AU2021106834A4

AU2021106834A4 - A system for the chemical recycling of end of life plastics to a plastic feedstock and fuel products using a multi-stage pyrolysis kiln

Info

Publication number: AU2021106834A4
Application number: AU2021106834A
Authority: AU
Inventors: Ian Mcintosh
Original assignee: Env Resources Pte Ltd
Current assignee: Environmental Resources Pte Ltd
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2021-11-18
Anticipated expiration: 2029-08-24
Also published as: ES1303701Y; ES1303701U

Abstract

A system for the for the recycling of organic materials, including a kiln 100, comprising first and second kiln portions 100a, 100b, each comprising an elongate reaction chamber 130a, 130b, a port 136a, 136b for receipt of organic material 500 into, a port 138a, 138b for exit of solid or liquid material out of and a port for exit of gaseous material 138a, 136b. Second kiln portion 100b is located below the first kiln portion 100a. Fluid flow passageway 135 extends between port 138a and port 136b to convey material exiting reaction chamber 130a downwardly to reaction chamber 130b and to convey gaseous material exiting reaction chamber 130b upwardly. Kiln 100 is configured for heating organic material 500 in reaction chambers 130a, 130b in an absence of oxygen thereby to decompose at least a portion thereof into hydrocarbons suitable for use as precursors for plastic manufacturing, or as hydrocarbon fuels. 0 rqi 00 "000

Description

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EDITORIAL NOTE 2021106834

There are 19 pages of description only.

Title

A system for the chemical recycling of end of life plastics to a plastic feedstock and fuel products using a multi-stage pyrolysis kiln

Technical Field

[0001] The present disclosure relates generally to the decomposition of organic compounds, such as mixed waste polymers, and more particularly to a kiln for use in such a process. The kiln, and process comprising same, been developed primarily for producing hydrocarbon products as feedstock for plastics manufacturing from waste plastics materials. However, it will be appreciated that the kiln is not limited to this use, and may, for example, also be used to decompose other organic compounds, such as those present in various forms of biomass, or produce hydrocarbon fuel products.

Background

[0002] Plastics is a material typically formed of long chain organic polymers. As a result of the relatively low cost of production and ease of manufacture, plastics materials are used in a wide variety of products around the world, including a large number of disposable products such as packaging. As consumption of disposable products formed of plastics materials increases, the associated waste plastics material also increases, leading to environmental concerns due to the long life of the plastics materials if sent to landfill. Other issues associated with the dumping of waste plastics include soil contamination and infertility.

[0003] Plastics recycling is the process ofrecovering scrap or waste plastics and reprocessing the material into useful products. However, unlike metal recycling, the recycling of plastics materials can be challenging due to low economic returns.

Recycling of plastics can face further difficulties as a result of the chemical nature of the long chain organic polymers which can make them difficult to process. Furthermore, waste plastics materials often need sorting into the various plastic resin types, e.g. polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), for separate recycling treatments.

[0004] As plastics are formed of long chain organic polymers containing hydrogen and carbon, processes have been developed for the conversion of the long chain polymer into shorter length hydrocarbon fuel products such as petrol or diesel. These processes typically involve pyrolysis of the plastics material to reduce the long-chain polymers to polymers of smaller chain length.

[0005] Current techniques for processing plastics materials into hydrocarbon products often result in the inclusion of wax and tar type products that can foul equipment and piping used in the process. In addition, the presence of particulate materials introduced to the system or formed in the course of the reaction can result in the formation of a low purity, difficult to handle sludge-like products when condensed. Furthermore, hydrocarbons condensed directly after the pyrolysis reaction are generally required to be re-heated in order to then separate out the desired hydrocarbons.

[0006] An alternative to landfill disposal of plastics is incineration. However, this has posed problems such as damage to the furnace and the emission of harmful gases and an offensive odour. Society's ever-increasing environmental consciousness has deemed incineration a largely unpopular and unsustainable method of disposing of waste plastics.

[0007] In the United States, the Package Recycle Law which prescribes the duty of recovering and reusing plastics was enacted in 1995. In view of these circumstances, various attempts have recently been made to reuse plastics waste as resources. However, two decades after the enactment of this law, only 8% of all plastics waste is actually recycled. Clearly, there are environmental drivers toward increasing the rate of recycling. However, logistical and abiding societal factors still dictate that the vast majority of plastics waste is dumped or incinerated.

[0008] A further consideration is that the mineral cost of supplying the world with its ever-increasing demand for plastics accounts for approximately 7% of the global crude oil consumption on an annual basis. In brief, it costs oil to make plastics - and unless that oil is recoverable once the plastics has served its commercial purpose, our global mineral debt only serves to increase.

[0009] In Australia there is little or no plastic recycling. Plastics are typically manufactured using naphtha or ethylene as a raw feedstock, with the majority of waste plastic streams either shipped overseas for mechanical recycling or landfilled.

