Systems and methods for removing contaminants from pyrolysis fluids - Patents.com

Abstract

A system for removing contaminants from a pyrolysis fluid is provided. The system comprises a recirculation loop and a bleed-off line. The recirculation loop comprises a quench vessel, a separation device, a recirculation line, and a cooling device. The quench vessel has a first inlet for receiving a supply of pyrolysis fluid, a second inlet configured to receive the recirculation fluid, and an outlet for discharging the quenched pyrolysis fluid. The separation device is for removing contaminants from the quenched pyrolysis fluid to provide a clarified stream, the separation device configured to receive the quenched pyrolysis fluid from the outlet. The recirculation line is configured to receive at least a recirculation portion of the clarified stream and recirculate the recirculation portion to the second inlet. The cooling device is configured to cool the fluid in the recirculation loop. The bleed-off line is for selectively bleeding off a bleed-off portion of the clarified stream from the recirculation loop.

Description

[Background technology]

[0001] As disclosed in WO2021123822, WO2016030460 and WO2011077419, a pyrolysis unit can be used to convert mixed waste plastics into hydrocarbon liquids. The process produces pyrolysis fluids, such as hydrocarbon vapors. These pyrolysis fluids can then be used for further processing. Typically, this further processing may include one or more of a condensation / fractionation column, a knock-out vessel, and / or a direct / direct heat exchanger.

[0002] The mixed waste plastics fed to this process typically contain one or more contaminants. These can include, for example, organic debris, paper, polyamides (such as nylon) and any other gaseous or liquid contaminants, as well as carbonaceous solids. These contaminants can be in the form of multi-component complex asphaltenes, tars and gums. The pyrolysis fluids undergoing further processing may be contaminated with one or more of these contaminants.

[0003] When this pyrolysis fluid containing entrained contaminants undergoes condensation, these contaminants can accumulate in any process equipment, piping, in-line items, instrumentation, and even the liquid product itself. This can cause flow blockages and / or equipment failures, resulting in more frequent required reactive maintenance, reduced plant availability, and reduced product quality.

[0004] Removal of these contaminants is not straightforward as, due to the nature of the mixed plastics as initially fed, they exhibit a range of densities and melting points, both heavier components that solidify and precipitate quickly at high temperatures (approximately 100-160°C) and lighter components that remain viscous / amorphous but remain in suspension throughout the liquid condensation / treatment process. The cohesive / adhesive nature of these contaminants tends to promote coating, layer formation and thereby make them difficult to handle. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there is a need for improved systems and methods for removing contaminants from pyrolysis fluids. [Means for solving the problem]

[0006] A system for removing contaminants from pyrolysis fluids is provided by claim 1. The system allows for effective treatment of the pyrolysis fluids to remove contaminants.

[0007] The system may further comprise a flow control device configured to control the flow through the bleed off line such that the volumetric flow rate through the bleed off line is less than the volumetric flow rate through the recirculation line, meaning that a majority of the clarified fluid is returned to the quench vessel for the quenching process.

[0008] The volumetric flow rate through the bleed off line may be up to 30% of the volumetric flow rate through the recirculation line. Such a level of recirculation can provide effective quenching. Alternatively, the volumetric flow rate through the bleed off line may be up to 20% or 10% of the volumetric flow rate through the recirculation line.

[0009] The flow control device may comprise a valve. Such a valve may effectively control the flow through the bleed-off line.

[0010] The system can further include a controller configured to control a flow control device that controls the flow through the bleed-off line. The controller can be an electrical / electronic controller, a mechanical controller, or a combination of the two.

[0011] The controller can control the flow control device based on one or more of the volumetric flow rate into the separation device or the volume of fluid in the quench vessel or separation device, which measurements allow for effective control of the flow rate around the system.

[0012] The controller can be configured to control the flow control device to control the flow through the bleed off line such that the volumetric flow rate through the recirculation line is substantially constant, which can be within 5%, within 2%, or within 1%, allowing for continuous operation of the system.

[0013] The system may further include a pump configured to pump the quenched pyrolysis fluid from the outlet to the separation device, and the controller is further configured to control the pump. The controller may control the pump such that the volumetric flow rate through the recirculation line is substantially constant. The pump may control the amount of fluid flowing from the quench vessel and thus the flow rate through the system.

[0014] The separation device may further include a filter between the separation device and the recirculation line. Such a filter is an effective way to reduce contaminants in the fluid. There may be multiple filters between the separation device and the recirculation line.

[0015] The bleed off line may further comprise a secondary separation device for filtering the flow through the bleed off line. Filtering the flow through the bleed off line may enable removal of additional pyrolysis oil and / or other contaminants for further processing of the bleed off portion.

[0016] The quench vessel may comprise a condensation column or a quench column. Such columns are particularly useful for treating pyrolysis fluids.

[0017] The separation apparatus may include a decantation vessel, which is an effective way of separating the quenched fluid: the denser components settle to the bottom of the vessel so that the quenched fluid can be separated.

[0018] The decantation vessel may further comprise an outlet, and the separation apparatus may further comprise a return line configured to return the fluid discharged from the outlet to the decantation vessel, which effectively displaces precipitated material within the vessel to reduce the risk of clogging. The outlet may be for removing fluids that are heavier in density than the clarified stream from the decantation vessel, i.e., the outlet may be located lower in the decantation vessel than where the clarified stream is removed.

