Apparatus and method for purifying pyrolysis product, and system and method for producing petrochemical product

Abstract

To provide a technique capable of purifying a thermal decomposition product obtained from a waste plastic to a level capable of being supplied to an ethylene apparatus.SOLUTION: The apparatus 1 for purifying a pyrolysis product includes a deaerator 10 for deaerating waste plastic, a pyrolysis furnace 12 for pyrolyzing the deaerated waste plastic to produce a pyrolysis gas, a condenser 15 for condensing the pyrolysis gas to produce a light gas and an oil-water mixture, an oil-water separator 19 for separating the oil-water mixture into oil and water, a first impurity removing device 23 for removing impurities including at least acidic gas from the light gas to produce a pyrolysis purified gas, and a second impurity removing device 31 for removing impurities including at least organic chlorine from the oil to produce a pyrolysis purified oil.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for purifying pyrolysis products used in a petrochemical product (e.g., gas, oil) production system, and more particularly to a technique for purifying pyrolysis products supplied to an ethylene unit. [Background technology]

[0002] Ethylene units are facilities that produce petrochemical products such as ethylene, propylene, and BTX (benzene, toluene, and xylene) by thermally cracking and separating hydrocarbons. Feedstocks for petrochemical products include ethane, LPG, naphtha, kerosene, and diesel, but naphtha is the main feedstock used in Japan.

[0003] The process in an ethylene unit consists of a thermal cracking process and a separation and purification process. In the thermal cracking process, a mixture of hydrocarbons and steam supplied to a steam cracker (cracking furnace) is thermally cracked in a reaction tube. In the separation and purification process, the thermal cracking fraction is separated and purified into petrochemical products using a distillation column and a reactor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2007-504292 Summary of the Invention [Problem to be solved by the invention]

[0005] The thermal cracking of naphtha requires a large amount of energy, and there is a demand for equipment and technology that reduces energy consumption. In particular, in ethylene units, which are the main equipment in petrochemical production systems, approximately 50% of the energy required for operation is consumed in the thermal cracking process in the steam cracker. Technology has been proposed to convert waste plastics into naphtha (petrochemical feedstock) or ethylene, propylene, and BTX (petrochemical products) by thermal cracking, but in terms of ultimately producing petrochemical products, producing petrochemical products is more energy-efficient than using petrochemical feedstocks because the thermal cracking process is a single step.

[0006] However, pyrolysis products obtained from the thermal decomposition of waste plastics contain impurities that are undesirable for the ethylene unit. This may compromise the safety of the ethylene unit. Specifically, this may result in the generation of explosive substances, which may damage the ethylene unit, or the release of flammable gases. In addition, there is a concern that the catalytic performance of the reactor may be reduced due to the inclusion of poisonous substances. Furthermore, the inclusion of impurities may result in a deterioration in the quality of petrochemical products.

[0007] Therefore, the present invention provides a technology that can refine pyrolysis products obtained from waste plastics to a level that allows them to be supplied to an ethylene unit, and also provides a technology that can produce petrochemical products with excellent raw material cost and energy efficiency by supplying such purified pyrolysis products to an ethylene unit. [Means for solving the problem]

[0008] In one aspect, a pyrolysis product purification apparatus is provided, which includes a degassing device that degasses waste plastics, a pyrolysis furnace that generates pyrolysis gas by thermally decomposing the degassed waste plastics, a condensation device that condenses the pyrolysis gas to generate a light gas and an oil-water mixture, an oil-water separator that separates the oil-water mixture into oil and water, a first impurity removal device that removes impurities containing at least acidic gases from the light gas to generate a pyrolysis purified gas, and a second impurity removal device that removes impurities containing at least organic chlorine from the oil to generate a pyrolysis purified oil.

[0009] In one embodiment, the purification unit further includes an alkaline scrubber that removes acid gases from the light gas produced by the condenser by contacting the light gas with alkaline water. In one embodiment, the condensation device has an oil scrubber and an alkali washing tower, and the refining device further includes a heavy oil transfer line that sends heavy oil discharged from the oil scrubber to the second impurity removal device, and the second impurity removal device is configured to produce the pyrolysis refined oil by removing impurities including at least organic chlorine from the light oil from the oil-water separator and the heavy oil.

[0010] In one embodiment, the pyrolysis furnace is a fluidized bed furnace, and the fluidized bed furnace has the pyrolysis furnace and a medium regeneration furnace through which a fluidized medium circulates. In one embodiment, the purification device further includes a solid-gas separator disposed between the pyrolysis furnace and the condenser, which separates particles from the pyrolysis gas discharged from the pyrolysis furnace.