[0010] The Japanese inventor Akinori Ito popularised the idea of converting waste plastics back into fuel oil through plastic pyrolysis. Pyrolysis is a thermochemical decomposition of organic material, such as plastics, at elevated temperature in the absence of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible. Pyrolysis typically occurs at temperatures in the range of 400-900 °C, at small excess pressure.

[0011] In this process, the long polymer molecules of plastics materials are broken down into shorter chains of hydrocarbons with the help of heat and pressure. A catalyst can be used to lower the temperature and increase the yield. Other substances which can be pyrolysed are biomass, waste tires, lubricating oils, coal and petroleum residues.

[0012] The basic process of pyrolysis proceeds as follows: (1) A shredding step in which the waste material must be segregated and, if possible, cleaned. Then it is shredded to speed up the reaction and to ensure that the reaction is complete. (2) An anaerobic heating step in which the shredded material is heated in a controlled manner in an oxygen-free reactor. One of the most crucial factors in this operation is

maintaining the correct temperature (-430 C for plastics) and the rate of heating, as they define the quality and the quantity of the final product. (3) A condensation step in which the gas that comes out from the reactor is condensed by passing it through a condensation tube or by directly bubbling it in water. (4) A distillation step in which the resultant mixture of oil can be used as furnace oil but is insufficiently pure for engines. In order to be able to use it as engine fuel or as raw material for plastic manufacture, the desired products need to be extracted and purified from the mixture through fractional distillation, or some other purification means.

[0013] Some of the benefits of pyrolysis are that the process does not generate harmful pollutants and that the by-products can be used as fuel for running the plant. In the case of plastics, some of the valuable products that can be extracted through waste plastic pyrolysis are naphtha, gasoline, kerosene, diesel, benzene, LPG, toluene and xylene. Moreover, the pyrolytic process is relatively efficient in that one kilogram of waste can yield up to one litre of liquid hydrocarbons.

[0014] Anhydrous pyrolysis can be used to produce ethylene and naphtha which in turn can be used as feedstock for virgin plastics manufacture, avoiding many of the lifecycle problems inherent in mechanical recycling. This is preferred option, significantly reducing the environmental costs ofplastic use. Using pyrolysis to extract fuel from end-of-life plastics is a second-best option after recycling, is environmentally preferable to landfill or waste to energy incineration , and can help reduce dependency on foreign fossil fuels and geo-extraction. Moreover, plastics-derived diesel fuel is obtainable in a form pure enough for commercial sale and consumption. Liquid fuel similar to diesel, can be made from plastic waste, with a higher cetane value and lower sulfur content than traditional diesel. On the other hand, such technologies are still in their infancy, and often struggle to attract investment due to poor economies of scale and it is a known goal of the art to find ever more efficient, and economically viable, means of obtaining hydrocarbon products from waste plastics.

[0015] European patent application 0 620 264 A2 discloses a process for making a lube oil from waste plastics. The process utilises a cracking process in a fluidised bed of inert solids and fluidised with, for instance, nitrogen. The product of the cracking is hydrotreated over an alumina catalyst or other refractory metal oxide support containing a metal component, and then optionally catalytically isomerised. The overall yield, however, is lower than desired. The isomerisation catalysts taught partially cause this result. There is no teaching ofusing better isomerisation catalysts. Also, EP 0 620 264 A2 does not teach a process of producing a high yield of heavy lube oils.

[0016] Many methods for preparing low-boiling hydrocarbons from waste plastics and high-boiling hydrocarbons are known. US 4,851,601 describes a reaction of pyrolysis in a reactor kettle (vertical or horizontal), wherein the outside wall of the kettle is heated at a high temperature while the materials therein are heated indirectly. In this method, the outside wall is apt to be deformed when the reactor is heated directly at a high temperature. The materials are readily sintered on the inside wall because of local over-heating so that the conversion yield of the reaction and the life of the reactor are greatly decreased. In addition, the coefficient of the reactor's heat transfer is relatively low, it is difficult to drain the reaction residues, and the catalytic reaction in the fixed bed needs a separate heat supply. These are the common drawbacks of the reactor kettle in the prior art.

[0017] A spiral reactor utilised in some special fields is similar to the above. Heat is indirectly transferred when it works. The outside wall of the reactor is heated directly at a high temperature, making the materials in the reactor indirectly heated. Therefore, the heat transfer coefficient is not satisfactory.

[0018] W02017/088015 discloses a system addressing some of the abovementioned drawbacks. However the design has shown to have limitations of scale due to issues with thermal expansion and heat exchange leading to a poor rate of return on investment.

