery of solid particulate fuel. |
| 4. | An inverted solid fuel reactor as claimed in any one of claims 1 to 3 wherein said primary combustion chamber includes a common opening for said exhaust outlet. and said solid particulate fuel delivery inlet. |
| 5. | An inverted solid fuel reactor as claimed in anyone of claims 1 to 4 wherein a means to feed said solid particulate fuel to said inlet opening from a location exterior of said primary combustion chamber is provided. |
| 6. | An @ inverted solid fuel reactor as claimed in claim 5 wherein said means to feed is conveyor enclosed within a delivery duct. |
| 7. | An inverted solid fuel reactor as claimed in claim 6 wherein said delivery duct has an outlet opening at said inlet to said primary combustion chamber and an inlet opening external of said primary combustion chamber positioned at an elevation, below said combustion zone opening. |
| 8. | An inverted solid fuel reactor as claimed in any one of claims 1 to 7 wherein said primary combustion chamber is located within a secondary combustion chamber which envelops about a substantial part of said primary combustion chamber and provides a cavity at least in part about said primary combustion chamber. |
| 9. | An inverted solid fuel reactor as claimed in claim 8 wherein said secondary combustion chamber provides a said cavity for the thereby entrained gasses exhausting said primary combustion chamber from said exhaust outlet to pass towards said combustion zone opening. |
| 10. | An inverted solid fuel reactor as claimed in claims 8 or 9 wherein said cavity is an annular cavity. |
| 11. | An inverted solid fuel reactor as claimed in any one of claims 8 to 10 wherein said secondary combustion chamber provides an envelope to said primary combustion chamber save for at least one opening provided in the said secondary combustion chamber provided at or proximate to said combustion zone opening. |
| 12. | An inverted solid fuel reactor as claimed in any one of claims 8 to 11 wherein said secondary combustion chamber provides an envelope about said primary combustion chamber save for at least one waste opening provided in the said secondary combustion chamber proximate to and below said combustion zone opening, said waste opening positioned below said combustion zone opening to allow for solid combustion byproduct (eg ash) to pass through said waste opening to be ejected from said secondary combustion chamber. |
| 13. | An inverted solid fuel reactor as claimed in any one of claims 8 to 12 wherein said secondary combustion chamber provides an envelope about primary combustion chamber save for at least one waste opening provided in the said secondary combustion chamber proximate to and below said combustion zone opening and through which said waste opening said conduit for delivery of oxygen passes. |
| 14. | An inverted solid fuel reactor as claimed in claim 8 wherein said secondary <BR> <BR> <BR> <BR> combustion chamber provides an envelope about primary combustion chamber save for a waste opening at its lower most region, proximate to and below said combustion zone opening. |
| 15. | An inverted solid fuel reactor as claimed in any one of claims 8 to 14 wherein a casing is provided about said secondary combustion chamber to provide and envelope about said secondary combustion chamber yet defining a containment region therebetween for gasses passing from said secondary combustion chamber via at least its said waste opening, said casing being of an insulative material and including an exhaust opening for the escape of gasses from said reactor. |
| 16. | Asz inverted solid fuel reactor as claimed in claim 15 wherein said casing provides a catchment region for the collection of said ash passing through said waste opening of said secondary combustion chamber. |
| 17. | An inverted solid fuel reactor as claimed in claims 16 wherein said catchment region is vertically below said waste opening of said secondary combustion chamber. |
| 18. | An inverted solid fuel reactor as claimed in claims 16 or 17 wherein said catchment region is a non horizontal surface. |
| 19. | An inverted solid fuel reactor as claimed in any one of claims 16 to 18 wherein a waste removal opening is provided to said casing at a lower region thereof to allow in use, the transfer there thorough of said ash collected at said catchment region. |
| 20. | An inverted solid fuel reactor as claimed in any one of claims 14 to 19 wherein said casing provides its exhaust opening at a region above said primary and secondary combustion chambers. |
| 21. | All inverted solid fuel reactor as claimed in any one of claims 14 to 19 wherein said casing provides its exhaust opening at or towards an upper region of the containment region of said casing. |
| 22. | An inverted solid fuel reactor as claimed in any one of claims 14 to 21 wherein . said conduit for delivery of oxygen delivers oxygen from external of said casing. |
