Upgrading residues, heavy oils and plastics

Example 1: Oil Residue Upgrading

Summary

[0275]A technology was developed to upgrade low-value feed stocks to high-value products. One such feed stock is the lube oil residue (LOR) gathered from the bottoms fraction of a vacuum distillation plant for recycling used lube oil. This residue is made up of the non-distillable fraction of the oil and contains contaminating components retained in the oil through use and additive residues.

[0276]Lube oil residue was successfully processed. About 70% of the resulting upgraded LOR could be distilled to a strongly upgraded oil product after treatment. By contrast only about 20% of the as received LOR could be distilled under comparable conditions.

[0277]The results confirm that supercritical water upgrading of LOR using the disclosed methods provides substantial benefits:

(i) A large fraction of the LOR is cracked to lighter products, leading to hydrocarbon oils boiling in the diesel and heavy gas oil ranges;

(ii) The residue remaining after upgrading followed by distillation is reduced to approximately one quarter of its original volume, with potential for further reduction by further processing.

[0278]These outcomes provide the possibility of deriving revenue-generating products from the upgraded hydrocarbon oils while substantially reducing disposal costs for residual materials.

Introduction

[0279]Lube oil is a commonly used product designed to perform several functions including the lubrication of moving machinery parts as well as cooling, cleaning and corrosion control. However, after a certain amount of usage, lube oil becomes unfit for further use due to the accumulation of contaminants and chemical changes in the oil. The main contaminants include:

(i) Combustion Products

[0280] Water. [0281] Soot and carbon. [0282] Fuel.

(ii) Abrasives

[0283] Road dust. [0284] Wear metals.

(iii) Chemical Products [0285] Oxidation products. [0286] Depleted additive remnants.

[0287]It is possible to recycle the lube oil and such re-refined lubricants have been produced. So as to recycle the oil, it is necessary to remove the afore-mentioned contaminants and restore the oil to its original condition. This is achieved first through dehydration and then diesel stripping. The diesel stripping is a vacuum distillation process that extracts the different fractions including light fuel or diesel; lubricating oil; and lube oil residue, or LOR.

[0288]The LOR makes up the non-distillable part of the feed stock and is the only fraction of the three that is, for the most part, considered useless for commercial applications though it has been used successfully as bitumen extender in roads. It contains all of the carbon, wear metals, and degraded additives as well as most of the lead and oxidation products.

[0289]The objective of these trials was to ascertain indicative yields of saleable products from LOR using the methods described herein.

[0290]Approximately 100 kg of LOR on a dry basis was received from an Australian supplier. The feed stock for the plant was prepared by mixing the LOR with demineralised water to make a mixture that was pumpable in the reactor plant. Such preparation will not be necessary in a dedicated upgrading unit, however some initial dilution with water was required in this case to reduce feed viscosity because the pilot plant used lacks heated feed systems. Additionally, water is the upgrading medium in the hydrothermal process used and therefore some water must be added. The mixture was stabilised by heating it to 65° C. and processing it through a colloid mill so as to both reduce the droplet size of the LOR suspended in the water and ensure that the mixture was homogeneous. During the trial runs, the slurry was maintained as homogenous in the feed tank through the use of a stirrer.

Process Outline

[0291]A simplified process flow diagram for the process used is shown in FIG. 1.

Trial 1

[0292]The reactor temperature for this trial run ranged between 395° C. and 405° C. at 260 Bar. The estimated residence time of the LOR in the reactor was 25 minutes and a mass balance for the run is shown below in Table 3.

[0293]Trail 1 produced samples of upgraded LOR which had been processed by the technology. Analysis of these samples is presented in further below.

TABLE 3 LOR trial 1 simplified mass balance Production Yields % dry basis (db) Oil (as emulsion) 87.5 NCG Gas 7.0 Difference 5.5 Notes to Table: Db: dry basis No obvious solid residues were detected in samples of the oil (as an oil in water emulsion). Small amount of solids may have quickly settled out of the emulsion in the product tank. The difference term includes such solids, any water made in the reactor and also any mass unaccounted for.

