Method for operating an ethylene plant

Abstract

The present invention provides a method for stably operating an ethylene plant that uses waste plastic cracking oil as part of a naphtha cracker feedstock. [Solution] One aspect of the present disclosure relates to a method for operating an ethylene plant, the ethylene plant being a plant that uses waste plastic cracked oil as part of a naphtha cracker feedstock, the method including: performing an operation risk assessment based on component information of the waste plastic cracked oil used as the feedstock and the proportion of the waste plastic cracked oil in the naphtha cracker feedstock; determining at least one of a type and an amount of a chemical agent to be injected into the plant based on the operation risk assessment; and, when using the waste plastic cracked oil for which the operation risk assessment has been performed, injecting the chemical agent into the plant based on the determination.

Description

[Technical field]

[0001] The present disclosure relates to a method for operating an ethylene plant, a method for controlling the injection of chemicals in an ethylene plant, and an apparatus for use therein. [Background technology]

[0002] In Japan, some waste plastics such as PET bottles are reused through material recycling (mechanical recycling), but the majority of waste plastics are incinerated without being separated. According to a 2020 report by the Ministry of the Environment, nearly 70% of waste plastics are thermally recycled or simply incinerated, and the combustion of this waste plastic emits more than 15 million tons of CO2 annually.

[0003] CO2 is a typical example of a greenhouse gas, and Japan has declared that it aims to become carbon neutral by 2050. In 2019, 29.3% (approximately 325 million tons) of Japan's CO2 emissions were emitted from industry and industrial processes, of which 18.6% (approximately 60 million tons) was emitted in the chemical sector, primarily plastics. In this chemical sector, CO2 is emitted not only in the manufacturing process but also in the recycling of waste plastics (thermal recycling). For this reason, in order to achieve carbon neutrality, efforts are being made to reduce CO2 in the chemical sector, primarily plastics.

[0004] In recent years, the importance and social need for plastic recycling has been increasing both in Japan and overseas. For example, Europe has clearly laid out a policy of not incinerating waste plastics, which emits CO2. Also, in Japan, efforts are being made to decompose waste plastics that cannot be recycled and reuse them as raw materials for plastic products (chemical recycling). One method involves pyrolyzing waste plastics to produce pyrolysis oil (Patent Document 1), mixing this pyrolysis oil with naphtha to use it as a naphtha cracker raw material, and producing plastic raw materials (basic raw materials) such as ethylene and propylene. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7258270 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the cracked oil obtained by decomposing waste plastics (waste plastic cracked oil) is used as part of the naphtha cracker raw material, corrosion, gum, and other contaminants that would not have occurred if naphtha alone was used as the raw material occur in each facility of the plant, resulting in problems such as difficulty in stable operation of the plant. One of the reasons for this is that the waste plastics that are the raw material for waste plastic decomposition oil contain many impurities and different materials. Because waste plastic decomposition oil is made from such materials, it is thought that the produced waste plastic decomposition oil contains many impurities and that its properties (composition information) vary greatly depending on the time of production. Another cause is that waste plastic decomposition oil is produced in a factory different from the plant that produces plastic raw materials (basic raw materials). Since the plant that produces plastic raw materials (basic raw materials) generally uses waste plastic decomposition oil produced in another factory, it is difficult for the plant to control the properties of the waste plastic decomposition oil in advance. In order to control the properties of the waste plastic decomposition oil, it is possible to appropriately adjust the type (composition) of the waste plastic used in the production at the waste plastic decomposition oil production plant, or to remove impurities in advance from the waste plastic used as the raw material, but these operations are not realistic because they require a large amount of cost.

[0007] In one aspect, the present disclosure provides a method capable of stably operating an ethylene plant that uses waste plastic cracking oil as part of a naphtha cracker feedstock. [Means for solving the problem]

[0008] The present disclosure relates to, in one aspect, a method for operating an ethylene plant, the ethylene plant being a plant that uses waste plastic cracked oil as part of a naphtha cracker feedstock, the method including: performing an operation risk assessment based on component information of the waste plastic cracked oil used as the feedstock and a ratio of the waste plastic cracked oil in the naphtha cracker feedstock; determining at least one of a type and an amount of a chemical agent to be injected into the plant based on the operation risk assessment; and, when using the waste plastic cracked oil for which the operation risk assessment has been performed, injecting the chemical agent into the plant based on the determination.

[0009] In another aspect, the present disclosure relates to a method for controlling injection of chemicals in an ethylene plant, the method including: performing an operation risk assessment based on component information of waste plastic cracked oil in a naphtha cracker feedstock and a ratio of the waste plastic cracked oil; determining at least one of a type and an amount of a chemical to be injected into the plant based on the operation risk assessment; and injecting a chemical into the plant based on the determination when using the waste plastic cracked oil for which the operation risk assessment has been performed.

