Method for producing high value chemicals from feedstocks

Abstract

A method of producing a high value chemical from a feedstock, wherein the feedstock is a waste material or comprises a waste material. A fluidized reactor system is provided comprising a pyrolysis chamber (2) and a combustion chamber (12). The feedstock is fed into the pyrolysis chamber and a pyrolysis process is performed at a temperature in the range of from 650 DEG C to 850 DEG C to obtain a product gas comprising high value chemicals.

Description

Technical Field

[0001] The present invention relates to an improved process for producing high-value chemicals from feedstocks. More specifically, the present invention relates to an improved process for producing high-value chemicals from waste materials. More specifically, the improved process is used to increase the yield of olefins, monocyclic aromatic compounds, or combinations thereof and reduce side reactions and the level of pollutants present in the product gas. Background Art

[0002] WO 2003 / 018723 discloses a method and a device for purifying synthesis gas obtained during the gasification of biomass. The synthesis gas is passed through a saturation unit and an absorption unit, both of which are fed with oil. The oil is used as a scrubbing agent to remove tar from the synthesis gas.

[0003] WO 2018 / 208163 discloses a method and apparatus for removing monocyclic aromatic compounds from a gas. The gas is contacted with a scrubbing liquid to obtain a purified gas and a spent scrubbing liquid containing dissolved monocyclic aromatic compounds. The spent scrubbing liquid is stripped with steam, and the monocyclic aromatic compounds are separated by condensation and further decantation.

[0004] US2020 / 0362248 discloses a method and apparatus for producing olefins and aromatic compounds by catalytic pyrolysis of polymers. A heat-forming additive is used to provide sufficient heat during catalyst regeneration.

[0005] US10093860 discloses a method and apparatus for treating waste including mixed plastic waste. The method comprises feeding the waste into a pyrolysis reactor to produce fuel and using the fuel to operate a generator to generate electricity.

[0006] WO 2008 / 108644 and WO 2014 / 070001 disclose devices for producing product gas from biomass. The fuel (e.g. biomass) supplied to the riser in the reactor typically contains 80% by weight of volatile components and 20% by weight of substantially solid carbon or char. The biomass supplied to the riser is heated to a temperature above 800°C, such as between 850°C-900°C, in a low oxygen or oxygen-free environment, resulting in pyrolysis of the biomass and production of product gas. Solid carbon and char undergo only a limited degree of pyrolysis, and it is therefore necessary to burn such material in a separate combustion zone of the reactor.

[0007] It is therefore an object of various aspects of the present invention to address one or more of the above or other problems. Summary of the invention

[0008] In one aspect, the present invention relates to a method for producing high-value chemicals from a feedstock, wherein the feedstock is or contains waste, the method comprising: (a) providing a fluidized reactor system comprising a pyrolysis chamber and a combustion chamber, and (b) inputting the feedstock into the pyrolysis chamber and performing a pyrolysis process at a temperature ranging from 650° C. to 850° C. to obtain a product gas containing high-value chemicals.

[0009] Furthermore, all defining features of the method according to the invention also apply to the use according to the invention and vice versa.

[0010] The method according to the invention enables the pyrolysis of waste materials at sufficiently low temperatures to provide an optimized yield of high-value chemicals and a reduction in by-products. Another advantage of the method is that the raw material can be a mixture of biomass and plastics and is therefore inexpensive, for example, and does not require intensive separation before use.

[0011] The waste material may be municipal solid waste.

[0012] The waste material is preferably biomass, biomass-rich refuse derived fuel, plastic-rich refuse derived fuel and plastic or a combination thereof. Biomass may be close to 100% biogenic, biomass-rich refuse derived fuel is typically from 50% to 70% biogenic, plastic-rich refuse derived fuel is typically from 50% to 75% non-biogenic, and plastic is typically from 75% to 100% non-biogenic.

[0013] The waste preferably comprises plastic material. The waste may comprise from 30% to 100% plastic by weight of the waste. For example, the refuse derived fuel may comprise from 50% to 80% plastic by total weight of the refuse derived fuel. Increasing the amount of plastic in the waste in turn increases the amount of high value chemicals such as olefins.

[0014] Anthropogenic carbon may be present in the waste material at from 40% to 100%, preferably from 60% to 90% by weight of the waste material.

[0015] The waste material may have a moisture content of from 5% to 30%, preferably from 10% to 25%, by weight of the waste material. Providing said moisture content facilitates feeding the plastic into the pyrolysis chamber. Providing waste material with a moisture content above 30% will reduce the operating temperature of the combustion chamber to an ineffective level.

[0016] Preferably, the high-value chemicals in the product gas are olefins and / or monocyclic aromatic compounds. Olefins can be ethylene, propylene, C 4 Olefins, C 5 Olefins, C 5+ Olefins or combinations thereof. Preferably, the olefins are ethylene, propylene, C 4 Olefins, C5 Even more preferably, the olefin is ethylene, propylene, C 4 Olefins or combinations thereof. The monocyclic aromatic compound may be benzene, toluene, styrene, ethylbenzene, xylene or a combination thereof. More specifically, the monocyclic aromatic compound may be benzene, toluene, styrene, ethylbenzene, m-xylene, p-xylene or a combination thereof. Preferably, the monocyclic aromatic compound is benzene, toluene, xylene, styrene or a combination thereof.

[0017] In a preferred embodiment, the olefin is ethylene, propylene, C 4 Olefins, C 5 The olefin or a combination thereof, and / or the monocyclic aromatic compound is benzene, toluene, xylene, styrene or a combination thereof. More preferably, the olefin is ethylene, propylene, C 4 Or a combination thereof, and / or the monocyclic aromatic compound is benzene, toluene, xylene or a combination thereof. Even more preferably, the olefin is ethylene, propylene or a combination thereof, and / or the monocyclic aromatic compound is benzene, toluene, xylene or a combination thereof.

[0018] The product gas may contain from 30% to 70%, preferably 45% to 60% olefins by weight of the product gas. The product gas may contain from 5% to 25%, preferably from 10% to 20%, even more preferably from 12% to 18% monocyclic aromatic compounds by weight of the product gas.

[0019] The method may further include circulating the bed material from the combustion chamber to the pyrolysis chamber via the conveying zone, and performing a pyrolysis process and a combustion process in the bed material, wherein when the bed material is circulated, sufficient heat is transferred from the combustion chamber to the pyrolysis chamber to perform the pyrolysis process. This enables the heat generated in the combustion chamber to be transferred to the pyrolysis chamber via the circulation of the bed material. The bed material is preferably continuously circulated from the combustion chamber to the pyrolysis chamber via a closed system or loop. In other words, the bed material is preferably continuously circulated via a closed loop between the combustion chamber and the pyrolysis chamber.

[0020] The temperature difference between the combustion chamber and the pyrolysis chamber can be increased by reducing the circulation rate of the bed material. This allows higher combustion temperatures and thus enables the temperature to be maintained low in the pyrolysis chamber. Another advantage is that excessive cracking of the polymer is prevented or minimized, which increases the yield of the monomer product. Increasing the circulation rate can also prevent or minimize side reactions. The circulation rate of the bed material can be from 10 to 100 kg of bed material per kg of feedstock, more preferably from 20 to 60 kg of bed material per kg of feedstock.

[0021] The temperature difference between the combustion chamber and the pyrolysis chamber can be reduced by increasing the circulation rate of the bed material. This enables higher temperatures to be reached in the pyrolysis chamber. The circulation rate of the bed material can be in the range of 10 to 100 kg of bed material per kg of feedstock, more preferably 20 to 60 kg of bed material per kg of feedstock.

[0022] In addition, providing heat directly via the hot bed material results in the feedstock being exposed to substantially uniform temperatures in the pyrolysis chamber, since all or substantially all of the heat for the pyrolysis process is provided by the bed material. In contrast, conventional heating techniques that provide heat indirectly through the walls of the pyrolysis reactor vessel or via internal heat pipes result in temperature hot spots and high surface temperatures. These temperature hot spots and high surface temperatures result in excessive cracking of the feedstock. For example, the temperature at or near the chamber wall of a conventional naphtha cracker can easily be 200°C higher than the temperature required for cracking of naphtha and naphtha gas. Therefore, providing heat via the bed material prevents or minimizes side reactions, and thus increases the yield of high-value chemicals.

[0023] The bed material is preferably sand, such as crystalline quartz sand. Alternatively, the bed material may be olivine or dolomite. Olivine and dolomite may exhibit catalytic activity. The hot bed material may also contain additional components. Clay materials may be added to the bed material to avoid agglomeration of particles. Typically, high porosity clay minerals are used, such as halloysite, kaolinite, sepiolite or a combination thereof.

