High pressure polymerization system and high pressure polymerization process for polymerization of ethylenically unsaturated monomers

Abstract

The invention discloses a high-pressure polymerization system. The present invention relates to a high pressure polymerization system comprising: a) a continuously operable polymerization reactor having a reactor inlet and a reactor outlet, and b) a reactor blow-down system adapted and arranged in fluid communication with the polymerization reactor, the reactor blow-down system comprising: b1) a reactor blow-down vessel adapted and arranged in fluid communication with the polymerization reactor, the emptying container of the reactor contains a water-based quenching medium; b2) one or more release lines connecting the polymerization reactor with the reactor blow-down vessel and comprising a release line outlet for expanding contents of the high pressure polymerization system comprising a polymer and a gaseous component into the reactor blow-down vessel, wherein the release line outlet is located above the maximum level of the aqueous quench medium, and wherein the one or more release lines are provided with a rupture disk, the rupture disk automatically allows the contents of the high pressure polymerization system to enter the reactor blow-down vessel through the one or more release lines.

Description

Technical Field

[0001] This disclosure relates to a high-pressure polymerization system for the polymerization of olefinic unsaturated monomers and a high-pressure polymerization method for polymerizing olefinic unsaturated monomers in a high-pressure polymerization system comprising a continuously operating polymerization reactor to obtain ethylene-based polymers. Background Technology

[0002] Polyethylene is the most widely used commercial polymer. It can be prepared by several different methods. Polymerization under high pressure in the presence of a free radical initiator was the first method discovered to obtain polyethylene and continues to be a valuable method with high commercial relevance for the preparation of low-density polyethylene (LDPE).

[0003] Besides polymerization reactors, which can be autoclaves, tubular reactors, or combinations thereof, common equipment configurations for facilities producing low-density polyethylene include other devices. To pressurize the reaction components, a set of two compressors, a primary compressor and a secondary compressor, sometimes referred to as a super compressor, is typically used. At the end of the polymerization sequence, the high-pressure polymerization unit usually further includes equipment for granulating the resulting polymer, such as extruders and granulators. Furthermore, such polymerization units typically include systems for feeding monomers and comonomers, radical initiators, modifiers, or other substances into the polymerization reaction at one or more locations. Facilities for producing polyethylene are regularly constructed in a manner designed for continuous operation for extended periods without any signs of fatigue, thus typically allowing for fairly long maintenance intervals.

[0004] The polymerization process in the LDPE reactor is carried out under pressures reaching up to 350 MPa. Such high pressures require specialized techniques to handle the process safely and reliably. It is known that under certain temperature and pressure conditions, ethylene can rapidly decompose explosively, yielding soot, methane, and hydrogen. This is associated with a dramatic increase in pressure and temperature. Decomposition temperatures can become excessively high (>1000°C), posing a considerable potential risk to the operational safety of the production facility. For example, temperatures reached during such decomposition events can damage reactor tubes, potentially leading to austenitization of the tube metal. At austenitizing temperatures, if the material is rapidly cooled, martensite forms in the reactor tubes. Martensite is the hardest and most brittle of the various microstructures found in carbon steel.

[0005] Therefore, during emergency venting, it is considered necessary to rapidly remove the hot gases generated by decomposition and to rapidly reduce the pressure.

[0006] According to WO 2017 / 098389 A1, rapid removal of such hot gases should be achieved through a unidirectional venting system comprising a front emergency vent valve located downstream of the supercompressor discharge and at the front end of the reactor, and at least one additional valve at the rear end of the reactor. Here, the system should prevent the reactor walls from reaching temperatures capable of austenitizing the tubular metal, achieved by maintaining flow in a single direction away from the supercompressor during the venting process, and by maintaining specific pressures and flow rates within the reactor during venting. In this way, heat transfer to the tubular reactor should be minimized.

[0007] In the event of decomposition, the pressure and temperature in the reactor may rise too rapidly, making it possible that emergency venting valves or pressure relief valves are insufficient to counteract the decomposition and reduce the pressure of the high-pressure polymerization system in a short period of time.

[0008] Therefore, there is a continuous need for improved ethylene polymerization methods in high-pressure polymerization systems that enable faster and safer quenching of hot gases in the event of shutdowns caused by disturbances in the polymerization process, such as temperature and / or pressure rises exceeding safety thresholds. Summary of the Invention

[0009] This disclosure provides a high-pressure polymerization system, the high-pressure polymerization system comprising:

[0010] a) A polymerization reactor capable of continuous operation, the polymerization reactor having a reactor inlet and a reactor outlet, and

[0011] b) A reactor venting system adapted and arranged in fluid communication with the polymerization reactor, the reactor venting system comprising:

[0012] b1) Reactor vent container containing an aqueous quenching medium.

[0013] b2) One or more release lines connecting the polymerization reactor to the reactor vent container and including a release line outlet for expanding the contents of the high-pressure polymerization system, comprising polymer and gaseous components, into the reactor vent container, wherein the release line outlet is located above the maximum level of the aqueous quenching medium, and

[0014] One or more of the release lines are equipped with rupture discs. If the pressure in the reactor exceeds a predetermined pressure threshold, the rupture discs automatically allow the contents of the high-pressure polymerization system, especially the contents of the polymerization reactor, to enter the reactor venting container through the one or more release lines.

[0015] In some embodiments, the one or more release lines are divided into at least two arms, which are preferably connected to the reactor vent container on opposite sides. The one or more release lines may be specifically connected to the reactor vent container diametrically with each other.

[0016] In some embodiments, the predetermined pressure threshold can be about 10 to 700 bar less than the design pressure of the reactor, preferably 100 to 600 bar less, and more preferably 200 to 500 bar less.

[0017] In some embodiments, the total area of ​​the rupture discs installed per reactor volume can be about 0.003 to 0.050 m² / m³, preferably 0.004 to 0.025 m² / m³, and more preferably 0.005 to 0.017 m² / m³.

[0018] In some embodiments, the number of rupture discs is about 1 to 9, preferably 1 to 6, and more preferably 2 to 4.

[0019] In some embodiments, the reactor is an autoclave reactor or a combination of an autoclave reactor and a tubular reactor.

[0020] In some embodiments, the rupture disc is disposed on a replaceable module forming the end of one or more release lines.

[0021] In some embodiments, one or more release lines extend into the radial opening of the reactor.

[0022] In some embodiments, one or more release lines protrude into the reactor. In this case, the one or more release lines may also serve as supports for the central bearing of the agitator shaft. For example, the central bearing may include hooks attached to the ends of the release lines. Preferably, the rupture disc is arranged at the ends of the respective release lines and can therefore be arranged inside the reactor volume.

[0023] In some embodiments, the front surface of the rupture disc facing the reactor volume is substantially flush with the inner surface of the reactor wall. The rupture disc can, for example, close the radial opening of the reactor and be flush with the inner reactor wall. In particular, the rupture disc can be positioned at the end of the release line that connects to the reactor.

[0024] In some embodiments, a stirrer may be provided, which is coaxially mounted in the reactor, wherein the stirrer is fixed to one or more release lines, or an assembly of one or more release lines protrudes into the reactor.

