AU2017213547A1 - Process and plant for conversion of waste plastic material into fuel products - Google Patents

Abstract

A process, comprising heating waste plastic material to form molten waste plastic material; feeding the molten waste plastic material to a pyrolysis reactor; heating the molten waste plastic material in the pyrolysis reactor to a temperature of 3900C to 410 0C to form pyrolysis gases; feeding the pyrolysis gases to one or more condensers to cool the gases into fractions for recovery as fuel products. pU-

Description

PROCESS AND PLANT FOR CONVERSION OF WASTE PLASTIC MATERIAL INTO FUEL PRODUCTS

FIELD [0001] The present invention relates to a process and plant for conversion of waste plastic material into fuel products.

BACKGROUND [0002] The present applicant's Australian patent AU 2005221728, which is incorporated by reference in its entirety, describes a process and plant for conversion of waste plastic material into fuel products.

[0003] The present invention is directed to an improvement or modification of the invention described in AU 2005221728. Specifically, the present applicant has found that the process and plant can be modified slightly and still yield satisfactory results.

SUMMARY [0004] According to the present invention, there is a provided process, comprising: heating waste plastic material to form molten waste plastic material;

feeding the molten waste plastic material to a pyrolysis reactor;

heating the molten waste plastic material in the pyrolysis reactor to a temperature of 390°C to 410°C to form pyrolysis gases;

feeding the pyrolysis gases to one or more condensers to cool the gases into fractions for recovery as fuel products.

[0005] The waste plastic material may be heated to a temperature of 280°C to 320°C to form the molten plastic material.

[0006] The fuel products may comprise at least a majority by weight diesel fuel products.

2017213547 11 Aug 2017 [0007] The fuel products may comprise fuel products with carbon chains of a length between C6 and C25, peaking at C16.

[0008] The fuel products may be substantially equivalent to diesel fuels specified in Australian Standard AS 3570-1998.

[0009] The present invention also provides a plant, comprising:

a heated extruder configured to heat waste plastic material to form molten waste plastic material;

a pyrolysis reactor configured to receive and heat the molten waste plastic material to a temperature of 390°C to 410°C to form pyrolysis gases;

one or more condensers configured to receive and cool the pyrolysis gases into fractions for recovery as fuel products.

[0010] The heated extruder may be configured to heat the waste plastic material to a temperature of 280°C to 320°C to form the molten plastic material.

[0011] The fuel products may comprise at least a majority by weight diesel fuel products.

[0012] The fuel products may comprise fuel products with carbon chains of a length between C6 and C25, peaking at C16.

[0013] The fuel products may be substantially equivalent to diesel fuels specified in Australian Standard AS 3570-1998.

[0014] The present invention also provides a fuel product made by the process described above, or the plant described above.

-2 2017213547 11 Aug 2017

BRIEF DESCRIPTION OF DRAWINGS [0015] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 illustrates a diagrammatic overview of a thermolysis system with major features according to a first preferred embodiment of the present invention;

Figure 2 illustrates a plan view of a plant layout of a thermolysis system according to the first preferred embodiment of the present invention;

Figure 3 illustrates an elevation or side view of the plant layout shown in Figure 2;

Figure 4 illustrates a gas chromatography chromatogram chart indicating the relative proportion of carbon chain lengths within normal diesel fuel. The Y axis of this chart indicates the quantity;

Figure 5 illustrates a gas chromatography chromatogram chart indicating the relative proportion of carbon chain lengths within diesel fuel produced by the thermolysis system of the first preferred embodiment of the present invention. The Y axis of this chart indicates the quantity;

Figure 6 illustrates a diagrammatic overview of a thermolysis system with major features according to a second preferred embodiment of the present invention; and

Figure 7 illustrates a diagrammatic overview of a desulphurising system.

DETAILED DESCRIPTION [0016] Unless defined otherwise in this specification, all technical terms are used herein according to their conventional definitions as they are commonly used and understood by those of ordinary skill in the art.