[0019] The system may further comprise an exhaust flow control device configured to control flow through the exhaust line, and an exhaust controller configured to control operation of the exhaust flow control device based on a contamination level of the supply of pyrolysis fluid, thereby allowing the system to adjust based on contamination of the input feed.

[0020] The system may further include a drain line configured to selectively drain the fluid discharged from the outlet to a secondary decantation vessel, which allows the precipitated material to be extracted from the decantation vessel for further processing. The secondary decantation vessel may remove fluids of different specific gravity compared to the first decantation vessel.

[0021] The secondary decantation vessel may further comprise an outlet, and the secondary decantation vessel may further comprise a return line configured to return fluid discharged from the outlet to the secondary decantation vessel. This effectively displaces precipitated material within the vessel, reducing the risk of clogging. The outlet may be for removing fluids having a higher specific gravity than the wastewater from the decantation vessel. That is, the outlet may be located lower in the decantation vessel than where the wastewater is removed.

[0022] The system may further include a second discharge line configured to selectively discharge the fluid discharged from the outlet to a third separation device configured to receive the discharge fluid for removing solids from the discharge fluid. The third separation device outputs wastewater for removal from the system.

[0023] The bleed-off line may include a third discharge line configured to discharge at least a portion of the bleed-off portion into a secondary decantation vessel to allow for further processing of the bleed-off portion, which portion may be wastewater removed from the bleed-off portion.

[0024] The quench vessel may be configured to receive multiple fluid streams from multiple processes that are out of phase with each other. The system may operate continuously, with new material being inserted as soon as it is produced. Selective use of a bleed off line may then be used to account for the material being added. One or more of the fluid streams may be a recovered pyrolysis oil stream.

[0025] A method for removing contaminants from pyrolysis fluids is provided by claim 20. This method is an effective way of treating pyrolysis fluids to remove contaminants.

[0026] The method may further include controlling the flow to the bleed off line with a flow control device such that the volumetric flow rate through the bleed off line is less than the volumetric flow rate back to the quench vessel, meaning that the majority of the clarified fluid is returned to the quench vessel for the quench process.

[0027] The method may further include operating the processes out of phase with one another and feeding the output of each of the processes as one or more fluid streams to the quench vessel. The system may be run continuously, with new material being inserted as soon as it is produced. Selective use of the bleed off line may then be used to account for the material being added.

[0028] The condensing of the fluid stream, the discharge of the quenched pyrolysis fluid, the separation of the quenched pyrolysis fluid, and the return of the clarified stream may be performed continuously. By performing these elements continuously, the system can easily receive new material as it is produced.

[0029] The quench vessel can operate at temperatures between 40°C and 300°C, which are suitable temperatures for the quenching treatment of pyrolysis fluids derived from mixed plastic waste.

[0030] A portion of the clarified stream may be cooled to below 50° C. Cooling fluid at this temperature can be used to effectively quench the pyrolysis fluids.

[0031] The separation device may be a decantation vessel and the clarified stream may be separated from the quenched pyrolysis fluids by removing fluids having a specific gravity below a threshold value, which is an effective method for separating the clarified stream from heavier material contaminants.

[0032] The threshold value may be 0.9, which separates the pyrolysis oil stream from heavier contaminants.

[0033] The method can further include continuously discharging fluid from a lower portion of the decantation vessel and returning the fluid to the decantation vessel, the continuous recirculation of the flow helping to prevent blockages due to accumulation of solids.

[0034] The method may further include removing fluids having a specific gravity greater than a threshold value from the decantation vessel and separating the removed fluids and removing wastewater therefrom using a secondary decantation vessel, the secondary decantation vessel allowing for separation of additional fluids, such as wastewater accumulated from a previous process.

[0035] The method can further include continuously discharging fluid from a lower portion of the secondary decantation vessel and returning the fluid to the decantation vessel. This continuous recirculation of the flow helps prevent blockages due to accumulation of solids.

[0036] This disclosure refers to the accompanying drawings. [Brief description of the drawings]

[0037] [Figure 1] 1 shows a system for removing contaminants from a pyrolysis fluid according to a first embodiment. [Diagram 2] 3 shows a system for removing contaminants from pyrolysis fluids according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Figures 1 and 2 each show an embodiment of a system for removing contaminants from a pyrolysis fluid. Any features disclosed in connection with one embodiment are equally applicable to other embodiments, unless expressly stated otherwise. Each of Figures 1 and 2 shows a specific arrangement for a given purpose. It is understood that the present disclosure may be applied to any suitable process, and that unless otherwise stated, each element of the system shown in Figures 1 and 2 may be included or excluded within the scope of the claims as appropriate.

[0039] FIG. 1 shows a system 100 for removing contaminants from pyrolysis fluids. The system 100 includes a quench vessel 10, which may be a condensation or quench column. The quench vessel 10 is used to quench an input feed of pyrolysis fluid. A first inlet 1 to the quench vessel 10 is provided. The pyrolysis fluid is delivered to the quench vessel 10 through this first inlet 1. As also shown in FIG. 1, one or more additional fluids may be fed to the quench vessel. They may each be through their own separate inlet 1 or through a combined first inlet 1. The quench vessel 10 may be fed with one or more of the following: recovered pyrolysis oil, water wash column surface water discharge, and pyrolysis steam. The pyrolysis fluid may be supersaturated pyrolysis steam, such as that coming from one or more waste plastic pyrolysis units. The pyrolysis fluids typically contain numerous gaseous and / or liquid contaminants (e.g., in the form of multicomponent complex asphaltenes, tars and gums) as well as carbonaceous solids produced in the upstream pyrolysis unit. Thus, although the term "fluids" is used throughout this specification, it is understood to include gases, liquids and / or entrained solids.

