A continuous ethylene selective oligomerization device and method

Abstract

The present invention discloses a continuous ethylene selective polymerization device and method. The device and method feed ethylene through a feed nozzle arranged on the wall of the reactor and regularly wash the polymer attachments on the inner surface of the reactor with a high-pressure solvent jet; the reaction liquid after quenching is subjected to two-stage sedimentation, and the upper clear liquid directly enters the subsequent distillation separation unit, thereby realizing continuous operation; the slurry with high insoluble content in the lower layer after precipitation and concentration is discharged from the system in a centralized manner, and then solid-liquid separation is performed, thereby avoiding the problems of easy filter blockage, ineffective backwashing, frequent switching, difficult cleaning, and influence on continuous operation when filtering directly in a continuous and high-pressure system. The present invention provides a solution to the insoluble ethylene polymers produced by side reactions during continuous ethylene selective polymerization, thereby realizing long-term continuous and stable operation of the device.

Description

Technical Field

[0001] The invention relates to the technical field of ethylene selective oligomerization reaction, in particular to a continuous ethylene selective oligomerization reaction device and a reaction process thereof, and in particular to a continuous ethylene selective oligomerization device and method. Background Art

[0002] Linear α-olefins are an important class of chemical raw materials and intermediates, and have extremely important applications in high-performance polyolefins, high-end lubricants, surfactants and other fields. In recent years, with the rapid development of high-end PE, POE and other materials, the market demand for linear α-olefins, especially 1-hexene and 1-octene, has increased significantly. Compared with traditional processes, the selective polymerization of ethylene to prepare high-grade α-olefins such as 1-hexene and 1-octene has become a research hotspot due to its advantages such as high catalyst activity and high product selectivity. At present, a large number of high-efficiency catalysts have been developed and reported in the field of catalysts, but the polymerization process is the difficulty and bottleneck that restricts its industrial implementation.

[0003] In the selective polymerization of ethylene, no matter which efficient catalytic system is selected, side reactions are difficult to avoid, especially in continuous devices. Affected by factors such as material mass transfer, reuse, residence time, and heat removal, side reactions increase, and different forms of ethylene polymers are produced. Among them, a small part of the polymer adheres to the inner surface of the reactor and grows to form a wax layer as the reaction proceeds, entangles into a ball on the stirring paddle, and deposits in the low-flow pipeline to form a blockage, which seriously affects the heat and mass transfer of the reaction device; most of the polymer is suspended in the reaction solution, and runs backward with the reaction solution, thereby affecting subsequent operations, especially the distillation separation unit, and ultimately leading to unstable operation of the continuous device, short cycle, and frequent maintenance. As in the prior art, CN108026200B discloses minimizing the local low temperature zone and the ethylene high concentration zone by temperature process control to reduce scaling and blockage caused by side reactions. CN113511949A discloses that after the loop reactor is cut out of the reaction system, the reactor temperature is increased to remove the solid polymer in the reactor tube. CN110639459A discloses that ethylene is sprayed into the reaction liquid through gas distribution holes at different positions on the coil in the reactor, thereby improving mass transfer, making the ethylene concentration distribution in the reaction liquid more uniform, avoiding excessive generation of by-product oligomers due to excessive local ethylene concentration, and at the same time achieving flushing of the heat exchange tube surface to slow down the adhesion of oligomers to the equipment.

[0004] However, the above technical solutions all try to reduce side reactions by controlling the temperature and local ethylene concentration, and eliminate the attachments on the reactor through heating, melting, online flushing and other operations. However, they do not provide a solution for treating the polymer suspension in the reaction liquid without affecting the continuous operation of the device.

[0005] Therefore, how to find a more suitable way to solve the above-mentioned problems in the ethylene selective polymerization reaction process while ensuring the continuous and long-term operation of the device has become one of the urgent issues to be solved by many front-line researchers in the industry. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a continuous ethylene selective oligomerization reaction device and a reaction process thereof. The device and method provided by the present invention can discharge the insoluble polymer produced by ethylene selective oligomerization from the device without affecting the continuous and stable operation of the device, truly realizing the long-term operation of the device, and has important industrial application value.

[0007] The present invention provides a continuous ethylene selective oligomerization reaction device, comprising:

[0008] Reactor;

[0009] A quenching kettle connected to the reactor;

[0010] A first settling tank connected to the quenching kettle;

[0011] a second settling tank connected to the first settling tank;

[0012] a clear liquid buffer tank connected to the second settling tank;

[0013] A gas-liquid separation tank connected to the clear liquid buffer tank.

[0014] Preferably, the reactor is connected with an ethylene feed pipeline, a solvent feed pipeline and a catalyst feed pipeline;

[0015] One or more feed nozzles are arranged on the wall of the reactor;

[0016] The feed nozzle is connected to an ethylene feed pipeline and / or a solvent feed pipeline;

[0017] The feed nozzle is arranged at a distance of 15% and / or 45% of the kettle volume from the bottom of the kettle;

[0018] A solvent feeding pipeline which is not connected to the nozzle is also arranged on the top of the reactor.

[0019] Preferably, the reaction kettle is connected to the quenching kettle via a discharge pipeline arranged at the bottom of the kettle;

[0020] The quenching kettle is connected with a quenching agent feeding pipeline;

[0021] The quenching kettle is connected to the first settling tank via a discharge pipeline arranged at the bottom of the kettle;

[0022] The first settling tank is provided with a guide plate and a partition;

[0023] The partition is specifically arranged along the height direction of the settling tank;

[0024] The partition is connected to the tank top and is spaced apart from the tank bottom.

[0025] Preferably, one or more sampling ports are also provided in the middle and lower part of the first settling tank;

[0026] The first settling tank is connected to the second settling tank via a discharge pipeline arranged at the upper part of the tank body;

[0027] The second settling tank is provided with a guide plate and a partition;

[0028] The partition is specifically arranged along the height direction of the settling tank;

[0029] The partition is connected to the tank top and is spaced apart from the tank bottom;

[0030] One or more sampling ports are also provided in the middle and lower part of the first settling tank.