[0010] In still another aspect, the present disclosure relates to an apparatus for controlling injection of chemicals in an ethylene plant, the apparatus including a data acquisition unit that acquires component information of waste plastic decomposition oil in a naphtha cracker feedstock, an evaluation unit that performs an operation risk assessment based on the proportion of the waste plastic decomposition oil and the component information of the waste plastic decomposition oil, a decision unit that determines at least one of the type and amount of chemicals to be injected into the plant based on the operation risk assessment, and a control unit that controls injection of chemicals based on the decision of the decision unit. Effect of the Invention

[0011] According to the present disclosure, stable operation can be achieved in an ethylene plant that uses waste plastic cracking oil as part of a naphtha cracker feedstock. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic block diagram showing an example of the configuration of an ethylene plant. [Diagram 2] FIG. 2 is a schematic block diagram showing an example of the configuration of the driving device of the present disclosure. [Diagram 3] FIG. 3 is a flow diagram of one embodiment of the method of operation of the present disclosure. [Figure 4] FIG. 4 is a table showing the results of driving risk assessment in one embodiment of the driving method of the present disclosure. [Diagram 5] FIG. 5 is a flow diagram of one embodiment of a method of operation of the present disclosure. [Figure 6] FIG. 6 is a flow diagram of one embodiment of a method of operation of the present disclosure. [Figure 7] FIG. 7 is a schematic block diagram showing an example of the configuration of the driving device of the present disclosure. [Figure 8] FIG. 8 is a schematic block diagram showing an example of the configuration of an ethylene plant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Ethylene plants usually produce ethylene and other petrochemical products by thermally cracking petroleum-derived naphtha (hydrocarbon) and separating and refining the resulting gas. In recent years, the importance and social need for plastic recycling has increased due to carbon neutrality and the problem of plastic waste, and ethylene plants have also attempted to use waste plastic cracking oil as part of the naphtha cracker feedstock. However, the properties of waste plastic cracking oil and the impurities (pollutants) it contains are not constant but vary greatly, which causes contamination and corrosion in ways that were not previously anticipated in each piece of plant equipment, resulting in problems that make stable plant operation difficult. In addition, in various plants, in consideration of cost reduction and environmental load reduction, it is generally required to prevent fouling and corrosion in each facility with a smaller amount of chemicals. For this reason, chemicals are usually controlled according to the occurrence of fouling / corrosion. However, such chemical control (treatment according to the occurrence of fouling / corrosion) may cause the operation of the plant to become unstable or inefficient, and as a result, the cost required for treatment may become very high. In response to this, the present inventors have conducted extensive research into the relationship between the properties of waste plastic cracking oil and its proportion in the naphtha cracker feedstock and the occurrence of fouling / corrosion, as well as the type of chemicals used and their injection amounts, in an ethylene plant that uses waste plastic cracking oil as part of the naphtha cracker feedstock. In the process, the inventors have found that by evaluating in advance the risks that may affect the operation (stable operation) of the plant, such as fouling / corrosion that may occur due to the use of the waste plastic cracking oil, and controlling the chemicals to be injected in advance based on the risk evaluation, it is possible to prevent sudden troubles and malfunctions that affect operation, and as a result, it is possible to realize stable operation and reduce the overall cost of operation.

[0014] In this disclosure, "stable operation can be achieved" means being able to prevent sudden trouble or malfunction that affects operation. In the present disclosure, "controlling the amount of chemicals to be injected in advance" includes controlling the type and / or amount of chemicals to be injected into the plant (each piece of equipment) based on a risk assessment prior to the occurrence of dirt / corrosion caused by the use of waste plastic decomposition oil, and controlling the type and / or amount of chemicals to be injected into the plant (each piece of equipment) based on a risk assessment so that the occurrence of dirt / corrosion caused by the use of waste plastic decomposition oil can be kept to a level that does not affect the operation (stable operation) of the plant.

[0015] In one aspect, the present disclosure relates to an operation method for an ethylene plant that uses waste plastic cracking oil as part of a naphtha cracker feedstock. The operation method of the present disclosure includes: performing an operation risk assessment based on component information of the waste plastic cracking oil used as a feedstock and the ratio of the waste plastic cracking oil in the naphtha cracker feedstock; determining at least one of the type and amount of a chemical to be injected into the plant based on the risk assessment; and injecting a chemical into the plant based on the determination when using the waste plastic cracking oil that has been risk assessed. According to the operation method of the present disclosure, in one or more embodiments, stable operation of the ethylene plant can be realized even when waste plastic cracking oil is used as part of the naphtha cracker feedstock.

[0016] The ethylene plant in which the operating method of the present disclosure is carried out is an ethylene plant that uses waste plastic cracked oil as part of the naphtha cracker feedstock. In the present disclosure, "naphtha cracker feedstock" refers to a naphtha-containing feedstock that is supplied to a naphtha cracker (also called a naphtha cracking furnace or a heating furnace) that cracks hydrocarbons to produce gases such as ethylene. The naphtha cracker feedstock includes naphtha feedstock and waste plastic cracked oil. In one or more embodiments, naphtha feedstock includes petroleum-derived naphtha and biomass naphtha. In one or more embodiments, waste plastic cracked oil includes pyrolysis oil (waste plastic pyrolysis oil) obtained by pyrolyzing (oilification) waste plastics, and oil (recycled oil) obtained by decomposing (oilification) waste plastics in high-temperature and high-pressure supercritical water. In one or more embodiments, the proportion of waste plastic cracked oil in the naphtha cracker feedstock is not particularly limited, and is about 0.1% by weight to 10% by weight, or 0.1% by weight to 9% by weight, 0.1% by weight to 7% by weight, or 0.1% by weight to 5% by weight.

[0017] In one or more embodiments, the component information of the waste plastic decomposition oil may include chemical properties and physical properties of the waste plastic decomposition oil. In one or more embodiments, the method of the present disclosure may include acquiring component information of the waste plastic decomposition oil. In one or more embodiments, the component information may be acquired by performing a component analysis of the waste plastic decomposition oil to acquire component information, or may be acquired component information that has been measured (acquired) in advance.