[0024] The pyrolysis process can be performed at a temperature ranging from 700° C. to 800° C., preferably at a temperature ranging from 730° C. to 770° C. Performing the pyrolysis process between 730° C. to 770° C. provides a large amount of olefins and reduces the amount of heavy hydrocarbon fractions (such as heavy tar fractions). The pyrolysis process temperature is also selected according to the type of feed used (i.e., the temperature of polymer depolymerization).

[0025] In the combustion chamber, the combustion process is carried out at a higher temperature than the pyrolysis process. In the combustion chamber, the combustion process may be performed at a temperature in the range of 30°C to 130°C higher than the pyrolysis process, preferably at a temperature in the range of 50°C to 110°C higher than the pyrolysis process. For example, the pyrolysis process is performed at a temperature in the range of 650°C to 800°C, and the combustion process is performed at a temperature in the range of 30°C to 130°C higher than the pyrolysis process. By further example, the pyrolysis process is performed at a temperature in the range of 730°C to 770°C and the combustion process is performed at a temperature in the range of 50°C to 110°C higher than the pyrolysis process.

[0026] The method may further comprise (c) transferring the product gas to a product recovery unit and separating high value chemicals. Preferably, the method further comprises transferring the product gas from the pyrolysis chamber to a tar removal system to remove one or more tar fractions from the product gas before the product gas is subjected to step (c).

[0027] The tar removal system may include an absorption unit to remove light hydrocarbon fractions, such as light tar fractions, from the product gas. A portion of the light hydrocarbon / tar fraction may be transferred to a combustion chamber. The tar removal system may include a quench unit to remove heavy hydrocarbon / tar fractions, such as heavy tar fractions, from the product gas.

[0028] The product gas is preferably quenched via a quenching medium, typically oil, at a temperature in the range of from 50° C. to 95° C., preferably 60° C. to 90° C., more preferably 60° C. to 85° C. In one embodiment, the quenching is carried out at this temperature and at a pressure in the range of 0.8-2.0 bar, preferably in the range of 1.0-1.5 bar.

[0029] In a preferred embodiment, the product gas is quenched via a quench medium (typically oil) at a temperature in the range of from 50°C to 95°C (at atmospheric pressure, i.e. 1 bar), preferably 60°C to 90°C (at atmospheric pressure, i.e. 1 bar), more preferably 60°C to 85°C (at atmospheric pressure, i.e. 1 bar). In an alternative embodiment, the product gas is quenched via a quench medium (typically oil) at a temperature in the range of from 55°C to 95°C (at 1.3 bar), preferably 65°C to 85°C (at 1.3 bar).

[0030] The quench medium typically cools the product gas to a water dew point temperature, which is typically in the range of from 50°C to 95°C, preferably 60°C to 90°C, more preferably 60°C to 85°C. As the skilled person will appreciate, the water dew point temperature may vary depending on the pressure. Preferably, the pressure in this context is in the range of 0.8-2.0 bar, more preferably in the range of 1.0-1.5 bar. In a preferred embodiment, the quench medium is used to cool the product gas to a water dew point temperature of from 50°C to 95°C (at atmospheric pressure), preferably 60°C to 90°C (at atmospheric pressure, i.e. 1 bar), more preferably 60°C to 85°C (at atmospheric pressure, i.e. 1 bar). In an alternative embodiment, the quench medium is used to cool the product gas to a water dew point temperature of from 55°C to 95°C (at 1.3 bar), preferably 65°C to 85°C (at 1.3 bar).

[0031] Quenching is performed by contacting the product gas with a quench medium, during which compounds may be removed from the product gas and dissolved in the quench medium, which may result in an increase in the viscosity of the quench medium. The quench medium after quenching may also be referred to as spent quench medium.

[0032] The spent quench medium obtained after quenching may have a viscosity in the range of from 40 to 200 cP, preferably from 80 to 160 cP. Such a viscosity is ideal for reusing the quench medium, since any compounds dissolved therein during quenching are easily removed from the spent quench medium.

[0033] The skilled person will be able to determine a suitable way to measure viscosity on-line or off-line. In the context of the present invention, viscosity measurements are determined off-line (measured in centipoise (cP)) using samples over a temperature range of from 50°C to 95°C via torque measurements on a Brookfield Ametek rheometer analyser. Typically, viscosity is measured at the temperature and pressure at which quenching is performed.

[0034] A portion of the heavy hydrocarbon / tar fraction can be transferred to the combustion chamber, thereby using the heavy hydrocarbon / tar fraction as the main energy source in the pyrolysis process. This advantageously prevents or limits the need to rely on external energy sources (such as natural gas). Preferably, the tar removal system includes an absorption unit and a quench unit. The quench unit can also be used to remove particles. Another advantage of performing the pyrolysis reaction at a temperature of from 700° C. to 800° C. is that a sufficient amount of heavy tar is produced to maintain an appropriate oil viscosity.

[0035] Class 1 to 5 tars are defined by the number of aromatic rings present in the tar, with Class 1 tars consisting of compounds with one aromatic ring, Class 2 tars consisting of compounds with two aromatic rings, Class 3 tars consisting of compounds with three aromatic rings, Class 4 tars consisting of compounds with four aromatic rings, and Class 5 tars consisting of compounds with five or more aromatic rings. For example, naphthalene and fluorene are both Class 2 tars because they contain two aromatic rings (benzene rings).

[0036] Class 1 and Class 2 tars are typically considered light tars, while Class 4 and Class 5 tars are typically considered heavy tars. Class 3 tars can be considered either light or heavy tars. Light Class 3 tar fractions are tar fractions that are non-condensable in a tar removal system, and heavy Class 3 tar fractions are condensable tar fractions in a tar removal system.

[0037] Class 1 (i.e. benzene to cresols) has a viscosity of 0-30 cP; Class 2 (i.e. naphthalene to fluorene) has a viscosity of 10-20 cP; Class 3 (i.e. phenanthrene to pyrene) has a viscosity of 30-90 cP; Class 4 (i.e. benzanthracene to benzofluoranthene) has a viscosity of 75-285 cP; Class 5 (i.e. benzopyrene and coronene) has a viscosity of 285-715 cP. Carrying out the pyrolysis reaction at a temperature of from 700°C to 800°C ensures that sufficient amounts of Class 3 to 5 tars are collected to provide a suitable tar:dust ratio. Preferably, more Class 3-4 tars are collected than Class 5 tars so that the viscosity is not too high. The term light hydrocarbons / tars can be considered to include methane and olefins and / or tars defined in Class 1, Class 2 and Class 3 (light tars of Class 3). The term heavy hydrocarbons / tars may be considered to include tars defined in Class 3 (heavy tars of Class 3), Class 4 and Class 5.

[0038] Heavy tars are typically those that condense when the product gas is cooled from the temperature at which the pyrolysis process is carried out to a temperature of the product gas on the order of the water dew point. This typically occurs during the tar removal step. Light tars remain gaseous under such conditions.

[0039] Preferably, the method further comprises transferring the product gas from the pyrolysis chamber to a tar removal system to remove one or more tar fractions from the product gas. Here, heavy tar is typically removed from the product gas.

[0040] The product gas transferred to the tar removal system preferably contains Class 3-5 heavy tar fractions, and the content of Class 3-4 heavy tar fractions is greater than the content of Class 5 heavy tar fractions based on the weight of the total Class 3-5 heavy tar fractions.

[0041] The product gas transferred to the tar removal system preferably contains, by weight of the total Class 3-5 heavy tar fraction: (i) from 50% to 80% Class 3 heavy tar, (ii) from 10% to 40% Class 4 heavy tar, and (iii) 10% or less Class 5 heavy tar. Or in other words, the product gas transferred to the tar removal system preferably contains, by weight of the total Class 3-5 heavy tar fraction, from 50% to 80% Class 3 heavy tar, by weight of the total Class 3-5 heavy tar fraction, from 10% to 40% Class 4 heavy tar, and 10% or less Class 5 heavy tar, by weight of the total Class 3-5 heavy tar fraction.

[0042] The product gas transferred to the tar removal system preferably contains from 20 to 30 g / Nm 3 Class 3-5 heavy tar.

[0043] The ratio of dust to Class 3-5 heavy tars of the product gas transferred to the tar removal system is preferably from 1:99 to 10:90.

[0044] The product gas transferred to the tar removal system preferably contains from 0 to 2 g / Nm 3 of dust.

[0045] The gas may also be transferred to a particulate removal unit (such as a cyclone separator) before being transferred to the tar removal system. The tar removal system may include an absorption unit to remove light hydrocarbon / tar fractions, such as light tar fractions, from the product gas. Preferably, the tar removal system may include an absorption unit to remove light hydrocarbon / tar fractions, such as light tar fractions, and dust from the product gas.

