Pre-flash energy-saving method for condensation system of SSBR (Solid Sequence Biofilm Reactor) production device

Abstract

The invention provides a pre-flash evaporation energy-saving method for a condensation system of an SSBR production device. The condensation system comprises a pre-flash evaporation tank, a glue solution preheater, an oil cooler, a vacuum pump, a glue solution feeding pump and a condensation kettle. The pre-flash energy-saving method comprises the following steps: S10, preheating a glue solution from a polymerization system to a set temperature through a glue solution preheater; s20, the preheated glue solution is fed into a pre-flash tank, a gas-phase solvent at the top of the pre-flash tank is sucked out through a vacuum pump, and the glue solution at the bottom of the pre-flash tank is fed into a condensation kettle through a glue solution feeding pump; wherein the gas-phase solvent sucked out by the vacuum pump enters the glue solution preheater for primary heat exchange, and then enters the oil cooler for secondary heat exchange, so that the steam waste heat of the gas-phase solvent is recovered. Volatile components are separated out in a rapid decompression vaporization mode before materials enter main equipment of a condensation system, and due to the fact that steam in the device does not need to be additionally consumed in the process, energy consumption of the device can be remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solution polymer preparation, and more particularly, to a pre-flash evaporation energy-saving method for the coagulation system of an SSBR production device. Background Art

[0002] Solution styrene-butadiene rubber (SSBR) is a rubber copolymerized from styrene and butadiene, which has excellent abrasion resistance, cold resistance, low heat build-up, low shrinkage, good color and other characteristics, and is widely used in fields such as tires, shoe materials, and industrial parts. Its production process is usually divided into batch polymerization and continuous polymerization. The latter has high production efficiency, low energy consumption, and stable product quality. The SSBR production device includes a refining unit, a polymerization unit, a blending unit, a coagulation unit, a post-treatment unit, etc. Among them, the coagulation section plays a crucial role in improving the product purity and quality.

[0003] However, there are several problems in the existing coagulation process: First, during the coagulation process, fluctuations in the operating conditions of the polymerization kettle will cause excessive moisture in the gas phase, resulting in solvent-containing wastewater, affecting the subsequent sewage treatment and increasing costs; Second, the steam heating method leads to high steam consumption and high operating costs; Finally, too high a stirring intensity may cause the rubber particles to break, generating a large number of fine rubber particles, resulting in an increased loss rate and increasing the risk of system blockage. These problems limit the production efficiency and lead to an increase in energy consumption and operating costs.

[0004] Although some technologies have been improved, such as improving the oil-water separation efficiency and improving the steam injection control, the effects are limited, and the main problems existing in the coagulation process have not been effectively solved. Moreover, some improvement schemes consume a large amount of heat, and the energy-saving effect is not obvious. Summary of the Invention

[0005] The present invention aims to provide a pre-flash evaporation energy-saving method for the coagulation system of an SSBR production device. By separating volatile components in a rapid pressure reduction and vaporization manner before the material enters the main equipment of the coagulation unit, the load of the subsequent process can be reduced or the operating conditions can be optimized. Since this process does not require additional steam consumption within the device, it can significantly reduce the energy consumption of the device and can also reduce wastewater discharge.

[0006] To achieve the above object, the present invention provides an energy-saving method for pre-flash evaporation of a coagulation system in an SSBR production device. The coagulation system includes a pre-flash evaporation tank, a rubber solution preheater, an oil cooler, a vacuum pump, a rubber solution feed pump, and a coagulation kettle. The energy-saving method for pre-flash evaporation includes the following steps: S10. Preheat the rubber solution from the polymerization system to a set temperature through the rubber solution preheater; S20. Feed the preheated rubber solution into the pre-flash evaporation tank. The gas-phase solvent at the top of the pre-flash evaporation tank is sucked out by the vacuum pump, and the rubber solution at the bottom of the pre-flash evaporation tank is sent to the coagulation kettle through the rubber solution feed pump. Among them, the gas-phase solvent sucked out by the vacuum pump enters the rubber solution preheater for primary heat exchange, and then enters the oil cooler for secondary heat exchange to recover the steam waste heat of the gas-phase solvent.

[0007] Further, in S20, the gas-phase solvent at the top of the pre-flash evaporation tank is sucked out by the vacuum pump, so that the pressure in the pre-flash evaporation tank is maintained at a slightly negative pressure. Among them, the pressure range of the slightly negative pressure is from -0.08 MPa to 0.01 MPa.

[0008] Further, in S20, the rubber solution at the bottom of the pre-flash evaporation tank is sent to a static mixer through the rubber solution feed pump and mixed with a dispersant, and then sent to the coagulation kettle. Among them, the dispersant includes sodium polycarboxylate, sodium oleate, or sodium stearate.

[0009] Further, after the gas-phase solvent undergoes secondary heat exchange in the oil cooler, the condensed liquid-phase solvent flows into the solvent buffer tank, and the non-condensable gas in the oil cooler is introduced into the tail gas collection system.

[0010] Further, the flashing amount of the rubber solution at the bottom of the pre-flash evaporation tank is controlled within 65% - 80%.

[0011] Further, the set temperature for preheating the rubber solution in the rubber solution preheater is 80°C - 100°C.

[0012] Further, the residence time of the rubber solution in the pre-flash evaporation tank is ≥ 120 seconds.

[0013] Further, the coagulation system is provided with a temperature-pressure cascade control system for synchronously adjusting the outlet temperature of the rubber solution preheater when adjusting the pressure of the pre-flash evaporation tank. Among them, the temperature-pressure cascade control system includes a main loop and a secondary loop. The main loop is used to control the pressure of the pre-flash evaporation tank, and the secondary loop is used to control the outlet temperature of the rubber solution preheater.

