JP2024071365A - Method and apparatus for refining waste plastic pyrolysis oil - Google Patents

Abstract

[Problem] To provide a method and apparatus for refining waste plastic pyrolysis oil. [Solution] To provide a method for refining waste plastic pyrolysis oil, comprising the steps of: charging a waste plastic pyrolysis oil feedstock 1 into a rotary kiln reactor 100, heating the reactor to heat-treat the waste plastic pyrolysis oil feedstock, recovering a gas component 2 from the product of the step, separating a high-boiling wax component 3 from the recovered gas component and resupplying the separated high-boiling wax component to the reactor, and recovering refined oil 10 from the gas component from which the high-boiling wax component has been removed. Also provided is a refining apparatus including a rotary kiln reactor, a gas separator 200 for receiving gas components from the reactor, and a condenser 300 for receiving light gas components from the gas separator, and including a resupply line configured to resupply the high-boiling wax component separated in the gas separator to the reactor. [Selected Figure] FIG.

Description

This disclosure relates to a method and apparatus for refining waste plastic pyrolysis oil.

Waste plastic is manufactured using petroleum as a raw material, has a low recyclability, and is often disposed of as garbage. This type of waste takes a long time to decompose in natural conditions, polluting the soil and causing serious environmental pollution. One method for recycling waste plastic is to pyrolyze it and convert it into usable oil, and this oil is called waste plastic pyrolysis oil.

However, the pyrolysis oil obtained by pyrolyzing waste plastics has a higher content of impurities such as chlorine, nitrogen, and metals compared to oil produced from crude oil using conventional methods, so it cannot be immediately used as a high-value-added fuel such as gasoline or diesel oil and must go through a post-processing process.

In a conventional post-treatment process, waste plastic pyrolysis oil is hydrotreated in the presence of a hydrogenation catalyst to remove chlorine, nitrogen, or other metal impurities, but in this process, the high content of chlorine contained in the waste plastic pyrolysis oil produces excess HCl, which causes problems such as corrosion of the equipment, abnormal reactions, and deterioration of product properties. In particular, the HCl reacts with nitrogen compounds to produce ammonium salts (NH ₄ Cl), which not only corrode the reactor and reduce its durability, but also cause various process problems such as generation of differential pressure, clogging of the reactor, and reduced process efficiency.

On the other hand, waste plastic pyrolysis oil is a hydrocarbon oil mixture with various boiling points and various molecular weight distributions. Since the composition and reaction activity of impurities in the pyrolysis oil vary depending on the boiling point and molecular weight distribution characteristics of the hydrocarbon mixture, it cannot be used immediately in the petrochemical industry or on-site, and requires a high value-added process such as a separation process based on boiling point or a lightening process. Among the hydrocarbon oil mixtures, olefins, especially light olefins such as ethylene and propylene, are widely used in the petrochemical industry.

Hydrocracking is carried out as a lightening process to add value to waste plastic pyrolysis oil, but compared to crude oil, natural gas, or naphtha fractions, waste plastic pyrolysis oil contains excessive amounts of impurities such as chlorine, nitrogen, sulfur, oxygen, and metals, and there is a problem that the reaction activity is significantly reduced by these impurities during the hydrocracking process. There is also a problem that the hydrocracking process must be carried out separately from the hydrotreatment process, which reduces the process efficiency.

Therefore, there is a need for technology that can effectively remove impurities from pyrolysis oil and lighten the pyrolysis oil without using post-processing steps such as hydrotreating or hydrocracking.

The objective of this disclosure is to provide a method and apparatus for refining waste plastic pyrolysis oil that can effectively reduce impurities in the waste plastic pyrolysis oil and increase the added value of the pyrolysis oil.

Another object of the present disclosure is to provide a method and apparatus for refining waste plastic pyrolysis oil that can be stably carried out without corroding or clogging the reactor.

The present disclosure provides a method for refining waste plastic pyrolysis oil, including the steps of: charging a waste plastic pyrolysis oil feedstock into a rotary kiln-type reactor, heating the rotary kiln-type reactor to heat-treat the waste plastic pyrolysis oil feedstock (S1); recovering gas components from the product of the step (S1) (S2); separating high-boiling wax components from the recovered gas components and resupplying the separated high-boiling wax components to the rotary kiln-type reactor of the step (S1) (S3); and recovering refined oil from the gas components from which the high-boiling wax components have been removed (S4).

The waste plastic pyrolysis oil feedstock is preferably a liquid pyrolysis oil containing naphtha: 10-30% by weight, KERO: 20-30% by weight, LGO: 10-30% by weight, and VGO: 30-50% by weight.

In the step (S1), it is preferable to heat-treat the rotary kiln-type reactor by increasing the temperature to a third temperature.
The third temperature is preferably in the range of 400 to 600°C.
In the step (S1), the rate of temperature rise to the third temperature is preferably 0.5° C./min to 5° C./min.

Before step (S1), the method further includes a step (S1-1) of heating the rotary kiln reactor to a first temperature and subjecting the waste plastic pyrolysis oil feedstock to a first heat treatment, and a step (S1-2) of heating the rotary kiln reactor to a second temperature and subjecting the waste plastic pyrolysis oil feedstock to a second heat treatment, and it is preferable that the temperature of the rotary kiln reactor is increased by sequentially heating the rotary kiln reactor from the first temperature to the third temperature.

The first temperature is preferably from 50 to 150°C.
The second temperature is preferably from 220 to 300°C.
The heat treatment in the step (S1) is preferably carried out by adding an additive.
The additive preferably contains a metal oxide catalyst or a composite catalyst in which an active metal is supported on a metal oxide support.