[0046] The absorption unit preferably comprises an absorption tower and a stripping tower that are communicated with each other to allow the detergent to flow continuously between these towers. Washing can be carried out by co-current mode or countercurrent mode to remove impurities, such as tar from the gas. The detergent can be a mineral oil or a synthetic oil. For example, paraffin oil or an organic aryl polysiloxane oil, preferably an organic aryl polysiloxane oil.

[0047] The stripping agent used in the stripping tower can be hot air, steam, nitrogen, carbon dioxide, boiler flue gas or a mixture thereof, preferably hot air. The flow rate of the hot air entering the stripping tower can be from 50% to 200%, preferably 100% to 200% of the product gas stream. In the case of using air, these flow rates have the advantage of reducing the risk of running above the maximum allowable level of tar when the internal explosion limit of the stripper gas. The stripping agent can be the combustion air for the combustion chamber. The stripping tower and the stripping agent enable the scrubbing agent to be reused in the absorption tower.

[0048] The quench unit preferably comprises a quench tower adapted to receive the product gas from the pyrolysis chamber. Optionally, the quench unit may comprise a wet electrostatic precipitator connected to the quench tower. The wet electrostatic precipitator is adapted to remove aerosols from the product gas.

[0049] Fluidizing gas can be transferred to the conveying zone to control the circulation rate of the bed material. Fluidizing gas can be transferred to more than one area in the conveying zone. Preferably, the temperature difference between the combustion chamber and the pyrolysis chamber is increased or decreased by changing the ratio of fluidizing gas transferred to the first area of ​​the conveying zone relative to the fluidizing gas transferred to the second area of ​​the conveying zone. In a preferred embodiment, the conveying zone includes a first area that allows the bed material to flow downward from the combustion chamber and a second area that allows the bed material to flow upward to the pyrolysis chamber. Fluidizing gas can be transferred to the upstream portion of the second area and the downstream portion of the second area. The terms upstream portion and downstream portion are considered to indicate the direction in which the bed material flows through the fluidized reactor system. In other words, the bed material is circulated from the first area to the upstream portion and then circulated to the downstream portion before being transferred to the pyrolysis chamber. Fluidizing gas can be transferred to the pyrolysis chamber to control the circulation rate of the bed material. The circulation rate of the bed material can be increased or decreased by changing the amount of fluidizing gas transferred to the conveying zone and / or the pyrolysis chamber. The advantages associated with increasing and decreasing the circulation rate of the bed material are discussed above. The circulation rate of the bed material can be increased or decreased by changing the amount of fluidizing gas diverted to more than one zone of the transport zone. Thus, changing the amount of fluidizing gas can reduce or increase the temperature difference between the combustion chamber and the pyrolysis chamber by increasing or decreasing the circulation rate of the bed material, as described above. Preferably, the fluidizing gas is diverted only to the second zone of the transport zone, or in other words, no fluidizing gas is diverted to the first zone of the transport zone.

[0050] In a preferred embodiment, the circulation rate of the bed material is reduced by adding more fluidizing gas to the downstream portion of the second zone than to the upstream portion of the second zone. Here, the ratio of fluidizing gas added to the upstream portion relative to the fluidizing gas added to the downstream portion is 1:1-6, typically 1:1.5-4. The circulation rate of the bed material is increased by adding less fluidizing gas to the downstream portion of the second zone than to the upstream portion of the second zone. Here, the ratio of fluidizing gas added to the upstream portion relative to the fluidizing gas added to the downstream portion is 1-6:1, typically 1.5-4:1. Redistributing the fluidizing gas so that more fluidizing gas is provided in the upstream portion than in the downstream portion increases the flow rate of the hot bed material and thereby reduces the temperature difference from the combustion chamber to the pyrolysis chamber. Therefore, the redistribution of the fluidizing gas increases the yield of high-value chemicals and reduces or prevents by-products.

[0051] In another preferred embodiment, the circulation rate of the bed material is reduced by adding more fluidizing gas to the downstream portion of the second zone and / or the pyrolysis chamber than to the upstream portion of the second zone. Here, the ratio of fluidizing gas added to the upstream portion and / or the pyrolysis chamber relative to the fluidizing gas added to the downstream portion is 1:1-6, typically 1:1.5-4. The circulation rate of the bed material is increased by adding less fluidizing gas to the downstream portion of the second zone and / or the pyrolysis chamber than to the upstream portion of the second zone. Here, the ratio of fluidizing gas added to the upstream portion relative to the fluidizing gas added to the downstream portion 35 and / or the pyrolysis chamber is 1-6:1, typically 1.5-4:1.

[0052] Fluidizing gas can also be transferred to the first zone. This helps to circulate the bed material to the pyrolysis chamber. Another advantage is that it prevents or reduces the flow of flue gas into the pyrolysis chamber. This is important because flue gas contains pollutants such as O 2 and NO x .

[0053] Thus, the fluidized reactor system allows different amounts of fluidizing gas to be added to the transport zone and / or pyrolysis chamber and thereby control the transfer rate during operation.Another advantage of providing more than one zone to add fluidizing gas is to prevent one zone from becoming blocked or partially blocked.

[0054] Thus, the fluidized reactor system allows different amounts of fluidizing gas to be added to the transport zone and / or the pyrolysis chamber and thereby control the transfer rate during operation. Another advantage of providing fluidizing gas to more than one zone is that in the event that one zone becomes blocked or partially blocked, the resulting reduction in bed material transport can be overcome without having to change or clean the reactor.

[0055] The fluidizing gas may be transferred from a stripper and / or an external source. Preferably, the fluidizing gas to the pyrolysis chamber comes from an external source and the fluidizing gas to the combustion chamber comes from the stripper. Preferably, the fluidizing gas delivered to the delivery chamber and / or the pyrolysis chamber is steam. These flow rates have the advantage of reducing secondary polymerization of olefins and avoiding or limiting the formation of soot and / or high molecular weight hydrocarbons / tar.

[0056] The velocity of the fluidizing gas in the second region of the transport zone may be from 0.5 to 3 m / s, preferably from 1 to 2.5 m / s, even more preferably 2 m / s. The velocity of the fluidizing gas in the upstream part and / or downstream part of the second region of the transport zone may be from 0.5 to 3 m / s, preferably from 1 to 2.5 m / s, even more preferably 2 m / s. This velocity range allows moving the bed material by actually fluidizing it.

[0057] The velocity of the fluidizing gas in the pyrolysis chamber may be from 5 to 8.5 m / s, preferably from 5.5 to 7.5 m / s. These velocity ranges allow the bed material to be transported through the pyrolysis chamber. Another advantage of these velocity ranges is that they enable the bed material to be blown out of the pyrolysis chamber and circulated into the combustion chamber.

[0058] The velocity of the fluidizing gas depends on the density of the fluidizing gas and the particle size of the bed material. Generally, the particle size has a greater influence on the required viscosity of the fluidizing gas.

[0059] The bed material may have a dp50 of from 240 to 280 μm, preferably 260 μm.The average particle size is determined using laser diffraction particle size analysis, for example using a Malvern Mastersizer.

[0060] The density of the fluidizing gas in the conveying zone may be from 0.9 to 1.1 kg / Nm 3 , preferably 1.0kg / Nm 3 The density of the fluidizing gas in the upstream part and / or downstream part of the second region of the conveying zone may be from 0.9 to 1.1 kg / Nm 3 , preferably 1.0kg / Nm 3 The density of the fluidized bed material in the conveying zone may be from 900 to 1100 kg / m 3 , preferably 1000kg / m 3 The density of the fluidized bed material in the upstream part and / or downstream part of the second region of the conveying zone may be from 900 to 1100 kg / m 3 , preferably 1000kg / m 3 .

[0061] In an embodiment, the velocity of the fluidizing gas in the upstream part and / or downstream part of the second region of the conveying zone may be from 0.5 to 3 m / s, preferably from 1 to 2.5 m / s, even more preferably 2 m / s; the bed material has a dp50 of from 240 to 280 μm, preferably 260 μm; and the density of the fluidizing gas in the upstream part and / or downstream part of the second region of the conveying zone may be from 0.9 to 1.1 kg / Nm 3 , preferably 1.0kg / Nm 3 .

[0062] The velocity of the bed material in the first zone may be from 0.05 to 0.15 m / s, preferably 0.1 m / s. The density of the bed material may be from 1440 to 1760 kg / m 3 , preferably 1600kg / m 3 .

[0063] In the upper part (downstream part) and / or the lower part (upstream part) of the pyrolysis chamber, the velocity of the fluidizing gas may be from 5 to 8.5 m / s, preferably from 5.5 to 7.5 m / s. The density of the fluidized bed material in the upper part and / or the lower part of the pyrolysis chamber may be from 90 to 110 kg / m 3 , preferably 100kg / m 3 The density of the fluidizing gas in the upper and / or lower part of the pyrolysis chamber may be from 0.9 to 1.1 kg / Nm 3 , preferably 1.0kg / Nm 3 .

