WO2009099341A2

WO2009099341A2 - Method and apparatus for the production of carbon fro carboniferous feedstock

Info

Publication number: WO2009099341A2
Application number: PCT/NZ2009/000010
Authority: WO
Inventors: Wolfgang Weinzettl
Original assignee: Eco Technology Limited
Priority date: 2008-01-30
Filing date: 2009-01-30
Publication date: 2009-08-13
Also published as: WO2009099341A3; AU2009210885A1

Abstract

The present invention is directed apparatus for producing a carbon product from carboniferous material, such materials including wood and other green waste, various biomass, and waste materials such as tyres and plastics. A reaction chamber of specific characteristics heats the carboniferous feedstock to a threshold temperature to initiate a process of carbonisation to yield a carbon product. The apparatus is adaptable to continuous and semi-continuous processing of feedstock.

Description

METHOD AND APPARATUS FOR THE PRODUCTION OF CARBON FROM CARBONIFEROUS FEEDSTOCK

FIELD OF INVENTION

The present invention is directed to method and apparatus for the batch and/or continuous production of a predominantly carbon product from a carboniferous feedstock which may comprise biomass.

BACKGROUND DESCRIPTION

Worldwide, charcoal is of significant importance in a number of roles. In many nations charcoal constitutes one of the more important fuels, and large areas of forest are sometimes felled for its wood content to produce carbon. Charcoal, essentially carbon, also finds its way into various industrial uses: for instance it is often used in metal purification or production. Activated charcoal is used medically and well as in purification processes, and graphite (a conductive allotrope of carbon) is important for its electrical as well as mechanical properties. These represent some of the more common current uses of carbon, but likely only a small proportion of actual and foreseeable uses. Accordingly, carbon is a reasonably important commodity.

While carbon exists in large quantities in coal deposits, most carbonaceous deposits tend to be high in impurities such as sulphur, etc. They tend to represent quite a different type of product than carbon produced from biomass such as timber - the more common feedstock for charcoal production. Economics tends to favour the production of charcoal from woody materials such as timber, though this is neither an endless nor renewable source unless sustainable forestry techniques are used. Unfortunately much of the world's charcoal probably comes from non-sustainable forestry techniques - even apart from that, trees tend to grow slowly compared to other plants.

Accordingly, while wood represents an excellent raw material for charcoal production, wood and timber typically represent a small proportion of the total biomass that could be made available for charcoal production if an efficient process existed. Being able to efficiently produce charcoal from either or both of woody and non-woody plant material would be a significant achievement. Being able to extend this to carbon containing material which comprised waste (e.g. used tyres) would also be an advantage - a reasonable part of the world's refuse comprises material which could lend itself to a charcoal producing process, hence providing an opportunity to kill two birds with one stone by disposing of waste through the production of a valuable commodity — charcoal.

Michael J. Antal of the University of Hawaii has realised, for the last decade, the importance of efficient charcoal production from a wide range of biomass feedstocks. Two patent families (WO9629378 (see for instance AU718177B) and WO03002690 (see for instance US 6790317) ) summarise his work, as well as summarising the limitations of the prior art which he sought to improve upon. To prevent duplication, the applicant shall refer to the prior art descriptions of Antal' s patents as representing a reasonable summary, of the prior art, though does not necessarily agree with any conclusions or prior art analyses, drawn in these patent specifications. Reference to AntaPs work is also made in the article Ind. Eng. Chem. Res. 2006, 45, 585-599 describing updated studies on flash carbonisation.

Antal's patents propose method and apparatus for the batch processing of biomass to charcoal. From an industrial production viewpoint, batch processing is typically less favourable than continuous processing or semi-continuous processing. Equipment tends to be tied up for longer, and additional steps are usually required for the handling of materials in batch processes. Consequently, batch processes are typically less economical than continuous or semi-continuous processing. Accordingly it would be a potentially realisable advantage and of potential value to create a continuous or semi- continuous process for the conversion of carboniferous waste and/or biomass type material into charcoal.

Further, analysis of the subject matter (of Antal's patents) by the present inventor suggests that it may be problematic to convert these processes into an industrial scale process. It is commonly known that scaling bench-top laboratory trials to an industrial scale process is often fraught with difficulties and unpredictable. Accordingly it is considered to be of potential commercial benefit to provide a viable industrial scale process and/or apparatus for the production of charcoal from biomass type material, and which would be of potentially greater value if it was also amenable or adaptable for other carboniferous feedstocks (particularly waste). Used tyres are one possible waste product. Used tyre disposal has long been a problem as tyres are generally not economic to recycle and their disposal (generally landfill) worldwide is becoming an ever-increasing problem. A process which could deal with (long-standing) problematic carboniferous waste products such as tyres can help address an increasing need for a solution to certain waste disposal issues.

Accordingly there is a need to provide an improved process and/or apparatus capable of industrial scale conversion of carbon containing material into a carbon product.

Accordingly, it is an object of the present invention to address the above problems.

It is a further object of the present invention to provide an improved process for the conversion of suitable carbon containing feedstock into a carbon product.

At the very least it is an object of the present invention to provide the public with a useful alternative choice.

Aspects of the present invention will be described by way of example only and with reference to the ensuing description.

GENERAL DESCRIPTION OF THE INVENTION

For clarity, it is beneficial to define several of the terms used within this specification:

The term 'biomass' refers to material originating from plants or animals. Ideally, for use with the present application, this material is predominantly solid, rather than being a liquid. It is anticipated though that a feedstock of solid material may be contaminated with a liquid component. Examples of biomass include, but are not restricted to: plant clippings, wood, plant foliage, timber processing waste (of plant material), fruit, plant root material, animal carcasses and parts thereof, animal offal and solid waste from meat processing plants, etc.

The term 'carboniferous feedstock' refers to a feedstock made up predominantly of carboniferous, or carbon containing, material. While biomass is likely to represent a common feedstock, there are a range of other materials which can be considered for use with various embodiments of the present invention. These include, but are not restricted to: woody materials from building products and demolition materials, thermosetting plastics materials (thermoplastic plastics can be problematic in larger . quantities as bulk liquification prior to carbonisation can affect the efficiency of the process), whole and shredded vehicle tyres, materials composed mainly of carbon based organic materials and compounds, etc.

The term 'charcoal product' refers to the product from the process according to an embodiment of the present invention and which, other than impurities and foreign materials, comprises predominantly carbon in an elemental form.

According to one aspect of the present invention there is provided carbon producing apparatus for the production of a carbon product from a carboniferous feedstock, said carbon producing apparatus comprising a process chamber in turn comprising: - a reaction chamber capable of containing said carboniferous feedstock during its conversion to a charcoal product, chamber heating means capable of increasing the internal temperature of the process chamber to in excess of 350°C, control means for controlling chamber heating means so as to increase and maintain the internal temperature of the process chamber to in excess of 350⁰C for the conversion of carboniferous feedstock to a carbon product.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the relationship between the reaction chamber and chamber heating means being such that, the chamber heating means provides one or more effective heated surface areas acting within the reaction chamber in which 'd^' represents the longest dimension of either a said effective heated surface area, or the length spanning and including effective heated areas associated with a face of said reaction chamber; the relationship between the reaction chamber being further defined such that the reaction separation distance, comprising the average distance of any loaded carboniferous feedstock in said reaction chamber to an effective heated surface area (as defined in the specification) within the reaction chamber, is less than 1.5 times 'dt,_s'. According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the reaction separation distance is less than or equal to 1.0 times 'dhs -

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which said reaction chamber has a length 'I_n,' and is of substantially constant cross-section along its length 'I_n,'.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which there is an effective heated surface area on a face of the reaction chamber which is substantially perpendicular to length 'I_n,'.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which there is an effective heated surface area on a face of the reaction chamber which is substantially parallel to length 'I_n,'.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which there are provided an- effective heated surface area or areas whose total area comprises at least 80% of average cross-sectional area of the reaction chamber.

