WO2018117864A1

WO2018117864A1 - A gasifier including a rotation apparatus and a grate

Info

Publication number: WO2018117864A1
Application number: PCT/NZ2017/050162
Authority: WO
Inventors: Laurence Brown; Michael Kramer; Graham SINGLETON; Richard UPPERTON
Original assignee: Pfs Technology Limited
Priority date: 2016-12-20
Filing date: 2017-12-13
Publication date: 2018-06-28

Abstract

A gasifier and gasification plant including at least one gasifier is disclosed. The gasifier includes a vessel having a gasification chamber with a feedstock inlet. A rotation apparatus is located within the gasification chamber between an upper portion of the gasification chamber and a lower portion of the gasification chamber, and configured to rotate about a vertical axis. The rotation apparatus includes a body, and at least one gas port in a side of the body providing a fluid pathway between the upper and lower portions of the gasification chamber. A grate is positioned between the upper and lower portions of the gasification chamber, including at least one residue port below the at least one gas port of the rotation apparatus.

Description

A GASIFIER INCLUDING A ROTATION APPARATUS AND A GRATE

STATEMENT OF CORRESPONDING APPLICATIONS

[001] This application is based on the provisional specification filed in relation to New Zealand Patent Application No. 727347, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

[002] The present disclosure relates to a gasifier.

BACKGROUND

[003] Gasification is a process converting carbonaceous feedstock with air and water into a fuel gas mixture consisting primarily of hydrogen, carbon monoxide, and carbon dioxide (known as synthesis gas or "syngas"), and residue.

[004] Various types of gasifier have been developed for carrying out the gasification process.

[005] Further, known gasifier configurations are susceptible to the formation of bridges or channels (also known as "rat holes") in the feedstock, thereby forming low pressure drop short-cuts instead of flowing through the fuel bed which result in the promotion of combustion in the channel and consequent less efficient gas production and possibly increased rates of tar production.

[006] It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

[007] Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

SUMMARY OF THE DISCLOSURE

[008] According to one aspect of the present disclosure there is provided a gasifier, including: a vessel having a gasification chamber with a feedstock inlet;

a rotation apparatus located within the gasification chamber between an upper portion of the gasification chamber and a lower portion of the gasification chamber and configured to rotate about a vertical axis, the rotation apparatus including:

a body; and

at least one gas port in a side of the body, providing a fluid pathway between the upper and lower portions of the gasification chamber;

a grate positioned between the upper and lower portions of the gasification chamber, including at least one residue port below the at least one gas port of the rotation apparatus. [009] In use, feedstock may be introduced into the upper portion of the gasification chamber, in which the gasification processes (drying, pyrolysis, combustion or oxidation, and reduction) occur. Exemplary embodiments of the gasifier of the present disclosure may be generally understood as having a downdraft configuration, in that the air is converted to gas as it flows down through the fuel bed of feedstock, and fresh feedstock is introduced into the top of the gasifier. Air flows through the fuel in the gasification chamber in the direction of the sinking feedstock as it is reacted. The drying zone is above the pyrolysis zone, which lies above the combustion zone. Heat generated in the combustion zone rises primarily through thermal conduction in the feedstock to supply heat to the pyrolysis and heating zone above. Some of the hydrogen formed in the drying zone reacts with the carbon in the feedstock and oxygen present to form hydrocarbon compounds, ranging from Methane gas (CH4) to longer carbon chain liquids called distillates and still longer carbon chain molecules such as tar.

[010] The resulting syngas passes through the gas port into the lower portion of the gasification chamber, where it may be extracted through a gas outlet - for example using an extraction device such as a fan. The feedstock residue, whether ash or char, passes through the residue port of the grate into the lower portion of the gasification chamber, where it may be extracted.

[011] In an exemplary embodiment, the gasifier may be designed to control the processes in the gasifier in such a way as to balance the atoms, heat and residence time to optimize the production of syngas and minimize the production of residues and heat.

[012] In an exemplary embodiment, the vessel may include a substantially cylindrical upper portion and a tapered lower portion. In an exemplary embodiment, the vessel may include an outer cylindrical portion connected to the tapered lower portion and overlapping the cylindrical upper portion.

[013] In use, feedstock may be introduced to the gasification chamber through the feedstock inlet. In an exemplary embodiment, the feedstock inlet may be provided at or near the top of the gasification chamber. In an exemplary embodiment, the feedstock inlet may be provided at the top of the gasification chamber, near or at its centre.