[0025] In some embodiments, the polymerization system may further include at least one second release line, which is provided with one or more first emergency valves adapted to open and close the fluid communication between the polymerization reactor and the reactor venting system.

[0026] In some embodiments, the at least one second release line may be located downstream of the reactor and connected to the reactor outlet.

[0027] In some embodiments, the reactor vent vessel has a substantially circular design above a main portion P, the main portion P having a length L, a diameter D, and an L / D ratio in the range of 1.75 to 10.0.

[0028] In some embodiments, the release line or the arm of the release line each has a connector having a central axis and arranged such that the angle (α) formed between the central axis of the connector and a tangent located at the intersection of the central axis and the circular periphery of the main part P of the reactor venting container and having the same inclination as the central axis relative to the horizontal plane containing the intersection is in the range of 5° to 70°.

[0029] In some embodiments, the coupling is arranged substantially tangentially relative to the horizontal circumference of the main portion P.

[0030] In some embodiments, the reactor vent container further includes a ventilation riser containing a contraction section.

[0031] In some embodiments, the coupling is tilted downwards such that the flow of the contents of the high-pressure polymerization system, which includes polymers and gaseous components, is directed toward the surface of the aqueous quenching medium in the reactor venting container.

[0032] In some embodiments, at the location where the central axis intersects the horizontal circumference of the main portion P, the angle (β) between the central axis of the joint and the horizontal plane passing through the main portion P of the reactor venting container is in the range of 3° to 89°.

[0033] In some embodiments, multiple release lines connect the polymerization reactor to the reactor venting container.

[0034] In some embodiments, a plurality of fittings at the outlet of the release line connecting the polymerization reactor to the reactor venting container are located at the same horizontal position on the main portion P of the reactor venting container, and / or wherein the plurality of fittings at the outlet of the release line connecting the polymerization reactor to the reactor venting container are equidistantly or uniformly distributed on the circumference of the main portion P of the reactor venting container.

[0035] In some embodiments, a first set of fittings for the outlet of the release line connecting the polymerization reactor to the reactor venting container is located at the same horizontal position on the main portion P of the reactor venting container, wherein at least one second set of fittings for the outlet of the release line connecting the polymerization reactor to the reactor venting container is horizontally aligned on the main portion P of the reactor venting container at a horizontal position different from that of the first set of fittings.

[0036] In some embodiments, the high-pressure polymerization system further includes:

[0037] c) Pressure control valve,

[0038] d) Post-reactor cooler, and

[0039] e) Separating containers or a series of separating containers

[0040] The post-reactor cooler is in fluid communication with the continuously operating polymerization reactor via a first connecting line, the separation vessel or series of separation vessels is in fluid communication with the post-reactor cooler via a second connecting line, and the pressure control valve is adapted and arranged to control the fluid communication between the continuously operating polymerization reactor and the post-reactor cooler.

[0041] In some embodiments, the ventilation riser is a vertical pipe with an inner diameter of 0.4m to 1.4m, and the constricted section of the ventilation riser has a smaller inner diameter such that the cross-sectional area of ​​the opening at the constricted section is 10% to 60% of the cross-sectional area of ​​the opening of the vertical pipe.

[0042] In some embodiments, the release line connecting the polymerization reactor to the reactor venting container is heated to a temperature of 160°C to 240°C.

[0043] In some embodiments, the reactor venting system further includes:

[0044] b4) Nitrogen coverage system and / or

[0045] b5) Fill level control system.

[0046] In some embodiments, the reactor venting system further includes:

[0047] b6) A reactor venting and unloading vessel, which is arranged and adapted to be in fluid communication with the reactor venting vessel, and

[0048] b7) At least one discharge valve in the fluid communication between the reactor vent container and the reactor vent discharge container, and adapted and arranged to open or close the fluid communication between the reactor vent container and the reactor vent discharge container.

[0049] The reactor vent container is installed above the reactor venting and unloading container.

[0050] This disclosure also provides a method for polymerizing ethylene and optionally one or more comonomers in a high-pressure polymerization system as defined above to obtain an ethylene-based polymer, the method comprising:

[0051] A) Monitor the occurrence of disturbances in the high-pressure polymerization system, and

[0052] B) If the predetermined pressure threshold is exceeded, the contents of the reactor will be automatically released into the reactor vent container;

[0053] C) Contacting the contents of the vented container of the reactor with an aqueous quenching medium to obtain an aqueous polymer slurry; and

[0054] D) Separate the aqueous polymer slurry and the gaseous component.

[0055] In some embodiments, the method further includes:

[0056] E) Transfer the aqueous polymer slurry to the reactor venting and unloading container by opening at least one discharge valve.

[0057] In some embodiments, steam is injected into the reactor venting vessel in the event of a disturbance or a temporary deviation from the disturbance.

[0058] In some embodiments, steam injection is paused approximately 120 to 300 seconds after a disturbance occurs. Attached Figure Description

[0059] To assist those skilled in the art in making and using the subject matter of this disclosure, reference is made to the accompanying drawings, in which:

[0060] Figure 1 A schematic apparatus structure of a high-pressure polymerization system according to an exemplary embodiment of the present disclosure is shown;

[0061] Figure 2 A schematic apparatus structure is shown, in which the polymerization reactor is connected to the reactor venting vessel via a release line;

[0062] Figure 3 The apparatus structure of the reactor venting system of this disclosure is schematically shown. Detailed Implementation

[0063] This disclosure provides a high-pressure polymerization system, the high-pressure polymerization system comprising:

[0064] a) A polymerization reactor capable of continuous operation, the polymerization reactor having a reactor inlet and a reactor outlet, and

[0065] b) A reactor venting system adapted and arranged to be in fluid communication with the polymerization reactor.

[0066] This disclosure also provides a method for polymerizing ethylene and optionally one or more comonomers in the high-pressure polymerization system to obtain ethylene-based polymers. This method allows for automatic and efficient quenching of the reactor contents, containing hot ethylene and hot polymers, in the event of disturbances (e.g., decomposition).

[0067] In a preferred embodiment of this high-pressure polymerization system, the monomer is brought to polymerization pressure in a series of compression stages by one or more compressors. The compressed monomer optionally passes through a preheater or precooler and is then transferred to the polymerization reactor at the reactor inlet. Furthermore, the reaction mixture obtained through polymerization exits the reactor at the reactor outlet via a pressure control valve and is optionally cooled by a post-reactor cooler. Subsequently, the reaction mixture is separated into polymeric and gaseous components in two or more stages. The gaseous component separated in the first stage at an absolute pressure of 15 MPa to 50 MPa is recirculated to one or more compressors via a high-pressure gas recirculation line, and the gaseous component separated in the second stage at an absolute pressure in the range of 0.1 MPa to 0.5 MPa is recirculated to the first stage of the series of compression stages via a low-pressure gas recirculation line. The polymeric component obtained through polymerization is then converted into pellets.