[0019] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

Summary

[0020] Throughout this specification, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0021] In a first aspect, there is provided amulti-stage pyrolysis kiln for the decomposition of organic materials, such as polymers, the kiln comprising: a first kiln portion and a second kiln portion, each comprising: an elongate reaction chamber defining a longitudinal axis, the reaction chamber having a first end and an opposite second end spaced apart along the longitudinal axis; an inlet for receipt of organic material into the reaction chamber; a first outlet for exit of solid or liquid material out of the reaction chamber; and

a second outlet for exit of gaseous material out of the reaction chamber; the kiln being configured for heating organic material in the reaction chambers in an absence of oxygen thereby to decompose at least a portion of the organic material into a reaction chamber gas product stream comprising hydrocarbons suitable for use as feedstock for plastic manufacture or fuel, the second kiln portion being located below the first kiln portion; a fluid flow passageway extending between the second outlet of the first kiln portion and the inlet of the second kiln portion to convey liquid and solid material exiting the reaction chamber of the first kiln portion downwardly to the reaction chamber of the second kiln portion and to convey gaseous material exiting the reaction chamber of the second kiln portion upwardly, such that heat exchange occurs between the downwardly conveyed liquid and solid material exiting the reaction chamber of the first kiln portion and the upwardly conveyed gaseous material exiting the reaction chamber of the second kiln portion.

[0022] The kiln may be configured such that an operational temperature in the reaction chamber of the second kiln portion is higher than that of the reaction chamber of the first kiln portion, such that the downwardly conveyed liquid and solid material exiting the reaction chamber of the first kiln portion is heated by the upwardly conveyed gaseous material exiting the reaction chamber of the second kiln portion.

[0023] The inlet of the first kiln portion may be proximate the first end of the reaction chamber of the first kiln portion. The first outlet of the first kiln portion may be proximate the second end of the reaction chamber of the first kiln portion. The second outlet of the first kiln portion may be proximate the second end of the reaction chamber of the first kiln portion. The inlet of the second kiln portion may be proximate the first end of the reaction chamber of the second kiln portion. The first outlet of the second kiln portion may be proximate the second end of the reaction chamber of the second kiln portion. The second outlet of the second kiln portion may be proximate the first end of the reaction chamber of the second kiln portion. The second outlet of the first kiln portion may be located substantially directly above the second outlet of the second kiln portion.

[0024] A single port may serve as both the first outlet of the first kiln portion and the second outlet of the first kiln portion. A single port may serve as both the inlet of the second kiln portion and the second outlet of the second kiln portion.

[0025] A scrubber may be provided in fluid communication with each said reaction chamber. The scrubber may be configured to remove hydrocarbons in the reaction chamber gas product stream above a predetermined upper hydrocarbon range for returning to the reaction chamber of the first or second kiln portion for further heating in the absence of oxygen. The scrubber may comprise a single scrubber in fluid communication with all of the reaction chambers. The scrubber may be in fluid flow communication with the fluid flow passageway and extend upwardly therefrom.

[0026] The second kiln portion may be located substantially directly below the first kiln portion. Each said kiln portion may comprise an inner cylindrical tube, the interior thereof defining the reaction chamber, and an outer cylindrical tube extending concentrically around the inner tube, wherein an annular void is defined between the inner and outer tubes. The annular void of the first kiln portion may be in fluid flow communication with the annular void of the second kiln portion, for example via a fluid flow conduit extending between the annular voids. One or more vortex generators may be provided in the annular voids.

[0027] The reaction chamber of the second kiln portion may comprise a second inlet for connection to a steam source for steam sparging of the reaction chamber of the second kiln portion.

[0028] The kiln may be configured such that the temperature of the reaction chamber gas product stream does not drop substantially before entering the scrubber.

[0029] The scrubber may be configured such that a scrubber gas stream exiting the scrubber is at a temperature ofless than 350°C.

[0030] A stirrer may be provided in the reaction chamber of the first kiln portion for stirring contents thereof A stirrer may be provided in the reaction chamber of the second kiln portion for stirring contents thereof A catalyst may be provided in one or both of the reaction chambers for pushing the reaction therein towards hydrocarbons of desirable chain length and/or desired aromatic hydrocarbons.

[0031] A heater may be provided for heating the reaction chambers. The heater may comprise a heat transfer medium in the annular voids for heating the inner tubes and thereby the reaction chambers. The heat transfer medium may flow into the annular void of the second kiln portion and therefrom to the annular void of the first kiln portion.

[0032] In a second aspect, there is provided a system for the production of hydrocarbon products from organic materials, such as polymers, the system comprising: a kiln according to the first aspect; and at least one hydrocarbon recovery device for recovering hydrocarbons within a predetermined hydrocarbon range from the reaction chamber gas product stream.

[0033] The at least one hydrocarbon recovery device may comprise one or more of a fractionation column configured to condense diesel range hydrocarbons from a hydrocarbon gas stream; a condenser configured to condense petrol range hydrocarbons from a hydrocarbon gas stream; and a compression device configured to condense liquid petroleum gas (LPG) range hydrocarbons from a hydrocarbon gas stream. It will be appreciated that the selection of equipment for the hydrocarbon recovery device will depend on the hydrocarbons desired to be recovered.