[014] In an exemplary embodiment, the feedstock inlet may be opened and closed from atmosphere. In an exemplary embodiment, the gasifier may include a feedstock inlet closing device. In an exemplary embodiment, the feedstock inlet closing device may include a plug configured to be moved between a position away from the feedstock inlet and a position seated in the feedstock inlet. In alternate exemplary embodiments, the feedstock inlet closing device may include an actuated door or hatch. In alternate exemplary embodiments, the feedstock inlet closing device may include an auger or rotary valve that provides an air seal while metering the feedstock into the gasifier.

[015] In an exemplary embodiment, the plug may be tapered, with a wider portion of the plug below a narrower portion of the plug. In an exemplary embodiment, the plug may be conical. In an exemplary embodiment, the plug may be lowered into the gasification chamber to open the feedstock inlet, and raised to close the feedstock inlet. It is envisaged that the tapered shape of the plug may assist with distribution of feedstock about the chamber, with the feedstock falling onto the tip of the plug and directed outwardly about the plug.

[016] In an exemplary embodiment, the gasifier may include at least one gas inlet in the upper portion of the gasification chamber. The at least one gas inlet may be provided for the supply of gas to the upper portion of the gasification chamber, for example one or more of: an oxidant (for example gaseous oxygen, oxygen-enriched air, or air), and a catalyst (for example, syngas). In an exemplary embodiment, syngas supplied through the at least one gas inlet may be that produced by the gasifier.

[017] In an exemplary embodiment, the at least one gas inlet may include at least one gas inlet for the supply of a first type of gas, and at least one gas inlet for the supply of a second type of gas. For example, at least one gas inlet may supply an oxidant, and at least one gas inlet may supply syngas.

[018] In an exemplary embodiment, the at least one gas inlet may include at least one first gas inlet in the upper portion of the gasification chamber, and at least one second gas inlet below the at least one first gas inlet in the upper portion of the gasification chamber. In an exemplary embodiment, the at least one first gas inlet may be provided at a pyrolysis zone, and the at least one second gas inlet may be provided at a combustion zone.

[019] In an exemplary embodiment, the supply of gas through the first and second gas inlets may be controlled separately, for example the flow rate or composition - i.e. the gas supply provided through the at least one first gas inlet is controlled independently from the gas supply provided through the at least one second gas inlet. In an exemplary embodiment, the gasifier may include a plurality of gas inlets disposed around the upper portion of the gasification chamber. In an exemplary embodiment, the at least one first gas inlet may include a plurality of first gas inlets disposed around the upper portion of the gasification chamber, and the at least one second gas inlet may include a plurality of second gas inlets disposed around the upper portion of the gasification chamber.

[020] In an exemplary embodiment, the gasifier may include a manifold connected to the plurality of gas inlets disposed around the upper portion of the gasification chamber. In an exemplary embodiment, each of the gas inlets may be connected to the manifold by a branch conduit having a thermal expansion joint. For example, the branch conduit may include a bellows. [021] According to one aspect of the present disclosure there is provided a manifold, including: a manifold conduit for extending around a vessel of a gasifier;

a plurality of branch conduits disposed radially about the manifold conduit, each branch conduit including a thermal expansion joint and extending inwardly for connection to gas inlets in fluid communication with a gasification chamber of the vessel.

[022] In an exemplary embodiment, the manifold may encircle the vessel of the gasifier, providing a continuous conduit about the vessel. In an alternate exemplary embodiment, the manifold may not extend about the entirety of the vessel.

[023] According to one aspect of the present disclosure there is provided a rotation apparatus for positioning within a gasification chamber of a gasifier between an upper portion of the gasification chamber and a lower portion of the gasification chamber, including:

a body; and

at least one gas port in a side of the body, providing a fluid pathway between the upper and lower portions of the gasification chamber,

wherein the rotation apparatus is configured to rotate about a vertical axis.

[024] In an exemplary embodiment, the body may taper from a broad base below the at least one gas port to a nose or top point above the at least one gas port. In an exemplary embodiment, the tapered body may be conical or frustoconical. In an exemplary embodiment, the body may approximate a cone, for example a pyramid.

[025] In an exemplary embodiment, the body of the rotating apparatus may include at least one outwardly projecting stirring member. In an exemplary embodiment, the at least one stirring member may be positioned between a top of the body and the at least one gas port.