[0014] Further, the preheater includes a first temperature transmitter and a gas-phase solvent outlet regulating valve; the pre-flash evaporation tank includes a pressure transmitter, a pressure regulating valve, a flow meter, a feed regulating valve, and a liquid level gauge; the oil cooler includes a second temperature transmitter and a return water flow regulating valve.

[0015] Furthermore, a logic interlock control is formed between the first temperature transmitter and the gas-phase solvent outlet regulating valve; a logic interlock control is formed between the pressure transmitter, the pressure regulating valve, and the vacuum pump; a logic interlock control is formed between the flowmeter, the feed regulating valve, and the vacuum pump; a logic interlock control is formed between the liquid level gauge and the glue feed pump; a logic interlock control is formed between the second temperature transmitter and the return water flow regulating valve.

[0016] After adopting the technical solution of the present invention, the following technical effects can be achieved: (1) Improve the solvent removal efficiency and reduce the subsequent process load: Through rapid decompression vaporization, this process can efficiently separate 65%-80% of the solvent in the glue liquid, significantly reducing the steam stripping load of the subsequent coagulation kettle. It is expected to directly reduce the steam consumption by 30%-50% and directly reduce the energy consumption cost. At the same time, the viscosity of the glue liquid after pre-flash evaporation is controllable, reducing the excessive mass transfer resistance caused by too high viscosity inside the coagulation kettle and further shortening the reaction time. This process uses a vacuum pump to assist flash evaporation, reducing heat energy consumption by 30%-50% compared with traditional steam stripping. The frequency conversion control and the waste heat recovery of the flash vapor-phase solvent further reduce the power consumption by 10%-20%. Using the operating condition of slightly negative pressure can increase the flash evaporation speed by 20%-40% and the solvent residue is lower.

[0017] (2) Energy conservation, consumption reduction, and resource cycle optimization: The solvent vapor separated after pre-flash evaporation can be efficiently recovered after condensation and directly used in the polymerization section after refining, forming a virtuous cycle. At the same time, the COD content in the wastewater can be significantly reduced, reducing the load on the backend sewage treatment unit.

[0018] (3) Improve product quality and process stability: Through precise control of temperature, pressure, and residence time, the pre-flash evaporation process can avoid the thermal degradation of rubber and ensure the stability of key indicators such as the Mooney viscosity and molecular weight distribution of the product. At the same time, the rapid removal of solvents and oligomers reduces the risk of self-polymerization of residual monomers in the rubber phase and improves the product purity. It is expected that the ash content of SSBR can be reduced to less than 0.05%, meeting the requirements of high-end high-performance tires.

[0019] (4) Enhance production safety and equipment service life: By removing most of the solvents at the front end, the pre-flash evaporation process significantly reduces the explosion risk of the coagulation unit. The operating conditions of the pre-flash evaporation tank are milder than those of the coagulation kettle, reducing the rates of equipment coking and corrosion, extending the service life of the equipment, and reducing maintenance costs.

[0020] (5) Promote green manufacturing and low-carbon transformation: The pre-flash evaporation process directly reduces the carbon emission intensity of the device by reducing steam consumption and solvent emissions. Description of the Drawings

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which: Figure 1 It is a schematic structural diagram provided for Embodiment 1 of the present invention.

[0022] Explanation of reference numerals: 1 - Glue solution preheater; 2 - Oil cooler; 3 - Oil-gas condenser; 4 - Static mixer; 5 - Pre-flash tank; 6 - First kettle; 7 - Middle kettle; 8 - Last kettle; 9 - Oil-water separation tank; 10 - Solvent buffer tank; 11 - Vacuum pump; 12 - Glue solution feed pump; 13 - First kettle rubber particle water pump; 14 - Middle kettle rubber particle water pump; 15 - Last kettle rubber particle water pump; 16 - Stratification water pump; 17 - Solvent external delivery pump; 18 - Steam jet pump; 19 - Reactant feed port; 20 - Hot water feed port; 21 - Dispersant feed port; 22 - Glue solution discharge port; 23 - Wet solvent discharge port. Specific embodiments

[0023] To make the above objects, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] Solution-polymerized styrene-butadiene rubber (SSBR) is a rubber-like elastomer prepared by copolymerizing styrene and butadiene, and has characteristics such as wear resistance, cold resistance, low heat generation, low shrinkage, good color, less ash content, high purity, and fast vulcanization speed. Its polymerization process is mainly divided into batch polymerization and continuous polymerization. Among them, the continuous polymerization process has high production efficiency, low energy consumption, and stable product quality. SSBR is widely used in the tire industry, especially in high-performance tires such as green tires and anti-skid tires, and is also widely used in fields such as shoe materials, industrial parts, clothing, plastic modification, and adhesives. Due to its excellent comprehensive performance, SSBR has become one of the new synthetic rubber varieties that are intensively studied, developed, and produced around the world.

[0025] The production device of SSBR mainly consists of a tank area, a refining unit (including butadiene, styrene, and solvent refining), an auxiliary agent preparation and polymerization unit, a blending unit, a coagulation unit, a post-treatment unit, and public auxiliary facilities. The refined butadiene, styrene monomer, solvent oil, and initiator are sent into the polymerization kettle in a certain proportion for polymerization reaction. The generated glue solution is pumped to the blending tank area for blending, and then sent into the coagulation kettle for coagulation. During the coagulation process, the solvent is evaporated and separated, and then the glue solution enters the post-treatment process for dehydration and drying, and finally is metered and packaged and stored as a finished product.