According to another aspect of the present invention there, is provided carbon producing apparatus, substantially as described above, in which the cross-sectional diameter of the reaction chamber is substantially constant along dimension 'I_n,' , and the total area of heated surface area(s) associated with the reaction chamber comprises at least a proportion of the internal surface area of the reaction chamber calculated by

(2 / 'dg/ + 2) * 100 (as a percentage), and wherein 'd_m' represents the average cross- sectional diameter or span of the reaction chamber along dimension 'I_n,', said proportion being 18% or greater.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which at least the internal surface of the reaction chamber is substantially non-porous. . According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which at least the internal surface of the reaction chamber is made of a ceramics material.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which a heating element may comprise one or more members of the group comprising: electrically powered heating elements, conduits conveying heated material, and conductive elements conveying heat from a heat source.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in^" which the reaction chamber has at least two access apertures, one for the introduction of material into the reaction chamber, and one for the removal of material from the reaction chamber.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the two access apertures are on opposing sides of the reaction chamber.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the access aperture for the introduction of material into the reaction chamber is connected to an a feed system for introducing material into said reaction chamber, said feed system comprising one or more of: an automated feed system, a continuous feed system, and a semi-continuous feed system feeding discrete lots of feedstock in a repetitive manner.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which at least one of the following parameters of the feed system can be altered: feed rate, feed timing, period of operation.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the feed system introduces feedstock into an introduction portion, and which action further pushes existing feedstock within the introduction portion into the reaction chamber. According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which feedstock within the introduction portion is preheated by one or more of the following methods: radiant heat from the reaction chamber, heat conducted from the reaction chamber, waste heat recovered from the carbonisation process, electrical heating elements, heat produced from the combustion of combustible gases recovered from the carbonisation process, and heat from gases and vapours recovered from the carbonisation process.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the access aperture for the removal of material from the reaction chamber is connected to a carbon product removal system.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the action of the feed system pushing feedstock into the introduction portion, and subsequently forcing existing material within the introduction portion into the reaction chamber, also forces material within the reaction chamber into a cooling section.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which operation of said feed system is controlled by the control means such that feedstock is forced from the reaction chamber to the cooling section prior to full conversion to a charcoal product, and in which further carbonisation occurs within the cooling section as a consequence of the residual heat of the partly carbonised feedstock removed from the reaction chamber.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which material forced from the reaction chamber into the cooling section acts on existing material in the cooling section and forces it into product collection means.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which said apparatus substantially excludes air from coming into contact with feedstock and/or product within or removed from the reaction chamber.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which there is a heat exchanger associated with said cooling section, and which recovers waste heat from the cooling section.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which feedstock is introduced ultimately into the reaction chamber by an arrangement comprising at least one of the following mechanisms: a piston arrangement, a rotating screw arrangement, and a rotating chamber arrangement.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which the control means monitors the temperature within the reaction chamber, and initiates the introduction of fresh feedstock into the reaction chamber by feedstock drive means when specific criteria are met, said criteria comprising one or more of: a predetermined duration, a predetermined duration from when other criteria (herein) are met, when the amount of energy supplied to the chamber heating means to maintain a particular temperature crosses a predetermined threshold or point, measuring the flow of gases and vapours from the chamber and determining when the flow rate crosses a certain predetermined point, and monitoring via sensors for a particular vapour or gaseous by-product indicating when a certain point in the carbonisation reaction has been reached. ^'

According to another _ aspect of the present invention there is provided carbon producing apparatus, substantially as described above, which includes plumbing for the removal of exhaust gases and collecting this in one or more fractions.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which a fraction of the exhaust gases are reintroduced directly or indirectly into the reaction chamber. According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which a compressor is used to reintroduce gaseous materials into the reaction chamber.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, in which includes plumbing for removing exhausted gases from the carbonisation process, and which gases are used to drive a turbine which is connected or connectable to an electrical generator.

According to another aspect of the present invention there is provided carbon producing apparatus, substantially as described above, which comprises an elongate process chamber of substantially constant cross-section, and which chamber includes an introduction portion followed by a portion comprising the reaction chamber and followed by a cooling section; there being feed means capable of forcing an introduced supply of feedstock into the introduction portion intermittently, and which action forces material within the process chamber progressively therethrough; and wherein the chamber heating means of the reaction chamber is capable of raising the temperature of material within the reaction chamber to a temperature within the inclusive range of 400° to 550⁰C; and in which the longitudinal length of the reaction chamber portion of the process chamber is equal to or greater than the average cross-sectional diameter or span across the reaction chamber.

According to a further aspect of the present invention there is provided a carbon product produced from carbon producing apparatus substantially as described above.

According to yet a further aspect of the present invention there is provided a method for producing a carbon product comprising the use of carbon producing apparatus substantially as described above, said method comprising introducing carboniferous feedstock into the reaction chamber, and raising the temperature in excess of 35O⁰C for a period of time.

According to another aspect of the present invention there is provided a method for producing a carbon product, substantially as described above, in which the amount of energy introduced to carboniferous feedstock within the reaction chamber, measured per litre of carboniferous material, is at least 500 kJ over a period within a reaction initiation period in the range of 3 to 20 minutes inclusive.

According to another aspect of the present invention there is provided a method for producing a carbon product, substantially as described above, in which the carboniferous feedstock comprises tyres.

According to another aspect of the present invention there is provided a method for producing a carbon product, substantially as described above, which includes removing and recovering hydrocarbon and/or condensible gaseous by-products from the carbonisation process.

' According to another aspect of the present invention there is provided a method for producing a carbon product, substantially as described above, in which carbonised product is screened to remove non-carbon impurities in the product obtained from the reaction chamber.

" According to a still further aspect of the present invention there is provided a carbon product obtained from a method substantially as described above.

The present invention attempts to improve upon the prior art in terms of providing a means of processing carboniferous feedstock to a carbon product by a reaction which, once initiated, is substantially self sustaining. For an ideal carboniferous feedstock the charcoal producing process is exothermic, and once initiated will be self-sustaining in ideal conditions. It is creating these ideal conditions which can be challenging.

Initial research has indicated that the reaction chambers and methods of Antal in his patents do not present ideal conditions, and for many types of biomass the reactions to produce a carbon product may be difficult in terms of initiation and sustaining the reaction. Further, the Antal apparatus is very much a batch process and is not readily adaptable to a continuous process.

The research and experimentation of the applicant has indicated that the process chamber size and shape is of some importance in creating ideal conditions for a self- sustaining carbon producing reaction from carboniferous feedstock. Certain chamber configurations may fail to achieve one or more of: initiate a carbonisation process effectively, be difficult to sustain or require a considerable amount of energy to maintain the process, or fail to carbonise fully throughout the carboniferous mass being carbonised. All of these factors are detrimental to an effective and reliable carbonisation process suitable for potential commercial use.

In simple terms, an embodiment of a reaction chamber according to the present invention, in which heating elements are present in its base, will be squat rather than tall, i.e. having a low aspect ratio — for simplicity, in this example we assume the reaction chamber is oriented such that the heating element is in the base (or bottom face) though various embodiments may be oriented differently.