[0040] The pyrolysis fluid may be sourced from a pyrolysis system that pyrolyzes mixed plastic waste, which typically contains a variety of contaminants that become part of the pyrolysis fluid.

[0041] The quench vessel 10 further comprises an outlet 12 for discharging the quenched pyrolysis fluid therefrom. As shown in FIG. 1, this outlet 12 may be at the bottom of the pyrolysis vessel 10 in use. The quench vessel 10 may operate at 40° C.-300° C. in use to condense the condensable components of the pyrolysis fluid. The non-condensed pyrolysis vapors may exit the quench vessel via a second outlet 13. Generally, this second outlet 13 may be for non-condensables. As shown in FIG. 1, this second outlet 13 may be at the top of the quench vessel 10. This pyrolysis vapor may then undergo further downstream processing. For example, the pyrolysis vapor may be treated in a wash column system to remove residual hydrocarbons, thereby forming and cleaning gas. Water discharged from this wash column system may be returned to the quench vessel 10.

[0042] The quench vessel 10 can take any suitable form and configuration. For example, in certain embodiments, the quench vessel 10 can include an internal loose and / or fixed bed packing that has a high fouling resistance. This allows for an increase in the energy transfer area and thus minimizing the overall size of the physical equipment. However, in alternative forms, such packing may be omitted to reduce the frequency of required maintenance.

[0043] The vessel outlet 12 is for discharging the quenched pyrolysis fluid, which may be pyrolysis oil. In certain examples, the quench vessel 10 may include a cone-shaped bottom head to facilitate transfer out of the quench vessel 10 via the outlet 12.

[0044] Downstream of the outlet 12 of the quench vessel 10 is a separation device. The separation device may be a single component or may be formed from one or more separate elements. The separation device may comprise a decantation vessel 21, such as a settling vessel. Alternatively or additionally, the separation device may comprise a filter 27. The separation device is configured to receive the quenched pyrolysis fluid from the outlet 12 of the quench vessel 10. The separation device is suitable for removing contaminants from the quenched pyrolysis fluid to provide a clarified (or filtered) stream. This clarified stream can then be subjected to further processing.

[0045] A quench pump 18 may be provided for moving the quenched pyrolysis fluid from the quench vessel 10 to the separation system.

[0046] In a particular example, the separation device is a decantation vessel 21. Such a decantation vessel 21 may be configured to separate the quenched pyrolysis fluid. For example, the decantation vessel 21 may separate the quenched pyrolysis fluid into clarified pyrolysis oil as a clarified stream, water, and heavy solids such as asphaltenes, tar, and pyrolysis coke as waste products.

[0047] The clarified stream may overflow from the decantation vessel 21 via outlet 22 for further processing. In certain embodiments, a suction vessel and / or pump 23 may be provided to extract the clarified stream from the decantation vessel 21. The pump 23 may be a low net positive suction head pump 23 that may avoid the need to use a suction vessel. Alternatively or additionally, the relative height of the decantation vessel 21 and any associated piping may be such as to meet any requirements of the pump 23.

[0048] The decantation vessel 21 may be configured such that water and solid material with a specific gravity above 0.9 settles to the bottom of the decantation vessel 21. That is, the decantation vessel 21 may be designed to allow fluids and solids with a specific gravity above 0.9 to settle to the bottom of the vessel. Preferably, the decantation vessel 21 has a conical shape at its lower part to improve the ease of removal of this material. The clarified pyrolysis oil, having a lower specific gravity, remains at the top of the decantation vessel 21 and is removed therefrom as a clarified stream.

[0049] The precipitated material can be removed from the decantation vessel 21 via the outlet 24. The outlet 24 can be connected to a return line 26 configured to return the fluid removed via the outlet 24 to the decantation vessel 21. The fluid can be, for example, a mixture of water and heavy solids, including some entrained pyrolysis oil. A pump 28, such as a pneumatic diaphragm pump, can be configured to drive the fluid through the return line 26. The pump 28 can be operated continuously to ensure a continuous flow through the return line 26. The flow can be a low-speed flow. The exact flow rate and speed are selected based on the parameters of the system. In a particular example, the flow through the return line 26 can have a speed of less than 1 meter per second. This flow is suitable to keep the return line 26 and the nozzles therein clean while avoiding mixing of solids and liquids in the decantation vessel 21. This continuous flow can help prevent blockages in the decantation vessel 21 due to accumulation of solids. The pump 28 is preferably a pneumatic diaphragm pump. Such a pump 28 typically requires less maintenance time for servicing, which is particularly beneficial given its purpose in the system 100 and the high risk of exposure to adherent solid contamination.

[0050] The system 100 may further comprise a first discharge line 25 configured to selectively discharge fluid from the decantation vessel 21 for further processing, as described below. That is, the first discharge line 25 may remove material from the return line 26 so that it does not return to the decantation vessel 21. The flow through the first discharge line 25 may be controlled by a discharge flow controller 29, which may include, for example, a valve. The discharge flow controller 29 may control the flow through the first discharge line 25. That is, the discharge flow controller 29 may selectively (partially or completely) inhibit the flow through the first discharge line 25.