It is preferable to further include a step (S0) prior to the step (S1) of feeding waste plastic into a pyrolysis reactor and pyrolyzing the waste plastic at a temperature of 300 to 600° C. in a non-oxidizing atmosphere to produce a waste plastic pyrolysis oil raw material.
The pyrolysis reactor preferably comprises a rotary kiln type reactor.

It is preferable that the refined oil recovered in step (S4) has a chlorine content reduced by 50% or more compared to the waste plastic pyrolysis oil feedstock in step (S1).

It is preferable that the refined oil recovered in step (S4) has a nitrogen, sulfur, and oxygen content reduced by 20% or more compared to the waste plastic pyrolysis oil feedstock in step (S1).

The ratio of the light fraction of the refined oil recovered in step (S4) to the light fraction of the waste plastic pyrolysis oil feedstock in step (S1) is preferably 1.3 or more by weight.

The present disclosure also provides a waste plastic pyrolysis oil refining apparatus including a rotary kiln-type reactor configured to receive waste plastic pyrolysis oil, a gas separator configured to receive gas components from the rotary kiln-type reactor, a condenser configured to receive light gas components from the gas separator, and a resupply line configured to resupply high-boiling-point wax components separated in the gas separator to the rotary kiln-type reactor.

The rotary kiln-type reactor preferably includes a first region, a second region, and a third region in this order from the raw material inlet to the discharge outlet.
The rotary kiln type reactor preferably comprises a batch reactor.

The waste plastic pyrolysis oil refining method and refining apparatus disclosed herein can effectively reduce impurities in the waste plastic pyrolysis oil.
The refining method and refining apparatus for waste plastic pyrolysis oil according to the present disclosure can improve the efficiency of lightening the waste plastic pyrolysis oil.

The method and apparatus for refining waste plastic pyrolysis oil disclosed herein can be carried out stably without corroding or clogging the reactor.

FIG. 1 is a block diagram of a method and apparatus for refining waste plastic pyrolysis oil according to one embodiment. A block diagram of a method and apparatus for refining waste plastic pyrolysis oil according to one embodiment, comprising a step of separating a solid component 5 including char from a rotary kiln reactor 100 and resupplying the solid component 5 together with a high-boiling point wax component 3 to the rotary kiln reactor 100. FIG. 1 is a block diagram of a method and apparatus for refining waste plastic pyrolysis oil according to one embodiment, the method including a step of pyrolyzing waste plastic 6 in a pyrolysis reactor 400 to produce a waste plastic pyrolysis oil raw material 1. FIG. 1 is a block diagram of a method and apparatus for refining pyrolysis oil, including a step of resupplying refined oil 10 recovered from a condenser 300 together with a high-boiling wax component 3 to a rotary kiln-type reactor 100 according to one embodiment. FIG. 5(a) is a diagram showing a rotary kiln type reactor according to one embodiment, and FIG. 5(b) is a diagram showing a rotary kiln type reactor including a first region, a second region, and a third region according to another embodiment.

Unless otherwise defined, technical and scientific terms used in this specification have the meanings that are commonly understood by those with ordinary knowledge in the technical field to which this invention belongs, and in the following description and accompanying drawings, explanations of known functions and configurations that may unnecessarily obscure the gist of this disclosure will be omitted.

As used herein, the terms numbers may be construed to include plurals unless otherwise indicated.
Numerical ranges used herein include lower and upper limits and all values within the range, increments logically derived from the form and width of the ranges defined, all values limited therein, and all possible combinations of upper and lower limits of numerical ranges limited in different forms from each other. Unless otherwise specified herein, values outside the numerical ranges that may occur due to experimental error or rounding of values are included in the defined numerical ranges.

As used herein, "comprising" is an open-ended term having the same meaning as "comprising," "containing," "having," "characterized," and similar expressions, and does not exclude additional, unrecited elements, materials, or steps.

The unit of % referred to in this specification means % by weight, unless otherwise specified.
The ppm units referred to in this specification mean ppm by mass unless otherwise defined.

Boiling points referred to herein mean boiling points at 1 atmosphere pressure, unless otherwise defined.
Density referred to in this specification means density at 1 atmosphere and 25°C, unless otherwise defined.

The high boiling wax component referred to in this specification means, unless otherwise defined, a hydrocarbon mixture that can exist in a solid state without dissolving in water during the reaction or transportation process.
The impurities referred to in this specification are meant to include chlorine impurities, nitrogen impurities, oxygen impurities, or sulfur impurities, unless otherwise defined.

The pyrolysis oil obtained by pyrolyzing waste plastics has a higher content of impurities such as chlorine, nitrogen, and metals than oil produced from crude oil using conventional methods, so it cannot be used immediately as a high-value-added fuel such as gasoline or diesel oil and must go through a post-processing process.

In the conventional post-treatment process, the waste plastic pyrolysis oil is hydrotreated under a hydrogenation catalyst to remove chlorine, nitrogen, and other metal impurities. However, the high content of chlorine impurities contained in the waste plastic pyrolysis oil produces excess HCl, which causes problems such as corrosion of the equipment, abnormal reaction, and deterioration of product properties. In particular, the HCl reacts with nitrogen compounds to produce ammonium salts (NH ₄ Cl), which not only corrodes the reactor and reduces its durability, but also causes various process problems such as differential pressure and reduced process efficiency. In addition, a hydrocracking process is performed as a lightening process for adding high value to the waste plastic pyrolysis oil. However, as described above, the waste plastic pyrolysis oil contains excess impurities such as chlorine, nitrogen, and metals compared to crude oil, natural gas, naphtha fraction, etc., and there is a problem that the reaction activity is significantly reduced due to the impurities during the hydrocracking process. In addition, since the hydrocracking process is performed separately from the hydrotreatment process, there is a problem that the process efficiency is also reduced.