[0026] In the production process of solution styrene-butadiene rubber, the coagulation section is a key step. The coagulation process usually occurs in a series consisting of three coagulation kettles. After the rubber solution generated by the polymerization unit is mixed with the dispersant in proportion, it enters the first kettle of the coagulation kettle. Under the action of stirring and steam, the rubber solution, hot water and steam are fully mixed in the first kettle, and the solvent, butadiene and part of the water are removed in the gas phase. The rubber particle water at the bottom of the first kettle is pumped into the middle and last coagulation kettles, and steam is introduced into these kettles for heating to further recover the solvent in the rubber solution. The gas-phase solvent at the top of the coagulation kettle is collected through a pipeline, enters the oil-gas condenser for condensation, and then flows into the oil-water separation tank to recover the solvent. The recovered crude solvent is treated by the refining unit and then recycled. The rubber particle water in the last kettle is sent to the post-treatment unit for further dehydration and drying to ensure that the moisture in the rubber particles is fully removed, thereby obtaining a dry solution styrene-butadiene rubber product.

[0027] The main function of the coagulation unit is to remove impurities such as unreacted raw materials and oligomers through separation and purification, thereby improving the purity and quality of the product. The operating conditions (such as temperature and pressure) in the coagulation kettle will directly affect the crystallization and hardness of the rubber particles; while the type and dosage of the dispersant will affect the dispersibility and stability of the rubber particles. Therefore, the coagulation unit plays a crucial role in the production of solution styrene-butadiene rubber, not only affecting the purity and quality of the product, but also directly affecting the physical properties, processing properties and application properties of the product. Therefore, in the production process of solution styrene-butadiene rubber, great attention must be paid to the design and operation management of the coagulation unit to ensure that the product quality and performance meet the requirements.

[0028] However, the existing coagulation process flow has the following main defects: (1) During the coagulation process, due to the fluctuations in the operating conditions of the polymerization kettle, it is easy to cause excessive moisture in the gas phase of the coagulation kettle, and then a large amount of wastewater containing solvent is generated. The oil content of these wastewaters is relatively high, which not only seriously affects the water quality and load of the backend sewage treatment unit, increases the treatment cost, but also leads to excessive solvent emissions, causing waste of raw materials, thereby increasing the production cost. (2) The coagulation unit heats by introducing steam into the coagulation kettle to remove the solvent, unreacted raw materials and oligomers in the rubber solution, but due to the large steam consumption, the operating cost is high. (3) During the coagulation process, the temperature cannot be accurately controlled, which is easy to cause the rubber solution to overheat, and then cause thermal degradation of the rubber molecular chain, affecting the product quality. (4) Due to the low viscosity of the rubber solution, too large a stirring intensity or too fast a rotation speed will generate too large a shear force, resulting in the fragmentation of the rubber particles. This not only affects the product quality, but also may cause system blockage, resulting in unplanned shutdowns and frequent repairs.

[0029] The production efficiency of the coagulation section directly affects the production capacity and benefits of the solution styrene-butadiene rubber production line. Due to the existence of the above problems, the production efficiency is usually limited. At the same time, in order to maintain the coagulation effect and handle problems such as wastewater and wet spot rubber, the overall energy consumption and operating costs increase, resulting in a decline in product profit margins.

[0030] Furthermore, there are the following deficiencies in the improvement of the previous process technology: (1) Regarding the problem of solvent entrainment in the wastewater of the coagulation unit, the oil-water separation efficiency was improved by modifying the equipment (such as the oil-water separation tank) to reduce the proportion of the oil phase entering the water phase. However, due to the incomplete separation effect, this measure has limited impact on reducing the oil content in the wastewater. (2) Regarding the problem of excessive steam consumption in the coagulation unit, the steam injection amount was adjusted by modifying the steam injection pump and adopting advanced control technology to reduce energy consumption. However, the procurement cost of this equipment and system is relatively high, the operation flexibility is small, and there is a lag in the control reaction. If the process conditions fluctuate frequently, the treatment effect of the coagulation section cannot be guaranteed, and a large amount of waste rubber may be generated, increasing the proportion of defective products. (3) In order to maintain the treatment effect and reduce problems such as wet spot rubber and broken rubber, it is often necessary to increase the dosage of the dispersant. This not only increases the production cost, but also increases the labor intensity of workers when there is too much dispersant. (4) Patent CN104072643A proposed a scheme of atmospheric flash evaporation after heating up, but its flash evaporation effect is poor, and the removal efficiency is only 20 - 60 wt%. In addition, this scheme requires the feed rubber solution to be heated to 130 °C using an external heat source, consuming a large amount of heat, and the energy-saving effect is not obvious. At the same time, there is a steam pipeline at the bottom of the flash evaporation tank, relying on steam-assisted stripping, and the reduction of steam consumption is limited.

[0031] Through these analyses, it can be seen that although the improvement of the existing technology alleviates the problems to a certain extent, there are still defects such as low efficiency, high energy consumption, and high cost, which need to be further optimized and improved.

[0032] An embodiment of the present invention provides a pre-flash evaporation energy-saving method for the coagulation system of an SSBR production device. The coagulation system includes a pre-flash evaporation tank, a rubber solution preheater, an oil cooler, a vacuum pump, a rubber solution feed pump, and a coagulation kettle; the pre-flash evaporation energy-saving method includes the following steps: S10. Preheat the rubber solution from the polymerization system to a set temperature through the rubber solution preheater; S20. Feed the preheated rubber solution into the pre-flash evaporation tank, and the gas-phase solvent at the top of the pre-flash evaporation tank is sucked out by the vacuum pump, and the rubber solution at the bottom of the pre-flash evaporation tank is sent to the coagulation kettle through the rubber solution feed pump; wherein, the gas-phase solvent sucked out by the vacuum pump enters the rubber solution preheater for primary heat exchange, and then enters the oil cooler for secondary heat exchange to recover the steam waste heat of the gas-phase solvent.