[0051] In certain embodiments, the discharge flow control device 29 can be controlled by a discharge controller to periodically remove material from the return line 26. This discharge controller can include a timer in some forms. The timer can be electronic or mechanical. The discharge controller can be preferentially adjusted to accommodate anticipated increases in solids loading that may occur if contamination of the mixed waste plastic feedstock increases. For example, if a more contaminated system is fed with material, the discharge controller can be adjusted to change one or more of the frequency of material removal and / or the length of time that the flow control device 29 allows material removal. That is, the discharge controller is configured to control the operation of the discharge flow control device 29 based on the contamination level of the pyrolysis fluid feed to the quench vessel 10.

[0052] Material in the separation device that does not form part of the clarified stream may be subjected to further processing steps, as described in more detail below.

[0053] One or more filters 27 may be provided as part of the separation apparatus. In certain instances, the decantation vessel 21 may not be present and the separation apparatus may simply be one or more filters 27. In further instances, the quench vessel 10 and the decantation vessel 21 may be combined. The filter 27 may be any suitable filter type. This may include, for example, a cartridge type filter. However, multiple filter types are suitable and may be specified according to operator preference. This filter 27 may be configured to further filter and purify the clarified stream. For example, the filter 27 may be configured to reduce the particle load to less than 100 parts per million. In further embodiments, there may be a stepped series of filters 27, each configured to reduce the particle load to a lower level. For example, one filter 27 may be configured to reduce the particle load to less than 50 parts per million, followed by the next filter 27 configured to reduce the particle load to less than 10 parts per million.

[0054] A cooling device 30 is further provided in the system 100. Although in FIG. 1 the cooling device is shown between the decantation vessel 21 and the filter 27 (and thus in the assembly element designated as a separation device), this is not a requirement. Indeed, the cooling device 30 may be provided at any suitable location in the system 100 for cooling fluids therein. In use, the cooling device 30 may receive a fluid, such as a clarified stream, having a temperature as high as 300° C. The cooling device 30 may be configured to cool the received fluid to below 50° C.

[0055] In certain embodiments, the cooling device 30 may be a heat exchanger. However, any suitable cooling device 30 is contemplated. Such a heat exchanger may be selected to increase resistance to fouling. It may be a spiral-type heat exchanger. Such a spiral-type heat exchanger may be readily available to help avoid fouling. The effect of the cooling device 30 is to provide a chilled fluid. This may be a chilled and clarified fluid, for example, if the cooling device 30 is downstream of one or more components of a separation device.

[0056] The system 100 further comprises a recirculation line 40. The recirculation line 40 is configured to receive at least a portion of the clarified stream. The portion of the clarified stream received by the recirculation line 40 is designated as the recirculation portion. This recirculation portion of the clarified stream is then returned to the quench vessel 10 via the second inlet 14 of the quench vessel 10. Thus, the recirculation portion of the clarified fluid is recirculated to the quench vessel 10. This acts as a quench recirculation stream from the quench vessel 10. The second inlet 14 may be located at the top of the quench vessel 10.

[0057] Although the recycle line 40 is shown in a particular location in FIG. 1, it will be understood that it may be located at any suitable location within the system 100 so long as the recycle portion can be returned to the quench vessel 10.

[0058] Collectively, the quench vessel 10, the separator and the recirculation line 40 define a recirculation loop which serves to quench an input pyrolysis fluid, separate contaminants therefrom to produce a clarified stream, and return at least a portion of the clarified stream to the quench vessel 10. A cooling device 30 is positioned within the recirculation loop to cool the fluid flowing therethrough.

[0059] The system 100 further comprises a bleed-off line 50 for selectively bleeding off at least a portion of the clarified stream from the recirculation loop, referred to as the bleed-off portion. As shown in FIG. 1, the bleed-off line 50 and the recirculation line 40 may be separated from each other at a three-way junction to which the clarified fluid is fed. Thus, the bleed-off portion and the recirculation portion may be combined into a total clarified stream.

[0060] The system 100 may further comprise a flow control device 60 configured to control the flow through the bleed off line 50. That is, the flow control device 60 may selectively (partially or completely) inhibit the flow through the bleed off line 50. The flow control device 60 may be any suitable device, and may include, for example, a valve and / or a flow restrictor. The flow control device 60 may be configured to control the flow through the bleed off line 50 based on a volumetric flow rate (also known as a volumetric flow rate) of the fluid through the system 100. In particular, the flow control device 60 may control the flow through the bleed off line 50 such that the volumetric flow rate of the fluid through the bleed off line 50 is less than the volumetric flow rate of the fluid through the recirculation line 40. That is, the bleed-off portion of the clarified stream may be less than the recirculation portion of the clarified stream. In certain examples, the volumetric flow rate through the bleed off line 50 may be up to 30%, 20%, or 10% of the volumetric flow rate through the recirculation line 40.

[0061] The system 100 may further comprise a controller configured to control the flow control device 60. The controller may be an electrical / electronic controller, such as a processor. Alternatively, the controller may be purely mechanical, such as based on mechanical flow sensors and switches. A combination of electrical / electronic and mechanical controllers is also possible.

[0062] The controller may control the flow control device 60 based on other conditions of the system 100. For example, the controller may be configured to determine the volume of fluid in the quench vessel 10 and / or the separation device, in particular the decantation vessel 21. Alternatively or additionally, the controller may be configured to determine the volumetric flow rate of fluid through any part of the system 100, for example to the separation device or from the quench vessel 10. This may in particular be the volumetric flow rate to the decantation vessel 21. The flow control device 60 may be controlled by the controller to adjust the volume and / or the volumetric flow rate of the bleed-off portion based on these measured conditions. The measurements may be based on digital sensors and signals, but equally this may be achieved purely mechanically via float switches and / or mechanical flow sensors, etc.

