Patent Application
20240158705
This application claims priority to Korean Patent Application No. 10-2022-0151305, filed Nov. 14, 2022, the disclosure of which is hereby incorporated by reference in its entirety.
The present disclosure relates to a method and device for refining waste plastic pyrolysis oil.
Waste plastics, which are produced using petroleum as a feedstock, are difficult to recycle and are mostly disposed of as garbage. These wastes take a long time to degrade in nature, which causes contamination of the soil and serious environmental pollution. As plastic decomposes by exposure to sunlight and heat, the plastic waste releases greenhouse gases such as methane and ethylene. Incineration of plastic waste releases significant amounts of greenhouse gases (GHG), such as carbon dioxide, nitrous oxide and/or methane, into the environment. Carbon dioxide is the primary greenhouse gas contributing to climate change.
As a method for recycling waste plastics, there is a method for pyrolyzing waste plastics and converting the pyrolyzed waste plastics into usable oil, and the obtained oil is called waste plastic pyrolysis oil.
However, pyrolysis oil obtained by pyrolyzing waste plastics cannot be directly used as a high-value-added fuel such as gasoline or diesel oil because it has a higher content of impurities such as chlorine, nitrogen, and metals than oil produced from crude oil by a general method, and therefore, pyrolysis oil needs to go through a post-treatment process.
As a post-treatment process according to the related art, a process of hydrotreating waste plastic pyrolysis oil in the presence of a hydrotreating catalyst to remove impurities such as chlorine, nitrogen, and other metals has been performed. However, in this process, an excessive amount of HCl is produced due to a high content of chlorine contained in the waste plastic pyrolysis oil, which causes equipment corrosion, abnormal reactions, deterioration of product properties, and the like. In particular, HCl reacts with a nitrogen compound to produce an ammonium salt (NH4Cl), and the ammonium salt causes corrosion of a reactor, which causes not only a reduction in durability but also various process problems such as a differential pressure, blockage of a reactor, and a reduction in process efficiency.
Also, since waste plastic pyrolysis oil is a mixture of hydrocarbon oils having various boiling points and various molecular weight distributions, and a composition of impurities in the pyrolysis oil or reaction activity varies depending on the boiling point and molecular weight distribution characteristics of the mixture of hydrocarbon oils, the waste plastic pyrolysis oil cannot be directly used in the petrochemical industry or in the field, and needs to go through a high-value-adding process such as a separation process by boiling point or a lightening process. In the mixture of hydrocarbon oils, olefins, in particular, light olefins such as ethylene and propylene, have been widely used in the petrochemical industry.
A hydrocracking process has been performed as a lightening process to realize high-value-added waste plastic pyrolysis oil. However, waste plastic pyrolysis oil contains an excessive amount of impurities such as chlorine, nitrogen, sulfur, oxygen, and metals compared to crude oil, natural gas, naphtha oil, and the like. Therefore, during the hydrocracking process, reaction activity is significantly reduced due to the impurities, and process efficiency is also reduced because the hydrocracking process is performed separately from the hydrotreating process.
Therefore, there is a need for a technique that may effectively remove impurities in pyrolysis oil and achieve lightening of pyrolysis oil without using a post-treatment process such as hydrotreating or hydrocracking.
An embodiment of the present disclosure is directed to providing a method and device for refining waste plastic pyrolysis oil that may effectively reduce impurities in waste plastic pyrolysis oil, and at the same time, may realize high-value-added pyrolysis oil.
Another embodiment of the present disclosure is directed to providing a method and device for refining waste plastic pyrolysis oil that may implement a stable process without corrosion or blockage of a reactor.
In some embodiments, a method for refining waste plastic pyrolysis oil comprises: (S1) subjecting a waste plastic pyrolysis oil feedstock to a heat treatment by charging the waste plastic pyrolysis oil feedstock into a rotary kiln reactor and increasing a temperature of the rotary kiln reactor to form a product; (S2) recovering a gas component from the product of step (S1); (S3) separating a high boiling point wax component from the recovered gas component and re-supplying the separated high boiling point wax component to the rotary kiln reactor in the step (S1); and (S4) recovering refined oil from the gas component from which the high boiling point wax component has been removed.
In some embodiments, the waste plastic pyrolysis oil feedstock may comprise liquid pyrolysis oil comprising 10 to 30 wt % of Naphtha, 20 to 30 wt % of kerosene (KERO), 10 to 30 wt % of light gas oil (LGO), and 30 to 50 wt % of vacuum gas oil (VGO).
In some embodiments, in step (S1), the heat treatment may be performed by increasing the temperature of the rotary kiln reactor to a third temperature.
In some embodiments, the third temperature may be 400 to 600° C.
In some embodiments, when the temperature of the rotary kiln reactor is increased to the third temperature in step (S1), a temperature increase rate may be 0.5° C./min to 5° C./min.