[0011] In one aspect, a petrochemical product production system is provided, comprising: a purification apparatus for pyrolysis products; an ethylene unit for producing petrochemical products; a pyrolysis purified gas supply line for supplying the pyrolysis purified gas produced by the purification apparatus to the ethylene unit; and a pyrolysis purified oil supply line for supplying the pyrolysis purified oil produced by the purification apparatus to the ethylene unit, wherein the ethylene unit comprises a steam cracker and a separation and purification apparatus, the separation and purification apparatus having a fractionation tower disposed downstream of the steam cracker, and the pyrolysis purified gas supply line and the pyrolysis purified oil supply line are connected to a pipe connecting the steam cracker and the fractionation tower or to the fractionation tower.

[0012] In one aspect, there is provided a method for purifying a pyrolysis product, which includes degassing waste plastics using a degassing device, pyrolyzing the degassed waste plastics in a pyrolysis furnace to produce pyrolysis gas, condensing the pyrolysis gas using a condenser to produce a light gas and an oil-water mixture, separating the oil-water mixture into oil and water using an oil-water separator, removing impurities containing at least acidic gases from the light gas using a first impurity removal device to produce a pyrolysis refined gas, and removing impurities containing at least organic chlorine from the oil using a second impurity removal device to produce a pyrolysis refined oil.

[0013] In one embodiment, the condensation device has an oil scrubber and an alkali washing tower, and the heavy oil discharged from the oil scrubber is sent to the second impurity removal device, and impurities containing at least organic chlorine are removed from the light oil from the oil-water separator and the heavy oil to produce the pyrolysis refined oil. In one embodiment, the pyrolysis furnace is a fluidized bed furnace, and the fluidized bed furnace has the pyrolysis furnace and a medium regeneration furnace through which a fluidized medium circulates. In one embodiment, the purification method further includes separating particles from the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator disposed between the pyrolysis furnace and the condenser.

[0014] In one aspect, there is provided a method for producing a petrochemical product, wherein the pyrolysis purified gas and the pyrolysis purified oil are produced by the method for purifying a pyrolysis product, and the pyrolysis purified gas and the pyrolysis purified oil are supplied to an ethylene unit for producing a petrochemical product, the ethylene unit including a steam cracker and a separation and purification unit, the separation and purification unit having a fractionation tower disposed downstream of the steam cracker, and the pyrolysis purified gas and the pyrolysis purified oil are supplied to a pipe connecting the steam cracker and the fractionation tower or to the fractionation tower. [Effects of the Invention]

[0015] The first impurity removal unit and the second impurity removal unit can remove impurities (e.g., heteroatom compounds) from the light gas and oil (heavy oil, light oil) to produce a pyrolysis purified product (i.e., a pyrolysis purified gas and a pyrolysis purified oil from which impurities have been removed) suitable for an ethylene unit. The resulting pyrolysis purified product is supplied to a supply point located downstream of the steam cracker and used in the production of petrochemical products. As a result, raw material costs for the production of petrochemical products can be reduced and the energy efficiency of the production of petrochemical products can be improved. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram illustrating an embodiment of a petrochemical production system. [Figure 2] FIG. 1 is a schematic diagram illustrating one embodiment of an ethylene unit. [Figure 3] FIG. 1 is a schematic diagram illustrating another embodiment of a petrochemical product production system. [Figure 4] FIG. 10 is a schematic diagram illustrating yet another embodiment of a petrochemical product production system. [Figure 5] FIG. 10 is a schematic diagram illustrating yet another embodiment of a petrochemical product production system. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing one embodiment of a petrochemical product production system. As shown in FIG. 1, the petrochemical product production system includes a thermal cracking product refinement unit 1 and an ethylene unit 2 that produces petrochemical products. Naphtha, liquefied petroleum gas (LPG), or the like is used as a feedstock for the ethylene unit 2. The ethylene unit 2 includes a steam cracker 5 and a separation and purification unit 6. The separation and purification unit 6 has at least a fractionation column 7 arranged downstream of the steam cracker 5. The fractionation column 7 is arranged immediately downstream of the steam cracker 5. The ethylene unit 2, including the steam cracker 5 and the separation and purification unit 6, will be described in detail below.

[0018] The pyrolysis product refinement device 1 is a device that generates pyrolysis gas, which is a pyrolysis product, by thermally decomposing waste plastics, which are raw materials, and further refines the gas and oil contained in the pyrolysis gas. Specific examples of waste plastics include PS (polystyrene), PP (polypropylene), PE (polyethylene), PVC (polyvinyl chloride), and PET (polyethylene terephthalate).

[0019] The refining apparatus 1 is equipped with a degassing apparatus 10 that degasses waste plastics, which are the raw material for the pyrolysis products. The degassing apparatus 10 is a device for removing air (nitrogen, oxygen, argon, etc.) from waste plastics. Specific examples of the degassing apparatus 10 include a volume reduction apparatus that melts waste plastics by heating them, and a steam displacement apparatus that supplies steam to the waste plastics to replace the air present around the waste plastics with steam. However, the degassing apparatus 10 is not limited to these examples as long as it is capable of removing air from the waste plastics.