[0034] The fractionation column may be in fluid communication with a gas outlet of the scrubber. The fractionation column may be further configured to divert at least a portion of condensed diesel to the scrubber for use as a scrubbing liquid.

[0035] A vacuum tower may be provided for removing water from diesel range hydrocarbons condensed by the fractionation column.

[0036] The condenser may be in fluid communication with a gas outlet of the fractionation column.

[0037] The compression device may be in fluid communication a gas outlet of the condenser.

[0038] In a third aspect, there is provided an assembly for use in the production of hydrocarbon products from organic materials, such as polymers, the assembly comprising: a kiln according to the first aspect; a heater for heating the reaction chambers; a scrubber in fluid communication with each said reaction chamber, wherein the scrubber is configured to remove hydrocarbons in the reaction chamber gas product stream above a predetermined upper hydrocarbon range and return the removed hydrocarbons to the reaction chamber of the first or second kiln portion for further heating in the absence of oxygen; and a hydrocarbon recovery device in fluid communication with the scrubber for receiving a remainder of the reaction chamber gas product stream, the hydrocarbon recovery device being configured to remove hydrocarbons within a predetermined hydrocarbon range from said remainder.

[0039] In a fourth aspect, there is provided an assembly for use in the production of hydrocarbon products from organic materials, such as waste polymers, the assembly comprising;

a kiln according to the first aspect; a heater for heating the reaction chambers; a scrubber in fluid communication with each said reaction chamber, wherein the scrubber is configured to remove hydrocarbons in the reaction chamber gas product stream above a predetermined upper hydrocarbon range and return the removed hydrocarbons to the reaction chamber of the first or second kiln portion for further heating in the absence of oxygen; a hydrocarbon recovery device in fluid communication with the scrubber for receiving a remainder of the reaction chamber gas product stream, the hydrocarbon recovery device being configured to remove hydrocarbons within a predetermined hydrocarbon range from said remainder;

a pre-shredder for prcessing bulk waste polymer feedstock;

a device for removing metal contaminants, both ferrous and non-ferrous;

a device for detecting and removing contaminating material from the waste plastic feedstock; a shredder for reducing the waste polymer feedstock to an optimal size for feeding the kiln; and a shroud enclosing the waste polymer feedstock equipment above to capture and remove dust and odours from the process and use this as combustion air for the kiln heater.

Brief Description of Drawings

[0040] One or more embodiment ofprinciples disclosed herein will now be described, by way of example only, with reference to the accompanying drawing, wherein: Figure 1 is a schematic diagram of a system for the recovery of valuable hydrocarbon products from end of life plastics, the system embodying principles disclosed herein.

Description of Embodiment(s)

[0041] Referring to Figure 1, there is provided a system 10 for the conversion of plastics to hydrocarbon products such as naphtha, diesel, petrol and liquid petroleum gas (LPG). The classification of hydrocarbon products depends primarily on the range of chain lengths of the hydrocarbons, for example diesel hydrocarbons typically range from C10 to C25, naphtha and petrol hydrocarbons from C4 to C12, and liquid petroleum gas (LPG) typically comprises a mixture of C3 and C4 hydrocarbons (can be alkenes).

[0042] The system 10 comprises a multi-stage pyrolysis kiln 100 for pyrolysis of a feed material 500. The feed material 500 may be any organic material, and, in the illustrated embodiment, is an end of life plastics material formed of long-chain organic polymers, for example end of life plastic materials such as plastic packaging. The feed material 500 may undergo pre-processing prior to introduction into the kiln 100, for example shredding or chopping to improve handling and surface area of the feed material, or sorting to minimise the amount of contaminants introduced to the system. The feed material 500 is fed to kiln 100 by a feeder 120 in a manner so as to reduce heat and gas loss from the kiln. For example, feeder 120 may comprise a double slide gate feeder or a plug screw feeder or both. The feeder 120 also allows for the control of the rate of flow of the feed material 500 into the kiln 100.

[0043] Kiln 100 comprises an upper kiln portion 100a and a lower kiln portion 100b. Lower kiln portion 100b is located substantially directly below upper kiln portion 100a. Both kiln portions 100a, 100b comprise an elongate cylindrical reaction chamber 130a, 130b, having a first end 132a, 132b and an opposite second end 134a, 134b, and through which the feed material 500 flows. Each reaction chamber 130a, 130b is oriented substantially horizontally, in use, and defines a longitudinal axis A. Each reaction chamber 130a, 130b has an inlet 136a, 136b for receipt of organic material into the reaction chamber 130a, 130b. Inlet 136a defines the point of entry into kiln 100 of feed material 500 from feeder 120. Reaction chamber 130a has an outlet 138a for exit of solid, liquid and gaseous material therefrom. Reaction chamber 130b has an outlet 138b for exit of solid and liquid material therefrom. Inlet 136b also functions as an outlet for exit of gaseous material from reaction chamber 130b. A fluid flow passageway 135 extends between outlet 138a of reaction chamber 130a and inlet/outlet 136b ofreaction chamber 130b to provide fluid flow communication therebetween. Passageway 135 conveys liquid and solid material exiting outlet 138a of reaction chamber 130a downwardly to inlet/outlet 136b of reaction chamber 130b and conveys gaseous material exiting reaction chamber 130b through inlet/outlet 136b upwardly past outlet 138a of reaction chamber 130a. It will be appreciated that heat exchange occurs between the downwardly conveyed liquid and solid material exiting reaction chamber 130a and the upwardly conveyed gaseous material exiting reaction chamber 130b.