In some embodiments, the method may further comprise, before the step (S1): (S1-1) subjecting the waste plastic pyrolysis oil feedstock to a first heat treatment by increasing a temperature of the rotary kiln reactor to a first temperature; and (S1-2) subjecting the waste plastic pyrolysis oil feedstock to a second heat treatment by increasing a temperature of the rotary kiln reactor to a second temperature, wherein the temperature of the rotary kiln reactor is increased by sequentially heating the rotary kiln reactor from the first temperature to the third temperature.
In some embodiments, the first temperature may be 50 to 150° C.
In some embodiments, the second temperature may be 220 to 300° C.
In some embodiments, in the step (S1), the heat treatment may be performed by adding an additive.
In some embodiments, the additive may comprise a metal oxide catalyst or a composite catalyst in which an active metal is supported on a metal oxide carrier.
In some embodiments, the method may further comprise, before the step (S1), (S0) charging waste plastics into a pyrolysis reactor and pyrolyzing the waste plastics at a temperature of 300 to 600° C. in a non-oxidizing atmosphere to produce a waste plastic pyrolysis oil feedstock.
In some embodiments, the pyrolysis reactor may comprise a rotary kiln reactor.
In some embodiments, the refined oil recovered in the step (S4) may have a content of chlorine reduced by 50% or more compared to the waste plastic pyrolysis oil feedstock in the step (S1).
In some embodiments, the refined oil recovered in the step (S4) may have a content of each of nitrogen, sulfur, and/or oxygen reduced by 20% or more compared to the content of each of nitrogen, sulfur, and/or oxygen in the waste plastic pyrolysis oil feedstock in the step (S1).
In some embodiments, a weight ratio of the refined oil recovered in the step (S4) to light oil in the waste plastic pyrolysis oil feedstock in the step (S1) may be 1.3 or more.
In some embodiments, a device for refining waste plastic pyrolysis oil comprises: a rotary kiln reactor into which a waste plastic pyrolysis oil feedstock is introduced; a gas separator into which a gas component is introduced from the rotary kiln reactor; a condenser into which a light gas component is introduced from the gas separator; and a re-supply line in which a high boiling point wax component is separated in the gas separator and the separated high boiling point wax component is re-supplied to the rotary kiln reactor.
In some embodiments, the rotary kiln reactor may sequentially comprise a first zone, a second zone, and a third zone in a direction from a feedstock inlet to an outlet.
In some embodiments, the rotary kiln reactor may comprise a batch reactor.
Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.
Unless otherwise defined, all the technical terms and scientific terms used in the present specification have the same meanings as commonly understood by those skilled in the art to which the present disclosure pertains. The description for the known function and configuration unnecessarily obscuring the gist of the present disclosure will be omitted in the following description and the accompanying drawings.
Unless the context clearly indicates otherwise, the singular forms of the terms used in the present specification may be interpreted as including the plural forms. As used herein, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly states otherwise.
For the purposes of this specification, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, dimensions, physical characteristics, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
A numerical range used in the present specification includes upper and lower limits and all values within these limits, increments logically derived from a form and span of a defined range, all double limited values, and all possible combinations of the upper and lower limits in the numerical range defined in different forms. Unless otherwise specifically defined in the present specification, values out of the numerical range that may occur due to experimental errors or rounded values also fall within the defined numerical range. For example, a range of “1 to 10” is intended to include any and all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, all subranges beginning with a minimum value equal to or greater than 1 and ending with a maximum value equal to or less than 10, and all subranges in between, e.g., 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1.
The expression “comprise(s)” described in the present specification is intended to be an open-ended transitional phrase having an equivalent meaning to “include(s)”, “contain(s)”, “have (has)”, or “are (is) characterized by”, and does not exclude elements, materials, or steps, all of which are not further recited herein.
Unless otherwise defined, a unit of “%” mentioned in the present specification refers to “wt %”.
Unless otherwise defined, a unit of “ppm” mentioned in the present specification refers to “mass ppm”.
Unless otherwise defined, a boiling point (bp) mentioned in the present specification refers to a boiling point at 1 atm and 25° C.
Unless otherwise defined, a density mentioned in the present specification refers to a density at 1 atm and 25° C.
Unless otherwise defined, a high boiling point wax component mentioned in the present specification refers to a mixture of hydrocarbons that may exist in a solid state without being dissolved in water during a reaction process or a transfer process.
Unless otherwise defined, impurities mentioned in the present specification comprise chlorine impurities, nitrogen impurities, oxygen impurities, and/or sulfur impurities.
Pyrolysis oil obtained by pyrolyzing waste plastics cannot be directly used as a high-value-added fuel such as gasoline or diesel oil because it has a higher content of impurities such as chlorine, nitrogen, and/or metals than oil produced from crude oil by a general method, and therefore, pyrolysis oil needs to go through a post-treatment process.