Therefore, the present disclosure provides a method for refining waste plastic pyrolysis oil, including the steps of (S1) charging a waste plastic pyrolysis oil raw material into a rotary kiln reactor and heating the rotary kiln reactor to heat the waste plastic pyrolysis oil raw material, (S2) recovering gas components from the product of the (S1) step, (S3) separating high-boiling wax components from the recovered gas components and resupplying the separated high-boiling wax components to the rotary kiln reactor of the (S1) step, and (S4) recovering refined oil from the gas components from which the high-boiling wax components have been removed. This makes it possible to effectively remove impurities in the waste plastic pyrolysis oil and improve the degree of lightening to realize high added value of the pyrolysis oil, and the process can be stably carried out without corroding or clogging the reactor.

In detail, the (S1) step is a step of loading the waste plastic pyrolysis oil raw material 1 into a rotary kiln type reactor 100, heating the rotary kiln type reactor, and heat-treating the waste plastic pyrolysis oil raw material. At this time, the waste plastic pyrolysis oil raw material 1 may be a liquid hydrocarbon oil mixture produced by high-temperature pyrolysis of waste plastic in the (S0) step described later.

Considering the unique characteristics of the rotary kiln reactor 100, which heats the reactor from below and rotates it to carry out the reaction, and liquid pyrolysis oil, the efficiency of removing impurities and the efficiency of lightening the waste plastics are significantly improved by using liquid waste plastic pyrolysis oil as the raw material rather than solid waste plastics.

In other words, this disclosure does not use solid waste plastic as a raw material to produce pyrolysis oil from it, but rather relates to a refining method that uses waste plastic pyrolysis oil as a raw material to produce refined oil 10 from it, and specifically relates to a refining method for waste plastic pyrolysis oil that significantly improves the efficiency of removing impurities and converting the oil into lighter oil.

The waste plastic pyrolysis oil raw material 1 may contain various impurities in addition to the hydrocarbon oil. For example, it may contain impurities such as chlorine compounds, nitrogen compounds, sulfur compounds, oxygen compounds, and metal compounds. Specifically, it may contain 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 1 vol % or more of conjugated diolefins.

The hydrocarbon oil mixture present in the waste plastic pyrolysis oil feedstock 1 may contain naphtha having a carbon number of 8 or less and a boiling point of 150°C or less, KERO having a carbon number of 9 to 17 and a boiling point of 150 to 265°C, LGO having a carbon number of 18 to 20 and a boiling point of 265 to 340°C, and VGO having a carbon number of 21 or more and a boiling point of 340°C or more in various ranges. Usually, heavy fractions such as LGO or VGO/AR are contained in excess of light fractions such as naphtha or KERO. However, this is merely an example, and the composition of the waste plastic pyrolysis oil feedstock 1 is not necessarily limited to this, and may be present in a variety of forms within the range of 100% by weight of the above composition.

In one embodiment, the waste plastic pyrolysis oil feedstock 1 is preferably a liquid pyrolysis oil containing 10-30% by weight naphtha, 20-30% by weight KERO, 10-30% by weight LGO, and 30-50% by weight VGO. In addition, the waste plastic pyrolysis oil feedstock 1 is more preferably a liquid pyrolysis oil containing 10-30% by weight naphtha with a carbon number of 8 or less and a boiling point of 150°C or less, 20-30% by weight KERO with a carbon number of 9-17 and a boiling point of 150-265°C, 10-30% by weight LGO with a carbon number of 18-20 and a boiling point of 265-340°C, and 30-50% by weight VGO with a carbon number of 21 or more and a boiling point of 340°C or more. When using liquid pyrolysis oil that satisfies the above composition ratio, the efficiency of impurity removal and lightening efficiency are improved, which is advantageous.

Hereinafter, the refining method and refining apparatus for waste plastic pyrolysis oil according to the present disclosure will be described with reference to FIGS. 1 to 4.
In step (S1), the waste plastic pyrolysis oil raw material 1 is charged into a rotary kiln reactor 100, and the rotary kiln reactor is heated to heat-treat the waste plastic pyrolysis oil raw material 1, thereby generating a solid component 5 containing char and a pyrolysis gas which is a gas component. The heat treatment can remove impurities such as chlorine, nitrogen, sulfur, or oxygen contained in the waste plastic pyrolysis oil raw material 1.

In one embodiment, the step (S1) may include heat treatment by increasing the temperature of the rotary kiln-type reactor 100 to a third temperature.
In one embodiment, the third temperature is 400 to 600° C. By heating the rotary kiln reactor 100 to the third temperature and performing heat treatment, impurities can be removed and lightening can be performed. Preferably, the third temperature is 400 to 550° C., more preferably 400 to 500° C. In addition, as described below, by further performing heat treatment processes of steps (S1-1) and (S1-2) before the step (S1), the generation of high boiling point wax component 3 can be minimized, and the lightening efficiency can be further improved when combined with steps (S2) to (S4).