[0063] In certain embodiments, the flow controller 60 may be configured to drain excess level from the decantation vessel 21 when mass is introduced into the system 100 in the quench vessel 10 via the first inlet 1. As mass is introduced into the system 100, the level in the decantation vessel 21 rises and when it reaches a threshold value, the flow controller 60 controls the flow through the bleed off line 50 to bleed off any additional product. Thus, the normal flow rate of fluid through the recirculation line 40 is maintained.

[0064] To maintain a nearly constant flow rate of fluid through the recirculation line 40, the flow control device 60 can control the flow through the bleed off line 50 such that the volumetric flow rate through the recirculation line 40 (i.e., that which is not bled off via the bleed off line 50) is substantially constant. In this context, substantially constant can mean that the flow rate does not vary by more than 5%, preferably by more than 2%, and most preferably by more than 1%.

[0065] The controller may further control the operation of the quench pump 18 and / or the suction vessel and / or the pump 23 to maintain this approximately constant flow rate, and therefore volume, in the recirculation loop.

[0066] The bleed-off line 50 may include further processing for the bleed-off portion of the fluid. For example, this may include a secondary separation device. At the simplest level, this may be in the form of one or more additional filters 57. These additional filters 57 may be of any suitable type, such as cartridge filters. In certain examples, these filters 57 may be arranged in a stepped series of filters 57, each arranged to reduce the particle load to a lower level. For example, one filter 57 may be arranged to reduce the particle load to less than 50 parts per million, and then the next filter 57 may be arranged to reduce the particle load to less than 10 parts per million. In FIG. 1, the flow control device 60 is shown between the two filters 57, but it is understood that this is not necessarily the case and the flow control device 60 may be located in any suitable location.

[0067] The secondary separation device may further include a water separation system 80, which may include a cartridge water coalescer and / or a two-phase liquid-liquid separator and / or any other water separation device. The water separation system 80 may be configured to reduce the free water concentration in the bleed-off portion.

[0068] The pyrolysis oil may be extracted from the secondary separation device for transport to a downstream system. This pyrolysis oil may be reintroduced into the system 100, for example into a separation device such as the decantation vessel 21 or into the quench vessel 10. Where the pyrolysis oil is reintroduced may depend on the solids content of the pyrolysis oil. For example, if the solids content of the recovered pyrolysis oil is less than (or equal to) a threshold value, it may be introduced into the quench vessel 10. If the solids content of the recovered pyrolysis oil is greater than the threshold value, it may be reintroduced into a separation device, in particular the decantation vessel 21.

[0069] The secondary separation apparatus may discharge waste liquid via a second discharge line 85. The second discharge line 85 may discharge this waste liquid to any suitable further apparatus and / or process, including waste. The specific further treatment system for this second discharge line 85 is described in more detail below. The second discharge line 85 may generally discharge accumulated waste water from the secondary separation apparatus, particularly if a water separation system 80 is included in the secondary separation apparatus. The waste liquid discharged via the second discharge line 85 may be designated as part of the bleed-off portion.

[0070] The flow through the second exhaust line 85 may be controlled via an exhaust flow controller 89, which may include, for example, a valve. In particular, the exhaust flow controller 89 may be configured to operate in a control loop to maintain a volume of fluid within the water separation system 80. Such control may include one or more electronic components. Alternatively, this control may be achieved purely mechanically or as a mixture of electronic and mechanical control.

[0071] As discussed above, decantation vessel 21 includes a first discharge line 25 that can discharge fluids therein to a secondary decantation vessel 71. This secondary decantation vessel 71 may be generally as described above with respect to decantation vessel 21. This secondary decantation vessel 71 may be configured to separate water and residual hydrocarbons from heavier solids. The secondary decantation vessel 71 may be designed to allow fluids and solids with a specific gravity greater than 1 to settle to the bottom of the vessel.

[0072] An outlet 72 of the secondary decantation vessel 71 may be provided for fluid to overflow from the secondary decantation vessel 71 in. In particular, this may be wastewater containing residual pyrolysis oil. This flow may or may not be pumped, depending on the specific requirements of the system. The wastewater may undergo further treatment, such as a wastewater treatment plant or a downstream wastewater bulk vessel or tank. In some examples, the system 100 may be equipped with oil recovery equipment so that the pyrolysis oil can be recovered and returned to the quench vessel 10 and / or the separation device (in particular the decantation vessel 21). This may help to reduce yield losses. Where the pyrolysis oil is reintroduced may depend on the solids content of the pyrolysis oil. For example, if the solids content of the recovered pyrolysis oil is less than (or equal to) a threshold value, it may be introduced into the quench vessel 10. If the solids content of the recovered pyrolysis oil is greater than the threshold value, it may be reintroduced into the separation device, in particular the decantation vessel 21.

[0073] The secondary decantation vessel 71 may further be supplied with material discharged from the secondary separation device via a second discharge line 85. In particular, this may be an accumulation of wastewater from the water separation system 80.

[0074] At the lower end of the secondary decantation vessel 71 there is a return arrangement substantially similar to that described with respect to the decantation vessel 21.

