WO2022130237A1

WO2022130237A1 - A pyrolysis process

Info

Publication number: WO2022130237A1
Application number: PCT/IB2021/061765
Authority: WO
Inventors: Musa Schuster MSIMANGO; Victor van Zyl TAYLOR; Daniel Johannes Jacobus PRETORIUS
Original assignee: Phambili Energy (Pty) Ltd.
Priority date: 2020-12-18
Filing date: 2021-12-15
Publication date: 2022-06-23

Abstract

A continuous process (10) for the production of a pyrolysis oil (42, 44, 46) includes continuously feeding a particulate carbonaceous material into a first pyrolysis zone (14), thermally decomposing the carbonaceous material in the first pyrolysis zone (14), at a temperature T1 between 140°C and 180°C, in an inert atmosphere, to produce a gas and a solid residue, and condensing (28.1, 28.2) at least a portion of the gas at a temperature of at least 6°C to produce a first pyrolysis oil (42). The solid residue is thermally decomposed further in an inert atmosphere in at least one further pyrolysis zone (16) at a temperature T2 of at least 240°C to produce a gas and a solid residue. At least a portion of the gas from the at least one further pyrolysis zone (16) is condensed (28.3, 28.4) to provide a second pyrolysis oil (44), and solid residue is continuously withdrawn from the further pyrolysis zone (16).

Description

A PYROLYSIS PROCESS

THIS INVENTION RELATES TO a pyrolysis process. In particular, the invention relates to a continuous pyrolysis process for the production of a pyrolysis oil, to a pyrolysis oil produced by the process, and to a pyrolysis oil with a desired composition.

Pyroligneous acid, also known as wood vinegar, is one form of a pyrolysis oil or bio-oil conventionally produced by the destructive distillation, i.e. pyrolysis, of wood and other plant materials. Typically, wood vinegar comprises 80 to 90%, or even up to 95% by weight water, acetic acid, acetone and methanol, and about 200 other organic compounds, including ethanol. The presence of methanol and ethanol however limits the uses of wood vinegar, e.g. in fracking, as it renders the wood vinegar flammable, or in pesticide formulations, where the presence of ethanol at least at initial formulation stages may be undesirable. A pyrolysis process for producing a pyrolysis oil or bio-oil such as wood vinegar that is free of, or has very low concentrations of, methanol and ethanol, whilst still being economically viable, would thus be attractive.

According to the invention, there is provided a continuous process for the production of a pyrolysis oil, the process including continuously feeding a particulate carbonaceous material into a first pyrolysis zone; thermally decomposing the carbonaceous material in the first pyrolysis zone, at a temperature T1 between about 140°C and about 180°C, in an inert atmosphere, to produce a gas and a solid residue; condensing at least a portion of the gas at a temperature of at least about 6°C to produce a first pyrolysis oil; thermally decomposing the solid residue further in an inert atmosphere in at least one further pyrolysis zone at a temperature T2 of at least about 240°C to produce a gas and a solid residue; condensing at least a portion of the gas from the at least one further pyrolysis zone to provide a second pyrolysis oil; and continuously withdrawing solid residue from the further pyrolysis zone. Advantageously, the first pyrolysis oil, which may be a wood vinegar, is typically free of methanol and free of ethanol, with the second pyrolysis oil being a saleable or useful (e.g. as fuel for heating purposes in the process of the invention) bio-oil or tar, and with the solids residue, as is or after further treatment, being a valuable char product or activated charcoal product, so that the production of the second pyrolysis oil or bio-oil or tar and the char or activated carbon assists in rendering the production of the first pyrolysis oil economically attractive.

In this specification, "free of methanol" and "free of ethanol" are intended respectively to indicate a methanol content or an ethanol content of less than 0.3% by mass, preferably less than 0.2% by mass, more preferably less than 0.1 % by mass.

In this specification, by "inert atmosphere" is meant an atmosphere which is substantially free of oxygen, preferably having less than 6% by mass oxygen, more preferably having less than 5% by mass oxygen, most preferably having less than 4 % by mass oxygen, e.g. having about 3% by mass oxygen.

