TECHNICAL FIELD

The present invention relates to pyrolytic and/or thermochemical conversion reactions, apparatus therefor and related methodology. Within the scope of the present invention are not only the methods of preparing certain compounds

(carbohydrates and/or hydrocarbons or at least complexes thereof), the compounds or complexes thus prepared but also apparatus capable of performing such a method.

The invention also includes the use of any such methodology and apparatus within expanded plant procedures whether involving add-on of the methodology to some existing plant or not which produces at least one of the feed materials required (for example, a Convertech system as hereinafter defined). The exploitation of the invention also envisages recycle modes of operation whether any recycle is of feed streams or heat enhanced liquids and/or gases. The invention also considers sequential and/or parallel operation ofthe methodology.

BACKGROUND ART

In our US Patent Specification Nos. 5,328,562 and 5,454,911 (equivalents EUR90304922.9 and AUS632121 (and others)} there is disclosed a procedure whereby organic materials (and particularly lignocellulosic materials) can be subjected, after start up conditions have been achieved, to high temperature and high pressure hydrolysis whilst entrained in steam, such hydrolysis occurring at saturated steam conditions, prior to flashing off ofthe at least partly hydrolysed material into a super heated steam entrainment system to provide a substantially hydrolysed and dry product which can, if desired, be delivered in a steam environment for downstream processing or which can be harvested therefrom. The availability ofthe product in a steam environment which allows reduction ofthe solids to fine particle sizes while still in a safe steam environment does engender the prospect of the on-

feed of such materials into (by way of example) gas turbines or the like for combustion or into refinery systems for chemical conversion by pyrolysis.

In our New Zealand Patent Specification No. 248884 and its equivalent PCT/NZ94/00101 there is disclosed systems whereby a pre-wash procedure or procedures essentially de-ashes the product to be formed. The full content of the aforementioned patent specifications is hereby incoφorated by way of cross reference. Such cross references will show the energy advantages of such a procedure over most if not all other procedures for the treatment of lignocellulosic materials prior to the use thereof either as a fuel or for downstream processing, e.g.; to make self curing boards or as a source of chemicals. The present mvention is directed to pyrolytic and/or thermochemical conversion reactions which can usefully (but not necessarily) be combined with the Convertech process in any of its modes as previously disclosed or which can if desired by used with any alternative source of an organic material to yield useful carbohydrate and/or hydrocarbon materials usually in the form of complexes.

DISCLOSURE OF THE INVENTIONS

In a first aspect the invention consists in a method of preparing carbohydrate complexes (or a carbohydrate complex) and/or hydrocarbon complexes (or a hydrocarbon complex) from a particulate organic material or organic materials [preferably the principles of which are ultra-fast heating ofthe particulate organic materials) by way of admixture with a (preferably gaseous) heating medium and without having the substantial recourse to their entering into contact with other solid materials (such as the walls of a vessel, and/or other impinging particulate solids such as sand), optional admixture of said organic materials) with reactive (preferably) gaseous reagents (such as oxidisers and/or hydrogen donors), and subsequent cooling ofthe resulting products, wherein preferably the ultra-fast operation is achieved by way of suitably

designed nozzles as described below, and wherein ultra-fast refers to the reaction and cooling residence times required to minimise the production of unwanted residual products (such as char or carbon dioxide) and maximise the production of valuable products (such as methane, light and heavy hydrocarbons, and other commercially valuable carbohydrates) as is known to those skilled in the art of pyrolysis and thermochemical conversion of organic materials and is further described below], and which comprises the steps of

(i) preparing a dense mixed phase of organic particulate materials entrained with a gas (such as steam) and with the entraining gas being preferably less than 1% by weight of the total dense mixed phase and where the entraining gas preferably does not react with the organic particulate materials under the chosen operating conditions;

(ii) mixing the organic material(s) as dense mixed phased entrained particulate material(s) with a (preferably gaseous) heat transfer medium which is at an elevated temperature and allowing pyrolytic and/or thermochemical conversion to occur at elevated pressure(s) and temperature(s) to produce an oil/gas phase, and (iii) rapidly reducing the temperature of the oil/gas phase from step (ii) without any substantial mixing with a coolant to produce the carbohydrate comρlex(es) and/or hydrocarbon complex(es), and

(iv) optionally, collecting and separating the preferably substantially cooled products from step (iii) [including any residual solids (such as char)], wherein steps (ii) and (iii) are performed in a total time of less than or equal to 10 seconds, and wherein operating parameters at least including the choice of organic material(s), the choice of heat transfer medium, the ratio of flows and temperatures of the dense mixed phase entrained organic particulate material(s) to heat transfer medium and the timing of the

steps (ii) and/or (iii) govern the product(s) yielded.