[0075] The precipitated material may be removed from the secondary decantation vessel 71 via the outlet 74. The outlet 74 may be connected to a return line 76 configured to return the fluid removed via the outlet 74 to the secondary decantation vessel 71. The fluid may be, for example, a mixture of water and heavy solids, including some entrained pyrolysis oil. A pump 78, such as a pneumatic diaphragm pump, may be configured to drive the fluid through the return line 76. The pump 78 may be operated continuously to ensure a continuous flow through the return line 76. The flow may be a low-velocity flow. The exact flow rate and velocity are selected based on the parameters of the system. In a particular example, the flow through the return line 76 may have a velocity of less than 1 meter per second. This flow is suitable to keep the return line 76 and the nozzles therein clean while avoiding mixing of solids and liquids in the decantation vessel 71. This continuous flow may help prevent blockages in the secondary decantation vessel 71 due to solids accumulation. The pump 78 is preferably a pneumatic diaphragm pump. Such a pump 78 typically requires less maintenance time for servicing, which is particularly beneficial given its purpose in the system 100 and the high risk of exposure to adherent solid contamination.

[0076] The system 100 may further comprise a third drain line 75 configured to selectively drain fluid from the secondary decantation vessel 71 for further processing, as described below. The flow through the third drain line 75 may be referred to as drain fluid. That is, the third drain line 75 may remove material from the return line 76 such that the material does not return to the secondary decantation vessel 71. The flow through the third drain line 75 may be controlled by a drain flow controller 79, which may include, for example, a valve. The drain flow controller 79 may control the flow through the third drain line 75. That is, the drain flow controller 79 may selectively (partially or completely) inhibit the flow through the third drain line 75.

[0077] In certain embodiments, the discharge flow control device 79 can be controlled by a discharge controller to periodically remove material from the return line 76. This discharge controller can, in some forms, include a timer. The timer may be electronic or mechanical. The discharge controller can be preferentially adjusted to accommodate anticipated increases in solids loading that may occur if contamination of the mixed waste plastic feedstock increases. For example, if material is fed into a more contaminated system, the discharge controller can be adjusted to change one or more of the frequency of material removal and / or the length of time that the flow control device 29 allows material removal.

[0078] The third discharge line 75 may be connected to a third separation device, such as a dewatering device 90. This may be, for example, a dewatering vessel, which may be a mobile vessel. The dewatering vessel 90 may be combined with an internal filter membrane or media. This dewatering vessel 90 may be configured to separate heavy solids from the water in the discharge line 75. In this sense, the dewatering vessel 90 removes solids from the discharge fluid of the third discharge line 75. The dewatering vessel 90 may be sized to minimize the frequency of emptying to suit the operator's preferences. For example, the dewatering vessel 90 may be 1 cubic meter to 35 cubic meters. Alternatively or additionally, the dewatering vessel 90 may be limited in size to fit local truck collection capabilities. This allows the dewatering vessel 90 to be removed for onward transport to the heavy product end user.

[0079] A dewatering pump 98 may be provided to move the wastewater from the dewatering vessel 90. The wastewater may undergo further processing, such as in a wastewater treatment plant or a downstream wastewater bulk vessel or tank. In some examples, the system 100 may include oil recovery equipment so that the pyrolysis oil may be recovered and returned to the quenching vessel 10 and / or the separation device (particularly the decantation vessel 21). This may help to reduce yield losses. Where the pyrolysis oil is reintroduced may depend on the solids content of the pyrolysis oil. For example, if the solids content of the recovered pyrolysis oil is less than (or equal to) a threshold value, it may be reintroduced to the quenching vessel 10. If the solids content of the recovered pyrolysis oil is greater than the threshold value, it may be reintroduced to the separation device, particularly the decantation vessel 21.

[0080] As mentioned above, the system 100 shown in Figure 1 is merely one example of the present disclosure, and any feature of the system 100 may be used alone, if desired.

[0081] Reference is now made to Figure 2, which shows a further system 100 for removing contaminants from pyrolysis fluids. The system 100 of Figure 2 is substantially identical to that shown in Figure 1 and described above, unless otherwise indicated. In particular, any disclosure above in relation to Figure 1 may be equally applied and / or combined with the disclosure of Figure 2.

[0082] Specifically, but without limitation, the quench vessel 10, separation equipment (including decantation vessel 21), cooling equipment 30, recirculation line 40, bleed off line 50, flow control device 60, secondary decantation vessel 71, water separation system 80 and dewatering equipment 90, along with their associated components, may be generally as described above.

[0083] The secondary separation device of system 100 may further include a wash water column 81, as shown in Figure 2, which may be configured to mix the incoming bleed-off portion of the clarified stream with water, which may be tap water and / or deionized water, as desired. This mixing may remove precipitate from the bleed-off portion, for example to a level of less than 10 parts per million.

[0084] Preferably, the bleed-off portion enters through the lower portion of the wash column 81. Wash water is preferably fed to the upper portion of the wash column 81. The wash column 81 may include loose or fixed bed packing. Such packing promotes washing efficiency, thereby allowing the physical dimensions of the wash column 81 to be reduced for the same amount of sediment removal. The wash column 81 may also include an internal flow distribution component. The wash column 81 may also include a coalescing pad, which may act to promote separation of water droplets from the bleed-off portion of the clarified stream.

[0085] The flow of wash water to the wash column 81 can be controlled via the wash column flow controller 60a. In particular, the volumetric flow rate of wash water to the wash column 81 may be based on the volumetric flow rate of the bleed-off portion of the clarified stream to the wash column 81. This may be proportional based on a ratio. This ratio between the two fluids may be adjustable to accommodate expected increases in solids loading that may occur in the event of increased contamination of the mixed waste plastic feedstock. Again, this control may be electrical / electronic, mechanical, or a mix of both.

