A flexible switching production device and production method for low-cis butadiene rubber

Abstract

The application discloses a flexible switching production device and a production method for low-cis butadiene rubber, and the production device comprises a feeding system, a polymerization system, a flash evaporation system and a condensation system which are sequentially connected and can be flexibly switched between a continuous polymerization mode and an intermittent polymerization mode. The feeding system comprises a butadiene refining unit, a solvent refining unit, a continuous polymerization auxiliary unit and an intermittent polymerization auxiliary unit. The polymerization system at least comprises a first polymerization kettle and a second polymerization kettle which are arranged in parallel. In the continuous polymerization mode, the feeding system is connected with the bottom feeding ports of the polymerization kettles, and the flash evaporation system is connected with the top discharging ports of the polymerization kettles. In the intermittent polymerization mode, the butadiene refining unit and the solvent refining unit are connected with the bottom feeding ports of the polymerization kettles, the intermittent polymerization auxiliary unit is connected with the top feeding ports of the polymerization kettles, and the flash evaporation system is connected with the bottom discharging ports of the polymerization kettles. Through the device and the method, products with high quality and high productivity can be provided, and the continuous polymerization mode and the intermittent polymerization mode can be flexibly switched.

Description

Technical Field

[0001] This invention belongs to the field of low-cis-butadiene rubber preparation technology, and particularly relates to a flexible switching production equipment and production method for low-cis-butadiene rubber. Background Technology

[0002] Low-cis-butadiene rubber (LCBR) comes in many varieties and grades, and its production processes are divided into continuous polymerization and batch polymerization. The former is further divided into single-reactor and multi-reactor processes. Currently, the main continuous polymerization processes are represented by Firestone's multi-reactor continuous polymerization (USA) and Asahi's single-reactor continuous polymerization (Japan), while the batch polymerization process is represented by Phillips' process (USA). In multi-reactor continuous polymerization, more than 80% of the polymerization reaction is completed in the first and second reactors. The material needs to be pre-cooled to a sufficiently low temperature before entering the reactors to absorb the heat of reaction and control the polymerization temperature. However, due to the large number of reactors, multi-reactor continuous polymerization is prone to creating many "dead zones," and the long pipelines through which the rubber solution passes are prone to gel buildup, which can negatively impact production and even cause accidents. Furthermore, due to the long process flow, the temperature during the reaction is difficult to control, easily leading to hot spots. Influenced by heat and oxygen, gel formation can occur, and excessively high gel content is a major factor affecting the quality of LCBR products. The single-reactor continuous polymerization process has high production efficiency and stable production, but the polymerization reactor has a large volume and the product has a high gel content.

[0003] Batch polymerization processes are easy to control and can produce a wide variety of product grades. A three-reactor operation system with different reactors for feeding, polymerization, and discharging is generally used, resulting in high efficiency and minimal transition material. However, due to the prolonged intermittent operation of the polymerization reactors, reactive polymer residues tend to remain in various locations such as the reactor walls, dead corners, agitators, valves, and pipelines after each operation. When new material is introduced, long-chain branching can easily occur in these areas, leading to gel formation. Furthermore, the randomness of gel shedding makes it difficult to control the gel content in the product, severely impacting the performance of LCBR products.

[0004] Invention CN107522806B discloses a continuous polymerization method specifically for synthesizing Mooney rare earth cis-butadiene rubber with a narrow molecular weight distribution. The catalyst used in this method consists of five substances: rare earth phosphate compound, diene, hydrogenated alkyl aluminum, organochloride, and alkyl aluminum. The catalyst is continuously aged by adding the five substances in a specific order and with a defined residence time. The aged catalyst is then continuously fed into the polymerization reactor for continuous butadiene polymerization. This method directly synthesizes rare earth cis-butadiene rubber with a Menyley value of 55–100, a number-average molecular weight ≥180,000, and a molecular weight distribution of 1.3–2.5. The resulting vulcanized rubber exhibits excellent performance and processing characteristics.

[0005] Invention CN111848849B discloses a continuous preparation process for nickel-based and rare-earth-based cis-butadiene rubber, comprising: continuously introducing butadiene oil and one of a nickel-based catalyst and a rare-earth-based catalyst into a polymerization reaction unit of a polymerization apparatus to carry out a polymerization reaction, obtaining a nickel-based or rare-earth-based cis-butadiene rubber solution; then introducing the solution into a coagulation unit for coagulation to obtain nickel-based or rare-earth-based cis-butadiene rubber; wherein the butadiene oil includes butadiene monomer and solvent, and its oxygen content is less than or equal to 20 mg / kg and its water value is less than or equal to 50 ppm; wherein, when preparing nickel-based cis-butadiene rubber, the introduction of the rare-earth-based catalyst is stopped, and the butadiene oil and the nickel-based catalyst are introduced into the polymerization reaction unit; when preparing rare-earth-based cis-butadiene rubber, the introduction of the nickel-based catalyst is stopped, and the butadiene oil and the rare-earth-based catalyst are introduced into the polymerization reaction unit. This invention can achieve flexible switching between the production of nickel-based and rare-earth-based cis-butadiene rubber on the same polymerization apparatus without shutdown and cleaning.

[0006] Invention CN107474174B discloses a method for producing butadiene rubber, comprising: introducing 1,3-butadiene monomer and solvent into a polymerization reactor under solution polymerization conditions for polymerization reaction; recycling a portion of the butadiene rubber solution obtained at the outlet of the polymerization reactor back to the inlet of the polymerization reactor; and introducing the remaining butadiene rubber solution as a crude product into a subsequent processing unit. By returning the polymerized solution to the polymerization reactor, the amount of solvent used in the polymerization process is reduced, thereby reducing the solvent consumption per ton of dry rubber and consequently reducing the steam consumption for solvent recovery, resulting in a good energy-saving effect. It is also indicated that the specific production method for butadiene rubber can adopt either a batch process operation mode or a continuous process operation mode.