The inert atmosphere in the pyrolysis zones is typically at atmospheric pressure, or slightly below atmospheric pressure. One or more induced draft fans may be employed to remove gas from the pyrolysis zones, which may thus cause the pressure in the pyrolysis zones to be slightly less than atmospheric.

Preferably, the temperature T1 in the first pyrolysis zone is between about 145°C and about 175°C, more preferably between about 150°C and about 170°C, e.g. about 150°C.

The carbonaceous material fed to the first pyrolysis zone may be selected from the group consisting in wood, sawdust, grass, agricultural waste, sewage sludge, biomass, rubber, rubber from tyres, paper, and plastics materials. As will be appreciated, depending on the nature of the carbonaceous material, i.e. whether the particulate carbonaceous material is wood or derived from wood, the first pyrolysis oil may be a wood vinegar, or a product which more accurately is described merely as a pyrolysis oil or bio-oil. The particulate carbonaceous material may have a particle size between about 0.5mm and about 10mm₇ preferably between about 1mm and about 10mm, more preferably between about 2mm and about 10mm, e.g. between about 4mm and about 10mm, or between about 6mm and about 10mm, such as about 8mm.

The process may include pelletising or granulating a fine particulate carbonaceous material, e.g. sawdust, if necessary or desirable, to provide the particulate carbonaceous material with a desired particle size.

The particulate carbonaceous material may have a residence time in the first pyrolysis zone of between about 12 minutes and about 25 minutes, preferably between about 15 minutes and about 25 minutes, e.g. about 20 minutes.

The first pyrolysis zone may be defined by a kiln.

The at least one further pyrolysis zone may be defined by a kiln.

The first pyrolysis zone and the at least one further pyrolysis zone may be defined by the same kiln.

The kiln may be a horizontal kiln. Typically, the kiln is elongate and stationary, i.e. non-rotating about a longitudinal axis thereof.

Typically, an auger or screw conveyor or screw feeder or the like is used to convey the carbonaceous material and solid residue continuously through the kiln.

The pyrolysis zones may be heated externally, e.g. using burners such as diesel burners or bio-oil burners. In one embodiment of the invention, the kiln is double-walled, with an inner wall defining an elongate cylindrical, e.g. elongate circular cylindrical, volume within which the pyrolysis zones are located, and with burners heating plenum volumes defined between the inner wall and an outer wall or jacket. Indirect heating by means of heat transfer through the inner wall is thus employed in this embodiment thermally to decompose the carbonaceous material or solid residue, as the case may be, in the pyrolysis zones.

Heating the pyrolysis zones, e.g. externally, may be effected intermittently. Thermally decomposing the carbonaceous material may thus include relying at least to some extent on exothermic reactions in the pyrolysis zones to generate the heat required thermally to decompose the carbonaceous material or solid residue, as the case may be.

The process thus typically includes controlling the temperature in each pyrolysis zone. Controlling the temperature in a pyrolysis zone may include manipulating one or more of the moisture content of the particulate carbonaceous material, the particle size of the particulate carbonaceous material, the rate at which particulate carbonaceous material or solid residue, as the case may be, is fed into a pyrolysis zone, and heat input into a pyrolysis zone.

The particulate carbonaceous material may have a moisture content of between about 0% and about 9% by mass, typically between about 3% by mass and about 9% by mass, more typically between about 3% by mass and about 6% by mass, e.g. about 5% by mass.

The temperature T2 may be less than about 300°C.

Preferably, the temperature T2 in the at least one further pyrolysis zone is between about 245°C and about 290°C, more preferably between about 250°C and about 280°C, e.g. about 250°C.

The gas from the first pyrolysis zone may be condensed at a temperature of no more than about 30°C.

Preferably, the gas from the first pyrolysis zone is condensed at a temperature of between about 6°C and about 20°C, e.g. about 18°C.

The gas from the at least one further pyrolysis zone may be condensed at a temperature of not less than about 6°C. The gas from the at least one further pyrolysis zone may be condensed at a temperature of no more than about 30°C.

The gas from the at least one further pyrolysis zone is preferably condensed at a temperature of between about 6°C and about 20°C, e.g. about 18°C.

The solid residue may have a residence time in the second pyrolysis zone of between about 12 minutes and about 25 minutes, preferably between about 15 minutes and about 25 minutes, e.g. about 20 minutes.