[0017] Referring to the figures wherein like reference numerals designate like or corresponding parts throughout the several views, and referring particularly to Figures 1, 2 and 3, an overview process 6 and plant set up for converting waste plastic to diesel fuel using a batch process according to the invention is shown.

-32017213547 11 Aug 2017

Process operation [0018] Mixed waste plastics in their original form of plastic sheets, drums, rolls, blocks, and flat pieces are placed in a stockpile 11 and moved via an underfloor variable speed pan conveyor 13, through to a granulator 12 to reduce the size of the large items of waste plastic. An over-band magnet 15 and metals container 14 is situated above the conveyor 13 to remove any metals prior to entry into the granulator 12. From the granulator 12, the reduced plastics are delivered (for example, by conveyor, auger or blower) through to a fluidised holding silo 17. Although a variety of mechanisms could be used to transfer the plastic from one place to another, delivery in this preferred method is achieved via a blower 16. A dust collector 18 associated with the holding silo 17 collects excess dust, created by the action of the blower 16. All operations just described are preliminary preparations and may or may not be completed outside the normal operating times of the general thermolysis system discussed below.

THERMOLYSIS PROCESS [0019] To begin the thermolysis process, granulated waste plastics are drawn from the holding silo 17 via a second blower 19 and force feeder 20, into a hot-melt feed system 21 including a heat extruder, which melts the waste plastics to a temperature of 280°C to 320°C to form molten plastic material for adequate liquefied flow into a heated melt distribution manifold 22 via heated pipes which maintain adequate flow rates. The distribution manifold 22 is a valve operated system allowing distribution of molten waste through four separate outlet pipes which each lead to a separate pyrolysis reactor 26a, 26b, 26c or 26d. Although the description is made with reference to four reactors, it is to be understood that the present invention is applicable to any number of reactors, designated at feature 26 herein. The reactor receiving molten waste is preferably filled to 80% capacity with molten waste and then sealed and atmospheric ambient gases are substantially purged through the introduction of a preferably nitrogen gas blanket. Nitrogen is sourced from the nitrogen generator 25, through a nitrogen storage vessel 24, according to a nitrogen monitoring device 23. The gas used to purge the

-4 2017213547 11 Aug 2017 atmospheric gas may otherwise be selected from the group consisting of helium, or other inert gases or combinations thereof.

[0020] Each pyrolysis reactor is situated inside a heating unit, such as a furnace 28 with a natural gas burner 27. Furnace heat is applied to bring the internal temperature of the main pyrolysis reactor up to a temperature of 390°C to 410°C. While it is not intended to be bound to any particular theory, it is believed that this pyrolysis temperature alone is a variable which is optimal to produce distillable and condensable gaseous/vapor pyrolysis products with much larger light hydrocarbon and diesel fractions that are suitable for producing predominantly diesel fuel products. Optionally, standard internal rotating agitators 42 ensure even heat transfer and a homogenous plastic mixture. Non feedstock materials or contaminants then fall to the bottom of the reactor 26 to create a carbonaceous char material which must be regularly removed before it builds-up on the pyrolysis reactor walls, wherein it acts as a thermal insulator and lowers the heat transfer to the plastic waste material. Char is therefore removed by suitable means, such as being continually scrapped off by rotating blades so that liberated char accumulates as a friable fine black powder at the bottom of the pyrolysis reactor, wherein it is vacuumed out by hand after each batch. However, as will be explained below with reference to an alternative continuous process, an auger positioned at the base of the reactor can be used to periodically remove accumulated char.

[0021] To effect faster input and output of waste material, active cooling is achieved by cooling the inside of each reactor with N₂ from the N₂ line, and external cooling of the reactor by the burner fan blowing air around the reactor inside the furnace, which is used on each of the main reactors 26 to reduce the cooling time from the standard (prior art) 12 hours to a maximum (for the plant and process of the invention) of 7 hours, allowing faster turnaround between one process cycle and the next. Cooling may be implemented by fan or by other suitable cooling means known in the art.