| 23. | An inverted solid fuel reactor as claimed in any one of claims 14 to 22 wherein said duct for delivery of solid particulate fuel provides its inlet opening external of said casing. |
| 24. | An inverted solid fuel reactor as claimed in any one of claims 14 to 23 wherein secondary combustion chamber includes at least one outlet opening at a region thereof above said primary combustion zone via which gasses within said cavity between said secondary combustion chamber and said primary combustion chamber can be extracted to external of said casing via an extraction conduit. |
| 25. | An inverted solid fuel reactor as claimed in any one of claims 1 to 24 wherein the primary combustion chamber includes at least one side wall surface defining a side enclosure to said chamber and a lower wall surface extending inwardly from the side wall surfaces towards said combustion zone opening, said combustion zone opening provided through said bottom wall surface away from said side walls. |
| 26. | An inverted solid fuel reactor as claimed in claim 25 wherein said lower wall is a sloping wall sloping downwardly towards said combustion zone opening. |
| 27. | An inverted solid fuel reactor as claimed inclaim 25 or 2. 6 wherein by the provision of said combustion zone opening away from said side wall, a constricted mouth opening configuration of said combustion zone opening is provided. |
| 28. | An inverted solid fuel reactor as claimed in any one of claims 1 to 24 wherein said primary combustion chamber includes a side wall surface tapering towards the bottom and towards said combustion zone opening in a manner such that said combustion zone opening is provided at the end of said taper and is of a size smaller than the maximum width (diameter) of the primary combustion chamber. |
| 29. | A method of combusting solid particulate fuel in an inverted solid fuel reactor which comprises (a) a primary combustion chamber which includes (i) an inlet opening for the delivery of said solid particulate fuel into said primary combustion chamber to define a bulk of solid particulate fuel within said primary combustion chamber, (ii) a combustion zone opening provided through said primary combustion chamber below the inlet opening, said combustion zone opening being a constricted mouth opening to the said primary combustion chamber, said primary combustion chamber, in use holding the bulk of particulate fuel above said combustion zone opening in a stable supporting condition and to expose a downwardly directed surface of the bulk of said particulate fuel, (b) a conduit to deliver from external of said primary combustion chamber, a supply of oxygen to the combustion zone at said combustion zone opening from below said downwardly directed surface of the bulk of said solid particulate fuel to, in use provide the necessary oxygen for maintaining a combustion of said solid particulate fuel at least at said downwardly directed surface, (c) an exhaust outlet opening in said primary combustion chamber, located above said combustion zone opening and in use, above the bulk of said solid particulate fuel said method comprising, a. providing a combustible cover to said combustion zone opening, b. loading said solid particulate fuel into said primary combustion chamber via said inlet opening to become supported in part by said combustible cover and to hold said bulk of said solid particulate fuel within said primary combustion chamber c. delivering via said conduit a supply of oxygen to said combustible cover intermediate of said conduit and said bulk to encourage the combustion of said downwardly directed surface of said bulk and to combust said cover to expose said downwardly directed surface to said supply of oxygen. |
| 30. | A method as claimed in claim 29 wherein said solid particulate fuel is in at least in part in a combusting phase during its said loading into said primary combustion chamber. |
BACKGROUND The burning of waste or off fall material or materials specifically designated for the purposes of burning to generate heat energy therefrom and to thereby use such heat energy for particular purposes is well known. Many incinerators use the combustion of material within a furnace for the purposes of providing heating which may be utilised directly for space heating or for the purposes of elevating water temperature for the purposes of steam turbines or other applications. Known devices have for example been described m prior patent specificationsTsuch as those of US4413571, US4384535, W088/00230, W002/084174, WO01/86208. Indeed most of these prior publications have also recognised the advantage that is generated from subjecting a mass of combustible material to a combustion environment at the lower regions of such a mass. With heat rising through the mass of combustible fuel a gasifying of part of the fuel will occur and such gasification will include combustible gas which can be separately combusted.