[026] In an exemplary embodiment, the gasifier may include a stirrer shaft located within the upper portion of the gasification chamber and having at least one stirring member projecting outwardly from the stirrer shaft. In an exemplary embodiment, the at least one stirring member may be a plurality of stirring members. The stirrer shaft may be driven to pass the stirring member through feedstock/fuel. In an exemplary embodiment, the stirrer shaft may be connected to, and project upwardly from, the body. In an alternate exemplary embodiment, the stirrer shaft may project downwardly from the top of the gasification chamber.

[027] In an exemplary embodiment, the at least one stirring member may be a blade. In an exemplary embodiment, the blade may be oriented such that an edge of the blade faces in the direction of rotation of the stirrer shaft.

[028] In an exemplary embodiment, the at least one stirring member may be angled upward from the stirrer shaft relative to level. In an exemplary embodiment, the stirring member may be angled upward at an angle of above 0 degrees to below 90 degrees. In an exemplary embodiment, the stirring member may be angled upward at an angle within a range of between about 5 degrees to about 45 degrees. In an exemplary embodiment, the stirring member may be angled upward at an angle within a range of between about 15 degrees to about 30 degrees. In an exemplary embodiment, the stirring member may be angled upward at an angle within a range of between about 20 degrees to about 25 degrees. It should be appreciated that this is not intended to be limiting to all exemplary embodiments, and that in alternate embodiments the at least one stirring member may extend straight out from the stirrer shaft or be angled downwardly.

[029] In an exemplary embodiment, the body may include at least one helical projection on its exterior.

[030] In an exemplary embodiment, the height of the helical projection from the exterior of the body may be within a range of about 5mm to about 60mm. In an exemplary embodiment, the height of the helical projection may be within the range of about 5mm to about 20mm. In an exemplary embodiment, the height of the helical projection may be about 10mm.

[031] In an exemplary embodiment, the at least one helical projection may be provided in a region on the exterior of the body between about the height of the gas port and the top of the body. In an exemplary embodiment, the at least one helical projection may be provided in a region on the exterior of the body between about the height of the gas port and a height below the top of the body.

[032] In an exemplary embodiment, the handedness of the at least one helix may follow the direction of rotation of the body. For example, where the rotating apparatus is configured to rotate clockwise the helical projection may be right-handed.

[033] In an exemplary embodiment, the gas port may be offset from the base of the body. This offset may allow for the build-up of ash residue on the grate without impeding the flow of syngas.

[034] In an exemplary embodiment, the gas port may include at least one horizontal slot. In an exemplary embodiment, the gas port may include a plurality of horizontal slots spaced apart vertically.

[035] In an exemplary embodiment, the at least one horizontal slot may be narrower at the exterior of the body than the interior of the body.

[036] In an exemplary embodiment, the body includes a plurality of gas ports, spaced apart around the body. By providing discrete gas ports about the body of the rotation apparatus, it is envisaged that rotation of the body may break the fluid connection between a gas port and the rat hole.

[037] In an exemplary embodiment, the body may include at least one scraper on a side of the body at its base. The scraper may push residue along the grate to the at least one residue port.

[038] In an exemplary embodiment, the rotation apparatus may include a central shaft defining the vertical axis, configured to be connected to a rotary drive.

[039] In an exemplary embodiment, the grate may include a plurality of residue ports below the at least one gas port.

[040] In an exemplary embodiment, the at least one residue port includes a downwardly angled exit ramp.

[041] The various components of the gasifier may be manufactured of any suitable material known in the art. By way of example, the vessel may be made of a structural carbon steel plate (for example G 250), while internal components may be made of a stainless steel (for example 304 S/S or a duplex stainless steel). However, it should be appreciated that these examples are not intended to be limiting to all embodiments of the present technology.

[042] According to one aspect of the present disclosure there is provided a gasification plant, including at least one gasifier substantially as herein described.

[043] In an exemplary embodiment, a feedstock conveying system may be provided for the supply of feedstock to the gasifier. In an exemplary embodiment, the conveying system may include a walking floor or reciprocating conveyor onto which the feedstock may be unloaded (for example by a front end loader) and shifted to another conveyor, for example a linear conveyor.

[044] In exemplary embodiments in which the gasification plant includes more than one gasifier, the conveying system may include a cross conveyor for distributing feedstock between the gasifiers.