[0031] Preferably, the device further comprises a second gas-liquid separation tank and a filter;

[0032] The second gas-liquid separation tank is respectively connected to the discharge pipelines of the sedimentation materials at the bottom of the first sedimentation tank and the second sedimentation tank;

[0033] The solid-liquid mixture outlet of the second gas-liquid separation tank is connected to the filter;

[0034] The gas phase outlet of the second gas-liquid separation tank is connected to the ethylene recycling unit;

[0035] The liquid phase outlet of the filter is connected to a separation unit;

[0036] The filter is also provided with an ethylene polymer solid phase outlet.

[0037] Preferably, the second sedimentation tank is connected to the clear liquid buffer tank via a discharge pipeline arranged at the upper part of the tank body;

[0038] The clear liquid buffer tank is connected to the gas-liquid separation tank via a discharge pipeline arranged at the bottom of the tank body;

[0039] The gas phase outlet of the gas-liquid separation tank is connected to the ethylene recycling unit;

[0040] The liquid phase outlet of the gas-liquid separation tank is connected to the separation unit.

[0041] The present invention also provides a continuous ethylene selective oligomerization process, comprising the following steps:

[0042] 1) continuously feeding the solvent, catalyst and ethylene into the reactor to carry out the selective polymerization of ethylene, and conveying the reaction liquid to the quenching kettle to maintain the liquid level of the reactor;

[0043] 2) After continuously feeding the quenching agent into the quenching kettle to quench the activity of the catalyst, the quenched reaction liquid is then transported to the first settling tank to maintain the liquid level of the quenching kettle;

[0044] 3) The quenched reaction liquid is guided by a guide plate in the first settling tank to slow down the flow rate, and is precipitated with the assistance of a baffle. The insoluble polymer is deposited at the bottom of the tank, and the upper liquid enters the second settling tank through an overflow pipeline. After secondary sedimentation, the upper clear liquid enters the clear liquid buffer tank through an overflow pipeline;

[0045] 4) The clear liquid in the clear liquid buffer tank is transported to the gas-liquid separation tank to maintain the liquid level of the clear liquid buffer tank;

[0046] 5) After the clear liquid in the gas-liquid separation tank is separated into gas and liquid, the gas is recycled and the liquid enters the subsequent distillation separation unit.

[0047] Preferably, the pressure in the reactor is 4-6 MPa;

[0048] The temperature in the reactor is 55-60°C;

[0049] The liquid level control range of the reactor is 20% to 80% of the reactor volume;

[0050] The amount of reaction liquid transported to the rear path by the reactor each time is 1% to 20% of the reactor volume.

[0051] Preferably, the liquid level control range of the quenching kettle is 20% to 80% of the kettle volume;

[0052] The amount of reaction liquid transported to the back path by the quenching kettle each time is 1% to 20% of the kettle volume;

[0053] The liquid level control range of the clear liquid buffer tank is 20% to 80% of the kettle volume;

[0054] The amount of reaction liquid transported to the rear path by the clear liquid buffer tank each time is 1% to 20% of the kettle volume.

[0055] Preferably, sampling is performed through the sampling port of the first settling tank and / or the second settling tank to monitor the settling of insoluble matter. When the insoluble matter that has aggregated and settled is found during sampling, the slurry after settling is discharged into the second gas-liquid separation tank through the bottom valve at the bottom of the settling tank and the discharge amount is determined according to the position of the settling tank where the sampling port is located and the actual liquid level change in the settling tank;

[0056] After the precipitated slurry is separated into gas and liquid, the gas is incorporated into the recycling system, the slurry liquid enters the filter to filter out the insoluble ethylene polymer, and the filtrate enters the separation unit with the clear liquid.

[0057] The present invention provides a continuous ethylene selective polymerization reaction device, comprising a reactor; a quenching kettle connected to the reactor; a first settling tank connected to the quenching kettle; a second settling tank connected to the first settling tank; a clear liquid buffer tank connected to the second settling tank; and a gas-liquid separation tank connected to the clear liquid buffer tank. Compared with the prior art, the present invention studies the problems existing in the existing improved process. Although there are also technical solutions that disclose that liquid ethylene and solvent are sprayed into the reactor through a distributor or a nozzle to flush the feed distribution system, agitator and other parts, reduce equipment adhesion and blockage, and perform online cleaning of parts in the reactor that are prone to waxing, there is still a problem that insoluble matter is difficult to remove from the system, resulting in unstable operation of the subsequent process and affecting the continuous operation of the overall process.

[0058] Based on this, the present invention specially designs a continuous ethylene selective oligomerization device and method, the core of which is the cleaning and discharge of insolubles in the entire reaction system. The present invention eliminates the influence of insolubles by discharging insoluble ethylene polymers produced by side reactions without affecting the continuous operation of the ethylene selective oligomerization device, thereby achieving long-term continuous and stable operation of the device.

[0059] The present invention performs secondary sedimentation on the polymerization reaction liquid containing insoluble polymers, discharges the settled insolubles from the continuous system in a centralized manner, and then performs conventional filtration. The method avoids the drawbacks of easy clogging of the filter, ineffective backwashing, frequent switching, and difficult cleaning when the insoluble polymers are filtered online in a continuous high-pressure system, does not affect the continuous operation of the device, and reduces the frequency and intensity of the filtering operation, thereby achieving the discharge of the insoluble polymers and eliminating the harm to the device and the subsequent distillation and separation unit.

[0060] Moreover, the guide plate in the settling tank of the present invention can guide the reaction liquid to slowly merge into the settled reaction liquid, reducing impact and disturbance; the partition in the settling tank plays an auxiliary sedimentation role; the overflow pipeline also slows down the flow rate of the supernatant, which is beneficial to the sedimentation of the insoluble polymer.

[0061] At the same time, the four sampling ports provided at different volumes on the side of the sedimentation tank of the present invention can directly take out slurry samples at corresponding depths of the sedimentation tank to monitor the sedimentation state of the insoluble polymer, and can adjust the sedimentation time and the amount of liquid discharged each time according to the continuous reaction situation, thereby improving the response flexibility.