[0020] The refining apparatus 1 is equipped with a pyrolysis furnace 12 that generates pyrolysis gas by thermally decomposing the degassed waste plastics. The pyrolysis furnace 12 is connected to the degassing device 10 and is arranged downstream of the degassing device 10. The degassed waste plastics are transferred from the degassing device 10 to the pyrolysis furnace 12. The type of the pyrolysis furnace 12 is not particularly limited, and may be, for example, a fluidized bed pyrolysis furnace, which will be described later, or a kiln pyrolysis furnace.

[0021] When the pyrolysis furnace 12 is a fluidized bed pyrolysis furnace, steam is supplied into the pyrolysis furnace 12 as a fluidizing gas, and when the pyrolysis furnace 12 is a kiln-type pyrolysis furnace, steam is supplied into the pyrolysis furnace 12 as a purge gas. The reason for using steam as a fluidizing gas or a purge gas is that light gas and water can be easily separated by subsequent cooling. When light gas is not recovered, the light gas may be used as a fluidizing gas or a purge gas.

[0022] The refining apparatus 1 includes a condenser 15 that condenses the pyrolysis gas to produce a light gas and an oil-water mixture. The condenser 15 is connected to the pyrolysis furnace 12 and is arranged downstream of the pyrolysis furnace 12. The pyrolysis gas is transferred from the pyrolysis furnace 12 to the condenser 15. Specific examples of the condenser 15 include a gas-liquid contact condenser that brings the pyrolysis gas into contact with a cooling liquid (e.g., water or oil), and a heat exchange condenser that brings the pyrolysis gas into contact with a pipe through which a cooling medium flows. However, the condenser 15 is not limited to these examples, as long as it can condense the pyrolysis gas to produce a light gas and an oil-water mixture.

[0023] In this embodiment, the condenser 15 produces a light gas and an oil-water mixture by cooling the pyrolysis gas at, for example, 600°C to 40°C. The oil-water mixture is a mixture of oil and water. In this embodiment, the oil contained in the oil-water mixture is light oil and heavy oil. In other embodiments, the condenser 15 may be configured to cool (condense) the pyrolysis gas in multiple stages.

[0024] The refining apparatus 1 includes an oil-water separator 19 that separates the oil-water mixture into oil and water. The oil-water separator 19 is connected to the condenser 15 and is disposed downstream of the condenser 15. The oil-water mixture is transferred from the condenser 15 to the oil-water separator 19. The purification device 1 brings alkaline water into contact with light gas to purify acid gases (HCl, H2S, HCN, SO X ,NO X The light gas is transferred from the condenser 15 to the alkaline scrubber 20. The alkaline scrubber 20 is connected to the condenser 15 and is disposed downstream of the condenser 15. The light gas is transferred from the condenser 15 to the alkaline scrubber 20.

[0025] The refining unit 1 is equipped with a first impurity removal unit 23 that removes impurities, including at least acid gases, from the light gas to produce a pyrolysis purified gas. The first impurity removal unit 23 is connected to the alkali scrubber 20 and is arranged downstream of the alkali scrubber 20. The light gas is sent from the alkali scrubber 20 to the first impurity removal unit 23. The first impurity removal unit 23 is a unit for removing impurities in the gas that are not suitable for the production of petrochemical products in the ethylene unit 2. Examples of impurities contained in the light gas include acid gases (HCN, NO), and the like. X These include organic compounds (organic chlorine, organic sulfur, etc.), mercury (Hg), and arsenic (As).

[0026] The first impurity removal device 23 includes at least one adsorbent that adsorbs the impurities. An example of an adsorbent is functional activated carbon. The type of adsorbent used is selected based on the type of impurities to be removed. In one embodiment, the first impurity removal device 23 includes multiple adsorbents that can adsorb different types of impurities. As the light gas passes through the adsorbents, the impurities in the light gas are removed by the adsorbents. As a result, a pyrolysis-purified gas, which is a light gas from which impurities have been removed, is obtained.

[0027] The purification system 1 includes a pyrolysis purified gas supply line 25 that supplies the pyrolysis purified gas generated by the first impurity removal system 23 to the ethylene unit 2, a first concentration measuring device 26 that measures the concentration of impurities contained in the pyrolysis purified gas, a first flow path switching valve 27 connected to the pyrolysis purified gas supply line 25, and a pyrolysis purified gas discharge line 28 connected to the first flow path switching valve 27. The first concentration measuring device 26 is disposed downstream of the first impurity removal system 23 and attached to the pyrolysis purified gas supply line 25.