[0022] With a system of at least four pyrolysis reactors available for operation, one or two reactors may be set to operate and optionally deliver pyrolysis gases to one or more condensers 30, 30a, or optionally to the catalytic converter 29. While one or two

-52017213547 11 Aug 2017 reactors deliver these gases as required, the remaining reactors may be prepared for a subsequent batch of molten plastic input from the hot melt system, thus allowing a semicontinuous operation and fuel output as a result of staggering the operation of the reactors. The valved heat distribution manifold 22 may be used to direct molten plastic material into any of the reactors as necessary to allow for system operation in a semicontinuous manner.

[0023] The next reactor in sequence of operation is pre-heated to between 170°C220°C while the liquefied feedstock fills the reactor to 80% capacity. Upon completion of filling, the selected main reactor temperature is raised to a temperature of 390°C to 410°C and the molten waste plastic in the sealed reactor is made gaseous by pyrolysis at this temperature causing at least partial breaking of carbon chain lengths randomly into various lengths.

[0024] The pyrolysis gases are then drawn through into one or more condensers 30, 30a, or optionally into a catalytic converter reaction tower 29 where the gas components are thermolytically cracked. Optionally, the catalytic reaction tower 29 contains a system of plates made from a special catalytic metal alloy. The metal plates are positioned so that the hot pyrolysis gases must take a torturous path to maximize contact area and time with the metal plates. The catalyst reactor 29 is heated to 220°C or greater using the exhaust gases from the furnace of the selected pyrolysis reactor 26. The metal catalyst cracks carbon parafinic chains longer than C25 and reforms chains shorter than C6. There is conversion of alpha-olefin chains (1-alkenes) to saturated alkanes. The catalyst ensures that the final fuel has a carbon chain distribution in the range C8-C25 and peaking at C16 (cetane). The metal catalyzers are made of metals including Ni and Cu, or ceramics or zeolites, in shape of punched plate and wire mesh type. The other catalysts include MCM-41 and the silicates of iron Fe3+, cobalt Co2+, nickel Ni2+, Raney nickel, manganese Mn2+, chromium Cr3+, copper Cu2+, and/or their mixtures. The catalytic plates may be made from any one of these metals, or a combination thereof. The catalyst is preferably not consumed or poisoned. The catalytic tower 29 uses technology known in the petrochemical industry and all detail concerning the processes of the reaction tower are publicly available in JP 3344952.

-62017213547 11 Aug 2017 [0025] Thermolytically cracked gases are then drawn from the reaction tower 29 into one or more condensers 30 and/or 30a, where gases are distilled into separate fractions. Condenser 30 cools and distils the gases, drawing off liquids condensed by contact with a 60°C inlet temperature condensing coil. Condenser 30a cools and distils gases using two 20°C inlet temperature coils and a top condensing coil having an inlet temperature of 8°C for light fractions. There are three cooling coils in the second condenser 30a and these are cooled with cooling tower water or water chiller units 31. Water flows through preferably three coils run co-current with the direction of pyrolysis gas flow. At each coil position there is a catchment tray and a bubble cap so the hot pyrolysis vapours must flow through the condensing coils. This allows efficient condensation of the pyrolysis condensates. Cooling tower or chiller water also flows to some of the seals throughout the line to keep them cool. In particular, seals that are most advantageously cooled include the agitator seal on the agitator shaft 42 and the seal on the reactor 26 inspection port (man hole) in the reactor lid.

[0026] The remaining non-condensable gases (NCG) not condensed by the 8°C condensing coil are piped through to a gas scrubber 34 which supplies mildly basic water to scrub out the acid, neutralize the remaining NCGs, and render the gases suitable for incineration by the off-gas burner 40. Alternatively, the gas may be recycled to a burner in the furnace as necessary. A caustic water tank 36 supplies alkaline water which is regularly dosed with caustic from a caustic make up tank 35 via a dosing pump to maintaining the correct pH value in the caustic water tank 36.

[0027] From the condensers, the bulk of fractionated fuel that is not the light component is piped into an oil recovery tank 33, or other operating tanks designed for the storage of liquid fuels, in this embodiment intermediate tanks 32. The fractionated fuels is then piped to a centrifuge 38, noting that more than one centrifuge may be necessary depending on the production volumes. The centrifuge removes carbon particles, water, ammonium hydroxide, and other contaminates that may be present in the fuel. The fuel is then pumped to quality assurance (QA) tanks 39, from which it is sent to mass storage tank 41.