In one embodiment, in step (S1), the heating rate when heating to the third temperature is 0.5°C/min to 5°C/min. When the temperature is raised at this heating rate and heat treatment is performed, the efficiency of removing impurities and the efficiency of reducing the weight can be improved. Preferably, the heating rate is 0.5°C/min to 3°C/min, and more preferably, 0.5°C/min to 2°C/min.

The (S2) step is a step of recovering gas components from the product of the (S1) step. Specifically, the solid component 5 and the gas component 2 are separated at the outlet of the rotary kiln-type reactor 100, and the gas component 2 can be recovered. As shown in FIG. 2, the separated solid component 5 may be re-supplied to the reactor 100 of the (S1) step together with the high-boiling point wax component 3 separated in the (S3) step for reprocessing. This can reduce waste disposal costs, improve economy, and improve process efficiency.

The gas component 2 recovered in the (S2) step includes a hydrocarbon oil mixture having various molecular weight distributions, including a high-boiling wax component 3. The high-boiling wax component 3 means a hydrocarbon mixture that is not soluble in water during the reaction or transportation process or has a relatively high boiling point, and may mean, for example, a wax component having a high molecular weight of 20 or more carbon atoms. However, this is only an example, and the standard for the high-boiling wax component 3 may vary depending on the environment in which the pyrolysis oil is to be separated and removed, such as the production conditions or use environment of the pyrolysis oil. When the refinery process is performed while the high-boiling wax component 3 is still contained, problems such as clogging of the reactor 100 or difficulties in transportation may occur, and the content of heavy fractions in the recovered refinery oil 10 is high, making it difficult to realize high added value of the waste plastic pyrolysis oil. As shown in FIG. 1, the high boiling wax component 3 is separated from the recovered gas component 2, and the separated high boiling wax component 3 is re-supplied to the rotary kiln reactor 100 in the step (S1) (S3), and the refined oil 10 is recovered from the gas component 4 from which the high boiling wax component 3 has been removed (S4). This makes it possible to obtain refined oil 10 with improved impurity removal and lightening, and to solve problems with process troubles such as reactor blockage. In this case, the step of separating the high boiling wax component 3 in the step (S3) and re-supplying the separated high boiling wax component 3 to the rotary kiln reactor 100 may be repeated one or more times.

In other words, a series of processes including steps (S1) to (S4) can produce refined oil 10 with significantly reduced impurities and significantly improved lightness without process troubles such as reactor clogging.

In the step (S1), by performing a preliminary heat treatment process before heating the rotary kiln reactor 100 to the third temperature, the efficiency of impurity removal and the efficiency of lightening can be further improved.

In one embodiment, before the step (S1), the method further includes a step (S1-1) of heating the rotary kiln reactor 100 to a first temperature and subjecting the waste plastic pyrolysis oil feedstock to a first heat treatment, and a step (S1-2) of heating the rotary kiln reactor to a second temperature and subjecting the waste plastic pyrolysis oil feedstock to a second heat treatment, and it is preferable that 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 one embodiment, the first temperature in step (S1-1) may be 50 to 150°C. In particular, the first heat treatment may be performed at the first temperature for 20 to 300 minutes in an oxygen-free atmosphere. The waste plastic pyrolysis oil raw material 1 may contain solid impurities such as solid components formed by agglomeration of the pyrolysis oil or solid components that are not melted during the waste plastic pyrolysis process. Therefore, by performing the first heat treatment process in step (S1-1), the uniformity and homogeneity of the waste plastic pyrolysis oil can be improved, and the process efficiency can be improved. The first temperature is preferably 70 to 130°C, more preferably 90 to 110°C.

The second temperature in step (S1-2) is 220 to 300°C, and preferably, the second heat treatment may be performed at the second temperature and in an oxygen-free atmosphere for 120 to 360 minutes. By performing the second heat treatment, which is held at the second temperature for a specific time, impurity removal reactions such as chlorine dissociation reactions can be sufficiently carried out from the waste plastic pyrolysis oil feedstock 1, and the resynthesis reaction of dissociated chlorine and pyrolyzed olefins can be suppressed. The second temperature is preferably 230 to 290°C, more preferably 240 to 280°C.

In this way, by performing the preliminary heat treatments of steps (S1-1) and (S1-2) before step (S1), impurities such as chlorine, nitrogen, sulfur, or oxygen can be effectively removed by the multi-stage heating process of the rotary kiln reactor 100. In addition, the generation of high-boiling point wax components 3 can be minimized, and the process efficiency can be further improved when combined with steps (S2) to (S4). Steps (S1-1) and (S1-2) may be performed after step (S0) described below.

In one embodiment, when a multi-stage heating process including steps (S1-1), (S1-2), and (S1) is performed, the pressure in the rotary kiln reactor 100 can be maintained at 0.02 MPa or less, and preferably 0.01 MPa or less.

The multi-stage heating process including the steps (S1-1), (S1-2), and (S1) may be carried out in various ways. For example, as a first way, the temperature may be raised throughout the rotary kiln reactor 100. As shown in FIG. 5(a), the temperature of the entire rotary kiln reactor 100 may be raised. Preferably, the steps of heating the entire rotary kiln reactor 100 to a first temperature and performing a first heat treatment (S1-1), heating to a second temperature and performing a second heat treatment (S1-2), and heating to a third temperature and performing a heat treatment (S1) may be carried out in sequence.