[0018] In one or more embodiments, the chemical properties include bromine number, total acid number, total chlorine, and corrosivity. Bromine number is a value representing the mass (g) of bromine that reacts with 100 g of a sample under test conditions (an index showing the amount of sites that react with bromine), and can be measured according to ASTM (American Society of Testing and Materials) D1159. The total acid number is a value representing the mass (mg) of potassium hydroxide required to neutralize all acidic components contained in 1 g of a sample, and can be measured by an acid number test method using potentiometric titration based on ASTM D664. Total chlorine (total chlorides) is the amount of chlorine contained in a sample, and can be measured by combustion microcoulometric titration based on JIS K 2170. Corrosivity can be measured based on a corrosion test according to NACE TM172.

[0019] In one or more embodiments, the chemical properties include impurities (contaminants) in the waste plastic decomposition oil. In one or more embodiments, the impurities include iron, calcium, copper, potassium, magnesium, sodium, silicon, titanium, zinc, nitrogen, chlorine, and oxygen.

[0020] The physical properties, in one or more embodiments, include pour point, viscosity, and specific gravity. Pour point can be measured according to ASTM D97. The viscosity can be measured according to JIS Z 8803. The specific gravity can be measured according to JIS K 2249.

[0021] In one or more embodiments, the "risk assessment of operation" in this disclosure includes evaluating the possibility of occurrence of problems (risks) that may affect operations when using naphtha cracker feedstock containing waste plastic cracking oil. In one or more embodiments, the "problems (risks) that may affect operations" in this disclosure include occurrence of corrosion, occurrence of fouling, adhesion / accumulation of fouling, and deterioration of oil-water separation in a quench water separator (QWS).

[0022] In one or more embodiments, the risk assessment of operation is preferably performed for two or more pieces of equipment in the ethylene plant in order to realize more stable operation. The "equipment" in the present disclosure may include not only equipment included in the ethylene plant (for example, heating furnaces (such as naphtha cracking furnace 11), distillation towers (such as gasoline fractionator 12, demethanizer 16, deethanizer 17, ethylene fractionator 20, depropanizer 18, debutanizer 19, and propylene fractionator 21) shown in FIG. 1 described later, water treatment equipment (such as quench water separator (QWS) 26 and process water stripper (PWS) 27)), and dilution steam generator (Dilution Steam Generator (DSG) 28), but also piping connecting each piece of equipment included in the ethylene plant.

[0023] In one or more embodiments, determining the medication includes determining the medication (e.g., type of medication) to be infused based on the results (contents) of the risk assessment, and determining the amount of the determined medication to be infused. In one or more embodiments, but not limited to, the decision on the medication may include, when the risk of driving is determined (assessed) to be high, making a decision to change the type of medication to be injected and determining the injection amount (concentration) of the determined medication based on the results (contents) of the risk assessment, or may include deciding to increase the amount of medication to be injected (without changing the type of medication to be injected). In one or more embodiments, but not limited to, the drug decision may include making a decision to change the type of drug to be injected and determining the injection amount (concentration) of the determined drug based on the results (contents) of the risk assessment if the risk of driving is determined (assessed) to be low, or may include deciding to maintain or reduce the amount of drug to be injected (without changing the type of drug to be injected).

[0024] In one or more embodiments, the operating method of the present disclosure includes making a drug decision for each piece of equipment that has undergone an operational risk assessment.

[0025] In one or more embodiments, examples of the agent include a corrosion inhibitor, an antifouling agent, an emulsion breaker, etc. In one or more embodiments, the agent to be used can be appropriately determined depending on each facility.

[0026] In one or more embodiments, the operating method of the present disclosure may include determining the proportion of waste plastic cracking oil to be injected into the plant based on an operational risk assessment, and mixing the waste plastic cracking oil with naphtha feedstock (at least one of petroleum-derived naphtha and biomass naphtha) based on the determination.

[0027] The injection of chemicals determined based on the risk assessment of operation will be carried out when using the waste plastic decomposition oil for which the risk assessment has been carried out. In one or more embodiments, "when using waste plastic cracking oil" in the present disclosure includes, in advance of or simultaneously with the waste plastic cracking oil that has been subjected to the risk assessment of operation being supplied to an ethylene plant (e.g., a raw material tank or a naphtha cracking furnace), before or simultaneously with the feed gas containing the gas generated from the raw material containing the waste plastic cracking oil being supplied to each facility constituting the ethylene plant (e.g., the facility for which the risk assessment of operation has been performed), and before or simultaneously with the water (e.g., quench water or its treated water, etc.) mixed with the feed gas containing the gas generated from the raw material containing the waste plastic cracking oil being supplied to the process water treatment facility of the ethylene plant (e.g., the process water treatment facility for which the risk assessment of operation has been performed). By injecting the agent at such a timing, it is possible to prevent sudden troubles or malfunctions that affect the operation, and as a result, it is possible to realize more stable operation and reduced running costs for operation. In one or more embodiments, "supply of waste plastic cracking oil that has undergone an operational risk assessment" may include mixing the waste plastic cracking oil that has undergone an operational risk assessment with naphtha feedstock, and introducing the naphtha cracker feedstock containing the waste plastic cracking oil into a naphtha cracker (heating furnace).

[0028] In one or more embodiments, the injection of the agent determined based on the risk assessment of operation may be carried out simultaneously to a plurality of pieces of equipment included in the ethylene plant, or may be carried out for each piece of equipment.

[0029] In one or more embodiments, the operating method of the present disclosure may include supplying waste plastic decomposition oil that has been subjected to an operational risk assessment, and then injecting an agent determined based on the risk assessment.

