Device and method for fluid devolatilization

Abstract

The present invention discloses a device and method for fluid devolatilization. The device includes a scraper film evaporator, a heating liner, a nozzle and a booster pump. By coupling the static devolatilization function with the dynamic devolatilization function, the heating liner for static devolatilization and the matching nozzle are arranged in the device for dynamic devolatilization, which not only simplifies the structure but also reduces energy consumption. On the one hand, the volatiles removed by the static devolatilization and the dynamic devolatilization can be processed and discharged together. On the other hand, the pressurized heating liner is used in combination with the nozzle for processing, so that the fluid after injection can not only be flash-evaporated under reduced pressure, but also is conducive to the uniform distribution of the remaining fluid on the inner wall of the first cylinder. The structure is simple and the efficiency is high, and energy saving and consumption reduction are reduced. Through this ingenious combination, multiple goals are achieved at one stroke.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, in particular to a device for devolatilizing fluids, especially polymer fluids, and a method for performing primary devolatilization and deep devolatilization using the device to obtain a low-VOC polymer product. Background Art

[0002] Fluid devolatilization technology is very common in the chemical industry and is widely used. Especially at a time when environmental protection is becoming increasingly important, green and environmentally friendly materials require very delicate handling of volatiles in the front-end process. Fluid devolatilization equipment is divided into static devolatilization and dynamic devolatilization. Static devolatilization, such as flash devolatilization, falling film devolatilization, and falling strip devolatilization, can generally achieve the removal of a large amount of volatiles; dynamic devolatilization, such as scraper devolatilization, screw devolatilization, and fluidized bed devolatilization, can generally achieve deep removal of a small amount of volatiles. However, whether it is static devolatilization or dynamic devolatilization, it is generally used alone or in combination, which will make the system more complicated. The additional transportation, heating, and control systems not only increase investment, but also bring risks such as system blockage, low mass transfer and separation efficiency of volatiles such as monomers and solvents.

[0003] At the same time, for some polymers in the material system that are heat-sensitive or heat-instable, have low degradation temperatures or high glass transition temperatures, and the heavy components in the volatile matter have high boiling points, complex devolatilization systems or combinations will cause the material to stay for too long, leading to product deterioration.

[0004] At present, domestic and foreign enterprises and institutions have carried out a lot of research work on the research of polymer devolatilization equipment. For different systems, domestic and foreign companies have announced various devolatilization equipment. CN102858415A describes an apparatus and method for devolatilizing a flowable material using a plate heater with a heating channel. The design or operation of the heating channel ensures that the flowable material remains above its bubble point pressure during the process of passing through a larger first area and inducing flash evaporation in a smaller second area of ​​the heating channel or downstream. The important innovation of this invention is that the plate heating has high efficiency and can improve the devolatilization processing capacity. CN1986619A describes a static devolatilization device for treating polymers containing liquids. A preheater placed in a container heats the material, and then it enters a phase separation chamber. The gas phase enters the container from the upper opening of the phase separation chamber, and the liquid phase enters the container from the lower opening of the phase separation chamber. After concentration, it is discharged from the bottom. CN105008011A discloses a static devolatilization device suitable for devolatilizing viscous liquids containing volatile components. The device includes a phase separation chamber at the material inlet for processing the viscous liquid in the first devolatilization step, and a multi-stage sieve plate devolatilization device is provided below the phase separation chamber and above the lower storage tank area to increase the residence time of the polymer system and achieve a better devolatilization effect. CN112933665A describes a devolatilization system for high-viscosity fluids, and the invention provides a devolatilization system for high-viscosity fluids. The atomizing separator has a vertical tank body, and a two-phase flow atomizing nozzle is provided in the tank body chamber. The high-viscosity fluid to be devolatilized is formed into atomized droplets and volatile components through the atomizing nozzle. The atomized droplets are separated from the polymer and volatile components under the action of the drag force of the conveying gas.