For practical embodiments, heat applied to the process chamber is typically applied (for economic and reliability/maintenance reasons) at one face of the chamber, the heat spreading outwardly to heat the contents of the chamber. However it is envisaged also that heat may be applied to more than one face of the reaction chamber — again a matter of user choice.

In many embodiments heat is applied to the base of the chamber, as gravity tends to pack the contents towards the base, though again it is mentioned that some embodiments may be vertically oriented or inclined to utilise gravity to help feed reactant into the reaction chamber, or for other reasons. Regardless, any reaction is likely to start in this heated region first, and travel away therefrom (i.e. upwardly if the heating portion is in the base). If we compare the preferred low 'aspect (squat) arrangement with a tall chamber (again we use the example of a reaction chamber with the heat applied at its basal face) it is noted that a tall chamber has two primary difficulties: i) the carboniferous material can act as an insulator preventing heat from the basal elements spreading to adequately heat the chamber in the regions farthest from the heating portion(s), and ii) if reaction commences at. the base, it may have difficulty propagating upwardly (or away from the region the reaction started) for any significant distance, depending on the actual feedstock. Consequently, the low aspect ratio 'squat' design for a process chamber has the potential capability of addressing some of these issues and goes some way towards creating more ideal conditions within the chamber.

AntaPs work deals with high aspect ratio reaction chambers — i.e. they tend to be tall and cylindrical. Hence the farthest contents of the reaction chamber tend to be some distance away from the heating element/region. Such chambers are further exemplified in the recent article in Ind. Eng. Chem. Res. 2006, 45, 585-599, which again propose high aspect ratio chambers with a base heating element. The present applicant's work suggests that the efficiency of the carbonisation process may be adversely affected if there is a large temperature differential across the contents (carboniferous feedstock) when the carbonisation reaction begins; this potentially being more so for some types of feedstock. Consequently this may explain the relative efficiency of test carbonisation reactions the applicant has performed as bench-top trials, and which consequently teaches away from the use of high aspect ratio process chambers as favoured by the prior art.

In relation to the term 'aspect ratio', it should be appreciated that the reference point for determining aspect ratio is the primary heated surface. Hence, for designs such as Antal's reaction chamber, comprising a cylinder with a heated^' base, the aspect ratio comprises height/width (or diameter in the case of a cylinder). If instead (using a rectangular cuboid of the same general proportions as Antal's reaction chamber, for simplicity) a side wall is heated rather than the base, then the aspect ratio would be width/height. Effectively we are determining the maximum distance of feedstock in a loaded reaction chamber from the heating face (applying heat to the reaction chamber) and comparing this to the size of the heated portion of the heating face - hence a larger heating face potentially supports feedstock which is farther from the face. There will be practical upper limits in which efficiency and productivity drops, though this will depend on a number of factors peculiar to each case, including the type of feedstock, moisture content of the feedstock, etc. Optimisation trials and data are therefore recommended in the commissioning of any particular embodiment of the present invention (e.g. apparatus optimised for processing dry used tyres will typically be different to that for processing wet biomass). It is also anticipated that a reaction chamber may also have more than one heated face. In such a case the reaction chamber may not appear as 'squat' as one with a single heating face, but still work as effectively. Again, the guiding principle is the maximum distance of feedstock in a fully loaded reaction chamber from a heating face or source. For simplicity, most of the following description will (unless otherwise noted) refer to a rectangular cuboid shaped reaction chamber with one heated face (which can be assumed to be the base, unless otherwise noted, for simplicity).

As it is envisaged also that the process chamber may take a number of different configurations other than the 'squat' embodiment described above, and still possess the same potentially advantageous features, it is perhaps best to describe the various relationships mathematically. We shall refer to a reaction chamber, which is the part of the process apparatus containing the carboniferous feedstock for reaction. The reaction chamber may be the inside of the process chamber, though may comprise a separate component within the process chamber.

Looking at the reaction chamber, identify the main surface containing heating means (there may be more than one surface providing heating in some embodiments). If this surface is heated evenly then take its longest dimension and call this '<4Λ However, the surface may comprise a plurality of heated regions, rather than being substantially evenly heated all over. In this case, take the greatest dimension connecting opposing edges of the heated regions — for instance if there were two circular heated regions, then connect the outermost opposing circumferential points on the two regions (in other words the diameter of each circle plus the distance of separation between the points of closest approach) - and call this 'd_hS'- Where other shaped heating regions are provided, or more than two heating regions present on the surface, find the greatest length possible where the ends of that length lie within or on the edges of heating regions (on that surface) and call this '<4/. Now we have identified 'di,_s'.

Now identify the average distance ^edf_S' of loaded carboniferous material (assuming it substantially fills the reaction chamber and with minimum headroom) from the surface used for calculating ^cdi_ιs\ For a cylindrical vessel standing upright (central axis being vertical) where the bottom end surface is the main heated surface for the purpose of these calculations, then if the top of the loaded carboniferous feedstock above this surface is 'd_hf, then the average distance ^ιd_β is half of '<4/. For alternately shaped vessels, or with other main heated surfaces (e.g. a region of the round wall of the cylinder) the same general principles apply. By way of example, for a cylinder whose entire curved surface is heated, the entire surface will be treated as the main surface and 'df_s will be less than half the radius, In the situation where only part of the curved surface is heated (i.e. the entire length of the cylinder but only part of the circumference) then the heated region alone (or the region delineated by connecting multiple heating points on this surface) is regarded as the main heating surface for the purpose of this analysis.

Having calculated 'c4/ and 'df_S', we can specify that for a reaction chamber the ideal is for ^ιd_β to be less than or equal to 1.5 times 'di_ts'. More preferably 'd_β is less than or equal to 1.25 times ^ed_hs' and more preferably in the range 'd_f,_s':'d_β' of 0.3 to 0.8 inclusive. By maintaining the vessel dimensions within these ranges, the user has the flexibility of utilising a different number of chamber shapes and knowing how best to initiate and sustain reaction. Hence, a tall upright cylinder could be used, but the above information identifies that it would not be sufficient to merely heat the base — instead at . least part of the length of the curved upright wall would need to be heated, or perhaps the top of the chamber. This is useful, as it also allows us to produce a vessel for a continuous process. Hence we could use a cylinder as a vessel in which feedstock was continuously introduced at one end, and product removed at the other. The above information helps identify the area of the curved wall of the cylinder which needs to be heated in the reaction portion (the tail end portion may be a cooling portion for reacted feedstock (i.e. product) prior to removal).

We have established guidelines for the configuration of the vessel in terms of its heated surface(s). However consideration needs to be given as to how heat is introduced to initiate a reaction. A range of heating means may be considered, from electrical heating elements, heat exchangers (which may introduce heat from exhausted gases from the process chamber or from other sources), solar energy, etc. For control purposes, electrical heating is perhaps the easiest to control, though valve systems can regulate heat exchange systems. For simplicity of description, we shall (unless otherwise specified) generally refer to an electrically heated system to describe the principles of the invention herein. Ideally the heat source should be distributed over as great an area as possible, rather than just being a point source - thermally conductive elements may be used to achieve this (and in which case the entire conductive element will represent a heating region). This is also reflected in the calculations above. Ideally, the heating should be relatively well distributed rather than a few localised hot spots, though a heat conductive element may act as a heating element by distributing heat from a few localised heat sources.

