Recovery of light olefins from pyrolysis of waste plastics

Abstract

The present application provides systems and methods for integrating a reactor for pyrolysis of polyolefins with a steam cracker effluent treatment train. Polyolefins may correspond to, for example, polyolefins in plastic waste. Integration of the polyolefin pyrolysis process with the steam cracker treatment train can convert polymer mixtures into monomer units while reducing or minimizing cost and / or equipment footprint. This can allow polyolefins to be directly converted into light olefin monomers with high yields while significantly reducing capital and energy use due to integration with the steam cracking process train. Integration can be achieved in part by selecting a feed with a suitable mixture of various polymer types and / or by limiting the volume of plastic waste pyrolysis products relative to the volume of a steam cracker from a steam cracking process train. By selecting plastic waste and / or other polyolefin sources with a suitable polyolefin mixture as raw materials, the resulting polyolefin pyrolysis products can be separated in the steam cracking process train to produce a separate fraction for various polymer-grade small olefin products.

Description

[0001] Inventors: Sundararaian Uppili, Bryan A. Patel, Randolph J. Smiley, Lawrence R. Gros, Anthony Go, Saurabh S. Maduskar, Melissa D. Foster and Philippe Laurent

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to USSN 62 / 861,166, filed June 13, 2019, the disclosure of which is incorporated herein by reference. Technical Field

[0004] The present application provides a system and method for recovering light olefins produced by pyrolysis of plastic waste. Background Art

[0005] The recycling of plastic waste is an increasingly important topic. Typically, polyolefins in plastic waste are converted to produce energy through various methods such as pyrolysis or gasification. While this provides a second way to use waste plastics, ultimately the process of generating energy from plastic waste also results in the conversion of plastic waste into CO 2 In order to make the process completely closed-loop so that the polymer can be recycled back to the same use, these pyrolysis and gasification products need to undergo further pyrolysis or conversion processes to return them to light olefin monomers. The olefin monomers can then be repolymerized back into polyolefins for the same use. Unfortunately, this method of making light olefins is high in energy usage, capital required, and produces relatively low yields of light olefin monomers.

[0006] It is desirable to develop systems and methods that can allow closed loop recycling pathways for polyolefins with improved olefin yields and / or reduced energy usage. In particular, it is desirable to develop systems and methods that can allow individual monomers to be recovered separately from plastic waste corresponding to a polymer mixture.

[0007] U.S. Pat. No. 5,326,919 discloses a method for recovering monomers from polymeric materials. The polymer is pyrolyzed by heating the polymer at a rate of 500°C / sec in a flow-through reactor in the presence of a heat transfer material such as sand. A cyclone separator is used to separate the fluid products produced during pyrolysis from the solids. However, the resulting gas phase monomer product corresponds to a mixture of olefins and is therefore unsuitable for synthesizing new polymers.

[0008] US Patent No. 9,212,318 discloses a catalyst system for pyrolyzing plastics to form olefins and aromatic substances. The catalyst system includes a combination of an FCC catalyst and a ZSM-5 catalyst. Summary of the invention

[0009] In various aspects, a method for pyrolyzing a mixed polyolefin feed is provided. The method includes exposing a feedstock containing a polyolefin mixture to polyolefin pyrolysis conditions to form a pyrolysis effluent. The mixture of polyolefins may include two or more types of monomers. The polyolefin pyrolysis conditions may include heating the feedstock at a rate of 100°C / second or more to form a heated reaction mixture having a temperature of 500°C to 900°C. The polyolefin pyrolysis conditions may further include cooling the heated reaction mixture to a temperature of less than 500°C to form a pyrolysis effluent, such that the heated reaction mixture is at a temperature of 500°C or more for 0.1 seconds to 5.0 seconds. After pyrolysis, the pyrolysis effluent may be initially separated to form at least a pyrolysis product fraction and a fraction containing solid particles. In addition to the pyrolysis of the polyolefin feedstock, a separate steam cracker feed may be passed into a steam cracking reactor to form a steam cracker reactor effluent. At least a portion of the steam cracker reactor effluent can be passed into a primary fractionator to form at least a first fractionator product and one or more other fractionator products having a higher boiling range than the first fractionator product. At least a portion of the first fractionator product and at least a portion of the pyrolysis product fraction can be passed into a process gas compressor to form a compressed olefin product fraction. The volume of the pyrolysis product fraction can correspond to 0.1 vol% to 20 vol% of the combined volume of at least a portion of the first fractionator product and the pyrolysis product fraction. The method can further include separating at least a first product stream comprising ethylene and a second product stream comprising propylene from the compressed olefin product fraction.

[0010] In various aspects, an integrated system for performing polyolefin pyrolysis and steam cracking is provided. The system may include a polyolefin processing section for forming a polyolefin feedstock. The system may also include a pyrolysis reactor, the pyrolysis reactor including a pyrolysis inlet and a pyrolysis outlet. The pyrolysis inlet may be in fluid communication with the polyolefin processing section. The system may also include a first separation section, the first separation section including a first separation section inlet, a first vapor outlet, and a first solid outlet. The first separation section inlet may be in fluid communication with the pyrolysis outlet. The system may also include a pyrolysis quenching section in fluid communication with the first vapor outlet. The system may also include a second separation section, the second separation section including a second separation section inlet, a second light material outlet, and a second heavy material outlet. The second separation section inlet may be in fluid communication with the pyrolysis quenching section. The system may also include a steam cracking reactor, the steam cracking reactor including a reactor outlet. The system may also include a primary fractionator, the primary fractionator including one or more fractionator inlets and a plurality of fractionator outlets. One or more fractionator inlets may be in fluid communication with the reactor outlet and the second heavy material outlet. The system may further include at least one quench tower, the quench tower includes one or more quench tower inlets and one or more quench tower outlets. At least one quench tower inlet can be in fluid communication with at least one fractionator outlet and a second heavy material outlet. The system may also include a process gas compressor, the process gas compressor includes a compressor inlet and a compressor outlet. The compressor inlet can be in fluid communication with one or more quench tower outlets. In addition, the system may include a plurality of olefin separation sections, the olefin separation section at least includes an ethylene outlet and a propylene outlet. A plurality of olefin separation sections can be in fluid communication with the compressor outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Examples of parts of process trains for pyrolysis of various feedstocks are shown.

[0012] Figure 2 Another part of the process train for pyrolyzing various feedstocks is shown.

[0013] Figure 3 An overview of examples of integrated process trains for pyrolysis of various feedstocks is shown.

[0014] Figure 4 An overview of another example of an integrated process train for pyrolysis of various feedstocks is shown. DETAILED DESCRIPTION OF THE INVENTION

[0016] All numerical values ​​in this detailed description and claims are modified by the indicated value of "about" or "approximately", and take into account experimental error and variations that would be expected by a person of ordinary skill in the art.

[0017] In various aspects, systems and methods for integrating a reactor for pyrolysis of polyolefins with a steam cracker effluent treatment train are provided. Polyolefins may correspond to, for example, polyolefins in plastic waste. Integration of the polyolefin pyrolysis process with the steam cracker treatment train may convert polymer mixtures into monomer units while reducing or minimizing cost and / or equipment footprint. This may allow polyolefins to be directly converted into light olefin monomers with high yields while significantly reducing capital and energy use due to integration with the steam cracking process train. Integration may be achieved in part by selecting a feed with a suitable mixture of various polymer types and / or by limiting the volume of the plastic waste pyrolysis product relative to the volume of the steam cracker from the steam cracking process train. By selecting plastic waste and / or other polyolefin sources with a suitable polyolefin mixture as raw materials, the resulting polyolefin pyrolysis product may be separated in the steam cracking process train to produce a separate fraction for various polymer grade small olefin products.

[0018] In addition to selecting an appropriate feed envelope, integration of polyolefin pyrolysis with a steam cracker process train can also be achieved by including one or more contaminant removal sections. The contaminant removal section can be located before and / or within the steam cracking process train. The contaminant removal section can include, but is not limited to, guard beds and wash sections to capture contaminants, such as acidic and / or alkaline wash sections. For example, a guard bed can be included or added to a steam cracking process train to handle silicon that may be present in some polymer formulations.

[0019] Polyolefin polymers are commonly used in a variety of industrial and consumer applications. In some cases, large amounts of polymer / plastic waste corresponding to a single type of polyolefin are available, but more typically polyolefin waste corresponds to a mixture of polyethylene, polypropylene and / or other polymer chains based on small olefins.