The first pyrolysis zone may be a low temperature pyrolysis zone and the second pyrolysis zone may be a medium temperature pyrolysis zone, with the process including thermally decomposing the solid residue from the medium temperature pyrolysis zone further in a high temperature pyrolysis zone at a temperature T3 of between about 350°C and about 400°C, to produce a gas and a solid residue in the form of char.

Preferably, the temperature T3 in the high temperature pyrolysis zone is between about 360°C and about 390°C, more preferably between about 370°C and about 390°C, e.g. about 380°C.

The high temperature pyrolysis zone may be defined by the same kiln defining the low temperature pyrolysis zone and the medium temperature pyrolysis zone. Thus, typically, solid residue is continuously fed from the medium temperature pyrolysis zone into the high temperature pyrolysis zone. Preferably, the pyrolysis zones are immediately adjacent one another, with solid residue being transferred between adjacent pyrolysis zones acting to inhibit movement of gas produced in one pyrolysis zone into an adjacent pyrolysis zone.

The solid residue may have a residence time in the high temperature pyrolysis zone of between about 12 minutes and about 25 minutes, preferably between about 15 minutes and about 25 minutes, e.g. about 20 minutes. Typical ly, the process includes condensing at least a portion of the gas from the high temperature pyrolysis zone to form a third pyrolysis oil, which is typically a tar or viscous bio-oil product at room temperature.

The gas from the high temperature pyrolysis zone may be condensed at a temperature of not less than about 6°C.

The gas from the high temperature pyrolysis zone may be condensed at a temperature of no more than about 30°C.

Preferably, the gas from the high temperature pyrolysis zone is condensed at a temperature between about 6°C and about 20°C, e.g. about 18°C.

Advantageously, as will be appreciated, the process of the invention may thus employ plant cooling water as a cooling medium to satisfy all of the condensing duty, thus avoiding the cost of a chiller or the like to produce a cooling medium at a temperature lower than that of typical plant cooling water.

Typically, at least some of the pyrolysis zones employ at least two condensers arranged in series relative to gas flow to condense gas withdrawn from the pyrolysis zones.

The condensers are typically elongate shell-and-tube condensers, with the gas being tube-side and the cooling medium being shell-side.

Preferably, the process includes removing dust from gas withdrawn from a pyrolysis zone, prior to condensing at least a portion of the gas. Any conventional technique suitable for removing particulate material from a hot stream of gas may be employed, e.g. cyclonic separators.

Dust removed from gas withdrawn from a pyrolysis zone may be combined with solid residue in the form of char produced by the process. The char and dust may be processed to form briquettes, or to provide an activated charcoal product. The process may include drying the particulate carbonaceous material to a desired moisture content as hereinbefore described, before feeding the particulate carbonaceous material into the first pyrolysis zone.

The particulate carbonaceous material may be dried at a temperature of between about 100°C and about 120°C, e.g. about 110°C.

In one embodiment of the invention, the particulate carbonaceous material is dried using hot exhaust gas from the burners of the kiln. Typically, this drying is effected by means of direct heat exchange between the gas and the particulate carbonaceous material.

If necessary, the process may employ additional heating means, e.g. dedicated diesel burners, to dry the particulate carbonaceous material.

The process may include condensing gas produced by the drying of the particulate carbonaceous material, to produce an essential oils or phenols product.

The process typically includes producing uncondensed gas. Such uncondensed gas may thus be withdrawn from condensers used to condense a portion of the gas from each pyrolysis zone. Typically, the gas withdrawn from all of the condensers is combined to form a pyrolytic gas. Advantageously, the pyrolytic gas can be used for heating or drying purposes by combustion of the gas, or to generate power, e.g. electrical power.

The pyrolytic gas obtained from condensers used to condense a portion of the gas from each pyrolysis zone and combined, may have a calorific value of between about 5 MJ/kg and 10 MJ/kg, e.g. about 7.5 MJ/kg.