[0064] When an unused gas or energy source is used or transferred to a fluidized reactor system as part of the fluidizing agent, such as when transferring the fluidizing agent from a product recovery unit to a combustor, the fluidizing gas may be appropriately referred to as a non-condensable gas, combustion air, or energy source. The energy source may be a gas, liquid, or solid. Non-condensable gases may include CO, H 2 , CH 4 , N 2 , C 2 and / or C 3 The non-condensable gas may be a fuel gas. The energy source may include fossil fuels, solid biomass, waste feedstock, hydrocarbon condensates from a product recovery unit, or a combination thereof. Preferably, the fluidizing gas is a gas or steam generated by the product gas of the pyrolysis process. More preferably, the fluidizing gas is steam. Even more preferably, the fluidizing gas for the delivery zone is steam. When the fluidizing gas is generated by the product gas, the following steps may be applied: the product gas generated in the pyrolysis chamber may be transferred to the product recovery unit, and the separated fluidizing gas may be recycled back to the pyrolysis chamber and / or transferred to the delivery zone. Preferably, the fluidizing gas for the combustion chamber is air. The advantage of transferring the fluidizing gas to the combustion chamber is that the fluidizing gas can serve as an energy source.

[0065] The method may further comprise separating tail gas or waste gas from the product gas. Preferably, the tail gas or waste gas is obtained after cryogenic treatment. The method may also comprise transferring at least a portion of the tail gas or waste gas to a combustion chamber. Advantageously, the tail gas or waste gas can be used as an energy source for the combustion chamber. The tail gas or waste gas can also be used to replace tar as an energy source for the combustion chamber, so that chemicals can be separated from the tar, or alternatively so that the tar can be used as a source for carbon black production. The term tail gas or waste gas can be taken to mean non-condensable gases. The tail gas or waste gas typically contains CO, H 2 , CH 4 and CO between 10%-20% 2 .CO、H 2 , CH 4 Typical amounts are provided in Table 1.

[0066] At least a portion of the tail gas or waste gas can be used to produce chemicals, preferably hydrogen, CO and / or olefins. For example, hydrogen can be recovered from the tail gas or waste gas by using a membrane. The tail gas or waste gas can also be catalytically converted into fuels such as synthetic natural gas or methanol, the latter providing the option of further increasing the olefin yield by applying a methanol to olefin (MtO) synthesis process.

[0067] The advantage of transferring a portion of the light tar fraction to the free space of the combustion chamber is that the operating temperature of the combustion chamber and the pyrolysis chamber is reduced. Non-condensable gases, combustion air or energy sources may also include steam or moisture. Non-condensable gases, combustion air or energy sources may contain 5% to 10% steam or moisture by weight of non-condensable gases, combustion air or energy sources. This amount of steam or moisture is required for stripping a sufficient amount of tar fraction from the scrubber in the stripping tower. Another advantage of transferring non-condensable gases, combustion air or energy sources containing 5% to 10% steam or moisture by weight of non-condensable gases, combustion air or energy sources to the combustion chamber is that the operating temperature of the pyrolysis chamber is reduced.

[0068] The fluidizing gas conveyed to the combustion chamber for fluidizing purposes may be combustion air, for example directed via an absorption unit or more particularly from a stripping column. Alternatively or in addition, the fluidizing gas may be transferred to the combustion chamber from a product recovery unit and / or an external source.

[0069] The feedstock may contain from 5% to 30%, preferably from 5% to 15%, even more preferably from 5% to 10% water originating from the waste and / or added separately to the feedstock. If the waste contains insufficient water, water may be added separately to the feedstock to reach a water content of 5% to 30%.

[0070] Preferably, waste water from the product recovery unit is transferred to the combustion chamber. The amount of water used may depend on the amount of plastic in the feedstock. A related advantage of providing a feedstock with a water content as described is that the operating temperature of the screw feeder is maintained at a suitable level to avoid decomposition of the waste material within the screw feeder.

[0071] Preferably, the method further comprises transferring a fraction resulting from the pyrolysis process to a combustion chamber and performing a combustion process in a bed material to provide a flue gas. The fraction may comprise unconverted char.

[0072] The method may further include diverting the flue gas to a heat recovery system.

[0073] The fluidized reactor system may further include a downcomer to allow the bed material to circulate from the pyrolysis chamber to the combustion chamber. The downcomer may be coaxially positioned around the pyrolysis chamber. In use, the bed material flows through the upper portion of the pyrolysis chamber into the downcomer and then circulates to the combustion chamber. Therefore, the bed material layer always surrounds the pyrolysis chamber and acts as a thermal insulation layer between the wall of the pyrolysis chamber and the downcomer. This reduces the radial transfer of heat from the combustion chamber to the pyrolysis chamber, and thereby prevents the walls of the pyrolysis chamber from being heated to high temperatures, which may cause further cracking.

[0074] Fluidizing gas can also be added to the downcomer. This helps prevent product gas from flowing into the combustion chamber via the bed material and thereby increases the yield of product gas.

[0075] The fluidizing gas and / or non-condensable gas / energy source velocity is controlled by flow transducers within the fluidized reactor system.

[0076] The combustion chamber may be arranged to surround at least a portion of the pyrolysis chamber. The pyrolysis chamber may be arranged centrally or substantially centrally within the combustion chamber.

[0077] The method may further include transferring the product gas from the pyrolysis chamber to a particulate removal unit (e.g., including a cyclone separator) before transferring the product gas to a product recovery unit or a tar removal system. Preferably, the method further includes transferring the product gas from the pyrolysis chamber to a particulate removal unit (e.g., a cyclone separator) to remove dust from the product gas before transferring the product gas to the tar removal system.

[0078] In an embodiment, the present invention relates to the use of a fluidized reactor system for depolymerizing a polymer into one or more monomers, the fluidized reactor system comprising a pyrolysis chamber, a combustion chamber, and a bed material circulating from the combustion chamber to the pyrolysis chamber via a transport zone.

[0079] The pyrolysis process may be performed in the bed material at a temperature ranging from 400° C. to 750° C. to obtain a polymer product gas comprising depolymerization of the monomers.

[0080] The temperature difference between the combustion chamber and the pyrolysis chamber can be adjusted by varying the ratio of fluidizing gas diverted to the first region of the transport zone relative to the fluidizing gas diverted to the second region of the transport zone.

[0081] The temperature difference between the combustion chamber and the pyrolysis chamber can be increased or decreased by changing the circulation rate of the bed material. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 A schematic diagram of a reactor system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0083] exist Figure 1In the embodiment shown in the schematic diagram of , a fluidized reactor system for producing high-value chemicals from a feedstock is provided, wherein the feedstock is or contains waste. The waste is biomass, biomass-rich refuse-derived fuel, plastic-rich refuse-derived fuel and plastic, or a combination thereof. The reactor system includes a pyrolysis chamber 2, which includes a feedstock input 4 (which may include a feedstock bin), a first fluidizing gas input 6, a second fluidizing gas input 8 and a product gas output 10. A combustion chamber 12 defined by a wall 14 at least partially surrounds the pyrolysis chamber 2 and is connected to a flue gas output 16, a first combustion air input 20 and a second combustion air gas input 18. The combustion chamber 12 is also connected to a water input 22, which is preferably wastewater from a product recovery unit 24. The product recovery unit 24 includes a tail gas output 26 and one or more product outputs, such as C 2 Exit 28, C 3 Exit 30 and C 4outlet 32. The combustion chamber 12 comprises a fluidized bed zone 34, an air chamber 36 located below the fluidized bed zone 34, and a free space 38 located above the fluidized bed zone 34. A downcomer 40 is also provided to allow a fraction of bed material, char and product gas (typically 1% to 2% by weight of the total weight of product gas) to be transferred from the pyrolysis chamber 2 to the combustion chamber 12. The pyrolysis chamber 2 and the combustion chamber 12 are connected via a conveying zone 42. The conveying zone 42 comprises a first region 44 to allow the bed material to flow downward from the combustion chamber 12, and a second region 46 to allow the bed material to flow upward to the pyrolysis chamber 2. The second region 46 comprises a downstream portion 47 and an upstream portion 48. The first region 44 is connected to a third fluidizing gas input 50 for providing fluidizing gas to the pyrolysis chamber 2 via the conveying zone 42. The pyrolysis chamber 2 is connected to the first fluidizing gas input 6 via the conveying zone 42. Or in other words, the first fluidizing gas input 6 is connected to the upstream portion 48 of the second zone 46 to allow the fluidizing fluid to flow into the second zone 46, thereby transferring the fluidizing liquid to the pyrolysis chamber 2. The pyrolysis chamber 2 can be connected to the second fluidizing gas input 8 via the delivery zone 42. Or in other words, the second fluidizing gas input 8 is connected to the downstream portion 47 of the second zone 46 to allow the fluidizing fluid to flow into the second zone 46, thereby transferring the fluidizing liquid to the pyrolysis chamber 2. Alternatively, the second fluidizing gas input 8 is directly connected to the pyrolysis chamber 2 to allow the fluidizing fluid to flow directly into the pyrolysis chamber 2. The second zone 46 can be a part of the pyrolysis chamber 2. The delivery zone 42 is used to circulate the bed material between the combustion chamber 12 and the pyrolysis chamber 2. The product gas output 10 can be directly connected to the tar removal system 52 (which can include a quench unit 54 and / or an absorption unit 56). Alternatively, the product gas output 10 can be connected to a particulate removal unit 58 (such as a cyclone separator). The particulate removal unit 58 includes a product gas output 60 connected to the tar removal system 52. The product gas output 10 may be connected to a cooler 62, which in turn is connected to a particulate removal unit 58. The particulate removal unit 58 further includes an ash gas outlet 64 for transferring ash to the fluidized bed region 34 of the combustion chamber 12. Preferably, the quench unit 54 includes a quench tower 66 adapted to receive product gas from the pyrolysis chamber 2. The quench tower 66 includes an ash and tar output 68 and a quenched product gas output 70. The product gas output 70 is connected to a wet electrostatic precipitator 72. The wet electrostatic precipitator 72 includes an aerosol liquid output 74, which is connected to an oil circulation loop (not shown) of the quench tower 66, wherein the oil circulation loop is connected to the combustion chamber 12. The wet electrostatic precipitator 72 further includes a deaerosolized product gas output 76 connected to the absorption unit 56. The absorption unit 56 includes an absorption tower 78 connected to the deaerosolized product gas output 76 and a stripping tower 80 in communication with the absorption tower 78. Absorber 78 includes a product gas output 82 that is connected to product recovery unit 24 .The stripping tower 80 includes a stripping section 84 and a degassing section 86. The stripping section 84 is connected to the free space 38 via the first combustion air input 20 and is connected to the combustion bed via the combustion air input 20. The degassing section 86 includes a degassing agent input 90 for degassing the scrubbing agent. Preferably, the stripping section 84 uses air and the degassing section 86 uses steam. Alternatively, the stripping tower 80 may include only a stripping section that uses steam. When only a stripping section is present, the combustion air is provided to the combustion chamber via a separate source rather than through the stripping tower 80.