[0028] The first flow path switching valve 27 is configured to selectively communicate the pyrolysis purified gas generated in the first impurity removal device 23 with either the ethylene device 2 or the pyrolysis purified gas discharge line 28. Specific examples of the first flow path switching valve 27 include a three-way valve or a combination of multiple valves. In one example, the first flow path switching valve 27 is an actuator-driven valve. The first flow path switching valve 27 is electrically connected to the first concentration measuring device 26 and is configured to operate based on the measured value of the impurity concentration obtained by the first concentration measuring device 26.

[0029] Specifically, when the measured impurity concentration exceeds the first threshold value, the first flow path switching valve 27 cuts off communication between the first impurity removal device 23 and the ethylene unit 2 and connects the first impurity removal device 23 to the pyrolysis purified gas discharge line 28. As a result, the pyrolysis purified gas with a high impurity concentration is not sent to the ethylene unit 2 but is sent to the pyrolysis purified gas discharge line 28.

[0030] In one embodiment, the pyrolysis purified gas discharge line 28 is connected to an incineration device (not shown), and the pyrolysis purified gas having a high concentration of impurities is incinerated in the incineration device. Since the pyrolysis purified gas having a high concentration of impurities is not sent to the ethylene unit 2, the incorporation of impurities into the ethylene unit 2 is prevented.

[0031] The refining unit 1 includes a second impurity removal unit 31 that removes impurities, including at least organic chlorine, from the oil to produce a pyrolysis refined oil. The second impurity removal unit 31 is connected to the oil-water separator 19 and is located downstream of the oil-water separator 19. The oil is sent from the oil-water separator 19 to the second impurity removal unit 31. The second impurity removal unit 31 is a unit for removing impurities in the oil that are not suitable for the production of petrochemical products in the ethylene unit 2. In the present embodiment shown in FIG. 1 , the oil sent from the oil-water separator 19 to the second impurity removal unit 31 includes light oil and heavy oil.

[0032] The second impurity removal device 31 includes at least one adsorbent that adsorbs the impurities. An example of an adsorbent is functional activated carbon. The type of adsorbent used is selected based on the type of impurities to be removed. In one embodiment, the second impurity removal device 31 includes multiple adsorbents that can adsorb different types of impurities. As the oil passes through the adsorbents, the impurities in the oil are removed by the adsorbents. As a result, pyrolysis refined oil, which is oil from which impurities have been removed, is obtained.

[0033] The refining device 1 includes a pyrolysis refined oil supply line 34 that supplies the pyrolysis refined oil produced by the second impurity removal device 31 to the ethylene device 2, a second concentration measuring device 35 that measures the concentration of impurities contained in the pyrolysis refined oil, a second flow path switching valve 36 connected to the pyrolysis refined oil supply line 34, and a pyrolysis refined oil discharge line 38 connected to the second flow path switching valve 36. The second concentration measuring device 35 is disposed downstream of the second impurity removal device 31 and attached to the pyrolysis refined oil supply line 34.

[0034] The second flow path switching valve 36 is configured to selectively communicate the pyrolysis refined oil produced in the second impurity removal device 31 with either the ethylene device 2 or the pyrolysis refined oil discharge line 38. Specific examples of the second flow path switching valve 36 include a three-way valve or a combination of multiple valves. In one example, the second flow path switching valve 36 is an actuator-driven valve. The second flow path switching valve 36 is electrically connected to the second concentration measuring device 35 and is configured to operate based on the measured value of the impurity concentration obtained by the second concentration measuring device 35.

[0035] Specifically, when the measured impurity concentration exceeds the second threshold value, the second flow path switching valve 36 cuts off communication between the second impurity removal device 31 and the ethylene unit 2 and connects the second impurity removal device 31 to the pyrolysis refined oil discharge line 38. As a result, pyrolysis refined oil with a high impurity concentration is not sent to the ethylene unit 2 but is sent to the pyrolysis refined oil discharge line 38.

[0036] In one embodiment, the pyrolysis refined oil discharge line 38 is connected to an incineration device (not shown), and pyrolysis refined oil with a high concentration of impurities is incinerated in the incineration device. Since pyrolysis refined oil with a high concentration of impurities is not sent to the ethylene unit 2, impurities are prevented from entering the ethylene unit 2.

[0037] The pyrolysis purified gas supply line 25 and the pyrolysis purified oil supply line 34 are connected to the ethylene unit 2 at a position downstream of the steam cracker 5. More specifically, the pyrolysis purified gas supply line 25 and the pyrolysis purified oil supply line 34 are connected to a pipe 40 connecting the steam cracker 5 and the fractionation tower 7, or to the fractionation tower 7. Therefore, the pyrolysis purified gas and pyrolysis purified oil produced by the purification unit 1 are supplied to the pipe 40 connecting the steam cracker 5 and the fractionation tower 7, or to the fractionation tower 7.