Solid residue, e.g. char, produced by the process is typically cooled to a temperature of between about 6°C and about 30°C, preferably between about 10°C and about 30°C, e.g. about 25°C, before the solid residue is exposed to oxygen, e.g. ambient air. Cooling is typically effected with indirect heat exchange with cooling air or cooling water. The char from the high temperature pyrolysis zone may have a fixed carbon content of between about 70% by mass and about 95% by mass, typically between about 73% by mass and about 85% by mass, more typically between 75% by mass and about 80% by mass, e.g. about 76% by mass, on a dry basis. As will be appreciated, this char can advantageously be used as a fertilizer, as a soil stabiliser, and in briquettes as a fuel.

The char from the high temperature pyrolysis zone may have a calorific value of between about 28 MJ/kg and about 31 MJ/kg, e.g. about 30 MJ/kg.

The invention extends to a first pyrolysis oil produced by the process as hereinbefore described.

The first pyrolysis oil may be free of ethanol.

The first pyrolysis oil may be free of methanol.

The first pyrolysis oil may be non-flammable.

The invention furthermore extends to a wood vinegar which is free of ethanol.

Typically, the wood vinegar is also free of methanol.

The first pyrolysis oil or wood vinegar may have a pH between about 2 and about 4, e.g. about 2.6 or about 3.3.

The wood vinegar may be non-flammable.

The first pyrolysis oil or wood vinegar, as the case may be, may have an organic acid content of between about 2% by mass and about 5% by mass, or between about 3% by mass and about 5% by mass, e.g. about 4% by mass. The first pyrolysis oil or wood vinegar, as the case may be, may comprise acetic acid as major organic component.

The invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawing which shows a process in accordance with the invention to produce a pyrolysis oil.

Referring to the drawing, reference numeral 10 generally indicates a process in accordance with the invention for the production of a pyrolysis oil.

The process 10 comprises a horizontal kiln 12 defining a first or low temperature pyrolysis zone 14, a second or medium temperature pyrolysis zone 16 and a third or high temperature pyrolysis zone 18. The pyrolysis zones 14, 16 and 18 have the same size or length, ensuring the same residence time in each of these zones 14, 16, 18 for solids materials passing through the zones 14, 16 and 18.

The process 10 further includes a particulate carbonaceous material dryer 20, an optional off-gas condenser 22, three cyclonic separators 24.1, 24.2 and 24.3, a char cooler 26, and six pyrolysis oil condensers 28.1 to 28.6.

A particulate carbonaceous material feed line 30 leads from a stockpile of particulate carbonaceous material (not shown) into the particulate carbonaceous material dryer 20 and from the particulate carbonaceous material dryer 20 to the kiln 12. A char line 32 leads from the kiln 12 to the char cooler 26, with a char product line 34 leading from the char cooler 26.

Pyrolysis gas lines 36.1, 36.2 and 36.3 respectively lead from the low temperature pyrolysis zone 14, the medium temperature pyrolysis zone 16 and the high temperature pyrolysis zone 18, respectively to the cyclonic separators 24.1, 24.2 and 24.3. A dust line 38 leads from each of the cyclonic separators 24.1, 24.2 and 24.3 and joins the char line 32, upstream of the char cooler 26. Cleaned pyrolysis gas lines 40.1, 40.2 and 40.3 lead respectively from the cyclonic separators 24.1, 24.2 and 24.3 and respectively to the pyrolysis oil condensers 28.1 and 28.2, 28.3 and 28.4, and 28.5 and 28.6. A first pyrolysis oil product line 42 leads from the condenser 28.2, a second pyrolysis oil product line 44 leads from the pyrolysis oil condenser 28.4 and a third pyrolysis oil product line 46 leads from the pyrolysis oil condenser 28.6.

Pyrolytic gas withdrawal lines 48.1, 48.2 and 48.3 respectively lead from the pyrolysis oil condensers 28.2, 28.4 and 28.6.

The kiln 12 is double-walled, having an elongate circular cylindrical wall 50 or pipe defining an elongate circular cylindrical volume within which an electrically driven auger 52 is rotatably located, and an outer wall or jacket 54 spaced from the inner wall 50 and defining plenum volumes 56.1, 56.2 and 56.3. The plenum volumes 56.1 and 56.2 are separated by a baffle wall 58 and the plenum volumes 56.2 and 56.3 are separated by a baffle wall 60. Each plenum volume 56.1, 56.2 and 56.3 has a plurality of diesel burners 62 for heating their associated plenum volumes 56.1, 56.2 and 56.3, and hence the low temperature pyrolysis zone 14, the medium temperature pyrolysis zone 16 and the high temperature pyrolysis zone 18.