-72017213547 11 Aug 2017

Carbon chain length distribution [0028] The resultant liquid fuel is not a 'pure' compound but a mixture of straight-chain and branched alkanes, cyclic saturated hydrocarbons, and aromatics consistent with a premium diesel fuel composition. The finished cleaned fuels are piped to a storage tank 41, for later distribution, by various means consistent with diesel fuel handling requirements.

[0029] With particular reference to Figures 4 and 5, thermolysis diesel made by the batch process as described above and regular (conventional) diesel fuel have been analyzed by gas chromatography (GC). The resultant chromatograms give a ‘fingerprint’ of the diesel with respect to the proportion of hydrocarbon chains of various carbon chain lengths. To perform as diesel fuel, the inventors have found that the fuel must be substantially rich in chains with a carbon chain length peaking around C16 (ie, cetane). With reference to Figs 4 and 5, the carbon chain length distribution curve for regular diesel and thermolysis diesel produced in accordance with the present invention respectively are shown. It is important to note that a higher proportion of light fraction (especially C8, C9, C11, and C13) is demonstrably present in the thermolysis produced fuel shown in Figure 5 compared to regular diesel shown in Figure 4.

Flash point modification [0030] To meet the relevant standards for transportation diesel fuel (e.g. AS3570-1998), it is necessary to increase the flash point of the thermolysis diesel to above 45°C- 53°C, preferably up to at least 61.5°C or a relevant minimum specification of standard. This can be achieved by removing a proportion of the light fraction in the fuel (approx. 5-7% by weight). It is accordingly necessary to strip the light fractions from the thermolysis diesel. This is achievable by removing the light fraction with boiling points less than 160°C, which accounts for about 5-7% of the thermolysis fuel (see table below).

[0031] The light fractions condensed in the top 8°C condensing coil of the second condenser 30a are treated separately from the heavier fractions. The light liquid stream is piped to a lights tank 37 where it is stored. The lights are separated from the heavier

-82017213547 11 Aug 2017 fractions to ensure that the heavier fractions (diesel fuel) remain at specified flash points, not less than 61.5°C.

[0032] Table 1 discloses the full distillation range data [in accordance with American Society for Testing and Materials standard ASTM D86] for diesel made according to batch process described above (and regular diesel fuel in parenthesis):

Table 1

Initial boiling point	141.5°C	(190°C)
5% recovery	154.5°C	(210°C)
10% recovery	172.5°C	(240°C)
20% recovery	209.5°C	(250°C)
30% recovery	245.5°C	(265°C)
40% recovery	270.5°C	(270°C)
50% recovery	282.5°C	(285°C)
60% recovery	290.5°C	(295°C)
70% recovery	297.5°C	(310°C)
80% recovery	307.5°C	(330°C)
90% recovery	321.5°C	(345°C)
95% recovery	332.5°C	(360°C)
Final boiling point	348.5°C	(380°C)
Recovery	98% (98.5%)
Loss	1% (0.5%)
Barometric reading	102.5 kPa

[0033] In order to shift the boiling point range to a higher temperature and concomitantly increase the flash point of the fuel, any one or more of a number of inline strategies can be employed as part of the thermolysis process of the invention:

(i) Operate the condenser coils (not shown) at a higher operating temperature thus preventing condensation of the lighter fractions and allowing these them to carry on in the gas stream to the acid scrubber 34 and subsequently to the off gas burner 40.

(ii) Heating the fuel in the primary oil recovery tank 33 by running heating fluid through the heat exchanger coils. In this way the light fraction can be taken off

2017213547 11 Aug 2017 while the process is running. The heating coils use hot water to prevent waxing in the bottom of the tanks but hot thermal fluid (heat transfer oil) may be used to keep the tanks around 80-100°C. Under these conditions the light vapours gently flash off. Because the venting of flammable hydrocarbons to the atmosphere is not permitted in many countries, it is preferable and mandatory in some countries to send these light gases to the off gas burner 40 or to otherwise capture them for disposal, recycling, or use as light fuel.