[0044] Inlet 136a is proximate the first end 132a of reaction chamber 130a and outlet 138a is proximate the second end 134a of reaction chamber 130a. Inlet/outlet 136b is proximate the first end 132b of reaction chamber 130b, and outlet 138b is proximate the second end 134b of reaction chamber 130b. Moreover, outlet 138a of reaction chamber 130a is located substantially directly above inlet/outlet 136b of reaction chamber 130b. Inlet 136a and passageway 135 are located a longitudinally opposite ends of reaction chamber 130a. Outlet 138b and passageway 135 are located at longitudinally opposite ends of reaction chamber 130b.

[0045] Each reaction chamber 130a, 130b comprises a stirrer 140a, 140b. In the illustrated embodiment, stirrers 140a, 140b each comprise a plurality of paddles mounted transverse to the axis of a rotatable shaft that extends longitudinally through the reaction chamber 130a, 130b, for stirring the contents thereof In addition to improving heat transfer to the feed material 500, the stirrers 140a, 140b also assist in the removal of waste particulate material from the reaction chambers 130a, 130b and in prevention of waxy build-up on inner walls of the reaction chambers.

[0046] A heat source 800 is provided for heating reaction chambers 130a, 130b and their contents. Heat source 800 may comprise a heat transfer medium that flows through an annular void 160a, 160b around each reaction chamber 130a, 130b. The annular voids 160a, 160b are defined between an outer tubular wall 165a, 165b and the reaction chamber wall 139a, 139b of each kiln portion 100a, 100b. The heat transfer medium 800 transfers heat through the reaction chamber walls 139a, 139b and into the reaction chambers 130a, 130b. A conduit 167 extends between the annular regions 160a, 160b to facilitate flow of heat transfer medium therebetween. In the illustrated embodiment, the heat transfer medium 800 is directed into annular region 160b of lower kiln portion 100b and flows therefrom to annular kiln portion 160a ofupper kiln portion 100a. Accordingly, reaction chamber 130b operates at a higher temperature reaction chamber 130a. A plurality of vortex generators (not shown) are provided in annular spaces 160a, 160b to increase the heat transfer efficiency between the heat transfer medium 800 and the reaction chambers 130a, 130b by generating a vortex in the flow of heat transfer medium as it flows along the annular regions 160a, 160b.

[0047] The heat source 800 may be generated by other process equipment used in or in conjunction with the system 10. For example, the heat source 800 may comprise a heat transfer medium in the form of combustion gases from a cyclone combustor 170 used to treat waste products from the system 10, such as non-condensable gases and char, or may be any other heat source suitable for heating the reaction chambers 130a, 130b and their contents. By drawing combustion air from the shroud enclosing pre processing units, the potential for environmental impacts are reduced.

[0048] In the reaction chamber 130a of upper kiln portion 100a, the feed material 500 is heated in the absence of oxygen such that at least a portion of the feed material 500 first melts, then decomposes into a reaction chamber gas product stream 501 comprising hydrocarbons ranging from hydrogen to heavy wax, with the majority of the gases being in the liquid range. Waste particulate material, such as char, dust and ash may be formed in the reaction chamber 130a as the feed material 500 is heated or may be introduced with the feed material 500. Liquid and/or solid material, including undecomposed or partially decomposed feed material 500 and waste particulate material from reaction chamber 130a, drops from reaction chamber 130a into reaction chamber 130b via passageway 135. When it drops through passageway 135, this liquid and/or solid material from reaction chamber 130a is exposed to superheated vapour rising from reaction chamber 130b, which promotes decomposition, or further decomposition, of the liquid and/or solid material, including the cracking of heavy hydrocarbons therefrom. In reaction chamber 130b, the liquid and/or solid material from upper kiln portion 100a is heated in the absence of oxygen such that at least a further portion of the feed material 500 decomposes into a reaction chamber gas product stream 501 comprising hydrocarbons ranging from hydrogen to heavy wax, with the majority of the gases being in the liquid range. Reaction chamber 130b may be sparged with steam to promote cracking of heavy hydrocarbons from the material processed therein. Waste particulate material can be removed from reaction chamber 130b via outlet 138b.