[0294]The mass balance closed to within 5.5%, a good outcome for a relatively short pilot plant run. The upgraded oil product was recovered as a stable oil-in-water emulsion, from which the oil was subsequently recovered in the laboratory. The emulsion formed as a result of the surfactants present in the LOR and also due to a relatively small orifice size used for depressurization in this test run, the overall effect being similar to a homogenizer. The mass unaccounted for in the run was the equivalent of approximately 0.4 kg and may have included LOR coating the pipe walls of the feed system and collection tank as well as slight inaccuracies in the mass totalisers into the plant.

[0295]The acronym SCULOR (Super-Critically Upgraded Lube Oil Residue) to distinguish the upgraded material from the feed LOR.

Trial 2

[0296]A second trial run on the SPP was completed on the 24 Mar. 2015. Based on the results of the first run, some improvements to the processing method were made:

(i) The LOR/water mixture was heated to reaction temperature directly instead of partially by injecting supercritical steam. This increased the concentration of LOR in the reactor.

(ii) Capillaries rather than nozzles were used for pressure letdown to reduce emulsion formation.

(iii) A shorter reactor was used to reduce residence time, a desirable outcome as it reduces reactor cost.

[0297]The reactor temperature for this trial run ranged between 415° C. and 425° C. at 260 Bar, so slightly hotter than the previous run. Direct heating the feed rather than using supercritical water addition boosted the oil concentration in the reactors from 10% to 28%. The estimated residence time of the LOR in the reactor was 6 minutes. The pH of the water in the product tank was lowered by addition of acid to de-stabilize emulsion droplets, and the SCULOR was recovered as an oil phase floating on a water phase after cooling. A mass balance after product acidification for the run is shown below in Table 4.

TABLE 4 LOR trial simplified mass balance Trial 2 after acidification Production Yields % dry basis (db) Oil 78.5 NCG Gas 11.8 Water Phase Ether extractables 0.28 Residues 2.4 Difference 5.2 Notes to Table. The water phase was tested by solvent extraction to confirm the virtual absence of oil product extractable into ether. The water phase residue includes non-ether soluble organics and inorganic salts from the feed LOR. Difference term includes any water made in the reactor and also any mass unaccounted for.

The mass balance was again well closed, to within 5.2%.

Oil Analysis

[0298]The upgraded LOR, SCULOR, was distilled under reduced pressure in an ASTM D1160 type apparatus. The distilled material was dramatically improved in appearance and viscosity compared to the LOR, as illustrated in FIG. 2. The upgrading process substantially changed the composition of the LOR, as illustrated by FIG. 3. Substantial cracking has increased the distillable material from about 20% of the LOR to about 70% of the SCULOR. The most prominent change was the large increase in lighter oil fractions and reduction in the heavy residue. The higher temperatures in Trial 2 produced slightly more of mid-boiling fractions than Trial 1, however the low boiling fractions below 110° C. were reduced, presumably having been cracked to volatile vapours, consistent with a higher NCG gas yield in Trial 2. Roughly 40% of the distilled material boils approximately in the diesel range, note that the boiling ranges at a reduced pressure of 10 torr (13 mbar). The lower boiling fractions contain some polar material, discussed further below.

[0299]FIG. 4 shows approximate boiling point curves of the SCULOR products from Trials 1 and 2, constructed by joining the means of the upper and lower boiling ranges of the fractions.

[0300]Results of elemental analysis of some distillate fractions from Trial 1 are shown in Table 5. The three lowest boiling fractions contained some polar material (lower layer) that was denser than the oil fraction (upper layer). Separation of the upper and lower layers may not have been complete, it is probable that some contamination of the hydrocarbon layer with the polar layer occurred, and vice versa, and this should be borne in mind when examining the analysis data. The polar material presumably originates from additives and contaminants in the lube oils (e.g. glycols, sulphonates) and may include some water. The higher boiling fractions are predominantly hydrocarbon in nature with a molar hydrogen to carbon ratio close to two, indicating that they are likely mainly paraffins. Heteroatom contents are quite low.