The disadvantages of the prior publications as mentioned above are as follows: US4384535 requires during its operation for air to be forced into the bed of the solid fuel thereby causing the volume of air to be combusted with different Riels.
Furthermore ash will fly around above the fuel due to the injection of air and rising heat. It is anticipated that the efficiency may be low as a result of the heat loss from the apparatus due to its size and due to the amount of fuel that can be fed.
W002/084174 requires the injection of primary and secondary air into the primary and secondary combustion zones. The injection of air will blow away heat from the fuel thereby slowing the reaction of the fuel. Furthermore WO02/084174 describes the need for a feeding of the fuel in batches.
W08 8/00230 is of a fumace design which may allow for the escape of volatile gases without such gases reacting with the oxygen. The ash may also not be subjected to full combustion. Air has to be forced into the bed of the solid. fuel thereby causing the volume of air to be combusted with different fuels. Too much injection of air will lower the heat from the fuel and the furnace.
EP0532901 is of a furnace wherein reacted gases are channelled back to the furnace and thereby reduce the efficiency of the reaction. The configuration of the mmace is such that ash will also be flying around in the silo as the heat rises.
US510174 is also of a design where ash will fly around above the fuel due to the injection of air and rising heat. Fuel may not be fully combusted due to the fluidised bed that pushes the fuel to the outlet.
WOO 1/86208 would also have issues with ash flying around above the fuel due. to injection of air and rising heat. Its sufficiency may also not be high because of the heat loss from the apparatus due to its size and to the amount of fuel that can be fed.
Furthermore an ash discharge is absent.
Whilst the prior publications mentioned above are of a similar character in that they are inverted furnaces, it is an object of the present invention to provide a solid fuel reactor which will overcome at least some of the above disadvantages or to at least provide the public with a useful choice.
BRIEF DESCRIPTION OF THE INVENTION Accordingly in a first aspect the present invention consists in an inverted solid fuel reactor for combustmg solid particulate fuel comprising a. a primary combustion chamber which includes an inlet opening for the delivery of said solid particulate fuel into said primary combustion chamber to define a bulk of solid particulate fuel within said primary
combustion chamber, a combustion zone opening provided below the inlet opening, said combustion zone opening being of a constricted mouth opening to the said primary combustion chamber, said primary combustion chamber, in use holding the bulk of particulate fuel above said combustion zone opening in a stable supporting condition and to expose a downwardly directed surface of the bulk of said particulate fuel b. a conduit to deliver from external of said primary combustion chamber, a supply of oxygen to me combustion zone at said combustion zone opening from below said downwardly directed surface of the bulk of said solid particulate fuel to, in use provide the necessary oxygen for maintaining a combustion of said solid particulate fuel at least at said downwardly directed surface. c. an exhaust outlet opening in said primary combustion chamber, located above said combustion zone opening and above, in use the bulk of said solid particulate fuel.
Preferably said primary combustion chamber is a silo which includes at is lower most region, said combustion zone opening and at or towards the upper most region, said exhaust outlet.
Preferably. said primary combustion chamber is a silo which includes at is upper most region, said inlet opening for the delivery of solid particulate fuel.
Preferably said primary combustion chamber includes a common opening for said exhaust outlet and said solid particulate fuel delivery inlet.
Preferably a means to feed said solid particulate mel to said inlet opening from a location exterior of said primary combustion chamber is provided.
Preferably said means to feed is conveyor enclosed within a delivery duct.