[0007] While the aforementioned inventions all involve continuous or batch polymerization processes for butadiene rubber, they all improve production efficiency through modifications to a single production process. They do not focus on utilizing the same production equipment to switch between continuous and batch polymerization processes, ensuring production capacity while leveraging the advantages of each process. The main limiting factors include controlling the polymerization temperature and improving heat removal capabilities; such process switching solutions are currently rarely reported.

[0008] Therefore, how to flexibly switch between continuous and intermittent polymerization modes in the same production equipment, make full use of the advantages of the two polymerization modes, remove heat in time, ensure uniform temperature distribution in the reactor, strictly control gel content, and at the same time meet the quality requirements of low cis-butadiene rubber products and production line capacity requirements has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] To address the shortcomings of the existing technology, the present invention aims to provide a flexible switching production equipment and method for low-cis-cis butadiene rubber. By designing pipeline connections and switching methods for continuous polymerization and batch polymerization modes, and by setting up heat removal methods such as a stirring structure with a wide viscosity range, heat removal is timely when switching production modes, resulting in low gel content and stable quality of the product, thus achieving a flexible switching method for continuous / batch polymerization of low-cis-cis butadiene rubber.

[0010] In a first aspect, the present invention provides a flexible switching production equipment for low-cis-cis-butadiene rubber, comprising a feeding system, a polymerization system, a flash evaporation system and a coagulation system connected in sequence;

[0011] The feeding system includes a butadiene refining unit, a solvent refining unit, a continuous polymerization aid unit for continuous polymerization mode, and a batch polymerization aid unit for batch polymerization mode.

[0012] The polymerization system includes at least a first polymerization reactor and a second polymerization reactor arranged in parallel;

[0013] The production equipment can flexibly switch between continuous polymerization mode and intermittent polymerization mode:

[0014] The continuous polymerization mode includes: a butadiene refining unit, a solvent refining unit, and a continuous polymerization aid unit, which are respectively connected to the bottom inlet of each polymerization reactor, and a flash evaporation system, which is respectively connected to the top outlet of each polymerization reactor;

[0015] The batch polymerization mode includes: a butadiene refining unit and a solvent refining unit connected to the bottom inlet of each polymerization reactor, a batch polymerization aid unit connected to the top inlet of each polymerization reactor, and a flash evaporation system connected to the bottom outlet of each polymerization reactor.

[0016] Batch polymerization is characterized by high production flexibility, easy adjustment of product types, strong adaptability, and low transition material content, but it tends to leave some active polymer residue after each operation. Continuous polymerization, on the other hand, is characterized by easy control of the reaction process, stable product quality, high production efficiency, and low consumption, but it places higher demands on the heat dissipation system. This invention, based on single-reactor continuous polymerization and single-reactor batch polymerization processes, identifies the points of convergence between their equipment and process methods, and designs pipelines and configures equipment accordingly. By utilizing their respective advantages and flexibly switching between them as needed, a production system with good adaptability and stable output and quality is obtained.

[0017] Preferably, the solvent refining unit has a first solvent discharge line and a second solvent discharge line, the first solvent discharge line being connected to the bottom inlet of each polymerization reactor;

[0018] The second solvent discharge line and the discharge line of the butadiene refining unit are both connected to the butadiene oil mixer to mix into butadiene oil. The outlet of the butadiene oil mixer is connected to the bottom feed port of each polymerization reactor.

[0019] Optionally, the downstream of the butyl oil mixer outlet may also include a butyl oil molecular sieve, a feed preheater, and / or a feed precooler.

[0020] The solvents used in the production of cis-butadiene rubber can be selected from pentane, isopentane, hexane, cyclohexane, methylcyclohexane, heptane, and octane. The solvent refining unit performs a series of treatments on the new solvent and the solvent recovered from the coagulation unit, including washing, dehydration, and deweighting. The solvent is then supplied directly to the polymerization reactor via the first solvent discharge line, and partially mixed with refined butadiene via the second solvent discharge line to form butadiene oil, providing raw materials for cis-butadiene rubber polymerization. Specifically, after the butadiene oil is mixed, it further passes through a butadiene oil molecular sieve to remove impurities from the mixture, and is then processed by a feed preheater and / or feed precooler to provide the polymerization reactor with high-purity raw materials at a suitable temperature. For example, the polymerization reaction temperature in the polymerization reactor is 50-100°C, preferably 60-95°C, and the temperature of the material entering the polymerization reactor is preferably controlled at a low level, for example, not exceeding 10°C.

[0021] Preferably, the outlet of the butadiene oil mixer and the first solvent discharge line are respectively connected to the first feed port at the bottom of each polymerization reactor, and the continuous polymerization aid unit is respectively connected to the second feed port at the bottom of each polymerization reactor; the first feed port and the second feed port are different.

[0022] Preferably, the continuous polymerization aid unit includes a continuous polymerization catalyst feed port;

[0023] The batch polymerization aid unit includes a batch polymerization catalyst feed port and a batch polymerization coupling agent feed port.

[0024] In continuous polymerization mode, the catalyst feed port is first connected to the first solvent discharge line, and is continuously added along with the solvent from the feed port at the bottom of the polymerization reactor, resulting in better dispersion of the catalyst within the reactor. In batch polymerization mode, the batch polymerization catalyst and batch polymerization coupling agent are added in stages through the feed port at the top of the polymerization reactor.

[0025] Preferably, it also includes a third polymerization reactor, each polymerization reactor having a volume of 28-35 m³. 3 At least in the batch polymerization mode, the third polymerization reactor is connected in parallel with the first and second polymerization reactors. In the continuous polymerization mode, using one of the polymerization reactors can achieve a production capacity of 55,000-65,000 tons / year. In the batch polymerization mode, connecting the three polymerization reactors in parallel also achieves a production capacity of 55,000-65,000 tons / year. The number of polymerization reactors in both modes is not limited to the above design and can be increased or decreased according to production capacity requirements and energy consumption balance. Therefore, the production equipment of this invention has high output, stable quality, flexible assembly design, and can easily expand product varieties and grades through flexible switching within the same set of production equipment, giving it a clear competitive advantage.