Diesel exhaust gas withdrawal lines 62 lead from the plenum volumes 56.1, 56.2 and 56.3 to the particulate carbonaceous material dryer 20, and from the particulate carbonaceous material dryer 20 to the optional off-gas condenser 22. The off-gas condenser 22 is provided with a vent line 64 and an essential oils or phenols product line 66.

In order to produce pyrolysis oil, a particulate carbonaceous feed material, e.g. in the form of sawdust from both pine and blue gum trees and bark, with a particle size of between about 0.6mm and about 6.7mm, is continuously fed to the dryer 20 by means of the particulate carbonaceous material feed line 30, which may for example be in the form of a screw feeder or a conveyor belt or a pneumatic feed line or the like.

In the dryer 20, the carbonaceous feed material is dried to a moisture content of

5% by mass, at a temperature of about 110°C, using hot diesel exhaust gas at a temperature of about 120°C fed to the dryer 20 by means of the diesel exhaust gas line 62. If necessary, the dryer 20 employs additional diesel burners to satisfy the drying duty required.

From the dryer 20, the dried carbonaceous feed material is continuously fed by means of the particulate carbonaceous material feed line 30 to the kiln 12, where it is discharged into the first or low temperature pyrolysis zone 14 (typically via a hopper, which is not shown, with the carbonaceous material feed line 30 between the dryer 20 and the hopper, and between the hopper and the kiln 12, being in the form of screw feeders or conveyor belts not open to the atmosphere), and then slowly, continuously transferred first through the low temperature pyrolysis zone 14, and then the medium temperature pyrolysis zone 16, and finally the high temperature pyrolysis zone 18, by means of the electrically driven auger 52.

As will be appreciated, the use of a hopper and screw feeders or conveyor belts not open to the atmosphere essentially prevents ingress of air into the kiln 12 together with the dried carbonaceous feed material. This renders the atmosphere inside the low temperature pyrolysis zone 14, the medium temperature pyrolysis zone 16, and the high temperature pyrolysis zone 18 inert.

The pyrolysis zones 14, 16, 18 are heated externally by means of the diesel burners 62, as required, to ensure a desired temperature in each of the pyrolysis zones 14, 16, 18. In other words, the diesel burners 62 heat the plenum volumes 56.1, 56.2 and 56.3, with heat transfer through the inner wall 50 leading to the heating of the pyrolysis zones 14, 16, 18. One or more programmable logic controllers (not shown) are used accurately to control the temperature in each of the pyrolysis zones 14, 16, 18 to within about 10°C of a set point temperature for each pyrolysis zone 14, 16 and 18. The PLC's may be programmed to manipulate one or more of the moisture content of the carbonaceous feed material, the particle size of the particulate carbonaceous material (when the process 10 includes a unit operation which produces particulate carbonaceous material with a controllable particle size, e.g. a pelletising operation or a wood chipping operation), the rate at which particulate carbonaceous material, e.g. wood chips, or solid residue, as the case may be, is fed into and from a pyrolysis zone 14, 16, 18, and heat input into a pyrolysis zone 14, 16, 18. Diesel exhaust gas is withdrawn from the plenum volumes 56.1, 56.2 and 56.3 by means of the diesel exhaust gas lines 62 and fed to the particulate carbonaceous material dryer 20 for purposes of drying the carbonaceous feed material fed to the process 10. As mentioned hereinbefore, if necessary, additional diesel burners are employed in the dryer 20 to ensure that the carbonaceous feed material has a sufficiently low moisture content.

The diesel exhaust gas from the dryer 20 is withdrawn by means of the diesel exhaust gas line 62 and fed to the off-gas condenser 22, where the diesel exhaust gas is partially condensed to condense volatile material driven off from the carbonaceous feed material during drying, using plant cooling water as cooling medium, thereby to produce an essential oils or phenols product which is withdrawn by means of the essential oils or phenols product line 62, and uncondensed, cooled exhaust gas which is vented to atmosphere via the vent line 64.

