System and method for heating a pyrolysis reactor
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-10
- Publication Date
- 2026-08-13
Smart Images
Figure FI2026050062_13082026_PF_FP_ABST
Abstract
Description
SYSTEM AND METHOD FOR HEATING A PYROLYSIS REACTORFIELD
[0001] The present invention relates to a system and method for heating a pyrolysis reactor.BACKGROUND
[0002] Polymers are used in a wide variety of products. The polymers are typically acquired through petroleum resources, which are considered non-renewable. In this connection, the need for a sustainable supply of raw material has arisen, as accumulation of polymer waste has been recognized as an environmental problem. As a consequence, polymer waste is often collected and sorted for recycling or thermal decomposition purposes. Environmental problems can be reduced by subsequent polymer waste material treatment and re-use of at least a part of the material. For example, polymer waste material can be treated by pyrolysis, i.e. by thermal decomposition of the polymer waste material at elevated temperatures in an inert atmosphere, in order to obtain a product comprising a gas from at least partially pyrolyzed polymer waste. Such treatment may, for example, take place in a pyrolysis reactor, such as a rotary kiln reactor, into which polymer waste is fed.
[0003] For example, document EP 4306618 Al discloses a system and method for treatment of polymer waste. The system comprises a hollow chamber comprising a first chamber and a second chamber, wherein the second chamber is rotatable or the first chamber and the second chamber are rotatable, a heating system configured to heat the second chamber or to individually heat the first chamber and the second chamber, a lance having at least one feed outlet, wherein the lance extends within the hollow chamber at least through the first chamber, and wherein the system is configured to feed polymer waste into the second chamber via the at least one feed outlet, and at least one injector capable of injecting at least one sweep fluid into the first chamber or into the first chamber and into the second chamber in order to form a fluid flow towards at least one gas outletfor collecting a product comprising the at least one sweep fluid and a gas from at least partially pyrolyzed polymer waste.
[0004] The product comprising a gas from at least partially pyrolyzed polymer waste is typically treated in at least one condensation step to obtain gaseous and condensed products. At least one non-condensable gas may be obtained from said gaseous product at a later stage.
[0005] In conventional pyrolysis reactors, heating is typically done by a plurality of burners arranged within a reactor muffle. Typically, natural gas or other purified fuel is used for heating the pyrolysis reactor by the plurality of burners. When non-standard fuel is used, harmful or restricted substances may exist in the flue gas. In such a case, harmful or restricted substances are therefore typically removed by oxidation or adsorption after the pyrolysis reactor or the reactor muffle.
[0006] In view of the foregoing, it would be beneficial to provide a system and a method for heating a pyrolysis reactor.SUMMARY OF THE INVENTION
[0007] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.
[0008] According to a first aspect of the present invention, there is provided a system comprising at least one gas source capable of providing at least one non-condensable gas obtained from a plastic pyrolysis process, a thermal oxidizer arranged downstream of the at least one gas source, fluidly connected to the at least one gas source and capable of combusting the at least one non-condensable gas, a muffle of a pyrolysis reactor arranged external to and downstream of the thermal oxidizer, wherein the pyrolysis reactor comprises at least one heating space within the muffle, wherein the muffle comprises at least one flue gas inlet and at least one flue gas outlet, wherein the at least one flue gas inlet is fluidly connected to the thermal oxidizer, wherein the system does not comprise a separate oxidation or adsorption system arranged downstream of the muffle.
[0009] Various embodiments of the first aspect may comprise at least one feature from the following bulleted list:the system comprises a compressor, a fan or a pump capable of pressurizing the at least one non-condensable gas• the thermal oxidizer is capable of combusting the at least one non-condensable gas in a range between 800 °C and 1200 °C• the thermal oxidizer comprises a further gas inlet for injecting a supplementary fuel• the thermal oxidizer is configured to supply flue gas to one or more pyrolysis reactors• the system comprises a bypass piping system arranged so that at least a part of the flue gas is allowed to bypass the pyrolysis reactor or the muffle• the pyrolysis reactor or the muffle does not include a burner capable of combusting a fuel• the pyrolysis reactor is a rotary kiln reactor• the system comprises a heat recovery system arranged downstream of and fluidly connected to the pyrolysis reactor or a heat recovery system arranged downstream of and fluidly connected to the muffle or a heat recovery system arranged downstream of and fluidly connected to the at least one heating space• the system comprises a scrubbing unit arranged downstream of and fluidly connected to the heat recovery system
[0010] According to a second aspect of the present invention, there is provided an arrangement comprising a system according to any one of claims 1 - 9, a first condensing unit fluidly connected to the pyrolysis reactor, an overhead condensing unit fluidly connected to the first condensing unit, a second phase separator fluidly connected to the overhead condensing unit, a liquid ring compressor fluidly connected to the second phase separator, a heat exchanger fluidly connected to the liquid ring compressor, a first phase separator fluidly connected to the heat exchanger, and a stabilizing column fluidly connected to the first phase separator, wherein at least one of the heat exchanger, the first phase separator and the stabilizing column serves as the gas source capable of providing at least one non-condensable gas.