[0033] The present invention relates to a pre-flash evaporation energy-saving method for the coagulation system in an SSBR (styrene-butadiene rubber) production device. By utilizing waste heat recovery technology, energy consumption is reduced during the production process, and the energy utilization efficiency is improved. Specifically, the rubber solution preheater heats the rubber solution to a predetermined temperature, reducing the energy demand in subsequent processes; while the pre-flash evaporation tank is used to separate the solvent and colloid in the rubber solution through partial evaporation for subsequent treatment. The gas-phase solvent at the top of the pre-flash evaporation tank is extracted by a vacuum pump and guided for recovery. After the steam waste heat of the gas-phase solvent is recovered, it is used to preheat the rubber solution. This not only reduces waste heat emissions but also reduces the consumption of external energy by using the recovered heat. On the one hand, the gas-phase solvent exchanges heat with the incoming cold rubber solution in the rubber solution preheater to increase the temperature of the rubber solution; on the other hand, the preheated gas-phase solvent enters the oil cooler for further heat exchange, thereby more efficiently recovering heat and improving the overall thermal energy utilization efficiency of the system.

[0034] Specifically, the process flow of the rubber solution pre-flash evaporation process in the coagulation system disclosed in the present invention is described as follows: The rubber solution from the polymerization system first passes through the rubber solution preheater to be heated to the set temperature. The heat source of the rubber solution preheater is the gas-phase solvent after flash evaporation (≥90°C), which reduces the viscosity and promotes flash evaporation. The control range of the preheating temperature is 80°C - 100°C. Since the SSBR process of solution-polymerized styrene-butadiene rubber uses solution polymerization and the solvents selected are cyclohexane and n-hexane, pressure needs to be maintained during preheating to improve the flash evaporation efficiency. Compared with the prior art where external steam heat sources are used for heating, using the gas-phase steam after flash evaporation for preheating in the present invention can increase the energy utilization rate, effectively reduce the circulating water consumption and preheating steam volume of the backend oil cooler, thereby reducing the overall energy consumption of the device.

[0035] The preheated rubber solution enters the pre-flash evaporation tank through the feed regulating valve. A vacuum pump is used in the pre-flash evaporation tank to timely extract the gas phase in the tank, maintaining the pressure in the tank at a slightly negative pressure to enhance the flash evaporation effect. The operating pressure control range of the pre-flash evaporation tank is -0.08 MPa to 0.01 MPa. Compared with the atmospheric pressure flash evaporation process in the prior art, the pre-flash evaporation tank in this process is in a high-temperature and negative-pressure environment, and the flash evaporation effect and efficiency of the solvent will be greatly enhanced. At the same time, no steam pipeline is introduced at the bottom of the flash evaporation tank in this process, reducing the risk of steam leakage and increasing the purity of the flash evaporation solvent. The present invention utilizes the pressure reduction effect of the material when passing through the regulating valve, and adds a pre-flash evaporation tank after the regulating valve to pre-flash the material. By optimizing the solvent removal process, the production efficiency, energy utilization rate, and product quality are significantly improved, which has far-reaching significance for the economy and sustainability of chemical production.

[0036] Furthermore, the core principle of vacuum pump-assisted flash evaporation is to reduce the pressure in the flash tank, enabling the solvent to evaporate rapidly at a lower temperature and reducing the dependence on external heat sources. The vacuum pump is the main energy-consuming equipment. The selected vacuum pump for this process is a three-stage variable-frequency Roots vacuum pump. Equipped with a variable-frequency function, it can reduce the ineffective operation time of the vacuum pump and lower the power consumption. At the same time, based on the pressure transmitter and pressure regulating valve of the pre-flash tank, the vacuum degree inside the tank can be adjusted in real time to avoid energy consumption waste caused by over-evacuation. Meanwhile, it is logically interlocked with the feed regulating valve and feed flowmeter to optimize the opening of the feed regulating valve in real time through the vacuum degree, control the feed flow rate of the material, reduce the flow resistance, and lower the load of the vacuum pump.

[0037] In the tank, the solvent and low-boiling volatile substances such as oligomers in the glue liquid vaporize rapidly and are separated from the glue liquid. The gaseous solvent at the top of the pre-flash tank is sucked out by the vacuum pump and enters the glue liquid preheater for primary heat exchange with the incoming glue liquid. After the heat exchange, the gaseous solvent enters the oil cooler for secondary heat exchange. The condensed crude solvent condensate flows into the solvent buffer tank in the device by gravity and is then sent to the refining unit for recycling. Compared with the prior art where the flash vapor condensate enters the oil-water separation tank, since there is no steam pipeline at the bottom of the flash tank in this process and the number of coagulation kettles is three, ensuring the subsequent solvent removal capacity, the flash vapor condensate in this process directly enters the solvent buffer tank, saving the energy consumption of the solvent transfer pump and reducing the generation of sewage. In addition, the non-condensable gas in the oil cooler is incorporated into the tail gas collection system and sent to the device RTO for treatment.

[0038] Recover the waste heat of the solvent vapor after flash evaporation. By integrating temperature, pressure, and flow sensors, collecting all the data and connecting it to an external large model, and performing deep learning through AI, the optimal operating point is provided to achieve dynamic energy saving. At the same time, feedforward-feedback control is introduced to respond to feed fluctuations in advance and reduce solvent losses and increased energy consumption caused by pressure fluctuations. Therefore, the preparation process of the present invention is more refined and has a higher degree of intelligence.

[0039] The glue liquid at the bottom of the pre-flash tank is sent to the static mixer by the glue liquid feed pump at the bottom of the tank, and after being fully mixed with the dispersant, it enters the subsequent first coagulation kettle, and the residual solvent is further removed by steam stripping. To avoid problems such as excessive viscosity of the glue liquid causing pipeline blockage and uneven mixing of the dispersant, the flash evaporation amount of the glue liquid solvent at the bottom of the pre-flash tank is controlled at 65%-80%. This can not only ensure the solvent removal efficiency, reduce the subsequent steam stripping steam consumption, but also ensure that the glue liquid does not have too high viscosity and cannot be transported. Preferably, an anti-scaling agent can be regularly injected into the pre-flash tank to avoid coking caused by rubber particle residues.