In the low temperature pyrolysis zone 14, the carbonaceous feed material is subjected to pyrolysis conditions at a temperature of about 150°C, for a time period of about 20 minutes, at a pressure which is only slightly below atmospheric pressure, in an inert atmosphere.

In the low temperature pyrolysis zone 14, the carbonaceous feed material is thus subjected to incomplete thermal decomposition or pyrolysis in an inert atmosphere at a relatively low pyrolysis temperature, producing a pyrolysis gas and a solid residue. The solid residue is continuously transferred from the low temperature pyrolysis zone 14 by means of the auger 52 into the medium temperature pyrolysis zone 16. In the medium temperature pyrolysis zone 16, the solid residue is thermally decomposed further at a temperature of about 250°C in an inert atmosphere, for a time period of about 20 minutes, producing more pyrolysis gas and a solid residue, with the solid residue from the medium temperature pyrolysis zone 16 having a higher carbon content than the solid residue from the low temperature pyrolysis zone 14. Also in the medium temperature pyrolysis zone 16, the atmosphere is thus inert and at a pressure only slightly less than atmospheric pressure.

Solid residue from the medium temperature pyrolysis zone 16 is continuously transferred by means of the auger 52 to the high temperature pyrolysis zone 18, where the solid residue is subjected to thermal decomposition in an inert atmosphere at a temperature of about 380°C, for a time period of about 20 minutes, producing even more pyrolysis gas and a char with a carbon content of about 76 % by mass. The char from the high temperature pyrolysis zone 18 is continuously withdrawn by means of the char line 32 (typically in the form of a screw feeder or conveyor belt that is not open to the atmosphere to prevent air ingress) and fed to the char cooler 26.

As mentioned, as a result of the thermal decomposition of the carbonaceous feed material in the low temperature pyrolysis zone 14, medium temperature pyrolysis zone 16 and high temperature pyrolysis zone 18, pyrolysis gas is produced. The pyrolysis gas from the low temperature pyrolysis zone 14, the medium temperature pyrolysis zone 16 and the high temperature pyrolysis zone 18 is respectively withdrawn by means of the pyrolysis gas lines 36.1, 36.2 and 36.3 (and induced draft fans (not shown) in the pyrolytic gas withdrawal lines 48.1, 48.2 and 48.3), kept separate and respectively fed to the cyclonic separators 24.1, 24.2 and 24.3. In the cyclonic separators 24.1, 24.2 and 24.3, dust (mostly carbon or charcoal dust) is separated from the gas, with the separated dust being transferred by means of the dust line 38 to the char line 32, where the dust is mixed with the char. The dust and char are then cooled in the char cooler 26 to a temperature below 30°C, using plant cooling water as a cooling medium, producing a char or biochar product which is withdrawn by means of the char product line 34.

The char product is valuable as it has a fixed carbon content of about 76% by mass and a calorific value of about 30 MJ/kg. The production of the char or biochar product improves the economic feasibility of the process of the invention, as illustrated. The char product can be briquetted using a suitable binder, for sale as a fuel, or can be activated using steam and sold as an activated charcoal product.

Cleaned pyrolysis gas is withdrawn from each of the cyclonic separators 24.1, 24.2 and 24.3, by means of the clean pyrolysis gas lines 40.1, 40.2 and 40.3, and fed to the pyrolysis oil condensers 28.1, 28.3 and 28.5, and from there to the pyrolysis oil condensers 28.2, 28.4 and 28.6. In the pyrolysis oil condensers 28.1 to 28.6, the clean pyrolysis gas is partially condensed, using plant cooling water as a cooling medium, producing a first pyrolysis oil product withdrawn by means of the first pyrolysis oil product line 42, a second pyrolysis oil product withdrawn by means of the second pyrolysis oil product line 44, and a third pyrolysis oil product, which is a viscous fluid or tar at room temperature, withdrawn by means of the third pyrolysis oil product line 46.