[0068] Therefore, in a preferred embodiment, the high-pressure polymerization system further includes:

[0069] c) Pressure control valve,

[0070] d) Post-reactor cooler, and

[0071] e) Separating containers or a series of separating containers

[0072] The post-reactor cooler is in fluid communication with the continuously operating polymerization reactor via a first connecting line, the separation vessel or series of separation vessels is in fluid communication with the post-reactor cooler via a second connecting line, and the pressure control valve is adapted and arranged to control the fluid communication between the continuously operating polymerization reactor and the post-reactor cooler.

[0073] It should be understood that the use of "and / or" is defined inclusively, such that the term "a and / or b" should be understood to include the set of: "a and b", "a or b", "a", and "b". Preferably, "and" in most cases "a and / or b" refers to two entities "a" and "b", at least one of which exists in the described embodiments.

[0074] The polymerization is preferably a homopolymerization of ethylene or a copolymerization of ethylene with one or more other monomers, provided that these monomers are capable of copolymerizing with ethylene radicals under high pressure. Examples of copolymerizable monomers used in this technology are α,β-unsaturated C3-C8-carboxylic acids and derivatives of α,β-unsaturated C3-C8-carboxylic acids, such as unsaturated C3-C8... 15 -Carboxylic acid esters or anhydrides, and 1-olefins. In addition, vinyl carboxylic acid esters (such as vinyl acetate) can be used as comonomers. Propylene, 1-butene, 1-hexene, acrylic acid, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, vinyl acetate, or vinyl propionate are particularly suitable as comonomers.

[0075] In the case of copolymerization, based on the amount of monomers, i.e., the sum of ethylene and other monomers, the proportion of one or more comonomers in the reaction mixture is from 1% to 50% by weight, preferably from 3% to 40% by weight. Depending on the type of comonomer, it is preferable to feed the comonomer to the reactor device at more than one point. Preferably, the comonomer is fed to the suction side of the secondary compressor.

[0076] For the purposes of this disclosure, the polymer or polymeric material is a substance composed of at least two monomeric units. The polymer or polymeric material is preferably low-density polyethylene having an average molecular weight Mn greater than 20,000 g / mol. The term "low-density polyethylene" (LDPE) includes ethylene homopolymers and ethylene copolymers. The methods of this disclosure can also be used to prepare polymers with a molecular weight Mn less than 20,000 g / mol. n Oligomers, waxes and polymers.

[0077] The method of this disclosure is preferably a free radical polymerization carried out in the presence of a free radical polymerization initiator. Possible initiators for starting polymerization in the respective reaction zones are generally any substance that can generate free radicals under the conditions in the polymerization reactor, such as oxygen, air, azo compounds, or peroxide polymerization initiators. In a preferred embodiment of this disclosure, polymerization is carried out using oxygen in the form of pure O2 or as air feed. In the case of oxygen-initiated polymerization, the initiator is typically first mixed with the ethylene feed and then fed into the reactor. In this case, not only can a stream containing monomers and oxygen be fed to the beginning of the polymerization reactor, but it can also be fed to one or more points along the reactor, thereby creating two or more reaction zones. Initiation using organic peroxides or azo compounds also represents a preferred embodiment of this disclosure. Individual initiators or, preferably, mixtures of various initiators can be used. A wide range of initiators, particularly peroxides, are commercially available, for example, under the trade name Trigonox. ® Or Perkadox ® The products provided by Nouryon.

[0078] In polymerization, the molecular weight of the polymer to be prepared can be altered as usual by adding a modifier that acts as a chain transfer agent. Examples of modifiers used in this technique are hydrogen, aliphatic hydrocarbons, and olefins, such as propane, butane, pentane, hexane, cyclohexane, propylene, 1-butene, 1-pentene, or 1-hexene, ketones (such as acetone, methyl ethyl ketone (2-butanone), methyl isobutyl ketone, methyl isopentyl ketone, diethyl ketone, or dipentyl ketone), aldehydes (such as formaldehyde, acetaldehyde, or propionaldehyde), and saturated aliphatic alcohols (such as methanol, ethanol, propanol, isopropanol, or butanol). Saturated aliphatic aldehydes, particularly propionaldehyde, or 1-olefins (such as propylene, 1-butene, or 1-hexene) or aliphatic hydrocarbons (such as propane) are particularly preferred.

[0079] Polymerization is preferably carried out at a pressure of 110 MPa to 500 MPa. For polymerization in a tubular reactor, a pressure of 160 MPa to 350 MPa is more preferred, and a pressure of 200 MPa to 330 MPa is particularly preferred. For polymerization in an autoclave reactor, a pressure of 110 MPa to 300 MPa is more preferred, and a pressure of 120 MPa to 280 MPa is particularly preferred. For polymerization in a tubular reactor, the polymerization temperature is preferably in the range of 100°C to 350°C, and more preferably in the range of 180°C to 340°C, and particularly preferably in the range of 200°C to 330°C. For polymerization in an autoclave reactor, a temperature of 110°C to 320°C is more preferred, and particularly preferably in the range of 120°C to 310°C is particularly preferred.

[0080] Polymerization can be carried out using all types of high-pressure reactors suitable for high-pressure polymerization, having both a reactor inlet and a reactor outlet. The high-pressure reactor used in this technology is, for example, a tubular reactor or an autoclave reactor. Preferably, polymerization is carried out in one or more autoclave reactors or a combination of an autoclave reactor and a tubular reactor. In a particularly preferred embodiment of this disclosure, the polymerization reactor is an autoclave reactor.

[0081] Common autoclave reactors are stirred reactors and have an aspect ratio in the range of 2 to 30, preferably in the range of 2 to 20. Such autoclave reactors have one or more reaction zones, preferably 1 to 6, more preferably 1 to 4. The number of reaction zones depends on the number of agitator baffles that separate the various mixing zones within the autoclave reactor. In high-pressure polymerization systems in which polymerization or the first polymerization takes place in an autoclave reactor—that is, in high-pressure polymerization systems where the sole polymerization reactor is an autoclave reactor or in high-pressure polymerization systems where the first reactor in a series of reactors is an autoclave reactor—the reaction mixture from the compressor typically passes through a precooler before entering the autoclave reactor.

[0082] The compression of the reactant gas composition to polymerization pressure is carried out by one or more compressors in a series of compression stages, wherein preferably, a main compressor first compresses the reactant gas composition to a pressure of 10 MPa to 50 MPa, and a secondary compressor further compresses the reactant gas composition to a polymerization pressure of 110 MPa to 500 MPa. Preferably, the main and secondary compressors are multi-stage compressors. It is also possible to separate one or more stages of one or two of these compressors and divide these stages into separate compressors. However, it is common practice to use a series of one main compressor and one secondary compressor to compress the reactant gas composition to polymerization pressure. In this case, sometimes the entire main compressor is designated as the main compressor. However, it is also common practice to designate one or more first stages of the main compressor (which compresses the recirculated gas from the low-pressure product separator to the pressure of the fresh ethylene feed) as booster compressors, and then only one or more subsequent stages are designated as main compressors, although the booster compressor and the subsequent stages are all part of a single unit.

[0083] In a preferred embodiment of this disclosure, the high-pressure polymerization system includes a preheater upstream of the reactor for heating the reactant gas composition to a temperature capable of initiating polymerization. In a preferred embodiment of this disclosure, the entire reactant gas composition supplied by the secondary compressor is fed to the reactor inlet via the preheater.