[0062] Furthermore, the reactor of the present invention is provided with four feed nozzles at 15% and 45% of the volume, respectively, which are opposite to each other. When feeding continuously, the nozzles serve as the feed ports of ethylene, so that ethylene directly enters the reaction liquid, thereby improving the mass transfer effect. When cleaning the attachments in the reactor, the solvent line can be switched to flush with a high-pressure solvent jet, with four nozzles at each horizontal position, and a spray angle of 45°, covering the inner surface of the space occupied by the liquid phase when the reactor is operating normally. In addition, the present invention also automatically controls the equipment liquid level and the amount of each delivery through a bottom valve interlocked with the corresponding equipment liquid level, thereby realizing continuous material delivery, with a high degree of automation.

[0063] Experimental results show that the device and method provided by the present invention can meet the requirements of long-term operation of continuous ethylene polymerization reaction. The device can operate continuously and stably for more than 90 days. 99.3% of insoluble polymer solids produced by side reactions are discharged from the continuous system. No blockage occurs in various equipment and pipelines. The reaction activity and selectivity of the catalyst used meet the predetermined standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 The present invention provides a schematic diagram of the process flow of a continuous ethylene selective oligomerization device. DETAILED DESCRIPTION

[0065] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0066] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0067] The raw materials used in the present invention have no particular limitation on their purity. The present invention preferably uses industrial pure raw materials or raw materials with a purity conventional in the field of preparing α-olefins by ethylene selective oligomerization.

[0068] All noun expressions and abbreviations in the present invention are conventional noun expressions and abbreviations in the field. Each noun expression and abbreviation is clear and unambiguous in its relevant application field. Those skilled in the art can clearly, accurately and uniquely understand them based on the noun expressions and abbreviations.

[0069] The present invention provides a continuous ethylene selective oligomerization reaction device, comprising:

[0070] Reactor;

[0071] A quenching kettle connected to the reactor;

[0072] A first settling tank connected to the quenching kettle;

[0073] a second settling tank connected to the first settling tank;

[0074] a clear liquid buffer tank connected to the second settling tank;

[0075] A gas-liquid separation tank connected to the clear liquid buffer tank.

[0076] In the present invention, the reactor is preferably connected with an ethylene feed pipeline, a solvent feed pipeline and a catalyst feed pipeline.

[0077] In the present invention, one or more feed nozzles are preferably provided on the wall of the reactor.

[0078] In the present invention, the feed nozzle is preferably connected to an ethylene feed pipeline and / or a solvent feed pipeline, and more preferably connected to an ethylene feed pipeline and a solvent feed pipeline.

[0079] In the present invention, the feed nozzle is preferably arranged at a distance of 15% and / or 45% of the kettle volume from the kettle bottom, more preferably at 15% and 45% of the kettle volume.

[0080] In the present invention, the top of the reactor is preferably further provided with a solvent feeding pipeline which is not connected to the nozzle.

[0081] In the present invention, the reaction kettle is preferably connected to the quenching kettle via a discharge pipeline arranged at the bottom of the kettle.

[0082] In the present invention, the quenching kettle is preferably connected with a quenching agent feeding pipeline.

[0083] In the present invention, the quenching kettle is preferably connected to the first settling tank via a discharge pipeline arranged at the bottom of the kettle.

[0084] In the present invention, a guide plate and a partition are preferably provided in the first settling tank.

[0085] In the present invention, the partition is preferably arranged along the height direction of the settling tank.

[0086] In the present invention, the partition is preferably connected to the tank top and spaced apart from the tank bottom.

[0087] In the present invention, one or more sampling ports are preferably provided in the middle and lower part of the first settling tank.

[0088] In the present invention, the first sedimentation tank is preferably connected to the second sedimentation tank via a discharge pipeline disposed at the upper portion of the tank body.

[0089] In the present invention, a guide plate and a partition are preferably provided in the second settling tank.

[0090] In the present invention, the partition is preferably arranged along the height direction of the settling tank.

[0091] In the present invention, the partition is preferably connected to the tank top and spaced apart from the tank bottom.

[0092] In the present invention, one or more sampling ports are preferably provided in the middle and lower part of the first settling tank.

[0093] In the present invention, the device preferably further comprises a second gas-liquid separation tank and a filter.

[0094] In the present invention, the second gas-liquid separation tank is preferably connected to the discharge pipelines of the settled materials at the bottom of the first settling tank and the second settling tank, respectively.

[0095] In the present invention, the solid-liquid mixture outlet of the second gas-liquid separation tank is preferably connected to the filter.

[0096] In the present invention, the gas phase outlet of the second gas-liquid separation tank is preferably connected to an ethylene recycling unit.

[0097] In the present invention, the liquid phase outlet of the filter is preferably connected to a separation unit.

[0098] In the present invention, the filter is preferably further provided with an ethylene polymer solid phase outlet.

[0099] In the present invention, the second sedimentation tank is preferably connected to the clear liquid buffer tank via a discharge pipeline disposed at the upper portion of the tank body.

[0100] In the present invention, the clear liquid buffer tank is preferably connected to the gas-liquid separation tank via a discharge pipeline disposed at the bottom of the tank body.

[0101] In the present invention, the gas phase outlet of the gas-liquid separation tank is preferably connected to an ethylene recycling unit.

[0102] In the present invention, the liquid phase outlet of the gas-liquid separation tank is preferably connected to a separation unit.

[0103] The present invention is to complete and refine the overall process device, better improve the efficiency and product quality of the ethylene selective oligomerization reaction, and further ensure the long-term continuous and stable operation of the production system. The above-mentioned continuous ethylene selective oligomerization reaction device can specifically be composed of the following:

[0104] The continuous ethylene selective polymerization device comprises a reaction kettle, a quenching kettle, two sedimentation tanks, a clear liquid buffer tank, two gas-liquid separation tanks and a filter in sequence.

[0105] The reactor is connected to ethylene, solvent and catalyst feed lines;

[0106] The quenching kettle is connected to a quenching agent feed line;

[0107] The reaction kettle, quenching kettle and clear liquid buffer tank are respectively connected to subsequent equipment through bottom valves interlocked with their own liquid levels;

[0108] The sedimentation tank is connected to subsequent equipment through an overflow pipeline at its upper part, and is connected to a gas-liquid separation tank and a filter at its bottom.