Uncondensed pyrolytic gas is withdrawn from each of the pyrolysis oil condensers

28.2, 28.4 and 28.6 respectively by means of the pyrolytic gas withdrawal lines 48.1, 48.2 and

48.3. Typically, the gas from the lines 48.1, 48.2 and 48.3 is combined and used for heating or drying purposes in the process 10, or to generate power, e.g. electrical power. Advantageously, the combined pyrolytic gas has a calorific value in the range of about 5 - 10 MJ/kg.

The pyrolysis oil condensers 28.1 to 28.6 are all elongate counter-current shell- and-tube condensers, arranged in pairs in series as far as the flow of cleaned pyrolysis gas is concerned, with the cleaned pyrolysis gas being on the tube-side and with plant cooling water being shell-side. As plant cooling water is used in each of the pyrolysis oil condensers 28.1 to 28.6, it will be appreciated that the cleaned pyrolysis gas passing through these condensers is condensed at a temperature of about 20°C.

For illustrative purposes, Table 1 below provides an analysis of the first pyrolysis oil, in the form of a wood vinegar, produced by the process 10, as illustrated, using particulate pine wood as feed material. The analysis provides information on the concentration of certain elements, with additional information such as pH, conductivity and moisture content.

Table 1: Elemental analysis of wood vinegar produced from particulate pine wood

For purposes of additional illustration, the following information is also provided.

A second pyrolysis oil with the properties shown in Tables 2, 3 and 4, a biochar with the properties shown in Table 5, and a wood vinegar with the properties shown in Tables 6, 7 and 8, were produced from pine and blue gum tree sawdust and bark with the properties shown in Tables 9 and 10, using the process 10.

Table 2: Properties of the second pyrolysis oil

Table 3: Typical compound groups, including derivatives, found in the second pyrolysis oil, using

GC-MS analysis

Table 4: GC-MS analysis results for two different samples of the second pyrolysis oil

Table 5: Proximate and ultimate analysis of the bio-char

DB & DAF H & 0 values

Hydrogen (excludes H in moisture) % - 2.87 exclude H & 0 in moisture

Table 6: Properties of the first pyrolysis oil or wood vinegar

Table 7: Typical compound groups, including derivatives, found in the first pyrolysis oil, using

GC-MS analysis

Table 8: GC-MS analysis results for two different samples of the first pyrolysis oil or wood vinegar

Table 9: Sawdust particle size analysis

Table 10: Proximate and ultimate analysis of the sawdust

The first pyrolysis oil withdrawn by means of the first pyrolysis oil product line 48.1 is of particular value. The first pyrolysis oil, produced by the process 10, is typically essentially free of methanol and ethanol and thus non-flammable. When the particulate carbonaceous material fed to the process 10 is a ligneous material, e.g. wood chips or pelletised sawdust or the like, the first pyrolysis oil is a wood vinegar, which advantageously and unusually is substantially free of methanol and ethanol. The non-flammable first pyrolysis oil or wood vinegar can be used for green fracking, replacing the slick water typically used in these processes, with a combination of the first pyrolysis oil, red/craft liquor and a catalyst to liquify and separate tar sand from crude tar, as well as for post- and pre-treatment in oil wells. The first pyrolysis oil can also be used as an organic alternative to hydrochloric acid in some processes. In some embodiments of the process of the invention, the first pyrolysis oil produced has the ability to dissolve carbonite geologies/sandstone in gold and diamond mining. It can also be used as an antimicrobial agent or as an active ingredient in C4L technology in agriculture as an organic herbicide or pesticide. Furthermore, the first pyrolysis oil can be a source of organic carbon and can provide phenols for medical applications.

The production of the second and third pyrolysis oils, and optionally the essential oils or phenols product, improves the economic feasibility of the process of the invention, as illustrated. The pyrolysis oils in general can be used as fuel for heating or power generation, and as feedstock in the manufacture of resins, fertilisers, ascetic acid, flavourants, and adhesives.

Claims

22 Claims

1. A continuous process for the production of a pyrolysis oil, the process including continuously feeding a particulate carbonaceous material into a first pyrolysis zone; thermally decomposing the carbonaceous material in the first pyrolysis zone, at a temperature T1 between 140°C and 180°C, in an inert atmosphere, to produce a gas and a solid residue; condensing at least a portion of the gas at a temperature of at least 6°C to produce a first pyrolysis oil; thermally decomposing the solid residue further in an inert atmosphere in at least one further pyrolysis zone at a temperature T2 of at least 240°C to produce a gas and a solid residue; condensing at least a portion of the gas from the at least one further pyrolysis zone to provide a second pyrolysis oil; and continuously withdrawing solid residue from the further pyrolysis zone.