[0030] In one or more embodiments, the operating method of the present disclosure may include making a decision to strengthen monitoring of the plant based on a risk assessment, and strengthening the monitoring based on the decision. In one or more embodiments, which are not particularly limited, when it is determined (assessed) that the risk of operation is low but that risk reduction measures need to be implemented as necessary, the content of strengthening the monitoring (e.g., equipment, samples to be taken, etc.) may be determined based on the result (content) of the risk assessment, and monitoring of the content may be strengthened based on the decision. In this disclosure, "monitoring" refers to taking samples (e.g., water and oil) from equipment of an operating plant and analyzing them. In this disclosure, "strengthened monitoring" refers to performing monitoring more frequently than usual, and in one or more embodiments, may include determining problems (risks) that may affect operations based on the monitoring results.

[0031] In another aspect, the present disclosure relates to a method for controlling the injection of a chemical agent in an ethylene plant. The control method of the present disclosure includes: performing an operation risk assessment based on component information of waste plastic cracking oil in a naphtha cracker feedstock and a ratio of the waste plastic cracking oil; determining at least one of the type and amount of a chemical agent to be injected into the plant based on the operation risk assessment; and injecting a chemical agent into the plant based on the determination when using the waste plastic cracking oil for which the operation risk assessment has been performed.

[0032] In one or more embodiments, the control method of the present disclosure may include determining at least one of the type and amount of a chemical to be injected into the ethylene plant based on a risk assessment of operation obtained in advance. Thus, in yet another aspect, the control method of the present disclosure includes determining at least one of the type and amount of a chemical to be injected into the ethylene plant based on a risk assessment obtained based on component information of the waste plastic cracking oil in the naphtha cracker feedstock, and injecting the chemical into the plant based on the determination when the waste plastic cracking oil is used.

[0033] In another aspect, the present disclosure relates to an apparatus for controlling the injection of a chemical agent in an ethylene plant. The apparatus of the present disclosure includes a data acquisition unit that acquires component information of a waste plastic decomposition oil in a naphtha cracker feedstock, an evaluation unit that performs an operation risk evaluation based on the component information of the waste plastic decomposition oil and the ratio of the waste plastic decomposition oil in the feedstock, a decision unit that decides at least one of the type and amount of a chemical agent to be injected into the plant based on the operation risk evaluation, and a control unit that controls the injection of the chemical agent based on the decision of the decision unit.

[0034] In one or more embodiments, the device of the present disclosure may include a storage unit that stores operation data of the plant. In one or more embodiments, the operation data of the plant is data used for risk assessment of operation, and includes information on waste plastic decomposition oil, occurrence of dirt and / or corrosion, and chemicals. In one or more embodiments, the storage unit stores data such as component information of the waste plastic decomposition oil, the ratio of the waste plastic decomposition oil in the naphtha cracker feedstock, the type of chemical and its injection amount, and the occurrence status of dirt and / or corrosion in each facility of the plant (for example, at least one of the facilities 11 to 28 shown in FIG. 1 or 11 to 30 shown in FIG. 8). In one or more embodiments, the storage unit may store a relationship between the ratio of the waste plastic decomposition oil, the type of chemical and its injection amount, and the occurrence status of dirt and / or corrosion in each facility of the plant (for example, at least one of the facilities 11 to 28 shown in FIG. 1 or 11 to 30 shown in FIG. 8) based on the above data.

[0035] In still another aspect, the apparatus of the present disclosure includes a decision unit that decides at least one of the type and amount of a chemical to be injected into the plant based on an operational risk assessment obtained based on component information of waste plastic decomposition oil in the naphtha cracker feedstock, and a control unit that controls the injection of the chemical based on the decision of the decision unit.

[0036] [First embodiment] Fig. 1 is a flow diagram for explaining an example of a flow in an ethylene plant. In one or more embodiments, which are not particularly limited, the operation method of the present disclosure can be carried out in an ethylene plant 100 having the configuration shown in Fig. 1, thereby making it possible to realize stable operation of the plant.

[0037] As shown in FIG. 1, the ethylene plant 100 includes a naphtha cracking furnace (naphtha cracker, furnace) 11, a gasoline fractionator (primary fractionator, also referred to as a gasoline tower) 12, a quench water tower (QWT) tower 13, a cracked gas compressor (charge gas compressor, CGC) 14, a caustic tower 15, a demethanizer tower 16, a deethaner tower 17, a depropanizer tower 18, a debutanizer tower 19, an ethylene fractionator 20, and a propylene fractionator 21, etc.