As a post-treatment process according to the related art, a process of hydrotreating waste plastic pyrolysis oil in the presence of a hydrotreating catalyst to remove chlorine, nitrogen, and other metal impurities has been performed. However, an excessive amount of HCl is produced due to a high content of chlorine impurities contained in the waste plastic pyrolysis oil, which causes equipment corrosion, abnormal reactions, deterioration of product properties, and the like. In particular, HCl reacts with a nitrogen compound to produce an ammonium salt (NH4Cl), and the ammonium salt causes corrosion of a reactor, which causes not only a reduction in durability but also various process problems such as a differential pressure and a reduction in process efficiency. In addition, a hydrocracking process has been performed as a lightening process to realize high-value-added waste plastic pyrolysis oil. However, as described above, waste plastic pyrolysis oil contains an excessive amount of impurities such as chlorine, nitrogen, and/or metals compared to crude oil, natural gas, naphtha oil, and the like. Therefore, during the hydrocracking process, reaction activity is significantly reduced due to the impurities, and process efficiency is also reduced because the hydrocracking process is performed separately from the hydrotreating process.
In some embodiments, the present disclosure provides a method for refining waste plastic pyrolysis oil, the method comprising: (S1) subjecting a waste plastic pyrolysis oil feedstock to a heat treatment by charging the waste plastic pyrolysis oil feedstock into a rotary kiln reactor and increasing a temperature of the rotary kiln reactor to form a product; (S2) recovering a gas component from a product of step (S1); (S3) separating a high boiling point wax component from the recovered gas component and re-supplying the separated high boiling point wax component to the rotary kiln reactor in the step (S1); and (S4) recovering refined oil from the gas component from which the high boiling point wax component has been removed. Through this, it is possible to effectively remove impurities from waste plastic pyrolysis oil and improve a degree of lightening, such that high-value-added pyrolysis oil may be obtained, and the process may be stably performed without corrosion or blockage of a reactor.
In some embodiments, the step (S1) is a step of subjecting a waste plastic pyrolysis oil feedstock 1 to a heat treatment by charging the waste plastic pyrolysis oil feedstock 1 into a rotary kiln reactor 100 and increasing a temperature of the rotary kiln reactor 100 to form a product. In some embodiments, the waste plastic pyrolysis oil feedstock 1 may be a mixture of liquid hydrocarbon oils produced by pyrolyzing waste plastics in a prior step (S0), which will be described below.
Considering the rotary kiln reactor 100 that performs a reaction through rotation while heating the bottom of the reactor and unique characteristics of liquid pyrolysis oil, impurity removal efficiency and/or lightening efficiency may be significantly improved by using liquid waste plastic pyrolysis oil as a feedstock rather than solid waste plastics.
In some embodiments, the present disclosure relates to a refining method for producing refined oil 10 using waste plastic pyrolysis oil as a feedstock, rather than producing pyrolysis oil using solid waste plastics as a feedstock, and in some embodiments, to a method for refining waste plastic pyrolysis oil having significantly improved impurity removal efficiency and/or lightening efficiency.
In some embodiments, the waste plastic pyrolysis oil feedstock 1 may comprise various impurities in addition to the hydrocarbon oil. For example, the waste plastic pyrolysis oil feedstock 1 may comprise impurities such as at least one of chlorine compound(s), nitrogen compound(s), sulfur compound(s), oxygen compound(s), and/or metal compound(s). In some examples, the waste plastic pyrolysis oil feedstock 1 may comprise 500 ppm or more of nitrogen, 100 ppm or more of chlorine, 30 ppm or more of sulfur, 0.7 wt % or more of oxygen, 20 vol % or more of olefins, and/or 1 vol % or more of conjugated diolefins.
In some embodiments, the mixture of hydrocarbon oils present in the waste plastic pyrolysis oil feedstock 1 may comprise Naphtha having 8 or fewer carbon atoms and a boiling point of 150° C. or lower, KERO having 9 to 17 carbon atoms and a boiling point of 150 to 265° C., LGO having 18 to 20 carbon atoms and a boiling point of 265 to 340° C., and/or VGO having 21 or more carbon atoms and a boiling point of 340° C. or higher in various ranges, but the content of the impurities is merely an example, and a composition of the waste plastic pyrolysis oil is not limited thereto. Typically, the mixture of hydrocarbon oils may comprise an excessive amount of heavy oil such as LGO, VGO, and/or Atmospheric Residue (AR) (bp>540° C.) compared to light oil such as Naphtha or KERO. However, this is merely an example, and the composition of the waste plastic pyrolysis oil feedstock 1 is not limited thereto, and may vary within a range of 100 wt %.
In some embodiments, the waste plastic pyrolysis oil feedstock 1 may be liquid pyrolysis oil comprising 10 to 30 wt % of Naphtha, 20 to 30 wt % of KERO, 10 to 30 wt % of LGO, and/or 30 to 50 wt % of VGO. In some embodiments, the waste plastic pyrolysis oil feedstock 1 may be liquid pyrolysis oil comprising 10 to 30 wt % of Naphtha having 8 or fewer carbon atoms and a boiling point of 150° C. or lower, 20 to 30 wt % of KERO having 9 to 17 carbon atoms and a boiling point of 150 to 265° C., 10 to 30 wt % of LGO having 18 to 20 carbon atoms and a boiling point of 265 to 340° C., and/or 30 to 50 wt % of VGO having 21 or more carbon atoms and a boiling point of 340° C. or higher. Using liquid pyrolysis oil that satisfies the above composition ratio may be advantageous because the impurity removal efficiency and lightening efficiency are improved.