[0040] In some embodiments of the present application, in S20, the gaseous solvent at the top of the pre-flash tank is sucked out by a vacuum pump, so that the pressure inside the pre-flash tank is maintained at a slightly negative pressure; wherein, the pressure range of the slightly negative pressure is from -0.08 MPa to 0.01 MPa.

[0041] By sucking out the gaseous solvent at the top of the pre-flash tank through a vacuum pump, the pressure inside the tank can be effectively reduced, the flash evaporation efficiency can be effectively improved, and the solvent in the glue liquid can be promoted to volatilize or separate. The control of the slightly negative pressure is crucial for the processing of the glue liquid, which can avoid excessive evaporation or unnecessary material loss caused by too low pressure, and at the same time ensure that the glue liquid can maintain its stability under mild conditions. The slightly negative pressure range of -0.08 MPa to 0.01 MPa provides an environment for precise control, which can effectively promote the volatilization of the glue liquid without causing excessive damage to its components.

[0042] In some embodiments of the present application, in S20, the glue liquid at the bottom of the pre-flash tank is sent to a static mixer through a glue liquid feed pump, mixed with a dispersant, and then sent to a coagulation kettle; wherein, the dispersant includes sodium polycarboxylate, sodium oleate or sodium stearate.

[0043] The present invention further optimizes the mixing step of the glue liquid and the dispersant in the process of glue liquid treatment. Specifically, in step S20, the glue liquid at the bottom of the pre-flash tank is sent to a static mixer through a glue liquid feed pump, mixed with the dispersant in the mixer, and then the mixed glue liquid is sent to a coagulation kettle for subsequent treatment. Sodium polycarboxylate can provide good dispersion effect and reduce the non-uniformity in the glue liquid; fatty acid salt dispersants such as sodium oleate and sodium stearate can also effectively prevent particle aggregation in the glue liquid, which helps to improve the fluidity and stability of the glue liquid.

[0044] Furthermore, the use of the static mixer in combination with the dispersant can not only improve the dispersion efficiency but also reduce the energy consumption. Compared with the traditional mechanical mixing method, the static mixer is easy to operate and has low energy consumption, with higher economy and environmental protection.

[0045] In some embodiments of the present application, after the gaseous solvent undergoes secondary heat exchange through an oil cooler, the condensed liquid solvent flows into a solvent buffer tank, and the non-condensable gas in the oil cooler is introduced into a tail gas collection system.

[0046] The present invention relates to the recovery and condensation process of the gaseous solvent. Among them, the gaseous solvent undergoes a secondary heat exchange process when passing through the oil cooler, and the temperature of the gaseous solvent is reduced through the heat exchange between the oil and the gas. In this process, the oil passing through the oil cooler absorbs the heat of the gaseous solvent during the heat exchange process, thereby cooling the gaseous solvent and promoting its condensation into a liquid solvent. Further, the liquid solvent is effectively collected and flows into the solvent buffer tank for storage.

[0047] In the oil cooler, some gases may not be completely condensed, i.e., non-condensable gases, which are introduced into the tail gas collection system for further treatment. The tail gas collection system is equipped with a purification device that can treat and discharge these gases to ensure compliance with environmental protection requirements. The flash vapor condensate of this process directly enters the solvent buffer tank, saving the energy consumption of the solvent transfer pump and reducing the generation of sewage.

[0048] In some embodiments of the present application, the flash evaporation amount of the glue liquid at the bottom of the pre-flash evaporation tank is controlled at 65% - 80%.

[0049] The pre-flash evaporation tank is used for the pretreatment process of the glue liquid, in which the glue liquid undergoes flash evaporation under certain pressure and temperature, that is, through the change of temperature or pressure, a part of the volatile components in the glue liquid are vaporized into the gas phase. This process can remove unnecessary components or impurities in the glue liquid, and at the same time improve the quality and performance of the glue liquid. To avoid the problem of excessive viscosity of the glue liquid causing pipeline blockage and uneven mixing of the dispersant, the flash evaporation amount of the glue liquid solvent at the bottom of the pre-flash evaporation tank is controlled at 65% - 80%. In this way, it can not only ensure the removal efficiency of the solvent and reduce the subsequent stripping steam consumption, but also ensure that the glue liquid does not have the problem of excessive viscosity and cannot be transported.

[0050] In some embodiments of the present application, the set temperature for preheating the glue liquid in the glue liquid preheater is 80°C - 100°C.

[0051] By heating the glue liquid to the set temperature, the fluidity of the glue liquid can be improved and the viscosity can be reduced, ensuring that the glue liquid is more stable and efficient in the subsequent processing and reaction processes. After the glue liquid is preheated, its viscosity can be reduced, making the subsequent processing technology smoother. In addition, preheating can also ensure that the components in the glue liquid are evenly distributed at the required temperature, avoiding uneven or unstable treatment effects caused by temperature differences.

[0052] In some embodiments of the present application, the residence time of the glue liquid in the pre-flash evaporation tank ≥ 120 seconds.

[0053] By setting the residence time of the glue liquid in the pre-flash evaporation tank, the glue liquid has enough time for sufficient flash evaporation reaction. At this time, the components in the glue liquid can be fully separated and volatilized during this process, thereby improving the effect of the flash evaporation process. Compared with atmospheric flash evaporation, the flash evaporation efficiency of the vacuum flash evaporation process of the present invention is higher. Therefore, the residence time of the glue liquid in the pre-flash evaporation tank is short and the separation efficiency is high. This can also avoid the problems of rubber coking and sticking to the kettle wall caused by long-term residence.