In a second aspect the invention consists in a method of preparing carbohydrate complexes (or a carbohydrate complex) and/or hydrocarbon complexes

(or a hydrocarbon complex) from an organic material or organic materials which comprises the steps of (i) preparing a dense mixed phase of organic particulate materials entrained with a gas (such as steam) and with the entraining gas being preferably less than 1% by weight of the total dense mixed phase and where the entraining gas preferably does not react with the organic particulate materials under the chosen operating conditions; (ii) mixing the organic material(s) as dense mixed phased entrained particulate material(s) with a (preferably gaseous)

(a) heat transfer medium at an elevated temperature which is not an oxidizer of the organic material(s) and/or

(b) heat transfer medium at an elevated temperature which is an oxidizer ofthe organic material(s) and allowing pyrolytic and/or thermochemical conversion to occur at elevated pressure(s) and temperature(s) [together with any limited oxidation that may be allowed by the presence of any heat transfer medium that is a said oxidiser] to produce an oil/gas phase, and

(iii) rapidly reducing the temperature of the oil/gas phase from step (i) without any substantial mixing with a coolant to produce the carbohydrate complex(es) and/or hydrocarbon complex(es), wherein steps (ii) and (iii) are performed in a total time of less than or equal to four seconds, and

(iv) optionally, collecting and separating the substantially cooled products from step (iii), [including any residual solids (such as char)]. Preferably said dense mixed phased entrained particulate material(s) is dry

organic material(s) that is or has been sufficiently uncompacted and/or fluidised in a gas environment to allow its rapid injection into a mixing zone, with the particles preferably being of a sufficiently small size for the dense mixed phase to be easily created (this will vary with the nature ofthe organic materials being processed such as Convertech' s Cellolig, pulverised lignite, peat of coal), and with a minimum amount ofthe entrainment gas used.

Preferably the mixing is by turbulent mixing brought about by mutual impingement of the feed streams, i.e.; that of the dense mixed phase entrained particulate material(s) and that ofthe heat transfer medium [and that of any optional oxidizers.] such as can, for example, be achieved through suitable concentric nozzles. Preferably said heat transfer medium is a gas and/or, optionally, liquid.

Preferably said organic material(s) have an average mesh size of less than one millimetre.

Preferably said organic material(s) feed material is at an elevated temperature, (i.e.; above ambient temperatures) at the time said mixing. Preferably said mixing is achieved solely by a turbulent mutual impingement of feed streams as or prior to their entering a pyrolytic and/or thermochemical reaction chamber.

Preferably the organic material(s) is injected for impingement with the heat transfer medium at a speed less than that ofthe heat transfer medium. Preferably said organic material is a substantially dry output material of the

Convertech process, i.e.; an organic material (preferably lignocellulosic, or derived from coal, lignite or peat) that has been subjected to at least substantial hydrolysis at saturated steam conditions and thereafter has been steam dried in superheated steam conditions, both the saturated steam and superheated steam conditions being at elevated pressures and elevated temperatures.

Preferably when the organic material is not a dry hydrolysed material from a Convertech process as hereinbefore defined, is either a fossilised material (for example, lignite or other coal), peat, or the like or is a non fossilised material such as,

for example, derived from Municipal Solid Waste (MSW)

Preferably the organic material(s) is supplied at up to 33 bar and in a temperature range of from 230°C to 280 °C (for example about 255 °C). Preferably the particulate product is supplied at about 20 bar. Preferably said heat transfer medium is at a temperature above 600°C. Preferably said heat transfer medium is supplied at a temperature of between

800°C and 2000°C.

Preferably step (ii) is performed in a mixing and/or reaction chamber similar to that which may be used as a rocket engine or substantially as herein described with or without reference to any ofthe accompanying drawings. Preferably the pyrolytic and/or thermochemical conversion is allowed to occur within a temperature range from about 600°C to about 1200°C and at a pressure between about 20 and 300 bar.

Preferably the pyrolytic and/or thermochemical conversion is allowed to occur in operating conditions of about 760 °C between 50 and 150 bar. Preferably the duration of each of steps (ii) and (iii) is less than one second.

Preferably the product is a carbohydrate or hydrocarbon complex with a calorific value greater than 5 MJ/ m3 at STP.

Preferably said organic material(s) has been at least substantially de-ashed prior to step (i). Preferably in some embodiments an oxidiser is mixed in as said heat transfer medium, or as part of said heat transfer medium or optionally in addition to said heat transfer medium.

Preferably any said oxidiser material is introduced at an elevated temperature.

Preferably any said oxidiser material is selected from the ultimate products or by-products from the process (such as CO ₂ ) or acquired independently as a separate feedstock (such as pressurised 0 ₂ ), the oxidiser being used to increase the temperature in the reaction chamber and/or orient in a desired way chemical reactions taking place in the chamber.