The amount of energy supplied to the process chamber will depend largely on the nature of the carboniferous feedstock. In initial experimentation the applicant used the following feedstocks, to obtain some baseline values for comparison. We shall use the information from these experiments herein, though note that some types of carboniferous feedstock may require more energy or greater temperature^'s - particularly those with a high moisture content. The feedstocks used in experiments were:

i) cedar wood chips ii) clippings from kiwifruit vines iii) chopped pine branches and including attached pine needles iv) chopped eucalyptus branches and attached leaves v) gorse clippings.

Based on experimentation using a 4 litre feedstock load, at least 50OkJ per litre of heat needs to be applied per litre of reasonably packed feedstock and more preferably within the range 60OkJ to 90OkJ. This is the amount of energy to initiate reaction in a batch process - in a continuous process, energy will be present within the chamber from the typically exothermic reaction of feedstock to product, so maintaining reaction for incoming material may require less externally introduced energy (though depends on process chamber design).

In terms of initiating reaction, sufficient energy should be introduced for the internal temperature of the reaction chamber to reach to 350°C or greater, and ideally 45O⁰C or greater. In initial experiments heat was applied to the vessel to obtain a nominal internal temperature of around 52O⁰C, and then the heating controller ceased applying heat (this was a batch process). At this point the reaction self-propagated and reached a typical peak (4 litre reaction chamber) of around 570 ± 25⁰C. After this the temperature dropped and (for the particular reaction chamber in question) when it had cooled to 450⁰C₅ the reaction to carbon product was considered substantially complete. It should be appreciated that for different feedstocks, different initiation temperatures and parameters would apply and that optimisation of any embodiment for a particular feedstock is recommended. It should also be appreciated that energy applied to the system (i.e. heat) may also be ceased at a certain point when the carbonisation process (typically exothermic) becomes self-sustaining.

The rate at which the energy to initiate reaction is applied can vary. For the trials, the nominal rate was to apply energy at a rate of around 0.8 to 1.5 kW per litre of carboniferous material. This is applied for a reaction initiation period of around 7 to 20 minutes and more ideally for around 10 to 15 minutes - again optimisation for different feedstocks and actual embodiments is recommended. Providing even heating rather than short period high wattage heating may be preferable in terms of a more consistent reaction once initiated. Feedstock has a certain insulating value and rapid heating can overheat areas in the region of the heating surface while more distant feedstock may remain at a much lower temperature — too low for successful reaction. This represents the high temperature differential across the feedstock, mentioned earlier, which current analysis suggests it is best to avoid for efficient carbonisation. Hence consideration will need to be given to optimising the conditions for any embodiment of apparatus according to the present invention, though it is envisaged that this will be well within the skills of a competent worker given the explanations and information given herein.

The vessel in a preferred batch process embodiment is a separate element or liner within the process chamber, facilitating removal of product. It is preferably of a non- porous durable material. Metals may be used for its construction, though so too may ceramics, and other heat resistant materials. Typically there is a heat-resistant ceramic liner, while the outer process chamber may be of a metal (which also facilitates the spreading of applied heat).. The vessel ideally has a closure for its access aperture (for loading and removing feedstock and product) which, quite simply, may be a lid. Removed material is often hot and combustible in air, hence the closure should substantially exclude air though need not be a hermetic seal. The carbonisation reaction typically produces gases which need to be vented. Hence the reaction chamber may comprise some venting apertures, or other methods (such as slightly raising the closure/lid when positioned within the process chamber) may be employed. While this could be vented as waste, there are a number of components which would need to be removed to satisfy environmental pollution controls. Hence, in preferred batch process embodiments, the reaction gases are vented from the process chamber, energy extracted, and then reintroduced back into the process chamber and/or reaction chamber.

Typical reaction gases comprise (near the beginning of the process) methane, nitrogen dioxide and other nitrogen oxides, carbon monoxide, carbon dioxide, sulphur oxides, steam, and other lesser reaction gases depending on the nature of the feedstock. In a preferred embodiment these vented gases are fed directly to a turbine which may drive a generator or perform other work. Consequently work is performed and the temperature of the gases drop. The turbine exhaust is then led to a compressor unit (which may be preceded by an expansion chamber to increase turbine efficiency) where they are compressed to sufficiently high pressure to be reintroduced into the process chamber (which is at a higher pressure). Other techniques than a compressor may be used to reintroduce the cooler, denser gases into the chamber.

Additionally a heat exchanger may be used to extract heat from the gases (typically after the turbine, or as an alternative to the turbine) as another means of extracting energy from the exhaust gases. This exchanged heat may be used in electricity generation, or utilised in other ways.

The cooler reintroduced gases are then re-heated by the exothermic carbonisation reaction and repeat the cycle through the turbine, compressor, heat exchanger, etc. (depending on the embodiment). Carboniferous gases such as methane, hydrocarbons, carbon oxides may, through consecutive passes, also convert to carbon and by-products to increase conversion efficiency.

The present invention also allows for a continuous process (discussed later), though the same general principles regarding exhaust gases produced from the carbonisation process apply. Further efficiencies may be achieved from venting the gases from the later and hotter end (where reaction is well underway) of the process chamber and reintroducing them to the feed end of the chamber. The advantage here is that the reintroduced gases can help pre-heat introduced material. A heat-exchanger which also helps preheat carboniferous feedstock from the exhaust gases can also further increase energy efficiency (reducing power heating costs in a system utilising electrical heating to initiate and/or maintain reaction).

It has been mentioned that a control unit may be used to govern any heating unit and/or the overall process. In preferred embodiments a control unit is used, which may be programmable, hard-wired, software controlled, etc. Typical PLC units such as commonly used as industrial controllers may be used. In principle the control unit may work in a number of ways, and may comprise a multitude of sensors. One possible embodiment is described by way of example, though it should be appreciated that simpler or more complex arrangements may be implemented in different embodiments:

Control Unit Example — batch process

The. control unit typically comprises a PLC able to monitor the temperature within the chamber at at least one point. It may also monitor whether it is safe to initiate reaction - e.g. it may connect to sensors which verify or monitor at least one of: whether the reaction chamber is present (in the case of a removable chamber in a batch process), whether the reaction chamber lid (where present) is in the correct position, whether gates at the feed end of the apparatus are closed, whether vents for exhaust gases are clear, whether any valves for exhaust gases are operational or in the correct position, compressor status, heat exchanger status, various temperatures at points around the exhaust gas system, etc. The control unit may also additional input parameters to be entered for a load, and may optimise its operation in relation to this information. Such input parameters may include: type/category of feedstock, weight of feedstock, load (e.g. full load or an indication of partial load), degree/category of wetness or water content, saved user profiles and favourites, etc.

Once it is safe to start the reaction the control unit typically operates the electrical heating element for the process chamber. The power supplied to the heating element may be calculated based on user parameters or sensed readings (e.g. temperature sensors at different points within the chamber) so that an optimised rate of heating is applied. The temperature is raised to a determined or predetermined point, e.g. 520⁰C, and maintained for a determined or predetermined period of time. The determined period of time may be on the basis on detecting an increase in temperature corresponding to the initiation of a carbonisation reaction - as the PLC will attempt to thermostatically control the heating unit(s) to maintain the predetermined temperature, it could also sense reaction initiation by a drop in required power to the heating unit to maintain the determined temperature. Ideally some degree of user control, or automation, is provided to cater for different types of feedstock and changes in the nature thereof.