Hereinafter, the method and device for refining waste plastic pyrolysis oil will be described generally with reference to
In some embodiments, in step (S1), when the waste plastic pyrolysis oil feedstock 1 is charged into the rotary kiln reactor 100 and then subjected to a heat treatment by increasing the temperature of the rotary kiln reactor 100, a solid component 5 comprising char, and pyrolysis gas, which is a gas component, are produced. Through the heat treatment, impurities such as chlorine, nitrogen, sulfur, and/or oxygen comprised in the waste plastic pyrolysis oil feedstock 1 may be removed.
In some embodiments, in the step (S1), the heat treatment may be performed by increasing the temperature of the rotary kiln reactor 100 to a third temperature.
In some embodiments, the third temperature may be 400 to 600° C. In some embodiments, the heat treatment is performed by increasing the temperature of the rotary kiln reactor 100 to the third temperature, such that impurities may be removed and lightening may be performed. In some embodiments, the third temperature may be 400 to 550° C., or 400 to 500° C. In some embodiments, as described below, before the step (S1), a heat treatment process comprising steps (S1-1) and (S1-2) is further performed, such that production of a high boiling point wax component 3 may be minimized, and/or the lightening efficiency may be further improved in conjunction with the steps (S2) to (S4).
In some embodiments, when the temperature of the rotary kiln reactor 100 is increased to the third temperature in the step (S1), a temperature increase rate may be 0.5° C./min to 5° C./min. In some embodiments, when the heat treatment is performed by increasing the temperature of the rotary kiln reactor 100 at the above temperature increase rate, the impurity removal efficiency and/or lightening efficiency may be improved. In some embodiments, the temperature increase rate may be 0.5° C./min to 3° C./min, or 0.5° C./min to 2° C./min.
In some embodiments, the step (S2) is a step of recovering a gas component from the product of step (S1), for example, the solid component 5 and the gas component are respectively separated at an outlet of the rotary kiln reactor 100, and the gas component may be recovered. As illustrated in
The gas component recovered in the step (S2) comprises a mixture of hydrocarbon oils comprising various molecular weight distributions, and also comprises the high boiling point wax component 3. The high boiling point wax component 3 refers to a hydrocarbon mixture that is insoluble in water during a reaction process or a transfer process or has a relatively high boiling point, and may refer to, for example, a wax component comprising a high molecular weight of C20 or higher. However, this is merely an example, and the standard of the high boiling point wax component 3 may vary depending on the environment in which it is to be separated and removed, such as production conditions or use environment of pyrolysis oil. In a case where the refined oil 10 is recovered by performing a refining process while comprising the high boiling point wax component 3 as is, problems such as blockage of the reactor or difficulty in transfer may occur, and a content of heavy oil in the recovered refined oil 10 is high, which makes it difficult to realize high-value-added waste plastic pyrolysis oil. As illustrated in
In some embodiments, a series of processes comprising the steps (S1) to (S4) is performed, such that refined oil 10 having significantly reduced impurities and/or a significantly improved degree of lightening may be obtained without process troubles such as blockage of the reactor.
In some embodiments, in step (S1), before the temperature of the rotary kiln reactor 100 is increased to the third temperature, a preliminary heat treatment is performed, such that the impurity removal efficiency and lightening efficiency may be further improved.
In some embodiments, the method may further comprise, before the step (S1): (S1-1) subjecting the waste plastic pyrolysis oil feedstock 1 to a first heat treatment by increasing a temperature of the rotary kiln reactor 100 to a first temperature; and (S1-2) subjecting the waste plastic pyrolysis oil feedstock 1 to a second heat treatment by increasing a temperature of the rotary kiln reactor 100 to a second temperature, wherein the temperature of the rotary kiln reactor 100 may be increased by sequentially heating the rotary kiln reactor 100 from the first temperature to the third temperature.
In some embodiments, the first temperature in the step (S1-1) may be 50 to 150° C. In some embodiments, the first heat treatment may be performed at the first temperature in an oxygen-free atmosphere for 20 to 300 minutes. The waste plastic pyrolysis oil feedstock 1 may comprise solid impurities such as a solid component formed by agglomeration of pyrolysis oil or a solid component unmelted during the waste plastic pyrolysis process. Accordingly, the first heat treatment process in the step (S1-1) is performed, such that uniformity and homogeneity of waste plastic pyrolysis oil may be improved, resulting in improvement of the process efficiency. In some embodiments, the first temperature may be 70 to 130° C., or 90 to 110° C.