[0086] The washing column 81 may further comprise a washing column discharge line 85a for removing waste water from the washing column 81. This washing column discharge line 85a may be located at the bottom of the washing column 81. The flow through this washing column discharge line 85a may be selectively controlled by a washing column discharge flow controller 89a. In particular, the washing column discharge flow controller 89a may control the flow through the washing column discharge line 85a based on the level of the bleed-off portion of the clarified stream in the washing column 81, in particular the level of pyrolysis oil in the washing column 81. That is, the washing column flow controller 89a may selectively (partially or completely) inhibit the flow through the washing column discharge line 85a. The level of the bleed-off portion of the clarified stream in the washing column 81 may be measured using any suitable means, again the control may be electrical / electronic, mechanical, or a mixture of both.

[0087] The wash column discharge line 85a may discharge into a secondary decantation vessel 71 for treatment as described above in connection with FIG.

[0088] A washed bleed-off portion of the clarified stream is extracted from the wash column 81, e.g., via a top outlet, and then passed on for further processing as described above in relation to Figure 1. In particular, this washed bleed-off portion may be transferred to the water separation system 80, as described above. This may be via a filter 57a configured to reduce the particle loading of the washed bleed-off portion, e.g., to less than 10 parts per million. The filter 57 may be any type of filter, but is preferably a cartridge-type filter.

[0089] The quench vessel 10 may be configured to receive multiple fluid streams from multiple processes with different phase duty cycles. The supply of pyrolysis fluid received through the first inlet 1 of the quench vessel 10 may be one of these fluid streams; i.e. processes that may finish at different times. In particular, the system 100 may generally be operated continuously; i.e. there may be a continuous flow of fluid through the recycle loop. As material is added to the quench vessel 10, the bleed off line 50 may be selectively used to account for this increased fluid. This means that the volume of material in the recycle loop may generally be maintained. Each fluid stream may be a recovered pyrolysis oil stream.

[0090] In such a system 100, it may be necessary to effectively "prime" the recirculation loop; that is, there may need to be a quantity of fluid already circulating in the loop before the pyrolysis fluid is introduced. Thus, the pyrolysis fluid displaces existing fluid in the primed system 100 through the bleed off line 50 and separation devices described above.

[0091] A method for removing contaminants from pyrolysis fluids is also provided, which may optionally utilize any of the devices described above in Figures 1 and 2.

[0092] The method includes providing a pyrolyzed fluid to a quench vessel 10. The pyrolyzed fluid is then quenched in the quench vessel 10 to form a quenched pyrolyzed fluid. The method then includes discharging the quenched pyrolyzed fluid from the quench vessel to a separation apparatus. The quench vessel 10 may operate at between 40°C and 300°C.

[0093] The separation device may be any of the separation devices described above, in particular the decantation vessel 21. When the separation device is the decantation vessel 21, the clarified stream is separated from the quenched pyrolysis fluids by removing fluids with a specific gravity below a threshold value. This threshold value may be selected based on the desired composition of the clarified stream. For example, the threshold value may be 0.9.

[0094] The separator separates the quenched pyrolysis fluid to produce a clarified stream. The method then further includes selectively bleeding off a bleed-off portion of the clarified stream via a bleed-off line 50. The clarified stream is cooled in a cooling device 30 to produce a cooled clarified stream. The cooled clarified stream may be cooled to less than 50° C. At least a recycle portion of the clarified stream is returned to the quench vessel 10 via a recycle line 40.

[0095] The flow controller 60 may control the flow to the bleed off line 50 such that the volumetric flow rate through the bleed off line 50 is less than the volumetric flow rate back to the quench vessel 10 .

[0096] Multiple processes may be operated in a heterophase duty cycle, which may be, for example, a heterophase pyrolysis unit, and the output from each of these processes may then be fed as one or more fluid streams to the quench vessel 10.

[0097] The system 100, and in particular the recirculation loop, may be operated continuously, which may mean, for example, that the condensation of the fluid stream, the discharge of the quenched pyrolysis fluid, the separation of the quenched pyrolysis fluid, and the return of the clarified stream are performed continuously.

[0098] The method may include continuously discharging fluid from a lower portion of the decantation vessel 21 and returning the fluid to the decantation vessel 21. This circulates the fluid around the vessel 21, thereby preventing material from building up within the vessel and clogging it.

[0099] Fluids of greater than a threshold specific gravity may be removed from decantation vessel 21 and transported to a secondary decantation vessel 71 as described above. This secondary decantation vessel 71 may then be used to separate wastewater from the removed fluids, also as described above.

[0100] This secondary decantation vessel 71, like the first decantation vessel 21, may include circulation to prevent clogging. This involves continuously discharging fluid from a lower portion of the secondary decantation vessel 71 and returning the fluid to the decantation vessel 71.

[0101] The method may include priming the quench vessel 10 by filling it with a predetermined amount of fluid, such as water. The priming fluid is then displaced and removed by the described method steps as the pyrolysis fluid is introduced into the quench vessel 10.

[0102] As mentioned above, any of these method steps may be used with any of the above-described systems 100. Likewise, the method may be used with any other system 100.