Various sensors and methods may be used by the control means to monitor the progress of a carbonisation reaction, and to thus supply the information it may need to assess progression to different steps in the process or to take various actions. For instance, the control means may assess, monitor, or rely on any one or more of: the passing of a predetermined duration, the passing of a predetermined duration from when other criteria (herein) are met, determining when the amount of energy supplied to the chamber heating means to maintain a particular temperature drops or crosses a predetermined threshold or point, measuring the flow of gases and vapours from the chamber and determining when the flow rate crosses a certain predetermined point, and monitoring via sensors for a particular vapour or gaseous by-product indicating when a certain point in the carbonisation reaction, has been reached.

Typically, for a batch process, the control unit may need to do little else rather than to monitor when the temperature within the process chamber has fallen to a temperature indicating completion of the carbonisation reaction, and signalling time for removal of the reaction chamber. However, it may also monitor and control auxiliary equipment, such as the turbine, heat exchanger, compressor, etc. (where implemented). For instance, it may monitor turbine load and efficiency and may control the compressor based on this information to control the rate by which exhaust gases are reintroduced to the chamber. If more energy is removed from the process chamber than the exothermic carbonisation reaction produces, then the reaction may not complete. It may also control valves for venting exhaust gases to maintain a sufficient pressure within the process chamber for optimum reaction. It may also operate safety valves to safely vent exhaust gases in critical situations, though self-actuating safety valves may also be employed. Hence, in more complex embodiments, the control unit may monitor and control a number of parameters to achieve optimum efficiency per load.

In apparatus for a continuous or semi-continuous process, the control unit will typically oversee that the carbonisation process proceeds effectively, and will typically assess various parameters or criteria (such as mentioned previously) before loading new feedstock, removing carbonised product, etc.

Continuous processing shall mean herein, a process in which feedstock is substantially continuously fed into, and removed from, the reaction chamber. Semi-continuous processing shall mean, herein, a process in which discrete lots of feedstock are repetitively fed into, and removed from, the reaction chamber.

In these examples a process chamber is still used but will typically have entry and exit apertures at distal ends of the reaction chamber (though these may be on other faces). Ideally the internal dimensions and configuration are such that feedstock introduced at one end can force existing contents of the chamber through and out of the exit aperture (though gravity may assist or be relied upon). This may mean a substantially constant, or gradually reducing, internal cross section.

While the internal cross-sectional configuration of the chamber can vary in different embodiments, it is typically envisaged that circular or rectangular internal cross- sections will be used for simplicity of construction. Typically one of the faces (or portion thereof in the case of a cylindrical chamber) of the chamber will be heated, though more than one surface (or all of the curved surface of a cylindrical chamber) may be heated. The previous comments on aspect ratio still generally apply for the design of efficient embodiments of continuous process systems. Hence reference is made to the preceding description (though see also next paragraph) on aspect ratio about the relationship between the heating face, and chamber configuration, in preferred embodiments. It may also be advantageous, particularly for upright chamber embodiments, for the^' heating element(s) to be present on more than face of the chamber section through which the feedstock passes. Typically the process chamber may be defined, in a continuous or semi-continuous process embodiment, in two sections: i) the introduction portion, and ii) the reaction portion. The introduction portion is typically where the new feedstock is introduced and heated to a sufficient temperature to initiate and/or maintain reaction within the chamber. Heating means are typically confined to this portion, and this portion should be considered alone^' when determining aspect ratios and heating placement. The reaction portion typically represents that portion of the chamber where carbonisation is underway and should be sufficiently long to enable sufficient time for the carbonisation of travelling feedstock to complete before being expelled from the chamber. The reaction portion may also include a cooling section where heat is removed (by heat exchanger, for example) though the cooling section may be a separate unit from the process chamber, and into which expelled product from the chamber is fed.

In a continuous process chamber the reaction chamber may be excluded as being redundant (it is not required to remove the load from the chamber) though may be present as a protective liner within the chamber.

Typically carboniferous feedstock is fed into one end of the chamber, typically being . forced by suitable feed driving means (discussed later). The process chamber may be oriented upright so that feed into the top of the upright chamber is assisted by gravity.

Heating elements heat the incoming feedstock. This may be progressively - e.g. the heating elements may be disposed or controlled such that there is an increasing and/or decreasing thermal gradient in the applied temperature to the chamber as one travels along it away from the entry aperture. Incoming feedstock may also be heated by vented exhaust gas. Reintroduced gas may be ported into the new feedstock travelling along the chamber. A heat exchanger about the introduction portion of the chamber may also remove heat from the exhaust gases, or from a product cooling section, to preheat the incoming feedstock in the introduction portion.

The control unit will typically control the process, though the more important equipment it controls include the heating element, and the feed driving means. The feed driving means is particularly important as it determines the rate by which the feedstock moves through the chamber. Introduce the feedstock too quickly and product may be expelled before carbonisation is complete. Feed it too slowly and the efficiency of the process is reduced. Hence an operator may rely of predetermined settings, choose the best settings they believe correct from experience, or rely on full or semiautomatic control by the control unit. In the latter cases, temperature sensors along the chamber, and/or of vented gases, can provide an indication of what is happening within the chamber and allow the control unit to take appropriate action - for instance, too cool a temperature at various points (particularly in the reaction portion) may mean the feedstock is moving too quickly.

The control unit will also control the heating elements to provide the minimum (ideally) degree of energy to raise the feedstock to the desired temperature by the time it enters the reaction portion. Considering heat within the chamber emanating from the reaction portion, and any supplemental heating (such as from heat exchangers and exhaust gases) provided, the electrical heating units are typically only acting as a supplemental heating unit.

The control unit may monitor and control other aspects of the process, such as generally discussed in relation to batch process units. Again, the control unit may be simple or sophisticated in design and features, according to user choice.

The feed driving means is essentially any unit capable of forcing and driving feedstock into the process chamber and thereby pushing the contents of the chamber through. The requirements on the feed driving means are typically less in upright chamber embodiments where gravity can assist, and a consequence can be less compacting of the feedstock — while some compaction is desirable, excessive compaction can affect the carbonisation reaction and removal of production gases. Hence upright or inclined process chambers operating in a top-down arrangement possess some potentially realisable advantages.

Various feeding means are known and may be used. Some examples include star valve units (with rotary impellers), screw drives, and piston operated units. Other devices may be considered and used in various embodiments.

Collection of product may typically use an extended or auxiliary cooling chamber through which the product passes and looses heat. Until sufficient heat is lost, the product must be excluded from atmosphere so as to prevent combustion. Final removal may be performed under an inert or reduced pressure atmosphere, or with adequate precautions against possible combustion of a significantly combustible or explosive product (particularly the dust).

DESCRIPTION OF DRAWINGS

Figure 1 are schematic examples illustrating the determination of aspect ratio in a selection of differently configured chambers;

Figure 2 is a. schematic view of an embodiment of _. a batch process arrangement according to the present invention,

Figure 3 is a schematic view of an embodiment of a continuous process arrangement according to the present invention, and

Figure 4 is a schematic view of an embodiment of a semi-continuous process arrangement according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT Aspect ratio

Figures 1 illustrate some possible configurations of reaction chambers, and illustrate how parameters 'd_hs , 'df_s\ and '<4/ are determined.

In figure Ia a cylindrical reaction chamber (1) is shown whose entire base portion (2) is heated. Here, 'd_hs' will be the diameter of the base (internally).