[0020] Polyolefins can be pyrolyzed under pyrolysis conditions to form a gas phase pyrolysis product including olefin monomers. Although the pyrolysis conditions can change the selectivity of olefin monomers, the pyrolysis reaction produces a mixture of olefin monomers. This can correspond to a mixture comprising C 2 -C 4 A mixture of olefins, including C 2 -C 3 A mixture of olefins, or containing C 2 Olefins, C 3 Olefins, optionally C 4 olefins, and one or more additional olefins (such as C 5 or C 6Olefins) are a mixture of olefins (olefins). Due to the cost and complexity of separating various types of olefin monomers, plastic waste pyrolysis is usually used instead to form liquid fuels and / or generate heat to generate electricity. However, it is desirable to be able to form polymer-grade olefin fractions by plastic waste / polyolefin pyrolysis, because the ethylene and / or propylene monomer yields from polyolefin pyrolysis can be higher than the ethylene and / or propylene yields from the steam cracking of crude oil fractions. For example, the yield of ethylene plus propylene monomers from the pyrolysis of mixed polyolefin polymers can be 45wt% or higher, or 50wt% or higher, such as up to 65wt%, relative to the weight of polyolefins in the feed. This is roughly equivalent to the olefin yield of naphtha steam cracking. This is unexpected, because the olefin yield from steam cracking is usually inversely proportional to the boiling range and / or molecular weight of the feed for steam cracking, until the point where the feed contains too many components with boiling points higher than the vacuum gas oil range and / or contains too many components with low hydrogen-to-carbon ratios. For example, steam cracking of a typical crude oil fraction generally produces an ethylene plus propylene yield of about 30 wt% to 40 wt% relative to the weight of the feed. Without being bound by any particular theory, the increased yield of ethylene and / or propylene monomers from the pyrolysis of polyolefin polymers relative to the pyrolysis of liquid crude oil fractions can be attributed in part to the increased amount of paraffinic compounds in the feed comprising the polyolefin polymer.

[0021] In the integrated method, at least a portion of the ethylene and / or propylene produced by the steam cracking process train can correspond to the ethylene and / or propylene produced by the pyrolysis of polyolefin (for example, polyolefin from plastic waste). The amount of ethylene and / or propylene derived from the pyrolysis of polyolefin can be measured in any convenient manner, for example, by mass balance. For example, a first processing operation can be carried out, in which the unique effluent entering the steam cracking process train is the effluent from the corresponding steam cracking reactor. Then a second processing operation can be carried out, in which the effluent from the steam cracking reactor keeps constant while the other effluent from the pyrolysis reactor is added to the steam cracking process train in a suitable position. The difference in the ethylene and / or propylene yield obtained can correspond to the additional yield from the polyolefin pyrolysis process.

[0022] Steam cracking is a type of pyrolysis process that can be used to convert various types of petroleum feeds and / or crude oil fractions to form olefin products. Traditionally, steam cracking is not considered a suitable method for processing polymer / plastic waste. The steam cracker includes a convection section and a radiant section. During steam cracking, the feed is preheated in the convection section. Most of the cracking occurs in the radiant section, where the temperature is 800°C or higher, but the residence time is only a few milliseconds. In order to reduce or minimize the fouling caused by coke formation in the cracking section, the steam cracker feed is evaporated before entering the radiant section. In addition, in order to promote the evaporation of the feed before entering the radiant section, the heavy feed of the steam cracker is separated before being exposed to pyrolysis conditions to remove the bottom product fraction. Therefore, the steam cracker feed generally has a T95 boiling point of 450°C or lower. In contrast, based on the polymer chain length, mixed polyolefin waste can correspond to polymers with boiling points far above 500°C. Even if such polyolefins are not removed by separation, they can lead to rapid fouling of the steam cracker since the polyolefins cannot be vaporized under the conditions in the convection or radiant zones.

[0023] In some aspects, it is possible to substantially consist of a lightweight (C 2 -C 4 ) hydrocarbon feedstock is subjected to steam cracking, such as ethane steam cracking. This steam cracking of light hydrocarbons can produce about 70% ethylene and / or propylene yields. However, it is not always feasible to provide sufficient amounts of light hydrocarbon feedstock to provide olefins for industrial-scale polymer production. Therefore, steam cracking is also used to process crude oil fractions and / or other liquid feedstocks.

[0024] In those aspects where the feed for steam cracking corresponds to a liquid feed, fractionation of the steam cracker product is typically performed to separate higher and lower value portions of the steam cracker product. For example, in addition to light olefins, products from steam cracking of a liquid feed (such as a crude oil fraction) may include steam cracker naphtha, steam cracker gas oil, and steam cracker tar. For light olefins, an additional separation stage may be used to separate the C olefins within the light olefin product. 2 , C 3 and C 4 Olefins. In this discussion, a liquid feed for steam cracking refers to a feed that is at least partially liquid at 20°C and 100 kPa-a.

[0025] It has been discovered that the product recovery and separation section of a steam cracker process train can be used to process limited amounts of pyrolysis effluent from a plastic waste / polyolefin pyrolysis process. By integrating the plastic waste / polyolefin pyrolysis process with the steam cracking process, the amount of additional separation equipment required for the pyrolysis process can be reduced or minimized while still allowing the light olefin monomers to be separated into ethylene, propylene and / or other monomers present in the plastic waste mixture.

[0026] In this specification, the reference to "C x "A fraction, stream, portion, feed or other quantity is defined as the fraction (or other quantity) in which 50 wt% or more of the fraction corresponds to hydrocarbons having "x" carbon numbers. When a range is specified, e.g., "C x -C y ", 50 wt% or more of the fraction corresponds to hydrocarbons having a carbon number between "x" and "y". x+ "(or "C x- ") corresponds to a fraction in which 50 wt% or more of the fraction corresponds to hydrocarbons having a specified carbon number or more (or a specified carbon number or less).

[0027] Polyolefin raw materials

[0028] In various fields, when plastic waste / polyolefin pyrolysis process is integrated with steam cracking treatment train, the raw material for pyrolysis may include one or more polyolefin polymers or be basically composed of one or more polyolefin polymers.System and method described in the present application may be applicable to the plastic waste corresponding to single type olefin polymer. However, other benefits can be realized when plastic raw material contains polymers including multiple monomer types. In the aspect that raw material is basically composed of polyolefin polymer, raw material may include polyolefin polymer and any additive, modifier, packaging dye and / or other components that are usually added to polymer during preparation and / or afterwards. Raw material may further include any component usually found in polymer waste. Finally, raw material may further include one or more solvents or carriers so that the raw material of pyrolysis process corresponds to solution or slurry of polyolefin polymer.

[0029] The polyolefin raw material can include at least one of polyethylene and polypropylene.Polyethylene can correspond to the polyethylene of any suitable type, such as the polyethylene of high density or low density form.Similarly, the polypropylene of any suitable type can be used.Except polyethylene and / or polypropylene, plastic raw material can optionally include one or more of polystyrene, polyvinyl chloride, polyamide (such as nylon), polyethylene terephthalate and ethylene-vinyl acetate.Still other polyolefin can correspond to the polymer (comprising copolymer) of butadiene, isoprene and isobutylene.In some respects, polyethylene and polypropylene can be present in mixture as the copolymer of ethylene and propylene.More generally, polyolefin can include various olefins, such as the copolymer of ethylene, propylene, butylene, hexene and / or any other olefin that is suitable for polymerization.

[0030] In the present application, unless otherwise stated, the weight of polyolefin polymer in the feedstock corresponds to the weight relative to the total polymer content in the feedstock. Any additives / modifiers / other components included in the formulated polymer are included in this weight. However, the weight percentages stated in the present application do not include any solvents or carriers used, so that the feedstock corresponds to a solution or slurry of the polymer. For compatibility with the introduction of plastic pyrolysis products in the steam cracking process train, the feedstock may include limited amounts of polymers other than polyethylene and / or polypropylene. In various aspects, the plastic feedstock for pyrolysis may include 55 wt% to 100 wt% of polyethylene, polypropylene, copolymers of ethylene and propylene, other C 4 -C 6 Olefins and / or dienes or combinations thereof. In aspects where the feedstock corresponds to 95 wt% or more of a polymer derived from ethylene and propylene, the feedstock may preferably include 10 wt% or more of ethylene monomer and 10 wt% or more of propylene monomer.