[0054] In some embodiments of the present application, the condensation system is provided with a temperature-pressure cascade control system, which is used to synchronously adjust the outlet temperature of the glue liquid preheater when adjusting the pressure of the preflash tank; wherein, the temperature-pressure cascade control system includes a main loop and a secondary loop, the main loop is used to control the pressure of the preflash tank, and the secondary loop is used to control the outlet temperature of the glue liquid preheater.

[0055] In the temperature-pressure cascade control system, the main loop controls the pressure of the preflash tank, and the secondary loop is mainly responsible for controlling the outlet temperature of the glue liquid preheater. Through the synergistic effect between the main loop and the secondary loop, when the main loop adjusts the pressure of the preflash tank, the secondary loop synchronously adjusts the temperature of the preheater to ensure the coordination relationship between temperature and pressure during the glue liquid preheating process, thereby avoiding the problem of inability to transport due to too high rubber concentration.

[0056] In some embodiments of the present application, the preheater includes a first temperature transmitter and a gas-phase solvent outlet regulating valve; the preflash tank includes a pressure transmitter, a pressure regulating valve, a flowmeter, a feed regulating valve, and a level gauge; the oil cooler includes a second temperature transmitter and a return water flow regulating valve.

[0057] The first temperature transmitter is used to monitor the temperature in the preheater and transmit the temperature data in real time to adjust the temperature control of the glue liquid and ensure that the glue liquid reaches the required temperature during the preheating process. The gas-phase solvent outlet regulating valve is used to control the flow rate of the gas-phase solvent, adjust its outflow rate, thereby controlling the mixing ratio and treatment effect of the gas-phase solvent and the glue liquid, and optimizing the preheating process of the glue liquid.

[0058] The pressure transmitter can monitor the pressure change in the preflash tank and feedback the data to the control system in real time to ensure that the pressure in the flash tank is stable within the required range. The pressure regulating valve automatically adjusts the pressure of the preflash tank according to the data of the pressure transmitter to ensure that it operates at the optimal working pressure. The flowmeter is used to measure the flow rate of the glue liquid entering the preflash tank to help the control system monitor and adjust the flow rate. The feed regulating valve is used to adjust the inlet amount of the glue liquid according to the data of the flowmeter to ensure that the glue liquid enters the preflash tank at an appropriate flow rate and avoid the influence of too much or too little input on the treatment effect. The level gauge is used to monitor the liquid level in the preflash tank to ensure that the liquid level is within a reasonable range and prevent system imbalance caused by too high or too low liquid level.

[0059] The second temperature transmitter is used to measure the temperature in the oil cooler and transmit the data in real time to control and adjust the cooling effect of the oil cooler. The return water flow regulating valve adjusts the return water flow according to the data of the temperature sensor to ensure that the cooling effect of the oil cooler reaches the best state, thereby preventing the system from reducing efficiency or being damaged due to overheating.

[0060] In some embodiments of the present application, a logic interlock control is formed between the first temperature transmitter and the gas-phase solvent outlet regulating valve; a logic interlock control is formed between the pressure transmitter, the pressure regulating valve, and the vacuum pump; a logic interlock control is formed between the flowmeter, the feed regulating valve, and the vacuum pump; a logic interlock control is formed between the level gauge and the glue liquid feed pump; a logic interlock control is formed between the second temperature transmitter and the return water flow regulating valve.

[0061] The present invention further optimizes the automatic control and collaborative work in the glue liquid treatment process by establishing a logic interlock control between various key components. Specifically, multiple sensors in the system coordinate with devices such as regulating valves and pumps through a logic interlock mechanism to ensure that each link can make synchronous adjustments based on real-time data.

[0062] Figure 1 It is a process flow diagram of the pre-flash evaporation energy-saving method for the coagulation system of the SSBR production device provided by the embodiment of the present invention.

[0063] The coagulation system includes a pre-flash evaporation tank 5, a glue liquid preheater 1, an oil cooler 2, a vacuum pump 11, a glue liquid feed pump 12, and a coagulation kettle; the pre-flash evaporation energy-saving method includes the following steps: S10, preheating the glue liquid from the polymerization system to a set temperature through the glue liquid preheater 1; S20, feeding the preheated glue liquid into the pre-flash evaporation tank 5, sucking out the gas-phase solvent at the top of the pre-flash evaporation tank 5 through the vacuum pump 11 to maintain a slightly negative pressure in the pre-flash evaporation tank 5; the glue liquid at the bottom of the pre-flash evaporation tank 5 is sent to the static mixer 4 through the glue liquid feed pump 12, mixed with the dispersant, and then sent to the coagulation kettle.

[0064] Among them, the gas-phase solvent sucked out through the vacuum pump 11 enters the glue liquid preheater 1 for primary heat exchange, and then enters the oil cooler 2 for secondary heat exchange to recover the steam waste heat of the gas-phase solvent. After the gas-phase solvent undergoes secondary heat exchange in the oil cooler 2, the condensed liquid-phase solvent flows into the solvent buffer tank 10, and the non-condensable gas in the oil cooler 2 is introduced into the tail gas collection system.