Preferably the temperature reduction step (iii) leads to temperature reduction to below 600 °C.

Preferably said temperature reduction is to a temperature below 500 °C. Preferably the temperature reduction is of the order of about 300°C within a time under 50 milliseconds. Preferably step (iii) is performed in a conductive conduit through which the oil/gas phase of step (ii) moves at a super sonic speed, that is at a speed faster than what the speed of sound would be within said conduit, at the operation temperature and pressure, and within the gases and vapours flowing through the said conduit during operation, for example, ofthe order of about 340-400 metres per second. Preferably heat conductively taken through the conduit (preferably tubular) is ducted away as an increase of temperature and/or pressure of a working or coolant fluid.

Preferably said working or coolant fluid is water and/or steam. Preferably step (ii) is performed in a way akin to that of a rocket reliant on a binary feed and step (iii) is effected using a Velox type tubular system as hereinafter defined.

Preferably the method is performed in parallel or in series after a process which produces an appropriate organic material or organic materials as a feed material. Preferably a method as previously setforth is performed in series with appropriate recycle of any appropriate feedstocks and/or product outputs and/or carrier media, and/or heat.

In a third aspect the invention consists in apparatus suitable for use in performing a method as previously defined said apparatus comprismg means of creating a dense mixed phase by admixing a minimum amount of a carrier fluid, preferably in a gas phase, to organic particulate matter of sufficiently small mesh size, means defining a rocket type reaction zone having inlet nozzles for

(a) said organic material(s) and

(b) said heat transfer medium (and optionally (c) any oxidizer) so as to cause (I) inlet stream mutual impingement and thus turbulent mixing and ultra-fast heat transfer, and (II) to allow at least some pyrolytic and/or thermochemical conversion before egress from such zone, and tubes or conduits (hereafter "tubes") subjected to a working fluid to take heat therefrom by a non mingling heat transfer from the oil/gas phase which allows the movement of the oil/gas phase from the mixmg/pyrolytic conversion zone(s) to a harvest and/or downstream processing stage, the apparatus being operable whereby (I) and (II) causes an over speed of sound flow of the cooling oil/gas phase through said tubes, said speed of sound being defined as the speed sound would travel within said tubes, at the operating temperature and pressure, and within the gases and vapours flowing through the said tubes during operation.

Preferably said apparatus includes means defining a harvest and/or downstream processing zone.

Preferably the resulting products oil/gas phase and any entrained residual solids (such as char) are collected at the exhaust of the cooling tubes by means of a suitable chamber feeding into a suitable separation device such as of a cyclonic nature followed with buffer storage vessels and de-pressurising valves. In still a further aspect the present invention consists in a carbohydrate and/or hydrocarbon material or complex produced by a method in accordance with the present invention and/or using apparatus in accordance with the present invention.

In still a further aspect the present invention consists in, in combination, a

Convertech type process as previously setforth and a method or process in accordance with the present invention as previously defined dealing with the output materials from the Convertech procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred forms ofthe present invention will now be described with reference to the accompanying drawings in which

Figure 1 is a simplified diagrammatic view ofthe main steps of one aspect of the present invention, Figure 2 is a similar diagram to that of Figure 1 but showing more detail and preferment options,

Figure 3 presents in a conceptual form the preferred apparatus construction,

Figure 4 is a diagrammatic view by way of example, of how the invention can be embodied into an expanded process converting ligno-cellulosic plant materials (such as farm or forestry residues, or dedicated crops) into a range of valuable products,

Figure 5 is a diagrammatic view, by way of example, of how the invention can be embodied into an expanded process converting lignite into a range of valuable products, Figure 6 describes in a diagrammatic fashion, and by way of illustration, the proven ultra-fast heat transfers that can be achieved through concentric nozzles derived from techniques used in rocket engines as found in the literature on coal conversion, and

Figure 7 describes in a diagrammatic fashion, and by way of illustration, the proven ultra-fast heat transfers that can be achieved through supersonic nozzles as found in the literature on Velox tubes.

Figure 1 stresses the overall short residence time the invention enables. The dense mixed phase organic particulate material is preferably dry and the heat transfer medium is preferably a gas. The configuration of the system is such that the mixing of heat medium and dense mixed phase, and resultant heat transfer take place within milliseconds. As the heat transfer takes place, the pyrolysis or thermochemical conversions start occurring and continue as the feedstocks move through the front part ofthe device, the reaction chamber, and towards the ultra-fast cooling step. This

latter step is achieved preferably without admixture of the products with a cooling fluid. This avoids contamination of products, and substantially reduces environmental impacts, while significantly improving product quality and value.