[0084] In addition to the polymerization reactor and reactor venting system, the high-pressure polymerization system used for carrying out the polymerization of this disclosure preferably includes two or more gas recirculation lines for recycling unreacted monomers into the polymerization process. The reaction mixture obtained in the polymerization reactor is transferred to a first separation vessel, commonly referred to as a high-pressure product separator, and separated into gaseous and liquid fractions at an absolute pressure of 15 MPa to 50 MPa. The gaseous fraction taken from the first separation vessel is fed to the suction side of a secondary compressor via the high-pressure gas recirculation lines. In the high-pressure gas recirculation lines, the gas is typically purified through several purification steps to remove unwanted components, such as entrained polymers or oligomers. The liquid fraction taken from the first separation vessel (which typically still contains 20% to 40% by weight of dissolved monomers (such as ethylene) and comonomers) is transferred to a second separation vessel (commonly referred to as a low-pressure product separator) and further separated into polymeric and gaseous components under reduced pressure, typically in the range of 0.1 MPa to 0.5 MPa. The gaseous fraction taken from the second separation vessel is fed to the main compressor via a so-called low-pressure gas recirculation line, preferably to the first stage. Furthermore, the low-pressure gas recirculation line typically includes several purification steps to remove unwanted components from the gas. The high-pressure polymerization system may further include additional separation steps for separating additional gaseous fractions from the reaction mixture and additional gas recirculation lines for feeding such additional gaseous fractions containing unreacted monomers to one of the compressors, for example, between the first separation step and the second separation step operating at intermediate pressure.

[0085] Preferably, the recirculated gas from the low-pressure gas recirculation line is compressed to the pressure of the fresh feed of the olefinic unsaturated monomer (preferably ethylene) via the first stage of the main compressor, and then combined with the fresh gas feed, and the combined gas is further compressed to a pressure of 10 MPa to 50 MPa in the main compressor. Preferably, the main compressor includes five or six compression stages: two or three compression stages before the introduction of fresh gas, and two or three compression stages after the introduction of fresh gas. The secondary compressor preferably has two stages: a first stage that compresses the gas to a pressure in the range of 50 MPa to 150 MPa, and a second stage that further compresses the gas to the final polymerization pressure.

[0086] The pressure within the polymerization reactor is preferably controlled by a pressure control valve located at the reactor outlet, through which the reaction mixture exits the reactor. The pressure control valve can be any valve device suitable for reducing the pressure of the reaction mixture exiting the reactor to the pressure within the first separation vessel.

[0087] In a preferred embodiment of this disclosure, the high-pressure polymerization system includes a post-reactor cooler downstream of the polymerization reactor for cooling the reaction mixture. The post-reactor cooler may be arranged upstream of the pressure control valve or downstream of the pressure control valve. Preferably, the post-reactor cooler is arranged downstream of the pressure control valve.

[0088] The preferred polymerization reactor is located in a chamber with surrounding protective walls.

[0089] The polymer components obtained through polymerization are typically ultimately converted into pellets using equipment such as extruders or granulators. Preferably, the ethylene-based polymer produced by this method has a content of 0.910 g / cm³. 3 Up to 0.960 g / cm 3 The density is within the range of 0.910 g / cm³ to 0.940 g / cm³, preferably LDPE.

[0090] In addition to the polymerization reactor capable of continuous operation, the method disclosed herein includes:

[0091] b) A reactor venting system adapted and arranged in fluid communication with the polymerization reactor, the reactor venting system comprising:

[0092] b1) Reactor vent container containing an aqueous quenching medium;

[0093] b2) One or more release lines connecting the polymerization reactor to the reactor vent container and including a release line outlet for expanding the contents of the high-pressure polymerization system, comprising polymer and gaseous components, into the reactor vent container, wherein the release line outlet is located above the maximum level of the aqueous quenching medium.

[0094] One or more of the release lines are equipped with rupture discs. If the pressure in the reactor exceeds a predetermined pressure threshold, the rupture discs automatically allow the contents of the high-pressure polymerization system to enter the reactor vent container through one or more release lines.

[0095] In a preferred embodiment, the reactor vent container has a substantially circular design above the main portion P, which has a length L, a diameter D, and an L / D ratio in the range of 1.75 to 10.0, preferably in the range of 2.0 to 6.0, and particularly in the range of 2.0 to 4.0.

[0096] Each release line may have a connector that connects it to the main part P of the reactor vent container. Typically, the connector has a tubular, particularly cylindrical, hollow space through which gaseous and polymeric materials can enter the reactor vent container. The central axis passes through this tubular, particularly hollow space. The connector has a central axis and is arranged such that the angle (α) formed between the central axis of the connector and a tangent located at the intersection of the central axis and the circular periphery of the main part P of the reactor vent container, and having the same inclination as the central axis relative to the horizontal plane containing the intersection point, is in the range of 5° to 70°, preferably in the range of 10° to 60°, and more preferably in the range of 15° to 50°.

[0097] In a preferred embodiment of this disclosure, one of the joints, or a plurality of joints, or all of the joints, and preferably all of the joints are arranged substantially tangentially relative to the horizontal circumference of the main portion P.

[0098] In a preferred embodiment of this disclosure, one of the joints, or a plurality of joints, or all of the joints, and preferably all of the joints, is inclined downward such that the flow of the contents of the high-pressure polymerization system, comprising the polymer and gaseous components, is directed toward the surface of the aqueous quenching medium in the reactor venting vessel.

[0099] In a preferred embodiment of this disclosure, one of the joints, or a plurality of joints, or all of the joints, and preferably all of the joints, at the location where the central axis intersects the horizontal circumference of the main portion P, has an inclination angle (β) in the range of 3° to 89°, and preferably in the range of 5° to 45°, between the central axis of the joint and the horizontal plane passing through the main portion P of the reactor venting container.

[0100] Fluid communication between the polymerization reactor and the reactor venting system can be provided via one or more release lines. Preferably, multiple release lines connect the polymerization reactor to the reactor venting vessel. In this case, each release line may include a rupture disc that automatically ruptures when a predetermined pressure threshold is exceeded in the reactor.

[0101] At least one release line can be split into two arms, each arm having a connector that connects the release line to the main portion P of the reactor vent container. Preferably, these arms are connected to the main portion P on opposite sides. In this embodiment, high-pressure fluid transferred from the reactor to the reactor vent container via a single release line can be diverted and enter the reactor vent container from different sides. Therefore, fluid will not enter the reactor vent container from one side, which would result in a strong force acting on the reactor vent container from said side. However, if the flow is diverted and the fluid enters the reactor vent container from opposite sides, the forces can cancel each other out, resulting in reduced stress in the reactor vent container.

[0102] In a preferred embodiment of this disclosure, multiple or all of the connections at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are located at the same horizontal position on the main portion P of the reactor venting vessel. Alternatively or particularly additionally, multiple or all of the connections at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are equidistantly or uniformly distributed on a particularly horizontal circumference of the main portion P of the reactor venting vessel. In another embodiment, it is also possible that not all but only a limited set of connections at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are uniformly or equidistantly distributed on a particularly horizontal circumference of the main portion P of the reactor venting vessel.