As another embodiment, the second aspect, it is preferable to sequentially heat the rotary kiln reactor 100 from the raw material inlet to the discharge outlet to the first to third temperatures. By sequentially heating and raising the temperature of the rotary kiln reactor 100 from the raw material inlet to the discharge outlet to the first to third temperatures, an optimal temperature gradient can be formed in the reactor, and the problems of pressure rise and reduced pyrolysis efficiency can be solved. Conventionally, in the case of pyrolysis technology using a rotary kiln reactor 100, a process of heating the reactor from the discharge outlet side to avoid pressure rise is performed, but in this case, there is a problem that the pyrolysis efficiency is reduced due to uneven heating. In the second aspect of the present disclosure, as shown in FIG. 5(b), a first region where burner 1 is located, a second region where burner 2 is located, and a third region where burner 3 is located may be formed in the direction from the raw material inlet to the outlet of the rotary kiln-type reactor 100, and the steps of heating to a first temperature in the first region and performing a first heat treatment (S1-1), heating to a second temperature in the second region and performing a second heat treatment (S1-2), and heating to a third temperature in the third region and performing a heat treatment (S1) may be performed sequentially. This is more advantageous because it is possible to form an optimal temperature gradient, and by minimizing the generation of high-boiling point wax component 3, it is possible to further improve the process efficiency when linked with the steps (S2) to (S4).

In one embodiment, the heat treatment in step (S1) may be performed with the addition of an additive. By adding an additive, the efficiency of removing impurities and the efficiency of converting the material into lighter materials can be further improved. As the additive, a known additive that can be used in the thermal decomposition process of the waste plastic pyrolysis oil feedstock 1 may be used.

In one embodiment, the additive may include 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, or the like. In terms of impurity removal efficiency and lightening efficiency, a composite catalyst in which an active metal is supported on a metal oxide carrier is preferred. The active metal may include at least one metal selected from copper, molybdenum, tungsten, and nickel. The metal oxide carrier may include the metal oxide catalyst described above. In consideration of impurity removal efficiency and lightening efficiency, a composite catalyst in which copper is supported on a calcium oxide carrier is most preferred.

In one embodiment, the method may further include a step (S0) prior to the step (S1) of charging waste plastic 6 into a pyrolysis reactor 400 and pyrolyzing it at a temperature of 300 to 600 ° C. and in a non-oxidizing atmosphere to produce waste plastic pyrolysis oil feedstock 1. As shown in FIG. 3, the solid waste plastic 6 may be charged into a pyrolysis reactor 400 and pyrolyzed to produce waste plastic pyrolysis oil feedstock 1, and the produced waste plastic pyrolysis oil feedstock 1 may be charged into a rotary kiln type reactor 100 to perform the heat treatment process of the step (S1). The waste plastic may be household plastic waste (domestic waste plastic) or industrial plastic waste (industrial waste plastic). The household waste plastic is a plastic in which PVC, PS, PET, PBT, etc. other than PE and PP are mixed, and is preferably a mixed waste plastic containing 3% by weight or more of PVC along with PE and PP. The industrial waste plastics are industrial wastes such as scraps and defective products generated during manufacturing processes in the industry, and the majority of them are PE/PP. The non-oxidizing atmosphere is an atmosphere in which the waste plastics do not oxidize (burn), and stable and efficient pyrolysis can be performed in the non-oxidizing atmosphere at a temperature of 300 to 600°C for 150 to 350 minutes, and if the above maintenance time is met, activation of the creation of a non-oxidizing atmosphere and sufficient pyrolysis can be performed.

In one embodiment, the pyrolysis reactor 400 may include a rotary kiln-type reactor 100. The (S0) step may be performed using a conventionally known pyrolysis reactor 400, such as a rotary kiln-type reactor 100, an autoclave reactor, a continuous reactor, an auger reactor, or a fluidized bed reactor, and it is particularly advantageous to use a rotary kiln-type reactor 100 in terms of improving process efficiency.

The (S4) step is a step of recovering refined oil 10 from the gas component from which the high-boiling wax component 3 has been removed, and refined oil 10 can be recovered by condensing gas component 4 from which the high-boiling wax component 3 has been removed through a cooling and liquefaction process. Specifically, the condensed components may include an oil layer formed by liquefying the pyrolysis gas, as well as a water layer formed by liquefying a by-product containing water vapor generated during the heat treatment process, and refined oil 10 can be finally obtained by oil-water separation. The oil layer and the water layer are separated by the oil-water separation, and the oil layer (refined oil) can be recovered by either immediately recovering the oil layer (refined oil) or recovering it after adsorption of the water layer. An electric field may be applied to effectively separate the oil layer and the water layer, and the oil layer and the water layer can be separated in a short time by electrostatic adhesion due to the application of an electric field. In addition, an additive may be added as necessary to increase the efficiency of the oil-water separation, and the additive may be a conventional demulsifier well known in the art. In one embodiment, as shown in FIG. 4, the refined oil 10 recovered in the step (S4) may be re-supplied to the rotary kiln reactor 100 in the step (S1) for reprocessing. This can further improve the impurity removal efficiency and the lightening effect. The re-supply process may be repeated one or more times.

In one embodiment, the refined oil 10 recovered in step (S4) may have a chlorine content reduced by 50% or more compared to the waste plastic pyrolysis oil feedstock 1 in step (S1). A series of processes including steps (S1) to (S4) can produce refined oil 10 with a chlorine content reduced by 50% or more. Preferably, refined oil 10 with a chlorine content reduced by 60% or more can be produced, more preferably refined oil 10 with a chlorine content reduced by 70% or more, and even more preferably refined oil 10 with a chlorine content reduced by 90% or less can be produced.