[0109] Specifically, the reactor is provided with a plurality of feed nozzles on its reactor wall, and the feed nozzles are connected to the ethylene and solvent lines. Preferably, the feed nozzles are provided with four opposite feed nozzles at 15% and 45% of the reactor volume, respectively.

[0110] Specifically, the settling tank is provided with a drainage plate and a partition plate, and a sampling port is provided in the middle and lower part of the tank wall. Preferably, the sampling port is provided at 20%, 15%, 10% and 5% of the tank volume, respectively.

[0111] Specifically, the filter is a bag filter with a filtration accuracy of 1 to 300 μm.

[0112] The present invention provides a continuous ethylene selective oligomerization process, comprising the following steps:

[0113] 1) continuously feeding the solvent, catalyst and ethylene into the reactor to carry out the selective polymerization of ethylene, and conveying the reaction liquid to the quenching kettle to maintain the liquid level of the reactor;

[0114] 2) After continuously feeding the quenching agent into the quenching kettle to quench the activity of the catalyst, the quenched reaction liquid is then transported to the first settling tank to maintain the liquid level of the quenching kettle;

[0115] 3) The quenched reaction liquid is guided by a guide plate in the first settling tank to slow down the flow rate, and is precipitated with the assistance of a baffle. The insoluble polymer is deposited at the bottom of the tank, and the upper liquid enters the second settling tank through an overflow pipeline. After secondary sedimentation, the upper clear liquid enters the clear liquid buffer tank through an overflow pipeline;

[0116] 4) The clear liquid in the clear liquid buffer tank is transported to the gas-liquid separation tank to maintain the liquid level of the clear liquid buffer tank;

[0117] 5) After the clear liquid in the gas-liquid separation tank is separated into gas and liquid, the gas is recycled and the liquid enters the subsequent distillation separation unit.

[0118] The present invention firstly continuously feeds solvent, catalyst and ethylene into a reaction kettle to carry out ethylene selective polymerization reaction, and then transports reaction liquid to a quenching kettle to maintain the liquid level of the reaction kettle.

[0119] In the present invention, the pressure in the reactor is preferably 4-6 MPa, more preferably 4.2-5.8 MPa, and more preferably 4.5-5.5 MPa.

[0120] In the present invention, the temperature in the reaction kettle is preferably 55-60°C, more preferably 56-59°C, and more preferably 57-58°C.

[0121] In the present invention, the liquid level control range of the reaction kettle is preferably 20% to 80% of the kettle volume, more preferably 30% to 70%, and more preferably 40% to 60%.

[0122] In the present invention, the amount of reaction liquid transported from the reactor to the back path each time is preferably 1% to 20% of the reactor volume, more preferably 5% to 16%, and more preferably 9% to 12%.

[0123] The present invention continuously feeds the quenching agent into the quenching kettle to quench the activity of the catalyst, and then transports the quenched reaction liquid to the first settling tank to maintain the liquid level of the quenching kettle.

[0124] In the present invention, the liquid level control range of the quenching kettle is preferably 20% to 80% of the kettle volume, more preferably 30% to 70%, and more preferably 40% to 60%.

[0125] In the present invention, the amount of reaction liquid transported to the back path by the quenching kettle each time is preferably 1% to 20% of the kettle volume, more preferably 5% to 16%, and more preferably 9% to 12%.

[0126] The quenched reaction liquid is guided in the first sedimentation tank by a guide plate to slow down the flow rate, and is precipitated with the assistance of a partition, and the insoluble polymer is deposited at the bottom of the tank, and the upper liquid enters the second sedimentation tank through an overflow pipeline. After secondary sedimentation, the upper clear liquid enters the clear liquid buffer tank through an overflow pipeline.

[0127] In the present invention, the liquid level control range of the clear liquid buffer tank is preferably 20% to 80% of the kettle volume, more preferably 30% to 70%, and more preferably 40% to 60%.

[0128] In the present invention, the amount of reaction liquid transported to the back path by the clear liquid buffer tank each time is preferably 1% to 20% of the kettle volume, more preferably 5% to 16%, and more preferably 9% to 12%.

[0129] In the present invention, it is preferred to take samples through the sampling port of the first settling tank and / or the second settling tank to monitor the sedimentation of insoluble matter. When sampling finds that insoluble matter has aggregated and settled, the slurry after sedimentation is discharged into the second gas-liquid separation tank through the bottom valve at the bottom of the settling tank and the discharge volume is determined according to the position of the settling tank where the sampling port is located and the actual liquid level change in the settling tank. It is more preferred to take samples through the sampling port of the first settling tank or the second settling tank.

[0130] In the present invention, the slurry after sedimentation is preferably subjected to gas-liquid separation, the gas is incorporated into the recycling system, the slurry liquid enters the filter to filter out the insoluble ethylene polymer, and the filtrate enters the separation unit with the clear liquid.

[0131] The present invention then transports the clear liquid in the clear liquid buffer tank to the gas-liquid separation tank to maintain the liquid level of the clear liquid buffer tank.

[0132] After the clear liquid in the gas-liquid separation tank of the present invention is separated into gas and liquid, the gas is recycled and the liquid enters the subsequent distillation separation unit.

[0133] The present invention is to complete and refine the overall process device, better improve the efficiency and product quality of the ethylene selective oligomerization reaction, and further ensure the long-term continuous and stable operation of the production system. The above-mentioned continuous ethylene selective oligomerization reaction process can specifically be the following steps:

[0134] The method for continuous ethylene selective oligomerization using the above device comprises the following steps:

[0135] The solvent, catalyst and ethylene are continuously introduced into the reactor in proportion, and the ethylene selective polymerization reaction is carried out at a predetermined pressure and temperature. A certain amount of reaction liquid is transported to the quenching kettle through the bottom valve interlocked with the liquid level of the reactor to maintain the liquid level of the reactor.

[0136] The quenching agent is continuously and quantitatively introduced into the quenching kettle to quench the activity of the catalyst. A certain amount of quenched reaction liquid is delivered to the settling tank A through the bottom valve interlocked with the liquid level of the quenching kettle to maintain the liquid level of the quenching kettle.

[0137] The quenched reaction liquid is guided by a drainage plate in sedimentation tank A to slow down the flow rate, and settles with the assistance of a partition. The insoluble polymer gradually settles at the bottom of the tank, and the upper clear liquid enters sedimentation tank B through an overflow pipeline. After secondary sedimentation, the upper clear liquid enters the clear liquid buffer tank through an overflow pipeline.