[0031] In the aspect that plastic raw material comprises polyethylene and / or polypropylene less than 100wt%, plastic raw material can optionally comprise 0.1wt% or more other polymer.For example, in some aspects plastic raw material can comprise polystyrene of 0.1wt% to 35wt%, or 1.0wt% to 35wt%, or 0.1wt% to 20wt%, or 1.0wt% to 20wt%, or 10wt% to 35wt%, or 5wt% to 20wt%.Including polystyrene in the feed can increase the yield of aromatic substances, including the yield of styrene.In some aspects, styrene can be separated and used to produce polystyrene.In addition or alternatively, styrene can be blended with steam cracking naphtha produced by steam cracking process.It should be noted that along with the amount of polystyrene increases, the yield of ethylene and / or propylene monomer may reduce.Limiting the amount of polystyrene can allow the polyethylene / polypropylene in plastic raw material to produce ethylene and / or propylene in an amount greater than conventional steam cracker yield. Additionally, polystyrene can potentially be recycled by processing at lower temperatures, such as about 450° C., to convert the polystyrene to styrene monomer. Thus, limiting the polystyrene content in the polyolefin feed may also be beneficial in order to allow the polystyrene to be processed under more favorable conditions.

[0032] In some aspects, the plastic feedstock may optionally include 0.1 wt% to 10 wt%, or 0.1 wt% to 2.0 wt%, or 0.1 wt% to 1.0 wt% of polyvinyl chloride, polyvinylidene chloride, or a combination thereof; and / or 0.1 wt% to 1.0 wt% of polyamide. Polyvinyl chloride contains approximately 65 wt% chlorine. Therefore, pyrolysis of polyvinyl chloride (and / or polyvinylidene chloride) may result in the formation of a large amount of hydrochloric acid relative to the initial weight of polyvinyl chloride. Before allowing the pyrolysis products to enter the steam cracking process train, a guard bed may be used to remove a limited amount of hydrochloric acid produced by the pyrolysis of polyvinyl chloride and / or polyvinylidene chloride. With respect to polyamide, pyrolysis results in NO x The formation of limited NO x It can be processed by a steam cracking process train. In other aspects, 0.1 wt% to 10 wt% polyvinyl chloride and / or polyvinylidene chloride can be optionally included in the feed by including an additional chlorine removal stage before combining the polyolefin pyrolysis product with the steam cracking process train.

[0033] In some aspects, the plastic raw material may optionally include 0.1 wt% to 10 wt% or 1.0 wt% to 10 wt% of polyethylene terephthalate. Additionally or alternatively, the plastic raw material may optionally include 0.1 wt% to 10 wt% or 1.0 wt% to 10 wt% of ethylene vinyl acetate. Both polyethylene terephthalate and ethylene vinyl acetate may reduce the yield of ethylene and / or propylene monomers, while also potentially increasing CO, CO 2 Limiting the amount of polyethylene terephthalate and / or ethylene vinyl acetate can allow the production of ethylene and / or propylene from the polyethylene / polypropylene in the plastic feedstock in amounts greater than conventional steam cracker yields.

[0034] In various aspects, the polyolefin can be prepared for incorporation into a plastic feedstock. A process for preparing the polyolefin can include reducing the particle size of the polyolefin and mixing the polyolefin with a solvent or carrier.

[0035] In the aspect that polymer waste material / polyolefin is introduced into pyrolysis reactor at least in part as solid, having little particle size can promote solid to be transported in pyrolysis reactor.Less particle size can also contribute potentially to realize the desired conversion level of polymer / polyolefin under pyrolytic short residence time condition.In order to prepare the solid that is used for pyrolysis, solid polymer / polyolefin can be crushed, shredded, ground or otherwise physically treated so that median particle size is reduced to 3.0cm or littler, or 2.5cm or littler, or 2.0cm or littler, or 1.0cm or littler, for example, as low as 0.01cm or may be littler.In order to determine the median particle size, particle size is defined as the diameter of the minimum boundary sphere that contains particle.

[0036] Additionally or alternatively, a solvent or carrier can be added to the raw material. In order to introduce into the pyrolysis reactor, polymer waste / polyolefin can be suitably in the form of a solution, slurry or other fluid phase. If a solvent is used to at least partially solvate polyolefin, any convenient solvent can be used. The example of a suitable solvent may include, but is not limited to, a wide range of petroleum or petrochemical products. For example, some suitable solvents include crude oil, naphtha, kerosene, diesel and gas oil. Other potential solvents may correspond to cycloalkane and / or aromatic solvents, such as toluene, benzene, methylnaphthalene, cyclohexane, methylcyclohexane and mineral oil. Still other solvents may correspond to refinery fractions, such as gas oil fractions or naphtha fractions from steam cracker products. If a carrier is used, the carrier may correspond to a liquid or gas phase carrier, such as steam.

[0037] Processing Conditions - Polyolefin Pyrolysis

[0038] In various aspects, first by cutting polyolefin into small particles and / or by dissolving polyolefin in solvent to prepare polyolefin waste.Then the prepared raw material can be transported to a suitable reactor, such as a fluidized bed thermal cracker.Then the raw material is heated to a temperature between 500 ℃-900 ℃ for a reaction time to carry out pyrolysis.The temperature may depend in part on the desired product.Higher temperatures can increase the selectivity to ethylene, while lower temperatures can increase the selectivity to propylene.The reaction time in which the raw material is maintained at or above 500 ℃ can be limited to reduce or minimize the formation of coke.In some aspects, the reaction time may correspond to 0.1 second to 6.0 seconds, or 0.1 second to 5.0 seconds, or 0.1 second to 1.0 seconds, or 1.0 seconds to 6.0 seconds, or 1.0 seconds to 5.0 seconds.At the end of the reaction time, the pyrolyzed raw material is cooled to less than 500 ℃.

[0039] In some aspects, diluent steam can also be fed into the pyrolysis reactor to control the olefin partial pressure and increase the ethylene and propylene yields. The steam is also used as a fluidizing gas. The weight ratio of the steam to the feedstock can be between 0.3:1 and 10:1.

[0040] The heating and cooling of the raw material / pyrolysis product can be carried out in any convenient way that allows the raw material to be heated quickly. In some aspects, at least a portion of the raw material being heated to the pyrolysis temperature can be carried out at a heating rate of 100°C / second or higher, or 200°C / second or higher, such as up to 1000°C / second or possibly faster. As an example, in the aspect that the pyrolysis reactor corresponds to a fluidized bed, the heating of the raw material can be carried out by mixing the raw material with heated fluidized particles. Sand is an example of a suitable type of particle for a fluidized bed. During operation, sand (or another type of heat transfer particle) can enter the regenerator to burn off the coke and heat the particles. Additional heat must be supplied in the regenerator to compensate for the low coke formation in the process. The heated particles can then be mixed with the raw material before entering the reactor. By heating the heat transfer particles to a temperature higher than the desired pyrolysis temperature, the heat transfer particles can provide at least a portion of the heat required to achieve the pyrolysis temperature. For example, the heat transfer particles can be heated to a temperature 100°C or more higher than the desired pyrolysis temperature. Optionally, if the feedstock, sand, and fluidizing steam do not provide sufficient material to form a fluidized bed, additional fluidizing gas, such as additional nitrogen, may be added, but this will also result in a corresponding increase in the volume of the gas stream that needs to be handled during product recovery. After leaving the pyrolysis reactor, a cyclone separator or another solid / vapor separator may be used to separate the heat transfer particles from the vapor portion of the pyrolysis effluent. Such a separator may also remove any other solids present after pyrolysis. It should be noted that separation using a cyclone separator may result in N in the steam cracker effluent. 2 Optionally, in addition to the cyclone separator or other primary solid / vapor separator, one or more filters may be included at a location downstream from the cyclone separator to allow for removal of fine particles entrained in the gas phase.

[0041] One of the difficulties of polyolefin pyrolysis may be to handle the chlorine released during the pyrolysis process, such as the chlorine obtained by the pyrolysis of polyvinyl chloride and / or polyvinylidene chloride. In some aspects, the generation of chlorine in the pyrolysis reactor can be alleviated by including a calcium source (such as calcium oxide particles) in the heat transfer particles. In the pyrolysis environment, calcium oxide can react with the chlorine produced during the pyrolysis to form calcium chloride. The calcium chloride can then be purged from the system as a part of the purge flow of the heat transfer particles. The corresponding supplementary flow of fresh heat transfer particles can be introduced to keep the required amount of heat transfer particles in the polyolefin pyrolysis section.