Figure 2 elaborates upon the general principles presented in Figure 1 by specifying the preferred operation ranges for the key pressure, temperature and residence time parameters. It also indicates the optional use of an oxidiser reactant that can be injected in the reaction chamber jointly with the two other streams, the function of which can be to boost and regulate the desired temperature, and/or to shift chemical reaction in the desired direction.

Figure 3 describes the preferred apparatus configuration. In order to maximise heat transfer efficiency and plant capacity, this would have more than one reactor nozzle to inject the dense mixed phase and heat transfer medium. The diagram present the preferred configuration in generic terms only. Each component can be implemented in a variety of ways provided these meet the operation specification described earlier and below. For example, the flow ofthe cooling fluid, preferably water and steam, around the supersonic nozzles can be achieved through various forms of ducting, and can be implemented in modular fashion to accommodate different requirements in terms of residence time and capacity.

Both Figure 4 and Figure 5 present preferred generic plant configurations by way of example. Figure 4 describes the schematic structure of a biomass fractionation and refining plant that embodies the previous patent specifications for the Convertech process and combines them with a preferred mode of implementation for the present invention. In the front part the cornminuted biomass undergoes a series of chemical transformations through a sequence of front end wash that partly de-ashes the biomass, steam extraction of volatile compounds and hydrolysis of the hemicellulosic fraction in modules one and two. intermediate was to complete the de-ashing and extraction of furfural from the pressurised was steam, reheat ofthe lignocellulosic solids in module three, partial hydrolysis of cellulose and lignin into low molecular

weight forms in module 4 and final drying with super heated steam in module five.

In the train of five module the particulate materials are entrained in suspension in a steam flow. Each module is operated at different temperatures and pressures to achieve the required chemical transformations. The materials are transferred across different pressure zones preferably through Interlocks, proprietary rotary valves designed by Convertech, and the object of separate patent specifications. At the exhaust from module five the resulting lignocellulosic material is in pulverulent form, substantially dry, and held preferably above 20 bar and 200°C. It can optionally undergo further comminution prior to being converted into a dense mixed phase by injection of a minimum of a non reactive dry transport gas (such as steam). The dense mixed phase is injected in the Pyrolytic Reactor described in Figure 3.

The heat transfer medium is preferably an admixture of recycled gases separated from the exhaust gases from the Pyrolytic Reactor, optionally combined with hydrogen from a separate hydrogen plant with an optional admixture of oxygen or air (preferably oxygen in order to avoid the formation of NO _x contaminants). The admixture of oxygen is used to achieve and maintain the required temperature for the heat transfer medium through a partial combustion of the hydrogen. Alternatively a partial combustion ofthe exhaust products from the Pyrolytic Reactor (such as char) can be used to achieve and maintain the required temperature for the heat transfer medium. The main fraction of the products separated from the exhaust from the Pyrolytic Reactor are supphed to conventional upgrading and storage units similar in concept to that used in oil refineries and/or to power generation plants such as using high efficiency aeroderivative gas turbines. The steam produced by the cooling function of the Pyrolytic Reactor is supphed to a steam turbine for further power generation while the exhaust heat from both gas and steam turbines is recycled to the train of five Convertech module through conventional heat recovery boiler and exchanges to heat the primary heat (that supplies heat to modules four and five), and produce the hot water required for the two washes. The steam produced by the fifth module (drying stage) is also recycled and is used jointly with the exhaust heat from

the turbines to heat the secondary heater that supplies heat to modules one, two and three.

Figure 5 presents a similar preferred application in the case of lignite processing whereby the lignite is first pulverised and partially de-ashed by washing, then undergoes upgrading and drying in the series of five Convertech modules and intermediate wash. The upgrading involves further de-ashing, decarboxylation and condensation reactions. The implementation of the pyrolytic reactions in the preferred apparatus described in

Figure 3 is similar to that described for biomass in Figure 4 however, in the case of lignite, owing the larger capacity ofthe plant, the preferred implementation of the methods would involve using some of the co- products to prepare the hydrogen used as heat transfer medium. The Pyrolytic reaction can be conducted optionally to manufacture a substitute natural gas, essentially a mixture of methane (over 90%) and some carbon monoxide, or alternatively, to maximise the production of oil products (such as light oil, aromatic naphtha, and heavy oil fraction) that can subsequently be refined and upgraded through conventional oil refinery technology.

The physics principles undeirjinning this invention are well known and although they have never been used before as indicated in the present methods and apparatus they have been so individually and separately in different apparatus and methods which have been used commercially and in research project in the past, thus proving the feasibility and practicality ofthe present invention.

Figure 6 and Figure 7 are provided, by way of example, of such prior embodiments of the physics principles used in the present invention.

Figure 6 demonstrates the extremely fast heat transfers achieved in Velox boiler tubes as described in Meyer, A, "The Velox Steam Generator" in Mechnical

Engineering, August 1935.