[0138] The clear liquid buffer tank delivers a certain amount of clear liquid to the gas-liquid separation tank A through the bottom valve interlocked with its liquid level to maintain the liquid level of the clear liquid buffer tank.

[0139] After the clear liquid is separated into gas and liquid, the gas is recycled and the liquid enters the subsequent distillation separation unit.

[0140] Settling tanks A and B are sampled regularly from the sampling ports on their sides to monitor the settling of insoluble matter. When sampling finds insoluble matter that has accumulated and settled, the settled slurry is discharged to gas-liquid separation tank B through the bottom valve at the bottom of the settling tank and the discharge volume is determined based on the position of the sampling port in the settling tank and the actual liquid level change in the settling tank.

[0141] After the sedimentation liquid is separated into gas and liquid, the gas is incorporated into the recycling system and the slurry liquid enters the filter.

[0142] The filter filters out the insoluble ethylene polymer, and the filtrate enters the separation unit along with the clear liquid.

[0143] Specifically, the liquid level control range of the reactor is 20% to 80% of the reactor volume, and the amount of reaction liquid transported to the rear path each time through the liquid level interlocked bottom valve is 1% to 20% of the reactor volume.

[0144] Specifically, the liquid level control range of the quenching kettle is 20% to 80% of the kettle volume, and the amount of reaction liquid transported to the rear path each time through the bottom valve of the liquid level interlock is 1% to 20% of the kettle volume.

[0145] Specifically, the liquid level control range of the clear liquid buffer tank is 20% to 80% of the kettle volume, and the amount of reaction liquid transported to the rear path each time through the liquid level interlocked bottom valve is 1% to 20% of the kettle volume.

[0146] The core of the above-mentioned device and method of the present invention lies in the cleaning and discharge of insoluble matter in the entire reaction system. As for other aspects of the polymerization process, such as raw material purification, reaction heat removal, material recycling, etc., there have been too many reports, which can all be used as reference. The present invention has no special requirements for this and will not be repeated here.

[0147] The continuous ethylene selective oligomerization device and method disclosed in the present invention feeds ethylene through a feed nozzle arranged on the wall of the reactor and regularly washes polymer attachments on the inner surface of the reactor with a high-pressure solvent jet; the reaction liquid after quenching is subjected to two-stage sedimentation, and the upper clear liquid directly enters the subsequent distillation separation unit, thereby realizing continuous operation; the slurry with high insoluble content in the lower layer after precipitation and concentration is discharged from the system in a centralized manner, and then solid-liquid separation is performed, thereby avoiding the problems of easy filter blockage, ineffective backwashing, frequent switching, difficult cleaning, and influence on continuous operation when filtering directly in a continuous and high-pressure system. The present invention provides a solution to the insoluble ethylene polymers produced by side reactions during continuous ethylene selective oligomerization, thereby realizing long-term continuous and stable operation of the device.

[0148] See also Figure 1 , Figure 1 The present invention provides a schematic diagram of the process flow of a continuous ethylene selective oligomerization device.

[0149] like Figure 1As shown, according to a continuous ethylene selective polymerization device provided by the present invention, we debugged and assembled the corresponding device. The device sequentially comprises a reactor, a quenching kettle, two sedimentation tanks, a clear liquid buffer tank, two gas-liquid separation tanks and a filter. The reactor is connected to the ethylene, solvent and catalyst feed lines; the quenching kettle is connected to the quenching agent feed line; the reactor, the quenching kettle and the clear liquid buffer tank are respectively connected to the subsequent equipment through the bottom valve interlocked with their own liquid levels; the sedimentation tank is connected to the subsequent equipment through the overflow pipeline at the upper part thereof, and is connected to the gas-liquid separation tank and the filter at the bottom.

[0150] The reactor is provided with four feed nozzles at 15% and 45% of its reactor volume. A drainage plate and a partition are provided inside the sedimentation tank, and a sampling port is provided on the tank wall at 20%, 15%, 10%, and 5% of the tank volume. The filter is a bag filter with a filtration accuracy of 100μm.

[0151] The present invention provides a continuous ethylene selective oligomerization device and method. The core of the present invention is to clean and discharge the insoluble matter in the entire reaction system. Without affecting the continuous operation of the ethylene selective oligomerization device, the insoluble ethylene polymer produced by the side reaction is discharged to eliminate the influence of the insoluble matter, thereby achieving long-term continuous and stable operation of the device.

[0152] The present invention performs secondary sedimentation on the polymerization reaction liquid containing insoluble polymers, discharges the settled insolubles from the continuous system in a centralized manner, and then performs conventional filtration. The method avoids the drawbacks of easy clogging of the filter, ineffective backwashing, frequent switching, and difficult cleaning when the insoluble polymers are filtered online in a continuous high-pressure system, does not affect the continuous operation of the device, and reduces the frequency and intensity of the filtering operation, thereby achieving the discharge of the insoluble polymers and eliminating the harm to the device and the subsequent distillation and separation unit.

[0153] Moreover, the guide plate in the settling tank of the present invention can guide the reaction liquid to slowly merge into the settled reaction liquid, reducing impact and disturbance; the partition in the settling tank plays an auxiliary sedimentation role; the overflow pipeline also slows down the flow rate of the supernatant, which is beneficial to the sedimentation of the insoluble polymer.

[0154] At the same time, the four sampling ports provided at different volumes on the side of the sedimentation tank of the present invention can directly take out slurry samples at corresponding depths of the sedimentation tank to monitor the sedimentation state of the insoluble polymer, and can adjust the sedimentation time and the amount of liquid discharged each time according to the continuous reaction situation, thereby improving the response flexibility.

[0155] Furthermore, the reactor of the present invention is provided with four feed nozzles at 15% and 45% of the volume, respectively, which are opposite to each other. When feeding continuously, the nozzles serve as the feed ports of ethylene, so that ethylene directly enters the reaction liquid, thereby improving the mass transfer effect. When cleaning the attachments in the reactor, the solvent line can be switched to flush with a high-pressure solvent jet, with four nozzles at each horizontal position, and a spray angle of 45°, covering the inner surface of the space occupied by the liquid phase when the reactor is operating normally. In addition, the present invention also automatically controls the equipment liquid level and the amount of each delivery through a bottom valve interlocked with the corresponding equipment liquid level, thereby realizing continuous material delivery, with a high degree of automation.