[0011] According to a third aspect of the present invention, there is provided a method comprising providing at least one non-condensable gas obtained from a plastic pyrolysis process, combusting the at least one non-condensable gas by a thermal oxidizer, guiding a flue gas from the thermal oxidizer to at least one heating space within a muffle of a pyrolysis reactor, wherein the muffle of the pyrolysis reactor is arranged external to and downstream of the thermal oxidizer, and guiding the flue gas out of the at least one heating space without providing a separate oxidation or adsorption system arranged downstream of the muffle.
[0012] Various embodiments of the third aspect may comprise at least one feature from the following bulleted list:• the method comprises pressurizing the at least one non-condensable gas by a compressor• the method comprises combusting the at least one non-condensable gas by a thermal oxidizer in a range between 800 °C and 1200 °C• the method comprises allowing at least a part of the flue gas to bypass the pyrolysis reactor or the muffle via a bypass piping system• the method comprises injecting air into at least one section of the muffle to control a flue gas temperature and / or mixing air with the flue gas upstream of the muffle• the method comprises recovering heat from the flue gas by a heat recovery system arranged downstream of the pyrolysis reactor or arranged downstream of the muffle or arranged downstream of the at least one heating space• the method comprises removing contaminants from the flue gas by a scrubbing unit arranged downstream of the heat recovery system• residence time of the at least one non-condensable gas within a combustion chamber of the thermal oxidizer is typically greater than 2 seconds
[0013] Considerable advantages are obtained by certain embodiments of the invention. A system and method for heating a pyrolysis reactor are provided. According to certain embodiments, a system and a method for heating a rotary kiln reactor are provided, wherein a gaseous byproduct of the pyrolysis process, which is a non-standard fuel, isutilized. According to the present invention, the pyrolysis reactor can be heated by combusting in a thermal oxidizer at least one non-combustible gas obtained from a plastic pyrolysis process, wherein the thermal oxidizer is arranged external to and upstream of a muffle of the pyrolysis reactor. Consequently, it is not required to provide one or more additional burners capable of combusting a fuel in the muffle of the pyrolysis reactor. The at least one non-condensable gas is fed to the thermal oxidizer where the gas is combusted and all substances of very high concern, such as listed by the European Chemicals Agency (ECHA) or by the United States Environmental Protection Agency (EP A), organic and combustible substances and their precursors are eliminated, removed, fully oxidized or at least reduced to very low levels to comply with environmental requirements. The present invention eliminates the need for a separate oxidiation or adsorption system arranged downstream of the muffle, thus providing a less complex system. In other words, operational complexity can be reduced by integrating two combustion steps or a combustion step and another equivalent downstream emission control step such as filtration in a single unit.
[0014] According to the present invention, generated non-condensable gas obtained from waste plastics pyrolysis gas can be utilized as an energy source for the pyrolysis reaction of low-quality waste plastics, while maximizing energy recovery and eliminating, removing, fully oxidizing or at least reducing harmful substances to low levels in a compact process to meet emission requirements or environmental requirements.
[0015] According to certain embodiments, no additional separate steam boiler is required, further reducing equipment costs and energy consumption. Continuous combustion of all generated non-condensable gas can be achieved by a bypass system, allowing for efficient heat recovery and duty control of the heat of the reactor after the combustion. No separate gas recovery or storage is needed for any excess gas.
[0016] According to certain embodiments, fouling of heat transfer surfaces can be reduced due to optimized combustion and temperature control.
[0017] Certain embodiments provide the potential for using a single thermal oxidizer for multiple pyrolysis reactors, thereby creating opportunities for shared equipment and reduction of costs and complexity.
[0018] Certain embodiments further provide a simplified concept with single combustion and emission control point making it easier to operate and maintain the system.
[0019] Certain embodiments furthermore make it possible to maintain temperatures above the de novo synthesis window, even in cases of incomplete combustion, minimizing the risk of forming harmful compounds. Elimination, removal, full oxidization or at least reduction of harmful substances of very high concern, organic and combustible substances and their precursors as well as energy recovery are integrated into a single step, thus enhancing efficiency and minimizing environmental impact.