Figure 7 presents in diagrammatic fashion a modified rocket engine used in experiments to react pulverised coal with hydrogen as described in Ubhayakar, S.K.,

5 Oberg, C.L., Cobms, L.P., and Friedman, J., "Rocket Reactor Technology Applied to Coal Conversion" in Advances in Coal Utilization Technology, Symposium Papers, May 14-18, 1979, Louisville, Kentucky, Institute of Gas Technology Chicago, Illinois, USA.

l o SCIENTIFIC AND TECHNOLOGICAL EXPLANATION

This invention proposes integrating a number of known phenomena from the fields of physics and chemistry to achieve and control the operating conditions that are required for the ultra-fast processing of particulate organic feedstocks at high pressure and temperature.

15 The principles of the invention are the ultra-fast heating and cooling of particulate organic materials (with their optional admixture with reactive preferably gaseous reagents such as oxidisers, and/or hydrogen donors), and resulting products without having substantial recourse to the feedstock materials entering into contact with other solids (such as the walls of a vessel and/or other impinging particulate 0 solids such as sand) for the heating and without having substantial recourse to direct admixture with cooling fluids for the cooling, this being achieved by way of suitable designed nozzles as described below. Ultra-fast refers to the reaction and cooling residence times required to minimise the production of unwanted residual products (such as char or carbon dioxide) and maximise the production of valuable products 5 (such as methane, light and heavy hydrocarbons, and other commercially valuable carbohydrates) as is known to those skilled in the art of pyrolysis and thermochemical conversion of organic materials and is further described below.

In order to achieve the implementation ofthe above principles, the invention integrates a

30 (1) reactor nozzle that achieves a ultra-fast thorough mixing of fluidised particulate matter with a hot gas; (2) pressurised reactor chamber into which the two or more phase mix produced by the nozzle is fed;

(3) super-sonic quencher heat exchanger tubular nozzle into which the resultant vapours and gases produced in the reactor chamber are exhausted.

(4) product collection and separation system that receives the quenched vapours, gases, oils and any residual solids and separates them into various product stream for downstream storage and optional ongoing processing such as oil refining and or gas reforming.

The feedstocks can be any form of organic matter supphed in particulate form, preferably with an average diameter of less than a millimetre, such as pulverised coal, lignite, peat or biomass or any of their process derivatives, or waste products such as Refuse Derived Fuels (RDFs) from Municipal Solid Waste (MSW). The device can be used in a variety of regimes for different purposes ranging from heat and power generation, through substitute natural gas (SNG) production, to processing of organic solids into hquid fuels and chemical feedstocks for subsequent refining.

PROCESS PROBLEMS ADDRESSED BY THE INVENTION

The processing of organic particulate matter for heat and power generation, hquid fuels and chemical production is faced with a range of common problems that impedes the development of substantial fossil and biomass resources in an environmentally sound way. These are: D handling of ash components in hot gases;

D achieving extremely fast heat rates in particulate matter;

□ achieving high efficiency fast heat transfers between hot gases and other heating medium such as steam or heating fluids;

□ ultra-fast quenching of reaction products. These problems are detailed in the following sections.

Ash Problems in Hot Gases

Most fuels and feedstocks contain a certain proportion of mineral matter that

becomes ash upon combustion, or that can have detrimental effects during thermochemical conversion. This is more specifically the case with alkali salts, and in particular potassium that can vaporise at process temperature. Further, above about 700 °C, these compounds interact with other normally high melting point ash components such as silica to form eutectics with relatively low melting and vaporising points. These products create substantial deposits and corrosion problems in high efficiency boiler, reactor devices, and gas turbines.

Convertech has developed a de-ashing technology that is an inherent part of its particulate organic feedstock refining process. However, in a number of applications there is a need to remove residual volatilised alkali metal compounds from a hot gas stream produced from Convertech's refined particulate feedstocks or from other feedstocks.

In current state-of-the-art, it is common to avoid the arising of these volatile salt compounds by confining combustion temperatures to low levels where very poor efficiencies result. It is preferable to use higher combustion temperatures but particular difficulties are found in heat transfer applications when the volatile alkali metals condense as they cool. As indicated above, this results in sticky deposits in boiler tubes and in gas turbines, for instance.

To avoid boiler or gas turbine damage, it is common practice to carry out a "hot gas cleanup" where the hot gases are cooled to the level where the volatile alkali metals can condense in various kinds of "filters", "collectors" or "scrubbers". This means that the gas stream must be cooled from 900°C - 1000°C to about 600°C in order to remove the offending substances. It is usual to expect a considerable heat loss when cooling the gas by heat exchange to another medium.

The new reactor creates operating conditions that eliminate the disadvantages of low temperature combustion and/or hot gas cleaning.