(iii) Although it is not permitted to process flammable liquids in centrifuges for health and safety reasons in many countries, it is technically possible to do so provided suitable health and safety practices are followed.

[0034] Each of the above techniques for removing the unwanted light fraction can be used individually or in any combination thereof.

Thermolysis process mass balance [0035] As an example of the use of the present invention, the following details are provided by way of example only and the invention is not to be construed as being limited by the following:

[0036] MASS BALANCE FOR THERMOLYSIS PLANT - PER 1000kg of processed clean feed stock made by the batch process according to one aspect of the invention

1. MATERIAL INPUT • 10,000kg of post industrial waste, composed of 55% polyethylene (PE), 28% polypropylene (PP), and 17% polystyrene (PS) * • Natural gas for furnace burner = 75 Gj or 2100 m³ • Nitrogen gas = 1.7 m³ x 4 = 6.8 m³

2. OUTPUTS • 10-15% Non condensable gases ί by weight kg φφ • 3-5% (Wt) char residue • Waste fraction from centrifuge = 10 kg (carbon, tar, and water)

2017213547 11 Aug 2017 • Remaining, approximately 8,250 kg liquid fuel I 0.81 SG produces yield of 10,185 litres • Removal of 6% of light fractions in process produces on “spec” diesel fuel of nett. 9,574 litres.

• Ammoniated water from centrifuge = 88 L x 0.9 (density) = 79.5 kg • Scrubber waste stream = < 3.3 kg (neutralized by NaOH) [0037] Notes:

• The above mass balance is for clean PE/PP PS feedstock. If the feedstock is post-consumer PE containing contaminates, the solid residue portion of the feedstock would be expected to be at least 5% by weight of feedstock. Also the waste portion from centrifuge would also be expected to increase as the contaminates are expected to contain water which would be processed within the reactor.

ί Off-gas composition is mainly saturated short-chain hydrocarbons including methane, ethylene, ethane, propylene, propane, n-butane, and iso-butane.

φφ Flue gas composition from off-gas incinerator is:

NOx:	198 ppm
SOx:	< 5 ppm
Temp.:	438°C
H20 content:	13%
dust density:	0.06 g/m

SEMI-CONTINUOUS THERMOLYSIS PROCESS [0038] A second embodiment of the invention will now be described with reference to Figure 6. The thermolysis reactor and down stream train are purged by an inert gas, like nitrogen, through pipe line 109. Nitrogen can be supplied from a nitrogen generator or from gas bottles. The nitrogen is managed by a monitoring device in the main control cabinet PLC and computer system and discrete controllers.

-11 2017213547 11 Aug 2017 [0039] Plastic flake (<15mm²) is delivered by any means into the fluidized silo 101. The plastic flake is then taken by a conveyor or auger 102 or blown, to the crammer 103. The plastic is then compressed by the crammer and delivered into a pre-heated extruder barrel 104 (heated steel barrel with screw). The barrel 104 is jacketed 132 and heated via heating medium which is transfixed from the heating medium vessel 130. The heating medium vessel 130 contains a medium, like oil, that is delivered to the heating jacket 132 of the barrel via the heating medium piping 131. The heating medium vessel 130 is heated from the hot flue gases being exhausted from the furnace 110 via exhaust flue 115. The plastic is melted inside the barrel between 280-320°C. The melted plastic is forced along by the rotation of the screw inside the barrel directing the melted plastic through the hot melt line 105. The line is pre-heated by electric or other means in case of cold starting through a two way valve 106 (this valve will not exist in a single reactor system) which directs the hot melted plastic into the pyrolysis reactors or single reactor 107. The pyrolysis reactor is situated within the pyrolysis reactor furnace 110. The pyrolysis reactor, usually manufactured from stainless steel, is pre-heated to 200-270°C by the burner 111. Optionally, when the melted plastic begins to flow into the reactor, the agitator 108 is activated. The agitator 108 rotates inside the pyrolysis reactor 107, the blades of the agitator 108 having a close tolerance clearance between the walls 107a of the reactor 107 and the edge of the blades 108a. The blades 108a substantially span the inside diameter of the reactor and extend up the walls 107a of the reactor 107 slightly protruding beyond the liquid level of the melted plastic in the reactor 107. The operation of the agitator 108 assists to evenly distribute the heat throughout the molten plastic.