[0103] In a preferred embodiment of this disclosure, a plurality of connectors at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are equidistantly or uniformly distributed on the circumference of the main portion P of the reactor venting vessel. Preferably, all connectors at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are equidistantly or uniformly distributed on the circumference of the main portion P of the reactor venting vessel. In another embodiment, it is also possible that not all but only a limited set of connectors at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are uniformly or equidistantly distributed on the particularly horizontal circumference of the main portion P of the reactor venting vessel.

[0104] In a particularly preferred embodiment of this disclosure, multiple or all of the fittings at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are arranged in two or more sets of fittings located at two or more horizontal positions. In these embodiments, a first set of fittings at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel is located at the same horizontal position on the main portion P of the reactor venting vessel, wherein preferably, multiple first sets of fittings are equidistantly or uniformly distributed on the circumference of the main portion P of the reactor venting vessel, and at least one second set of fittings, preferably, the remaining fittings at the outlet of the release line connecting the polymerization reactor and the reactor venting vessel are horizontally aligned on the main portion P of the reactor venting vessel at a horizontal position different from the horizontal position of the first set of fittings, wherein preferably, multiple second sets of fittings are equidistantly or uniformly distributed on the circumference of the main portion P of the reactor venting vessel. In some other embodiments, it is even preferred that not all of the first or second sets of joints, or all of the joints in the first and second sets of joints, belong to those joints that are uniformly or equidistantly distributed on the circumference of the main part P of the reactor venting vessel, but only a reduced number of these joints.

[0105] In a preferred embodiment of this disclosure, the release line connecting the polymerization reactor to the reactor venting vessel is heated. Preferably, the release line is heated along its entire length, including the connection. The release line is preferably heated to a temperature of 160°C to 240°C, and more preferably to a temperature of 180°C to 220°C. Heating can be performed electrically, preferably by heating with medium-pressure steam, and more preferably by conveying medium-pressure steam through a heating jacket.

[0106] To prevent damage to the reactor, the predetermined pressure threshold at which the rupture disc ruptures can be approximately 10 to 700 bar lower than the reactor's design pressure, preferably 100 to 600 bar lower, and more preferably 200 to 500 bar lower. The reactor's design pressure is typically known and specifies the maximum pressure the reactor can withstand. Therefore, the design pressure is a parameter provided by the original equipment manufacturer (OEM).

[0107] When the total area of ​​the rupture discs installed per reactor volume is about 0.003 to 0.050 m² / m³, preferably 0.004 to 0.025 m² / m³, and more preferably 0.005 to 0.017 m² / m³, rapid decompression can be achieved, especially for large reactors. Preferably, the number of rupture discs installed per reactor is about 1 to 8, preferably 1 to 6, and more preferably 2 to 4. Each release line may include a single rupture disc. Preferably, the rupture disc is formed at the end of the release line near the reactor. When the rupture disc is intact, it can preferably cover the inlet of the release line to prevent reactor contents from entering the release line. However, once the rupture disc ruptures when a predetermined pressure threshold is reached, the reactor contents can immediately enter the release line and flow into the reactor vent container. By utilizing the specific total area of ​​the rupture discs installed per reactor volume, it can be ensured that the reactor can depressurize from a predetermined pressure threshold to 100 MPa in less than 10 seconds, preferably less than 8 seconds, and more preferably in 0.1 to 5 seconds. In particular, the reactor can be designed to depressurize from the predetermined pressure threshold to approximately 30 MPa in 0.1 to 30 seconds, preferably in 0.2 to 15 seconds.

[0108] The reactor can be, in particular, an autoclave reactor. However, the high-pressure polymerization system may also include multiple reactors, such as a combination of an autoclave reactor and a tubular reactor. Preferably, at least one autoclave reactor, or even only an autoclave reactor, includes at least one release line with rupture discs. Preferably, at least two release lines are provided, which are radially connected to the autoclave reactor on opposite sides.

[0109] Once the rupture disc ruptures, it can be replaced. If the rupture disc is located on a replaceable module at the end forming the corresponding release line, the maintenance workload for replacing the rupture disc can be greatly reduced. This module can be detached from the rest of the release line and replaced by another module with a intact rupture disc, allowing for convenient and quick replacement.

[0110] One or more release lines may extend into the radial opening of the reactor. One or more release lines may extend into the radial opening such that the rupture discs, preferably forming the ends of the release lines, are arranged flush with the inner surface of the reactor wall.

[0111] Alternatively, one or more release lines may protrude radially into the reactor volume. In this embodiment, one or more release lines may additionally serve as anchoring elements for securing components inside the reactor, such as a stirrer coaxially mounted within the reactor. The stirrer may be directly attached to one or more release lines, or it may be secured via a fixing element.

[0112] A first connection line can be attached to the reactor outlet to allow fluid communication between the reactor and a post-reactor cooler or separation vessel (preferably a post-reactor cooler). A pressure control valve can be provided, adapted and arranged to control the fluid communication between the continuously operating polymerization reactor and the post-reactor cooler or separation vessel.

[0113] Furthermore, the first connecting line may include at least one, preferably two, emergency valves adapted to open and close fluid communication between the continuously operating polymerization reactor and the reactor venting vessel via the first connecting line. If two emergency valves are provided, it is preferred that one emergency valve is installed upstream of the pressure control valve and the other downstream of the pressure control valve. The emergency valves can serve as a primary safety measure to depressurize the reactor at a first predetermined pressure threshold. However, if the pressure in the reactor continues to rise or the emergency valves malfunction, a rupture disc can serve as a fail-safe device to ensure that the pressure inside the reactor does not reach the design pressure.

[0114] In a preferred embodiment, the reactor vent container may have a substantially circular design above a main portion P having a length L, a diameter D, and an L / D ratio in the range of 1.75 to 10.0, preferably in the range of 2.0 to 6.0, and particularly in the range of 2.0 to 4.0, and the reactor vent container contains an aqueous quenching medium.

[0115] The reactor venting system also includes:

[0116] b4) Nitrogen coverage system and / or

[0117] b5) Fill level control system.

[0118] The reactor venting vessel b1) may also include a ventilation riser serving as a gas outlet for removing gaseous components that have been separated from the aqueous polymer slurry. This ventilation riser is characterized by including a contraction section, such as a throttle valve. In a preferred embodiment of this disclosure, the ventilation riser is a vertical pipe with an inner diameter of 0.4 m to 1.4 m, more preferably 0.5 m to 1.1 m, and particularly 0.7 m to 0.9 m. The contraction section of the ventilation riser preferably has a smaller inner diameter than the vertical pipe, such that the cross-sectional area of ​​the opening at the contraction section is 10% to 60% of the cross-sectional area of ​​the opening of the vertical pipe, more preferably 15% to 50%, and particularly 15% to 50%. In a preferred embodiment of this disclosure, the upper opening of the ventilation riser is 20 m to 80 m above the ground plane, more preferably 30 m to 60 m above the ground plane, and particularly 40 m to 50 m above the ground plane.