[0038] The reason why the supply points of the pyrolysis refined gas and pyrolysis refined oil are located downstream of the steam cracker 5 is as follows. The pyrolysis refined gas and pyrolysis refined oil (hereinafter collectively referred to as pyrolysis refined products) obtained from waste plastics have a wide boiling point range, and the pyrolysis refined products contain heavy fractions and unsaturated compounds. If the pyrolysis refined products are supplied upstream of the steam cracker 5, there is a risk of coking of the radiant tube of the steam cracker 5. The pyrolysis purified product obtained from waste plastic contains trace amounts of basic gases such as NH3. If the pyrolysis purified product is supplied downstream of the cooling tower installed downstream of the fractionation tower 7, the acid water washing process in the cooling tower will be bypassed, and the basic gases cannot be removed. It is important that the distillation separation of the gas and oil contained in the pyrolysis purified product obtained from waste plastics and the cleaning of the gas are carried out using the same separation and cleaning processes as those used for the pyrolysis purified product obtained in the steam cracker 5.

[0039] As described above, the first impurity removal unit 23 and the second impurity removal unit 31 can remove impurities (e.g., heteroatom compounds) from light gas and oil (heavy oil, light oil) to produce a pyrolysis purified product (i.e., a pyrolysis purified gas and pyrolysis purified oil from which impurities have been removed) suitable for the ethylene unit 2. The obtained pyrolysis purified product is supplied to a supply point located downstream of the steam cracker 5 and used in the production of petrochemical products. As a result, raw material costs for the production of petrochemical products can be reduced, and the energy efficiency of the production of petrochemical products can be improved.

[0040] In particular, since pyrolysis of waste plastics can produce pyrolysis refined gases such as lower olefins and pyrolysis refined oils such as BTX, raw material costs and environmental impact can be significantly reduced compared to the petrochemical feedstocks naphtha or LPG. Compared to a process in which pyrolysis oil obtained from waste plastics is supplied to the upstream side of the steam cracker 5 as a petrochemical feedstock, there is only one pyrolysis step, so energy costs can be significantly reduced. By installing the waste plastic pyrolysis furnace 12 and associated facilities next to the ethylene unit 2, it is expected that chemical recycling of waste plastics will be promoted and expanded.

[0041] The yield balance between the pyrolysis purified gas (e.g., lower olefins) and pyrolysis purified oil (e.g., BTX), which are pyrolysis purified products produced by the refining device 1, can be adjusted by the operating conditions of the pyrolysis furnace 12. For example, to increase the yield of pyrolysis purified gas, the pyrolysis temperature in the pyrolysis furnace 12 is set to a temperature higher than 600°C, and to increase the yield of pyrolysis purified oil, the pyrolysis temperature in the pyrolysis furnace 12 is set to a temperature lower than 600°C.

[0042] FIG. 2 is a schematic diagram illustrating one embodiment of an ethylene unit 2. The ethylene unit 2 is an apparatus for producing petrochemical products such as ethylene, ethane, methane, propylene, propane, and gasoline. As shown in FIG. 2, the ethylene unit 2 of this embodiment includes a steam cracker 5, a fractionator 7, a cooling tower 42, a cracked gas compressor 43, a caustic soda wash tower 44, a hydrogen separation step 45, a demethanizer 46, a deethanizer 47, an acetylene hydrogenation reactor 48, an ethylene fractionator 49, a depropanizer 50, a C3 hydrogenation reactor 51, a propylene fractionator 52, a debutanizer 53, and a naphtha hydrogenation reactor 54. The ethylene unit 2 itself has a known configuration, as disclosed in Patent Document 1 (Japanese Patent Publication No. 2007-504292). Therefore, a detailed description of the ethylene unit 2 will be omitted.

[0043] Figure 3 is a schematic diagram showing another embodiment of a petrochemical product manufacturing system. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Figures 1 and 2, so duplicated descriptions will be omitted. The condenser 15 has an oil scrubber 60 and an alkali washing tower 61. The oil scrubber 60 is disposed downstream of the pyrolysis furnace 12 and connected to the pyrolysis furnace 12. The alkali washing tower 61 is disposed downstream of the oil scrubber 60 and connected to the oil scrubber 60. The oil-water separator 19 is disposed downstream of the alkali washing tower 61 and connected to the alkali washing tower 61.

[0044] The oil scrubber 60 cools the recovered heavy oil at its bottom and then sprays the heavy oil into the pyrolysis gas, thereby cooling the pyrolysis gas and condensing the gaseous oil components in the pyrolysis gas to produce gas and heavy oil. In one example, the oil scrubber 60 condenses oil components with a boiling point of 150°C or higher. The condensed oil and the sprayed oil are discharged from the oil scrubber 60 as heavy oil. In one embodiment, oil supplied from an external source may be sprayed in the oil scrubber 60 instead of the recovered heavy oil. The gas separated from the heavy oil is sent from the oil scrubber 60 to the alkali wash tower 61. In the embodiment shown in FIG. 3, the gas sent from the oil scrubber 60 to the alkali wash tower 61 contains moisture and gaseous light oil.