[0042] After the solids are removed, the product may be cooled to a temperature of 300°C to 400°C using a heat exchanger (or another suitable method) to stop the reaction and recover heat. Further quenching may then be performed, such as quenching using a liquid stream from a primary fractionator of a steam cracker. An example of a quench stream may be a highly aromatic liquid such as a gas oil fraction produced by pyrolysis or steam cracking (e.g., steam cracked gas oil). A combination of quenching and / or other cooling may be sufficient to reduce the C content of the product to 1.5 %. 5+ Partially become liquid to facilitate separation.

[0043] The cooled stream can then be sent to a liquid-gas separator to separate the C 5+ The remaining C of the liquid and any quench oil and pyrolysis products 4- Partial separation. 4- The fraction may also include any gas phase oxides produced during the pyrolysis process (e.g. CO x 、NO x 、SO x ). The liquid stream may be sent to the primary fractionator of the steam cracker. 4- The gas stream is sent to a secondary quench tower. In the quench tower, C is washed with water. 4- The washed and dried C 4- The remainder of the gas stream is passed through one or more guard beds to remove contaminants, and the washed and dried C 4- The remainder of the gas stream is sent to the inlet of the process gas compressor of the steam cracker process train. 4- The remainder of the gas stream is combined with the gas product from the steam cracker. Using a second quench tower on the polyolefin pyrolysis gas phase product can reduce or minimize the amount of flow through the guard bed to remove chlorine. Alternatively, if C 4- The gas stream is substantially free of contaminants such as chlorine (i.e., contaminants not normally present in steam cracker products), then C 4- The gas stream is fed to a quench tower as part of a steam cracker process train, and / or the C 4- The gas stream is introduced at another location, such as in a primary fractionator or a process gas compressor.

[0044] In all aspects, C 4- The volume of the gas stream may correspond to a smaller portion of the total flow entering the process gas compressor and / or the olefin separation section. 4-The volume of the gas stream may correspond to 0.1 vol% to 20 vol%, or 0.1 vol% to 10 vol%, or 1.0 vol% to 20 vol%, or 5.0 vol% to 20 vol%, or 1.0 vol% to 10 vol% of the gas stream in the process gas compressor relative to C. 4- The combined volume of the gas stream and the gas stream provided to the process gas compressor from the steam cracker product.

[0045] The mixed gas products from polymer pyrolysis and steam cracking are separated by processing through a series of refrigeration, compression and distillation steps. In some aspects, this can allow the formation of polymer grade ethylene, propylene, isobutylene, butene and butadiene with a purity of at least 99.9%. To achieve this purity, the separation step can include the steps of separating ethane from ethylene, separating propane from propylene, and separating butane and / or butene from butadiene.

[0046] Processing conditions - steam cracking

[0047] Steam cracking is a type of pyrolysis process. In various aspects, the feed for steam cracking can correspond to any type of liquid feed (i.e., a feed that is liquid at 20°C and 100 kPa-a, as defined in the present application). Examples of suitable reactor feeds may include whole and partial crudes, naphtha boiling feeds, distillate boiling range feeds, residual oil boiling range feeds (normal pressure or vacuum) or combinations thereof. Additionally or alternatively, a suitable feed may have a T10 distillation point of 100°C or higher, or 200°C or higher, or 300°C or higher, or 400°C or higher, and / or a suitable feed may have a T95 distillation point of 450°C or lower, or 400°C or lower, or 300°C or lower, or 200°C or lower. It should be noted that the feed for steam cracking may be fractionated before steam cracking to remove the bottom product portion so that the feed entering the reactor has a T95 distillation point of 450°C or lower. The distillation boiling range of the feed can be determined, for example, according to ASTM D2887. If ASTM D2887 is not suitable for some reason, ASTM D7169 can be used instead. Although certain aspects of the present invention are disclosed with reference to specific feeds, such as feeds with a defined T95 distillation point, the present invention is not limited thereto, and the description is not meant to exclude other feeds within the broader scope of the present invention.

[0048] A steam cracking unit typically includes a furnace facility for producing a steam cracking effluent and a recovery facility for removing various products and by-products, such as light olefins and pyrolysis tars, from the steam cracking effluent. The furnace facility typically includes a plurality of steam cracking furnaces. A steam cracking furnace typically includes two main sections: a convection section and a radiant section, the radiant section typically containing a burner. Flue gas from the radiant section is conveyed from the radiant section to the convection section. The flue gas flows through the convection section and may then optionally be treated to remove combustion by-products, such as NO x . Hydrocarbons are introduced into a tubular coil (convection coil) located in the convection section. Steam is also introduced into the coil, where the steam is combined with the hydrocarbons to produce a steam cracking feed. The combination of indirect heating by flue gas and direct heating by steam results in vaporization of at least a portion of the hydrocarbon components in the steam cracking feed. The steam cracking feed containing the vaporized hydrocarbon components is then transferred from the convection coil to a tubular radiant tube located in the radiant section. The indirect heating of the steam cracking feed in the radiant tube results in cracking of at least a portion of the hydrocarbon components in the steam cracking feed. The steam cracking conditions in the radiant section may include, for example, one or more of the following: (i) a temperature in the range of 760° C. to 880° C., (ii) a pressure in the range of 1.0 to 5.0 bar (absolute pressure), or (iii) a cracking residence time in the range of 0.10 to 0.5 seconds.

[0049] The steam cracking effluent is directed from the radiant section and is typically quenched with water or quench oil. The quenched steam cracking effluent is directed from the furnace facility to a recovery facility for separation and recovery of reacted and unreacted components of the steam cracking feed. The recovery facility typically includes at least one separation section, for example, for separation of one or more of light olefins, steam cracker naphtha, steam cracker gas oil, steam cracker tar, water, light saturated hydrocarbons, and molecular hydrogen from the quench effluent.

[0050] Steam cracking feeds typically comprise hydrocarbons and steam, such as 10.0wt% or more hydrocarbons, based on the weight of the steam cracking feed, or 25.0wt% or more, or 50.0wt% or more, or 65wt% or more, and may be up to 80.0wt% or may be still higher. Although hydrocarbons may comprise one or more light hydrocarbons such as methane, ethane, propane, butane, etc., it may be particularly advantageous to comprise a large amount of higher molecular weight hydrocarbons. Using a feed comprising higher molecular weight hydrocarbons can reduce feed costs, but it will also increase the amount of steam cracker tar in the steam cracking effluent. In some aspects, suitable steam cracking feeds may comprise 10wt% or more, or 25.0wt% or more, or 50.0wt% or more (based on the weight of the steam cracking feed) of hydrocarbon compounds in liquid and / or solid phases at ambient temperature and atmospheric pressure, such as until substantially the entire feed corresponds to heavy hydrocarbons.

[0051] The hydrocarbon portion of the steam cracking feed may include 10.0 wt% or more, or 50.0 wt% or more, or 90.0 wt% or more (based on the weight of the hydrocarbons) of one or more of naphtha, gas oil, vacuum gas oil, waxy residue, atmospheric residue, residue mixture or crude oil, for example, up to substantially the entire feed. Such components may include those containing 0.1 wt% or more asphaltenes. When the hydrocarbons include crude oil and / or one or more fractions thereof, the crude oil is optionally desalted prior to inclusion in the steam cracking feed. Crude oil fractions may be produced by separating the atmospheric pressure tube still ("APS") bottoms from the crude oil and then subjecting the APS bottoms to a vacuum tube still ("VPS") treatment. One or more gas-liquid separators may be used upstream of the radiant section, for example, to separate and derive a portion of any non-volatile matter in the crude oil or crude oil components. In certain aspects, such a separation section is integrated with a steam cracker by preheating the crude oil or its fractions (and optionally by adding dilution steam) in a convection section, separating the bottoms product vapor containing non-volatiles, and then directing the primarily vapor overhead stream as feed to a radiant section.

[0052] Suitable crude oils may include virgin crude oils, such as those rich in polycyclic aromatics. For example, the hydrocarbons of the steam cracking feed may contain 90.0 wt% or more of one or more crude oils and / or one or more crude oil fractions, such as those obtained from atmospheric distillation and / or vacuum distillation; waxy residue; atmospheric residue; naphtha contaminated with crude oil; various residue mixtures; and steam cracker tar.