[0049] A catalyst, such as activated bauxite, may be provided in either or both of the reaction chambers 130a, 130b for pushing the reaction therein towards hydrocarbons of a desired chain length and/or desired aromatic hydrocarbons.

[0050] The kiln 100 further comprises a gas product outlet 190 and a scrubber 200 at outlet 190. Gas product stream 501 from reaction chamber 130b rises through passageway 135 to merge with gas product stream 501 from reaction chamber 130a. The merged gas product streams 501 pass through the product outlet 190 and flow through the scrubber 200. It will be appreciated that some waste particulate material may be entrained in the gas product streams 501.

[0051] Scrubber 200 is preferably a packed scrubbing column comprising plate, structured or ring-type packing. In scrubber 200, gas product stream 501 is brought into contact with a hydrocarbon scrubbing liquid 502 for condensing heavier, higher boiling point, hydrocarbons present in gas product stream 501. The condensed heavier hydrocarbons and scrubbing liquid 502 flow back into reaction chamber 130b to undergo further reaction. The remaining, lighter weight, hydrocarbons exit scrubber 200 as a scrubber gas product stream 503. Scrubbing liquid 502 also acts to wash gas product stream 501 of entrained waste particulate material, which flows back to reaction chamber 130b with the scrubbing liquid 502 and the condensed heavier hydrocarbons.

[0052] Scrubber 200 is in direct fluid communication with the reaction chambers 130a, 130b, such that the reaction chamber gas product streams 501 flow directly from the reaction chambers 130a, 130b to scrubber 200. This minimises any cooling of gas product streams 501 prior to entering the scrubber 200, which reduces the formation and accumulation of solid waxy residue from the gas product streams 501. The above described relative positioning of reaction chambers 130a, 130b and scrubber 200 also reduces or avoids the need to reheat product from the reaction chambers 130a, 130b in order to separate out the desired hydrocarbons.

[0053] System 10 further comprises several hydrocarbon recovery devices for recovering hydrocarbons within a predetermined hydrocarbon range from gas product stream 501 produced by kiln 100. These hydrocarbon recovery devices include a fractionation column 210 configured to condense diesel range hydrocarbons, a condenser 240 configured to condense naphtha and petrol range hydrocarbons, and a gas compression and cooling device configured to condense liquid petroleum gas (LPG) range hydrocarbons.

[0054] Gas product stream 503 exiting the scrubber 200 enters fractionation column 210, in which gas product stream 503 is brought into contact with a hydrocarbon reflux 504 selected for causing diesel range hydrocarbons 506 to condense and flow out the bottom of the fractionation column 210 while gasoline and lighter hydrocarbons exit the top of fractionation column 210 as a fractionation gas product stream 505. A portion of the diesel range hydrocarbons 506 exiting the fractionation column 210 is used as the scrubbing liquid 502 for scrubbing reaction chamber gas product stream 501.

[0055] The remaining diesel 507 may then be treated prior to storage is a diesel storage vessel or returned to the kiln for further cracking. In one example, the remaining diesel 507 is treated to remove moisture, for example by vacuum drying 220, to produce treated diesel 508, which is collected and stored in a diesel storage vessel 230. In another example, the diesel 507 may undergo a solvent extraction processes, as discussed in more detail below, to extract impurities such as aromatics, sulphur compounds and similar.

[0056] It will be appreciated that the operational conditions of kin 100 and scrubber 200 will be dependent on the type of feed material 500 to be processed and the desired hydrocarbon product to be recovered. For example, targeted recovery of lighter weight liquid petroleum gas (LPG) range hydrocarbons may require higher operating temperatures in kiln 100 than for targeted recovery of diesel range hydrocarbons. Whilst the operating temperature in reaction chambers 130a, 130b is important, careful control of temperature at product outlet 190 (ie., inlet of scrubber 200) and at the outlet of scrubber 200 can play an important role in the composition of the recovered products. These temperatures can be controlled, for example, by controlling the operating temperature in reaction chambers 130a, 130b and/or controlling the flow rate of scrubbing liquid 502 into scrubber 200. Preferably, the temperature of the scrubber gas stream 503 exiting the scrubber 200 is maintained below 350°C, such that heavy, long-chain hydrocarbons, unsuitable for use, condense and flow back to the reaction chamber 130b for further treatment.

[0057] The fractionation gas product stream 505 exiting the fractionation column 210 flows through a condenser 240 configured to condense naphtha or petrol range hydrocarbons in the fractionation gas product stream 505. A portion of the condensed hydrocarbons exiting the condenser 240 are used as the hydrocarbon reflux 504 for the fractionation column 210. The remaining portion of hydrocarbons 509 is collected and stored in a storage vessel 250. As described above for diesel 507, the hydrocarbons 509 may be treated prior to storage in petrol storage vessel 250. For example, the petrol hydrocarbons 509 may undergo a solvent extraction processes, as discussed in more detail below, to extract impurities such as aromatics, sulphur compounds and similar.