In one embodiment, the refined oil 10 recovered in the (S4) step may have nitrogen, sulfur, and oxygen contents reduced by 20% or more compared to the waste plastic pyrolysis oil feedstock 1 in the (S1) step. Through a series of processes including the (S1) to (S4) steps, refined oil 10 can be obtained in which the contents of not only chlorine but also nitrogen, sulfur, and oxygen are reduced. Preferably, refined oil 10 in which the contents of nitrogen, sulfur, and oxygen are reduced by 30% or more can be obtained, more preferably, refined oil 10 in which the contents of nitrogen, sulfur, and oxygen are reduced by 40% or more can be obtained, and even more preferably, refined oil 10 in which the contents of nitrogen, sulfur, and oxygen are reduced by 70% or less can be obtained.

In one embodiment, the ratio of the light fraction of the refined oil 10 recovered in the step (S4) to the light fraction of the waste plastic pyrolysis oil feedstock 1 in the step (S1) may be 1.3 or more by weight. Usually, the waste plastic pyrolysis oil feedstock 1 contains an excess of heavy fractions such as LGO or VGO/AR compared to light fractions such as H-naphtha or KERO, but a series of processes including the steps (S1) to (S4) can produce refined oil 10 with an improved degree of lightness. The ratio of the light fraction of the refined oil 10 to the light fraction of the waste plastic pyrolysis oil feedstock 1 by weight is preferably 1.5 or more, more preferably 1.7 or more, and even more preferably 3 or less.

The present disclosure also provides a waste plastic pyrolysis oil refining device, comprising a rotary kiln reactor 100 configured to receive a waste plastic pyrolysis oil raw material 1, a gas separator 200 configured to receive a gas component from the rotary kiln reactor 100, a condenser 300 configured to receive a light gas component 4 from the gas separator, and a resupply line configured to resupply the high boiling point wax component 3 separated in the gas separator to the rotary kiln reactor 100. The rotary kiln reactor 100 has the advantage of high heat treatment efficiency because it applies heat uniformly while rotating. As described above, by introducing waste plastic pyrolysis oil, which is a liquid component, as a raw material into the rotary kiln reactor 100 instead of waste plastic, which is a solid component, the efficiency of removing impurities and the efficiency of lightening are significantly improved.

In one embodiment, the rotary kiln type reactor 100 may include a first region, a second region, and a third region in sequence from the raw material inlet to the discharge port. As described above, the rotary kiln type reactor may include the first region, the second region, and the third region to perform a multi-stage heating process. Specifically, the (S1-1) step may be performed in the first region, the (S1-2) step may be performed in the second region, and the (S1) step may be performed in the third region. In this case, an optimal temperature gradient may be formed, and the efficiency of removing impurities and the efficiency of lightening may be further improved. In another embodiment, the entire rotary kiln type reactor 100 may be heated to perform a multi-stage heating process, and the specific content of the multi-stage heating process has been described above in the paragraph regarding the multi-stage heating process including the (S1-1), (S1-2), and (S1) steps.

In one embodiment, the rotary kiln reactor 100 may include a batch reactor. A batch reactor can prevent the drawback of a continuous reactor in that the entire process is interrupted if a problem occurs with the input of raw materials during pyrolysis, and can provide excellent overall process stability. As a non-limiting example, a continuous rotary kiln reactor 100 can also be used.

The rotary kiln type reactor 100 is connected to a gas separator 200, and the solid components 5 in the pyrolysis product, char or carbonized matter, and the pyrolysis gas components are separated at the outlet of the rotary kiln type reactor 100, and only the pyrolysis gas components can flow into the upper part of the gas separator 200.

The gas separator 200 may be a conventional gas separator 200, and may be designed, for example, by a distillation method. The low boiling point pyrolysis gas and the high boiling point wax component 3 may be separated from the pyrolysis gas component by adjusting the flow direction in the wall direction of the gas separator 200, the temperature gradient, etc., but this is only one example, and may be designed by a conventional method. The high boiling point wax component 3 is discharged to the lower part of the gas separator 200, and an external cooling means may be provided in the lower part of the gas separator 200 for efficient discharge. The separated high boiling point wax component 3 may be resupplied to the rotary kiln type reactor 100 through a resupply line connected from the lower part of the gas separator 200 to the inlet of the rotary kiln type reactor 100.

The pyrolysis gas components from which the high boiling point wax components 3 have been removed in the gas separator 200 can be cooled and liquefied in the condenser 300, and refined oil 10 can be recovered in a recovery tank. The condenser 300 includes an area in which cooling water flows, and the pyrolysis gas flowing into the condenser 300 can be liquefied by the cooling water and converted into pyrolysis oil. When the pyrolysis oil generated in the condenser 300 rises to a predetermined water level, it can be transferred and stored in a recovery tank. The liquid pyrolysis oil recovered in the recovery tank can include an oil layer and a water layer, and oil-water separation can be performed 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 can be recovered immediately or after adsorption of the water layer, thereby recovering an oil layer (refined oil) with minimized chlorine. An electric field application device can be provided to effectively separate the oil layer and the water layer. When the water layer is discharged and adsorbed, a density profiler is used to detect the density, which can prevent the oil layer from being adsorbed when the water layer is adsorbed, allowing only the water layer to be effectively adsorbed.

For matters not explained below regarding the waste plastic pyrolysis oil refining apparatus, please refer to the contents described in the above-mentioned method for refining waste plastic pyrolysis oil.

The present disclosure will be described in more detail below with reference to examples. However, these are intended to provide a more detailed explanation and the scope of the rights is not limited to the following examples.