Preferably said delivery duct has an outlet opening at said inlet to said primary combustion chamber and an inlet opening external of said primary combustion chamber positioned at a elevation, below said combustion zone opening.
Preferably said primary combustion chamber is located within a secondary combustion chamber which envelops about a substantial part of said primary combustion chamber and provides a cavity thereabout.
Preferably said secondary combustion chamber provides a said cavity to allow gasses exhausting said primary combustion chamber from said exhaust outlet to pass towards said combustion zone opening.
Preferably said cavity is an annular cavity.
Preferably said secondary combustion chamber provides an envelope to said primary combustion chamber save for at least one opening provided in the said secondary combustion chamber provided at or proximate to said combustion zone opening.
Preferably said secondary combustion chamber provides an envelope about primary combustion chamber save for at least one opening provided in the said secondary combustion chamber proximate to and below said combustion zone opening, said opening positioned below said combustion zone opening to allow for solid combustion by-product (eg ash) to pass through said opening to be ejected from said secondary combustion chamber.
Preferably said secondary combustion chamber provides an envelope about primary combustion chamber save for at least one opening provided in the said secondary combustion chamber proximate to and below said combustion zone opening and through which said opening said conduit for delivery of oxygen passes : Preferably said secondary combustion chamber. provides an envelope about primary combustion chamber save for at being opening at its lower most region, proximate to and below said combustion zone opening.
Preferably a casing is provided about said secondary combustion chamber to provide and envelope about said secondary combustion chamber to define containment to gasses passing from said secondary combustion chamber via at least its said opening, said casing being of an insulative material and including an exhaust opening for the escape of gasses from said reactor.
Preferably said casing provides a. catchment region for the collection of said ash passing though said opening of said secondary combustion chamber.
Preferably said catchment region is vertically below said opening of said secondary combustion chamber.
Preferably said catchment region is a non horizontal surface.
Preferably an opening is provided to said casing at a lower region thereof to allow in use, the transfer there thorough of said ash collected at said catchment region Preferably said casing provides its exhaust opening at a region above said primary and secondary combustion chambers.
Preferably said conduit for delivery of oxygen delivers oxygen from external of said casing.
Preferably said duct for delivery of solid particulate fuel provides its inlet opening external of said casing.
Preferably secondary combustion chamber includes at least one outlet opening at a region thereof above said primary combustion zone via which gasses within said cavity between said secondary combustion chamber and said primary combustion chamber can be extracted to external of said casing via an extraction conduit In a further aspect the present invention consists in a method of combusting solid particulate fuel in an inverted solid fuel reactor which comprises (a) a primary combustion chamber which includes (i) an inlet opening for the delivery of said solid particulate fuel into said primary combustion chamber to define a bulk of solid particulate fuel within said primary combustion chamber, (ii) a combustion zone opening provided through said primary combustion chamber below the inlet opening, said combustion zone opening being a constricted mourn opening to the said primary combustion chamber, said primary combustion chamber, in use holding the bulk of particulate fuel above said combustion zone opening in a stable supporting condition and to expose a downwardly directed surface of the bulk of said particulate fuel, (b) a conduit to deliver from external of said primary combustion chamber, a supply of oxygen to the combustion zone at said combustion zone opening from below said downwardly directed surface of the bulk of said solid particulate fuel to, in use provide
the necessary oxygen for maintaining a combustion of said solid particulate fuel at least at said downwardly directed surface, (c) an exhaust outlet opening in said primary combustion chamber, located above said combustion zone opening and in use, above the bulk of said solid particulate fuel said method comprising, a. providing a combustible cover to said combustion zone opening, b. loading said solid particulate fuel into said primary combustion chamber via said ir opening to become supported in part by said combustible cover and to hold said bulk of said solid particulate fuel within said primary combustion chamber c. delivering via said conduit a supply of oxygen to said combustible cover intermediate of said conduit and said bulk to encourage the combustion of said downwardly directed surface of said bulk and to combust said cover to expose said downwardly directed surface to said supply of oxygen.