TABLE 5 Elemental composition of the various fractions obtained by vacuum distillation of the Cat-HTR lube oil residue (SCULOR) - Trial 1 Boiling range at 10 Density Elemental Composition (%) Fraction torr (° C.) (g/ml) C H N S O 1 top 56.0-72.2 0.815 82.18 14.62 <0.05 0.49 2.68 1 bottom 56.0-72.3 1.086 41.10 10.39 0.34 <0.05 48.13 2 top 72.3-107.7 0.817 — — — — — 2 bottom 72.3-107.8 1.087 — — — — — 3 top 107.7-160.0 0.912 77.68 13.80 0.17 0.13 8.23 3 bottom 107.7-160.1 1.035 52.70 10.16 0.90 0.18 36.07 4 160.1-212.7 0.865 81.53 14.45 0.30 0.51 3.23 5 212.7-248.5 0.873 83.48 14.80 0.22 0.40 1.11 6 248.5-281.0 0.875 83.42 14.87 0.20 0.32 1.20 7 281.0-303.5 0.89 83.90 14.84 0.15 0.25 0.87 8 303.5-331.8 0.888 85.22 14.18 0.08 0.26 0.28 9 331.8-354.3 0.883 86.04 13.76 0.17 0.08 0.00 Residue 354.3+ Note to Table: Oxygen obtained by difference

Gas Analysis

[0301]Table 6 shows the non-condensable gases produced from the upgrading run. The gas yields and compositions suggest the presence of significant cracking of the larger carbon-chain molecules of the LOR. The higher abundance of C1-C3 hydrocarbons in Trial 2 is consistent with more cracking activity at a higher reaction temperature. The concentration and absolute abundance of hydrogen sulphide in Trial 1 is probably too low for the measurement to be reliable.

TABLE 6 NCG Composition from LOR Cat-HTR Trials Trial 1 LOR Trial 2 LOR feed 40% wt. Feed 28% wt. with SCW injection Electrical heating Gas Volume % Volume % Methane 5.51 11.37 Carbon Monoxide <0.015 0.26 Hydrogen 31.89 22.95 Ethylene 2.81 6.10 Ethane 3.20 5.94 Propylene 3.67 8.48 Propane 3.16 8.23 Carbon Dioxide 49.70 35.27 Hydrogen Sulphide <0.015 1.40 NCG Yield, weight % 7.0 11.8

CONCLUSIONS

[0302]The trials described in this report confirm that supercritical water upgrading of LOR using the disclosed methods provides substantial benefits:

(i) A large fraction of the LOR is cracked to lighter products, leading to hydrocarbon oils boiling in the diesel and heavy gas oil ranges

(ii) The residue remaining after upgrading followed by distillation is reduced to approximately one quarter of its original volume, with potential for further reduction by further processing

[0303]These outcomes provide the possibility of deriving revenue-generating products from the upgraded hydrocarbon oils while substantially reducing disposal costs for residual materials.

Abbreviations

[0304] Db: Dry Basis [0305] IER: Ignite Energy Resources Pty Ltd [0306] LOR: Lube Oil Residue [0307] NCG: Non-Condensable Gas [0308] SCO: Synthetic Crude Oil [0309] SCULOR: Super-Critically Upgraded Lube Oil Residue [0310] SPP: Small Pilot Plant

Example 2: Oil Residue Upgrading in Combination with Polymers

Introduction

[0311]Example 2 is a prophetic Example.

[0312]Plastic and/or rubber and/or other polymeric material (polymers) may be used in combination with heavy oil components of the feedstock mixture for cracking in the reactor. Accordingly, plastic and/or rubber and/or other polymeric material (polymers) may be added to the feedstock mixture for cracking in the reactor according to the methods described below.

[0313]The polymers may be characterised in part by their glass transition temperatures Tg and/or their melting temperatures Tm in the case of semi-crystalline or crystalline polymers. Above Tg polymers generally exhibit rubbery characteristics. Non-limiting examples of glass transition temperatures and melting temperatures are given below in Table 7.