[0026] Preferably, each polymerization reactor has a frame-anchor combined stirring structure, which includes a rotating shaft, a frame-type stirring paddle connected to the rotating shaft, and an anchor-type stirring paddle located at the bottom of the rotating shaft.

[0027] Preferably, the frame-type agitator forms several parallel windows near the rotation axis, with the total area of ​​the windows accounting for 50-90% of the total area of ​​the frame-type agitator, and the outer diameter of the frame-type agitator accounting for 70-90% of the inner diameter of the polymerization reactor.

[0028] Preferably, the window is provided with a disturbance piece; wherein there are at least two windows, and the disturbance pieces are tilted in different directions.

[0029] Preferably, the frame-type agitator, the anchor-type agitator, and the rotating shaft have a connected cooling water passage.

[0030] In existing technologies, continuous polymerization processes involve large reactor volumes and simple reactor stirring structures, which are unsuitable for the characteristics of LCBR polymerization, resulting in lower product quality. Batch polymerization, on the other hand, involves small reactor volumes and limited production capacity. For systems producing reactive polymers like low-cis-butadiene rubber, the flow state is closely related to the molecular weight distribution. To obtain polymers with narrow molecular weight distributions, plug flow must be employed in the polymerization reactor to improve the quality of low-cis-butadiene rubber products. While multiple polymerization reactors connected in series can achieve a flow state close to plug flow, the drive components, shaft seals, and stirring structures of these reactors account for a significant proportion of the equipment cost. Therefore, this invention employs a frame-anchor combined stirring structure to increase the impeller coverage area, forming plug flow and superimposing high-intensity shear force. This allows the reactants and catalyst to mix in a very short time, achieving efficient polymerization and ensuring product quality while minimizing the risk of oxidation and decomposition of the reactive substances. Simultaneously, the impeller is equipped with a large-area open space to increase the actual reactor volume and improve the single-reactor capacity during batch polymerization.

[0031] To ensure the smooth progress of the polymerization reaction and sufficient mass and heat transfer, the heat removal system of this invention specifically employs the aforementioned frame-anchor combined stirring structure. This stirring structure can rapidly and thoroughly mix all materials and solvents, and has a good heat removal effect. Furthermore, since the LCBR polymerization process releases a large amount of heat per unit time, and the product quality is highly dependent on temperature, especially the formation of gel, which is even more sensitive to temperature, the heat removal system preferably also includes, but is not limited to, heat removal components such as jacketed coolers.

[0032] The jacketed cooler includes a cooling water jacket covering the outer wall of the polymerization reactor, a cooling water inlet at the bottom of the jacket, and several cooling water outlets at the top of the jacket. Preferably, guide ribs or flow dividers are provided on the inner wall of the jacketed cooler to ensure uniform distribution of cooling water within the jacket, fully covering the polymerization reactor wall and effectively removing heat from the reactor. Multiple outlets can be evenly distributed at the top of the jacket, allowing the heated water to be discharged promptly, thus improving the cooling water circulation rate.

[0033] Secondly, the present invention provides a flexible switching production method for low-cis-cis butadiene rubber using the aforementioned production equipment. The production method flexibly switches between continuous polymerization and batch polymerization modes by changing the connection method of the feeding system, polymerization system, and flash evaporation system; including:

[0034] (1) Connect the butadiene refining unit, solvent refining unit, and continuous polymerization aid unit to the bottom inlet of each polymerization reactor, and connect the flash evaporation system to the top outlet of each polymerization reactor to enter continuous polymerization mode; or

[0035] (2) Connect the butadiene refining unit and the solvent refining unit to the bottom feed port of each polymerization reactor, connect the batch polymerization aid unit to the top feed port of each polymerization reactor, and connect the flash evaporation system to the bottom discharge port of each polymerization reactor to enter the batch polymerization mode.

[0036] Preferably, in the continuous polymerization mode, the single-reactor capacity is 55,000-65,000 tons / year, and the microgel content is less than 0.01%; in the three-reactor parallel batch polymerization mode, the total production capacity of the equipment is 55,000-65,000 tons / year, and the microgel content is less than 0.1%.

[0037] This invention provides good production capacity in both continuous and intermittent polymerization modes, and expands the range of rubber grades by switching modes, thereby improving equipment compatibility and competitiveness.

[0038] Compared to common rubber types, low-cis-butadiene rubber has a relatively low microgel content and smaller gel particle size (approximately 100-300 nm), hence the term "microgel." The formation of microgels is complex, influenced by factors such as heat, oxygen, and radiation. To date, various polymerization processes (including bulk, solution, suspension, and emulsion) have produced microgels. The microgel content also varies with the polymerization process. Low-cis-butadiene rubber produced by batch polymerization typically has a microgel content of approximately 0.1% to 0.18%. Through the control and improvement of production equipment and polymerization processes in this invention, this has been reduced to less than 0.1%, preferably below 0.08%. The microgel content in continuous polymerization processes has been optimized from the usual approximately 0.015% to 0.05% to less than 0.01%, more preferably below 0.005%.

[0039] The advantages of this invention include at least the following:

[0040] (1) Based on the single-reactor continuous polymerization process and the single-reactor batch polymerization process, this invention designs material pipelines and equipment structures to realize the flexible switching between the continuous polymerization mode and the batch polymerization mode of low cis-cis-butadiene rubber. It utilizes the characteristics of high output and stable product performance of the continuous polymerization process, as well as the advantages of the variety and flexibility of the batch polymerization process, to provide production equipment with strong compatibility and low switching cost. Furthermore, it can be improved on the basis of existing equipment to further reduce the input cost.