[0119] Preferably, the reactor vent container is covered with nitrogen, although it is open to the atmosphere.

[0120] In a preferred embodiment of this disclosure, the reactor venting system further includes:

[0121] b6) A reactor venting and unloading vessel, which is arranged and adapted to be in fluid communication with the reactor venting vessel, and

[0122] b7) At least one discharge valve in the fluid communication between the reactor vent container and the reactor vent discharge container, and adapted and arranged to open or close the fluid communication between the reactor vent container and the reactor vent discharge container.

[0123] The reactor vent container is installed above the reactor venting and unloading container.

[0124] This disclosure also provides a method for polymerizing ethylene and optionally one or more comonomers in a high-pressure polymerization system according to any one of the above embodiments to obtain an ethylene-based polymer.

[0125] The method includes the following steps:

[0126] A) Monitor the occurrence of disturbances in the high-pressure polymerization system, and

[0127] B) If the predetermined pressure threshold is exceeded, the contents of the reactor will be automatically released into the reactor vent container;

[0128] C) Contacting the contents of the vented container of the reactor with an aqueous quenching medium to obtain an aqueous polymer slurry; and

[0129] D) Separate the aqueous polymer slurry and the gaseous component.

[0130] In a preferred embodiment, the method further includes the step of: between steps A) and B), opening at least one emergency valve in the event of a disturbance to allow the contents of the polymerization system, comprising polymer and gaseous components, to expand via a first connecting line into the reactor vent container. Thus, the occurrence of disturbances in the high-pressure polymerization system is monitored. In the event of a disturbance, at least one emergency valve is opened, and the contents of the polymerization system, comprising polymer and gaseous components, are allowed to expand into the reactor vent container. In this way, the high-pressure polymerization is interrupted in a controlled manner. Therefore, in the context of this disclosure, a disturbance is any deviation from normal polymerization conditions that is considered significant enough to necessitate termination of the polymerization. Monitoring of the high-pressure polymerization system is performed by measuring various parameters relating to the conditions of the high-pressure polymerization system. These parameters include pressure and temperature at various locations within the polymerization system, container fill level, valve positions, hydrocarbon concentration around the high-pressure polymerization system, and vibrations within the polymerization system. If any of these parameters deviates significantly from a normal value, for example, more than 10% from a typical measurement, a disturbance is established, and at least one emergency valve is opened.

[0131] In a preferred embodiment of this disclosure, the method further includes:

[0132] E) Transfer the aqueous polymer slurry to the reactor venting and unloading container by opening at least one discharge valve.

[0133] In some embodiments, when a disturbance or temporary deviation from the occurrence of a disturbance occurs, particularly with a delay in the range of 2 to 30 seconds, and more particularly in the range of 4 to 16 seconds, steam, preferably medium-pressure steam, is injected, particularly via a venting riser, into the reactor venting vessel.

[0134] In some embodiments, when a disturbance occurs, the injection of steam into the reactor venting vessel is suspended, particularly via the venting riser, after about 120 to 300 seconds, preferably after about 140 to 220 seconds.

[0135] In some embodiments of this disclosure, after the first emergency valve or any combination of previously opened emergency valves has been closed, at least one drain valve is opened to transfer the aqueous polymer slurry to the reactor venting and unloading vessel. In suitable embodiments of this disclosure, at least one drain valve is remotely operated or operable.

[0136] In another embodiment, after the first emergency valve or any combination of previously opened emergency valves has been closed, at least one discharge valve is opened to transfer the aqueous polymer slurry to the reactor venting and dumping container.

[0137] In a preferred embodiment of this disclosure, after a disturbance has occurred and the reactor vent container has been emptied, polymerization is restarted, for example, by transferring the aqueous polymer slurry into the reactor vent dump container.

[0138] In a preferred embodiment of this disclosure, the first emergency valve or any combination of previously opened emergency valves will close again as long as the fluid communication system, or the fluid communication system and the third and / or fourth connecting lines, are under positive pressure.

[0139] In a preferred embodiment of this disclosure, the reactor vent container and the reactor vent dump container are housed within a protective enclosure, commonly referred to as a “reactor chamber,” and / or a vent separator or combination of vent separator elements and / or a circulation pump or multiple circulation pumps are located outside the protective enclosure.

[0140] In most cases, the aqueous quenching medium is water. In some cases, such as for the production of ethylene copolymers, the aqueous quenching medium, in addition to water, also includes at least one polymerization inhibitor, such as hydroquinone or a pH buffer. Buffers include, for example, phosphate buffers, which are obtained by mixing disodium hydrogen phosphate and sodium hydroxide.

[0141] Using the method of this disclosure, the contents of the polymerization system are expanded into a reactor vent container and brought into contact with an aqueous quenching system. In this way, the pressure in the continuous high-pressure polymerization system can be rapidly reduced, for example, from a predetermined pressure threshold to 0.1 MPa within one minute or even less. As the gaseous components are released from this container, the water / polymer mixture can be removed from the reactor vent dump container. By utilizing the specific total area of ​​the rupture discs installed per reactor volume, it can be ensured that the high-pressure polymerization system can depressurize from the predetermined pressure threshold to 100 MPa in less than 10 seconds, preferably less than 8 seconds, more preferably within 0.1 to 5 seconds. In particular, the system can be designed to depressurize from the predetermined pressure threshold to approximately 30 MPa within 0.1 to 30 seconds, preferably within 0.2 to 15 seconds.

[0142] Other features and advantages of this disclosure will become apparent from the following description, wherein the disclosure is not limited by way of example and exemplary embodiments thereof are explained with reference to schematic diagrams.

[0143] Figure 1A schematic apparatus structure of a polymerization apparatus according to exemplary embodiments of the present disclosure is shown. A process gas comprising a mixture of olefinic unsaturated monomers or a mixture of olefinic unsaturated monomers with one or more copolymers is compressed in a series of compressors having a booster compressor (100a), a main compressor (100b), and a super compressor (100c). Fresh olefinic unsaturated monomers, chain transfer agents (CTA), and / or comonomers may be introduced via feed lines (102) and (103), respectively. The compressed process gas is conveyed to a cooler system (104), optionally preheated in a start-up heater (105), and introduced into the polymerization reactor (108) via a feed line (116). A portion of the process gas is premixed with a polymerization initiator supplied by pumps (106a) and (106b). In this exemplary embodiment, the polymerization reactor (108) is in the form of a continuously operating autoclave reactor equipped with a motor (109) and a stirrer baffle (111) that divides the reactor into different reaction zones. The reactor (108) also includes a mixing element (110) mounted on a stirrer shaft (117) for mixing the contents of the reactor (108).

[0144] The reaction mixture can exit the polymerization reactor (108) via a connecting line (120) (equipped with a pressure control valve (118)) and pass through a post-reactor cooler (112). Thereafter, the resulting polymer is separated from unreacted ethylene and other low molecular weight compounds (monomers, oligomers, polymers, additives, solvents, etc.) by a first separation vessel (113a) and a second separation vessel (113b), discharged, and granulated via an extruder and a granulator (114).