[0084] The combustion air inputs 18 and 20 are arranged for supplying a further source of combustible gas (i.e., tar from the stripper 80) to the combustion chamber 34 to heat the bed material and free space 38 of the combustion chamber 12. The combustion gas diverted via the combustion air input 20 also serves as a fluidizing gas for the bed material. The flue gas output 16 of the combustion chamber 12 may be connected to a gas cooler 92, which in turn is connected to a gas filter 94 for removing fly ash. The gas filter 94 includes a cleaned flue gas output 98 and a fly ash output 96. The first region 44 of the transport zone 42 may include a steam input 100 for stripping the flue gas, in particular O, from the circulating bed material. 2 and NO x , and thereby remove these contaminants before the product gas enters the product recovery unit 24.

[0085] In use, bed material (preferably sand, such as crystalline quartz sand or alternatively olivine or dolomite) is continuously circulated between the pyrolysis chamber 2 and the combustion chamber 12 via the downcomer 40 and the conveying zone 42. The feedstock is introduced into the pyrolysis chamber 2 via the feedstock input 4, and the pyrolysis process is carried out in the bed material at a temperature ranging from 650° C. to 850° C. to obtain a product gas and a side drawdown containing high-value chemicals. The side drawdown is transferred from the pyrolysis chamber 2 to the combustion chamber 12 (via the settling chamber 102 and the downcomer 40) through the bed material and is burned in the fluidized bed zone 34 in the presence of air at a temperature from 30° C. to 130° C. higher than the pyrolysis process to provide a flue gas for heating the bed material in the combustion chamber 12. The flue gas then leaves the combustion chamber 12 via the free space 38. The flue gas mainly contains N 2 , CO 2 and H 2 O. Flue gas may also contain the following pollutants: CO, NO x 、SO xand HCl. The bed material retains the heat of the combustion process, and this heat is used in the pyrolysis process when the bed material is circulated from the combustion chamber 12 to the pyrolysis chamber 2 via the conveying zone 42. Pyrolysis of the feedstock in the pyrolysis chamber 2 using the heat derived from the combustion process results in a temperature difference between the combustion chamber 12 and the pyrolysis chamber 2. Increasing the circulation rate of the bed material reduces the temperature difference between the combustion chamber 12 and the pyrolysis chamber 2, and thereby enables a lower temperature to be reached in the pyrolysis chamber 2. However, the higher temperature reached is below the temperature at which excessive cracking occurs. Reducing the circulation rate of the bed material increases the temperature difference between the combustion chamber 12 and the pyrolysis chamber 2, and thereby allows a higher combustion temperature while maintaining a low temperature in the pyrolysis chamber 2.

[0086] The first fluidizing gas input 6, the second fluidizing gas input 8 and the third fluidizing gas input 50 and the combustion air inputs 18 and 20 can be advantageously used in combination with each other or separately from each other. The first fluidizing gas input 6, the second fluidizing gas input 8 and the third fluidizing gas input 50 and the combustion air inputs 18 and 20 are used to control the temperature in the pyrolysis chamber 2 and the combustion chamber 12. The fluidizing gas (preferably steam) from the first fluidizing gas input 6, the second fluidizing gas input 8 and the third fluidizing gas input 50 is used to control the flow rate of the bed material through the conveying zone 42. In particular, the velocity of the fluidizing gas in the second region 46 of the conveying zone 42 can be from 0.5 to 3 m / s, preferably from 0.5 to 2 m / s. The velocity of the fluidizing gas in the pyrolysis chamber 2 can be from 5 to 8.5 m / s, preferably from 5.5 to 7.5 m / s.

[0087] The first fluidizing gas input 6 transfers fluidizing gas to the upstream portion 48 of the second zone 46 of the conveying zone 42. The second fluidizing gas input 8 transfers fluidizing gas to the downstream portion 47 of the second zone 46 of the conveying zone 42. The third fluidizing gas input 50 transfers fluidizing gas to the first zone 44 of the conveying zone 42. The fluidizing gas input 20 transfers fluidizing gas to the air chamber 36 of the combustion chamber 12. The bed material flows from the first zone 44 to the second zone 46. In the first zone 44, the fluidizing gas flows downwardly out of the combustion chamber 12. In the second zone 46, the fluidizing gas flows upwardly from the combustion chamber 12 and enters the pyrolysis chamber 2. The fluidizing gas can be transferred to the pyrolysis chamber 2 to control the circulation rate of the bed material. The circulation rate of the bed material can be increased or decreased by changing the amount of fluidizing gas transferred to the conveying zone 42 and / or the pyrolysis chamber 2.

[0088] The circulation rate of the bed material is reduced by adding more fluidizing gas to the downstream portion 47 of the second zone 46 than to the upstream portion 48 of the second zone 46. Here, the ratio of the fluidizing gas added to the upstream portion 48 relative to the fluidizing gas added to the downstream portion 47 is 1:1-6, typically 1:1.5-4. The circulation rate of the bed material is increased by adding less fluidizing gas to the downstream portion 47 of the second zone 46 than to the upstream portion 48 of the second zone 46. Here, the ratio of the fluidizing gas added to the upstream portion 48 relative to the fluidizing gas added to the downstream portion 47 is 1-6:1, typically 1.5-4:1. Alternatively, the circulation rate of the bed material is reduced by adding more fluidizing gas to the downstream portion 47 of the second zone 46 and / or the pyrolysis chamber 2 than to the fluidizing gas added to the upstream portion 48 of the second zone 46. Here, the ratio of fluidizing gas added to the upstream portion 48 relative to the fluidizing gas added to the downstream portion 47 and / or the pyrolysis chamber 2 is 1:1-6, typically 1:1.5-4. The circulation rate of the bed material is increased by adding less fluidizing gas to the downstream portion 47 of the second zone 46 and / or the pyrolysis chamber 2 than to the upstream portion 48 of the second zone 46. Here, the ratio of fluidizing gas added to the upstream portion 48 relative to the fluidizing gas added to the downstream portion 47 and / or the pyrolysis chamber is 1-6:1, typically 1.5-4:1. The fluidizing gas can also be transferred to the first zone 44. Therefore, the fluidized reactor system allows different amounts of fluidizing gas to be added to the conveying zone 42 and / or the pyrolysis chamber 2, and thereby control the transfer rate during operation. The advantage of using fluidizing gas to increase the flow rate of the hot bed material is that the temperature difference between the combustion chamber 12 and the pyrolysis chamber 2 is reduced. The reduction in temperature difference prevents or minimizes side reactions and thereby increases the yield of high-value chemicals.