[0045] There are no particular limitations on the specific configuration of the oil scrubber 60 used, and any known oil scrubber can be used. For example, the oil scrubber 60 can be a washing tower having a gas passage formed therein and spray nozzles for spraying oil into the gas flowing through the passage.

[0046] The alkaline washing tower 61 brings the gas from the oil scrubber 60 into contact with alkaline water to remove acid gases (HCl, H2S, HCN, SO2) X ,NO Xetc.) are removed from the gas. A light gas and an oil-water mixture are discharged from the alkaline scrubber 61. The oil-water separator 19 is arranged downstream of and connected to the alkaline scrubber 61. The oil-water mixture is discharged from the alkaline scrubber 61 to the oil-water separator 19. In the embodiment shown in FIG. 3 , the oil-water mixture sent from the alkaline scrubber 61 to the oil-water separator 19 is a mixture of light oil and water.

[0047] In this embodiment, the pyrolysis gas discharged from the pyrolysis furnace 12 is cooled (condensed) in two stages: an oil scrubber 60 and an alkali washing tower 61. In one example, the oil scrubber 60 cools the pyrolysis gas at 600°C to 150°C, thereby producing heavy oil and a gas at 150°C. Furthermore, the alkali washing tower 61 brings the gas at 150°C into contact with alkaline water, thereby producing a light gas and an oil-water mixture at 40°C.

[0048] 1, the first impurity removal device 23 is connected to the alkali washing tower 61, and the second impurity removal device 31 is connected to the oil-water separator 19. The refining apparatus 1 of this embodiment further includes a heavy oil transfer line 63 that sends the heavy oil discharged from the oil scrubber 60 to the second impurity removal device 31. The heavy oil transfer line 63 extends from the oil scrubber 60 to the second impurity removal device 31. The second impurity removal device 31 is configured to remove impurities containing at least organic chlorine from the light oil and heavy oil, thereby producing a pyrolysis refined oil.

[0049] The first impurity removal device 23 and the second impurity removal device 31 can remove impurities (e.g., heteroatom compounds) from light gas, light oil, and heavy oil, thereby producing pyrolysis purified products suitable for the ethylene unit 2 (i.e., pyrolysis purified gas and pyrolysis purified oil from which impurities have been removed).

[0050] FIG. 4 is a schematic diagram showing yet another embodiment of a petrochemical product manufacturing system. The configuration and operation of this embodiment, unless otherwise specified, are the same as those of the embodiment described with reference to FIGS. 1 and 2, and therefore redundant description will be omitted. The pyrolysis product refining device 1 includes a fluidized bed furnace 85 that pyrolyzes and combusts waste plastics. The fluidized bed furnace 85 includes a pyrolysis furnace 12 that pyrolyzes the waste plastics and generates pyrolysis gas, and a media regeneration furnace 87 that combusts the residue of the pyrolyzed waste plastics. The pyrolysis furnace 12 in the embodiment shown in FIG. 4 corresponds to the pyrolysis furnace 12 in the embodiment shown in FIGS. 1 and 3.

[0051] The pyrolysis furnace 12 and the media regeneration furnace 87 are formed within a single fluidized bed furnace 85. That is, the interior of the fluidized bed furnace 85 is divided into the pyrolysis furnace 12 and the media regeneration furnace 87 by a partition wall 88. The overall shape of the fluidized bed furnace 85 is not particularly limited, but may be, for example, cylindrical or rectangular. A fluidized medium (e.g., silica sand) is contained within the pyrolysis furnace 12 and the media regeneration furnace 87. To fluidize the fluidized medium, steam and air are supplied as fluidizing gases to the pyrolysis furnace 12 and the media regeneration furnace 87, respectively. Waste plastic, which is the raw material, is supplied to the pyrolysis furnace 12 via a degassing device 10.

[0052] The degassed waste plastics are fed into the pyrolysis furnace 12 while the bed material circulates between the pyrolysis furnace 12 and the media regeneration furnace 87. The waste plastics are heated by the bed material in the pyrolysis furnace 12, pyrolyzed, and then gasified. The waste plastic residue is transported by the bed material to the media regeneration furnace 87. The waste plastic residue is burned in the media regeneration furnace 87 to heat the bed material. The heated bed material moves into the pyrolysis furnace 12 and functions as a heat source within the pyrolysis furnace 12. The fluidized bed furnace 85, in which the bed material circulates within the furnace in this way, is an internal circulating fluidized bed gasification system.