[0156] Experimental results show that the device and method provided by the present invention can discharge 99.3% of the insoluble polymer solids produced by ethylene polymerization from the continuous system without affecting the continuous operation of the device, and the operation cycle is greater than 90 days; the liquid in the sedimentation tank has a significant sedimentation effect under the action of the drainage plate and the partition, and the upper clear liquid obtained by controlling the discharge amount of the sedimentation tank does not contain insoluble polymer solids; the inner surface of the reactor and the stirring paddle are washed with a solvent through a nozzle, so that there is no large amount of polymer adhesion and aggregation.

[0157] In order to further illustrate the present invention, a continuous ethylene selective oligomerization reaction device and a reaction process thereof provided by the present invention are described in detail below in conjunction with examples. However, it should be understood that these examples are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

[0158] The present invention has no particular limitation on the sources of the raw materials in the following examples, and the raw materials can be prepared by methods well known to those skilled in the art or purchased from the market.

[0159] Example 1

[0160] This embodiment uses the above-mentioned device, adopting Figure 1 The process and method were used to carry out a continuous ethylene selective polymerization reaction.

[0161] Methylcyclohexane is used as a polymerization reaction solvent, isooctyl alcohol is used as a quenching agent, a chromium complex of an isopropyl PNP ligand is a main catalyst, and methylaluminoxane is used as a co-catalyst. Purified methylcyclohexane (water and oxygen contents are both less than 5 ppm), the main catalyst and the co-catalyst diluted with the solvent are continuously fed into a reactor; the feeding amount of the solvent and the catalyst is controlled by a metering pump so that the catalyst concentration (chromium mass fed into the reactor per hour / liquid volume fed into the reactor) is maintained at 10 umol / L, and the aluminum-chromium ratio is 600; the ethylene feeding amount is controlled by a gas flow meter and enters the reactor through eight nozzles on the reactor so that the pressure in the reactor is maintained at 5.0 MPa; the temperature of the reactor is controlled to be maintained at 55-60° C. A polymerization reaction occurs in the reactor; the upper limit of the reactor liquid level is set to 60% of the reactor volume, and the lower limit is set to 50% of the reactor volume; through a bottom valve interlocked with the reactor liquid level, 10% of the reaction liquid of the reactor volume is discharged to the quenching kettle each time to maintain a certain liquid level range of the reactor. A metered amount of isooctyl alcohol is continuously introduced into the quenching kettle through a metering pump to maintain the ratio of the quenching amount to the chromium amount in the kettle at 300; the upper limit of the quenching kettle liquid level is set at 60% of the kettle volume, and the lower limit is set at 40% of the kettle volume. Through the bottom valve interlocked with the quenching kettle liquid level, 20% of the reaction liquid of the quenching kettle volume is discharged to the sedimentation tank A each time to maintain the quenching kettle liquid level. The quenched reaction liquid has no reaction activity and will not continue to react. In the settling tank A, the flow rate is slowed down by the guide plate, and the sedimentation is assisted by the partition. The insoluble polymer gradually settles at the bottom of the tank, and the upper clear liquid enters the settling tank B through the overflow pipeline. After secondary sedimentation, the upper clear liquid enters the clear liquid buffer tank through the overflow pipeline; the upper limit of the clear liquid buffer tank is set to 60% of the tank volume, and the lower limit is set to 40% of the tank volume. Through the bottom valve interlocked with the clear liquid buffer tank level, 20% of the tank volume of the reaction liquid is discharged to the gas-liquid separation tank A each time to maintain the clear liquid buffer tank level. After the clear liquid is separated by gas and liquid, the gas is reused and the liquid enters the subsequent distillation separation unit.

[0162] After the device has been running continuously for 8 hours, the settling tank A takes a sample of 10 ml from the sampling port on the side of the tank every 1 hour, and monitors its sedimentation according to the content of insoluble matter. In this embodiment, after the device has been running for 12 hours, insoluble solids appear when the settling tank A is sampled at 5% of the tank volume, and the insoluble matter content increases with sampling. After 22 hours, the insoluble solid content remains basically unchanged, indicating that the insoluble matter deposition at 5% reaches the maximum. The bottom valve of the settling tank A is opened to discharge the slurry after sedimentation of 5% of the tank volume into the gas-liquid separation tank B; the sampling interval of the settling tank B is 5 hours. After multiple sampling and analysis, it is finally determined that the settling tank A discharges 5% of the tank volume of the sedimentation liquid to the gas-liquid separation tank B every 20 hours and the settling tank B every 58 hours. After the sedimentation liquid is separated from the gas and liquid, the gas is merged into the recycling system, and the slurry liquid enters the filter. The filter uses a conventional bag filter, 100μm nylon filter bag, which is easy to operate and clean. The insoluble polymer is filtered out and the filtrate enters the distillation separation unit. The reactor is cleaned of attachments every 15 days. The reactor liquid level is reduced to 5%, the pressure is reduced to 2MPa, the nozzle is cut to the high-pressure solvent pipeline, and the attachments in the reactor are flushed. After completion, it continues to operate according to the continuous polymerization process. The attachments that are cleaned are finally discharged from the system with the reaction liquid after quenching, sedimentation, filtration, etc.

[0163] The device was operated stably and continuously for 90 days under the above-mentioned operating process. During this period, no abnormality caused by insoluble polymer solids occurred. The polymers produced by the reaction were successfully separated from the system, and there was no solid insoluble matter in the supernatant and the filtrate.

[0164] When the unit was shut down for maintenance, it was found that all pipelines were unobstructed and there was no excessive solid attachment on the equipment surface. The catalyst activity was 1278kg / gCr.h, 1-hexene selectivity was 17.31%, 1-octene selectivity was 66.78%, and the separated polymer selectivity was 0.73%.