In figure Ib is shown a reaction chamber (3) whose entire base portion (4) is heated, but one dimension (of the base) is longer than the other. Here, 'c4/ is the longest measurable distance between two points within the heated region - the diagonal distance. In the case of a cylinder laid on its side (its rotational axis is horizontal), and where only part of its curved surface is a heated region (here we mean, not that only part of the length (measured along the rotational axis) of the cylinder's curved surface is a heated region, but that the curved surface is not heated entirely about its circumference), then the same principle for determining 'd_hs applies - measure the greatest possible distance between two points on the heated region, ensuring that our imaginary tape measure contacts the curved heated surface along the entire length between the two points.

The same principle would also apply for a cylinder in which the curved surface was heated, for at least part of its Jength, about its entire circumference — i.e. the entire heated region is essentially cylindrical. Here, our imaginary tape measure (still touching the curved surface of the cylindrical heating region) will extend between diametrically opposite points (when viewed along the rotational axis) at opposite ends of the cylindrical heating region. These explanations will help with calculating 'd^' for both closed and non-closed surfaces of varying shapes.

In figure Ic is shown a base (5) for a reaction chamber with a plurality of localised heating regions (6a-d). The greatest measurable distance between points on any two heating represent ^ed_/is' — in this case it is diametrically opposite points on heating regions (6a) and (6d).

Figure Id illustrates a reaction chamber (7) in cross-section and illustrates the normal maximum loading line (8) for contents (9). The internal distance from the base line (being the inner surface of the vessel, on the primary heating surface (10)) to the maximum loading line (8) represents '<%'. In this example, as the internal cross- section of this example is constant, the average load height 'dp of feedstock above the base is ¹A d_/,_s. For alternately shaped bases and vessels (7) with varying cross-sections, various mathematical formulae may be required to calculate ^ζdf_s\ Where a vertical face of a vessel is the primary heating surface, then the distance to the opposite wall may represent 'd_f/ as gravity will typically ensure that the entire volume between the walls is filled. For an upright cylinder with a heated curved wall then 'd_hf can be calculated by the formula "d_hf = diameter x 1 / Cr" where Cr is 1 + the proportion of the circumference of the cylinder (viewed along the rotational axis) about which the heated region extends. Hence, for a heated region extending entirely about the circumference of the cylinder's curved surface, Cr = 1 + 1 = 2, where 1 is the proportion of the circumference with is heated - i.e. 100% which equals 1. If 50% of the circumference is heating region then Cr = 1 + 0.5 = 1.5, where the proportion 0.5 is equivalent to 50%. This general formula can be modified for other shaped closed surfaces.

It should be appreciated that these examples are not intended to be restrictive, and are for assisting the reader understand how the distance parameters are determined. It should be appreciated that in actual embodiments, the reaction chamber may be inclined from the upright so that the heated region (the base in the above description) may not be the bottom surface. Other surfaces, than the base in an upright vessel, may also be heated - essentially any surface, or region thereof, may potentially be a heated surface. Multiple surfaces may also be heated, in which case the surface yielding the greatest value for 'd_h/ should be considered the primary heating surface. Hence, vessels need not be upright, and neither need the lowest surface be heated — there is room for user choice, and the examples of figures 1 merely illustrate the heated surface as the basal surface for simplicity and consistency of description.

Batch Process

A preferred embodiment of apparatus for a batch process is illustrated schematically in figure 2. Referring to this figure there is provided a reaction chamber (200) of a ceramic material with a substantially non-porous coating on at least its inner surface — this may be a glazed ceramic finish. A lid (201) is provided to enable carboniferous feedstock (202) to be loaded and unloaded.

In this embodiment a venting aperture (204) is provided in the lid (201) to allow exhaust gases to exhaust from the vessel (200). Another aperture (205) allows an insertable injection probe. (206) to reintroduce gases from compressor (207).

The reaction chamber is placed within the outer body (210) of the process chamber. This body may be made of metal or other durable substances, though preferably is heat insulated on the outside. A lid (211) is also provided to enable insertion and removal of the reaction chamber (200), though side access embodiments are also possible.

On the inside of the base of the process chamber is an electrical heating element (212) able to heat the internal contents of the chamber - i.e. the. reaction chamber (200) and its contents. Heating is controlled by control unit (214), which also takes readings from at least one thermostatic sensor (215). A typical operating procedure and parameters have been discussed generally, earlier in this specification, though a more detailed description is given below.

Vented gas from port (204) exits via conduit (216) where flow is controlled by valve (217) in turn controlled by the control unit (214). The gases then flow to turbine (218) which is coupled to an electrical generator (not shown), or to another device able to extract work from the exhausted gases.

The gases then pass through heat exchanger (219) which extracts more energy, before the gas enters compressor (207). The compressed gases then pass through one way valve (220) which may also be a flow control valve. The gases are then re-injected (206) into the reaction chamber (200).

The arrangement allows not only for carbonisation of carboniferous feedstock, but also the extraction of further energy from the exothermic reaction via the gases produced in the reaction. These gases may continue to circulate after the reaction stops to help further cool the reaction chamber (200) and contents - the electrical generator may be uncoupled from the turbine so that the heat is primarily removed by heat exchanger (219).

A process method using this apparatus may comprise the following example instructions:

1) load carboniferous feedstock (202) into the reaction chamber (200) and place lid (201) on top;

2) place reaction chamber (200) into process chamber (210);

3) lower lid (211) onto process chamber (210); 4) tighten sealing mechanism (not shown) but which may be clamps or nuts on threaded rods, etc. to hold the lid (211) hi place;

5) open valve (220) from compressor system to chamber and pressurise chamber. Typically there will be gas in the turbine compressor system from previous batches (particularly if there is also an expansion chamber as part of the system), though more gas will typically be produced from the carbonisation process and the pressure will gradually increase (as well as from an increase in temperature). Alternatively a separate chamber (not shown) may be used to store gas - typically to reduce pressure in the process chamber (210) at end of the carbonisation reaction, so the chamber (210) can be safely opened. However it is envisaged that any volume for storing gas is most likely to be part of the turbine/heat exchanger pprtion of the apparatus.

6) close the valve (220) against back flow;

7) start heating process and heat to at least 450⁰C for typical biomass such as described in bench-top trials of the applicant - this will ideally be optimised for a particular feedstock;

8) monitor pressure and once pressure exceeds a nominated value, the valve (217) opens and flow through the turbine and heat exchanger portion of the system can occur, such as described in the specification. For small scale operations, the turbine/heat exchanger/compressor arrangement may be omitted and instead replaced with a closed loop, or a pressure vessel (not illustrated) or tank to accommodate gas from the process chamber (210) (see step 5 above);

9) monitor temperature and wait until temperature is below 350⁰C, signalling end of carbonisation reaction for most feedstocks.

10) release gas from the process chamber (210) into the turbine/heat exchanger/compressor arrangement, or into a pressure vessel.

11) confirm pressure is safely reduced in process, chamber and open sealing mechanism for lid (211);

12) empty product from insert into a closable, thermally resistant vessel;

13) seal pot and let cool to less than 100⁰C.