In some embodiments, the second temperature in the step (S1-2) may be 220 to 300° C. In some embodiments, the second heat treatment may be performed at the second temperature in an oxygen-free atmosphere for 120 to 360 minutes. The second heat treatment of holding the second temperature for a predetermined time is performed, such that an impurity removal reaction such as a chlorine dissociation reaction from the waste plastic pyrolysis oil feedstock 1 may be sufficiently performed, and a resynthesis reaction of dissociated chlorine and pyrolyzed olefins may be suppressed. In some embodiments, the second temperature may be 230 to 290° C., or 240 to 280° C.
In some embodiments, before the step (S1), the preliminary heat treatment comprising the steps (S1-1) and (S1-2) is performed, such that impurities such as chlorine, nitrogen, sulfur, and/or oxygen may be effectively removed through a multi-stage temperature increase process of the rotary kiln reactor 100. In some embodiments, production of the high boiling point wax component 3 may be minimized, and accordingly, the process efficiency may be further improved in conjunction with the steps (S2) to (S4). The steps (S1-1) and (S1-2) may be performed after an initial step (S0), which will be described below.
In some embodiments, when the multi-stage temperature increase process comprising the steps (S1-1), (S1-2), and (S1) is performed, a pressure of the rotary kiln reactor 100 may be maintained at 0.02 MPa or less, or 0.01 MPa or less.
The multi-stage temperature increase process comprising the steps (S1-1), (S1-2), and (S1) may be performed in various aspects. In some embodiments, the temperature of the entire rotary kiln reactor 100 may be increased. As illustrated in
In some embodiments, the temperature of the rotary kiln reactor 100 may be increased by sequentially heating the rotary kiln reactor 100 from the first temperature to the third temperature in a direction from a feedstock inlet to an outlet. In some embodiments, the temperature of the rotary kiln reactor 100 is increased by sequentially heating the rotary kiln reactor 100 from the first temperature to the third temperature in the direction from the feedstock inlet to the outlet of the rotary kiln reactor 100, such that an optimal temperature gradient in the reactor is formed, and as a result, problems such as an increase in pressure and/or deterioration of pyrolysis efficiency may be solved.
In the case of the pyrolysis technique using the rotary kiln reactor 100 in the related art, a process of increasing a temperature of the reactor by heating the reactor from the outlet side has been performed to avoid an increase in pressure. However, in this case, the pyrolysis efficiency is reduced due to uneven heating.
In the case of the second aspect of the present disclosure, as illustrated in
In some embodiments, in the step (S1), the heat treatment may be performed by adding an additive. In some embodiments, the heat treatment is performed by adding an additive, such that the impurity removal efficiency and/or lightening efficiency may be further improved. As the additive, a known additive that may be used in the pyrolysis process of the waste plastic pyrolysis oil feedstock 1 may be used.
In some embodiments, the additive may comprise a metal oxide catalyst or a composite catalyst in which an active metal is supported on a metal oxide carrier. The metal oxide catalyst may be magnesium oxide, calcium oxide, potassium oxide, sodium oxide, and/or the like. In terms of the impurity removal efficiency and lightening efficiency, the composite catalyst in which an active metal is supported on a metal oxide carrier may be preferable. In some embodiments, the active metal may comprise at least one metal selected from copper, molybdenum, tungsten, and/or nickel. In some embodiments, the metal oxide carrier may comprise the metal oxide catalyst described above. Considering the impurity removal efficiency and lightening efficiency, a composite catalyst in which copper is supported on a calcium oxide carrier may be most preferable. For example, a Cu/CaO additive having a size (D50) of 48.9 μm and a BET specific surface area of 6.4 m2/g may be used.
In some embodiments, the method may further comprise, before the step (S1), a step (S0) comprising charging waste plastics 6 into a pyrolysis reactor 400 and pyrolyzing the waste plastics 6 at a temperature of 300 to 600° C. in a non-oxidizing atmosphere to produce a waste plastic pyrolysis oil feedstock 1. As illustrated in
In some embodiments, the pyrolysis reactor 400 may comprise a rotary kiln reactor 100. The step (S0) may be performed using a pyrolysis reactor 400 known in the related art, for example, a rotary kiln reactor 100, an autoclave reactor, a continuous reactor, an auger reactor, or a fluidized bed reactor. In some embodiments, it may be advantageous to perform the step (S0) using the rotary kiln reactor 100 in terms of improving the process efficiency.
In some embodiments, the step (S4) is a step of recovering the refined oil 10 from the gas component from which the high boiling point wax component 3 is removed, and in the step (S4), the refined oil 10 may be recovered by condensing the gas component from which the high boiling point wax component 3 is removed through a cooling and liquefaction process. In some embodiments, the condensed component may comprise an oil layer in which pyrolysis gas is liquefied, and a water layer formed by liquefaction of a by-product comprising water vapor generated during the heat treatment process, and finally, the refined oil 10 may be obtained through oil-water separation. The oil layer (refined oil) may be recovered directly by separating the oil layer and the water layer through the oil-water separation, or the oil layer (refined oil) may be recovered by adsorbing the water layer and then recovering the water layer. In some embodiments, an electric field may be applied to effectively separate the oil layer and the water layer, and the oil layer and the water layer may be separated in a short time by electrostatic adhesion due to application of the electric field. In some embodiments, an additive may be added as necessary to increase the oil-water separation efficiency, and the additive may be a common demulsifier known in the art. In some embodiments, as illustrated in
In some embodiments, the refined oil 10 recovered in the step (S4) may have a content of chlorine reduced by 50% or more compared to the content of chlorine in the waste plastic pyrolysis oil feedstock 1 in the step (S1). The refined oil 10 comprising a content of chlorine reduced by 50% or more may be obtained through a series of processes comprising the steps (S1) to (S4). In some embodiments, the refined oil 10 comprising a content of chlorine reduced by 60% or more may be obtained, or the refined oil 10 comprising a content of chlorine reduced by 70% or more may be obtained, or the refined oil 10 comprising a content of chlorine reduced by 90% or less may be obtained.