[0165] Comparative Example 1

[0166] The device of Example 1 was compared, and the settling tanks A, B, gas-liquid separation tank B and the filter were cut out of the system, and two parallel filters were connected between the quenching kettle and the clear liquid buffer tank, and a replaceable stainless steel filter element was used. According to the raw materials and process parameters of Example 1, continuous ethylene selective polymerization was carried out, methylcyclohexane was used as the reaction solvent, isooctyl alcohol was used as the quenching agent, the chromium complex of isopropyl PNP ligand was used as the main catalyst, methylaluminoxane was used as the co-catalyst, the catalyst concentration of the reactor was maintained at 10umol / L, the aluminum-chromium ratio was 600, the pressure in the reactor was 5.0MPa, and the temperature control of the reactor was 55-60°C. The high and low limit settings of the liquid level of the reactor, the quenching kettle and the clear liquid buffer tank were the same as those in Example 1.

[0167] During the continuous operation of the device, the insoluble polymer solids are filtered through the filter. When the filter is blocked, backwashing is performed. When backwashing is ineffective or the insoluble matter is filled, another filter is switched to continue to maintain the continuous operation of the device, and the filter is disassembled and cleaned. Through operation, it was found that when using a 100μm stainless steel sintered filter element, the filter was blocked at 16h, the pressure difference before and after the filter was >3MPa, and backwashing was ineffective. Another filter was switched to maintain the continuous operation of the device. At 28h, the second filter had the same problem, and the continuous operation of the device was terminated.

[0168] The filter elements were replaced with 100μm stainless steel wound filter elements, and the above continuous operation was carried out. The filter was blocked at 30h, and the pressure difference between the front and rear was >2MPa. It could continue to operate after backwashing. At 38h, it was blocked again, and it continued to operate after backwashing. At 44h, after blocking, backwashing was ineffective, the filter was filled with insoluble matter, and it was switched to another one. The two filters maintained the device operation for 73h in total. The wound filter element is more suitable for polymer (especially waxy) filtration than the sintered type.

[0169] Comparative Example 1 performs insoluble matter filtration in a continuous system. When the filter is blocked and another filter is switched, the cut-in filter needs to be replaced with ethylene, and the cut-out filter needs to be switched between high pressure / normal pressure, depressurized, replaced with nitrogen, and then disassembled and cleaned, or the filter element needs to be replaced. For a device that requires long-term operation, the operation is frequent and complicated, and any abnormality will affect the continuous stability of the device. In Example 1, after the insoluble matter is precipitated, the device is discharged regularly and concentratedly, and a conventional bag filter is used. A nylon filter bag can meet the requirements of use, which is easy to operate, low frequency, and more importantly, does not affect the continuity of the device and has a long operation cycle.

[0170] Example 2

[0171] This device is applicable to continuous ethylene selective polymerization. For different catalytic systems and process parameters, the amount of solids produced by the polymerization reaction is different. The device needs to determine the sedimentation rate of insoluble solids by sampling the sedimentation tank, determine the thickness of the solid sedimentation and aggregation layer at the bottom of the sedimentation tank and the amount of slurry that needs to be discharged to the outside of the system, that is, the gas-liquid separation tank B each time.

[0172] In this embodiment, cyclohexane is used as the polymerization solvent, isooctyl alcohol is used as the quencher, the chromium complex of the ligand of patent CN113444126A is the main catalyst, and modified methylaluminoxane is the co-catalyst. The above-mentioned device is used. Figure 1 processes and methods.

[0173] Purified cyclohexane (water and oxygen contents are both less than 5ppm), main catalyst and co-catalyst diluted with solvent are continuously introduced into the reactor; the feeding amount of solvent and catalyst is controlled by a metering pump to maintain the catalyst concentration (chromium mass entering the reactor per hour / liquid volume entering the reactor) at 5umol / L and the aluminum-chromium ratio at 500; the ethylene feeding amount is controlled by a gas flow meter and enters the reactor through eight nozzles on the reactor to maintain the pressure in the reactor at 5.0MPa; the temperature of the reactor is controlled to maintain at 55-60°C; a polymerization reaction occurs in the reactor; the upper limit of the reactor liquid level is set to 60% of the reactor volume, and the lower limit is set to 50% of the reactor volume, and 10% of the reaction liquid of the reactor volume is discharged to the quenching kettle each time through a bottom valve interlocked with the reactor liquid level to maintain the reactor in a certain liquid level range. The quenching kettle is continuously fed with metered isooctyl alcohol through a metering pump to maintain the ratio of the quenching dosage to the chromium content in the kettle at 250; the upper limit of the quenching kettle liquid level is set at 60% of the kettle volume, and the lower limit is set at 40% of the kettle volume. Through the bottom valve interlocked with the quenching kettle liquid level, 20% of the reaction liquid of the quenching kettle volume is discharged to the sedimentation tank A each time to maintain the quenching kettle liquid level. The upper limit of the clear liquid buffer tank liquid level is set at 60% of the tank volume, and the lower limit is set at 40% of the tank volume. Through the bottom valve interlocked with the clear liquid buffer tank liquid level, 20% of the reaction liquid of the tank volume is discharged to the gas-liquid separation tank A each time to maintain the clear liquid buffer tank liquid level. After the clear liquid is separated by gas and liquid, the gas is reused and the liquid enters the subsequent distillation separation unit. After the device has been running continuously for 14 hours, the settling tank A samples 10 ml from the sampling port on the side of the tank every hour to monitor its sedimentation. In this embodiment, after the device has been running for 20 hours, insoluble solids appear when sampling at 5% of the tank volume, and the insoluble content increases with sampling. After 30 hours, the insoluble sedimentation at 5% reaches a stable value, and the bottom valve of the settling tank A is opened to discharge the 5% of the tank volume of the settled slurry into the gas-liquid separation tank B; the sampling interval of the settling tank B is 10 hours. After multiple sampling and analysis, it is finally determined that the settling tank A discharges 5% of the tank volume of the sedimentation liquid to the gas-liquid separation tank B every 31 hours and the settling tank B every 90 hours. After the gas-liquid separation of the sedimentation liquid, the gas is incorporated into the reuse system, and the slurry liquid enters the filter. The filter uses a conventional bag filter, a 50μm nylon filter bag, to filter out the insoluble polymer, and the filtrate enters the distillation separation unit. The reactor was cleaned of deposits every 20 days, and the operation was the same as in Example 1.