[0089] The flow rate of the fluidizing gas may be the same for each of the first fluidizing gas input 6, the second fluidizing gas input 8, and the third fluidizing gas input 50. Alternatively, the flow rate of the fluidizing gas may be different for one or more of the first fluidizing gas input 6, the second fluidizing gas input 8, and the third fluidizing gas input 50. Preferably, the fluidizing gas from the first fluidizing gas input 6, the second fluidizing gas input 8, and the third fluidizing gas input 50 is derived from an external source.

[0090] The product gas (e.g. at a temperature of 750°C) is preferably transferred from the pyrolysis chamber 2 to a gas cooler 62 via a product gas output 10. The product gas is then cooled (e.g. to a temperature of 500°C) before being transferred to a particulate removal unit 58 to remove solid particulates (bed material as well as carbonaceous ash) and subsequently to a quench tower 66. The solid particulates (e.g., ash) removed in the particulate removal unit 58 are sent to the combustion chamber 12 via an ash gas outlet 64. This is primarily to burn the char content of the ash, producing a carbon-free ash that is transferred out of the combustion chamber 12 via a flue gas output 16. This reduces or eliminates the need to dispose of carbonaceous ash, which has a high disposal cost. In addition, this reduces the need to handle pyrophoric carbonaceous ash. The product gas is quenched in the quench tower 66 using cycle oil at atmospheric pressure at a temperature of 50°C to 90°C, typically 60°C to 90°C, even more typically 60°C to 80°C, or at a higher temperature when a higher pressure is applied. This is commonly referred to as a "hot oil" quench. The oil is used to quench the gas to a temperature just above the water dew point. Temperatures below 50°C are not used because the oil becomes viscous and therefore more difficult to pump. The amount of oil used in the quench tower 66 is adjusted to avoid the temperature of the oil exceeding 200°C. The ash and tar separated from the quench tower 66 are sent to the combustion chamber 12 via the ash and tar output 68. The separated ash and tar provide an energy source in the combustion chamber 12, which provides heat for the pyrolysis process via the circulation of the bed material from the combustion chamber 12 to the pyrolysis chamber 2. This reduces or eliminates the need for external support fuel required for the pyrolysis process. The quenched product gas is then sent to a wet electrostatic precipitator 72 via the quenched product gas output 70 of the quench tower 66. The wet electrostatic precipitator 72 removes ash particles coated with oil in the product gas. This is by using a gas distribution system to spread the gas into a uniform flow distribution, and then applying a high voltage (40+kV) between the spray electrodes to charge the particles, and then collecting the charged particles at the collecting electrodes, where the particles agglomerate and are washed. The separated aerosol liquid containing the tar fraction is transferred to the combustion chamber 12 via the aerosol liquid output 74. The separated tar provides an energy source in the combustion chamber 12, which provides heat for the pyrolysis process via the circulation of the bed material from the combustion chamber 12 to the pyrolysis chamber 2. This reduces or eliminates the need for external support fuel required for the pyrolysis process. Then, the product gas of the deaerosol is transferred to the absorption tower 78 via the product gas output 76 of the deaerosol. Preferably, the product gas of the deaerosol is introduced at one end (i.e., the bottom) of the tower, and the detergent (e.g., oil) is introduced at the opposite end (i.e., the top) of the tower. The contact between the upwardly flowing gas and the downwardly flowing detergent can be enhanced by conventional means such as by spraying, using a packed column or a plate column. Scrubbing can be performed in co-current mode or counter-current mode to remove impurities, such as tar, from the gas.Absorption tower 78 can be operated, for example, at atmospheric pressure or slightly superatmospheric pressure at a temperature between 80° C. and 90° C., preferably 80° C., or at a higher temperature when a higher pressure is applied. When a higher pressure is applied, absorption tower 32 should be operated at a temperature of 220° C. or less, preferably 200° C. or less.

[0091] The purified product gas is then transferred from the absorber 78 to the product recovery unit 24 via the product gas output 82. The used scrubber is then circulated to the stripper 80 where the impurities / tars are desorbed from the scrubber via the stripping agent in the stripping section 84. The stripping agent (e.g., hot air, steam, nitrogen, carbon dioxide, flue gas, or a mixture thereof, preferably hot air) is introduced via the inlet 88. The combustion air transferred to the combustor 12 and used as a fluidizing gas may be transferred to the stripper unit 80 and then transferred back to the combustor 12.

[0092] The used scrubber is then circulated to the degassing section 86, where the scrubbing liquid is degassed by the degassing agent and then circulated out of the stripper 80 back into the absorber 78 to provide another round of scrubbing. Degassing the scrubber prevents air from entering the stripper and thereby preventing air from entering the product gas via the absorber. The degassing agent may be, for example, steam introduced into the degassing section 86 via an inlet 90. When the same pressure is used, the stripper 80 is operated at a temperature of about 100°C higher than the absorber 78, more typically between 70°C and 120°C higher than the absorber 78. At atmospheric pressure, the temperature may be between 150°C and 220°C. Instead of using a higher temperature, the stripper 80 may be operated at a lower pressure than the absorber 78. The air from the stripper 80 may be circulated to the combustion chamber 12 and used in the combustion process. The absorption / desorption process may be carried out via a temperature swing process or a pressure swing process. The temperature swing process can be used to strip light tars absorbed in oil at lower pressures (0.3 barg to 0.4 barg).The pressure swing process can be used to strip light tars absorbed in oil at higher pressures.

[0093] The gas ash removed by the particulate removal unit 58 may be transferred to the combustor 12. The product gas in the product recovery unit 24 is then sorted and separated into one or more product streams, which are then transferred out of the product recovery unit 24 using one or more outlets 28, 30, and 32. The hot flue gas from the combustor 12 (e.g., at a temperature of 850° C.) is transferred to a gas cooler 92 to cool the flue gas (e.g., to a temperature of 180° C.) and then transferred to a gas filter 94, which removes ash from the flue gas.

[0094] The feedstock input 4 may include a screw feeder. The screw feeder often exhibits a high operating temperature, which may cause some fractions of the feedstock in the screw feeder (such as polymers) to melt and subsequently block the screw feeder. The introduction of the feedstock at a sufficiently high rate via the fuel feed reduces the temperature of the screw feeder. Preferably, the fuel feed rate represented by the speed through the screw feeder is from 0.3m / s to 1.0m / s. The temperature of the screw feeder can also be reduced by passing the screw and its closed housing through an air chamber toward the pyrolysis zone, wherein the outside of the housing is cooled using 60°C to 80°C air. The temperature of the screw feeder can also be reduced by adding water and / or ash to the feedstock. Alternatively, if the feedstock is derived from biomass, for example, the feedstock can have enough water content, and therefore it is not necessary to add additional water to the feedstock. The feedstock can contain 5% to 30% water by weight of the feedstock, preferably containing 5% to 15%, more preferably 5% to 10% water by weight of the feedstock. The feedstock may also contain from 1% to 15% ash by weight of the feedstock, and pressure control valves may be used to ensure constant operating pressure between product recovery unit 24, quench unit 54 and absorption unit 56. This has the additional advantage of compensating for differential pressure variations across cooler 62.

[0095] Examples

[0096] Table 1 shows a list of high-value chemicals obtained via the claimed process when using wood, biogenic waste (composed of two-thirds biogenic material) and plastic waste (composed of two-thirds plastic material). In particular, the pyrolysis process is carried out at 750°C. Table 1 also shows high-value chemicals obtained by conventional naphtha cracking as a comparative example. These amounts are expressed as dry and N-free 2 / CO 2 Base report.

[0097] Table 1

[0098]

[0099]

[0100] Tests were conducted to determine the melting behavior of five types of pure plastics (polypropylene (PP), polyethylene (PE), polystyrene (PS), polycarbonate (PC) and polycarbonate acrylonitrile butadiene styrene (PC-ABS)) as well as electronic waste (eWaste). It was shown that these materials can begin to melt at temperatures between 140°C and 230°C without becoming a low-viscosity liquid (see Table 2). This behavior could potentially lead to plastic blockage inside screw feeders that are conventionally operated at high temperatures.

[0101] Table 2

[0102] stage PP PE PS PC PC-ABS eWaste Begin to transform 173℃ 134℃ 148℃ 215℃ 215℃ 173℃ Melting behavior 194℃ 139℃ 173℃ 231℃ 231℃ 215℃ Liquid Plastic 231℃ 194℃ 231℃ 281℃ nd nd

[0103] In contrast to Table 2, no feeding problems were observed for biomass, biogenic waste, or plastic waste. This is at least partially due to the ash and moisture content of these materials. Table 3 shows typical ash and moisture content for wood, biogenic waste, and plastic waste. Tests have shown that adding both ash and moisture to pure plastics results in fewer problems associated with feeding. In particular, moisture reduces the temperature of the raw material in the screw, and ash provides a protective coating on the sticky particles to reduce agglomeration of particles in the screw feeder.