[0041] (2) Equip the polymerization reactor with an efficient heat removal system, including but not limited to a special frame-anchor combined stirring structure and a jacketed cooler, so as to ensure the smooth operation of the two process modes before and after flexible switching, control the microgel content in the reactor, comprehensively reduce the cost of producing different grades of LCBR products, reduce the equipment required for production, and reduce the cost of production land.

[0042] (3) This invention achieves high production capacity while ensuring good heat removal effect by using parallel polymerization reactors and a high-efficiency heat removal system, thereby ensuring product quality. In the continuous polymerization mode, the single reactor production capacity can reach 55,000-65,000 tons / year, and in the intermittent polymerization mode, the capacity of three reactors in parallel can reach 55,000-65,000 tons / year. On this basis, the number of parallel polymerization reactors can be flexibly adjusted according to actual production capacity requirements, which has high capacity adjustment capability. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the flexible switching production equipment for low-cis-cis-butadiene rubber of the present invention.

[0044] Figure 2 This is a schematic diagram of the heat removal system of the present invention;

[0045] Figure 3 This is a top view of the anchor-type stirring paddle in the frame-anchor combined stirring structure of the present invention;

[0046] Figure 4 This is a front view of the anchor-type stirring paddle in the frame-anchor combined stirring structure of the present invention.

[0047] Figure labeling: 1-Butadiene refining unit; 11-Butadiene water washing tower; 12-Butadiene dehydration tower; 13-Butadiene de-heavy removal tower; 14, 15-Butadiene oil molecular sieve; 16-Mixer for refined butadiene and refined solvent; 17-Mixer for butadiene oil and scale inhibitor; 2-Solvent refining unit; 21-Solvent water washing tower; 22-Solvent dehydration tower; 23-Solvent de-heavy removal tower 1; 24-Solvent de-heavy removal tower 2; 25-Solvent residue tower; 3-Polymerization system; 311, 313, 315-Batch polymerization catalyst feed; 312, 314, 316-Batch polymerization coupling agent feed; 317-Feed preheater; 318-Feed precooler; 319-Continuous polymerization catalyst feed; 321-The... 322-Second polymerization reactor, 323-Third polymerization reactor, 320-Frame-anchor combined stirring structure, 3201-Rotating shaft, 3202-Frame-type stirring paddle, 3203-Anchor-type stirring paddle, 3204-Disturbance plate, 330-Jacketed cooler, 324-Flash solvent condenser, 325-Flash tank, 326-Flash tank dispensing pump, 327-Condensing solvent pump, 328-Terminator feed, 329-Antioxidant feed, 4-Coagulation system; 41-Final coagulation reactor, 42-Steam ejector, 43-Intermediate coagulation reactor, 44-First coagulation reactor, 45-Waste heat utilization system, 46-Cooler, 47-Tail gas condenser, 48-Tail gas compressor, 49-Oil-water separation tank. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. The objectives, features, and advantages of the exemplary embodiments disclosed in this invention will become readily apparent. Several embodiments are shown in the accompanying drawings by way of example and not limitation, and are not intended to limit or exhaustively describe the core solutions of this invention.

[0049] like Figure 1 The flexible switching production equipment for low-cis butadiene rubber shown includes a feeding system, a polymerization system 3, a flash evaporation system and a coagulation system 4 connected in sequence.

[0050] (1) Feeding system, specifically including:

[0051] (1.1) Butadiene refining unit 1, comprising in sequence: butadiene water washing tower 11, butadiene dehydration tower 12, butadiene de-weighting tower 13, refined butadiene and refined solvent mixer 16, butadiene oil molecular sieve (14, 15), butadiene oil and scale inhibitor mixer 17 (scale inhibitor inlet connected to said mixer), feed preheater 317, feed precooler 318;

[0052] (1.2) Solvent refining unit 2, which includes, in sequence: solvent washing tower 21, solvent dehydration tower 22, solvent deweighting tower 1 23 and solvent deweighting tower 24. The top discharge pipelines of solvent deweighting tower 1 23 and solvent deweighting tower 24 merge and then split into a first solvent discharge line and a second solvent discharge line. The first solvent discharge line is directly fed into the bottom feed port of each polymerization reactor. The second solvent discharge line is connected to the aforementioned refined butadiene and refined solvent mixer 16. In the mixer, part of the solvent is mixed with refined butadiene to form butadiene oil.

[0053] (1.3) Continuous polymerization aid unit, including continuous polymerization catalyst feed port 319, which is disconnectably connected to the aforementioned first solvent discharge line, and the catalyst and solvent are added together in continuous polymerization mode;

[0054] (1.4) Batch polymerization aid unit, including batch polymerization catalyst feed port (311, 313, 315) and batch polymerization coupling agent feed port (312, 314, 316). In batch mode, these feed ports for batch polymerization are set to feed the material to the feed port at the top of each polymerization reactor at a timed metering.

[0055] (2) The polymerization system 3 includes: a first polymerization reactor 321, a second polymerization reactor 322, and preferably a third polymerization reactor 323. Each reactor is provided with a feed port at the top and bottom. The top feed port is mainly connected to the feed port of the batch polymerization catalyst feeding device (311, 313, 315) and the feed port of the batch polymerization coupling agent feeding device (312, 314, 316). The bottom feed port is mainly used for the feeding of solvent and butane oil. They can be fed through the same feed port, but it is more preferable to feed through different feed ports to prevent the materials from reacting prematurely and clogging the feed port. In addition, each reactor is provided with a discharge port at the top and bottom. In the continuous polymerization mode, each reactor discharges through the top discharge port and is sent to the subsequent flash evaporation system. In the batch polymerization mode, each reactor discharges through the bottom discharge port and is sent to the subsequent flash evaporation system.