TABLE 7 Tg and Tm temperatures of exemplary polymers Polymer Tm ° C. Tg ° C. Polyethylene (PE) 135 −68 Polypropylene (PP) 176 −8 Polystyrene (PS) 240 100 Poly(methyl methacrylate) PMMA 200 105 Poly(vinyl chloride) PVC 180 82 Poly(vinylidene fluoride) (PVDF) 210 −39 Polyisoprene 28 −70 Nylon-6,6 265 50 Source: Williams (1971) cited in, “Introduction to Polymer Science and Chemistry: A Problem-Solving Approach” Second Edition, Manas Chanda, CRC Press, 11 Jan. 2013.

[0314]Non limiting examples of polymers, plastics and rubbers that can be treated according to the methods of Examples 2-X include Polyethylene (PE), Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polypropylene (PP), Polyester, Poly(ethylene terephthalate) (PET), poly(lactic acid) PLA, Poly (vinyl chloride) (PVC), Polystyrene (PS), Polyamide, Nylon, Nylon 6, Nylon 6,6, Acrylonitrile-Butadiene-Styrene (ABS), Poly(Ethylene vinyl alcohol) (E/VAL), Poly(Melamine formaldehyde) (MF), Poly(Phenol-formaldehyde) (PF), Epoxies, Polyacetal, (Acetal), Polyacrylates (Acrylic), Polyacrylonitrile (PAN), Polyamide-imide (PAI), Polyaryletherketone (PAEK), Polybutadiene (PBD), Polybutylene (PB), Polycarbonate (PC), Polydicyclopentadiene (PDCP), Polyketone (PK), polycondensate, Polyetheretherketone (PEEK), Polyetherimide (PEI), Polyethersulfone (PES), Polyethylenechlorinates, (PEC), Polyimide, (PI), Polymethylpentene (PMP), Poly(phenylene Oxide) (PPO), Polyphenylene Sulfide (PPS), Polyphthalamide, (PTA), Polysulfone (PSU), Polyurethane, (PU), Poly(vinylidene chloride) (PVDC), Poly(tetrafluoroethylene) PTFE, Poly(fluoroxy alkane) PFA, Poly(siloxanes), silicones, thermosplastics, thermosetting polymers, natural rubbers, tyre rubbers, ethylene propylene diene monomer rubbers EPDM, chloroprene rubbers, acrylonitrile butadiene (nitrile) rubbers, polyacrylate rubbers, Ethylene Acrylic rubbers, Styrene-butadiene rubbers, Polyester urethane rubbers, Polyether urethane rubbers, Fluorosilicone rubbers, silicone rubbers, and copolymers and mixtures thereof.

[0315]Polymers treated according to the methods of Examples 2.1-2.10 may be in the form of mixed or sorted waste plastics and in some cases may be contaminated with organic and inorganic impurities. The waste plastic material may require some pre-processing before being processed according to the methods of the present invention. For example, the waste plastic may require sieving or screening to remove abrasive particles.

[0316]Without limiting the mode of action polymers treated according to the methods of Examples 2-4 may be cracked to liquids having lower boiling and melting points or they may directly or indirectly act as sources of hydrogen which is then incorporated into the product liquids.

LOR=lube oil residue

PE=polyethylene LDPE=Low density polyethylene

Polymer=a polymeric, plastic, elastomeric or rubber material or mixture of such materials.