[045] In an exemplary embodiment, the gasification plant may include at least one dryer configured to reduce the moisture content of the feedstock prior to delivery to the gasifier. In an exemplary embodiment, the dryer may be configured to reduce the moisture content to less than 40%. In an exemplary embodiment, the dryer may be configured to reduce the moisture content to between about 30% to about 40%. In an exemplary embodiment, the dryer may be configured to reduce the moisture content to about 30%. In exemplary embodiments in which the plant includes a heat generator powered by the syngas produced by the gasifier, for example a boiler, at least a portion of the heat output may be used by the at least one dryer.

[046] In an exemplary embodiment, the plant may include a gas disposal system for emissions from the dryers, for example a cyclone for removal of particulates before emission of the gas through a flue.

[047] In an exemplary embodiment, the gas outlet of the gasifier may be connected to at least one particulate separation device. In an exemplary embodiment, the particulate separation device may be a cyclone. [048] In an exemplary embodiment, the gasification plant may include at least one heat exchanger for adjustment of the temperature of the syngas output from the gasifier to suit its intended subsequent use. In an exemplary embodiment, at least one condensate tank may be provided for collection of condensate from the at least one heat exchanger.

[049] In an exemplary embodiment, the gasification plant may include a gas combustion device, for example a gas flare (also known as a flare stack), for burn-off of the syngas.

[050] In an exemplary embodiment, the gasification plant may include at least one electrical power generation device fuelled by the gas output from the gasifier. In an exemplary embodiment, the electrical power generation device may include a generator driven by a turbine powered by a heat generation device (such as a boiler) which is fuelled by the gas output. In an exemplary embodiment, the electrical power generation device may include a generator powered directly by combustion of the gas output.

[051] For a firmware and/or software (also known as a computer program) implementation, the techniques of the present disclosure may be implemented as instructions (for example, procedures, functions, and so on) that perform the functions described. It should be appreciated that the present disclosure is not described with reference to any particular programming languages, and that a variety of programming languages could be used to implement the present invention. The firmware and/or software codes may be stored in a memory, or embodied in any other processor readable medium, and executed by a processor or processors. The memory may be implemented within the processor or external to the processor.

[052] In particular, it is envisaged that in exemplary embodiments control of the gasifier and gasification plant may be performed by at least one processor.

[053] A general purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a digital signal processor (DSP) and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. The processors may function in conjunction with servers and network connections as known in the art.

[054] The steps of a method, process, or algorithm described in connection with the present disclosure may be embodied directly in hardware, in a software module executed by one or more processors, or in a combination of the two. The various steps or acts in a method or process may be performed in the order shown, or may be performed in another order. Additionally, one or more process or method steps may be omitted or one or more process or method steps may be added to the methods and processes. An additional step, block, or action may be added in the beginning, end, or intervening existing elements of the methods and processes.

[055] The above and other features will become apparent from the following description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[056] The detailed description of the drawings refers to the accompanying figures in which:

FIG. 1A is a first perspective view of an exemplary gasification plant;

FIG. IB is a second perspective view of the exemplary gasification plant;

FIG. 2A is a perspective view of an exemplary gasifier;

FIG. 2B is a perspective cross-sectional view of the exemplary gasifier;

FIG. 2C is a cross-sectional view of the exemplary gasifier;

FIG. 2D is a perspective view of an exemplary manifold for use with the exemplary gasifier;

FIG. 2E is an inset cross-sectional view of a portion of the exemplary gasifier;

FIG. 2F is a perspective view of an exemplary grate for use with the exemplary gasifier;

FIG. 3A is a perspective view of an exemplary rotation apparatus for use with the exemplary gasifier;

FIG. 3B is a cross-sectional view of the exemplary rotation apparatus;

FIG. 3C is a cross-sectional view of a portion of an exemplary gas port of the exemplary rotation apparatus, and

FIG. 4 is a further cross-sectional view of the exemplary gasifier.

DETAILED DESCRIPTION OF THE DRAWINGS

[057] FIG. 1A and FIG. IB shows an exemplary gasification plant 100 in accordance with one aspect of the present technology. The exemplary gasification plant 100 illustrated includes a first gasifier 200-1 and second gasifier 200-2 positioned next to each other, although it should be appreciated that this is not intended to be limiting to all embodiments (for example a gasification plant may include one gasifier, or more than two gasifiers.