[0040] When an initial charge of approximately 1000kg-2000kg or approximately 50% capacity of melted plastic is received in the reactor 107, the furnace 110 temperature is caused to rise to 500-650°C, thereby transferring additional heat inside the pyrolysis reactor 107, raising it to between 390-410°C. At this temperature, the plastic becomes gaseous. The reaction of the plastic at this temperature causes the plastic carbon chain lengths to randomly break into various lengths. A subsequent reaction occurs in the catalytic converter 118, the short carbon chain lengths reform and further breaking of

-12 2017213547 11 Aug 2017 longer chains lengths occur, such that the distribution is in the range of C8 to C25 and peaking at C16 (cetane).

[0041] The pressure inside the reactor 107 rises marginally above atmospheric to 1.08 bar. The pyrolysis gas is subsequently forced to exit the reactor 107 through the path of least resistance being the pyrolysis gas pipe 128 into one or more condensers 119, or optionally the catalyst tower 118. The catalyst is not consumed or poisoned. The catalyst tower 118 contains a series of plates 118a selected from the group including ceramics, zeolites, the silicates of iron Fe3+, cobalt Co2+, nickel Ni2+, Raney nickel, manganese Mn2+, chromium Cr3+, copper Cu2+, Rhenium Nickel, and/or their mixtures or the catalyst MCM-41. MCM-41 (Mobile Crystalline Material) is a silicate obtained by a templating mechanism. It is ordered to some degree, so that there are arrays of non intersecting hexagonal channels, identifiable by TEM, XRD, and vapor absorption. By changing the length of the template molecule, the width of the channels can be controlled to be within 2 to 10 nm. The walls of the channels are amorphous SiO₂. This feature, together with its exceptional porosity (up to 80%), makes MCM-41 the least mechanically stable compared to, e.g., other porous silicas, silica gels, or zeolites. Attempts to synthesize crystalline MCM-41 are underway.

[0042] The catalyst tower 118 is housed in a jacket 117, (usually manufactured from stainless steel), through which exhaust gases from the furnace 110 are diverted through a pipe 116 to heat the catalyst plates 118a to 220°C or greater. The metal plates 118a are positioned so that the hot pyrolysis gases must take a torturous path to maximise contact area and time with the metal plates 118a. The hot pyrolysis gases react with the catalytic plates 118a. The metal catalyst of the plates 118a cracks carbon parafinic chains longer than C25 and reforms chains shorter than C6. There is conversion of alpha-olefin chains (1-alkenes) to saturated alkanes. The catalyst of the plates 118a ensures that the final fuel has a carbon chain distribution in the range C8-C25 and peaking at C16 (cetane).

[0043] The reformed pyrolysis gases proceed from the catalytic converter 118 to the distillation tower 119, where the gases are condensed in their various fractions. The

-132017213547 11 Aug 2017 distillation tower 119 operates in its known form. The various fractions of liquid exit the distillation tower 11 via process lines 120 and enter oil recovery tanks 121. The fuel oil liquid is further pumped to one or more operating intermediate tanks 19. The intermediate tanks 129 can store one day’s production. A centrifuge 125, specified for diesel oil operation, is located downstream of the intermediate tanks 129. The centrifuge 125 processes the oil and removes any or virtually all solids and water contained in the oil. However, as will be described below, desulphurisation, a desirable process to remove sulphur contamination of the fuel, requires a chemical process rather than the aforedescribed physical treatment. The centrifuge 125 delivers this oil to a Quality Assurance tank 126 where any additives can be added as necessary, and samples taken for testing. The fuel oil can be sent to mass storage or distributed as necessary.