[0020] Certain embodiments offer a potential location for incineration of wastewater, further reducing waste streams.BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIGURE 1 illustrates a schematic view of a system for heating a process gas in accordance with at least some embodiments of the present invention,
[0022] FIGURE 2 illustrates a schematic view of another system for heating a process gas in accordance with at least some embodiments of the present invention,
[0023] FIGURE 3 illustrates a schematic view of a further system for heating a process gas in accordance with at least some embodiments of the present invention, and
[0024] FIGURE 4 illustrates a schematic view of an arrangement in accordance with at least some embodiments of the present invention.EMBODIMENTS
[0025] In the context of the present invention, thermal oxidation is the oxidation process of a mixture of at least one combustible, non-condensable gas obtained from a plastic pyrolysis process, possible contaminants present in the at least one non-condensable gas as well as air or oxygen in a combustion chamber and maintaining it at a high temperature for sufficient time to complete combustion.
[0026] The at least one non-condensable gas entering a thermal oxidizer through a gas inlet may be pre-heated, for example by a pre-heating system such as a ceramic heat exchange matrix, upstream of the combustion chamber to a temperature below oxidation temperature. The at least one non-condensable gas is then guided into the combustion chamber of the thermal oxidizer. The temperature within the combustions chamber of a thermal oxidizer is typically greater than 800°C, greater than 850°C, greater than 1000°C or even greater than 1100°C, for example up to 1200°C, and maintained by one or more burners. A residence time of the at least one non-condensable gas within the combustion chamber of the thermal oxidizer is typically greater than 2s. An oxygen content is typically greater than 3 %. The at least one non-condensable gas is combusted within the combustion chamber and all substances of very high concern, such as listed by the European Chemicals Agency (ECHA) or by the United States Environmental Protection Agency (EP A), organic and combustible substances and their precursors are eliminated, removed, fully oxidized or at least reduced to very low levels to comply with environmental requirements. The thermal oxidizer may comprise a second ceramic heat exchanger matrix configured to transfer thermal energy to be reused for preheating the next cycle. A clean high-temperature flue gas stream, i.e. a flue gas stream, wherein all substances of very high concern, organic and combustible substances and their precursors are eliminated, removed, fully oxidized or at least reduced to very low levels, is then guided through a gas outlet of the thermal oxidizer.
[0027] According to the present invention, a pyrolysis reactor comprising a muffle is arranged external to and downstream of the thermal oxidizer. The pyrolysis reactor can be heated by said clean high-temperature flue gas stream. Consequently, it is not required to provide one or more additional burners capable of combusting a fuel in the muffle of the pyrolysis reactor. The present invention further eliminates the need for a separate oxidization or adsorption system arranged downstream of the muffle, thus providing a less complex system. In other words, purification or cleaning of flue gas downstream of the muffle does not take place according to certain embodiments of the present invention and there is no further flue gas purification or cleaning system present according to other embodiments of the present invention.
[0028] In FIGURE 1 a schematic view of a system 1 for heating a pyrolysis reactor 17 in accordance with at least some embodiments of the present invention is illustrated. The system 1 comprises at least one gas source 40 capable of providing at least one non-condensable gas 6, 11 obtained from a plastic pyrolysis process. The at least one gas source 40 may be, for example, a phase separator 4 or a stabilizing column 9 as shown and described below in connection with FIGURE 4. For example, A compressor, fan or pump capable of pressurizing the at least one non-condensable gas 6, 11 may be further provided downstream of the at least one gas source 40. In this connection, the term “downstream” refers to a position in a flow direction of the at least one non-condensable gas 6, 11 from the at least one gas source 40 as shown in FIGURES 1 - 4. In other words, a compressor, fan or pump may be arranged between the at least one gas source 40 and a thermal oxidizer 41, for instance.
[0029] Further, the system 1 comprises the mentioned thermal oxidizer 41 arranged downstream of the at least one gas source 40. In this connection, the term “downstream” refers to a position in a flow direction of the at least one non-condensable gas 6, 11 from the at least one gas source 40 as shown in FIGURES 1 - 4. The thermal oxidizer 41 is fluidly connected to the at least one gas source 40 by a piping system and capable of combusting the at least one non-condensable gas 6, 11. The thermal oxidizer 41 is typically capable of combusting the at least one non-condensable gas 6, 11 in a temperature range between 800 °C and 1200 °C. A residence time of the at least one non-condensable gas 6, 11 within the combustion chamber of the thermal oxidizer 41 is typically greater than 2s. An oxygen content is typically greater than 3 %. The thermal oxidizer 41 may, for example, comprise a supplementary fuel inlet 46 for injecting a supplementary fuel 51 into the thermal oxidizer 41. In such a case, the supplementary fuel 51 may be a combustible gas such as natural gas, LPG, or propane, for instance. Injecting supplementary fuel may be useful in connection with start-up, shut-down, process upset, disturbance or stand-by of the thermal oxidizer 41. Combusting the at least one non-condensable gas 6, 11 by the thermal oxidizer 41 is beneficial to eliminate, remove, fully oxidize or at least reduce all substances of very high concern, organic and combustible substances and their precursors to very low levels to comply with environmental requirements. As shown, the thermal oxidizer 41 is arranged between the at least one gas source 40 and a muffle 45 of a pyrolysis reactor 17.