Example 2.1

[0317]PE is ground to a powder and suspended in LOR at a temperature of 70° C. or greater such that the viscosity of the continuous phase is sufficiently low to form a pumpable suspension. At elevated temperatures the PE may begin to dissolve into the oil. For example polyethylene solubility in mineral oil increased from about 20 g/100 g at 50° C. to about 100 g/100 g at 65° C. according to Litkovets et al. [Chemistry and Technology of Fuels and Oils, December 1988, Volume 24, Issue 12, pp 556-559, Solubility of polyethylene in a mineral oil, E. A. Litkovets, I. M. Bolyuk, A. M. Zeliznyi]. The melting temperature of LDPE is approximately 110° C. The mixture is pressurized using a high-pressure pump and is subsequently contacted with supercritical steam and raised to the reaction temperature. The contact with the supercritical steam provides water as an aqueous solvent and reactant for the cracking reactions. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0318]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The initial mixture is between about 1% PE by weight and about 40% PE by weight and between about 99% and about 60% LOR by weight. The reaction pressure is between about 40 bar and about 300 bar and preferably between about 180 bar and 250 bar.

[0319]Optionally, as illustrated in FIG. 1, the reaction mixture is pre-heated in a heater before contact with the supercritical steam. Optionally the heater is in the form of a heat exchanger which uses heat recovered from the cooler also illustrated in FIG. 1, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock. In this example the temperature of the mixture leaving the pre-heater is in the range 150° C.-300° C.

Example 2.2

[0320]Polymer is ground to a powder and suspended in heavy oil at a temperature sufficient to enable formation of pumpable suspension, for example between about 30° C. and about 200° C. The polymer and heavy oil may be mixed in any proportion. The mixture is pressurized using a high-pressure pump and is subsequently contacted with supercritical steam and raised to the reaction temperature. The contact with the supercritical steams provides water as an aqueous solvent and reactant for the cracking reactions. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0321]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The reaction pressure is between about 40 bar and about 300 bar.

[0322]Optionally, as illustrated in FIG. 1, the reaction mixture is pre-heated in a heater before contact with the supercritical steam. Optionally the heater is in the form of a heat exchanger which uses heat recovered from the cooler also illustrated in FIG. 1, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock.

Example 2.3

[0323]PE is added to LOR in a stirred heating tank at a temperature of 50-90° C. The mixture is stirred until the PE dissolves into the oil. For example polyethylene solubility in mineral oil increased from about 20 g/100 g at 50° C. to about 100 g/100 g at 65° C. according to Litkovets et al. [Chemistry and Technology of Fuels and Oils, December 1988, Volume 24, Issue 12, pp 556-559, Solubility of polyethylene in a mineral oil, E. A. Litkovets, I. M. Bolyuk, A. M. Zeliznyi]. The mixture is pressurized using a high-pressure pump and is subsequently contacted with supercritical steam and raised to the reaction temperature. The contact with the supercritical steam provides water as an aqueous solvent and reactant for the cracking reactions. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0324]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The initial mixture is between about 1% PE by weight and about 40% PE by weight and between about 99% and about 60% LOR by weight. The reaction pressure is between about 40 bar and about 300 bar and preferably between about 180 bar and 250 bar.

[0325]Optionally, as illustrated in FIG. 1, the reaction mixture is pre-heated in a heater before contact with the supercritical steam. Optionally the heater is in the form of a heat exchanger which uses heat recovered from the cooler also illustrated in FIG. 1, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock. In this example the temperature of the mixture leaving the pre-heater is in the range 150-300° C.

Example 2.4

[0326]Polymer is added to heavy oil in a stirred heating tank at a temperature of about 50-200° C. The mixture is stirred until the polymer dissolves into the oil. For example polyethylene solubility in mineral oil increased from about 20 g/100 g at 50° C. to about 100 g/100 g at 65° C. according to Litkovets et al. [Chemistry and Technology of Fuels and Oils, December 1988, Volume 24, Issue 12, pp 556-559, Solubility of polyethylene in a mineral oil, E. A. Litkovets, I. M. Bolyuk, A. M. Zeliznyi]. The mixture is pressurized using a high-pressure pump and is subsequently contacted with supercritical steam and raised to the reaction temperature. The contact with the supercritical steam provides water as an aqueous solvent and reactant for the cracking reactions. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0327]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The reaction pressure is between about 40 bar and about 300 bar. The polymer and heavy oil may be mixed initially in any proportion that provides for a pumpable liquid once heated and stirred. It will be recognized by those skilled in the art that suitable mixtures will depend upon the phase behaviour and mutual solubilities of the polymer and heavy oil phases. For example the initial mixture may comprise 99% by weight polymer and 1% by weight heavy oil or 1% polymer and 99% heavy oil.