[0044] Other products exiting the distillation tower(s) or condenser(s), are non condensable gases and lights, commonly referred to as white spirits, being the lightest fraction of the carbon chains, typical having chain lengths of less than C6. This product is delivered to the lights tank 124 via process piping 120 where it is stored for distribution.

[0045] The non condensable gases continue in the process train and are directed to the gas scrubber 122 where the gases are scrubbed with water. The gas scrubber 122 water is periodically, as necessary, automatically dosed with a caustic agent to neutralise the acids which are added during the scrubbing process. Gases that are not condensed during the scrubbing process are recycled into the furnace 110 to be used for heating.

[0046] Char residue remains suspended in the molten plastic during the pyrolysis process. The semi-continuous system is designed to hold approximately 400-600kg of char per reactor. When this limit is reached, it is indicated by a level indicator 114 which signals to the hot melt feeder to stop feeding melted plastic into the reactor 107. The pyrolysis process continues to operate until all of the existing plastic is pyrolysed and the reactor 107 is empty of plastic. The control system turns on the auger system 112

-14 2017213547 11 Aug 2017 which is built into the pyrolysis reactor 107. The auger 112 extracts the char from the reactor 107 and empties it into a char vessel 113 for removal afterwards. The agitator 108 continues to operate to ensure that all of the char is evacuated from the reactor

107. When this is complete, the semi-continuous process commences again from the beginning.

[0047] It is noted that the operation of the condenser 119 is substantially the same as for the condenser 30 included in the batch system as described with reference to Figures 1 to 3.

Thermolysis mass balance [0048] The values of yield are dependent on plastic types as different plastics have inherent molecular structures that effect yield rates.

[0049] For example, 1000 kg of mixed plastic (printed film, waste packaging, etc.) yields the following output:

• 50kg of char • 125 of off gas • 825kg of liquid fuel I specific gravity 0.82 = 1006 litres of liquid fuel o 60 litres of lights o 946 litres of diesel oil fuel

Energy • 250 kW/hr of power • 30 Gj of natural gas for heating.

DIESEL DESULPHURISATION PROCESS

Summary [0050] Referring to Figure 7, a desulphurisation process removes inorganic sulphur by water wash and cyclone separation, and organic sulphur by oxidation and absorption.

-152017213547 11 Aug 2017

Detail [0051] Diesel from the Storage Tank (200) is mixed with water, and pumped into a Hydrocyclone Separator (201). The pump is a high-shear type in order to provide a high degree of mixing of water and diesel. Inorganic compounds in the diesel are present in micro-droplets of water, and thus pass into the bulk water phase. The Hydrocyclone removes substantially all of the water, and hence the inorganic sulphur.

[0052] Removal of organic sulphur compounds is achieved by oxidising them to polar compounds, which are then susceptible to absorption onto zeolite beads. Two optional gaseous oxidising agents are proposed - ozone and oxygen. In the ozone option, the gas is supplied by a conventional Ozone Generator and mixed into the diesel stream. In the oxygen option, oxygen is mixed into the diesel stream, after which free oxygen radicals are generated in the stream by means of ultrasonic sound waves. In both options, sufficient length of pipe is provided downstream (202) to allow the oxidisation reactions to proceed to completion.

[0053] The stream then passes through a silica gel Guard Bed (203) which serves to prolong the life of the more expensive zeolite beds. Two zeolite absorption vessels are provided (204 A/B), each consisting of a bed of zeolite beads. Diesel passes through one vessel whilst the other vessel is being regenerated using ethanol. Polar organic sulphur compounds are adsorbed onto the zeolite beads, and hence removed from the diesel stream, which goes to storage. Lean ethanol from tank 207 is pumped through the regenerating bed, desorbing the polar sulphur compounds from the bed before collection in the Rich Ethanol Tank (205). Sulphur-rich compounds are removed from the ethanol stream by distillation in an Ethanol Still (206). A sulphur-rich hydrocarbon stream is produced from the bottom of the stream, and may be re-used in the process as fuel.