Continuous Process

Figure 3 illustrates an embodiment of apparatus for the continuous processing of carboniferous product into carbon product. The chamber (300) comprises an outer liner of a heat insulating material. Within the outer liner is an inner liner (300a) which is non porous and optionally heat conductive to facilitate the inward transfer of heat from heating sources. There is present an introduction portion (301) into which new feedstock (not shown) is introduced, and a reaction portion (302) in which the bulk of the carbonisation reaction occurs. Feed driving means (304) comprising a star or screw drive receives bulk feedstock from a feed hopper (305). This may be replenished by conveyor (not shown). The feedstock is driven at a controlled rate (determined by control unit (303)) into the introduction portion (301). The feedstock is initially heated by heat exchanger (306) which receives heated production gases from turbine (307). Turbine (307) may be coupled to an electrical generator (not shown). These gases, after passing through heat exchanger (306) are compressed (310) and reintroduced through a port (309) into the introduction portion (301).

The feedstock is next heated by heat exchanger (308) as it passes down through the chamber. This exchanger (308) receives heat from circulating coolant from the cooling section (312). A heat exchanger (314) removes heat from the contents within the' cooling section (312) and coolant is circulated by pump (315).

Heating elements (315) controlled by control unit (303) then further heat the feedstock as it passes down through the introduction portion (301) to a predetermined temperature — e.g. 500⁰C or thereabouts. By this stage reaction initiation will be occurring and the feedstock travels through the reaction portion (302) where the carbonisation process completes.

Eventually product exits from the reaction portion where it enters cooling section (312) previously described above. Exiting product (arrow 320) may then be fed to further cooling and/or collection means.

Some further notes on variations that may be exercised in a continuous process are as follows:

Material can loaded by either Front end loader or other mechanical device into a feed box or hopper, depending on the drive unit (304). A multiple compartment feeder may be used, in place of the hopper (305) or between the hopper (305) and drive unit (304). Each compartment has a feed (e.g. top) opening for loading feedstock, and a release (e.g. bottom) aperture for releasing feedstock into a drive unit (304). As one compartment is being filled, the other has a closed feed opening opened release opening, such that feedstock falls from the compartment into feed drive unit (304). The feed drive unit (304) may be a compacting funnel, where a mechanism (such as a piston) compacts and pushes the feedstock into the introduction portion (301).

The cooling section (312) after the reaction portion (302) may comprise a two way hatch system which splits discharged product to one or more product conditioning boxes (not shown), where previously cooled product is reintroduced to optimise carbon yield (particularly if graded cooled product is reintroduced) and to more quickly cool the most recently discharged product - so it can most quickly be collected from the cooling section (312) without risk of combustion.

If excess gas pressure is produced from the process chamber (301, 302) during carbonisation, vented gas (to reduce pressure) can be run through the stored product (which acts as a carbon filter) or product in the cooling section (312). .

Semi-continuous process

Figure 4 schematically illustrates an embodiment of apparatus for a semi-continuous process. Here, raw feedstock (for this example, partially shredded tyres - whole tyres can be used, though shredding can increase packing efficiency) (400) is fed into a hopper (401). A control valve (402) at the base allows lots of feedstock to fall from the hopper (401) into, an introduction chamber (403). This may be preheated by units (404) that transfer heat from later in the process - e.g. connection (A).

A ram (405) operated piston (406) is used to compact and move feedstock along the introduction chamber (403) towards the reaction chamber (407). A gate (408) separates the reaction chamber from the introduction chamber (403) when feedstock is not being forced into the reaction chamber (407) by virtue of the action of the piston (406).

On alternate faces of the reaction chamber (rectangular in cross-section) are electrical heating elements (409). These are rated at 12OkW under full power for a reaction chamber approximately Im wide and 0.2m high and holding approximately 1 cubic metre of feedstock. These elements (409) raise the internal temperature of the reaction chamber to within the inclusive range of 400⁰C to 55Q°C (typically) to initiate the carbonisation reaction. After the initiation temperature is reached, the power input is reduced to maintain the temperature of the reaction chamber within the aforementioned temperature range. As the carbonisation reaction is typically exothermic, the amount of energy applied will eventually fall to zero, though input may still be required will biomass which is quite wet and green.

A ceramic liner of heat resistant material (411) lines the reaction chamber (407) and also the cooling chamber (410).

After a predetermined reaction time, or when certain monitoring criteria have been met, a fresh load of preheated feedstock is forced into the reaction chamber (407) by the action of the piston (406). This forces the carbonised (or partially carbonised) mass from the reaction chamber (407) into the cooling chamber (410). In here, carbonisation may still progress and cooling begins. Heat may be extracted (412) such as by collecting gases and vapours (including steam) released as part of the carbonisation process. These may be further processed (414) such as by condensing and collecting (415) various fractions present (e.g. water, petrochemicals and hydrocarbons, etc.).

At the end of the cooling chamber (410) a trapdoor (417) drops the carbonised mass onto a screening conveyor (419). A rotating roller (418) can help crush the carbon so it falls through the screen (419) for collection (420).

Foreign material (e.g. the steel belts from tyres) are collected (421) at the end of the conveyor (419).

Typically the carbon is not exposed to air until it has cooled sufficiently (to avoid combustion), and thus there may be additional cooling prior to screening.

It is envisaged that the embodiment of figure 4 may still utilise a turbine and generator as per the continuous process of figure 3, though for clarity this has been omitted from figure 4. The heated gas from the chamber contains considerable energy, which may be harnessed to drive a turbine and generator so as to produce electricity. This electrical energy may be stored for use in the next heating cycle, reintroduced into the power grid, and/or may be required to supplement the power supplied to the heating elements (409) if required at that time. Such a turbine/generator may be positioned intermediate the gas connections 'A' (in figure 4) or prior to condenser (414). As should be appreciated, other means may also be used to extract energy produced by the carbonisation reaction. For instances, such heat may be used to further distil and fractionate (or purify) condensibles (415) collected from the condenser. Heat exchangers (not shown for clarity) may extract energy for use elsewhere or in external equipment. Heated gas may also be used to assist the drive of conveyor (419) or roller (418) etc.

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 spirit or scope of the present invention as described herein.

It should also be understood that the term "comprise" where used herein is not to be considered to be used in a limiting sense. Accordingly, 'comprise' does not represent nor define an exclusive set ^'of items, but includes the possibility of other components and items being added to the list.

This specification is also based on the understanding of the inventor regarding the prior art. The prior art description should not be regarded as being authoritative disclosure on the true state of the prior art but rather as referencing considerations brought to the mind and attention of the inventor when developing this invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE:

1. Carbon producing apparatus for the production of a carbon product from a carboniferous feedstock, said carbon producing apparatus comprising a process chamber in turn comprising:

- a reaction chamber capable of containing said carboniferous feedstock during its conversion to a charcoal product, chamber heating means capable of increasing the internal temperature of the process chamber to in excess of 35O⁰C,

- control means for controlling chamber heating means so as to increase and maintain the internal temperature of the process chamber to in excess of 350°C for the conversion of carboniferous feedstock to a carbon product.

2. Carbon producing apparatus as claimed in claim 1 in which the relationship between the reaction chamber and chamber heating means being such that, the chamber heating means provides one or more effective heated surface areas acting within the reaction chamber in which 'd_hs' represents the longest dimension of either a said effective heated surface area, or the length spanning and including effective heated areas associated with a face of said reaction chamber; the relationship between the reaction chamber being further defined such that the reaction separation distance, comprising the average distance of any loaded carboniferous feedstock in said reaction chamber to an effective heated surface area (as defined in the specification) within the reaction chamber, is less than 1.5 times 'dhs'-

3. Carbon producing apparatus as claimed in claim 2 in which the reaction separation distance is less than or equal to 1.0 times 'di_ιs'.