[0145] The ethylene and comonomers, already separated in the first separation vessel (113a), are fed back to the reactor (108) via a high-pressure loop (115b). In the high-pressure loop (115b), the gaseous substances separated from the reaction mixture are first purified in at least one stage to remove other components, and then fed into the monomer stream between the main compressor (101b) and the super compressor (101c). The high-pressure loop (115b) can also separate the solvent from the wax.

[0146] The ethylene that has been separated in the second separation vessel (113b) is processed in a low-pressure loop (115a), which, among other things, contains the bulk of the polymerized very low molecular weight products (oligomers) and solvent. The low-pressure loop includes multiple separators, each of which is connected by a heat exchanger. Figure 1Two purification stages, consisting of a heat exchanger and a separator, are shown. However, only one purification stage may be used, or preferably more than two purification stages. The low-pressure circuit (115a) typically separates oil, solvent, and wax. The treated ethylene is first compressed in a booster compressor (101a) and then returned to the main compressor (101b).

[0147] Under certain temperature and pressure conditions, ethylene can rapidly decompose explosively, yielding soot, methane, and hydrogen. This is accompanied by a dramatic increase in pressure and temperature. Decomposition temperatures can become excessively high (>1000°C), posing a considerable potential risk to the operational safety of the production facility. For example, temperatures reached during such decomposition events can damage reactor tubes, potentially causing austenitization of the tube metal. At austenitizing temperatures, if the material is rapidly cooled, martensite forms in the reactor tubes. Martensite is the hardest and most brittle of the various microstructures found in carbon steel.

[0148] To rapidly depressurize the reactor (108), for example in the case of decomposition, one or more release lines (122) connect the polymerization reactor (108) to a reactor vent container and include a release line outlet for expanding the contents of the high-pressure polymerization system, comprising polymer and gaseous components, into the reactor vent container, wherein the release line outlet is located above the maximum level of the aqueous quenching medium. Each release line (122) is equipped with a rupture disc (124) that automatically allows the contents of the high-pressure polymerization system to enter the reactor vent container through the corresponding release line (122) if a predetermined pressure threshold is exceeded in the reactor.

[0149] Furthermore, the connecting line (120) may be equipped with an emergency valve (126) adapted to open or close the fluid communication between the polymerization reactor (108) and the reactor venting vessel via an arm (128) branching off from the connecting line (120). Preferably, two emergency valves are provided, one of which (126) is located on the connecting line (120) between the pressure control valve (118) and the outlet of the reactor (108). The other emergency valve (126) may be located on the connecting line (120) between the pressure control valve (118) and the after-reactor cooler (112). The emergency valves may serve as a primary safety measure to depressurize the reactor at a first predetermined pressure threshold. However, if the pressure and / or temperature in the reactor continues to rise or the emergency valves fail, a rupture disc (124) may serve as a fail-safe device to ensure that the pressure inside the reactor does not reach the design pressure. In addition, one or more emergency valves may be provided upstream of the reactor (108) and downstream of the super compressor (101c), the one or more emergency valves being adapted to open and close the fluid communication between the compressor and the venting container via an arm (128) branching off from the pipeline between the super compressor (101c) and the reactor (108).

[0150] exist Figure 1 In the illustrated embodiment, the rupture disc (124) is positioned at the end of the release line (122). The release line (122) protrudes into the wall of the reactor (108) such that the front end face of the rupture disc (124) is substantially flush with the inner surface of the reactor wall. This prevents the accumulation of polymer material or fine powder around the release line.

[0151] Figure 2 A schematic diagram of the apparatus structure in which the polymerization reactor (108) is connected to the reactor venting system (201) via release lines (122) is shown. In this embodiment, each release line (122) has a front end that extends radially into the reactor. As in Figure 2 As can be seen, at least two release lines (122) can be provided, which are arranged opposite to each other relative to the vertical axis of the reactor (108). The front end can be formed by a replaceable module (202) including a rupture disc (124). Therefore, once the rupture disc (124) ruptures, it is not necessary to replace the entire release line (122), but it is sufficient to replace the module (202) with another module (202) having an intact rupture disc (124).

[0152] The release line (122) can extend into the volume of the reactor (108), and thus the release line (122) can also be used as an anchor for securing the agitator shaft (117) inside the reactor. For this purpose, an attachment part (211) can be provided for attaching the agitator shaft (117) to the release line (122).

[0153] Each release line (122) can be mounted to the mounting collar (204) via a flange (206). Preferably, each release line (122) is divided into two arms (208), each arm being attached to the reactor venting vessel (210) at a circumferentially spaced position.

[0154] The release line (122) is adapted to depressurize the reactor (108) if a predetermined pressure threshold is exceeded. Once the predetermined pressure threshold is exceeded, the rupture disc breaks, thereby opening a passage through the release line (122) into the reactor vent container (210). Each arm includes a fitting (212) that connects the corresponding arm to the reactor vent container, forming a corresponding release line outlet (214).

[0155] Figure 3 A possible device structure of the reactor venting system (201) of this disclosure is schematically shown, comprising a reactor venting vessel (210), vent line outlets (214), and a ventilation riser (301). Only two vent line outlets (214) are shown in this schematic diagram. However, it should be understood that the number of vent line outlets (214) may be more than two, such as... Figure 2 As shown. Preferably, the number of release line outlets (214) is even, wherein the release line outlets are distributed along the circumference of the reactor vent container. The reactor vent container (210) has a cylindrical portion of length L, which is referred to as the "main portion P" (302). The main portion P (302) has a diameter D. Figure 3 In the schematic diagram, the main portion P (302) has an L / D ratio of approximately 2.1. Above the main portion P (302), the reactor vent container (210) includes a conical cap-shaped portion, the central portion of which is equipped with a lower part of a ventilation riser (301). The lower part (304) of the reactor vent container (210) has a conical shape and includes an aqueous quenching medium (306) in use. Figure 3 In the depicted embodiment, the surface (308) of the aqueous quenching medium (306) is located below the overflow valve (310). The aqueous quenching medium (306) can be added to the reactor vent container (210) via the water inlet valve (312). Nitrogen gas for covering the reactor vent container can be introduced through the nitrogen inlet (314). The release line outlets (214) each include fittings (212) and (212), through which hot gases and hot polymers enter the reactor vent container (210), for example, in the event of disturbances in the polymerization process at the polymerization reactor. The fittings (212) are oriented in such a way that... Figure 3In the embodiments shown, in their respective cases, the angle of inclination (β) between the central axis (316) of the corresponding joint (212) and the horizontal plane passing through the main portion P (302) of the reactor venting container (210) is approximately 12°, wherein the central axis (316) intersects the horizontal circumference of the main portion P (302). Furthermore, in Figure 3 In an embodiment of the reactor venting system (201), the fitting (212) is arranged substantially tangentially to the horizontal circumference of the main portion P (302). At the bottom of the conical lower portion (304) of the reactor venting container (210), there is an outlet (318) that can be remotely opened and closed, and through which precipitated polymer can be removed.