[058] The exemplary gasification plant 100 includes a feedstock conveying system for the supply of feedstock to the gasifiers 200-1 and 200-2. Examples of suitable feedstock may include, but not be limited to, waste materials such as municipal wastes; wastes produced by industrial activity; biomedical wastes; carbonaceous material inappropriate for recycling (such as non-recyclable plastics or tyres); biomass; agricultural wastes; municipal solid waste; hazardous waste and industrial waste. Examples of biomass may include, but not be limited to, remains from fruit, vegetable and grain processing; wood (including saw mill residues); other plant matter; and manure. In the exemplary embodiments such as that illustrated the conveying system may include a walking floor 102 onto which the feedstock may be unloaded and shifted to a linear belt conveyor 104, before conveying of the feedstock up a first inclined conveyor 106 to rotary dryers 108-1 and 108-2. The rotary dryers 108-1 and 108-2 may be controlled to reduce the moisture content of the feedstock, for example to less than 40%, preferably about 30% or less.

[059] The dried feedstock from the dryers 108-1 and 108-2 is conveyed by a second inclined conveyor 110 to a feed bin 112. A third inclined conveyor 114 conveys the feedstock from the feed bin 112 to a cross conveyor 116 on demand, for distribution of the feedstock to the first and second gasifiers 200-1 and 200-2.

[060] Operation of the gasifiers 200-1 and 200-2 will be described in greater detail below, but ultimately output syngas which is processed by first and second cyclones 118-1 and 118-2 to separate particulate matter from the syngas, and passed through first and second heat exchangers 120-1 and 120-2 to adjust its temperature to that suited to its intended use. In the exemplary embodiment illustrated a condensate tank 122 is for collection of condensate from the heat exchangers 120-1 and 120-2.

[061] In an exemplary embodiment, a portion of the processed syngas may be fed back to the first and second gasifiers 200-1 and 200-2 to assist with the gasification process.

[062] Otherwise, the syngas may be subsequently processed in accordance with the needs of the gasification plant 100. For example, the exemplary gasification plant 100 may include a gas combustion device, such as a burner 124 into flare stack 126 for burn-off of the syngas.

[063] The exemplary gasification plant 100 may include one or more heat generators powered by the syngas produced by the gasifiers 200-1 and 200-2, for example a first boiler 128-1 and a second boiler 128-2. In an exemplary embodiment, the first boiler 128-1 and/or second boiler 128-2 may be used to drive an electrical power generator (not illustrated in FIG. 1A or FIG. IB). In an alternate exemplary embodiment, the syngas may power a generator driven by a combustion engine.

[064] In exemplary embodiments in which the gasification plant 100 includes a heat generator, at least a portion of the heat output may be used by the dryers 108-1 and 108-2 - for example connection of a heat output 130 of the first boiler 128-1 (connection not illustrated). In the exemplary embodiment illustrated a gas disposal system for emissions from the dryers 108-1 and 108-2 is provided, including a cyclone 132 for removal of particulates before emission of the gas through a flue 134 (connections indicated by the dashed line in FIG. IB).

[065] Referring to FIG. IB, the exemplary gasification plant 100 includes first and second residue extraction augers 136-1 and 136-2 for transport of feedstock residue from the first and second gasifiers 2001- and 200-2 respectively to residue outlets 138-1 and 138-2. A residue containing means may be provided, for example a pit or tray, from which the residue may be collected.

[066] Reference to "residue" should be generally understood to mean the residual material produced during the processing of the feedstock by the gasifiers 200-1 and 200-2. These may include the solid and semi-solid by-products of the process such as char, ash, and/or any incompletely converted feedstock passed from the gasification chamber. The residue may also include materials recovered from downstream gas conditioning processes, for example, from the cyclones 118-1, 118- 2, or 132.

[067] FIGs. 2A, 2B and 2C show an exemplary gasifier 200 according to one aspect of the present technology, which may be used in the exemplary gasification plant 100. The gasifier 200 includes a vessel having a cylindrical upper portion 202, a conical lower portion 204, and an outer cylindrical portion 206 connected to the conical lower portion 204 and overlapping the exterior of the cylindrical upper portion 202 with a space therebetween.

[068] Referring to FIG. 2B and FIG. 2C, the cylindrical upper portion 202 of the vessel includes a centrally positioned feedstock inlet 208 through which feedstock is introduced to an upper portion 210 of a gasification chamber within the vessel. The gasifier 200 includes a feedstock inlet closing device, which in this exemplary embodiment is provided by a conical plug 212 movable by a linear actuator 214 between a position seated against the feedstock inlet 208 to close the gasification chamber from atmosphere, and a position away from the feedstock inlet 208 to allow the introduction of feedstock as required. It is envisaged that the conical shape of the plug 212 may assist with distribution of feedstock about the chamber, with the feedstock falling onto the tip of the plug 212 and directed outwardly.