[0030] Furthermore, the system 1 comprises the mentioned muffle 45 of the pyrolysis reactor 17 arranged external to and downstream of the thermal oxidizer 41. In this connection, the term “downstream” refers to a position in a flow direction of a flue gas 50 from the thermal oxidizer 41 as shown in FIGURES 1 - 4. The pyrolysis reactor 17 maybe, for example, a rotary kiln reactor. The pyrolysis reactor 17 may be an indirectly heated pyrolysis reactor, for instance. For example, the pyrolysis reactor 17 may be a reactor as described in paragraphs
[0013] -
[0027] of document EP 4306618 Al, which are herewith incorporated by reference. The pyrolysis reactor 17 comprises at least one heating space 42 within a muffle 45. The muffle 45 comprises at least one flue gas inlet 43 and at least one flue gas outlet 44. The at least one flue gas inlet 43 is fluidly connected to the thermal oxidizer 41 by a piping system. The pyrolysis reactor 17 as such does not include a burner capable of combusting a combustible gas. In other words, hot flue gas 50 from the thermal oxidizer 41 can be guided into the heating space 42 of the pyrolysis reactor 17 in order to provide heat for pyrolyzing feed material 53 such as polymer waste to obtain a product 52 comprising a gas from at least partially pyrolyzed material. The at least one noncondensable gas 6, 11 can be obtained via a number of treatment steps, for example as shown and described below in connection with FIGURE 4, from the product 52 comprising gas from at least partially pyrolyzed material. According to certain embodiments, the thermal oxidizer 41 may be configured to supply the flue gas 50 to one or more pyrolysis reactors.
[0031] The reactor thermal profile and / or the temperature of the flue gas 50 can be controlled individually using cooling air injection into at least one section of the muffle 45 and / or mixing air with the flue gas upstream of the muffle 45. In this connection, the term “upstream” refers to a position in the flow of flue gas 50 between the thermal oxidizer 41 and the muffle 45 as shown in FIGURE 4. In other words, mixing air with the flue gas 50 can take place between the thermal oxidizer 41 and the muffle 45. The overall duty of the heat of the reactor 17 may be handled by adjusting flue gas bypass of the heating muffle 45 as shown in FIGURE 2.
[0032] It should be noted that there is no separate oxidization or adsorption system arranged downstream of the muffle of the pyrolysis reactor 17.
[0033] In FIGURE 2 a schematic view of another system 1 for heating a pyrolysis reactor 17 in accordance with at least some embodiments of the present invention is illustrated. The system 1 comprises the features shown and described above in connection with FIGURE 1. Additionally, the system 1 comprises a bypass piping system 47 arranged so that at least a part of the flue gas 50 is allowed to bypass the pyrolysis reactor 17. The amount of flue gas 50 bypassing the pyrolysis reactor 17 or the muffle 45 or the heatingspace 42 may be adjusted by a valve arranged between the thermal oxidizer 41 and the pyrolysis reactor 17.
[0034] In FIGURE 3 a schematic view of a further system 1 for heating a pyrolysis reactor 17 in accordance with at least some embodiments of the present invention is illustrated. The system 1 comprises the features shown and described above in connection with FIGURE 1 or FIGURE 2. Additionally, the system 1 may comprise a heat recovery system 48 arranged downstream of and fluidly connected to the pyrolysis reactor 17, a heat recovery system 48 arranged downstream of and fluidly connected to the muffle 45 or a heat recovery system 48 arranged downstream of and fluidly connected to the at least one heating space 42. In this connection, the term “downstream” refers to a position in a flow direction of the flue gas 50 from the pyrolysis reactor 17, the muffle 45 or the heating space 42 as shown in FIGURES 1 - 4. The heat recovery system 48 may comprise a steam boiler. Upon leaving the reactor muffle 45, the flue gas can combine with the reactor muffle bypass and enters the heat recovery system 48. The excess energy may be used to generate steam, for instance. Alternatively, the waste heat recovery step may comprise hot water heating, thermal heating, a heat pump or some other circuit requiring heating. As shown, the heat recovery system 48 is arranged between the thermal oxidizer 41 and a scrubbing unit 49.