[0056] Each polymerization reactor has a volume of 28-35m³. 3 At least in the intermittent polymerization mode, the third polymerization reactor 323 is arranged in parallel with the first polymerization reactor 321 and the second polymerization reactor 322.

[0057] Each polymerization reactor has a frame-anchor combined stirring structure 320 and an optional jacketed cooler 330. The frame-anchor combined stirring structure 320 includes a rotating shaft 3201, several frame-type stirring paddles 3202 connected to the rotating shaft, and an anchor-type stirring paddle 3203 located at the bottom of the rotating shaft. The frame-type stirring paddles 3202 and the rotating shaft 3201 have a cooling water passage communicating with each other. The frame-type stirring paddles 3202 form several windows arranged side by side near the rotating shaft 3201. The total area of ​​the windows of the frame-type stirring paddles 3202 accounts for 50-90% of the total area of ​​the stirring paddles, and the outer diameter of the frame-type stirring paddles 3202 accounts for 70-90% of the inner diameter of the polymerization reactor. Preferably, at least some of the windows are provided with disturbance plates 3204, and more preferably, the disturbance plates 3204 of different windows have different inclination directions. The anchor-type stirring paddle 3203 is located at the bottom of the rotating shaft 3201. Since the anchor-type stirring paddle 3203 is close to the bottom of the polymerization reactor, it can effectively disturb the bottom layer of material and promote heat dissipation.

[0058] The jacketed cooler 330 includes a cooling water jacket covering the outer wall of the polymerization reactor, a cooling water inlet at the bottom of the jacket, and several cooling water outlets at the top of the jacket. Preferably, guide ribs or flow dividers are provided on the inner wall of the jacketed cooler to ensure that the cooling water is evenly distributed within the jacket and fully covers the polymerization reactor wall, thereby effectively removing heat from the reactor. Multiple outlets can be evenly distributed at the top of the jacket to ensure that the heated water can be discharged promptly, improving the cooling water circulation rate.

[0059] (3) Flash system, including: flash tank 325, flash solvent condenser 324, flash tank 325 dispensing pump, condensing solvent pump 327, terminator feed port 328, antioxidant feed port 329.

[0060] (4) Condensation system 4, including: a first condensation vessel 44, a second condensation vessel 43, and a final condensation vessel 41 connected in series. The first condensation vessel 44 is connected to the discharge line of the flash evaporation system, and the final condensation vessel 41 discharges the final product. The top reflux lines of the second condensation vessel 43 and the final condensation vessel 41 return to the bottom of the first condensation vessel 44 through the action of the steam ejector 42. The top reflux line of the first condensation vessel 44 is connected to the recovery system. Specifically, the top reflux line of the first condensation vessel 44 is connected in series to the waste heat utilization system 45, the cooler 46, and the oil-water separation tank 49. Then, the liquid phase oil is returned to the solvent refining unit 2. The gas phase material enters the tail gas condenser 47 and the tail gas compressor 48 from the oil-water separation tank 49, returns to the cooler 46, and then enters the oil-water separation tank 49 again.

[0061] This low-cis-butadiene rubber production equipment has equipment components and connection methods that provide both continuous polymerization mode and batch polymerization mode, and provides a flexible switching production method between continuous polymerization mode and batch polymerization mode by switching the connection method between the feeding system, polymerization system 3 and flash evaporation system.

[0062] The specific operation of the device to flexibly switch between continuous aggregation mode and intermittent aggregation mode is as follows:

[0063] (1) Switching from continuous aggregation mode to intermittent aggregation mode:

[0064] In continuous polymerization mode, the first polymerization reactor 321, the second polymerization reactor 322, and the optional third polymerization reactor 323 are arranged in parallel. The first solvent discharge line (connected to the continuous polymerization catalyst feed port 319) is connected to the bottom feed port B of each reactor. The solvent of the second solvent discharge line is mixed with refined butadiene to form butadiene oil. After the feed temperature is adjusted by the butadiene oil molecular sieve (14,15), the butadiene oil and scale inhibitor mixer 17, the feed preheater 317 and / or the feed precooler 318, it is connected to the bottom feed port A of each reactor to provide feed for continuous polymerization mode. After continuous polymerization in a single reactor, the material is discharged from the top of each polymerization reactor and then enters the flash evaporation system and the condensation system 4.

[0065] The specific process of continuous aggregation is as follows:

[0066] The first and second polymerization reactors 322 are arranged in parallel. Refined butadiene from the butadiene refining unit 1 and a portion of the refined solvent from the solvent refining unit 2 are mixed to form butadiene oil. After treatment with butadiene oil molecular sieves (14, 15), it is initially mixed with an anti-scaling agent and then statically mixed in the butadiene oil and anti-scaling agent mixer 17 to obtain butadiene oil raw material. After preheating or precooling to a suitable feed temperature, it enters the polymerization reactors from the bottom of the first and second polymerization reactors 322 respectively. Another portion of the solvent, after being mixed with the continuous polymerization catalyst, enters the first and second polymerization reactors 322 respectively. The polymer solution enters the polymerization reactor from the bottom of reactor 22. Under the combined action of additives, heat, and stirring, the polymerization reaction takes place. The solution then exits from the top of the first and second polymerization reactors 322. After entering the flash tank 325, flash evaporation occurs, and some of the solvent in the solution vaporizes. This vaporized solvent is then condensed into a liquid phase in the flash solvent condenser 324 for recovery, or it can be pumped to the flash solvent condenser 324 via the condensate pump 327 for recovery. The flash-evaporated solution, after adding a terminator and antioxidant, is sent to the coagulation system 4. In the coagulation reactor, the solvent is removed, and the purified solvent is recycled. The coagulated rubber granules are then sent to the post-processing unit for dehydration, drying, briquetting, and packaging before being shipped as rubber products.

[0067] In continuous polymerization mode, the single-reactor capacity is 55,000-65,000 tons / year, and the microgel content is less than 0.01%.