Fast Heating Rates

The fundamentals of thermochemical conversion of biomass have progressed

enormously over the last two decades. The hterature points at the merits of so-called ultra-fast pyrolytic approaches over and above state-of-the-art gasification technologies.

Most ofthe latter produce unclean, that is ash loaded, gases ofthe "producer" type with low calorific values in the range of 5 to 8 MJ/m3 at STP, and considerable mass and energy losses whatever the process routes such as heat and power, or chemical synthesis. The ultra-fast pyrolytic approach offers the opportunity of unbundling the very complex reactions that are taking place in the combustion, pyrolysis and gasification stages of combustors or gasifiers, and thus of achieving better control on the production of reaction products. In ultra-fast pyrolysis heating rates of over 1000°C/second (in some cases rates of 10,000 °C/s are achieved) are applied to coarse biomass powders or very small particles in a controlled atmosphere, within well specified temperature and pressure ranges (typically between 700°C and 1000°C, and between 10 to 200 bar). Under these conditions there is no danger of exothermic runaway reaction since the processes involved are all equilibrium limited. When this set of conditions is achieved complex thermochemical conversion reactions occur very fast that breakdown the particulate feedstock in to a wide range of intermediary compounds. These compounds are unstable and very quickly degrade into lower value compounds usually encountered in "producer gas" such as hydrogen, carbon mono- and dioxide, traces of methane, water, and so on.

The aim of ultra-fast pyrolysis is to "catch" the intermediary compounds in a disequilibrium state before they have had time to degrade. One of the most advanced set of approaches in this area, for example, is ablative pyrolysis. It has been discovered that as very small biomass particles are applied to a hot surface (500- 1000°C) as a means of achieving the ultra-fast heating rates required, the solids literally melt into oil at the contact area. Because of the speed of heat transfers the oil products are projected into a fine aerosol and vaporised. By fast quenching of the oils (see below), this approach leads to substitute natural gas and petroleum oil

products (such as the so-called biocrude oils derived from biomass) of improved quality (relative to the more classical pyrolytic oils) that can be directly burnt as a fuel or subsequently upgraded into transport fuels, and fine chemicals.

So far, however, it has proved difficult to transfer ultra-fast pyrolysis from the lab to commercial scale operation. The methods used to achieve high heating rates all have substantial inherent negative sides such as high abrasion rates resulting from the impinging of particulates on hot surfaces or from the use of non-reactive solids such as jets of hot sand as heat carriers.

With its super-sonic nozzle and the use of hot gases as heat carriers, the proposed device avoids the above problems, while achieving the required high heating rates.

Fast High Efficiency Heat Exchange

The carrying out of combustion or chemical pyrolytic reaction as described above requires extremely fast heat exchanges between the reaction gases and fluids outside the reactor such as steam or thermal heating fluid. This is so in order to be able to control operation conditions, and/or extract the energy released at high efficiency levels. The rates required are 10 to 15 times higher than what is normally encountered in normal heat exchange conditions.

Fast Quenching

An allied problem is the need to quench reaction gases to a temperature low enough so that:

□ residual ash can be removed without incurring high penalties in terms of heat losses, waste products and capital costs in the case of power generation applications;

□ the intermediate hydrocarbon and carbohydrate compounds can be extracted before they have had time to degrade.

In state-of-the-art technology, quenching has been achieved by injecting cold fluids such as liquid nitrogen or spraying cold pressurised water into the gas stream. Besides the costs of implementing such approaches, they also result in the production of large volumes of liquid waste and substantial energy losses.

The Convertech approach combines the fast heat exchange effect referred to above with the quenching effect achieved by rapid pressure drop in the gas streams, without any admixion of cooling fluids in the gas stream.

BASIC PRINCIPLES

The basic principles of the invention are derived from well known technologies and scientific principles that have been applied individually in a number of very different devices ranging from rocket engines to high efficiency compact boilers. The underpinning science, however, has never been integrated in the way described below to resolve the process problems analysed earlier.

Feedstocks

The invention processes two types of feedstocks:

□ particulate organic solids with an average mesh size of less than 1 millimetre;

□ reactive or non-reactive heating gases.

In the basic Convertech refining process, biomass or low rank fossil fuels such as low rank coal, lignite or peat undergo thorough de-ashing and breakdown into their main constituents in a series of pressurised modules to produce a range of co- products. The main co-product by weight is a dry thoroughly de-ashed particulate compound whose main constituents are derived from cellulose and lignin in the case of biomass feedstocks, hence its given name of Cellolig. This particulate product can be supplied to downstream processing units at up to 33 bar and 255 °C. It has been embrittled by the hydrolysis process in the Convertech refining modules, and can therefore be easily further comminuted, by mechanical attrition resulting from the

pressure drop from 30 to say 20 bar that can be achieved through a suitable release valve or nozzle. If necessary a final milling stage can be added to bring the particulate size down to the required level.