Preferably said solid particulate fuel is in at least in part in a combusting phase during its said loading into said primary combustion chamber.
This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. For the purposes of illustrating the invention, there is shown in the drawings a form which is presently preferred. It is being understood however that this invention is not limited to the precise arrangements shown.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view through a reactor of the present invention showing generally the preferred embodiments of the components of the reactor,
Figure 2 is a view of the reactor of Figure 1 showing in addition, the solid material flow path, Figure 3 is a view of the reactor of Figure 1 and wherein the predominant gas flow paths are indicated, Figure 4 is a view of the reactor of Figure 1 wherein in addition the predominant or likely relative pressures have been indicated and temperature information is provided, Figure 5 is a view of the reactor of Figure 1 showing solid material flow paths and wherein additional solid material extraction means have been shown, and Figure 6 shows a plurality of primary and secondary combustion zones within a single casing.
DETAILED DESCRIPTION OF THE INVENTION With reference to Figures 1 and 2, the present invention provides a reactor 1 which is able to receive from external thereof a feed of combustible material 2. The combustible material 2 during combustion and/or conversion is supported in a manner to allow for a lower region of the mass of combustible material collected in a combustion region to be exposed to a means to encourage the combustion/conversion of the combustible material at such a lower region. Where reference herein is made to "combustion"it is to be considered that it may also refer to"conversion"where the combustible material may not be directly exposed to flame but still converts some of the contents of the material into gas.
In me most preferred form such is achieved by the reactor as for example shown in Figures 1 and 2. The reactor of the present invention defines a primary combustion material containment region 3 which is preferably defined by a hopper or silo 4 which has a combustion material inlet 5, hopper walls 6 which preferably extend in a vertical direction to contain the combustible material within a restricted column, and a lower opening 7 which in use'will expose a lower combustion region of the mass of combustible material 2. The-lower opening 7 may be formed as a constriction to the column defined, by the walls 6 of the hopper 4 and such restriction will have an effect
on the size of the lower combustion region of the mass of combustible material 2. In the most preferred form the hopper provides a combustible material inlet 5 at the top of the hopper 4 although it is envisaged that the inlet may not necessarily be at the uppermost region of the hopper. The opening 5 in. the most preferred form serves the dual purpose of allowing for the displacement of combustible material into the hopper as well as providing an outlet for heated gases rising through the mass of combustible material in an upward direction through the hopper. However tulle inlet for the addition of combustible material to the hopper may be separate from the outlet of the hot combustion gases exiting the hopper or silo after having passed through the mass of combustible material 2. The passing of hot gasses through the bulk will also extract some combustible gasses from the bulk not directly exposed to the combustion zone.
At the lower opening 7 of the hopper 4 there is provided a means to encourage combustion 8 which is preferably of a means which may include for example a reactor or an oxygen supply nozzle. In the most preferred form the means is a nozzle for delivering oxygen to the combustion region of the mass of combustible material 2. As shown in Figure 1 a conduit 9 is provided to deliver from. external of the reactor 1, a supply of oxygen which may come in the form of air or pure oxygen. The conduit 9 will deliver such a gas (whether it be air or otherwise) to the nozzle 8 which will supply one of the necessary elements for ensuring that combustion at the lower region of the mass of combustible material 2 is maintained as desired. The flow rate of gas via the conduit 9 may need to be adjusted to suit and a positive delivery means such as for example a fan or air pump may be utilised for such purposes.
The nozzle outlet 11 is positioned to direct the flow of gas through the conduit 9 to impinge onto the lower surface of the mass of combustible material 2 to direct the flow of gas discharge from the nozzle into the combusting material. Some of the gases discharged from the nozzle via the outlet 11 will be encouraged to travel through the matrix of the mass of combustible material 2.