In some embodiments, the refined oil 10 recovered in the step (S4) may have a content of each of nitrogen, sulfur, and oxygen reduced by 20% or more compared to the waste plastic pyrolysis oil feedstock 1 in the step (S1). The refined oil 10 comprising a reduced content of each of nitrogen, sulfur, and oxygen as well as a reduced content of chlorine may be obtained through a series of processes comprising the steps (S1) to (S4). In some embodiments, the refined oil 10 comprising a content of each of nitrogen, sulfur, and/or oxygen reduced by 30% or more may be obtained, or the refined oil 10 comprising a content of each of nitrogen, sulfur, and/or oxygen reduced by 40% or more may be obtained, or the refined oil 10 comprising a content of each of nitrogen, sulfur, and oxygen reduced by 70% or less may be obtained.
In some embodiments, a weight ratio of the refined oil 10 recovered in the step (S4) to light oil in the waste plastic pyrolysis oil feedstock 1 in the step (S1) may be 1.3 or more. Typically, the waste plastic pyrolysis oil feedstock 1 contains an excessive amount of heavy oil such as LGO or VGO/AR compared to light oil such as H-Naphtha or KERO. However, the refined oil 10 having an improved degree of lightening may be obtained through a series of processes comprising the steps (S1) to (S4). In some embodiments, a weight ratio of the refined oil 10 to the light oil in the waste plastic pyrolysis oil feedstock 1 may be 1.5 or more, or 1.7 or more, or 3 or less.
In some embodiments, the present disclosure provides a device for refining waste plastic pyrolysis oil, the device comprising: a rotary kiln reactor 100 into which a waste plastic pyrolysis oil feedstock 1 is introduced; a gas separator 200 into which a gas component is introduced from the rotary kiln reactor 100; a condenser 300 into which a light gas component 4 is introduced from the gas separator 200; and a re-supply line in which a high boiling point wax component 3 is separated in the gas separator 200 and the separated high boiling point wax component 3 is re-supplied or recycled to the rotary kiln reactor 100. The rotary kiln reactor 100 has an advantage of high heat treatment efficiency because it applies heat uniformly while rotating. As described above, since the liquid waste plastic pyrolysis oil is introduced into the rotary kiln reactor 100 as a feedstock rather than solid waste plastics, the impurity removal efficiency and lightening efficiency may be significantly improved.
In some embodiments, the rotary kiln reactor 100 may sequentially comprise a first zone, a second zone, and a third zone in a direction from a feedstock inlet to an outlet. As described above, the rotary kiln reactor 100 comprising the first zone, the second zone, and the third zone may perform a multi-stage temperature increase process. In some embodiments, a step (S1-1), a step (S1-2), and a step (S1) may be performed in the first zone, the second zone, and the third zone, respectively. In this case, an optimal temperature gradient may be formed, and the impurity removal efficiency and/or lightening efficiency may be further improved. In some embodiments, a multi-stage temperature increase process may be performed by increasing a temperature of the entire rotary kiln reactor 100, and specific details are described in the section regarding the multi-stage temperature increase process comprising the steps (S1-1), (S1-2), and (S1).
In some embodiments, the rotary kiln reactor 100 may comprise a batch reactor. The batch reactor may prevent a disadvantage of a continuous reactor in which the entire process is stopped when a problem with feedstock input occurs during pyrolysis, and may achieve excellent overall process stability. As a non-limiting example, a continuous type rotary kiln reactor 100 may be used.
In some embodiments, the rotary kiln reactor 100 is connected to the gas separator 200, and at an outlet of the rotary kiln reactor 100, char or carbide, which is a solid component 5, and a pyrolysis gas component are separated from pyrolysis products, and only the pyrolysis gas component may be introduced into the top of the gas separator 200.
As the gas separator 200, a gas separator 200 known in the related art may be used, and the gas separator 200 may be designed, for example, in a distillation manner. A low boiling point pyrolysis gas and the high boiling point wax component 3 may be separated from the pyrolysis gas component by controlling a flow direction, a temperature gradient, and the like in a direction of a wall of the gas separator 200. However, this is merely an example, and the gas separator 200 may be designed in a manner known in the related art. In some embodiments, the high boiling point wax component 3 may be discharged through the bottom of the gas separator 200, and an external cooling unit may be provided at the bottom of the gas separator 200 for efficient discharge. In some embodiments, the separated high boiling point wax component 3 may be re-supplied to the rotary kiln reactor 100 through a re-supply line connected from the bottom of the gas separator 200 to the inlet of the rotary kiln reactor 100.