[0038] The ethylene plant 100 in FIG. 1 includes raw material tanks 22-25. The raw material tanks 23-25 ​​can store petroleum-derived naphtha, biomass naphtha, and waste plastic cracked oil, respectively. The raw material tank 22 is connected to the raw material tanks 23-25. The petroleum-derived naphtha, biomass naphtha, and waste plastic cracked oil are supplied to the raw material tank 22 from the raw material tanks 23-25, respectively, and mixed. The raw material tank 22 is connected to the naphtha cracking furnace 11. The raw materials mixed in the raw material tank 22 are sent to the naphtha cracking furnace 11 through a pipe connecting the raw material tank 22 and the naphtha cracking furnace 11, and are preheated in the naphtha cracking furnace 11 and then mixed with dilution steam generated by a dilution steam generator (DSG) 28. Thereafter, the naphtha is further heated to 750° C. to 850° C. in the naphtha cracking furnace 11 for thermal decomposition, thereby producing a feed gas (cracked gas) containing methane, ethylene, ethane, propane, butane, and the like. The feed gas is cooled in a gasoline fractionator 12 and then further cooled in a quench tower 13 before being fed to a cracked gas compressor (CGC) 14 and then to a caustic wash tower 15 . In the quench tower 13, steam in the feed gas cooled by an associated heat exchanger is condensed and separated, and quench water, which is condensed water of the steam, is recovered from the bottom of the quench tower 13 and supplied to a quench water separator (QWS) 26. The quench water separator (QWS) 26 separates oil from the quench water recovered from the bottom of the quench tower 13. The quench water from which oil has been separated is supplied to a process water stripper (PWS) 27. A cracked gas compressor (CGC) 14 compresses the gas for downstream rectification of the feed gas. A caustic scrubber 15 removes acid gas components (such as hydrogen sulfide and carbon dioxide) contained in the feed gas. The feed gas from which acidic gas components have been removed in the caustic washing tower 15 is separated into each component (methane, ethylene, ethane, propylene, propane, butane, pentane, etc.) by passing through distillation towers such as the demethanizer 16, the deethaneizer 17, the ethylene fractionator 20, the depropanizer 18, the debutanizer 19, and the propylene fractionator 21. The process water stripper (PWS) 27 removes impurities such as hydrocarbons and ammonia contained in the water (quench water) separated in the quench water separator (QWS) 26. The water treated in the process water stripper (PWS) 27 is supplied to a dilution steam generator (DSG) 28 and the like, and is used as dilution steam, etc., for use in the thermal decomposition of the raw material.

[0039] In the ethylene plant 100, the above-mentioned facilities 11-28 and the piping connecting the facilities 11-28 are each provided with a device for injecting a chemical agent, as necessary. The device for injecting a chemical agent may include a chemical agent injection line, a chemical agent injection pump, and the like. Each device for injecting a chemical agent may include a tank for storing the chemical agent. The device for injecting a chemical agent may be provided upstream of the plant (for example, the naphtha cracking furnace 11).

[0040] The chemicals include chemicals capable of acting on failure factors that may occur in the equipment 11 to 28 and piping of the ethylene plant 100. In one or a plurality of embodiments, the chemicals include a corrosion inhibitor, an antifouling agent, an emulsion breaker agent, and the like.

[0041] Each piece of equipment and each pipe may be provided with one or more sensors capable of measuring the flow rate, occurrence of fouling, corrosion status, etc. in each piece of equipment and each pipe. The measurements taken by the sensors may be recorded together with other conditions (e.g., the type of agent and its injection amount, and the property analysis of the waste plastic decomposition oil and its addition ratio), and the information may be used for risk assessment of operation.

[0042] 2 is a schematic block diagram showing the configuration of one embodiment of an apparatus usable in the operating method of the present disclosure. The apparatus 1001 in this embodiment includes a data acquisition unit 1101, an evaluation unit 1102, a decision unit 1103, and a control unit 1104.

[0043] The data acquisition unit 1101 acquires component information of the waste plastic decomposition oil. The component information includes the bromine number, the total acid number, the total chlorine, the corrosivity, the impurities, the pour point, the viscosity, the specific gravity, and the pH.

[0044] The evaluation unit 1102 performs an operation risk assessment based on the component information of the waste plastic cracked oil acquired by the data acquisition unit 1101. The evaluation unit 1102 performs an operation risk assessment according to the addition ratio of the waste plastic cracked oil to the naphtha raw material (petroleum-derived naphtha and biomass naphtha) (ratio of the waste plastic cracked oil) based on the component information of the waste plastic cracked oil and pre-stored plant operation data.

[0045] The determination unit 1103 determines the type and amount of chemical to be injected into the plant based on the risk assessment of operation obtained by the evaluation unit 1102. The determination unit 1103 inputs (collates) the risk assessment of operation obtained by the evaluation unit 1102 into pre-stored chemical injection data, thereby determining the type and injection amount of chemical that enables stable operation.

[0046] The control unit 1104 controls the injection of the drug based on the decision made by the decision unit 1103. The control unit 1104 controls the type of drug to be injected and / or the injection amount of the drug based on the decision made by the decision unit 1103.

[0047] An embodiment of a method for operating an ethylene plant according to the present disclosure will be described. 3 is a flow diagram showing one embodiment of a method for operating an ethylene plant. In this embodiment, an example will be described in which risk assessment of operation is performed when switching over to waste plastic cracking oil, and injection control of chemicals is performed based on the assessment.

[0048] First, the data acquisition unit 1101 acquires component information of the waste plastic decomposition oil to be used (S101). The component information may be acquired by inputting a measured value obtained by measuring the component information of the waste plastic decomposition oil to be used, or may be acquired by inputting component information that has been measured (acquired) in advance.

[0049] Next, the evaluation unit 1102 performs an operation risk assessment based on the additive ratio of the waste plastic cracked oil (ratio of waste plastic cracked oil) to the naphtha feedstock (petroleum-derived naphtha and biomass naphtha) based on the component information of the waste plastic cracked oil and pre-stored plant operation data (S102). The plant operation data may include the properties of the waste plastic cracking oil, the ratio of the waste plastic cracking oil in the naphtha cracker feedstock, the occurrence of dirt / corrosion, the type of chemical agent and its injection amount, etc. The plant operation data preferably includes not only past operation data but also current operation data (type of chemical agent and its injection amount).