[0065] The condensation kettle includes a first kettle 6, a middle kettle 7, and a last kettle 8. The heavy component A is drawn out from the bottom of the first kettle 6 via the first kettle colloid water pump 13 and sent to the middle kettle 7. The heavy component B is drawn out from the bottom of the middle kettle 7 via the middle kettle colloid water pump 14 and sent to the last kettle 8. The glue solution is drawn out from the bottom of the last kettle 8 via the last kettle colloid water pump 15 and sent to the glue solution discharge port 22. The light component A is drawn out from the top of the first kettle 6, heat-exchanged through the oil-gas condenser 3, and then sent to the oil-water separation tank 9. The water separated in the oil-water separation tank 9 is sent to the hot water feed port 20 via the separation water pump 16, and the separated oil is sent to the solvent buffer tank 10 to obtain wet solvent, which is then sent to the wet solvent discharge port 23 via the solvent external delivery pump 17. The light component B is drawn out from the top of the middle kettle 7 and sent to the first kettle 6. The light component C is drawn out from the top of the last kettle 8, sucked by the steam ejector pump 18, and then sent to the first kettle 6. The reactant feed port 19 is connected to the glue solution preheater 1, the hot water feed port 20 is connected to the first kettle 6, and the dispersant feed port 21 is connected to the static mixer 4.

[0066] The process parameters of the pre-flash evaporation energy-saving method are as follows: (1) Temperature control: It is necessary to control the temperature of the glue solution to avoid rubber thermal degradation caused by too high temperature; control range: 80°C - 100°C; control method: By integrating temperature, pressure, and flow sensors, after collecting all data and accessing an external large model, the external large model will provide the best operating point after deep learning on the data set.

[0067] (2) Pressure control: The lower the pressure in the pre-flash evaporation tank, the higher the solvent vaporization rate. It is necessary to avoid excessive decompression resulting in glue solution foaming or entraining rubber particles; control range: -0.08 MPa to 0.01 MPa; control method: By connecting to a vacuum pump to control the pressure in the tank to maintain a slight negative pressure. At the same time, through the pressure transmitter and pressure regulating valve of the pre-flash evaporation tank, the vacuum degree in the tank can be adjusted in real time.

[0068] (3) Feed flow rate and residence time: Too low flow rate affects production capacity, and too high flow rate affects separation effect; control method: Establish a control loop through the mass flow rate of the feed line and the feed regulating valve to stabilize the feed flow rate. Residence time: Ensure that the residence time of the glue solution in the pre-flash evaporation tank ≥ 120 seconds.

[0069] (4) Liquid level control: Too high liquid level leads to insufficient gas phase space and affects the flash evaporation effect, and too low liquid level will cause the pump to run dry; control range: 40 ± 5%; control method: Interlock the glue solution feed pump at the bottom of the tank through a radar level gauge to control the liquid level.

[0070] (5) Glue solution characteristics: When the solvent content in the feed glue solution fluctuates, it is necessary to synchronously adjust the pressure and temperature; avoid too high rubber viscosity affecting the glue solution transportation.

[0071] The process instrument control scheme of the pre-flash evaporation energy-saving method is as follows: 1. Main Instrument Selection (1)Feed temperature: Integrated temperature transmitter; Actuator: Gas-phase solvent outlet regulating valve of preheater; Interlock logic: When the feed temperature exceeds the limit (≥120°C), close the glue feed regulating valve and open the gas-phase solvent outlet regulating valve of the preheater.

[0072] (2)Pre-flash tank pressure: Pressure transmitter; Actuators: Pressure regulating valve, vacuum pump; Interlock logic: When the pressure rises, increase the power of the vacuum pump. When the pressure ≥ 0.02 MPa, trigger the vent interlock and start the safety valve.

[0073] (3)Feed flow: Coriolis mass flowmeter; Actuators: Glue feed regulating valve, vacuum pump; Interlock logic: When the flow is abnormal (±10%), trigger a process alarm and synchronously adjust the frequency of the vacuum pump.

[0074] (4)Pre-flash tank liquid level: Radar level gauge; Actuator: Inverter of glue feed pump; Interlock logic: When the liquid level ≤ 20%, stop the pump. When the liquid level ≥ 70%, close the glue feed regulating valve slightly and increase the variable frequency power of the glue feed pump.

[0075] (5)Oil cooler condensate temperature: Integrated temperature transmitter; Actuator: Circulating water return flow regulating valve; Interlock logic: When the condensate temperature is too high, open the circulating water return flow regulating valve.

[0076] 2. Control Loop Design (1)Temperature-pressure cascade control: Main loop: Pre-flash tank pressure control (set value is determined according to the solvent boiling point); Sub-loop: Preheater outlet temperature control to ensure synchronous temperature adjustment during pressure regulation.

[0077] (2)Liquid level-flow feedforward control: Predict the feed demand according to the liquid level change, and adjust the opening of the glue feed valve in advance to reduce the liquid level fluctuation.

[0078] (3)Safety interlock system: When the pressure > 0.02 MPa, interlock to close the glue feed regulating valve and start emergency pressure relief; When the liquid level > 80%, interlock to stop the pump and alarm.

[0079] 3. Process Parameters (1)Feed temperature: Set value: 85°C; Fluctuation range: ±2°C.

[0080] (2)Pre-flash tank pressure: Set value: -0.07 MPa; Fluctuation range: ±5 kPa.

[0081] (3)Feed flow: Set according to the device load.

[0082] (4)Pre-flash tank liquid level: Set value: 40%; Fluctuation range: ±5%.

[0083] An embodiment of the present invention provides an energy-saving method for pre-flash evaporation of a coagulation system in an SSBR production device. Taking lithium-based anionic polymer SSBR as an example, the solvent is prepared by mixing cyclohexane and n-hexane in a mass ratio of 9:1. The boiling point of cyclohexane is 80.7 °C, and the boiling point of n-hexane is 69 °C.

[0084] Example 1: The temperature of the rubber solution after polymerization is 70 °C - 80 °C. After recovering the waste heat (80 °C - 120 °C) of the solvent flash vapor through a rubber solution preheater, the temperature of the rubber solution rises to 85 °C. The flash evaporation amount of the solvent is 65 wt%, the feed flow rate is 40 m³ / h. After the flash-evaporated rubber solution is mixed with the dispersant sodium stearate, it enters the coagulation kettle and steam stripping is carried out to further recover the solvent in the rubber solution, and then it is sent to the post-treatment unit for drying treatment. Among them, the pressure of the coagulation kettle is 10 kPa - 15 kPa, and the temperature is 100 °C - 120 °C.