[0035] Further, the system 1 may comprise the mentioned scrubbing unit 49 arranged downstream of and fluidly connected to the heat recovery system 48. In this connection, the term “downstream” refers to a position in a flow direction of the flue gas 50 from the heat recovery system 48 as shown in FIGURES 1 - 4. Upon leaving the heat recovery system 48, the flue gas can enter the scrubbing unit 49 to remove HC1 and other contaminants and to cool the flue gas. Scrubbing water drawn from a sump of the scrubbing unit 49 may be pumped into a scrubber spray manifold. Caustic may be dosed into the spray loop to maintain pH control of the system. Addition of caustic also enhances scrubbing performance by neutralizing acid gases dissolved in the scrubbing water.
[0036] In FIGURE 4 a schematic view of an arrangement 16 in accordance with at least some embodiments of the present invention is illustrated. The arrangement 16 comprises a system 1 as shown and described above in connection with FIGURE 1, FIGURE 2 or FIGURE 3.
[0037] The arrangement 16 further comprises a condensing system 18 fluidly connected to the pyrolysis reactor 17. The condensing system 18 is typically arranged directly after or downstream of the pyrolysis reactor 17. In this connection, the term “downstream” refers to a position in a flow direction of a first product 52 from the pyrolysis reactor 17 as shown in FIGURE 4. The condensing system 18 comprises a first condensing unit 22. The first condensing unit 22 may be a quench tower, for instance. The first condensing unit 22 comprises a first gas inlet 23 for guiding a first product 52 comprising the pyrolysis gas into the first condensing unit 22. The pyrolysis gas is provided from the pyrolysis reactor 17. The first product 52 may, for example, comprise a gas from at least partially pyrolyzed polymer waste material. The first product 52 may additionally comprise other gases including purge gases, flush gases or sweeping gases utilized in the pyrolysis reactor, for instance. Further, the first condensing unit 22 comprises a first outlet 25 for guiding a condensed second product 26 out of the first condensing unit 22. The condensed second product 26 is typically a product comprising heavy hydrocarbons. Additionally, the first condensing unit 22 comprises a second outlet 27 for guiding a gaseous third product 28 out of the first condensing unit 22.
[0038] The condensing system 18 further comprises an overhead condensing unit 31. The condensing system 18 is configured to transfer the gaseous third product 28 to a second phase separator 35 via the overhead condensing unit 31. The second phase separator 35 may be a three-phase separation vessel, for instance. The gaseous third product 28 can be guided from the second outlet 27 of the first condensing unit 22 to a second gas inlet 30 of the overhead condensing unit 31 via a first piping system 29. The overhead condensing unit 31 comprises a heat exchanger capable of condensing the gaseous third product 28 at a temperature below 100 °C, for instance.
[0039] The condensing system 18 may, for example, further comprise at least one water injection system arranged upstream of the heat exchanger of the overhead condensing unit 31. In this connection, the term “upstream” refers to a position in a flow of the third product 28 between the heat exchanger of the overhead condensing unit 31 and the first condensing unit 22 as shown in FIGURE 4. In other words, at least one water injection system is arranged between the first condensing unit 22 and the heat exchanger of the overhead condensing unit 31. The at least one water injection system is capable of washing, cooling and at least partly condensing the gaseous third product 28 by contacting said gaseous third product 28 with water. For example, the overhead condensing unit 31comprises at least one tube arranged within a shell structure and the gaseous third product 28 is capable of flowing along the at least one tube. The at least one tube may be arranged vertically or substantially vertically. In such a case, the condensing system 18 is typically configured to guide the gaseous third product 28 along the at least one tube from a top of the overhead condensing unit 31. The water injection system typically comprises one or more spray nozzles capable of spraying water onto an inner surface of the at least one tube, onto a tube sheet of the overhead condensing system 31 and / or directly into a gas flow of the gaseous third product 28. Spraying water onto the inner surface of the at least one tube and / or the tube sheet may, for example, take place from on top or in an upper part of the overhead condensing unit 31, i.e. upstream of the heat exchanger, to enable proper washing of the at least one tube. Spraying water directly into the gas flow may, for example, take place by another water injection system comprising one or more spray nozzles centred in the first piping system 29, i.e. upstream of the overhead condensing unit 31. As a consequence, water can be injected in a downstream direction in a co-current way. In this connection, the term “downstream” refers to a position in a flow direction of the third product 28 from the first condensing unit 22 as shown in FIGURE 4. A mixture of condensed oil and water injected by the at least one water injection system can exit the overhead condensing unit 31 via a fluid outlet 32 and flow along a second piping system 33 together with the remaining gaseous third product to the second phase separator 35 comprising a fluid inlet 34. Consequently, the first piping system 29 and / or the second piping system 33 is / are washed by the water flow. Salt formation on at least some components of the condensing system 18, and thus fouling can be therefore avoided or at least reduced. Further, water soluble impurities including HCI, NH3 and H2S can be scrubbed off from the stream of the gaseous third product. Sprayed water can also clean entrained solid particles from the incoming stream of the gaseous third product.