[069] The exemplary gasifier 200 includes an upper oxidant manifold 216-1, and an upper syngas manifold 218-1 below the upper oxidant manifold 216-1, connecting gas inlets into the gasification chamber to respective sources of oxidant and syngas. The exemplary gasifier 200 also includes a lower oxidant manifold 216-2, and a lower syngas manifold 218-2 below the lower oxidant manifold 216-2, connecting gas inlets into the gasification chamber to respective sources of oxidant and syngas. The lower manifolds 216-2 and 218-2 connect to the gasification chamber below the upper manifolds 216-1 and 218-1.

[070] In an exemplary embodiment, the upper manifolds 216-1 and 218-1 may connect to the gasification chamber at a height at which the pyrolysis zone is expected to be, while the lower manifolds 216-2 and 218-2 may connect to the gasification chamber at a height at which the combustion zone is expected to be. The supply of oxidant and/or syngas to the upper and lower manifolds may be controlled separately in accordance with the requirements of the process occurring at each zone. [071] FIG. 2D illustrates an exemplary configuration for one or more of the manifolds, designated manifold 216. The exemplary manifold 216 includes a manifold conduit 220 for surrounding the gasifier 200, with a plurality of branch conduits (six in the embodiment illustrated) disposed around the manifold conduit 220 and extending inwardly. Each of the branch conduits includes a thermal expansion joint in the form of bellows 222-1 to 222-6 terminating in a branch end 224-1 to 224-6. The bellows 222-1 to 222-6 allow for thermal expansion of the vessel resulting from the gasification process.

[072] Returning to FIG. 2B and FIG. 2C, the gasifier 200 includes a rotation apparatus (herein referred to as "spinner") 300 positioned between the upper portion 210 of the gasification chamber and a lower portion 226 of the gasification chamber within the conical lower portion 204 and outer cylindrical portion 206. Further detail of an exemplary embodiment of the spinner 300 will be discussed below with reference to FIGs. 3A to 3C.

[073] A residue grate 228 is provided below the spinner 300 and between the upper portion 210 of the gasification chamber and a lower portion 226 of the gasification chamber. Referring to inset 230, with zoomed in view shown in FIG. 2E, the residue grate 228 is secured to a flange 232 of the cylindrical upper portion 202. Referring to FIG. 2F, the residue grate 228 includes an annular plate 234 having a plurality of residue ports having residue apertures 236-1 to 236-4 exiting via downwardly angled exit ramps 238-1 to 238-4 (noting that exit ramp 238-4 is not shown in FIG. 2F). A collar 240 rises from the inner edge of the annular plate 234.

[074] Returning to FIG. 2E, residue produced by the gasification process falls to the residue grate 228 and passes through into the lower portion 226 of the gasification chamber as indicated by dashed arrow 242. Syngas flows through the interior of the spinner 300, conical lower portion 204, and up into the cavity between the conical lower portion 204 and outer cylindrical portion 206 as indicated by arrow 244, where a gas outlet 246 is positioned and regulated by controllable valve 248 (not shown in FIG. 2E, but see FIGs. 2B and 2C).

[075] Referring to FIG. 2B and 2C, a rotary drive 250 rotates drive shaft 252, which is coupled to the spinner 300. A residue outlet 254 includes a side exit 256, with a bladed residue extractor 258 coupled to the drive shaft 252 and configured to push residue through the side exit 256. A vibrating motor 260 may be provided to encourage the residue to settle in the base of the conical lower portion 204.

[076] FIGs. 3A and 3B show an exemplary embodiment of a rotation apparatus, for example spinner 300. The spinner 300 includes a hollow conical body 302 made of a side wall having an exterior surface 304 and an interior surface 306. In use the conical body 302 is orientated such that the tip 308 is above the base 310. [077] A central spinner shaft 312, configured to be coupled to the drive shaft 252, defines a vertical axis of rotation for the spinner 300. The spinner shaft 312 is connected to the body 302 by an upper brace 314 and a lower brace 316. Referring to FIG. 2B, the lower brace includes a plurality of apertures through which gas may pass into the lower portion 226 of the gasification chamber.