[0058] Any remaining gases that were not condensed in the condenser 240, e.g., due to very low molecular weight and low boiling points, exit the condenser 240 as a condenser gas product stream 510. The condenser gas product stream 510 is fed to a gas compression and cooling device 260 configured to extract liquid petroleum gas (LPG) range hydrocarbons from the condenser gas product stream 510. The extracted LPG range hydrocarbons 511 are collected and stored in a LPG storage vessel 270.

[0059] Non-condensable gases 512 that are not recovered in the gas compression and cooling device 260 may be used in other process equipment, such as to at least partially fuel cyclone combustor 170, as described above.

[0060] It will be appreciated that the illustrated kiln 100 provides system 10 with numerous advantages. For example, using a plurality of smaller reaction chambers 130a, 130b instead of a single larger reaction chamber facilitates:

* increasing the effective length of kiln 100 without generating additional torque on stirrer 140a, 140b; • increasing the effective length of kiln 100 without increasing its footprint, as kiln portions 100a, 100b can be located above one another; • independent temperature control of each reaction chamber 130a, 130b, thereby facilitating more control over the hydrocarbon cracking profile, an increase in liquid product yield, and less hydrocarbon in ash leaving the system 10, resulting in safer and/or easier storage and/or disposal of the ash; • providing a system 10 that is more compact overall; • handling and transport of kiln 100, as the kiln portions 100a, 100b can be

separated for handling and transport, and connected together for commissioning of the system 10; • less thermal expansion due to reduced length; • need for hanger bearings reduced or avoided due to reduced shaft length; and • reduced torque requirements on stirrer shaft.

• reduced capital cost, as the smaller kiln portions 100a, 100b making up kiln 100 are cheaper to manufacture and/or install than a single larger kiln of equivalent capacity; • lower capital and operating costs than an equivalent single stage, kiln design provides an improved rate of return from 6% up to 37%, and equity multiple from 0.89 to 2.27, exceeding the industry standard of 2.00. Without this the design does not provide a viable financial model, and will not attract investment.

[0061] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Examples of such variations and/or modifications include, but are not limited to: • kiln 100 may include more than two kiln portions 100a, 100b; and/or • kiln portion 100a may have separate outlets for solid/liquid material and for gaseous material, respectively.

EDITORIAL NOTE 2021106834

There are 6 pages of claims only.

Claims

CLAIMS:

1. A multi-stage pyrolysis kiln for the decomposition of organic materials, such as waste polymers, the kiln comprising: a first kiln portion and a second kiln portion, each comprising: an elongate reaction chamber defining a longitudinal axis, the reaction chamber having a first end and an opposite second end spaced apart along the longitudinal axis; an inlet for receipt of organic material into the reaction chamber; a first outlet for exit of solid orliquid material out of the reaction chamber; and a second outlet for exit of gaseous material out of the reaction chamber; the kiln being configured for heating organic material in the reaction chambers in an absence of oxygen thereby to decompose at least a portion of the organic material into a reaction chamber gas product stream comprising hydrocarbons suitable for use in plastic manufacturing or as fuel, the second kiln portion being located below the first kiln portion; a fluid flow passageway extending between the second outlet of the first kiln portion and the inlet of the second kiln portion to convey liquid and solid material exiting the reaction chamber of the first kiln portion downwardly to the reaction chamber of the second kiln portion and to convey gaseous material exiting the reaction chamber of the second kiln portion upwardly, such that heat exchange occurs between the downwardly conveyed liquid and solid material exiting the reaction chamber of the first kiln portion and the upwardly conveyed gaseous material exiting the reaction chamber of the second kiln portion.

2. The kiln of claim 1, being configured such that an operational temperature in the reaction chamber of the second kiln portion is higher than that of the reaction chamber of the first kiln portion, such that, in use, the downwardly conveyed liquid and solid material exiting the reaction chamber of the first kiln portion is heated by the upwardly conveyed gaseous material exiting the reaction chamber of the second kiln portion.

3. The kiln of claim 1 or claim 2, wherein: the inlet of the first kiln portion is proximate the first end of the reaction chamber of the first kiln portion; and/or the first outlet of the first kiln portion is proximate the second end of the reaction chamber of the first kiln portion; and/or the second outlet of the first kiln portion is proximate the second end of the reaction chamber of the first kiln portion; and/or the inlet of the second kiln portion is proximate the first end of the reaction chamber of the second kiln portion; and/or the first outlet of the second kiln portion is proximate the second end of the reaction chamber of the second kiln portion; and/or the second outlet of the second kiln portion is proximate the first end of the reaction chamber of the second kiln portion.

4. The kiln of any one of the preceding claims, wherein the inlet of the second kiln portion and the second outlet of the second kiln portion are both located at the same end of the second kiln portion.