[0040] Water utilized in the injection of water typically consists of pyrolytic water generated in the pyrolysis reactions and added makeup water. A pyrolytic water stream is typically generated at the first injection point or in the overhead condenser itself and is later separated from the third product in a downstream separation step. In this connection, the term “downstream” refers to a position in a flow direction of the third product 28 from the overhead condensing unit 31 as shown in FIGURE 4. Makeup water is added to control an impurity content of the washing water. Makeup water quality may meet specifications of a boiler feed water quality to mitigate at least one of corrosion, scaling, fouling andfoaming, for instance. Makeup water within this document means that the water is essentially contaminant free. Sour water and / or process water is removed from the process in a downstream separation step.
[0041] According to some embodiments, the at least one tube of the overhead condensing unit 31 may be arranged vertically or substantially vertically and the gaseous third product 28 is capable of flowing along the at least one tube from a bottom of the overhead condensing unit 31. According to certain other embodiments, it is also possible to arrange the at least one tube of the overhead condensing unit 31 horizontally or substantially horizontally.
[0042] The second phase separator 35 comprises a fluid inlet 34 through which the remaining gaseous third product and the water and oil mixture from the overhead condensing unit 31 can enter. The second phase separator 35 is capable of separating the remaining gaseous third product and the water and oil mixture to obtain a condensed fourth product comprising at least an aqueous phase 36 and a separated oil phase 37. Water 38 and oil 39 can be removed from the second phase separator 35. Remaining process gases 15 such as non-condensable gases can be guided out of the second phase separator 35 to a liquid ring compressor 2.
[0043] The liquid ring compressor 2 or liquid ring pump is capable of pressurizing the process gas 15. The process gas 15 comprises hydrocarbons predominantly C8 and below, hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam. According to certain embodiments of the present invention, a stabilized liquid hydrocarbon product is utilized as a service liquid for the liquid ring compressor 2. The stabilized liquid hydrocarbon product may be cooled prior to utilizing it as the service liquid. The process gas 15 may be, for example, obtained from a product 52 comprising a gas from at least partially pyrolyzed polymer waste material, which product 52 has been transferred to a condensing system 18 arranged downstream of the pyrolysis reactor 17 and providing the process gas 15. In this connection, the term “downstream” refers to a position in a flow direction of the first product 52 from the pyrolysis reactor 17 as shown in FIGURE 4. The process gas 15 typically comprises a non-condensable gas and may, for example, comprise hydrocarbons, predominantly C8 and below, hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam. The liquid ring compressor 2 is capable of pressurizing the process gas 15 to about 2 to 10 bar(a), for example 5.5 to 6 bar(a). The temperature of the process gasand stabilized liquid hydrocarbon product mixture may rise to approximately 60°C to 70°C in the liquid ring compressor 2, for instance. According to another embodiment, at least a part of the water 21 is directed from the first phase separator 4 to the liquid ring compressor 2 via a piping system. In such a case, the water 21 is utilized as a service liquid for the liquid ring compressor 2. The process gas 15 typically comprises a non-condensable gas and may, for example, comprise hydrocarbons, predominantly C8 and below, hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam. The liquid ring compressor 2 is capable of pressurizing the process gas 15 to about 2 to 10 bar(a), for example 5.5 to 6 bar(a). The temperature of the process gas and water mixture may rise to approximately 60°C to 70°C in the liquid ring compressor 2, for instance. The water 21 used as the service liquid for the liquid ring compressor 2 may be cooled, for instance.
[0044] The arrangement 16 further comprises a heat exchanger 3 capable of cooling and partially condensing a mixture 14 of a process gas 15 and a stabilized liquid hydrocarbon product 13 or a mixture 14 of a process gas 15 and the water 21. The heat exchanger 3 may, for example, comprise at least one tube arranged within a shell structure, a plate type heat exchanger or an air cooler. The cooling medium may be air or water. The mixture 14 from the liquid ring compressor 2 is able to flow through the tube. The heat exchanger 3 may, for example, operate with cooling water present in the shell structure. The heat exchanger 3 may be, for example, capable of cooling the mixture 14 to a temperature in the range between 20°C and 60°C. For example, the compressed two-phase flow from the liquid ring compressor 2 may be cooled to a temperature of 40°C. The service liquid works as an absorbent for the heavier components in the process gas 15. Gas and liquid are in phase equilibrium with each other at the discharge side.