[078] The body 302 includes a plurality of gas ports 318-1 to 318-3 between the exterior surface 304 and interior surface 306 of the conical body 302, spaced apart from each other around the conical body 302. Referring to FIG. 3C, each of the gas ports 318-1 to 318-3 (a portion of which is indicated by arrow 318 in FIG. 3C) includes a plurality of alternating bars 320-1 to 320-n and slots 322-1 to 322-n extending horizontally. In the exemplary embodiment illustrated, each of the slots 322-1 to 322-n widens between a slot mouth 324 on the exterior 304, and a slot exit 326 at the interior 306, preferably each slot 322-1 to 322-n has a conical shape. As shown the bars 320-1 to 320-n may have a V or triangular shape.

[079] Referring to FIG. 4, the spacing apart of gas ports 318-1 to 318-3 (noting that only gas port 318-2 may be seen in FIG. 4) and rotation of the spinner 300 may assist with breaking down the formation of cavities within the feedstock - particularly rat holes tracking from the gas inlets (for example from upper syngas manifold 218-1). For example, where a rat hole (indicated by arrow 400) is formed leading to the gas port 318-2, rotation of the spinner 300 will break the pathway to the gas port 318-2.

[080] Returning to FIGs. 3A and 3B, the lower edge of the gas ports 318-1 to 318-3 is offset from the base 310 of the body 302. This offset may allow for the build-up of ash residue on the grate 228 (not shown in FIGs. 3A or 3B, but see FIG. 2B for example) without impeding the flow of syngas into the gas ports 318-1 to 318-3.

[081] In the exemplary embodiment shown, a helical protrusion 328 is provided on the exterior surface 304 of the body 302. In this exemplary embodiment, the helical projection 328 is right handed, with clockwise rotation of the spinner 300 lifting feedstock or residue resting on it. The helical projection 328 is provided in a region on the exterior surface 304 of the body 302 between the upper height of the gas ports 318-1 to 318-3 and a point below the top 308 of the body 302.

[082] In this embodiment, the height of the helical projection 328 is about 10 mm, however it should be appreciated that this is not intended to be limiting to all embodiments.

[083] In the embodiment illustrated the spinner 300 includes a plurality of body 302 mounted blades 330-1 to 330-2at about the upper height of the gas ports 318-1 to 318-3. It should be appreciated that while only body mounted blades 330-1 and 330-2 may be seen in FIG. 3A, the spinner 300 may include zero, one, or more than two body mounted blades. A stirrer shaft 332 extends from the top 308 of the body 308, having a conical cap 334 at an end distal from the body 302. Stirring members in the form of a lower leveler blade 336-1 and an upper leveler blade 336-2 extend in opposing directions from the stirrer shaft 332.

[084] The leveler blades 336-1 and 336-2 in this exemplary embodiment are angled upward at an angle of between about 20 to about 25 degrees relative to level, however it should be appreciated that this is not intended to be limiting to all embodiments. Alternatively, there may be zero, one or more than two leveler blades attached to the stirrer shaft 332.

[085] The spinner 300 includes a plurality of vertically oriented scrapers 338-1 to 338-3 on the exterior surface 304 of the body 302 at its base 310. As the spinner 300 rotates, the scrapers 338-1 to 338-3 push residue along the grate 228 to the residue apertures 236-1 to 236-4 (see FIG. 2F) to fall into the lower portion 226 of the combustion chamber (see FIG. 2C).

[086] Throughout this specification, the word "comprise" or "include", or variations thereof such as "comprises", "includes", "comprising" or "including" will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps, that is to say, in the sense of "including, but not limited to".

[087] Embodiments described herein 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, in any or all combinations of two or more of said parts, elements or features.

[088] Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

[089] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the disclosure and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

[090] Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.

Claims

1. A gasifier, including:

a vessel having a gasification chamber with a feedstock inlet;

a body; and

a grate positioned between the upper and lower portions of the gasification chamber, including at least one residue port below the at least one gas port of the rotation apparatus.

2. The gasifier of claim 1, wherein the vessel includes a substantially cylindrical upper portion and a tapered lower portion.

3. The gasifier of claim 2, wherein the vessel includes an outer cylindrical portion connected to the tapered lower portion and overlapping the cylindrical upper portion.

4. The gasifier of any one of claims 1 to 3, wherein the feedstock inlet is provided near or at the centre of a top of the gasification chamber.