[0104] Table 3

[0105]

[0106] Tables 4 and 5 show a list of high value chemicals obtained via alternative methods when using waste derived fuels. It was found that operating the pyrolysis process from 700°C to 800°C provided a large amount of high value chemicals in the product gas. These amounts are expressed as dry and N-free 2 / CO 2 Base report.

[0107] Table 4

[0108] Components (vol%) 749℃ 768℃ 796℃ 823℃ 863℃ <![CDATA[Hydrogen (H 2 )]]> 35.3 32.3 36.7 38.0 39.5 Carbon monoxide (CO) 27.9 32.7 32.7 31.3 33.5 <![CDATA[Methane (CH 4 )]]> 17.4 17.2 18.1 16.7 16.6 <![CDATA[Acetylene (C 2 H 2 )]]> 0.4 0.6 0.6 0.8 1.2 <![CDATA[Ethylene (C 2 H 4 )]]> 13.9 14.2 9.9 12.0 8.8 <![CDATA[Ethane (C 2 H 6 )]]> 1.7 1.2 0.8 0.6 0.3 <![CDATA[Propylene (C 3 H 6 )]]> 3.0 1.7 1.1 0.6 0.1 <![CDATA[Propane (C 3 H 8 )]]> 0.1 0.0 0.0 0.0 0.0 <![CDATA[Isobutene (iso-C 4 H 8 )]]> 0.2 0.1 0.1 0.0 0.0

[0109] Table 5

[0110] <![CDATA[Component (g / Nm 3 )]]> 749℃ 768℃ 796℃ 823℃ 863℃ <![CDATA[Benzene (C 6 H 6 )]]> 3.9 35.0 33.0 15.1 79.6 <![CDATA[Toluene (C 7 H 8 )]]> 5.2 18.2 7.0 12.1 6.3 <![CDATA[Styrene (C 8 H 8 )]]> 21.7 22.3 9.2 13.7 6.7 <![CDATA[Ethylbenzene (C 8 H 10 )]]> 0.7 0.4 nd 0.2 0.1 <![CDATA[m - Xylene (C 10 H 8 )]]> 0.9 1.0 0.3 0.4 0.1 <![CDATA[p - Xylene (C 10 H 8 )]]> 0.5 0.5 nd 0.2 nd

[0111] According to the process of the present invention, a pre-made mixture of 26wt.% biomass, 32wt.% polypropylene and 42wt.% polyethylene was tested and showed similar results. As seen in Table 6, the olefin yield is highest at about 750°C, where benzene, toluene and tar produced by overcracking increase at higher temperatures. The carbon yields for specific components (including the carbon yield for flue gas) are also shown in Table 6.

[0112] Table 6

[0113] Component (%) 701℃ 743℃ 792℃ Carbon monoxide (CO) 6.1 6.6 6.6 <![CDATA[Carbon dioxide (CO 2 )]]> 1.9 2.3 3.2 <![CDATA[Methane (CH 4 )]]> 8 11.3 13.7 <![CDATA[Acetylene (C 2 H 2 )]]> 0.2 0.3 0.6 <![CDATA[Ethylene (C 2 H 4 )]]> 16.5 21.3 20.1 <![CDATA[Ethane (C 2 H 6 )]]> 1.8 1.9 1.4 <![CDATA[Propylene (C 3 H 6 )]]> 10 8.9 3.2 <![CDATA[Propane (C 3 H 8 )]]> 0.4 0.3 0.1 <![CDATA[C 4 ]]> 5.7 5.2 2.2 <![CDATA[C 5 ]]> 0.5 0.4 0.2 <![CDATA[Benzene (C 6 H 6 )]]> 8.3 13.8 16 <![CDATA[Toluene (C 7 H 8 )]]> 3.3 3.7 3.1 tar 8 10 13.1 Flue gas 22.7 7.6 11.2

[0114] Surprisingly, it was found that operating the pyrolysis process between 700°C and 800°C improved the operability of the quench unit downstream of the pyrolysis chamber 1. Table 7 shows the tar distribution after cracking of biomass or refuse derived fuels at 750°C or 850°C based on Class 1 (benzene to indene), Class 2 (naphthalene to fluorene), Class 3 (phenanthrene to fluoranthene), Class 4 (pyrene to benzo(k)fluoranthene) and Class 5 (benzopyrene to coronene), where the tar dew point indication (°C) is based on 10 g / Nm 3Tars and average viscosity (cP) are provided by category. Although more tars are formed at lower temperatures (i.e. 750°C), this proves to be beneficial for the quench unit because these tars are light tar fractions (i.e. lower molecular weight) and therefore have lower tar dew points as well as lower viscosities. Lower tar dew points reduce the risk of scaling between the pyrolysis chamber and the quench unit, while lower viscosities reduce the risk of scaling within the quench unit itself.

[0115] Operating the pyrolysis chamber 2 at a lower temperature produces a larger amount of light tar fraction and therefore the tar load in the absorption unit 56 is increased, bringing the stripping section 84 closer to the lower explosion limit in the case of combustion air inputs 18 and 20 for stripping. The tar is absorbed from the gas into a scrubbing agent (such as oil) in the absorption tower 78. The saturated oil is then sent to the stripping tower 80 where a stripping agent is used to remove the tar. The stripping agent can be the combustion air entering the combustion chamber 12. The stripping agent ensures that the process is operated at less than 50% of the lower explosion limit (LEL) of the tar in the air. This is achieved by using primary air and secondary air for stripping. The LEL has been determined to be 37g / Nm 3 The combustion air may be reintroduced into the combustion chamber 12, for example partially in the free space region above the combustion bed 34. This reduces the temperature of the combustion bed 34 in the combustion zone 12, since a portion of the light tar fraction is burned above the fluidized bed zone 34 rather than in the fluidized bed zone 34. Alternatively, water may be injected into the fluidized bed zone 34 to reduce the temperature of the fluidized bed zone 34. The water may be waste water originating from the condensation of water in the product recovery unit 24.

[0116] Table 7

[0117]

[0118] The increase in viscosity of the liquid in the quench system has proven to be problematic. First, the > 800 ° C produces high viscosity tar. Second, a high concentration of ash fractions are retained in the processed gas in the particulate removal unit 58 (i.e., the cyclone separator). In particular, a high load of fines in the product gas (e.g., caused by a high calcium content in the feedstock) leads to an increase in viscosity. In addition, it has been found that ash particles tend to accumulate in the pyrolysis chamber. Therefore, a cyclone separator was developed with the aim of allowing the ash particles to experience sufficient time to agglomerate within the cyclone separator to assist in the separation of the ash particles from the depolymerized polymer product gas. Therefore, the cyclone separator is smaller than a conventional cyclone separator to have more interactions between the particles, but it is taller than a conventional cyclone separator to produce sufficient residence time for the particles to agglomerate. Table 8 shows the particle size distribution of ash retained in the depolymerized polymer product gas as a function of the inlet particle size distribution, in mg / Nm 3(mg / standard cubic meter).

[0119] Table 8

[0120]

[0121]

[0122] Table 9 shows the sand flow rate and sand to fuel ratio as a function of the fluidizing gas velocity through the transport zone 42. The operating temperature of the pyrolysis chamber 1 can be changed by adding more fluidizing gas below the transport zone 42 and less fluidizing gas above or into the transport zone 42. This redistribution of the fluidizing gas changes the temperature difference between the pyrolysis chamber 2 and the combustion chamber 12 because the flow rate of the fluidizing gas (i.e., sand) through the transport zone 42 can be increased without having to mechanically change the size of the transport zone 42. By increasing the velocity, the sand flow rate and sand to fuel ratio can be significantly increased.

[0123] Table 9

[0124]

[0125] By changing the system operating conditions upstream of the product recovery unit 24, the amount of pollutants in the product gas can be reduced. It is found that oxygen can enter the product gas by transporting the hot bed material (i.e., sand) from the combustion chamber 12 to the pyrolysis chamber 2 or by allowing air to enter the scrubber (i.e., oil), which is stripped with a stripping agent to remove the tar fraction. As shown in Table 10, the solubility of the pollutant gas in the stripped scrubber oil is low. The presence of carbon dioxide and nitrogen is not worrying because these gases are already present in the product gas at a significant level. However, the amount of oxygen should be kept low (i.e., at the ppb level). Prevent or reduce oxygen from entering the scrubber oil by using the degassing section 86 of the stripping tower 80. In addition, steam can be injected at the top of the conveying zone 42 to strip the circulating hot bed material (i.e., sand) from the flue gas. This not only reduces the amount of oxygen in the product gas entering the pyrolysis chamber 2, but also reduces the amount of NO. For example, oxygen and NO can react to form solid N 2 O 3 and N 2 O 4 These solids have a tendency to accumulate and may react with ammonia to form the explosive chemical ammonium nitrate. In addition, it has been shown in industry that N 2 O 3 It reacts vigorously with ethylene and propylene at 25° C. Steam can also be used to dilute the product gas in the pyrolysis chamber 2.