With reference to Figure 3 such a general upward flow is indicated by arrows 20. Some of the gas discharged from the nozzle 11 will also travel downwardly and towards the lower opening and perhaps out of the lower opening 7 of the hopper 4.
With reference to Figure 3, it can be seen that in such a manner an intense heat zone 21 is generated. Such a heat zone may lurthermore be a zone where combustion of both solid combustible materials 2 is occurring as well as any of the combustible gases which are being generated from the heating of such combustible material.
Accordingly a flame zone may be generally indicated by numeral 21 as shown m Figure 3.
In addition to a region contained substantially within the hopper 4 where primary combustion is occurring, a second combustion zone is provided in and trained within a secondary combustion chamber 12. The second combustion chamber 12 is an enclosure which extends about the hopper 4 and captures within it and to a substantial degree, any of the gases which are displaced from the hopper 4 either through the upper outlet opening 5 and/or the lower outlet opening 7. With reference to Figure 3 it can be seen with reference to arrows 22 that a flow through the upper outlet opening 5 of gases passing through and/or generated from the combustible material 2 is captured within the enclosure defined by the secondary combustion chamber 12. Such gases at any point in their circulation within the secondary combustion chamber 12 may be in a combusting mode or in a non combusing mode. Such will depend on temperature, the kinds of gases involved and the temperature distribution within the secondary combustion chamber 12. Certainly as such gas is discharged through the opening 5 travel downwardly towards the lower regions of the secondary combustion chamber 12, due to difference in pressure between primary and secondary chambers they are encouraged to recirculate into or at least proximate to the primary combustion zone 21 and will there be subjected to combustion or further combustion. However in advance to reaching the primary combustion zone 21 such gas flow irom the upper opening 5 of the hopper may be il1 a combusting mode. Gases discharged from the upper opening of the hopper may include hydrogen, methane, carbon monoxide. The generation of combustible gases from the combustible material will enhance the efficiency of heat generation of the reactor 1 of the present invention as such gases may in their own right generate heat or where they are recirculated to the primary
combustion zone 21, contribute to the heat to which the solid combustible material 2 is subjected.
The secondary combustion chamber 2 substantially envelopes the hopper 4 however in order to ensure that a region for discharging of exhaust gases is provided the secondary combustion chamber 12 preferably includes exhaust gas. outlets. In the most preferred form the exhaust gas outlet or outlets are provided at the lower region 28 of the secondary combustion chamber 12. An exhaust gas outlet or outlets from the secondary combustion chamber 12 are preferably provided to a region thereof which is below the primary combustion zone and preferably below the hopper 4 in order to prevent any of the non combusted gases flowing through the opening 5 of the hopper 4 from being discharged without having had the opportunity to being subjected to combustion to extract heat energy therefrom. Accordingly the secondary combustion chamber 12 has such outlets 29 provided through the perimeter wall of the secondary combustion chamber 12 below the primary combustion zone 21 and hence preferably also below the lower opening 7 of the hopper 4. With reference to Figure 3 flow of gas (preferably completely combusted gas such as carbon dioxide and nitrogen) can exit through such openings and is generally indicated by arrows 31. Whilst a further outlet opening may be provided at the end of the combustion material delivery means 32 which may for example be a belt conveyor or screw conveyor of any other suitable solid material transfer means, it is in the most preferred form that such a delivery conduit with its opening to deliver material into the hopper, has its inlet opening 33 at a region which is preferably below its outlet opening 35. The inlet opening 33 is preferably also below the primary combustion zone and preferably below the outlet 28 of the secondary combustion chamber 12.
In order to utilise the heat of the gases that are discharged from the secondary combustion chamber 12, the secondary combustion chamber 12 is preferably also enclosed to a substantial degree by a casing 38. The casing 38 is preferably a thermally insulative casing and may be made of a thermal insulation material or materials such as for example a concrete lined with a fibrous thermal cladding or any other suitable construction which can withstand the heat generated from the
combustion regions yet ensure that such heat is captured within the casing 38. The casing 38 encloses the hopper 4 and secondary combustion chamber 12 save for an outlet 39 which is preferably provided at or towards an upper region of the casing 38.