[0053] Pollutant removal section

[0054] Optionally, the contaminant removal section can be promoted to add the part of effluent from the polyolefin pyrolysis to the steam cracking treatment train. In some respects, one or more contaminant removal sections can be incorporated into the reaction system at the position before the polyolefin pyrolysis effluent is combined with the steam cracking treatment train. In addition or alternatively, one or more contaminant removal sections can be incorporated into the steam cracking process train from the polyolefin pyrolysis effluent and the steam cracking effluent combination. Guard bed (or guard bed group) is the example of the contaminant removal section type. Optionally, water washing under acidic or alkaline conditions is another example of the contaminant removal section type.

[0055] Polyolefin can comprise multiple pollutants, and the amount of this pollutant is greater than the crude oil fraction used as steam cracking feed.This can include pollutants such as chlorine that do not exist substantially in typical crude oil fractions.This can also include pollutants, such as oxygen and nitrogen, which can adopt the amount of increase to be present in the polyolefin feed.Some pollutants can correspond to the components of following polyolefin, such as nitrogen in the chlorine in the polyvinyl chloride or the polyamine.Due to the additive that comprises when the polymer of preparation preparation and / or due to packaging, adhesive and other compounds integrated with polyolefin after preparation, other pollutants may be present.Such additives, packaging, adhesive and / or other compounds can include additional pollutants such as chlorine, mercury and / or silicon.

[0056] One type of contaminant removal can be the use of water scrubbing to remove chlorine before combining the pyrolysis effluent with a steam cracker process train and / or after the process gas compressor. Optionally, the water scrubbing can correspond to an amine scrubbing and / or an alkaline scrubbing. The use of an amine scrubbing and / or an alkaline scrubbing can help remove chlorine and other contaminants such as CO. 2 Another option to perform an amine wash may be to include an amine in the quench oil used for the initial quench of the pyrolysis and / or steam cracker effluent. This may allow for a subsequent water wash to remove chlorine.

[0057] Another form of contaminant removal can be achieved based on pH control in the quench tower. Based on the additive used for pH control, any NH 3 At least a portion of the quench water may be converted to ammonia salts. These salts may then be retained in the quench water and / or removed by a separate water wash.

[0058] Additionally or alternatively, additional guard beds may be included to remove Cl and / or HCl. In aspects where the polyolefin feed contains 2.0 wt% or less of polyvinyl chloride and / or polyvinylidene chloride, a guard bed for removing chlorine compounds may be included after the supplemental quench tower. Examples of suitable guard bed particles for dechlorination include calcium oxide, magnesium oxide, zinc oxide, and combinations thereof. In aspects where there is a higher amount of chlorine in the feed, such as up to 10 wt% of polyvinyl chloride and / or polyvinylidene chloride, additional treatment of the feed may be performed before pyrolysis to remove chlorine. For example, prior to pyrolysis, such a polyolefin feed may be heated to a temperature of 350°C-450°C to convert chlorine into a gas phase compound. The heated feed may then be passed through a guard bed (e.g., a calcium oxide guard bed) and / or through a water wash, alkali scrubber, or amine scrubber to remove most of the chlorine from the feed before entering the pyrolysis reactor.

[0059] Still another type of guard bed may correspond to a guard bed for removing ammonia. In addition to nitrogen-containing polymers such as polyamines, various types of polymer additives may include nitrogen. In a pyrolysis environment, a portion of this nitrogen may be converted into ammonia. Various types of adsorbents may be used to remove ammonia, such as molecular sieve-based adsorbents. Another option may be to have a supplemental quench tower so that ammonia can be removed using water washing before combining the pyrolysis effluent with the steam cracking effluent. Further nitrogen removal may be performed by adding a nitrogen adsorbent (e.g., a molecular sieve suitable for ammonia adsorption) to one or more process gas dryers located downstream of the process gas compressor.

[0060] In addition to the above-mentioned contaminant removal section used before combining the pyrolysis effluent with the steam cracker product material effluent, other contaminant removal sections for treating the combined effluent may be included. For example, silicon is commonly present in additives used in polymer formulations. After pyrolysis, silicon is usually separated into liquid products. A silicon trap can be added to the steam cracking process train to remove silicon from the liquid steam cracker effluent after it leaves the quench tower.

[0061] Fixed bed mercury traps may also be included in steam cracking process trains. The elevated temperatures present in the pyrolysis reaction environment may convert any mercury present in the polyolefin feed into elemental mercury. This elemental mercury may then be removed using a guard bed. It should be noted that some guard beds suitable for mercury removal may also be suitable for silicon removal. Examples of such guard beds include guard beds comprising optionally supported refractory oxides with transition metals on the surface, such as oxides and metals for demetallization catalysts or spent hydroprocessing catalysts. Additionally or alternatively, separate guard beds may be used for silicon and mercury removal, or separate adsorbents for silicon removal and mercury removal may be included in a single guard bed. Examples of suitable mercury adsorbents and silicon adsorbents may include, but are not limited to, molecular sieves suitable for adsorbing mercury and / or silicon.

[0062] Other contaminant removal stages may correspond to contaminant removal that may already exist in the steam cracking process train. For example, any nitrogen oxides may accumulate as salts in the cold box, thereby removing nitrogen oxides from the process gas. The cold box may be periodically washed to remove accumulated salts formed by nitrogen oxides. Amine or alkaline washing may be used to remove CO 2 The CO may be removed by methanation of the CO at a downstream location. Additional ammonia and / or oxygen removal stages may also be included.

[0063] Configuration Example

[0064] Figure 3 An overview of a possible integrated system including both a steam cracking process train and a pyrolysis reactor is shown. Figure 3In the configuration shown, a supplemental quench tower is provided to reduce or minimize the introduction of contaminants not normally present in a steam cracking process train. Figure 3 In the embodiment of the present invention, a feed 305 for steam cracking is introduced into a steam cracking section 320 together with steam 328 to produce a steam cracker effluent 324. The steam cracking section 320 includes a steam cracking furnace, an initial feed separator, and one or more quench coolers for cooling the steam cracker effluent 324. The quench cooler may use a quench oil 362 as a quenching medium. Figure 3 Quench oil 362 is shown returning to the quench cooler in steam cracking section 320. Optionally but preferably, quench oil 362 may also be returned to the quench cooler (not shown) in polyolefin processing section 340. Steam cracker effluent 324 may enter a primary fractionator and quench column section 360.

[0065] Figure 3 It is also shown that the mixed polyolefin feed 301 is sent to the polyolefin processing section 340. In addition to the pyrolysis reactor, the polyolefin processing section 340 may include any pretreatment required for the polyolefin feed, such as dissolving the feed in a solvent or chopping the feed to form particles of a desired size. The polyolefin processing section 340 may also include a gas-solid separation section (e.g., a cyclone separator) for separating sand and / or catalyst fines from the vapor product, a regenerator, and a quenching section for cooling the resulting pyrolysis effluent. The resulting pyrolysis effluent 344 can be sent to a vapor-liquid separator 350. The liquid portion 354 can enter a primary fractionator and a quenching tower section 360. Optionally, at least a portion of the liquid portion 354 can be returned (not shown) to the steam cracking section 320 instead to further increase the C 2 and / or C 3 The productivity of olefins. Steam section 358 can enter pollutant removal section 330. Pollutant removal section 330 can include, for example, water washing for dechlorination and a supplementary quenching tower for cooling steam section 358. In addition or alternatively, chlorine removal (for example, HCl removal) can be realized based on the pH of the water used in the control quenching tower. Steam 332 also can be produced by heat exchange and used as the input of polyolefin treatment section 340. Then the quenched effluent 334 of gained can be combined with the vapor fraction from primary fractionator and quenching tower 360, and then passed into process gas compressor 380. Then the compressed vapor product 384 can be sent to product recovery section 390 to further process and / or separate various required olefin monomers.

[0066] exist Figure 3In the illustrated embodiment, the primary fractionator and quench tower 360 may also produce a tar or bottoms fraction 369, a gas oil fraction 362 and a naphtha boiling range fraction 364 that may be recycled as quench oil. The naphtha boiling range fraction may optionally be passed through a pollutant removal section 366 to form a pollutant-reduced fraction 368. The pollutant removal section 366 may include, for example, a silicon trap. The pollutant-reduced fraction 368 may then be subjected to further processing and / or separation 370 to reclaim desired products, such as naphtha products and / or benzene products.