[0045] Furthermore, the arrangement 16 comprises a phase separator 4 comprising a water boot for separating any possible free water 21. After cooling, the mixture 14 is led into the phase separator 4. In other words, the arrangement 1 is configured to transfer the mixture 14 from the liquid ring compressor 2 via the heat exchanger 3 to the phase separator 4. The phase separator 4 comprises a water outlet 20 for guiding water 21 out of the arrangement 16, a first gas outlet 5 for guiding at least one first non-condensable gas 6 out of the arrangement 16 and a first liquid outlet 7 for guiding at least a part of a separated first liquid hydrocarbon product 8 to a stabilizing column 9. Gaseous hydrocarbons and non-hydrocarbons such as hydrogen, nitrogen, carbon monoxide and carbon dioxide may be removed via the first gas outlet 5. Light first non-condensable gases 6, for example C4and lighter hydrocarbons, may be directed to the thermal oxidizer 41 and / or a fuel gas network via the first gas outlet 5 or other users, for instance. The slip stream may be sent to spillback. The spillback controls the liquid ring compressor 2 suction pressure. In other words, the phase separator 4 can serve as a gas source capable of providing at least one first non-condensable gas 6 obtained from a plastic pyrolysis process. According to certain embodiments, at least a part of the oil 39 removed from the second phase separator 35 can be further guided to and mixed with the first liquid hydrocarbon product 8 prior to entering of the oil and first liquid hydrocarbon product mixture into the stabilizing column 9.
[0046] The stabilizing column 9 comprises a second gas outlet 10 for guiding at least one second non-condensable gas 11 out of the arrangement 16, to a fuel gas network, to the thermal oxidizer 41 or to other users. According to certain embodiments, the stabilizing column 9 further comprises a second liquid outlet 12 for guiding at least a part of a stabilized second liquid hydrocarbon product 13 back to the liquid ring compressor 2. The stabilizing column 9 is typically provided to remove C4 and lighter components dissolved in the first liquid hydrocarbon product 8, i.e. the feed stream. The stabilizing column 9 may be equipped with a reboiler and an overhead condenser, for instance. The overhead condenser may be an external, an integrated or a direct contact condenser. Light second non-condensable gases 11 may be directed to the thermal oxidizer 41 and / or the fuel gas network via the second gas outlet 10 or other users, for instance. An operating pressure of the stabilizing column 9 may be dictated by an available or selected pressure of the liquid ring compressor 2, a downstream gas user requirement and / or available cold and hot utility temperature levels. In this connection, the term “downstream” refers to a position in a flow direction of the second non-condensable gas 11 from the stabilizing column 9 as shown in FIGURE 4. The operating pressure of the stabilizing column 9 may be in the range between 150 kPa(a) and 600 kPa(a), for instance. The stabilized liquid hydrocarbon product 13 obtained from the stabilizing column 9 can be utilized as the service liquid for the liquid ring compressor 2. In other words, the stabilizing column 9 can serve as a gas source capable of providing at least one second non-condensable gas 11 obtained from a plastic pyrolysis process.
[0047] According to certain embodiments, at least a part of the condensed second product 26 may be further mixed with the stabilized second liquid hydrocarbon product 13 prior to guiding the resulting mixture out of the arrangement 16. According to certainembodiments, the condensed second product 26 and the stabilized second liquid hydrocarbon product 13 may be separately guided out of the arrangement 16.
[0048] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.
[0049] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.
[0050] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and examples of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.
[0051] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the invention.
[0052] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.
[0053] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.INDUSTRIAL APPLICABILITY
[0054] At least some embodiments of the present invention find industrial application in heating a pyrolysis reactor utilized in connection with polymer waste treatment.REFERENCE SIGNS LIST 1 system2 liquid ring compressor3 heat exchanger4 first phase separator5 first gas outlet6 first non-condensable gas7 first liquid outlet8 first liquid hydrocarbon product9 stabilizing column10 second gas outlet11 second non-condensable gas12 second liquid outlet13 second liquid hydrocarbon product14 mixture15 process gas16 arrangement17 py roly si s reactor18 condensing system20 water outlet21 water22 first condensing unit23 first gas inletfirst outletsecond productsecond outletthird productfirst piping system second gas inlet overhead condensing unit fluid outletsecond piping system fluid inletsecond phase separator an aqueous phaseoil phasewateroilgas sourcethermal oxidizer heating spaceflue gas inletflue gas outletmufflesupplementary fuel inlet bypass piping system48 heat recovery system49 scrubbing unit50 flue gas51 supplementary fuel52 product comprising gas from at least partially pyrolyzed material 53 feed materialCITATION LISTPatent LiteratureEP 4306618 Al
Claims
CLAIMS:
1. A system (1) comprising:- at least one gas source (40) capable of providing at least one non-condensable gas (6, 11) obtained from a plastic pyrolysis process,- a thermal oxidizer (41) arranged downstream of the at least one gas source (40), fluidly connected to the at least one gas source (40) and capable of combusting the at least one non-condensable gas (6, 11), and- a muffle (45) of a pyrolysis reactor (17) arranged external to and downstream of the thermal oxidizer (41), wherein the pyrolysis reactor (17) comprises at least one heating space (42) within the muffle (45), wherein the muffle (45) comprises at least one flue gas inlet (43) and at least one flue gas outlet (44), wherein the at least one flue gas inlet (43) is fluidly connected to the thermal oxidizer (41)- wherein the system (1) does not comprise a separate oxidation or adsorption system arranged downstream of the muffle (45).