[0050] The risk assessment of operation is performed at multiple addition rates (for example, one or more of 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%). By performing the risk assessment of operation at multiple addition rates, it may be possible to quickly change the addition rate of waste plastic decomposition oil and determine the type of agent and its injection amount associated with the change in the addition rate. The risk assessment of operation is performed at least at one or more points in the equipment included in the plant and the piping connecting the equipment. The equipment includes a naphtha cracking furnace 11, a gasoline fractionator 12, a quench tower 13, a cracked gas compressor (CGC) 14, a caustic scrubber 15, a demethanizer 16, a deethanizer 17, a depropanizer 18, a debutanizer 19, an ethylene fractionator 20, a quench water separator (QWS) 26, a process water stripper (PWS) 27, and a dilution steam generator (DSG) 28, as shown in Fig. 1.

[0051] FIG. 4 shows an example of the risk assessment of driving in this embodiment. <Evaluation criteria> A: Almost no risk (low risk). B: Implement risk reduction measures as necessary (strengthen monitoring). C: There is a risk that requires immediate action (high risk). D: There is a risk that requires immediate action (extremely high risk).

[0052] In addition to evaluation based on the above evaluation criteria, the evaluation unit 1102 may predict risks that may occur in each piece of equipment (for example, occurrence of corrosion, occurrence of dirt, adhesion / accumulation of dirt, etc.).

[0053] Next, the determination unit 1103 determines the type and amount of chemical to be injected into each piece of equipment in the plant based on the operation risk assessment obtained by the evaluation unit 1102 and the proportion of waste plastic decomposition oil in the raw material (S103). The determination unit 1103 inputs the operation risk assessment and the proportion of waste plastic decomposition oil into pre-stored chemical injection data to determine the type and injection amount of chemical to be injected that enables stable operation. The decision unit 1103 decides to change the type of drug (to a more effective drug) for equipment (and piping connected to the equipment, if necessary) whose operating risk has been judged to be C or D (high or extremely high risk) by the evaluation unit 1102, or, if the type of drug is not to be changed, decides to supply a greater amount of drug than usual. The decision unit 1103 decides to maintain the amount of drug injected at the same level as normal or to supply a less than normal amount in equipment (and, if necessary, piping connected to the equipment) for which the evaluation unit 1102 has determined that the operation risk assessment is A or B (low risk or enhanced monitoring).

[0054] The determination unit 1103 may determine to strengthen monitoring of equipment (and piping connected to the equipment as necessary) whose operation risk assessment has been determined to be B (strengthened monitoring) by the evaluation unit 1102, in parallel with determining the injection amount of the above-mentioned chemical. The monitoring items can be appropriately determined depending on the equipment, and in one or more embodiments, examples of the monitoring items include chlorine (corrosiveness) and fouling. For example, if the bromine value of waste plastic decomposition oil is high, oxygen may cause the production of gum components, which may increase the fouling load. In such cases, it may be necessary to strengthen monitoring of the fouling load.

[0055] The determination unit 1103 may determine the proportion of waste plastic cracked oil in the naphtha cracker feedstock based on the risk assessment of operation in the assessment unit 1102.

[0056] The control unit 1104 controls devices (pumps) for injecting chemicals, etc., to inject chemicals into each piece of equipment based on the decision made by the decision unit 1103 (S104), and supplies naphtha cracker raw material in which waste plastic cracking oil is mixed with naphtha raw material (petroleum-derived naphtha and biomass naphtha) in the ratio used to decide on the chemicals (S105).

[0057] According to this embodiment, prior to the supply of the waste plastic decomposition oil, a risk assessment of the operation of each facility of the plant is carried out in advance according to the properties of the waste plastic decomposition oil to be used, and an amount of chemicals is injected based on the risk assessment of the operation and the addition ratio of the waste plastic decomposition oil. This makes it possible to prevent sudden troubles and malfunctions that affect the operation, and as a result, it is possible to realize stable operation and reduced running costs for the operation.

[0058] [Second embodiment] In addition to deciding which chemicals to inject based on an operational risk assessment and injecting the chemicals based on that decision, it is also possible to decide to strengthen monitoring (implement risk reduction measures) based on the risk assessment, and to strengthen monitoring based on that decision. This allows the risk of fouling or corrosion to be identified more quickly, which can lead to more stable operation.

[0059] The device 1001 usable in the second embodiment is similar to that in the first embodiment. In the second embodiment, the decision unit 1103 not only determines the chemicals to be injected into the plant based on the risk assessment of operation obtained by the evaluation unit 1102, but also determines whether or not to strengthen monitoring based on the risk assessment.

[0060] Fig. 5 is a flow diagram showing one embodiment of the operation method of the ethylene plant in the second embodiment. In this embodiment, an example will be described in which risk assessment of operation and injection control of chemicals based on the risk assessment are performed when switching over the waste plastic cracking oil.

[0061] First, the data acquisition unit 1101 acquires component information of the waste plastic decomposition oil to be used (S201). Next, the evaluation unit 1102 performs an operation risk assessment based on the additive ratio of the waste plastic cracked oil (ratio of waste plastic cracked oil) to the naphtha feedstock (petroleum-derived naphtha and biomass naphtha) based on the component information of the waste plastic cracked oil and pre-stored plant operation data (S202). S201 and S202 can be performed in the same manner as in the second embodiment.

[0062] Next, the determination unit 1103 judges whether the risk assessment of the operation obtained by the evaluation unit 1102 is A (almost no risk (low risk)) (S203). If it is A, the amount of chemical to be injected into each piece of equipment of the plant is determined based on the ratio of waste plastic decomposition oil in the raw material (S204). The control unit 1104 controls devices (pumps) for injecting chemicals, etc., to inject chemicals into each piece of equipment based on the decision made by the decision unit 1103 (S205), and supplies naphtha cracker raw material in which waste plastic cracking oil is mixed with naphtha raw material (petroleum-derived naphtha and biomass naphtha) in the ratio used to decide on the chemicals (S206).