[0328]Optionally, as illustrated in FIG. 1, the reaction mixture is pre-heated in a heater before contact with the supercritical steam. Optionally the heater is in the form of a heat exchanger which uses heat recovered from the cooler also illustrated in FIG. 1, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock.

Example 2.5

[0329]PE is ground to a powder and added to LOR and water. The mixture is stirred or passed through an emulsifier to form an intimately mixed emulsion of the components. The emulsion is optionally stored in a stirred holding tank as a buffer and then pressurized using a high-pressure pump. At elevated temperatures the PE may begin to dissolve into the oil. For example polyethylene solubility in mineral oil increased from about 20 g/100 g at 50° C. to about 100 g/100 g at 65° C. according to Litkovets et al. [Chemistry and Technology of Fuels and Oils, December 1988, Volume 24, Issue 12, pp 556-559, Solubility of polyethylene in a mineral oil, E. A. Litkovets, I. M. Bolyuk, A. M. Zeliznyi]. The melting temperature of LDPE is about 110° C. The mixture is pressurized using a high-pressure pump and is subsequently raised to the reaction temperature by means of a heater or series of heaters. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0330]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The initial mixture is between about 1% PE by weight and about 40% PE by weight and between about 90% and about 60% LOR by weight and between about 5% and about 30% water by weight. The reaction pressure is between about 40 bar and about 300 bar and preferably between about 180 bar and 250 bar.

[0331]Optionally one or more of the heaters is in the form of a heat exchanger which uses heat recovered from the cooling and/or depressurization of the reaction products, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock.

Example 2.6

[0332]Polymer is ground to a powder and added to heavy oil and water. The mixture is stirred or passed through an emulsifier to form an intimately mixed emulsion of the components. The emulsion is optionally stored in a stirred holding tank as a buffer and then pressurized using a high-pressure pump. The mixture is pressurized using a high-pressure pump and is subsequently raised to the reaction temperature by means of a heater or series of heaters. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0333]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The initial mixture is between about 5% water by weight and about 30 water by weight. The polymer and heavy oil may be present in any proportion that gives rise to a pumpable slurry upon mixing. For example the mixture may consist of 10% by weight water, 1% by weight polymer and 89% by weight heavy oil, or 10% by weight water and 89% by weight polymer and 1% by weight heavy oil. The reaction pressure is between about 40 bar and about 300 bar.

[0334]Optionally one or more of the heaters is in the form of a heat exchanger which uses heat recovered from the cooling and/or depressurization of the reaction products, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock.

Example 2.7

[0335]The method is carried out according to any of Examples 2.1-2.6 with the addition of lignocellulosic biomass to the reaction mixture. For example ground wheat straw is added such that it comprises 10% by weight of the reaction mixture. In another example, pine sawdust is added such that it comprises 10% by weight of the reaction mixture.

Example 2.8

[0336]The method is carried out according to any of Examples 2.1-2.7 with the addition of lignite (brown coal) to the reaction mixture as a solid substrate. For example lignite added such that it comprises 10% by weight of the reaction mixture.

Example 2.9

[0337]The method is carried out according to any of Examples 2.1-2.8 with the addition of a catalyst after the reaction mixture has been raised to the reaction temperature. For example, sodium hydroxide is added as a base catalyst to the extent of 0.1-10 weight percent of the non-aqueous reactant weight by means of injection of an aqueous sodium hydroxide solution using a high pressure dosing pump.

Example 2.10

[0338]The method is carried out according to any of Examples 2.1-2.9 with the additional feature that a part of the product oil is recycled into the process before the reactor, serving in part to reduce the viscosity of the reaction mixture.

[0339]Example 3 is a prophetic Example.