[0053] The purification device 1 further includes a solid-gas separator 90 disposed between the pyrolysis furnace 12 and the condenser 15, which separates particles from the pyrolysis gas discharged from the pyrolysis furnace 12, and a particle passage structure 91 which sends the particles from the solid-gas separator 90 to the media regeneration furnace 87. The solid-gas separator 90 is connected to the pyrolysis furnace 12 and disposed downstream of the pyrolysis furnace 12. The particle passage structure 91 extends from the solid-gas separator 90 to the media regeneration furnace 87.

[0054] The pyrolysis gas discharged from the pyrolysis furnace 12 contains particles such as bed materials. The solid-gas separator 90 is configured to remove the particles from the pyrolysis gas. The particles removed by the solid-gas separator 90 are, for example, particles with a diameter of 10 μm or more. The specific configuration of the solid-gas separator 90 is not particularly limited, but in one embodiment, the solid-gas separator 90 is a cyclone-type solid-gas separator that separates the particles from the pyrolysis gas by centrifugal force.

[0055] The pyrolysis gas generated by the pyrolysis of waste plastics in the pyrolysis furnace 12 is sent to the solid-gas separator 90. Particles contained in the pyrolysis gas are separated from the pyrolysis gas by the solid-gas separator 90. The particles removed by the solid-gas separator 90 are transported by their own weight through a particle passage structure 91 to the media regeneration furnace 87. The specific structure and shape of the particle passage structure 91 are not particularly limited as long as it has particle passages that allow the particles to pass through.

[0056] A catalyst such as a catalytic cracking catalyst or a reforming catalyst may be added to the fluidized medium to increase the yield of pyrolysis refined gas or pyrolysis refined oil in the refining device 1. In this case, the pyrolysis temperature in the pyrolysis furnace 12 can be lowered.

[0057] In one embodiment, the pyrolysis purified gas discharge line 28 and the pyrolysis purified oil discharge line 38 may be connected to a media regeneration furnace 87. When the impurity concentration measured by the first concentration measuring device 26 exceeds a first threshold value, the first flow path switching valve 27 cuts off communication between the first impurity removal device 23 and the ethylene unit 2 and connects the first impurity removal device 23 to the pyrolysis purified gas discharge line 28. As a result, the pyrolysis purified gas with a high impurity concentration is sent to the media regeneration furnace 87 without being sent to the ethylene unit 2.

[0058] When the impurity concentration measured by the second concentration measuring device 35 exceeds the second threshold value, the second flow path switching valve 36 cuts off communication between the second impurity removal device 31 and the ethylene unit 2 and connects the second impurity removal device 31 to the pyrolysis refined oil discharge line 38. As a result, pyrolysis refined oil with a high impurity concentration is not sent to the ethylene unit 2 but is sent to the media regeneration furnace 87.

[0059] Fig. 5 is a schematic diagram showing an embodiment that combines the embodiment shown in Fig. 3 and the embodiment shown in Fig. 4. More specifically, the embodiment shown in Fig. 5 includes a condenser 15 having the oil scrubber 60 and the alkali washing tower 61 shown in Fig. 3, a fluidized bed furnace 85 having the pyrolysis furnace 12 and a media regeneration furnace 87, a solid-gas separator 90 disposed between the pyrolysis furnace 12 and the condenser 15, and a particle passage structure 91 extending from the solid-gas separator 90 to the media regeneration furnace 87.

[0060] According to the embodiment described with reference to Figures 1 to 5, the first impurity removal unit 23 and the second impurity removal unit 31 can remove impurities (e.g., heteroatom compounds) from light gas and oil (light oil, heavy oil) to produce pyrolysis purified products (i.e., pyrolysis purified gas and pyrolysis purified oil from which impurities have been removed) suitable for the ethylene unit 2. The obtained pyrolysis purified products are supplied to a supply point located downstream of the steam cracker 5 and used in the production of petrochemical products. As a result, raw material costs for the production of petrochemical products can be reduced, and the energy efficiency of the production of petrochemical products can be improved.

[0061] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0062] 1. Pyrolysis product purification equipment 2 Ethylene unit 5. Steam crackers 6 Separation and purification equipment 7. Fractionation tower 10 Degassing device 12 Pyrolysis furnace 15 Condenser 19 Oil-water separator 20 Alkaline washing tower 23 First impurity removal device 25 Pyrolysis refined gas supply line 26 1st concentration measuring device 27 First flow path switching valve 28 Pyrolysis refined gas discharge line 31 Second impurity removal device 34 Pyrolysis refined oil supply line 35 Second concentration measuring device 36 Second flow path switching valve 38 Pyrolysis refined oil discharge line 40 Piping 42 Cooling Tower 43 Cracked gas compressor 44 Caustic soda washing tower 45 Hydrogen separation process 46 Demethanizer 47 Deethanizer 48 Acetylene Hydrogenation Reactor 49 Ethylene rectification tower 50 Depropanizer 51 C3 Hydrogenation Reactor 52 Propylene rectification tower 53 Debutanizer 54 Naphtha hydrogenation reactor 60 Oil Scrubber 61 Alkaline washing tower 63 Heavy Oil Transfer Line 85 Fluidized bed furnace 87 Media regeneration furnace 88 Partition Wall 90 Solid-gas separator 91 Particle passage structure