[0126] Table 10 shows the solubility of the contaminant gases collected in the stripped wash oil as a function of the oil temperature.

[0127]

[0128] Unlike conventional naphtha cracking which requires high steam dilution, the present invention requires only low steam dilution. Table 11 shows that the driving factor in the formation of ethylene and propylene is the temperature at which the reactions are carried out, rather than the steam-to-carbon ratio. Taking the velocity of the fluidizing gas in the transport zone to be 0.5 to 3 m / s, the magnitude of the steam-to-carbon ratio is typically from 0.05-0.10 at the low end, and from 0.75-1.50 at the high end.

[0129] Table 11 shows the carbon yields of different components of a mixture containing wood, polypropylene and polyethylene at different cracking temperatures and steam-to-carbon (StC) ratios.

[0130]

[0131]

Claims

1. A method for producing high-value chemicals from a feedstock, wherein the feedstock is or comprises waste, the method comprising: (a) providing a fluidized reactor system, the fluidized reactor system comprising a pyrolysis chamber (2) and a combustion chamber (12), and (b) inputting the feedstock into the pyrolysis chamber (2) and performing a pyrolysis process at a temperature ranging from 650°C to 850°C to obtain a product gas containing high-value chemicals.

2. The method according to claim 1, wherein: The pyrolysis process is performed at a temperature ranging from 700°C to 800°C, preferably 730°C to 770°C.

3. The method according to claim 1 or 2, further comprising: The product gas is transferred from the pyrolysis chamber to a tar removal system to remove one or more tar fractions from the product gas.

4. The method according to claim 3, wherein: The product gas transferred to the tar removal system contains Class 3-5 heavy tar fractions, and the content of Class 3-4 heavy tar fractions is greater than the content of Class 5 heavy tar fractions based on the weight of the total Class 3-5 heavy tar fractions.

5. The method according to claim 3 or 4, wherein: The product gas transferred to the tar removal system contains, by weight of the total Class 3-5 heavy tar fraction: (i) from 50% to 80% Class 3 heavy tar, (ii) from 10% to 40% Class 4 heavy tar and (iii) 10% or less Class 5 heavy tar.

6. The method according to any one of claims 3 to 5, wherein: The product gas transferred to the tar removal system contains from 20 to 30 g / Nm 3 Class 3-5 heavy tar.

7. The method according to any one of claims 3 to 6, wherein: The ratio of dust to Class 3-5 heavy tars of the product gas transferred to the tar removal system is from 1:99 to 10:

90.

8. The method according to any one of claims 3 to 7, wherein: The product gas transferred to the tar removal system contains from 0 to 2 g / Nm 3 of dust.

9. A method according to any preceding claim, wherein: The waste material is municipal solid waste.

10. A method according to any preceding claim, wherein: The waste material is biomass, biomass-rich refuse derived fuel, plastic-rich refuse derived fuel and plastic, or a combination thereof.

11. A method according to any preceding claim, wherein: The waste contains plastic.

12. A method according to any preceding claim, wherein: The waste comprises from 30% to 100%, preferably from 50% to 80% plastic by weight of the waste.

13. A method according to any preceding claim, wherein: The feedstock contains 5% to 30% water originating from the waste material and / or separately added to the feedstock.

14. A method according to any preceding claim, wherein: The anthropogenic carbon present in the waste comprises from 40% to 100%, preferably from 60% to 90% of the carbon in the waste.

15. A method according to any preceding claim, wherein: The high value chemicals in the product gas are olefins and / or single ring aromatic compounds.

16. A method according to any preceding claim, wherein: The olefins are ethylene, propylene, C4 olefins, C5 olefins or combinations thereof, and / or the monocyclic aromatic compounds are benzene, toluene, xylene, styrene or combinations thereof.

17. A method according to any preceding claim, further comprising: (c) Transferring the product gas to a product recovery unit and separating the high value chemicals.

18. The method according to claim 17, further comprising: The product gas is transferred from the pyrolysis chamber (2) to a tar removal system (52) to remove one or more tar fractions from the product gas before undergoing step (c).

19. A method according to any preceding claim, wherein: The tar removal system (52) includes an absorption unit (56) to remove light tar fractions, such as light tar fractions, from the product gas, preferably to remove light tar fractions, such as light tar fractions, and dust from the product gas.

20. The method according to claim 19, wherein: Part of the light tar fractions is transferred to the combustion chamber (12).

21. A method according to any preceding claim, wherein: The tar removal system (52) includes a quench unit (54) to remove heavy tar fractions from the product gas.

22. The method according to claim 21, wherein: The product gas is quenched via a quench medium, typically oil, at a temperature ranging from 50 to 95°C, preferably 60 to 90°C, more preferably 60 to 85°C.

23. The method according to claim 22, wherein: The spent quench medium obtained after the quench has a viscosity ranging from 40 to 200 cP, preferably from 80 to 160 cP.

24. The method according to any one of claims 21 to 23, wherein: Part of the heavy tar fractions is transferred to the combustion chamber (12).

25. A method according to any preceding claim, wherein: In the combustion chamber, the combustion process is performed at a temperature in the range from 30° C. to 130° C., preferably 50° C. to 110° C., higher than the pyrolysis process.

26. A method according to any preceding claim, further comprising: Bed material is circulated from the combustion chamber (12) to the pyrolysis chamber (2) via a conveying zone (42), wherein the pyrolysis process and the combustion process are carried out in the bed material.

27. The method according to claim 25, wherein: While circulating the bed material, sufficient heat is transferred from the combustion chamber (12) to the pyrolysis chamber (2) to perform the pyrolysis process.

28. The method according to claim 26 or 27, wherein: The temperature difference between the combustion chamber (12) and the pyrolysis chamber (2) is increased by reducing the circulation rate of the bed material, and wherein the temperature difference between the combustion chamber (12) and the pyrolysis chamber (2) is reduced by increasing the circulation rate of the bed material.

29. The method according to any one of claims 26 to 28, wherein: The circulation rate of the bed material is from 10 to 100 kg of bed material per kg of feedstock, more preferably from 20 to 60 kg of bed material per kg of feedstock.

30. The method according to any one of claims 26 to 29, wherein: Fluidizing gas is transferred to the transport zone (42) to control the circulation rate of the bed material.

31. The method according to claim 30, wherein: The fluidizing gas is transferred to more than one area in the transport zone (42).

32. The method according to claim 31, wherein: The temperature difference between the combustion chamber (12) and the pyrolysis chamber (2) is increased or decreased by varying the ratio of fluidizing gas diverted to the first region of the transport zone relative to the fluidizing gas diverted to the second region of the transport zone.

33. The method according to any one of claims 26 to 32, wherein: The transport zone includes a first region (44) to allow bed material to flow downward from the combustion chamber (12), and a second region (46) to allow bed material to flow upward to the pyrolysis chamber (2).

34. The method of claim 33, wherein: Fluidizing gas is transferred to an upstream portion (48) of the second zone (46) and a downstream portion (47) of the second zone (46).

35. The method according to any one of claims 30 to 34, wherein: The velocity of the fluidizing gas in the conveying zone (42) is from 0.5 to 3 m / s, preferably from 1 to 2.5 m / s, even more preferably 2 m / s.

36. The method of claim 34, wherein: The velocity of the fluidizing gas in the upstream portion (48) and / or downstream portion (47) is from 0.5 to 3 m / s, preferably from 1 to 2.5 m / s, even more preferably 2 m / s.

37. A method according to any preceding claim, wherein: Fluidizing gas is typically transferred from the product recovery unit (40) of the fluidized reactor system to the pyrolysis chamber (2) to control the circulation rate of the bed material.

38. The method of claim 37, wherein: The velocity of the fluidizing gas in the pyrolysis chamber (2) is from 5 to 8.5 m / s, preferably from 5.5 to 7.5 m / s.

39. A method according to any preceding claim, further comprising: (c) transferring the product gas to a product recovery unit (24) and separating the high value chemicals.

40. The method of claim 39, further comprising: A tail gas or waste gas is separated from the product gas.

41. The method of claim 40, further comprising: At least a portion of the tail or exhaust gas is diverted to the combustion chamber (12).

42. The method according to claim 40 or 41, wherein: At least a portion of the tail gas or waste gas is used for the production of chemicals, preferably hydrogen, CO and / or olefins.

43. A method according to any preceding claim, further comprising: The product gas is transferred from the pyrolysis chamber to a particulate removal unit, such as a cyclone separator, to remove dust from the product gas before transferring the product gas to the tar removal system.

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