[0068] During the switchover, the material supply is stopped. After the material is discharged, the pipeline is connected and the feed is metered according to the connection method of the intermittent polymerization mode.

[0069] In batch polymerization mode, the first polymerization reactor 321, the second polymerization reactor 322, and the third polymerization reactor 323 are connected in parallel. Butyl oil and solvent are metered and fed into each reactor through the bottom feed ports A and B, respectively. The batch polymerization catalyst and the batch polymerization coupling agent are metered and fed into each reactor through the top feed ports, respectively, to complete the feeding of batch polymerization. The bottom discharge ports of each polymerization reactor are connected in sequence to the flash evaporation system and the condensation system 4.

[0070] The specific process of intermittent polymerization is as follows:

[0071] The first, second, and third polymerization reactors (321, 322, 323) are arranged in parallel. Refined butadiene from butadiene refining unit 1 and a portion of refined solvent from solvent refining unit 2 are mixed to form butadiene oil. After being treated by butadiene oil molecular sieves (14, 15), it is initially mixed with a scale inhibitor and then statically mixed in butadiene oil and scale inhibitor mixer 17 to obtain butadiene oil raw material. After being preheated or precooled to a suitable feed temperature, it enters the polymerization reactors (321, 322, 323) from the bottom, respectively. Another portion of the solvent enters the polymerization reactors (321, 322, 323) from the bottom, respectively. The batch polymerization catalyst and batch polymerization coupling agent are added quantitatively from the top feed ports of the first, second, and third polymerization reactors (321, 322, 323), respectively. The polymerization reaction is carried out under the combined effects of additives, heat, and stirring. After the reaction, the resulting polymer solution is discharged from the bottom of the first, second, and third polymerization reactors (321, 322, 323) into a flash evaporation system. The operation of the flash evaporation system is similar to that of the continuous polymerization mode. The polymer solution is then sent to a coagulation unit, where the solvent is removed. The removed solvent is refined and recycled. The coagulated polymer particles are sent to a post-processing unit for dehydration, drying, briquetting, and packaging before being shipped as rubber products. In the three-reactor parallel batch polymerization mode, the total production capacity is 55,000-65,000 tons / year, with a microgel content of less than 0.1%.

[0072] (2) Switching from intermittent polymerization mode to continuous polymerization mode: The specific operation of each mode is similar to the previous one, mainly involving the switching of the corresponding pipelines and the metering control of the corresponding materials.

[0073] Example 1

[0074] Production of low-cis-cis butadiene rubber using a single-reactor continuous polymerization method includes:

[0075] Using a volume of 30m 3The first and second polymerization reactors are connected in parallel for single-reactor continuous polymerization experiments. Both the first and second polymerization reactors are equipped with a frame-anchor combined stirring structure, including a rotating shaft, a frame-type stirring paddle connected to the rotating shaft, and an anchor-type stirring paddle located at the bottom of the rotating shaft. The frame-type stirring paddle and the anchor-type stirring paddle have a cooling water passage communicating with the rotating shaft. The frame-type stirring paddle has six parallel windows on each side near the rotating shaft, with the total area of ​​the windows accounting for approximately 75% of the total area of ​​the stirring paddle. The outer diameter of the frame-type stirring paddle accounts for approximately 85% of the inner diameter of the polymerization reactor.

[0076] The first and second polymerization reactors are also equipped with jacketed coolers, including a cooling water jacket covering the outer wall of the polymerization reactor, a cooling water inlet at the bottom of the cooling water jacket, and several cooling water outlets at the top of the cooling water jacket, so that the water that has been heated by heat transfer can be discharged in time, thereby improving the cooling water circulation rate.

[0077] Refined butadiene from the butadiene refining unit and a portion of the refined solvent from the solvent refining unit are mixed to form butadiene oil. After butadiene oil molecular sieve treatment, it is initially mixed with a scale inhibitor and then statically mixed in a butadiene oil and scale inhibitor mixer to obtain butadiene oil raw material. After preheating or precooling to a suitable feed temperature, it enters the polymerization reactor from the bottom of the first and second polymerization reactors, respectively. Another portion of the solvent, after being mixed with the continuous polymerization catalyst, enters the polymerization reactor from the bottom of the first and second polymerization reactors, respectively. The polymerization reaction begins, and the products are discharged from the top of the first and second polymerization reactors, respectively. The glue solution enters the flash tank for flash evaporation. After adding a terminator and antioxidant, the flash-evaporated glue solution is sent to the coagulation system. The solvent is removed from the glue solution in the coagulation tank, and the removed solvent is refined and recycled. The coagulated glue particles are sent to the post-treatment unit for dehydration, drying, and briquetting.

[0078] The process conditions for single-reactor continuous polymerization include:

[0079] The feed temperature is controlled at 5±1℃. Refined butadiene and a portion of the solvent are first mixed to obtain butadiene oil. The butadiene oil feed rate is 22-24 t / h (where the mass ratio of refined butadiene to refined solvent is approximately 1:5, and the scale inhibitor dosage is 400-600 ppm). The catalyst feed rate is 15-20 kg / h. The temperature inside the polymerization reactor is controlled at 100-120℃, the pressure is controlled at 0.8-1.0 MPa, the terminator dosage is 300-400 ppm, and the antioxidant dosage is 0.1-0.2%. The gel content of the product is approximately 0.003-0.005%, and the gel particle size is approximately 150±10 nm. Based on production calculations, the single-reactor capacity under continuous polymerization mode can reach approximately 60,000 tons / year.