Equipment legend for FIGURE 7:

200. Diesel storage tank

201. Hydrocyclone separator

202. Ultrasonic reactor

2017213547 11 Aug 2017

203. Reaction pipe

204. Silica gel guard bed

205. A/B Zeolite absorption vessel

206. Rich ethanol tank

207. Ethanol Still

208. Lean ethanol tank [0054] For the purpose of this specification, the word “comprising” means “including but not limited to”, and the word comprises has a corresponding meaning.

[0055] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.

[0056] Item list for 10TPD batch plant described with reference to Figures 1 to 3.

11. Plastic stock pile

12. Conveyor

13. Granulator

14. Metals container

15. Magnet

16. Blower

17. Fluidised Silo

18. Dust collector

19. Blower

20. Force feeder

21. Hot melt feed

22. Hot melt manifold

23. Nitrogen monitoring device

24. Nitrogen storage vessel

25. Nitrogen generator a,b,c,d. Pyrolysis reactor

27. Burner

2017213547 11 Aug 2017

28. Furnace

29. Catalytic converter, (catalytic reactor)

a. Condenser

31. Chiller unit (water tower)

32. Intermediate tank (operating tanks)

33. Oil recovery tank

34. Gas scrubber

35. Caustic make up tank

36. Caustic water tank

37. Lights tank

38. Centrifuge

39. Quality assurance (QA) tank

40. Off gas burner

41. Storage tank

42. Agitator [0057] Item list for Figure 6.

101. Fluidised hopper

102. Flake delivery system

103. Crammer

104. Hot melt extruder

105. Hot melt line

106. Two way valve

107. Pyrolysis reactor

107a. Reactor wall

108. Agitator

108a. Agitator blades

109. nitrogen line

110. Furnace

111. Gas burner

112. Char removal auger

113. vessel for containing char

2017213547 11 Aug 2017

114. Height, detector

115. Furnace exhaust flue

116. Exhaust flue to catalytic tower

117. Heating jacket

118. Catalytic tower

118a. Catalyst plates

119. Distillation column

120. Process piping

121. Oil recovery tanks

122. Gas scrubber

123. Non condensable gas line to furnace

124. Lights tank

125. Centrifuge

126. QA tank

127. Mass storage

128. Pyrolysis gas pipe

129. Intermediate tank

130. Heating medium vessel

131. Heating medium piping

132. Heating jacket

Claims (11)

1. A process, comprising:

heating waste plastic material to form molten waste plastic material;

feeding the molten waste plastic material to a pyrolysis reactor;

heating the molten waste plastic material in the pyrolysis reactor to a temperature of 390°C to 410°C to form pyrolysis gases;

feeding the pyrolysis gases to one or more condensers to cool the gases into fractions for recovery as fuel products.

2. The process of claim 1, wherein the waste plastic material is heated to a temperature of 280°C to 320°C to form the molten plastic material.

3. The process of claim 1 or 2, wherein the fuel products comprise at least a majority by weight diesel fuel products.

4. The process of any preceding claim, wherein the fuel products comprise fuel products with carbon chains of a length between C6 and C25, peaking at C16.

5. The process of any proceeding claim, wherein the fuel products are substantially equivalent to diesel fuels specified in Australian Standard AS 3570-1998.

6. A plant, comprising:

a heated extruder configured to heat waste plastic material to form molten waste plastic material;

a pyrolysis reactor configured to receive and heat the molten waste plastic material to a temperature of 390°C to 410°C to form pyrolysis gases;

one or more condensers configured to receive and cool the pyrolysis gases into fractions for recovery as fuel products.

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7. The plant of claim 6, wherein the heated extruder is configured to heat the waste plastic material to a temperature of 280°C to 320°C to form the molten plastic material.

8. The plant of claim 6 or 7, wherein the fuel products comprise at least a majority by weight diesel fuel products.

9. The plant of any one of claims 6 to 8, wherein the fuel products comprise fuel products with carbon chains of a length between C6 and C25, peaking at C16.

10. The plant of any one of claims 6 to 9, wherein the fuel products are substantially equivalent to diesel fuels specified in Australian Standard AS 3570-1998.

11. A fuel product made by the process of any one of claims 1 to 5, or the plant of any one of claims 6 to 10.