Claims

1. 1. A system for removing contaminants from a pyrolysis fluid, comprising: a recirculation loop, the recirculation loop comprising:

1. A quench vessel comprising: a first inlet for receiving a supply of pyrolysis fluid; a second inlet configured to receive a recirculating fluid; an outlet for discharging the quenched pyrolysis fluid; a quench vessel having a separation device for removing contaminants from the quenched pyrolysis fluid to provide a clarified stream, the separation device being configured to receive the quenched pyrolysis fluid from the outlet; and a recirculation line configured to receive at least a recirculation portion of the clarified stream and recirculate the recirculation portion to the second inlet; a cooling device configured to cool a fluid in the recirculation loop; The system comprises: a bleed-off line for selectively bleeding off a bleed-off portion of said clarified stream from said recirculation loop; A system comprising:

2. 13. The system of claim 1, further comprising a flow control device configured to control flow through the bleed off line such that a volumetric flow rate through the bleed off line is less than a volumetric flow rate through the recirculation line.

3. 3. The system of claim 2, wherein the volumetric flow rate through the bleed off line is up to 30% of the volumetric flow rate through the recirculation line.

4. The system of any of claims 2-3, further comprising a controller configured to control the flow control device to control flow through the bleed-off line.

5. The controller: the volumetric flow rate into the separation device; or The system of claim 4 , further comprising controlling the flow control device based on one or more of a volume of fluid in the quench vessel or the separation device.

6. 6. The system of claim 4 or 5, wherein the controller is configured to control the flow control device to control flow through the bleed off line such that the volumetric flow rate through the recirculation line is substantially constant.

7. The system of any one of claims 4 to 6, further comprising a pump configured to pump the quenched pyrolysis fluid from the outlet to the separation device, the controller further configured to control the pump.

8. The system of claim 7 , wherein the controller is configured to control the pump such that the volumetric flow rate through the recirculation line is substantially constant.

9. 2. The system of any preceding claim, wherein the separation device further comprises a filter between the separation device and the recirculation line.

10. 2. The system of any preceding claim, wherein the bleed off line further comprises a secondary separation device for filtering flow through the bleed off line.

11. 2. The system of any preceding claim, wherein the quench vessel comprises a quench column.

12. 2. The system of any preceding claim, wherein the separation device comprises a decantation vessel.

13. 13. The system of claim 12, wherein the decantation vessel comprises an outlet, and the separation device further comprises a return line configured to return fluid discharged from the outlet to the decantation vessel.

14. 14. The system of claim 13, further comprising a drain line configured to selectively drain fluid discharged from the outlet to a secondary decantation vessel for removing wastewater.

15. an exhaust flow control device configured to control flow through the exhaust line; an exhaust controller configured to control operation of the exhaust flow control device based on a contamination level of the supply of pyrolysis fluid; The system of claim 14 further comprising:

16. 16. The system of claim 14 or 15, wherein the secondary decantation vessel further comprises an outlet, the secondary decantation vessel further comprising a return line configured to return fluid discharged from the outlet to the secondary decantation vessel.

17. 17. The system of claim 16, further comprising a second discharge line configured to selectively discharge fluid discharged from the outlet of the secondary decantation vessel to a third separation device configured to receive the discharge fluid for removing solids from the discharge fluid.

18. The system of any of claims 14 to 17, wherein the bleed-off line comprises a third discharge line configured to discharge at least a portion of the bleed-off portion into the secondary decantation vessel apparatus.

19. 13. A system as claimed in any preceding claim, wherein the quench vessel is configured to receive a plurality of fluid streams from a plurality of processes in phase with one another, preferably one or more of the fluid streams being a recovered pyrolysis oil stream.

20. 1. A method for removing contaminants from a pyrolysis fluid, comprising: providing the pyrolysis fluid to a quench vessel; quenching the pyrolyzed fluid in the quench vessel to form a quenched pyrolyzed fluid; Discharging the quenched pyrolysis fluid from the quench vessel to a separation device; separating the quenched pyrolysis fluid with the separation device to produce a clarified stream; selectively bleeding off a bleed-off portion of the clarified stream via a bleed-off line; cooling at least a portion of the clarified stream in a cooling device to produce a cooled clarified stream; returning at least a recycle portion of the clarified stream to the quench vessel via a recycle line; A method comprising:

21. 21. The method of claim 20, further comprising controlling flow to the bleed off line with a flow control device such that the volumetric flow rate through the bleed off line is less than the volumetric flow rate back to the quench vessel.

22. Running a plurality of processes in different phases; providing an output of each of said processes as said one or more fluid streams to said quench vessel; 22. The method of claim 20 or 21, further comprising:

23. 23. The method of any of claims 20 to 22, wherein condensing the fluid stream, discharging the quenched pyrolysis fluid, separating the quenched pyrolysis fluid and returning the clarified stream are performed continuously.

24. The method according to any of claims 20 to 23, wherein the quench vessel operates at between 40°C and 300°C.

25. The method of any of claims 20 to 24, wherein the portion of the clarified stream is cooled to below 50°C.

26. 26. The method of any of claims 20 to 25, wherein the separation device is a decantation vessel and the clarified stream is separated from the quenched pyrolysis fluids by decanting fluids of a specific gravity below a threshold value from the decantation vessel as the clarified stream.

27. 27. The method of claim 26, wherein the threshold is 0.

9.

28. 28. The method of claim 26 or 27, further comprising continuously discharging fluid from a lower portion of the decantation vessel and returning said fluid to the decantation vessel.

29. removing fluid having a specific gravity greater than the threshold from the decantation vessel; separating the removed fluid using a secondary decantation vessel to remove wastewater therefrom; The method of any one of claims 26 to 28, further comprising:

30. 30. The method of claim 29, further comprising continuously discharging fluid from a lower portion of the secondary decantation vessel and returning the fluid to the decantation vessel.

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