The outlet 39 allows for the gases to be delivered to be utilised for any desired purpose_ The outlet is preferably provided at the upper regions of the casing 38 since the gases discharged from the lower openings 29 of the secondary combustion chamber 12 are hot and accordingly will have a tendency to rise. Accordingly natural convection of heated gases discharged from the secondary chamber 12 will flow upwardly and be encouraged to flow outward of the casing 38 via the outlet 39. An extraction fan may also be utilised in or with reference to the outlet opening 39 to encourage the drawing of gases from me casing 38. The gases discharged through the outlet opening 39 may be utilised for such purposes as heating water or generating steam for such purposes as central heating, steam turbine power generation, or any other application which may utilise hot gas for the provision of energy. Whilst the casing 38 is preferably of a highly insulative constnuctiou, the perimeter wall of the secondary combustion chamber 12 need not be of such a construction. With reference to Figure 4, it can be seen that any heat of or generated by the gases within the secondary combustion chamber 12 can conveniently be utilised by transmission from the secondary. combustion chamber to provide additional heat to the gases which are contained within the casing 38 and exterior of the secondary combustion chamber 12.
Accordingly thermal insulation provided by the secondary combustion chamber 12 is not critical. Heat loss from the secondary combustion chamber to the region contained by the casing 38 and exterior of the secondary combustion chamber is of no significant loss to the efficiency of the invention.
Whilst brief reference has herein already been made to the flow of solid material for the supply of the combustible material to the hopper 4, the resultant product of combustion also needs to be dealt with by the present invention. The subjection of the wood chip to heat will firstly convert the wood chip into carbon.
Certainly dependent on heat but for example, it may take approximately 30 minutes to convert the wood into a carbon form thereof. During such conversion combustible
gases will be emitted from the wood chip material the utilisation of which has, ah-cady herein been described. The further subjection of the carbon to heat may then convert the carbon into ash and such may for example take 120 minutes.
The conversion of the wood chip to carbon particularly in the primary combustion zone and where such is presented as the lowermost surface of the mass of combustible material 2, the mass of combustible material will establish a self supporting condition. With reference to Figure 2 for example the lower surface 40 of the mass of combustible material 2 is when the process has advanced to a significant stage of combustion. A transformation of the wood chip particles into a carbon state.
In such a carbon state the wood chip particles will have merged and become interconnected with each other to thereby effectively define a substantially continuous 'although perhaps slightly porous lower surface of the mass 2. A constricted mouth opening of the lower opening 7 of the hopper will in addition to the conversion of the wood chip to carbon and its resultant amalgamation, aid in the support of the combustible material mass 2 despite a large proportion of the downwardly directed surface of the mass being exposed to the opening 7 and not in a vertical support with any support structure. During combustion of the carbon the carbon will be converted to ash and it is predominantly then that the then combusted solid material is ejected from the mass of combustible material 2. Such material that is ejected will be predominantly ash although some carbon may be present. The ash and/or carbon will then dispense through the lower opening 7 of the hopper 4 and through 29. Any such ash may also fall through the nozzle 8 and out through the outlet opening 10. Whilst ill the preferred form only one outlet nozzle 11 is shown, a plurality of nozzles may be provided and each need not be directed in the same direction. It may be that a plurality of nozzles are positioned to direct the flow of air in radial directions.
With reference to Figure 2 the arrows 45 show the general flow path of ash falling from the lower surface 40 of the mass of combustible material 2. Such ash may be dispensed from the lower region 28 of the secondary combustion chamber 12 via the openings 29. In the most preferred form the lower region 28 of the secondary combustion chamber 12 is provided in the form of a grate which provides a significant
plurality of openW gs theretluough which will allow for the passage of gas as defined generally by arrows 31 in Figure 3 as well as the dispensing of ash to a collection region 46 which may for example be on an upwardly facing surface of the casing 38.