[0063] If the risk assessment of the operation is not A (S203), the decision unit 1103 judges whether the risk assessment of the operation is B (S207). If it is B, it decides the amount of chemicals to be injected into each piece of equipment of the plant based on the ratio of waste plastic cracking oil in the raw material, and whether to strengthen monitoring (S208). The control unit 1104 injects chemicals based on the decision made by the decision unit 1103 (S205) and supplies naphtha cracker raw material (S206), and increases the frequency of monitoring.

[0064] If the risk assessment of the operation is not B (S207), the decision unit 1103 decides the type and amount of chemicals to be injected into each piece of equipment in the plant based on the ratio of waste plastic cracking oil in the raw material (S209), and decides whether to strengthen monitoring (S210). If it is determined that strengthening of monitoring is necessary, it decides to strengthen monitoring (S211). The control unit 1104 injects chemicals based on the decision made by the decision unit 1103 (S205) and supplies naphtha cracker raw material (S206), and increases the frequency of monitoring. If it is determined that strengthening of monitoring is not necessary (S210), the control unit 1104 injects chemicals based on the decision made by the decision unit 1103 (S205) and supplies naphtha cracker raw material (S206).

[0065] [Third embodiment] Depending on the equipment and the chemicals used, only the amount of chemical to be injected may be determined based on the evaluation of operational risks, without determining (changing) the type of chemical. This makes it unnecessary to switch chemical tanks when changing the type of chemical, and thus allows for simple and rapid response.

[0066] The device 1001 usable in the third embodiment is similar to that in the first embodiment. In the third embodiment, the determination unit 1103 determines the amount of chemical to be injected into the plant based on the risk assessment of operation obtained by the evaluation unit 1102. The determination unit 1103 inputs (collates) the risk assessment of operation obtained by the evaluation unit 1102 into chemical injection data stored in advance, thereby determining the injection amount of chemical that enables stable operation.

[0067] FIG. 6 is a flow diagram showing an embodiment of a method for operating an ethylene plant in the third embodiment.

[0068] In the third embodiment, as shown in FIG. 6, the determination unit 1103 determines the amount of chemical to be injected that enables stable operation by inputting the risk assessment of operation and the proportion of waste plastic decomposition oil into pre-stored chemical injection data (S303). The decision unit 1103 decides to supply a greater than normal amount of drug injection in equipment (and, if necessary, piping connected to the equipment) whose operation risk assessment has been determined to be C or D (high or extremely high risk) by the evaluation unit 1102. The decision unit 1103 decides to maintain the amount of drug injected at the same level as normal or to supply a less than normal amount in equipment (and, if necessary, piping connected to the equipment) for which the evaluation unit 1102 has determined that the operation risk assessment is A or B (low risk or enhanced monitoring).

[0069] In the third embodiment, the determination of the medicine based on the risk assessment (S303) is performed as described above, and the medicine is injected based on this determination, and other operations can be performed in the same manner as in the first embodiment.

[0070] [Fourth embodiment] An apparatus that can be used in the operating method of the present disclosure may include a memory unit that stores operating data of the plant. 7 is a schematic block diagram showing the configuration of one embodiment of an apparatus usable in the operating method of the present disclosure. The apparatus 2001 in this embodiment includes a data acquisition unit 2101, an evaluation unit 2102, a decision unit 2103, a control unit 2104, and a storage unit 2105.

[0071] A data acquisition unit 2101 and a control unit 2104 are similar to the data acquisition unit 1101 and the control unit 1104 of the first embodiment, respectively.

[0072] The storage unit 2105 stores plant operation data to be used for risk assessment of operation. The plant operation data stored in the storage unit 2105 includes component information of waste plastic cracking oil, the ratio of waste plastic cracking oil in naphtha cracker raw material, data on the occurrence of dirt and / or corrosion in each facility of the plant, and data showing the relationship between the type of agent and the injection amount thereof, etc. The storage unit 2105 may store new data obtained by performing machine learning based on the above-mentioned data (data indicating a known relationship) stored in advance and current driving data.

[0073] The evaluation unit 2102 performs an operation risk assessment based on the component information of the waste plastic cracked oil and the plant operation data stored in the memory unit 2105, according to the addition ratio of the waste plastic cracked oil to the naphtha feedstock (petroleum-derived naphtha and biomass naphtha) (ratio of waste plastic cracked oil).

[0074] The determination unit 2103 determines at least one of the type and amount of chemical to be injected into each piece of equipment of the plant based on the operation risk assessment obtained by the evaluation unit 2102, the plant operation data stored in the memory unit 2105, and the proportion of waste plastic decomposition oil in the raw material. The determination unit 2103 inputs the operation risk assessment and the proportion of waste plastic decomposition oil into chemical injection data stored in advance, thereby determining the type of chemical and its injection amount that will enable stable operation.

[0075] [Fifth embodiment] Fig. 8 is a flow diagram for explaining an example of a flow in an ethylene plant. In one or a plurality of embodiments, the operation method of the present disclosure can be carried out in an ethylene plant 200 having the configuration shown in Fig. 8.