4. Carbon producing apparatus as claimed in either of claims 2 or 3 , in which said reaction chamber has a length 'I_n,' and is of substantially constant cross-section along its length 'I_n,'.

5. Carbon producing apparatus as claimed in claim 4 in which there is an effective heated surface area on a face of the reaction chamber which is substantially perpendicular to length 'I_n,'.

6. Carbon producing apparatus as claimed in either claim 4 or claim 5 in which there is an effective heated surface area on a face of the reaction chamber which is substantially parallel to length 'I_n,'.

7. Carbon producing apparatus as claimed in any one of claims 4 through 6 in which there are provided an effective heated surface area or areas whose total area comprises at least 80% of average cross-sectional area of the reaction chamber.

8. Carbon producing apparatus as claimed in any one of claims 4 through 7 in which the cross-sectional diameter of the reaction chamber is substantially constant along dimension 'I_n,' , and the total area of heated surface area(s) associated with the reaction chamber comprises at least a proportion of the internal surface area of the reaction chamber calculated by (2 / 'd_g/ + 2) * 100 (as a percentage), and wherein 'd_m' represents the average cross-sectional diameter or span of the reaction chamber along dimension 'I_n,', said proportion being 18% or greater.

9. Carbon producing apparatus as claimed in any one of the preceding claims in which at least the internal surface of the reaction chamber is substantially non- porous.

10. Carbon producing apparatus as claimed in any one of the preceding claims in which at least the internal surface of the reaction chamber is made of a ceramics material.

11. Carbon producing apparatus as claimed in any one of the preceding claims in which a heating element may comprise one or more members of the group comprising: electrically powered heating elements, conduits conveying heated material, and conductive elements conveying heat from a heat source.

12. Carbon producing apparatus as claimed in any one of the preceding claims in which the reaction chamber has at least two access apertures, one for the introduction of material into the reaction chamber, and one for the removal of material from the reaction chamber.

13. Carbon producing apparatus as claimed in claim 12 in which the two access apertures are on opposing sides of the reaction chamber.

14. Carbon producing apparatus as claimed in claim 12 in which the access aperture for the introduction of material into the reaction chamber is connected to an a feed system for introducing material into said reaction chamber, said feed system comprising one or more of: an automated feed system, a continuous feed system, and a semi-continuous feed system feeding discrete lots of feedstock in a repetitive manner:

15. Carbon producing apparatus as claimed in claim 14 in which at least one of the following parameters of the feed system can be altered: feed rate, feed timing, period of operation.

16. Carbon producing apparatus as claimed in claim 14 or claim 15 in which the feed system introduces feedstock into an introduction portion, and which action further pushes existing feedstock within the introduction portion into the reaction chamber.

17. Carbon producing apparatus as claimed in claim 16 in which feedstock within the introduction portion is preheated by one or more of the following methods:

• 'radiant heat from the .reaction chamber, heat conducted from the reaction chamber, waste heat recovered from the carbonisation process, electrical heating elements, heat produced from the combustion of combustible gases recovered from the carbonisation process, and heat from gases and vapours recovered from the carbonisation process.

18. Carbon producing apparatus as claimed in any one of claims 12 through 17 in which the access aperture for the removal of material from the reaction chamber is connected to a carbon product removal system.

19. Carbon producing apparatus as claimed in claim 16 in which the action of the feed system pushing feedstock into the introduction portion, and subsequently forcing existing material within the introduction portion into the reaction chamber, also forces material within the reaction chamber into a cooling section.

20. Carbon producing apparatus as claimed in claim 19 in which operation of said feed system is controlled by the control means such that feedstock is forced from the reaction chamber to the cooling section prior to full conversion to a charcoal product, and in which further carbonisation occurs within the cooling section as a consequence of the residual heat of the partly carbonised feedstock removed from the reaction chamber.

21. Carbon producing apparatus as claimed in claim 19 or claim 20 in which material forced from the reaction chamber into the cooling section acts on existing material in the cooling section and forces it into product collection means.

22. Carbon producing apparatus as claimed in claim 20 or claim 21 in which said apparatus substantially excludes air from coming into contact with feedstock and/or product within or removed from the reaction chamber.

23. Carbon producing apparatus as claimed in any one of the preceding claims in which there is a heat exchanger associated with said cooling section, and which recovers waste heat from the cooling section.

24. Carbon producing apparatus as claimed in any one of the preceding claims in which feedstock is introduced ultimately into the reaction chamber by an arrangement comprising at least one of the following mechanisms: a piston arrangement, a rotating screw arrangement, and a rotating chamber arrangement.

25. Carbon producing apparatus as claimed in any one of the preceding claims in which the control means monitors the temperature within the reaction chamber, and initiates the introduction of fresh feedstock into the reaction chamber by feedstock drive means when specific criteria are met, said criteria comprising one or more of: a predetermined duration, a predetermined duration from when other criteria (herein) . are met, when the amount of energy supplied to the chamber heating means to maintain a particular temperature crosses a predetermined threshold or point, measuring the flow of gases and vapours from the chamber and determining when the flow rate crosses a certain predetermined point, and monitoring via sensors for a particular vapour or gaseous by-product indicating when a certain point in the carbonisation reaction has been reached.

26. Carbon producing apparatus as claimed in any one of the preceding claims which includes plumbing for the removal of exhaust gases and collecting this in one or more fractions.

27. Carbon producing apparatus as claimed in claim 26 in which a fraction of the exhaust gases are reintroduced directly or indirectly into the reaction chamber.

28. Carbon producing apparatus as claimed in claim 27 in which a compressor is used to reintroduce gaseous materials into the reaction chamber.

29. Carbon producing apparatus as claimed in any one of the preceding claims in which includes plumbing for removing exhausted gases from the carbonisation process, and which gases are used to drive a turbine which is connected or connectable to an electrical generator.

30. Carbon producing apparatus as claimed in claim 1 which comprises an elongate process chamber of substantially constant cross-section, and which chamber includes an introduction portion followed by a portion comprising the reaction chamber and followed by a cooling section; there being feed means capable of forcing an introduced supply of feedstock into the introduction portion intermittently, and which action forces material within the process chamber progressively therethrough; and wherein the chamber heating means of the reaction chamber is capable of raising the temperature of material within the reaction chamber to a temperature within the inclusive range of 400° to 55O⁰C; and in which the longitudinal length of the reaction chamber portion of the process chamber is equal to or greater than the average cross-sectional diameter or span across the reaction chamber.

31. A carbon product produced from carbon producing apparatus as claimed in any one of the preceding claims.

32. A method for producing a carbon product comprising the use of carbon producing apparatus as claimed in any one of claims 1 through 30, said method comprising introducing carboniferous feedstock into the reaction chamber, and raising the temperature in excess of 350⁰C for a period of time.

33. A method for producing a carbon product as claimed in claim 32, in which the amount of energy introduced to carboniferous feedstock within the reaction chamber, measured per litre of carboniferous material, is at least 500 kJ over a period within a reaction initiation period in the range of 3 to 20 minutes inclusive.

34. A method for making a carbon product as claimed in claim 32 or claim 33 in which the carboniferous feedstock comprises tyres.

35. A method as claimed in claim 34 which includes removing and recovering hydrocarbon and/or condensible gaseous by-products from the carbonisation process.

36. A method as claimed in claim 34. or claim 35 in which carbonised product is screened to remove non-carbon impurities in the product obtained from the reaction chamber.

37. A carbon product obtained from a method as claimed in any one of claims 32 through 36.