Example 1
The waste plastic pyrolysis oil was refined through a refining device including a rotary kiln reactor, a gas separator, and a condenser. The raw material fed into the rotary kiln reactor was liquid pyrolysis oil produced by pyrolyzing household waste plastic.

First, a household waste plastic mixture containing 3% by weight or more of PVC along with PE and PP was extruded at 250°C to produce 500g of household waste plastic pellets. The household waste plastic pellets were then placed in a pyrolysis reactor and pyrolyzed at 400°C for 250 minutes in a non-oxidizing atmosphere to obtain waste plastic pyrolysis oil raw material.

The impurities contained in the waste plastic pyrolysis oil feedstock, chlorine, nitrogen, sulfur, and oxygen contents, were measured by ICP and XRF analysis, and the chlorine content was measured to be 564 ppm, the nitrogen content to be 1083 ppm, the sulfur content to be 105 ppm, and the oxygen content to be 0.9 wt%.

The waste plastic pyrolysis oil raw material obtained above was fed into a rotary kiln reactor, and then a heat treatment process was carried out to obtain 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 temperature was raised to 500°C at a heating rate of 0.75°C/min, and the heat treatment process was carried out for 200 minutes.

Only the pyrolysis gas components were recovered from the heat treatment process product and supplied to a gas separator. In the gas separator, the high boiling point wax components contained in the pyrolysis gas components were separated into the lower part of the gas separator, and the separated high boiling point wax components were resupplied once to the rotary kiln type reactor through a resupply line connected from the lower part of the gas separator to the inlet of the rotary kiln type reactor, and the heat treatment process was repeated.

Finally, the pyrolysis gas from which the high-boiling wax components have been removed is recovered at the top of the gas separator, passed through a condenser, and refined oil (waste plastic pyrolysis oil) is recovered in a recovery tank.

Example 2
The reaction was carried out under the same conditions as in Example 1, except that an additive was added to the rotary kiln reactor and a heat treatment process was carried out. Specifically, the additive had a size (D50) of 48.9 μm, a BET specific surface area of 6.4 m ² /g, and was composed of a composite catalyst of Cu (active metal)/CaO (metal oxide support).

Example 3
The reaction was carried out under the same conditions as in Example 1, except that the rotary kiln reactor was heated at a heating rate of 6° C./min to 500° C. and the heat treatment process was carried out for 200 minutes.

Example 4
In Example 1, the reaction was carried out under the same conditions as in Example 1, except that the heat treatment process was carried out by applying a multi-stage heating process to the rotary kiln type reactor. Specifically, the first heat treatment process was carried out by heating to 100°C at a heating rate of 1°C/min and maintaining it for 50 minutes. Then, the second heat treatment process was carried out by heating to 250°C at a heating rate of 0.9°C/min and maintaining it for 150 minutes. Then, the second heat treatment process was carried out by heating to 500°C at a heating rate of 0.75°C/min and maintaining it for 200 minutes.

Comparative Example 1
The reaction was carried out under the same conditions as in Example 1, except that the high-boiling wax components of the pyrolysis gas produced in the rotary kiln reactor were not separated and re-supplied, and the refined oil was immediately recovered in a recovery tank via a condenser.

Comparative Example 2
In Example 1, the reaction was carried out under the same conditions as in Example 1, except that domestic waste plastic pellets were used instead of waste plastic pyrolysis oil as the raw material fed into the rotary kiln reactor. Specifically, 500 g of domestic waste plastic pellets of Example 1 were fed into the rotary kiln reactor and then subjected to a heat treatment process. 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 was heated to 500°C at a heating rate of 0.75°C/min, and the heat treatment process was carried out for 200 minutes. Only pyrolysis gas components were recovered from the product of the heat treatment process and supplied to a gas separator. In the gas separator, high boiling point wax components contained in the pyrolysis gas components were separated into the lower part of the gas separator, and the separated high boiling point wax components were re-supplied once to the rotary kiln reactor through a re-supply line connected from the lower part of the gas separator to the inlet of the rotary kiln reactor, and the heat treatment process was repeated. Finally, the pyrolysis gas from which the high boiling point wax components had been removed was recovered at the top of the gas separator, passed through a condenser, and the waste plastic pyrolysis oil was recovered in a recovery tank.

[Evaluation example]
[Effect of removing impurities]
The chlorine, nitrogen, sulfur, and oxygen contents of the raw material and the resulting refined oil were measured by ICP and XRF analysis, and the effect of removing impurities was evaluated.

[Lightweight effect]
The naphtha and KERO components contained in the feedstock and refined oil were quantified by gas chromatography (ASTM D86), and the combined weight was measured to evaluate the degree of lightening.
The analysis results are shown in Table 1 below.

[Interpretation of results]
As shown in Table 1, in all of Examples 1 to 4 according to the present disclosure, it can be confirmed that impurities such as chlorine, nitrogen, sulfur, and oxygen can be effectively reduced from the waste plastic pyrolysis oil feedstock, and refined oil having an increased content of light fractions (naphtha and KERO) can be obtained.

In detail, in Example 2, it can be confirmed that by adding the Cu/CaO additive to a rotary kiln type reactor and carrying out a heat treatment process, the effect of reducing the impurities chlorine, nitrogen, sulfur, and oxygen and the effect of lightening the material are the most excellent.

In Example 3, the rotary kiln reactor is heated at a rate of 6°C/min for the heat treatment process, and the reduction effect of impurities such as chlorine, nitrogen, sulfur, and oxygen and the lightening effect are slightly lower than in Example 1, but it can be confirmed that the result is superior to Comparative Examples 1 and 2.