[0067] Figure 4 Another overview example of a configuration for integrating polyolefin pyrolysis with steam cracking is shown. Figure 4 In the embodiment of the present invention, no supplemental quench tower is included, and instead the contaminant removal section 430 is used to process the pyrolysis effluent 344. This can allow the modified pyrolysis effluent 434 to enter the primary fractionator and quench tower section 460 with the steam cracking effluent 324 for separation and quenching. The quench oil 462 and steam 424 produced by the primary fractionator and quench tower section 460 can be recycled to both the steam cracking section 320 and the polyolefin processing section 340.

[0068] Figure 1 and 2 Additional details of the configuration for integrating polyolefin pyrolysis with a steam cracking process train are shown. Figure 1 In the embodiment, the feed 105 for steam cracking enters the steam cracking reactor 110. Figure 1 In the example shown, any optional removal of high molecular weight fractions from feed 105 has been performed. Optionally, feed 105 can be combined with steam 102 before entering steam cracking reactor 110. Steam cracking reactor 110 can be operated to produce lower molecular weight hydrocarbons, such as C 2 -C 4 Olefins. Under such steam cracking conditions, the steam cracking reactor may also produce various fractions, such as steam cracked naphtha, steam cracker gas oil and steam cracker tar.

[0069] The steam cracker effluent 115 from the steam cracking reactor 110 may then be passed to, for example, a quench section 120 where the steam cracker effluent 115 is indirectly cooled and / or mixed with water or a quench oil (e.g., optional quench oil 157) to cool the effluent. The quench oil may correspond to, for example, a fraction from the primary fractionator 140, such as a steam cracker gas oil fraction or a bottoms fraction, depending on the configuration. The quench effluent 125 may then be passed to the primary fractionator 140. Optionally, the quench effluent may be passed through a tar knockout drum or other separator (not shown) to remove steam cracker tar before entering the primary fractionator 140.

[0070] exist Figure 1 In the illustrated embodiment, the primary fractionator 140 can produce a bottom product 159 (e.g., steam cracker tar), one or more intermediate products 155 (e.g., quench oil and / or steam cracker gas oil), and an overhead product 151 including gas phase components (including olefin monomers) and steam cracker naphtha. A portion of the intermediate product 155 can be used as a quench oil. The overhead product 151 can be further processed, such as Figure 2 shown.

[0071] The second raw material 101 may correspond to a raw material including polyolefins, such as a raw material including plastic waste. The raw material 101 may enter the preparation section 150. In the preparation section 150, the raw material may be physically treated to reduce the particle size of the polyolefin, mixed with a solvent or carrier, or otherwise processed to produce a preparation stream 155 that can be introduced into the pyrolysis reactor 160. Optionally, the preparation stream 155 may be combined with steam 152 before entering the pyrolysis reactor 160. In some aspects, steam 152 may correspond to steam generated by heat exchange at other locations within the reactor train by condensed water. Optionally, the preparation stream 155 may be combined with a circulating stream (not shown) of the heating of heat transfer particles returned to the reactor 160 from a regenerator (not shown). After the pyrolysis of the polyolefin raw material, the pyrolysis effluent 165 may enter the separation section 170 to separate the solid 172 from the remaining product 175. Such a separator may correspond to, for example, a cyclone separator. Separation section 170 may also include one or more optional filters for removing fine particles remaining in the vapor after the cyclone or other primary separator. Optionally, such filters may be located downstream of one or more other sections instead of and / or in addition to having one or more filters in separation section 170. The remaining product 175 may then be quenched or cooled 180, optionally using quench oil 158 from fractionator 140. Cooling 180 may be sufficient to allow for gas-liquid separation 190 of the cooled remaining product 185. Gas-liquid separation 190 may, for example, separate the C 5+ Stream 192 and C 4- The product stream 195 is separated from the cooled remaining product 185. 5+ The stream may enter fractionator 140. C 4- Product stream 195 is fed to a steam cracker process train, for example by feeding stream 195 to Figure 2 The quench tower 211 in the embodiment of the present invention can be used to cool the 4- The product stream 195 is quenched in a secondary quench tower 130 before being fed to the steam cracker process train. In the secondary quench tower 130, the remaining C 4- Steam 133 is removed from product 135.

[0072] Figure 1The connectivity in the embodiment indicates fluid communication between various elements. Fluid communication may include direct fluid communication and indirect fluid communication. Figure 1 In FIG. 1 , the pyrolysis reactor 110 is shown in direct fluid communication with the quench section 120. The pyrolysis reactor 110 is shown in indirect fluid communication with the primary fractionator 140 via the quench section 120.

[0073] Figure 2 A portion of a steam cracking process train that processes the separation of olefin monomers is shown. Figure 1 Fraction 151 and C 4- Fraction 135 is fed to quench column 211. This removes water 219 while forming naphtha fraction 218 and C 4- Fraction 215. C 4- Fraction 135 can be mixed with C 4- The naphtha fraction 218 can then be sent to a hydrotreater 291 and / or another type of silicon removal stage to form a naphtha product 295. 4- Fraction 215 may be compressed in process gas compressor 221. In optional aspects where separate quench columns are used, overhead fractions from separate quench columns may be combined prior to and / or within a stage of process gas compressor 221.

[0074] exist Figure 2 In the illustrated embodiment, after compression, compressed stream 225 may be passed through a wash stage 271, such as a water wash, an alkaline wash, or an amine wash, to remove CO. 2 , HCl and / or NH 3 The scrubber stage effluent 275 may then be passed to a process gas dryer 231. The process gas dryer 231 may optionally but preferably include a contaminant removal stage. For example, the process gas dryer 231 may include a molecular sieve or another type of structure that may function as a mercury trap. Additionally or alternatively, the process gas dryer 231 may include one or more ammonia removal beds.

[0075] The effluent 235 from the process gas dryer / contaminant removal 231 may then be separated to form fractions containing the component monomers. Figure 2 In the example shown, the process may begin by passing effluent 235 to a depropanizer 241. The depropanizer 241 may form C 3+ Products 249 and C 2- Product 245.C 3+ Product 249 can undergo further separation to allow recovery of C 3 Olefins and C 4 Product. C 2-Product 245 may optionally enter acetylene conversion section 281. After optional acetylene conversion, acetylene conversion product 283 may enter demethanizer section 285 to convert CO to CH 4 The demethanizer section 285 may also include a section for removing CH 4 , CO, NO x and H 2 The separator of the material stream 289 can then be 2 The remaining stream 287 of the components is fed to the cold box 252. The cold box 252 can promote the 2 Olefin 265 and C 2 The nitrogen oxide compounds are additionally removed prior to the separation 261 of the paraffins 269. During maintenance situations, any nitrogen oxide compounds that have accumulated in the cold box 252 can be washed out of the system. It should be noted that the cold box 252 is Figure 2 2 is shown between demethanizer section 285 and separation section 261. In various aspects, cold box 252 can correspond to multiple sections (not shown) used for quenching of product distillation at various locations in the distillation process flowsheet.

[0076] Additional Implementation

[0077] Embodiment 1. A method for pyrolyzing a mixed polyolefin feed, comprising: exposing a feedstock comprising a polyolefin mixture to polyolefin pyrolysis conditions to form a pyrolysis effluent, the polyolefin mixture comprising two or more types of monomers, the polyolefin pyrolysis conditions comprising: heating the feedstock at a rate of 100°C / second or more to form a heated reaction mixture having a temperature of 500°C to 900°C, and cooling the heated reaction mixture to a temperature of less than 500°C to form the pyrolysis effluent, the heated reaction mixture being at a temperature of 500°C or more for 0.1 second to 5.0 seconds; initially separating the pyrolysis effluent to form at least a pyrolysis product fraction and a fraction comprising solid particles; steam cracking a steam cracker feed to form a steam cracker reactor effluent; and separating at least one of the steam cracker reactor effluents from the steam cracker reactor effluent. A portion of the olefin product fraction is introduced into a primary fractionator to form at least a first fractionator product and one or more additional fractionator products having a higher boiling range than the first fractionator product; at least a portion of the first fractionator product and at least a portion of the pyrolysis product fraction are introduced into a process gas compressor to form a compressed olefin product fraction, the volume of the pyrolysis product fraction accounting for 0.1 vol% to 20 vol% of the combined volume of at least a portion of the first fractionator product and the pyrolysis product fraction; and at least a first product stream comprising ethylene and a second product stream comprising propylene are separated from the compressed olefin product fraction, the first product stream optionally comprising ethylene, the ethylene being derived from exposing a feedstock comprising a polyolefin mixture to polyolefin pyrolysis conditions, and the second product stream optionally comprising propylene, the propylene being derived from exposing a feedstock comprising a polyolefin mixture to polyolefin pyrolysis conditions.