The invention, however, can also be applied to other organic feedstocks that have not been processed by the Convertech refining technology, such as high rank coal, provided such feedstocks have been suitably pulverised and thoroughly dried and/or desiccated so as to avoid absorption of heat by entrained moisture. The heating gases carry a range of functions:

D very fast heating of the entrained particle in a high turbulence flow;

□ optional reactions with the particulate matter.

The latter include addition of hydrogen, removal of oxygen, or oxidation of the particles through such known processes as hydropyrolysis, C0 ₂ as O ₂ donor, or straight combustion with air. The feedstock gases can be hydrogen, carbon oxides, steam, air, or various mixtures thereof.

Reactor Nozzle

The required ultra-fast heating rates are achieved by co-injecting the two feedstocks into the reaction chamber through a two fluid reactor nozzle of a type similar to that used in rocket engines to achieve fast and uniform mixing ofthe fuel and oxidiser. In the prefened design, the fluidised particulate feedstock is injected as a dense mixed phase at low velocity in the central part of the nozzle, while the heating gas or gases are injected at very high velocity through an annular nozzle concentric to that used to produce the jet of particulate matter.

Very high mixing efficiencies can be achieved in this way. The injection of fluidised particulate matter at relatively low temperature (say around 200 °C) avoids risks of caking encountered with certain materials at higher temperatures with induced problems of agglomeration and devolatilisation in the injection devices. The fast heating takes place in the reactor chamber without any contact with heating

surfaces. In this way risks of abrasion of fouling of heating surfaces are avoided.

Reaction Chamber

The function ofthe reaction chamber is simply to provide the short residence time needed for the heat transfer to take place between the heating gases and the particulate matter, and from the initial pyrolytic reaction to be initiated. Depending on the desired outcome required operating conditions range between about 600 °C to 1000°C, mainly around 760°C, and between 20 bar to 150 bar.

In most apphcation excess gases are needed to carry out the heating function and favour the shifts sought in the out-of equilibrium reactions, such as excess hydrogen to favour methane synthesis. In the power generation apphcation, a suitable heating gas mix can be achieved through a partial recycle of the resulting high calorific value gases collected at the end of the super-sonic exhaust nozzles (see below) so as optimise the calorific value ofthe substitute natural gas produced.

Quencher Heat Exchange Nozzle

Heat transfer efficiency can be vastly improved by a known heat transfer phenomenon where a hot gas moving at high velocity through tubes can give up heat by convection at a rate 10 to 15 times greater than is found in conventional adiabatic heat exchange conditions. The hot gas is projected at or faster than the speed of sound through elongated essentially tubular nozzles from the pressurised reaction chamber refened to above, and which provides the impetus to get supersonic conditions.

A heat transfer fluid continuously circulated in jackets around the tubular nozzles, or through suitable adjacent passages in the tube, captures a high proportion of the energy as steam or other medium.

In some applications where the above described reaction chamber is used as a combustion chamber by additional injection of air or oxygen, the resultant pressurised combustion also provides powerful radiation heat transfer due to the

5 density ofthe gas.

By suitably designing the tubular nozzles, the high rates of heat transfer achieved can also be complemented with a substantial pressure drop between the inlet and outlet ofthe nozzles, thus achieving additional quenching of the gases within the nozzles. While this additional quenching effect is not required in power generation l o applications, it plays an important role in other apphcations where a high calorific gas for pipeline reticulation, liquid fuels, or synthesis chemicals are sought.

In these latter cases, the temperature drop will bring the gases and vapours from as high as 1000°C to about 300 °C. The speed of the gas through the nozzle is in the order of 340-480 (e.g. 475) metres per second. Given that known

15 characteristics of such nozzles allow a temperature drop of 280-300°C in a tube 2.5 metres long, the residence time in such a tube is less than 5 milliseconds. It is thus clear that the design of the nozzle can be elongated and optimised to provide the temperature drop to a level of about 300 °C within a residence time that would remain under 50 milliseconds. Total residence time from particulate feed through reaction 0 chamber to exhaust from the super-sonic nozzles would be less than one second.

Under such conditions, it is known that close to 70% conversion of carbon to methane and carbon monoxide can be achieved. The extremely good heat exchange efficiency allows for a maximum recovery of the heat expended during the pyrolysis and quenching operations.

25

APPLICATIONS

As indicated in the introduction, the system described above can be implemented in a wide variety of ways for heat and power generation, gaseous or liquid fuels and chemical synthesis feedstock production.