Claims

1. A purification apparatus for pyrolysis products, comprising: a degassing device for degassing waste plastics; a pyrolysis furnace for generating pyrolysis gas by pyrolyzing the degassed waste plastic; a condenser for condensing the pyrolysis gas to produce a light gas and an oil-water mixture; an oil-water separator that separates the oil-water mixture into oil and water; a first impurity removal device that removes impurities including at least acid gases from the light gas to produce a pyrolysis purified gas; A pyrolysis product purification device including a second impurity removal device that removes impurities containing at least organic chlorine from the oil to produce a pyrolysis refined oil.

2. The apparatus for purifying a pyrolysis product according to claim 1, further comprising an alkaline scrubber that removes acidic gases from the light gas by contacting the light gas produced by the condenser with alkaline water.

3. The condensation device includes an oil scrubber and an alkali washing tower, The refining apparatus further includes a heavy oil transfer line that sends the heavy oil discharged from the oil scrubber to the second impurity removal apparatus, The pyrolysis product purification device described in claim 1, wherein the second impurity removal device is configured to produce the pyrolysis refined oil by removing impurities containing at least organic chlorine from the light oil and the heavy oil from the oil-water separator.

4. The pyrolysis furnace is a fluidized bed pyrolysis furnace, The apparatus for purifying a pyrolysis product according to claim 1 , wherein the fluidized bed furnace has the pyrolysis furnace and a medium regeneration furnace in which a fluidized medium circulates.

5. The apparatus for purifying a pyrolysis product according to claim 4, further comprising a solid-gas separator disposed between the pyrolysis furnace and the condenser for separating particles from the pyrolysis gas discharged from the pyrolysis furnace.

6. A purification device for pyrolysis products according to any one of claims 1 to 5; an ethylene unit for producing petrochemical products; a pyrolysis purified gas supply line that supplies the pyrolysis purified gas produced by the purification device to the ethylene unit; a pyrolysis refined oil supply line that supplies the pyrolysis refined oil produced by the refining device to the ethylene unit; The ethylene unit includes a steam cracker and a separation and purification unit; The separation and purification device has a fractionation column arranged downstream of the steam cracker, a thermal cracking refined gas supply line and a thermal cracking refined oil supply line connected to a pipe connecting the steam cracker and the fractionating tower, or connected to the fractionating tower;

7. A method for purifying a pyrolysis product, comprising: The waste plastic is degassed using a degassing device, The degassed waste plastic is thermally decomposed in a pyrolysis furnace to generate pyrolysis gas; The pyrolysis gas is condensed by a condenser to produce a light gas and an oil-water mixture; The oil-water mixture is separated into oil and water using an oil-water separator; removing impurities including at least an acid gas from the light gas using a first impurity removal device to generate a pyrolysis purified gas; A method for purifying a pyrolysis product, comprising removing impurities containing at least organic chlorine from the oil using a second impurity removal device to produce a pyrolysis refined oil.

8. The condensation device includes an oil scrubber and an alkali washing tower, 8. The method for purifying a pyrolysis product according to claim 7, wherein the heavy oil discharged from the oil scrubber is sent to the second impurity removal device, and impurities containing at least organic chlorine are removed from the light oil from the oil-water separator and the heavy oil, thereby producing the pyrolysis refined oil.

9. The pyrolysis furnace is a fluidized bed pyrolysis furnace, The method for purifying a pyrolysis product according to claim 7, wherein the fluidized bed furnace has the pyrolysis furnace and a medium regeneration furnace in which a fluidized medium circulates.

10. 10. The method for purifying a pyrolysis product according to claim 9, further comprising separating particles from the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator disposed between the pyrolysis furnace and the condenser.

11. The pyrolysis purified gas and the pyrolysis purified oil are produced by the method for purifying a pyrolysis product according to any one of claims 7 to 10, supplying the pyrolysis refined gas and the pyrolysis refined oil to an ethylene unit for producing petrochemical products; The ethylene unit includes a steam cracker and a separation and purification unit; The separation and purification device has a fractionation column arranged downstream of the steam cracker, The method for producing petrochemical products, wherein the pyrolysis refined gas and the pyrolysis refined oil are supplied to a pipe connecting the steam cracker and the fractionation tower, or to the fractionation tower.

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