[0340]Plastic and/or rubber and/or other polymeric material (polymers) may be used as a feedstock for cracking in the reactor in the absence of heavy oil components. Accordingly, plastic and/or rubber and/or other polymeric material (polymers) may be used as a feedstock for cracking in the reactor according to the methods described below.

[0341]The polymers may be characterised in part by their glass transition temperatures Tg and/or their melting temperatures Tm in the case of semi-crystalline or crystalline polymers. Above Tg polymers generally exhibit rubbery characteristics. Non-limiting examples of glass transition temperatures and melting temperatures are given above in Table 7.

[0342]Non limiting examples of polymers, plastics and rubbers that can be treated according to the methods of Examples 3-X include Polyethylene (PE), Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polypropylene (PP), Polyester, Poly(ethylene terephthalate) (PET), poly(lactic acid) PLA, Poly (vinyl chloride) (PVC), Polystyrene (PS), Polyamide, Nylon, Nylon 6, Nylon 6,6, Acrylonitrile-Butadiene-Styrene (ABS), Poly(Ethylene vinyl alcohol) (E/VAL), Poly(Melamine formaldehyde) (MF), Poly(Phenol-formaldehyde) (PF), Epoxies, Polyacetal, (Acetal), Polyacrylates (Acrylic), Polyacrylonitrile (PAN), Polyamide-imide (PAI), Polyaryletherketone (PAEK), Polybutadiene (PBD), Polybutylene (PB), Polycarbonate (PC), Polydicyclopentadiene (PDCP), Polyketone (PK), polycondensate, Polyetheretherketone (PEEK), Polyetherimide (PEI), Polyethersulfone (PES), Polyethylenechlorinates, (PEC), Polyimide, (PI), Polymethylpentene (PMP), Poly(phenylene Oxide) (PPO), Polyphenylene Sulfide (PPS), Polyphthalamide, (PTA), Polysulfone (PSU), Polyurethane, (PU), Poly(vinylidene chloride) (PVDC), Poly(tetrafluoroethylene) PTFE, Poly(fluoroxy alkane) PFA, Poly(siloxanes), silicones, thermosplastics, thermosetting polymers, natural rubbers, tyre rubbers, ethylene propylene diene monomer rubbers EPDM, chloroprene rubbers, acrylonitrile butadiene (nitrile) rubbers, polyacrylate rubbers, Ethylene Acrylic rubbers, Styrene-butadiene rubbers, Polyester urethane rubbers, Polyether urethane rubbers, Fluorosilicone rubbers, silicone rubbers, and copolymers and mixtures thereof.

[0343]Polymers treated according to the methods of Examples 3.1-3.2 may be in the form of mixed or sorted waste plastics and in some cases may be contaminated with organic and inorganic impurities. The waste plastic material may require some pre-processing before being processed according to the methods of the present invention. For example, the waste plastic may require sieving or screening to remove abrasive particles.

[0344]Without limitation to a mode of action, one advantage of the methods described herein over existing methods of recycling plastics waste is that thermosetting plastics, and polymers containing fillers and extenders can be converted to hydrocarbon liquids by means of the invention. Thermosetting plastics or polymers in general cannot be melted into a liquid state to make them suitable for feeding to continuous cracking or recycling processes. Polymers, plastics or rubbers containing fillers and extenders, for example, carbon black, silica, gypsum, calcium carbonate (limestone), kaolin (clay) and alumina, cannot effectively be reprocessed by pyrolysis or catalytic or thermal cracking because of the problems associated with the inorganic fillers. In the present invention the inorganic fillers are separated from the oil products during the hydrothermal reaction and subsequent phase separation and are recovered as a dense solid phase or as an aqueous suspension (see Examples 3.1-3.2).