[0078] Embodiment 2. A method according to embodiment 1, wherein the raw material comprises 0.1 wt% or more of polyvinyl chloride, polyvinylidene chloride, polyamide, polystyrene, polyethylene terephthalate, ethylene vinyl acetate or a combination thereof, and the raw material optionally comprises 0.1 wt% to 35 wt% of polystyrene.

[0079] Embodiment 3. The method described in any one of the above embodiments, i) wherein the raw material contains 0.1wt% to 10wt% (or 0.1wt% to 2.0wt%) of polyvinyl chloride, polyvinylidene chloride or a combination thereof; ii) wherein the raw material contains 0.1wt% to 1.0wt% of polyamide; or iii) a combination of i) and ii), the method optionally also includes: separating the pyrolysis product fraction to form a lower boiling point fraction and a higher boiling point fraction; and sending the lower boiling point fraction to a pollutant removal section to form at least a portion of the pyrolysis product fraction, at least a portion of the pyrolysis product fraction containing a lower chlorine content than the lower boiling point fraction.

[0080] Embodiment 4. The method of any of the above embodiments, wherein the feedstock comprises 0.1 wt% to 10 wt% ethylene vinyl acetate, or wherein the feedstock comprises 0.1 wt% to 10 wt% polyethylene terephthalate, or a combination thereof.

[0081] Embodiment 5. The method of any of the above embodiments, wherein the one or more additional fractionator products comprise naphtha boiling range products, the method further comprising: sending at least a portion of the naphtha boiling range products to the silicon removal section to form a modified naphtha boiling range product.

[0082] Embodiment 6. The method of any of the above embodiments, wherein a) the heated reaction mixture further comprises heat transfer particles, wherein the heat transfer particles optionally comprise calcium oxide, b) the heated reaction mixture further comprises 10 wt% or more steam, or c) a combination of a) and b).

[0083] Embodiment 7. The method of any of the above embodiments, wherein at least a portion of the first fractionator product and the pyrolysis product fraction are quenched in a quench tower before entering the product gas compressor; or wherein at least a portion of the first fractionator product and the pyrolysis product fraction are quenched in a separate quench tower before entering the product gas compressor.

[0084] Embodiment 8. The method of any of the above embodiments, further comprising mixing at least one of the pyrolysis effluent and the pyrolysis product fraction with a quench oil.

[0085] Embodiment 9. The method of any of the above embodiments, wherein the one or more additional fractionator products comprise a bottoms fraction, a tar fraction, a gas oil fraction, or a combination thereof, and the quench oil optionally comprises at least a portion of the gas oil fraction.

[0086] Embodiment 10. The method of any of the above embodiments, further comprising exposing the compressed olefin product fraction to water washing, alkaline washing, amine washing, or a combination thereof to form a washed compressed olefin product fraction, and passing the washed compressed olefin product fraction into a contaminant removal section to form a contaminant-reduced product fraction, wherein separating at least a first product stream comprising ethylene and a second product stream comprising propylene from the compressed olefin product fraction comprises separating the at least first product stream and the second product stream from the contaminant-reduced product fraction.

[0087] Embodiment 11. The method of any of the above embodiments, A) further comprising physically treating a polymer feed to form the feedstock, the polyolefin mixture comprising particles having a median particle size of 3.0 mm or less; B) further comprising forming the feedstock by combining the polymer feed with a solvent, the polyolefin mixture being at least partially solvated by the solvent; or C) a combination of A) and B).

[0088] Embodiment 12. An integrated system for performing polyolefin pyrolysis and steam cracking, comprising: a polyolefin processing section for forming a polyolefin feedstock; a pyrolysis reactor, comprising a pyrolysis inlet and a pyrolysis outlet, the pyrolysis inlet being in fluid communication with the polyolefin processing section; a first separation section, the first separation section comprising a first separation section inlet, a first vapor outlet, and a first solid outlet, the first separation section inlet being in fluid communication with the pyrolysis outlet; a pyrolysis quenching section, the pyrolysis quenching section being in fluid communication with the first vapor outlet; a second separation section, the second separation section comprising a second separation section inlet, a second light material outlet, and a second heavy material outlet, the second separation section inlet being in fluid communication with the pyrolysis quenching section; a steam A cracking reactor comprising a reactor outlet; a primary fractionator comprising one or more fractionator inlets and a plurality of fractionator outlets, the one or more fractionator inlets being fluidly connected to the reactor outlet and the second heavy material outlet; at least one quench tower comprising one or more quench tower inlets and one or more quench tower outlets, the at least one quench tower inlet being fluidly connected to at least one fractionator outlet and the second heavy material outlet; a process gas compressor comprising a compressor inlet and a compressor outlet, the compressor inlet being fluidly connected to the one or more quench tower outlets; and a plurality of olefin separation sections comprising at least an ethylene outlet and a propylene outlet, the plurality of olefin separation sections being fluidly connected to the compressor outlet.

[0089] Embodiment 13. A system according to Embodiment 12, wherein at least one quench tower includes a common quench tower connected to the at least one fractionator outlet and the second heavy material outlet fluid; or wherein the system further comprises a supplemental quench tower connected to the second light material outlet fluid, wherein a process gas compressor is connected to the second light material outlet fluid via the supplemental quench tower, and wherein the compressor outlet of the process gas compressor is connected to the multiple olefin separation section fluids via one or more contaminant removal sections.

[0090] Embodiment 14. A system according to embodiment 12 or 13, wherein the system further comprises a pyrolysis regenerator, the pyrolysis reactor further comprises heat transfer particles, and the pyrolysis reactor and the regenerator are fluidically connected to transfer the heat transfer particles.

[0091] Embodiment 15. A system according to any one of Embodiments 12 to 14, wherein the system further includes a) a silicon removal section connected to the second heavy material outlet fluid; b) a silicon removal section connected to at least one of the multiple fractionator outlets; c) a mercury removal section connected to the compressor outlet fluid, and the multiple olefin separation sections are connected to the compressor outlet fluid via the mercury removal section; or c) a combination of two or more of a), b and c).

[0092] Supplementary Embodiment A. The method of any of Embodiments 1-11, wherein the feedstock is heated at a rate of 200°C / second or more.

[0093] Supplementary embodiment B. The method of any one of embodiments 1-11, wherein C 2 The product stream comprises 90 wt% or more ethylene, or wherein C 3 The product stream comprises 90 wt% or more propylene, or combinations thereof.

[0094] Supplementary Embodiment C. The method of any of Embodiments 1-11, wherein at least a second pyrolysis product fraction is separated from the pyrolysis effluent, the method further comprising passing the second pyrolysis product fraction to a primary fractionator.

[0095] When numerical lower limits and numerical upper limits are listed herein, the range from any lower limit to any upper limit is covered. Although the illustrative embodiments of the present disclosure have been specifically described, it should be understood that various other modifications will be apparent to those skilled in the art and can be easily made by those skilled in the art without departing from the spirit and scope of the present disclosure. Therefore, it is not intended that the scope of the appended claims be limited to the embodiments and descriptions described herein, but rather that the claims be interpreted as covering all features of patentable novelty present in the present disclosure, including all features that would be considered as equivalents by those skilled in the art to which the present disclosure belongs.

[0096] The present disclosure has been described above with reference to many embodiments and specific examples. Based on the above detailed description, many variations will occur to those skilled in the art. All of these obvious variations are within the full intended scope of the appended claims.