5. The kiln of any one of the preceding claims, wherein a single port serves as both the inlet of the second kiln portion and the second outlet of the second kiln portion.

6. The kiln of any one of the preceding claims, wherein the first outlet of the first kiln portion is located substantially directly above the second outlet of the second kiln portion.

7. The kiln of any one of the preceding claims, wherein a single port serves as both the first outlet of the first kiln portion and the second outlet of the first kiln portion.

8. The kiln of any one of the preceding claims, comprising a scrubber in fluid communication with each said reaction chamber.

9. The kiln of claim 8, wherein the scrubber is configured to remove hydrocarbons in the reaction chamber gas product stream above a predetermined upper hydrocarbon range for returning to the reaction chamber of the first or second kiln portion for further heating in the absence of oxygen.

10. The kiln of claim 8 or claim 9, wherein the scrubber comprises a single scrubber in fluid communication with all of the reaction chambers.

11. The kiln of any one of claims 8 to 10, wherein the scrubber is in fluid flow communication with the fluid flow passageway and extends upwardly therefrom.

12. The kiln of any one of the preceding claims, wherein the second kiln portion is located substantially directly below the first kiln portion.

13. The kiln of any one of the preceding claims, wherein the first and second reaction chambers are heated by a heat transfer medium, the heat transfer medium heating the second reaction chamber before heating the first reaction chamber.

14. The kiln of any one of the preceding claims, wherein each said kiln portion comprises an inner cylindrical tube, the interior thereof defining the reaction chamber, and an outer cylindrical tube extending around the inner tube, wherein an annular void is defined between the inner and outer tubes, the annular void of the first kiln portion being in fluid flow communication with the annular void of the second kiln portion.

15. The kiln of any one of the preceding claims, wherein the reaction chamber of the second kiln portion comprises a second inlet for connection to a steam source for steam sparging of the reaction chamber of the second kiln portion.

16. A system for the production of hydrocarbon products from organic materials, such as polymers, the system comprising: a kiln according to any one of the preceding claims; and at least one hydrocarbon recovery device for recovering hydrocarbons within a predetermined hydrocarbon range from the reaction chamber gas product stream.

17. The system of claim 16, wherein the at least one hydrocarbon recovery device comprises one or more of a fractionation column configured to condense diesel range hydrocarbons from a hydrocarbon gas stream; a condenser configured to condense naphtha and or petrol range hydrocarbons from a hydrocarbon gas stream; and a compression device configured to condense liquid petroleum gas (LPG) range hydrocarbons from a hydrocarbon gas stream.

18. The system of claim 17 when dependent on any one of claims 8 to 11 or any one of claims 12 to 15 when dependent on any one of claims 8 to 11, comprising the fractionation column, the fractionation column being in fluid communication with a gas outlet of the scrubber.

19. The system of claim 18, wherein the fractionation column is configured to divert at least a portion of condensed diesel to the scrubber for use as a scrubbing liquid in the scrubber.

20. The system of claim 18 or claim 19, comprising the condenser, the condenser being in fluid communication with a gas outlet of the fractionation column.

21. The system of claim 20, comprising the compression device, the compression device being in fluid communication a gas outlet of the condenser.

22. An assembly for use in the production of hydrocarbon products from organic materials, such as polymers, the assembly comprising: a kiln according to any one of claim 1 to 15; a heater for heating the reaction chambers; a scrubber in fluid communication with each said reaction chamber, wherein the scrubber is configured to remove hydrocarbons in the reaction chamber gas product stream above a predetermined upper hydrocarbon range and return the removed hydrocarbons to the reaction chamber of the first or second kiln portion for further heating in the absence of oxygen; and a hydrocarbon recovery device in fluid communication with the scrubber for receiving a remainder of the reaction chamber gas product stream, the hydrocarbon recovery device being configured to remove hydrocarbons within a predetermined hydrocarbon range from said remainder.

23. The assembly of claim 22, wherein the scrubber comprises a single scrubber in fluid communication with all of the reaction chambers.

24. The kiln of claim 22 or claim 23, wherein the scrubber is in fluid flow communication with the fluid flow passageway and extends upwardly therefrom.

25. An assembly for the production of hydrocarbon products from organic materials such as end oflife polymers, the assembly comprising:

a kiln according to any one of claim 22 to 24;

a system to process bulk end of life plastic feedstock comprising;

a pre-shredder to reduce bulk polymers for sorting;

a metal detection and removal system including a top belt magnet to remove ferrous metals, and an eddy-current separator for non-ferrous metals;

a near infrared sorter to segregate unwanted materials from the polymer feedstock;

a final shredder to reduce the waste polymer feedstock to a suitable size for feeding the kiln and a shroud and extraction system to contain dust and odours generated during shredding and sorting that provides combustion air for the heating of the kiln reaction chambers.