5. The gasifier of any one of claims 1 to 4, wherein the gasifier includes a feedstock inlet closing device.

6. The gasifier of claim 5, wherein the feedstock inlet closing device includes a plug configured to be moved between a position away from the feedstock inlet and a position seated in the feedstock inlet, wherein the plug is tapered, with a wider portion of the plug below a narrower portion of the plug, and the feedstock inlet closing device is configured to lower the plug into the gasification chamber to open the feedstock inlet, and raised to close the feedstock inlet.

7. The gasifier of any one of claims 1 to 6, including at least one gas inlet in the upper portion of the gasification chamber.

8. The gasifier of claim 7, wherein the at least one gas inlet includes at least one first gas inlet for the supply of a first type of gas, and at least one second gas inlet for the supply of a second type of gas.

9. The gasifier of claim 8, wherein the first type of gas is an oxidant.

10. The gasifier of claim 8 or claim 9, wherein the second type of gas is a syngas.

11. The gasifier of any one of claims 8 to 10, wherein the at least one second gas inlet is below the at least one first gas inlet in the upper portion of the gasification chamber.

12. The gasifier of any one of claims 8 to 11, wherein the gas supply provided through the at least one first gas inlet is controlled independently from the gas supply provided through the at least one second gas inlet.

13. The gasifier of any one of claims 7 to 12, wherein the at least one gas inlet includes a plurality of gas inlets disposed around the upper portion of the gasification chamber.

14. The gasifier of claim 13, further including a manifold connected to the plurality of gas inlets disposed around the upper portion of the gasification chamber.

15. The gasifier of claim 14, wherein each of the plurality of gas inlets is connected to the manifold by a branch conduit having a thermal expansion joint.

16. The gasifier of any one of claims 1 to 15, wherein the body of the rotation apparatus tapers from a broad base below the at least one gas port to a top above the at least one gas port.

17. The gasifier of any one of claims 1 to 16, wherein the body of the rotating apparatus includes at least one outwardly projecting stirring member.

18. The gasifier of claim 17, wherein the at least one stirring member is positioned between a top of the body and the at least one gas port.

19. The gasifier of any one of claims 1 to 18, including a stirrer shaft located within the upper portion of the gasification chamber and having at least one stirring shaft member projecting outwardly from the stirrer shaft.

20. The gasifier of claim 19, wherein the stirrer shaft is connected to, and projects upwardly from, the body.

21. The gasifier of claim 19 or claim 20, wherein the at least one stirring shaft member is a blade, and the blade is oriented such that an edge of the blade faces in the direction of rotation of the stirrer shaft.

22. The gasifier of any one of claims 19 to 21, wherein the at least one stirring member is angled upward from the stirrer shaft relative to level.

23. The gasifier of any one of claims 1 to 22, wherein the body includes at least one helical projection on an exterior of the body.

24. The gasifier of claim 23, wherein a height of the helical projection from the exterior of the body is within a range of about 5mm to about 60mm.

25. The gasifier of any one of claims 23 to 25, wherein a handedness of the at least one helix follows the direction of rotation of the body.

26. The gasifier of any one of claims 1 to 25, wherein the gas port includes a plurality of horizontal slots spaced apart vertically.

27. The gasifier of claim 26, wherein each of the horizontal slots is narrower at the exterior of the body than an interior of the body.

28. The gasifier of any one of claims 1 to 27, wherein the body includes a plurality of gas ports, spaced apart around the body.

29. The gasifier of any one of claims 1 to 28, wherein the body includes at least one scraper on a side of the body.

30. The gasifier of any one of claims 1 to 29, wherein the at least one residue port includes a downwardly angled exit ramp.

31. The gasifier of any one of claims 1 to 30, wherein the grate includes a plurality of residue ports below the at least one gas port.

32. A gasification plant, including:

at least one gasifier as claimed in any one of claims of 1 to 31.

33. The gasification plant of claim 32, including one or more of the following components:

(i) a feedstock conveying system for supply of feedstock to the gasifier;

(ii) at least one dryer configured to reduce the moisture content of the feedstock prior to delivery to the gasifier;

(iii) a heat generator powered by gas produced by the gasifier; and

(iv) at least one electrical power generation device fueled by gas output from the gasifier.

34. The gasification plant of claim 33, wherein the at least one dryer is configured to reduce the moisture content to less than 40%.

35. The gasification plant of claim 33 or claim 34, wherein at least a portion of heat output from the heat generator is used by the at least one dryer.