[0174] The device also operated stably and continuously for 90 days under the above operation flow, during which no abnormality caused by insoluble polymer solids occurred, the polymers produced by the reaction were successfully separated from the system, and there was no solid insoluble matter in the supernatant and the filtrate. When the device was shut down for maintenance, it was found that all pipelines were unobstructed, and there was basically no solid attachment on the surface of the equipment, which was less than that in Example 1. The catalyst activity was 1885kg / gCr.h, the selectivity of 1-hexene was 18.55%, the selectivity of 1-octene was 67.21%, and the selectivity of the separated polymer was 0.18%.

[0175] The above is a detailed introduction to a continuous ethylene selective polymerization device and method provided by the present invention. The principle and implementation method of the present invention are described in detail using specific examples herein. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims, and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the textual expression of the claims, or if they include equivalent structural elements that are not substantially different from the textual expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A continuous ethylene selective oligomerization reaction device, characterized in that: include: Reactor; A quenching kettle connected to the reactor; A first settling tank connected to the quenching kettle; a second settling tank connected to the first settling tank; a clear liquid buffer tank connected to the second settling tank; A gas-liquid separation tank connected to the clear liquid buffer tank; The reactor is connected with an ethylene feed pipeline, a solvent feed pipeline and a catalyst feed pipeline; One or more feed nozzles are arranged on the wall of the reactor; The feed nozzle is connected to an ethylene feed pipeline and / or a solvent feed pipeline; The top of the reactor is also provided with a solvent feed pipeline which is not connected to the nozzle; The device also includes a second gas-liquid separation tank and a filter; The second gas-liquid separation tank is respectively connected to the discharge pipelines of the sedimentation materials at the bottom of the first sedimentation tank and the second sedimentation tank; The solid-liquid mixture outlet of the second gas-liquid separation tank is connected to the filter; The gas phase outlet of the second gas-liquid separation tank is connected to the ethylene recycling unit; The liquid phase outlet of the filter is connected to a separation unit; The filter is also provided with an ethylene polymer solid phase outlet.

2. The device according to claim 1, characterized in that The feed nozzle is arranged at a distance of 15% and / or 45% of the volume of the kettle from the bottom of the kettle.

3. The device according to claim 1, characterized in that The reaction kettle is connected to the quenching kettle via a discharge pipeline arranged at the bottom of the kettle; The quenching kettle is connected with a quenching agent feeding pipeline; The quenching kettle is connected to the first settling tank via a discharge pipeline arranged at the bottom of the kettle; The first settling tank is provided with a drainage plate and a partition; The partition is specifically arranged along the height direction of the settling tank; The partition is connected to the tank top and is spaced apart from the tank bottom.

4. The device according to claim 1, characterized in that The middle and lower part of the first settling tank is also provided with one or more sampling ports; The first settling tank is connected to the second settling tank via a discharge pipeline arranged at the upper part of the tank body; A guide plate and a partition are arranged in the second settling tank.

5. The device according to claim 4, characterized in that The partition is specifically arranged along the height direction of the settling tank; The partition is connected to the tank top and is spaced apart from the tank bottom; One or more sampling ports are also provided in the middle and lower part of the first settling tank.

6. The device according to claim 1, characterized in that The second sedimentation tank is connected to the clear liquid buffer tank via a discharge pipeline arranged at the upper part of the tank body; The clear liquid buffer tank is connected to the gas-liquid separation tank via a discharge pipeline arranged at the bottom of the tank body; The gas phase outlet of the gas-liquid separation tank is connected to the ethylene recycling unit; The liquid phase outlet of the gas-liquid separation tank is connected to the separation unit.

7. A process using the continuous ethylene selective oligomerization reaction device according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) continuously feeding the solvent, catalyst and ethylene into the reactor to carry out the selective polymerization of ethylene, and conveying the reaction liquid to the quenching kettle to maintain the liquid level of the reactor; 2) After continuously feeding the quenching agent into the quenching kettle to quench the activity of the catalyst, the quenched reaction liquid is then transported to the first settling tank to maintain the liquid level of the quenching kettle; 3) The quenched reaction liquid is guided by a guide plate in the first settling tank to slow down the flow rate, and is precipitated with the assistance of a baffle. The insoluble polymer is deposited at the bottom of the tank, and the upper liquid enters the second settling tank through an overflow pipeline. After secondary sedimentation, the upper clear liquid enters the clear liquid buffer tank through an overflow pipeline; 4) The clear liquid in the clear liquid buffer tank is transported to the gas-liquid separation tank to maintain the liquid level of the clear liquid buffer tank; 5) After the clear liquid in the gas-liquid separation tank is separated into gas and liquid, the gas is recycled and the liquid enters the subsequent distillation separation unit.

8. The process according to claim 7, characterized in that The pressure in the reactor is 4-6 MPa; The temperature in the reactor is 55-60°C; The liquid level control range of the reactor is 20% to 80% of the reactor volume; The amount of reaction liquid transported to the rear path by the reactor each time is 1% to 20% of the reactor volume.

9. The process according to claim 7, characterized in that The liquid level control range of the quenching kettle is 20% to 80% of the kettle volume; The amount of reaction liquid transported to the back path by the quenching kettle each time is 1% to 20% of the kettle volume; The liquid level control range of the clear liquid buffer tank is 20% to 80% of the kettle volume; The amount of reaction liquid transported to the rear path by the clear liquid buffer tank each time is 1% to 20% of the kettle volume.

10. The process according to claim 7, characterized in that Sampling is performed through the sampling port of the first settling tank and / or the second settling tank to monitor the settling of insoluble matter. When the insoluble matter that has accumulated and settled is found during sampling, the slurry after settling is discharged into the second gas-liquid separation tank through the bottom valve at the bottom of the settling tank and the discharge amount is determined according to the position of the settling tank where the sampling port is located and the actual liquid level change in the settling tank; After the precipitated slurry is separated into gas and liquid, the gas is incorporated into the recycling system, the slurry liquid enters the filter to filter out the insoluble ethylene polymer, and the filtrate enters the separation unit with the clear liquid.

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