2. The system (1) according to claim 1, wherein the system (1) comprises a compressor, a fan or a pump capable of pressurizing the at least one non-condensable gas (6, 11).
3. The system (1) according to claim 1 or 2, wherein the thermal oxidizer (41) is capable of combusting the at least one non-condensable gas (6, 11) in a range between 800 °C and 1200 °C.
4. The system (1) according to claim 1 or 2, wherein the thermal oxidizer (41) comprises a further gas inlet (46) for injecting a supplementary fuel.
5. The system (1) according to any one of claims 1 - 4, wherein the system comprises a bypass piping system (47) arranged so that at least a part of the flue gas is allowed to bypass the pyrolysis reactor (17) or the muffle (45).
6. The system (1) according to any one of claims 1 - 5, wherein the pyrolysis reactor (17) or the muffle (45) does not include a burner capable of combusting a fuel.
7. The system (1) according to any one of claims 1 - 6, wherein the pyrolysis reactor (17) is a rotary kiln reactor.
8. The system (1) according to any one of claims 1 - 7, wherein the system (1) comprises a heat recovery system (48) arranged downstream of and fluidly connected to the pyrolysis reactor (17) or a heat recovery system (48) arranged downstream of and fluidly connected to the muffle (45) or a heat recovery system (48) arranged downstream of and fluidly connected to the at least one heating space (42).
9. The system (1) according to claim 8, wherein the system (1) comprises a scrubbing unit (49) arranged downstream of and fluidly connected to the heat recovery system (48).
10. An arrangement comprising:- a system according to any one of claims 1 - 9,- a first condensing unit (22) fluidly connected to the pyrolysis reactor (17),- an overhead condensing unit (31) fluidly connected to the first condensing unit (22),- a second phase separator (35) fluidly connected to the overhead condensing unit (31),- a liquid ring compressor (2) fluidly connected to the second phase separator (35), - a heat exchanger (3) fluidly connected to the liquid ring compressor (2),- a first phase separator (4) fluidly connected to the heat exchanger (3), and a stabilizing column (9) fluidly connected to the first phase separator (4),- wherein at least one of the heat exchanger (3), the first phase separator (4) and the stabilizing column (9) serves as the gas source (40) capable of providing at least one non-condensable gas (6, 11).
11. A method comprising:- providing at least one non-condensable gas (6, 11) obtained from a plastic pyrolysis process,- combusting the at least one non-condensable gas (6, 11) by a thermal oxidizer (41),- guiding a flue gas (50) from the thermal oxidizer (41) to at least one heating space (42) within a muffle (45) of a pyrolysis reactor (17), wherein the pyrolysis reactor (17) is arranged external to and downstream of the thermal oxidizer (41), and - guiding the flue gas out of the at least one heating space (42) without providing a separate oxidation or adsorption system arranged downstream of the muffle (45).
12. The method according to claim 11, wherein the method comprises pressurizing the at least one non-condensable gas (6, 11) by a compressor.
13. The method according to claim 11 or 12, wherein the method comprises combusting the at least one non-condensable gas (6, 11) by the thermal oxidizer (41) in a temperature range between 800 °C and 1200 °C.
14. The method according to any one of claims 11 - 13, wherein the method comprises allowing at least a part of the flue gas (50) to bypass the pyrolysis reactor (17) or the muffle (45) via a bypass piping system (47).
15. The method according to any one of claims 11 - 13, wherein the method comprises injecting air into at least one section of the muffle (45) to control a flue gas temperature and / or mixing air with the flue gas upstream of the muffle (45).
16. The method according to any one of claims 11 - 13, wherein the method comprises recovering heat from the flue gas by a heat recovery system (48) arranged downstream of the pyrolysis reactor (17), arranged downstream of the muffle (45) or arranged downstream of the at least one heating space (42).
17. The method according to claim 16, wherein the method comprises removing contaminants from the flue gas by a scrubbing unit (49) arranged downstream of the heat recovery system (48).
18. The method according to any one of claims 11 - 17, wherein a residence time of the at least one non-condensable gas (6, 11) within a combustion chamber of the thermal oxidizer (41) is greater than 2 seconds.