[0076] The ethylene plant 200 in FIG. 8 includes raw material tanks 29 and 30. The raw material tank 29 can store petroleum-derived naphtha, and the raw material tank 30 can store waste plastic cracked oil. The raw material tank 29 is connected to the naphtha cracking furnace 11, and the petroleum-derived naphtha supplied from the raw material tank 29 is mixed with the waste plastic cracked oil supplied from the raw material tank 30 through a pipe connecting the raw material tank 29 and the naphtha cracking furnace 11. The mixed raw material is sent to the naphtha cracking furnace 11, preheated in the naphtha cracking furnace 11, and then mixed with diluted steam generated by a dilution steam generator (DSG) 28. After that, the raw material is further heated to 750 to 850 ° C. in the naphtha cracking furnace 11 for thermal decomposition, thereby generating a feed gas (cracked gas) containing methane, ethylene, ethane, propane, butane, and the like.

[0077] The present disclosure further relates to one or more of the following embodiments. [1] A method for operating an ethylene plant, comprising the steps of: The ethylene plant is a plant that uses waste plastic cracking oil as part of a naphtha cracker raw material, The method comprises: Conducting a risk assessment of the operation of the plant based on information on the components of the waste plastic cracking oil used as the raw material and the ratio of the waste plastic cracking oil in the naphtha cracker raw material; determining at least one of the type and amount of chemical to be injected into the plant based on the risk assessment of the operation; and The method includes injecting an agent into the plant based on the determination when using the waste plastic cracking oil after performing the risk assessment of the operation. [2] The method described in [1], wherein the determination of the medication includes increasing the amount of medication to be injected if the driving risk assessment determines that the driving risk is high. [3] The method described in [1] or [2], wherein the determination of the medication includes maintaining or reducing the amount of medication to be injected if the driving risk assessment determines that the driving risk is low. [4] A method according to any one of [1] to [3], wherein the component information of the waste plastic decomposition oil includes at least one of the chemical properties and physical properties of the waste plastic decomposition oil. [5] The method according to [4], wherein the chemical property includes at least one selected from the group consisting of bromine number, total acid number, total chlorine, and corrosivity. [6] The method according to [4] or [5], wherein the physical properties include at least one selected from the group consisting of pour point, viscosity, and specific gravity. [7] The method according to any one of [1] to [6], wherein the operational risk assessment is performed for each of two or more pieces of equipment in the ethylene plant. [8] The method according to any one of [1] to [7], wherein the agent is selected from the group consisting of a corrosion inhibitor, an antifouling agent, and an emulsion breaker. [9] A method for controlling injection of a chemical in an ethylene plant, comprising the steps of: Conduct an operational risk assessment based on the composition information of waste plastic cracking oil in naphtha cracker feedstock and the proportion of waste plastic cracking oil; determining at least one of the type and amount of chemical to be injected into the plant based on the risk assessment of the operation; and The method includes injecting an agent into the plant based on the determination when using the waste plastic cracking oil after performing the risk assessment of the operation.

[10] An apparatus for controlling the injection of chemicals in an ethylene plant, comprising: A data acquisition unit for acquiring component information of waste plastic cracking oil contained in a naphtha cracker feedstock; An evaluation unit that performs an operation risk evaluation based on component information of the waste plastic decomposition oil and the ratio of the waste plastic decomposition oil in the raw material; A determination unit that determines at least one of the type and amount of a chemical to be injected into the plant based on the risk assessment of the operation; and A controller that controls injection of the medication based on a decision of the decision unit.

Claims

1. A method for operating an ethylene plant, comprising the steps of: The ethylene plant is a plant that uses waste plastic cracking oil as part of a naphtha cracker raw material, The method comprises: Conducting an operation risk assessment based on component information of the waste plastic cracking oil used as the raw material and the ratio of the waste plastic cracking oil in the naphtha cracker raw material; determining at least one of the type and amount of chemical to be injected into the plant based on the risk assessment of the operation; and The method includes injecting an agent into the plant based on the determination when using the waste plastic cracking oil after performing the risk assessment of the operation.

2. The method of claim 1 , wherein the medication decision comprises increasing the amount of medication to be infused if the driving risk assessment determines that the driving risk is high.

3. The method of claim 1 , wherein the medication decision comprises maintaining or reducing the amount of medication infused if the driving risk assessment determines that the driving risk is low.

4. The method according to claim 1 , wherein the component information of the waste plastic decomposition oil includes at least one of chemical properties and physical properties of the waste plastic decomposition oil.

5. 5. The method of claim 4, wherein the chemical property comprises at least one selected from the group consisting of bromine number, total acid number, total chlorine, and corrosivity.

6. 5. The method of claim 4, wherein the physical property comprises at least one selected from the group consisting of pour point, viscosity, and specific gravity.

7. 2. The method of claim 1, wherein the operational risk assessment is performed for each of two or more pieces of equipment in an ethylene plant.

8. 10. The method of claim 1, wherein the agent is selected from the group consisting of corrosion inhibitors, anti-fouling agents, and emulsion breakers.

9. 1. A method for controlling injection of a chemical in an ethylene plant, comprising the steps of: Conduct an operational risk assessment based on the composition information of waste plastic cracking oil in naphtha cracker feedstock and the proportion of waste plastic cracking oil; determining at least one of the type and amount of chemical to be injected into the plant based on the risk assessment of the operation; and The method includes injecting an agent into the plant based on the determination when using the waste plastic cracking oil after performing the risk assessment of the operation.

10. 1. An apparatus for controlling the injection of chemicals in an ethylene plant, comprising: A data acquisition unit for acquiring component information of waste plastic cracking oil contained in a naphtha cracker feedstock; An evaluation unit that performs an operation risk evaluation based on component information of the waste plastic decomposition oil and the ratio of the waste plastic decomposition oil in the raw material; A determination unit that determines at least one of the type and amount of a chemical to be injected into the plant based on the risk assessment of the operation; and A controller that controls injection of the medication based on a decision of the decision unit.

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