The lower surface 47 of the casing 38 is preferably provided with a slope which will encourage the ash that is collected ill the collection region-47 to migrate towards an ash dispensing outlet 48. The ash dispensing outlet 48 may be of a nature which may allow for a device to be utilised for the extraction of ash. Such a device may for example be a rake or the like. Alternatively the collection region 46 may have an underlying sheet material which can be periodically extracted through the opening 48 to thereby take with it the ash collected.
The secondary combustion chamber may be made from example a mild steel.
The hopper may be made from a material such as a mild steel. As can be seen in Figure 1, the hopper is preferably supported by a support structure 50 which itself may take support from the casing 38.
During start up of the reactor of the present invention, Ln order to prevent the combustible material 2 from dispensing through the lower outlet 7, the lower outlet 7 may be covered by a grate or web or other structure which will allow for the retention of the combustible material within the region 3 prior to combustion being proceeded with. Such a grate may itself be made of a combustible material which once combustion is commenced, can also be consumed. Alternatively during start up, it may be acceptable for some of the combustible materials to pass through the lower opening 7 and become supported and pile up on the lower region 28 of the secondary combustion chamber 12. During start up of combustion the heat generated in the primary combustion zone will thereby establish the lower surface 40 of the mass of combustible material 2 and may in addition also subject the piled up combustible material to a combustion action to thereby consume such in the secondary combustion chamber.
With reference to Figure 5, a supplementary outlet 55 to the hopper 4 may be provided. Such an outlet may be a ducted outlet provided by a ducting 56. The supplementary outlet opening 55 may be utilised for the removal of partially
combustible material 2 from the hopper. Such partially combusted material preferably in the form of carbon can be extracted fio n the primary combustion zone as and when desired. As carbon has other uses and applications, it may be desirable for the device of the present invention to allow for the selective extraction of carbon therefrom.
Means to encourage the separation of the carbon from within the hopper 4 can be provided The ducting 56 preferably prevents the discharge of hot gases from the primary and/or secondary combustion chambers and such may occur by allowing the build up of carbon in a U shaped section 57 of the conduit 56. In order to allow for further extraction of heat from such carbon which will be of a temperature elevated to the ambient environment a sleeve 58 may be provided through which water can be circulated to allow for such water to be elevated in temperature from the heat exchange from the carbon within the U shaped section of the conduit.
Whilst with reference to Figure 4 a fan 88 is shown which can force air into the combustion region, alternatively the configuration may be such that air is sucked into the primary combustion zone due to convection currents and a venturi like suction being established.
With reference to Figure 5, there is shown two conduits 83 and 84. These conduits are provided preferably at or towards the top of the secondary combustion chamber 12 and towards the bottom of the secondary combustion chamber 12 respectively. The conduits are designed to allow for an extraction of gases to occur from the secondary combustion zone. In particular the conduit 83 may be utilised for extracting uncombusted or substantially uncombusted gases from near the upper regions of the secondary combustion zone. Pressure gauges 93 and 94 may be provided on such outlet conduits for the purposes of deten-nining the pressure of the gas within the secondary chamber at the points where the conduits are engaged with the secondary chamber. Whilst some of the gases extracted from the secondary combustion chamber may be fully combusted some non combusted gases useful for other applications or for further refinement may be capable of being extracted by the conduits 83 and 84. The use of the pressure gauges may allow for the determination of
the gas pressure which may correlate with the suitable opportunity for extracting the desirable gas from the secondary chamber.
With reference to Figure 6, it can be seen that a plurality of primary and secondary combustion chambers may be provided within a single casing 38. Each primary and secondary combustion chamber may be provided with its independent feed of combustible material via a delivery conduit 32
Next Patent: METHOD AND DEVICE FOR THERMAL EXHAUST GAS PURIFICATION