In Example 4, by applying a multi-stage heating process to the rotary kiln-type reactor and carrying out the heat treatment process, it can be confirmed that the effect of reducing the impurities chlorine, nitrogen, sulfur, and oxygen and the effect of lightening the product are even better than in Example 1.

In Comparative Example 1, the process of separating and resupplying the high-boiling wax components of the pyrolysis gas generated from the rotary kiln reactor is not performed, and it can be confirmed that the effect of reducing the impurities chlorine, nitrogen, sulfur, and oxygen and the effect of lightening the gas are significantly low.

In Comparative Example 2, since pellets of waste plastic from daily use are used as the reaction raw material instead of waste plastic pyrolysis oil, it can be confirmed that the effect of reducing the impurities chlorine, nitrogen, sulfur, and oxygen and the effect of lightening the material are significantly low.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and may be manufactured in various different forms, and a person having ordinary knowledge in the technical field to which the present invention belongs can understand that the present invention can be embodied in other specific forms without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting.

1: Waste plastic pyrolysis oil raw material, 2: Gas components, 3: High boiling point wax components, 4: Light gas components, 5: Solid components, 6: Waste plastic, 10: Refined oil, 100: Rotary kiln type reactor, 200: Gas separator, 300: Condenser, 400: Pyrolysis reactor

Claims (18)

A step of charging a waste plastic pyrolysis oil raw material into a rotary kiln type reactor and heating the rotary kiln type reactor to heat-treat the waste plastic pyrolysis oil raw material (S1);
A step (S2) of recovering a gas component from the product of the step (S1);
A step (S3) of 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 type reactor of the step (S1);
A step (S4) of recovering a refined oil from the gas component from which the high boiling point wax component has been removed;
A method for refining waste plastic pyrolysis oil, comprising: The method for refining waste plastic pyrolysis oil according to claim 1, wherein the waste plastic pyrolysis oil raw material is a liquid pyrolysis oil containing naphtha: 10-30 wt%, KERO: 20-30 wt%, LGO: 10-30 wt%, and VGO: 30-50 wt%. The method for refining waste plastic pyrolysis oil according to claim 1, wherein the (S1) step heats the rotary kiln reactor to a third temperature for heat treatment. The method for refining waste plastic pyrolysis oil according to claim 3, wherein the third temperature is 400 to 600°C. The method for refining waste plastic pyrolysis oil according to claim 3, wherein in step (S1), the rate of temperature rise to the third temperature is 0.5°C/min to 5°C/min. Before the step (S1),
A step of heating the rotary kiln reactor to a first temperature and subjecting the waste plastic pyrolysis oil raw material to a first heat treatment (S1-1);
The rotary kiln reactor is heated to a second temperature to subject the waste plastic pyrolysis oil raw material to a second heat treatment (S1-2);
The method for refining waste plastic pyrolysis oil according to claim 3, further comprising: heating the rotary kiln reactor from the first temperature to the third temperature in sequence, the temperature of the rotary kiln reactor being increased by heating the rotary kiln reactor from the first temperature to the third temperature in sequence. The method for refining waste plastic pyrolysis oil according to claim 6, wherein the first temperature is 50 to 150°C. The method for refining waste plastic pyrolysis oil according to claim 6, wherein the second temperature is 220 to 300°C. The method for refining waste plastic pyrolysis oil according to claim 1, wherein the heat treatment in step (S1) is carried out by adding an additive. The method for refining waste plastic pyrolysis oil according to claim 9, wherein the additive includes a metal oxide catalyst or a composite catalyst in which an active metal is supported on a metal oxide carrier. Before the step (S1),
The method for refining waste plastic pyrolysis oil according to claim 1, further comprising the step of (S0) charging waste plastic into a pyrolysis reactor and pyrolyzing it at a temperature of 300 to 600 ° C. in a non-oxidizing atmosphere to produce a waste plastic pyrolysis oil raw material. The method for refining waste plastic pyrolysis oil according to claim 11, wherein the pyrolysis reactor in step (S0) includes a rotary kiln type reactor. The method for refining waste plastic pyrolysis oil according to claim 1, wherein the refined oil recovered in step (S4) has a chlorine content reduced by 50% or more compared to the waste plastic pyrolysis oil feedstock in step (S1). The method for refining waste plastic pyrolysis oil according to claim 1, wherein the refined oil recovered in step (S4) has nitrogen, sulfur, and oxygen contents each reduced by 20% or more compared to the waste plastic pyrolysis oil feedstock in step (S1). The method for refining waste plastic pyrolysis oil according to claim 1, wherein the ratio of the light fraction of the refined oil recovered in step (S4) to the light fraction of the waste plastic pyrolysis oil feedstock in step (S1) is 1.3 or more by weight. A rotary kiln type reactor configured to receive a waste plastic pyrolysis oil feedstock;
a gas separator configured to receive gas components from the rotary kiln-type reactor;
a condenser configured to receive a light gas component from the gas separator;
a re-supply line configured to re-supply the high boiling point wax component separated in the gas separator to the rotary kiln type reactor;
The waste plastic pyrolysis oil refining equipment includes: The waste plastic pyrolysis oil refining apparatus according to claim 16, wherein the rotary kiln type reactor includes a first region, a second region, and a third region in sequence from the raw material inlet to the discharge outlet. The waste plastic pyrolysis oil refining apparatus according to claim 16, wherein the rotary kiln type reactor includes a batch type reactor.

Images