[0085] The result is: the solvent oil consumption is 13.7 kg / ton of rubber, and the steam consumption is 2.08 tons / ton of rubber.

[0086] Comparative Example 1: The temperature of the rubber solution after polymerization is 70 °C - 80 °C. Through a heat exchanger (external heat source), the temperature of the rubber solution is raised to 120 °C. The flash evaporation amount of the solvent is 40 wt%. It is pumped into Coagulation Kettle I at a flow rate of 35 m 3 / h. The kettle is filled with about 0.4% of dry rubber mass of polycarboxylate sodium, sodium oleate or sodium stearate as the dispersant, stays in Coagulation Kettle I for 20 min, and then is pumped into Coagulation Kettle II by a particle pump and stays in Coagulation Kettle II for 20 min. The rubber particles are sent to the post-treatment unit for drying treatment. Among them, the temperature of Coagulation Kettle I is controlled at 98 °C, the pressure is -0.05 MPa to 0.09 MPa, the temperature of Coagulation Kettle II is controlled at 101 °C, and the pressure is 0 MPa to 0.09 MPa.

[0087] The result is: the solvent oil consumption is 15 kg / ton of rubber, and the steam consumption is 2.8 tons / ton of rubber.

[0088] Comparative Example 2: The temperature of the rubber solution after polymerization is about 70 °C - 80 °C, the feed flow rate is 40 m³ / h, it is directly pumped into the coagulation kettle, and steam stripping is carried out. The pressure of the coagulation kettle is 10 kPa - 15 kPa, the temperature is 100 °C - 120 °C. After removing the solvent, it is sent to the post-treatment unit for dehydration and drying treatment.

[0089] The result is: the solvent oil consumption is 96 kg / ton of rubber, and the steam consumption is 5.6 tons / ton of rubber.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A pre-flash evaporation energy-saving method for the coagulation system of an SSBR production device, characterized in that, The condensation system includes a pre-flash tank, a rubber solution preheater, an oil cooler, a vacuum pump, a rubber solution feed pump, and a coagulation kettle; the pre-flash energy-saving method includes the following steps: S10. Preheat the rubber solution from the polymerization system to a set temperature through the rubber solution preheater; S20. Feed the preheated rubber solution into the pre-flash tank. The gas-phase solvent at the top of the pre-flash tank is sucked out through the vacuum pump, and the rubber solution at the bottom of the pre-flash tank is sent to the coagulation kettle through the rubber solution feed pump; Among them, the gas-phase solvent sucked out through the vacuum pump enters the rubber solution preheater for primary heat exchange, and then enters the oil cooler for secondary heat exchange to recover the steam waste heat of the gas-phase solvent.

2. The pre-flash evaporation energy-saving method according to claim 1, characterized in that In S20, the gas-phase solvent at the top of the pre-flash tank is sucked out through the vacuum pump, so that the pressure in the pre-flash tank is maintained at a slightly negative pressure; Among them, the pressure range of the slightly negative pressure is -0.08 MPa to 0.01 MPa.

3. The pre-flash evaporation energy-saving method according to claim 1, wherein In S20, the rubber solution at the bottom of the pre-flash tank is sent to a static mixer through the rubber solution feed pump, mixed with a dispersant, and then sent to the coagulation kettle; Among them, the dispersant includes sodium polycarboxylate, sodium oleate or sodium stearate.

4. The pre-flash evaporation energy-saving method according to claim 1, characterized in that After the gas-phase solvent undergoes secondary heat exchange in the oil cooler, the condensed liquid-phase solvent flows into the solvent buffer tank, and the non-condensable gas in the oil cooler is introduced into the tail gas collection system.

5. The pre-flash evaporation energy-saving method according to claim 1, wherein The flashing amount of the rubber solution at the bottom of the pre-flash tank is controlled at 65% - 80%.

6. The pre-flash evaporation energy-saving method according to claim 1, characterized in that, The set temperature for the rubber solution to be preheated in the rubber solution preheater is 80°C - 100°C.

7. The pre-flash evaporation energy-saving method according to claim 1, characterized in that The residence time of the rubber solution in the pre-flash tank is ≥120 seconds.

8. The pre-flash evaporation energy-saving method according to claim 1, characterized in that The condensation system is equipped with a temperature-pressure cascade control system, which is used to synchronously adjust the outlet temperature of the rubber solution preheater when adjusting the pressure of the pre-flash tank; Among them, the temperature-pressure cascade control system includes a main loop and a secondary loop. The main loop is used to control the pressure of the pre-flash tank, and the secondary loop is used to control the outlet temperature of the rubber solution preheater.

9. The pre-flash energy-saving method according to claim 1, wherein The preheater includes a first temperature transmitter and a gas-phase solvent outlet regulating valve; The pre-flash tank includes a pressure transmitter, a pressure regulating valve, a flowmeter, a feed regulating valve, and a level gauge; The oil cooler includes a second temperature transmitter and a return water flow regulating valve.

10. The pre-flash energy-saving method according to claim 9, wherein A logic interlock control is formed between the first temperature transmitter and the gas-phase solvent outlet regulating valve; A logic interlock control is formed between the pressure transmitter, the pressure regulating valve, and the vacuum pump; A logic interlock control is formed between the flowmeter, the feed regulating valve, and the vacuum pump; A logic interlock control is formed between the level gauge and the rubber solution feed pump; A logic interlock control is formed between the second temperature transmitter and the return water flow regulating valve.

Images