[0080] Example 2

[0081] Production of low-cis-cis butadiene rubber using a single-reactor batch polymerization method includes:

[0082] Using a volume of 30m 3 The first and second polymerization reactors were set up in parallel for batch polymerization experiments (the reactor structure was the same as in Example 1). Refined butadiene from the butadiene refining unit and a portion of the refined solvent from the solvent refining unit were mixed to form butadiene oil. After being treated with butadiene oil molecular sieves, it was initially mixed with a scale inhibitor and then statically mixed in a butadiene oil and scale inhibitor mixer to obtain butadiene oil raw material (where the mass ratio of refined butadiene to refined solvent was approximately 1:5, and the scale inhibitor dosage was 400-600 ppm). After being preheated or precooled to a suitable feed temperature, it entered the polymerization reactors from the bottom of the first and second polymerization reactors respectively. Another portion of the solvent entered the polymerization reactors from the bottom of the first and second polymerization reactors respectively. The batch polymerization catalyst and batch polymerization coupling agent were quantitatively added from the top feed ports of the first and second polymerization reactors respectively. The polymerization reaction was carried out under the combined effects of additives, heat, and stirring. After the reaction is complete, the resulting rubber solution is discharged from the bottom of the first and second polymerization reactors into the flash evaporation system. The operation of the flash evaporation system is similar to that of the continuous polymerization mode. The rubber solution is then sent to the coagulation unit, where the solvent is removed from the rubber solution. The removed solvent is purified and recycled. The coagulated rubber particles are sent to the post-processing unit for dehydration, drying, briquetting, and packaging before being shipped as rubber products.

[0083] The process conditions for batch polymerization are shown in Table 1:

[0084] Table 1

[0085]

[0086] The gel content of the detected product was approximately 0.06-0.08%, and the gel particle size was approximately 220±20 nm.

[0087] Based on production volume calculations, the combined capacity of the first and second polymerization reactors under this model is approximately 42,000 tons per year.

[0088] Example 3

[0089] Production of low-cis-cis butadiene rubber using a single-reactor continuous polymerization method includes:

[0090] Using a volume of 30m 3 The first and second polymerization reactors are connected in parallel for single-reactor continuous polymerization experiments. Both the first and second polymerization reactors are equipped with a frame-anchor combined stirring structure, including a rotating shaft, a frame-type stirring paddle connected to the rotating shaft, and an anchor-type stirring paddle located at the bottom of the rotating shaft. The frame-type stirring paddle and the anchor-type stirring paddle have a cooling water passage communicating with the rotating shaft. The frame-type stirring paddle has six parallel windows on each side near the rotating shaft, with the total area of ​​the windows accounting for approximately 85% of the total area of ​​the stirring paddle. The outer diameter of the frame-type stirring paddle accounts for approximately 90% of the inner diameter of the polymerization reactor. Some windows contain disturbance plates; the tilt direction of the disturbance plates varies in different frame-type stirring paddles (see Appendix). Figure 2Vertical and horizontal disturbance plates are installed in the empty windows of the same row to increase material disturbance and improve heat removal efficiency.

[0091] The first and second polymerization reactors are each equipped with a jacketed cooler, including a cooling water jacket covering the outer wall of the polymerization reactor, a cooling water inlet at the bottom of the cooling water jacket, and several cooling water outlets at the top of the cooling water jacket. This allows the water that has been heated by heat transfer to be discharged in a timely manner, improving the cooling water circulation rate. Furthermore, guide ribs or flow dividers are provided on the inner wall of the jacketed cooler, ensuring that the cooling water is evenly distributed within the jacket and fully covers the polymerization reactor wall, thereby effectively removing heat from the polymerization reactor.

[0092] Refined butadiene from the butadiene refining unit and a portion of the refined solvent from the solvent refining unit are mixed to form butadiene oil. After butadiene oil molecular sieve treatment, it is initially mixed with a scale inhibitor and then statically mixed in a butadiene oil and scale inhibitor mixer to obtain butadiene oil raw material. After preheating or precooling to a suitable feed temperature, it enters the polymerization reactor from the bottom of the first and second polymerization reactors, respectively. Another portion of the solvent, after being mixed with the continuous polymerization catalyst, enters the polymerization reactor from the bottom of the first and second polymerization reactors, respectively. The polymerization reaction begins, and the products are discharged from the top of the first and second polymerization reactors, respectively. The glue solution enters the flash tank for flash evaporation. After adding a terminator and antioxidant, the flash-evaporated glue solution is sent to the coagulation system. The solvent is removed from the glue solution in the coagulation tank, and the removed solvent is refined and recycled. The coagulated glue particles are sent to the post-treatment unit for dehydration, drying, and briquetting.

[0093] The process conditions for single-reactor continuous polymerization include:

[0094] The feed temperature is controlled at 5±1℃. Refined butadiene and a portion of the solvent are first mixed to obtain butadiene oil. The butadiene oil feed rate is 22-25 t / h (where the mass ratio of refined butadiene to refined solvent is 1:5, and the scale inhibitor dosage is 300-600 ppm). The catalyst feed rate is 16-20 kg / h. The temperature inside the polymerization reactor is controlled at 100-120℃, and the pressure is controlled at 0.8-1 MPa. The gel content of the product is approximately 0.001-0.003%, and the gel particle size is approximately 120±10 nm. Based on the production volume calculation, the single-reactor capacity of continuous polymerization can reach approximately 62,000 tons / year.

[0095] Example 4

[0096] Production of low-cis-cis-butadiene rubber using a batch polymerization method includes:

[0097] Volume 30m 3The first, second, and third polymerization reactors were connected in parallel for batch polymerization experiments (the reactor structure was the same as in Example 3), and the material dosage and process conditions were the same as in Example 2. Refined butadiene from the butadiene refining unit and a portion of the refined solvent from the solvent refining unit were mixed to form butadiene oil. After treatment with butadiene oil molecular sieves, it was initially mixed with a scale inhibitor and then statically mixed in a butadiene oil and scale inhibitor mixer to obtain butadiene oil raw material. After preheating or precooling to a suitable feed temperature, it entered the polymerization reactors from the bottom of the first, second, and third polymerization reactors, respectively. Another portion of the solvent entered the polymerization reactors from the bottom of the first, second, and third polymerization reactors, respectively. The batch polymerization catalyst and batch polymerization coupling agent were quantitatively added from the top feed port of the first polymerization reactor. The polymerization reaction was carried out under the combined effects of additives, heat, and stirring. After the reaction, the resulting gel was discharged from the bottom of the first, second, and third polymerization reactors to a flash evaporation system. The operation of the flash evaporation system was similar to that of the continuous polymerization mode. The gel was then sent to a coagulation unit to remove the solvent from the gel. The removed solvent was refined and recycled. The coagulated rubber particles are sent to the post-processing unit for dehydration, drying, briquetting, and packaging before being shipped as rubber products.