30

Basic Configuration

In its most basic configuration, the system would have several reactor nozzles placed at the base ofthe reaction chamber. The number of nozzles would depend on

5 the overall capacity required for the system. However, a prefened basic configuration would comprise three reactor nozzles supplying the feedstocks into the reactor chamber at an angle designed to achieve fast and uniform mixing of particulate matter and gases. The chamber would be domed. The super-sonic quencher nozzles would be placed on the dome of the chamber. l o Other configurations can be contemplated from some apphcations, for example to take advantage of radiative heat transfers from the combustion gases to the steam or other thermal fluid used as part ofthe quenching function. This can be achieved by placing the nozzles inside an enlarged reaction/combustion chamber in such a way that the gas flow doubles up along the quenching nozzles.

15

Heat and Power Generation

The high velocity heat transfer effect can be incoφorated in a gas turbine cycle which can utilise the gas cleaning system described above and where the clean gas can be routed to a gas turbine. 20 The gas turbine power can be used to drive the compressor which supplies pressurised combustion air to the reactor nozzles.

The gas pressures and temperatures would be optimised to allow a maximum suφlus of shaft torque available for connection to an alternator or other power system. In parallel, the large quantity of steam available from the quenching effect

25 could be used to drive either a back pressure or a condensing steam turbine connected to another load.

The cycle has the effect of being a combined gas turbine/steam turbine system which has a primary steam side and a secondary gas turbine side which are intimately integrated. Conventional combined cycles have the steam side as an add-on to the 30 primary gas turbine, the steam being incidentally generated from the hot exhaust gases from the gas turbine. In the new cycle, a very substantial proportion of the heat from combustion is first taken for superheated steam production.

Assuming that the gas cleanup requires a given temperature drop, the gas

available to the gas turbine will be at a relatively low temperature but could still retain considerable energy. The gas turbine can be selected from available technology or designed to exploit these particular conditions.

An additional advantage of this invention is the significantly reduced NOx emission. As combustion occurs in a pressurised chamber to provide the necessary driving force for the discharge through the super-sonic nozzles, the elevated pressure influences the combustion products by suppressing the so-called "gas water shift" reaction. This reaction is a complex series of thermally initiated radical chain reactions that can be represented as:

CO ₂ co + y ₂ o ₂

H ₂ 0 H ₂ + y ₂ o ₂

CO + H ₂ O - CO ₂ + H ₂

These reactions occur at high temperature and have three main influences on

the combustion processes:

□ the reactions are endothermic, therefore they tend to reduce the energy

liberated by the reaction;

D they increase the partial pressure of combustion products, thus increasing flue

draft, and hence exhibiting a desirable feature in terms of conventional

combustor design;

□ the radical intermediates can combine with the otherwise inert N ₂ to form the

highly undesirable NO _x compounds which are subject to regulatory emission

control in most countries.

In the Convertech device, the reduced effect on flue draft is more than largely

compensated by overall elevated pressure of combustion, while the reduced

concentration of the radical intermediates from the shift reaction reduces the

likelihood of NO _x formation and increases the flame temperature.

When the suggested system is configured to be added to a Convertech fuel

preparation system, the gas cleanup function may be deleted or substantially reduced because the fuel will have previously been "de-ashed". See our earlier patent

applications (New Zealand and PCT). In this case, the high velocity quenching

nozzles can be allowed to delivery higher temperature gas to the gas turbine which

can be made to share a larger proportion of the total load with the steam turbine section. A "split" combustion system could be provided so that part of the

combustion chamber is diverted through the high velocity tubes for steam output

whilst another part diverts its hot gas direct to the gas turbine thus giving a very wide choice of steam/power combinations for co-generation service. Many permutations

of power splits and applications will be possible for such a system.

Substitute Natural Gas, Liquid Fuels and Chemical Feedstocks

In another series of embodiments, the same general system can be employed

to fast quench the products of ultra fast pyrolysis of particulate solids such as

lignocellulosic materials derived from the processing of biomass or peat through the

Convertech refining process, coal and lignite. The latter fossil fuels can be processed

directly or preferably be upgraded by de-ashing, medium temperature hydrolytic

processing and thorough drying by means of the Convertech refining technology.

Depending upon the operation regimes different product ranges will be

obtained. At long residence time and higher temperature (for example about 1000°C,

100 bar, and 2 seconds) only gas products are produced (such as 90% methane plus carbon monoxide and traces of carbon dioxide). Under milder condition and shorter residence time the production of liquid fuels can be optimised (such as under 500 milliseconds, 800 °C and 35 to 100 bar), as well as the production of specific chemical feedstocks such as olefins or (with the equipment suitably modified) products like bucl minsterfullerene (C ₆₀ "buckyballs"), for example.

The high calorific value gas products can be finally cooled and reticulated as substitute natural gas (SNG), while the oil products can be subsequently refined using existing oil refinery technology.

Any residual char material can be recycled or processed separately.