In some embodiments, the pyrolysis gas component from which the high boiling point wax component 3 is removed in the gas separator 200 may be cooled and liquefied in the condenser 300, and refined oil 10 may be recovered in a recovery tank. In some embodiments, the condenser 300 may comprise a zone through which a coolant flows, and the pyrolysis gas introduced into the condenser 300 may be liquefied by the coolant and converted into pyrolysis oil. When the pyrolysis oil produced in the condenser 300 rises to a predetermined level, the pyrolysis oil may be transferred to and recovered in the recovery tank. In some embodiments, the liquid pyrolysis oil recovered in the recovery tank may comprise an oil layer and a water layer, and oil-water separation may proceed in an oil-water separator to form an oil layer and a water layer in the liquid pyrolysis oil. When the oil layer and the water layer are separated, the oil layer may be immediately recovered or may be recovered after adsorbing the water layer, such that an oil layer (refined oil) in which a content of chlorine is minimized may be recovered. In some embodiments, an electric field application device may be provided to effectively separate the oil layer and the water layer. In a case where the water layer is discharged and adsorbed, a density is detected using a density profiler, such that it is possible to prevent the oil layer from being adsorbed together with the water layer when the water layer is adsorbed, and only the water layer may be effectively adsorbed.
As for the contents not further described in the device for refining waste plastic pyrolysis oil, the description of the method for refining waste plastic pyrolysis oil described above may be used as reference.
Hereinafter, the present disclosure will be described in detail with reference to Examples. However, these Examples are intended to describe the present disclosure in more detail, and the scope of the present disclosure is not limited by the following Examples.
A refining process of waste plastic pyrolysis oil was performed using a refining device comprising a rotary kiln reactor, a gas separator, and a condenser. As a feedstock charged into the rotary kiln reactor, liquid pyrolysis oil produced by pyrolyzing domestic waste plastics was used.
First, domestic mixed waste plastics comprising 3 wt % or more of PVC together with PE and PP were extruded at 250° C. to prepare 500 g of domestic waste plastic pellets. The domestic waste plastic pellets were put into a pyrolysis reactor, and then pyrolysis was performed at 400° C. in a non-oxidizing atmosphere for 250 minutes, thereby obtaining a waste plastic pyrolysis oil feedstock.
A content of impurities such as chlorine, nitrogen, sulfur, and oxygen comprised in the waste plastic pyrolysis oil feedstock was measured by ICP and XRF analysis, and it was measured that the content of chlorine was 564 ppm, the content of nitrogen was 1,083 ppm, the content of sulfur was 105 ppm, and the content of oxygen was 0.9 wt %.
The obtained waste plastic pyrolysis oil feedstock was put into the rotary kiln reactor, and then a heat treatment process was performed, thereby obtaining refined oil. Specifically, the rotary kiln reactor was operated under conditions of an inclination angle of 1.48 degrees, a rotation speed of 0.9 Nrpm, and an oxygen concentration of 0.5% or less, and the heat treatment process was performed by increasing the temperature of the rotary kiln reactor to 500° C. at a temperature increase rate of 0.75° C./min for 200 minutes.
Only a pyrolysis gas component was recovered from the heat treatment process product, and the recovered pyrolysis gas component was supplied to a gas separator. In the gas separator, a high boiling point wax component contained in the pyrolysis gas component was separated through the bottom of the gas separator, the separated high boiling point wax component was re-supplied once to the rotary kiln reactor through a re-supply line connected from the bottom of the gas separator to an inlet of the rotary kiln reactor, and the heat treatment process was repeated.
Finally, pyrolysis gas from which the high boiling point wax component was removed was recovered at the top of the gas separator, the recovered pyrolysis gas was passed through a condenser, and refined oil (waste plastic pyrolysis oil) was recovered in a recovery tank.
A reaction was performed under the same conditions as those in Example 1, except that a heat treatment process was performed by additionally putting an additive into the rotary kiln reactor. Specifically, as the additive, a Cu/CaO additive having a size (D50) of 48.9 μm and a BET specific surface area of 6.4 m2/g was used.
A reaction was performed under the same conditions as those in Example 1, except that a heat treatment process was performed by increasing the temperature of the rotary kiln reactor to 500° C. at a temperature increase rate of 6° C./min for 200 minutes.
A reaction was performed under the same conditions as those in Example 1, except that a heat treatment process was performed by applying a multi-stage temperature increase process to the rotary kiln reactor. Specifically, a first heat treatment process was performed by increasing the temperature of the rotary kiln reactor to 100° C. at a temperature increase rate of 1° C./min and then maintaining the temperature for 50 minutes. Thereafter, a second heat treatment process was performed by increasing the temperature of the rotary kiln reactor to 250° C. at a temperature increase rate of 0.9° C./min and then maintaining the temperature for 150 minutes. Thereafter, a heat treatment process was performed by increasing the temperature of the rotary kiln reactor to 500° C. at a temperature increase rate of 0.75° C./min for 200 minutes.