2. The process according to claim 1, wherein the first pyrolysis oil is a wood vinegar and wherein the wood vinegar is free of methanol and free of ethanol.

3. The process according to claim 1 or claim 2, wherein the temperature T1 in the first pyrolysis zone is between 145°C and 175°C, or between about 150°C and about 170°C.

4. The process according to any of claims 1 to 3, wherein the particulate carbonaceous material has a residence time in the first pyrolysis zone of between 12 minutes and 25 minutes, or between 15 minutes and 25 minutes.

5. The process according to any of claims 1 to 4 wherein the first pyrolysis zone is defined by a kiln, or wherein the at least one further pyrolysis zone is defined by a kiln, or wherein the first pyrolysis zone and the at least one further pyrolysis zone are defined by a common horizontal kiln.

6. The process according to claim 5, wherein the common horizontal kiln is elongate and stationary, i.e. non-rotating about a longitudinal axis thereof, and wherein an auger or screw conveyor or screw feeder is used to convey the carbonaceous material and solid residue continuously through the kiln.

7. The process according to any of claims 1 to 6, wherein the pyrolysis zones are heated externally, or wherein heating of the pyrolysis zones is effected intermittently.

8. The process according to any of claims 1 to 7, wherein the temperature T2 in the at least one further pyrolysis zone is less than 300°C, or wherein the temperature T2 in the at least one further pyrolysis zone is between 245°C and 290°C, or between 250°C and 280°C.

9. The process according to any of claims 1 to 8, wherein the gas from the at least one further pyrolysis zone is condensed at a temperature of not less than 6°C.

10. The process according to any of claims 1 to 9, wherein the first pyrolysis zone is a low temperature pyrolysis zone and the second pyrolysis zone is a medium temperature pyrolysis zone, the process including thermally decomposing the solid residue from the medium temperature pyrolysis zone further in a high temperature pyrolysis zone at a temperature T3 of between 350°C and 400°C, to produce a gas and a solid residue in the form of char.

11. The process according to claim 10, wherein the temperature T3 in the high temperature pyrolysis zone is between 360°C and 390°C, or between 370°C and 390°C.

12. The process according to claim 5 and claim 10, wherein the high temperature pyrolysis zone is defined by the same kiln defining the low temperature pyrolysis zone and the medium temperature pyrolysis zone, with solid residue being continuously fed from the medium temperature pyrolysis zone into the high temperature pyrolysis zone, and wherein the pyrolysis zones are immediately adjacent one another, with solid residue being transferred between adjacent pyrolysis zones acting to inhibit movement of gas, produced in one pyrolysis zone, into an adjacent pyrolysis zone.

13. The process according to any of claims 10 to 12, which includes condensing at least a portion of the gas from the high temperature pyrolysis zone to form a third pyrolysis oil.

14. The process according to claim 13, wherein the gas from the high temperature pyrolysis zone is condensed at a temperature of not less than 6°C.

15. The process according to any of claims 1 to 14, which includes removing dust from gas withdrawn from a pyrolysis zone, prior to condensing at least a portion of the gas, combining said dust with solid residue in the form of char produced by the process, and processing the char and dust to form briquettes, or to provide an activated charcoal product.

16. A first pyrolysis oil produced by the process of any of claims 1 to 15, which is free of ethanol, or a wood vinegar which is free of ethanol.

17. The first pyrolysis oil or the wood vinegar according to claim 16, which is also free of methanol.

18. The first pyrolysis oil or the wood vinegar according to claim 16 or claim 17, which has a pH between 2 and 4, or which is non-flammable.

19. The first pyrolysis oil or the wood vinegar according to any of claims 16 to 18, which has an organic acid content of between 2% by mass and 5% by mass, or between 3% by mass and 5% by mass.

20. The first pyrolysis oil or the wood vinegar according to any of claims 16 to 19, which comprise acetic acid as major organic component.