[0345]Without limiting the mode of action another advantage of the methods described herein is that mixtures of plastics, for example plastic wastes or End of Life (EOL) plastic wastes containing chlorine-containing plastics such as poly(vinyl chloride) (PVC) can be processed without producing environmentally damaging concentrations of chlorinated dioxins and furans, sometimes known as dioxin-like compounds (DLCs). Production of DLCs is a substantial problem for combustion and pyrolysis of plastics or polymer mixes containing PVC. In the methods described herein, organically-bonded chlorine contained in polymers with carbon-chlorine such as PVC may react to become inorganic chlorine dissolved in the aqueous phase, in the form of, for example, hydrochloric acid and/or sodium chloride and/or potassium chloride and/or calcium chloride. The methods described herein provide analogous advantages in the treatment of polymers or plastics containing bromine.

[0346]In some embodiments the methods described herein may be used to treat mixed plastics and polymers as opposed to largely pure individual feeds of polymers such as PE or PP. Without limiting the mode of action, some plastics (e.g. polystyrene (PS)) crack at lower temperatures, for example at about 420° C., than others (e.g. polyethene (PE)) which may crack at 450-480° C. Free radicals formed in the cracking of more reactive polymers such as PS may react with less reactive polymers such as PE, thereby causing them to crack effectively at lower reaction temperatures.

[0347]PE=polyethylene LDPE=Low density polyethylene

[0348]Polymer=a polymeric, plastic, elastomeric or rubber material or mixture of such materials.

Example 3.1

[0349]Thermosetting Polymer is ground to a powder and added to heavy oil and water. The mixture is stirred or passed through an emulsifier to form an intimately mixed emulsion of the components. The emulsion is optionally stored in a stirred holding tank as a buffer and then pressurized using a high-pressure pump. The mixture is pressurized using a high-pressure pump and is subsequently raised to the reaction temperature by means of a heater or series of heaters. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0350]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The initial mixture is between about 5% water by weight and about 30% water by weight. The polymer and heavy oil may be present in any proportion that gives rise to a pumpable slurry upon mixing. For example the mixture may consist of approximately: 10% by weight water, 1% by weight polymer and 89% by weight heavy oil, or 10% by weight water and 89% by weight polymer and 1% by weight heavy oil. The reaction pressure is between about 40 bar and about 300 bar.

[0351]Optionally one or more of the heaters is in the form of a heat exchanger which uses heat recovered from the cooling and/or depressurization of the reaction products, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock.

Example 3.2

[0352]Polymer containing filler is ground to a powder and added to heavy oil and water. The mixture is stirred or passed through an emulsifier to form an intimately mixed emulsion of the components. The emulsion is optionally stored in a stirred holding tank as a buffer and then pressurized using a high-pressure pump. The mixture is pressurized using a high-pressure pump and is subsequently raised to the reaction temperature by means of a heater or series of heaters. The mixture is continuously pumped through a reaction vessel to give a residence time for cracking reactions to occur. At the end of the residence time the mixture is optionally cooled and then depressurized to a pressure close to atmospheric pressure in one or more depressurization steps. After depressurization the mixture of reaction products is separated into four main phases being a gas or vapour phase, an oil phase, a water phase and a solid phase. The filler originally present in the polymer is distributed between the solid phase and the aqueous phase. The oil phase contains the desired cracked oil products that can be separated from the water and solid phases by physical means widely known in the art for example centrifugation, decantation, filtration, and distillation.

[0353]The residence time is between about 1 minute and about 30 minutes (e.g. between about 1 minute and about 10 minutes). The reaction temperature is between about 380° C. and 480° C. (e.g. approximately 450° C., or approximately 400° C.). The initial mixture is between about 5% water by weight and about 30 water by weight. The polymer and heavy oil may be present in any proportion that gives rise to a pumpable slurry upon mixing. For example the mixture may consist of approximately: 10% by weight water, 1% by weight polymer and 89% by weight heavy oil, or 10% by weight water and 89% by weight polymer and 1% by weight heavy oil. The reaction pressure is between about 40 bar and about 300 bar.

[0354]Optionally one or more of the heaters is in the form of a heat exchanger which uses heat recovered from the cooling and/or depressurization of the reaction products, so as to reduce the amount of external heat input required to accomplish the processing of the feedstock.