[0098] The gel content of the detected product was approximately 0.05-0.07%, and the gel particle size was approximately 200±20 nm.

[0099] Based on production volume, the total capacity of the three reactors under this model is approximately 64,000 tons per year.

[0100] The production equipment and process of this invention, by switching the connection methods between systems such as the feeding system, polymerization system, and flash evaporation system, and by providing an efficient heat removal system, can flexibly switch between single-reactor continuous polymerization mode and batch polymerization mode for low cis-butadiene rubber. The synergistic effect of multiple improvement links enables flexible switching between the two polymerization modes on the same production line, achieving the goal of producing low cis-butadiene rubber with stable quality and a variety of grades, and adjustable production capacity. Furthermore, the investment in modification based on existing equipment is relatively small, with good compatibility and low energy consumption in the production process.

[0101] The preferred embodiments of the present invention have been described above to make the spirit of the present invention clearer and easier to understand, and are not intended to limit the present invention. All modifications, substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope summarized by the appended claims.

Claims

1. A flexible switching production equipment for low-cis butadiene rubber, characterized in that, It includes a feeding system, a polymerization system, a flash evaporation system, and a condensation system connected in sequence; The feeding system includes a butadiene refining unit, a solvent refining unit, a continuous polymerization aid unit for continuous polymerization mode, and a batch polymerization aid unit for batch polymerization mode; The polymerization system includes at least a first polymerization reactor and a second polymerization reactor arranged in parallel; The production equipment can flexibly switch between continuous polymerization mode and intermittent polymerization mode: The continuous polymerization mode includes: a butadiene refining unit, a solvent refining unit, and a continuous polymerization aid unit, which are respectively connected to the bottom inlet of each polymerization reactor, and a flash evaporation system, which is respectively connected to the top outlet of each polymerization reactor; The batch polymerization mode includes: a butadiene refining unit and a solvent refining unit connected to the bottom inlet of each polymerization reactor, a batch polymerization aid unit connected to the top inlet of each polymerization reactor, and a flash evaporation system connected to the bottom outlet of each polymerization reactor.

2. The production equipment as described in claim 1, characterized in that, The solvent refining unit has a first solvent discharge line and a second solvent discharge line, and the first solvent discharge line is connected to the bottom inlet of each polymerization reactor. The second solvent discharge line and the discharge line of the butadiene refining unit are both connected to the butadiene oil mixer to mix them into butadiene oil. The outlet of the butadiene oil mixer is connected to the bottom feed port of each polymerization reactor. Downstream of the butyl oil mixer outlet, there are also butyl oil molecular sieves, as well as a feed preheater and / or a feed precooler.

3. The production equipment as described in claim 1, characterized in that, The continuous polymerization aid unit includes a continuous polymerization catalyst feed port; The batch polymerization aid unit includes a batch polymerization catalyst feed port and a batch polymerization coupling agent feed port.

4. The production equipment as described in any one of claims 1-3, characterized in that, It also includes a third polymerization reactor, each with a volume of 28-35m³. 3 At least in the intermittent polymerization mode, the third polymerization reactor is arranged in parallel with the first and second polymerization reactors.

5. The production equipment as described in claim 4, characterized in that, Each polymerization reactor has a frame-anchor combined stirring structure, which includes a rotating shaft, a frame-type stirring paddle connected to the rotating shaft, and an anchor-type stirring paddle located at the bottom of the rotating shaft.

6. The production equipment as described in claim 5, characterized in that, The frame-type agitator forms several parallel windows near its rotation axis, with the total area of ​​the windows accounting for 50-90% of the total area of ​​the frame-type agitator, and the outer diameter of the frame-type agitator accounting for 70-90% of the inner diameter of the polymerization reactor.

7. The production equipment as described in claim 6, characterized in that, The window is equipped with a disturbance plate; there are at least two windows, and the disturbance plates of the different windows are tilted in different directions.

8. The production equipment as described in any one of claims 5-7, characterized in that, The frame-type agitator, the anchor-type agitator, and the rotating shaft have a connected cooling water passage.

9. A flexible switching production method for low-cis-cis-butadiene rubber, utilizing the flexible switching production equipment for low-cis-cis-butadiene rubber as described in any one of claims 1-8, characterized in that, The production method flexibly switches between continuous polymerization and batch polymerization modes by changing the connection method of the feeding system, polymerization system, and flash evaporation system; including: Continuous polymerization: The butadiene refining unit, solvent refining unit, and continuous polymerization aid unit are connected to the bottom inlets of each polymerization reactor, and the flash evaporation system is connected to the top outlet of each polymerization reactor, thus entering continuous polymerization mode; or Batch polymerization: Connect the butadiene refining unit and solvent refining unit to the bottom feed port of each polymerization reactor, connect the batch polymerization aid unit to the top feed port of each polymerization reactor, and connect the flash evaporation system to the bottom discharge port of each polymerization reactor to enter the batch polymerization mode.

10. The production method as described in claim 9, characterized in that, In continuous polymerization mode, the single-reactor capacity is 55,000-65,000 tons / year, and the microgel content is less than 0.01%; in the three-reactor parallel batch polymerization mode, the total production capacity of the equipment is 55,000-65,000 tons / year, and the microgel content is less than 0.1%.

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