[0156] Surprisingly, it was found that under disturbed or even emergency conditions, such as when reactor pressure and / or reactor temperature exceed safety thresholds, the hot gas stream and hot polymerizing material in the polymerization reactor can be effectively quenched and cooled. Therefore, using the high-pressure polymerization system according to this disclosure, the momentum of the gas and material streams is significantly reduced in a controlled manner, resulting in excellent quenching of the polymer / gas mixture in the reactor venting vessel without releasing a significant amount of polymer material or even substantially no amount of polymer material released into the atmosphere via the venting riser. The polymer material can be effectively and completely separated from the quenched reactor contents, including both hot ethylene and hot polymer, in the reactor venting vessel, allowing substantially all solids to be retained.

[0157] Using the method and high-pressure polymerization system disclosed herein, if a predetermined pressure threshold is exceeded, the reactor can be automatically depressurized by automatically rupturing the rupture disc in any disturbance or emergency. In other words, polymerization can be safely stopped not only in emergencies such as fire, explosion, earthquake, or polyethylene decomposition, but also if a deviation from standard operating conditions (i.e., a disturbance) is detected, for example, exceeding a predetermined threshold.

[0158] Other features, advantages, and embodiments of the subject matter disclosed herein will become apparent to those skilled in the art upon reading the foregoing disclosure. In this regard, while specific embodiments of the subject matter of this disclosure have been described in considerable detail, variations and modifications of these embodiments may be made without departing from the spirit and scope of the disclosure as described and claimed.

[0159] Figure Labels

[0160] 1 High-pressure polymerization system

[0161] 101a, 101b, 101c booster compressors, main compressors, and secondary compressors

[0162] 102 feed line

[0163] 103 feed line

[0164] 104 Cooler System

[0165] 105 preheater

[0166] 106a and 106b pumps

[0167] 108 polymerization reactor

[0168] 109 motor

[0169] 110 hybrid element

[0170] 111 Mixer Baffle

[0171] 112 After-reactor cooler

[0172] 113a, 113b First separation container and second separation container

[0173] 114 Extruder and Granulator

[0174] 115a, 115b low-voltage circuit and high-voltage circuit

[0175] 116 feed line

[0176] 117 Mixer Shaft

[0177] 118 pressure control valve

[0178] 120 connecting pipeline

[0179] 122 release pipeline

[0180] 124 shrapnel

[0181] 126 Emergency Valve

[0182] 128 arms

[0183] 201 Reactor Venting System

[0184] 202 Replaceable Module

[0185] 204 installation collar

[0186] 206 flange

[0187] 208 arms

[0188] 210 vent container

[0189] 211 Attachment

[0190] 212 joint

[0191] 214 Release Pipeline Outlet

[0192] 301 ventilation riser

[0193] 302 main parts

[0194] 304 lower part

[0195] 306 Water-based quenching medium

[0196] 308 surface

[0197] 310 relief valve

[0198] 312 Water Inlet Valve

[0199] 314 Nitrogen Inlet Valve

[0200] 316 central axis

Claims

1. A high-pressure polymerization system (1), the high-pressure polymerization system comprising: a) A continuously operating polymerization reactor (108), the continuously operating polymerization reactor having a reactor inlet and a reactor outlet, and b) A reactor venting system (201), the reactor venting system being adapted and arranged in fluid communication with the polymerization reactor (108), the reactor venting system (201) comprising: b1) Reactor venting container (210), the reactor venting container containing an aqueous quenching medium (306). b2) One or more release lines (122) connecting the polymerization reactor (108) to the reactor vent container (210) and including a release line outlet (214) for expanding the contents of the high-pressure polymerization system (1), comprising polymer and gaseous components, into the reactor vent container (210), wherein the release line outlet (214) is located above the maximum level of the aqueous quenching medium (306), and The one or more release lines (122) are equipped with rupture discs (124) that automatically allow the contents of the high-pressure polymerization system (1) to enter the reactor vent container (210) through the one or more release lines (122) if a predetermined pressure threshold is exceeded in the reactor.

2. The high-pressure polymerization system according to claim 1, wherein the high-pressure polymerization system reduces the pressure from the predetermined pressure threshold to 100 MPa in less than 10 seconds, preferably in less than 5 seconds.

3. The high-pressure polymerization system according to claim 1 or 2, wherein the predetermined pressure threshold is approximately 10 to 700 bar less than the design pressure of the reactor, preferably 100 to 600 bar less, and more preferably 200 to 500 bar less.

4. The high-pressure polymerization system according to any one of claims 1 to 3, wherein the total area of ​​the rupture discs installed per reactor volume can be about 0.003 to 0.050 m² / m³, preferably 0.004 to 0.025 m² / m³, and more preferably 0.005 to 0.017 m² / m³.

5. The high-pressure polymerization system according to any one of claims 1 to 4, wherein the number of rupture discs is about 1 to 9, preferably 1 to 6, and more preferably 2 to 4.

6. The high-pressure polymerization system according to any one of claims 1 to 5, wherein the reactor is an autoclave reactor or a combination of an autoclave reactor and a tubular reactor.

7. The high-pressure polymerization system according to any one of claims 1 to 6, wherein the rupture disc is disposed on a replaceable module forming the end of one or more release lines.

8. The high-pressure polymerization system according to any one of claims 1 to 7, wherein one or more release lines extend into the radial opening of the reactor.

9. The high-pressure polymerization system according to claim 8, wherein, The rupture disc is disposed inside the reactor. The rupture disc can, for example, close the radial opening of the reactor and be flush with the inner reactor wall. Specifically, the rupture disc can be disposed at the end of the release line that connects to the reactor.

10. The high-pressure polymerization system according to claim 8 or 9, wherein, A stirrer is provided, which is coaxially mounted in the reactor, wherein the stirrer is fixed to one or more release lines, or an assembly of one or more release lines protrudes into the reactor.

11. The high-pressure polymerization system according to any one of claims 1 to 10, wherein the polymerization system further comprises a connecting line for connecting the polymerization reactor to a post-reactor cooler, and wherein the connecting line is provided with one or more first emergency valves adapted to open and close fluid communication between the polymerization reactor and the reactor venting system.

12. The high-pressure polymerization system according to any one of claims 1 to 11, wherein the release line connecting the polymerization reactor to the reactor venting vessel is heated to a temperature of 160°C to 240°C.

13. The high-pressure polymerization system according to any one of claims 1 to 11, wherein one or more release lines are divided into at least two arms, the at least two arms being connected to the reactor venting vessel at different locations.

14. A method for polymerizing ethylene and optionally one or more comonomers in a high-pressure polymerization system as defined above to obtain an ethylene-based polymer, the method comprising: A) Monitor the occurrence of disturbances in the high-pressure polymerization system, and B) If the predetermined pressure threshold is exceeded, the contents of the reactor will be automatically released into the reactor vent container; C) Contacting the contents of the vented reactor vessel with an aqueous quenching medium to obtain an aqueous polymer slurry; and D) Separate the aqueous polymer slurry and the gaseous components.

15. The method of claim 14, wherein the method further comprises: E) Transfer the aqueous polymer slurry to the reactor venting and unloading container by opening at least one discharge valve.

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