A reaction was performed under the same conditions as those in Example 1, except that refined oil was recovered in a recovery tank directly through a condenser without going through the process of separating the high boiling point wax component of the pyrolysis gas produced in the rotary kiln reactor and re-supplying the separated high boiling point wax component.
A reaction was performed under the same conditions as those in Example 1, except that domestic waste plastic pellets, rather than waste plastic pyrolysis oil, were applied as a feedstock to be put into the rotary kiln reactor. Specifically, 500 g of the domestic waste plastic pellets of Example 1 were put into the rotary kiln reactor, and then a heat treatment process was performed. The rotary kiln reactor was operated under conditions of an inclination angle of 1.48 degrees, a rotation speed of 0.9 Nrpm, and an oxygen concentration of 0.5% or less, and the heat treatment process was performed by increasing the temperature of the rotary kiln reactor to 500° C. at a temperature increase rate of 0.75° C./min for 200 minutes. Only a pyrolysis gas component was recovered from the heat treatment process product, and the recovered pyrolysis gas component was supplied to a gas separator. In the gas separator, a high boiling point wax component contained in the pyrolysis gas component was separated through the bottom of the gas separator, the separated high boiling point wax component was re-supplied once to the rotary kiln reactor through a re-supply line connected from the bottom of the gas separator to an inlet of the rotary kiln reactor, and the heat treatment process was repeated. Finally, pyrolysis gas from which the high boiling point wax component was removed was recovered at the top of the gas separator, the recovered pyrolysis gas was passed through a condenser, and waste plastic pyrolysis oil was recovered in a recovery tank.
Impurity Removal Effect
The contents of chlorine, nitrogen, sulfur, and oxygen contained in each of the feedstock and the obtained refined oil were measured by ICP and XRF analysis, and the impurity removal effect was evaluated.
Lightening Effect
Naphtha and KERO components contained in each of the feedstock and the refined oil were quantified through a gas chromatography method (ASTM D86), the combined weight was measured, and then a degree of lightening (increase in light oil content) was evaluated.
The analysis results are shown in Table 1.
Result Analysis
As shown in Table 1, in all Examples 1 to 4 according to the present disclosure, it could be confirmed that impurities such as chlorine, nitrogen, sulfur, and oxygen in the waste plastic pyrolysis oil feedstock were effectively reduced and refined oil in which a content of light oil (Naphtha and KERO) was increased was obtained.
Specifically, in Example 2 in which the heat treatment process was performed by adding the Cu/CaO additive to the rotary kiln reactor, it could be confirmed that the reduction effect of impurities such as chlorine, nitrogen, sulfur, and oxygen and the lightening effect were the best.
In Example 3 in which the heat treatment process was performed by setting the temperature increase rate of the rotary kiln reactor to 6° C./min, it could be confirmed that the reduction effect of the impurities such as chlorine, nitrogen, sulfur, and oxygen and the lightening effect were somewhat lower than those in Example 1, but were excellent compared to those in Comparative Examples 1 and 2.
In Example 4 in which the heat treatment process was performed by applying a multi-stage temperature increase process to the rotary kiln reactor, it could be confirmed that the reduction effect of impurities such as chlorine, nitrogen, sulfur, and oxygen and the lightening effect were more excellent than those in Example 1.
In Comparative Example 1 in which the process of separating the high boiling point wax component of the pyrolysis gas produced in the rotary kiln reactor and re-supplying the separated high boiling point wax component was not performed, it could be confirmed that the reduction effect of impurities such as chlorine, nitrogen, sulfur, and oxygen and the lightening effect were significantly reduced.
In Comparative Example 2 in which the domestic waste plastic pellets rather than waste plastic pyrolysis oil were applied as a reaction feedstock, it could be confirmed that the reduction effect of impurities such as chlorine, nitrogen, sulfur, and oxygen and the lightening effect were significantly reduced.
As set forth above, the method and device for refining waste plastic pyrolysis oil according to the present disclosure may effectively reduce impurities in waste plastic pyrolysis oil.
Further, the method and device for refining waste plastic pyrolysis oil according to the present disclosure may improve the lightening efficiency of waste plastic pyrolysis oil.
Further, the method and device for refining waste plastic pyrolysis oil according to the present disclosure may realize a stable process without corrosion or blockage of a reactor.
Although exemplary embodiments of the present disclosure have been described, the present disclosure is not limited to the exemplary embodiments, but may be prepared in various different forms, and it will be apparent to those skilled in the art to which the present disclosure pertains that the exemplary embodiments may be implemented in other specific forms without departing from the spirit or essential feature of the present disclosure. Therefore, it is to be understood that the exemplary embodiments described hereinabove are illustrative rather than restrictive in all aspects.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2022-0151305 | Nov 2022 | KR | national |