Claims

1. A method for pyrolyzing a mixed polyolefin feed, comprising: Exposing a feedstock comprising a polyolefin mixture comprising two or more types of monomers to polyolefin pyrolysis conditions to form a pyrolysis effluent, the polyolefin mixture comprising: heating the raw materials at a rate of 100°C / second or more to form a heated reaction mixture having a temperature of 500°C to 900°C, and cooling the heated reaction mixture to a temperature of less than 500° C. to form a pyrolysis effluent, the heated reaction mixture being at a temperature of 500° C. or greater for 0.1 second to 5.0 seconds; performing an initial separation of the pyrolysis effluent to form at least a pyrolysis product fraction and a fraction comprising solid particles; steam cracking a steam cracker feed to form a steam cracker reactor effluent, wherein the steam cracker feed comprises whole crude oil and fractional crude oil, naphtha boiling feed, distillate boiling range feed, atmospheric residue boiling range feed, vacuum residue boiling range feed, or a combination thereof, and is separated from a mixed polyolefin feed; passing at least a portion of the steam cracker reactor effluent to a primary fractionator to form at least a first fractionator product and one or more additional fractionator products having a higher boiling range than the first fractionator product; passing at least a portion of the first fractionator product and at least a portion of the pyrolysis product fraction to a process gas compressor to form a compressed olefin product fraction, the volume of the pyrolysis product fraction constituting from 0.1 vol% to 20 vol% of the combined volume of at least a portion of the first fractionator product and the pyrolysis product fraction; and At least a first product stream comprising ethylene and a second product stream comprising propylene are separated from the compressed olefin product fraction.

2. The method according to claim 1, wherein the raw material comprises 0.1 wt% or more of polyvinyl chloride, polyvinylidene chloride, polyamide, polystyrene, polyethylene terephthalate, ethylene vinyl acetate or a combination thereof.

3. A process according to any one of the preceding claims, wherein the feedstock comprises from 0.1 wt% to 35 wt% polystyrene.

4. The method of claim 1 or claim 2, i) wherein the feedstock comprises 0.1 wt% to 10 wt% of polyvinyl chloride, polyvinylidene chloride or a combination thereof; ii) wherein the feedstock comprises 0.1 wt% to 1.0 wt% of polyamide; or iii) a combination of i) and ii).

5. The method according to claim 4, further comprising: separating the pyrolysis product fraction to form a lower boiling point fraction and a higher boiling point fraction; and The lower boiling point fraction is passed to a contaminant removal section to form at least a portion of a pyrolysis product fraction, at least a portion of which comprises a lower chlorine content than the lower boiling point fraction.

6. The process of claim 5 wherein the lower boiling fraction is a vapor and the contaminant removal stage comprises a water wash for chlorine removal, a supplemental quench tower for cooling the lower boiling fraction and chlorine removal can be achieved based on controlling the pH of the water used in the quench tower.

7. The method of claim 1 or claim 2, wherein the feedstock comprises 0.1 wt% to 10 wt% ethylene vinyl acetate, or wherein the feedstock comprises 0.1 wt% to 10 wt% polyethylene terephthalate, or a combination thereof.

8. The process of claim 1 or claim 2, a) wherein the first product stream comprises ethylene derived by exposing a feedstock comprising a mixture of polyolefins to polyolefin pyrolysis conditions; b) wherein the second product stream comprises propylene derived by exposing a feedstock comprising a mixture of polyolefins to polyolefin pyrolysis conditions; or c) a combination of a) and b).

9. The process of claim 1 or claim 2, wherein the one or more additional fractionator products comprise naphtha boiling range products, the process further comprising: At least a portion of the naphtha boiling range product is passed to a silicon removal zone to form a modified naphtha boiling range product.

10. The method of claim 1 or claim 2, wherein the heated reaction mixture further comprises heat transfer particles and the polyolefin pyrolysis conditions further comprise exposing the feedstock to the heat transfer particles.

11. The method of claim 10, wherein the heat transfer particles comprise calcium oxide, at least a portion of which is converted to calcium chloride under the polyolefin pyrolysis conditions.

12. The method of claim 11, wherein the fraction containing solid particles comprises heat transfer particles and calcium chloride, and the polyolefin pyrolysis conditions further comprise: recycling a first portion of the fraction comprising solid particles to a pyrolysis reactor; and A second portion of the fraction comprising solid particles is purged.

13. The method of claim 1, wherein the heated reaction mixture further comprises 10 wt% or more steam.

14. The process of claim 1 or claim 2, wherein at least a portion of the first fractionator product and the pyrolysis product fraction are quenched in a quench tower prior to being passed into a product gas compressor, or wherein at least a portion of the first fractionator product and the pyrolysis product fraction are quenched in separate quench towers prior to being passed into a product gas compressor.

15. The method according to claim 1 or claim 2, further comprising: exposing the compressed olefin product fraction to a water wash, a base wash, an amine wash, or a combination thereof to form a washed compressed olefin product fraction, and passing the washed compressed olefin product fraction to a contaminant removal section to form a contaminant-reduced product fraction, Wherein separating at least a first product stream comprising ethylene and a second product stream comprising propylene from the compressed olefin product fraction comprises separating at least the first product stream and the second product stream from the contaminant-reduced product fraction.

16. The process of claim 1 or claim 2, wherein the one or more additional fractionator products comprises a bottoms fraction, a tar fraction, or a combination thereof.

17. The method of claim 1 or claim 2, further comprising mixing at least one of the pyrolysis effluent and the pyrolysis product fraction with a quench oil.

18. The process of claim 17, wherein the one or more further fractionator products comprises a gas oil fraction and the quench oil comprises at least a portion of the gas oil fraction.

19. The method of claim 1 or claim 2, wherein a second pyrolysis product fraction is separated from the pyrolysis effluent, the method further comprising passing the second pyrolysis product fraction to a primary fractionator.

20. The process of claim 1 or claim 2, wherein the first product stream comprises 90 wt% or more ethylene, or wherein the second product stream comprises 90 wt% or more propylene, or a combination thereof.

21. The method of claim 1 or claim 2, further comprising physically treating the polymer feed to form the feedstock, the polyolefin mixture comprising particles having a median particle size of 3.0 mm or less.

22. The method of claim 1 or claim 2, further comprising forming the feedstock by combining the polymer feed with a solvent, the polyolefin mixture being at least partially solvated by the solvent.

23. An integrated system for performing the method of any one of claims 1 to 22, comprising: a polyolefin processing section for forming a polyolefin feedstock; a pyrolysis reactor including a pyrolysis inlet and a pyrolysis outlet, the pyrolysis inlet being in fluid communication with the polyolefin processing section; a first separation stage comprising a first separation stage inlet, a first vapor outlet, and a first solids outlet, the first separation stage inlet being in fluid communication with the pyrolysis outlet; a pyrolysis quench section in fluid communication with the first vapor outlet; A second separation section including a second separation section inlet, a second light matter outlet, and a second heavy matter outlet, wherein the second separation section inlet is in fluid communication with the pyrolysis quenching section; a steam cracking reactor including a reactor outlet; a primary fractionator comprising one or more fractionator inlets and a plurality of fractionator outlets, the one or more fractionator inlets being in fluid communication with the reactor outlet and the second heavies outlet; at least one quench tower comprising one or more quench tower inlets and one or more quench tower outlets, the at least one quench tower inlet being in fluid communication with the at least one fractionator outlet and the second heavies outlet; a process gas compressor including a compressor inlet and a compressor outlet, the compressor inlet being in fluid communication with the one or more quench tower outlets; and A plurality of olefin separation sections including at least an ethylene outlet and a propylene outlet are fluidly connected to the compressor outlet.

24. The system of claim 23, wherein the at least one quench tower comprises a common quench tower in fluid communication with the at least one fractionator outlet and the second heavies outlet.

25. The system of claim 23, further comprising a supplemental quench tower in fluid communication with the second lights outlet, wherein the process gas compressor is in fluid communication with the second lights outlet via the supplemental quench tower.

26. The system of claim 25, wherein a compressor outlet of the process gas compressor is in fluid communication with a plurality of olefin separation stages via one or more contaminant removal stages.

27. The system of claim 23, wherein the system further comprises a pyrolysis regenerator, the pyrolysis reactor further comprises heat transfer particles, and the pyrolysis reactor and the regenerator are in fluid communication for transfer of the heat transfer particles.

28. The system of claim 27, wherein the pyrolysis reactor further comprises calcium oxide particles.

29. The system of claim 23, further comprising a) a silicon removal section in fluid communication with the second heavies outlet; b) a silicon removal section in fluid communication with at least one of a plurality of fractionator outlets; c) a mercury removal section in fluid communication with a compressor outlet, a plurality of olefin separation sections being in fluid communication with the compressor outlet via the mercury removal section; or c) a combination of two or more of a), b, and c).

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