[0005] In summary, the traditional strip devolatilization equipment and static devolatilization equipment can achieve the removal of a large amount of volatiles. However, for some systems that require deep or extreme devolatilization, such as polymer systems with high viscosity, it is difficult to obtain satisfactory results by enhancing heat transfer or increasing residence time. It is necessary to combine dynamic devolatilization equipment such as screws to enhance mass transfer and heat transfer to achieve deep removal of volatiles. The system is very complex. Summary of the Invention

[0006] The object of the present invention is to provide an apparatus and method for fluid devolatilization, which achieves excellent devolatilization effect by cleverly combining static devolatilization with dynamic devolatilization, especially for polymer systems with high viscosity.

[0007] To achieve one aspect of the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0008] A fluid devolatilization apparatus, comprising:

[0009] A scraped film evaporator comprises a first cylinder and a scraper disposed within the first cylinder, the scraper being driven by a motor to rotate along the inner wall of the first cylinder to form a fluid film on the inner wall of the first cylinder; a first heating element is disposed on the outer wall of the first cylinder to provide heat required for evaporation of the fluid film;

[0010] The heating liner comprises a second cylinder arranged in the first cylinder and a second heating element arranged in the second cylinder;

[0011] Nozzles are evenly distributed on the surface of the second cylinder, and are used to spray the heated liquid fluid in the second cylinder to the inner wall area of ​​the first cylinder covered by the scraper when it rotates; and

[0012] The booster pump is used to pump the fluid to be devolatilized into the second cylinder for heating and provide the necessary pressure head for the fluid so that the fluid is in a superheated single liquid phase or liquid / liquid phase state after being heated by the heating element.

[0013] In the present invention, the booster pump provides the necessary pressure boost for the fluid to be devolatilized, and its type is preferably a positive displacement pump, more preferably a rotor pump, a gear pump and a screw pump, all of which are known in the art and will not be described in detail here.

[0014] In the present invention, the second barrel of the heating liner is connected to a booster pump via a pipe to receive fluid. A second heating element is provided within the heating liner to continuously heat the input fluid. The second heating element can be an electric heating element, a thermal fluid heating element, or a combination of the two, preferably a thermal fluid heating element, such as a thermal oil heating assembly. To enhance the heating effect, the second heating element can be a high-efficiency heat exchange tube, such as one with a large specific surface area and a heat exchange structure that enhances heat transfer.

[0015] In the present invention, the fluid is heated to superheat in the second cylinder by the built-in second heating element, the fluid temperature is higher than its bubble point, and the fluid is in a molten state, a liquid state, or a liquid / liquid state; the fluid in the second cylinder is usually full, and the booster pump continuously replenishes the fluid while the fluid is ejected.

[0016] In a preferred embodiment, the wall of the second cylinder is a sandwich structure to form a sandwich chamber in the sandwich, thereby facilitating heat preservation for efficient flash evaporation. Further preferably, the device also includes an air inlet pipe connected to the sandwich chamber and inputting gas into the sandwich chamber; the nozzle is an atomizing nozzle, including a liquid inlet and a gas inlet, the gas inlet being connected to the sandwich chamber, and the liquid inlet being connected to the interior of the first cylinder, such as a Venturi structure nozzle, so that the gas in the sandwich chamber (hereinafter referred to as the sandwich gas) can be used to assist the fluid in forming droplets or liquid sheets in the atomizing nozzle, thereby increasing the mass transfer area and further improving the flash evaporation effect; in addition, the gas in the sandwich chamber can also effectively reduce the partial pressure of volatiles, playing the role of stripping volatiles; in addition, for fluids with high viscosity such as polymers, the gas in the sandwich chamber can also increase foaming in the fluid, such as in the polymer, to enhance mass transfer, which is also beneficial to subsequent concentration.

[0017] In a preferred embodiment, the Henry coefficient of the interlayer gas in the volatile matter is not less than 40 MPa (A), preferably the Henry coefficient is not less than 80 MPa (A), so as to better promote the separation of volatile matter; the interlayer gas can be one or more of water vapor, air, nitrogen, argon, ethylene, propylene, methane, ethane, propane, hydrogen and carbon dioxide, preferably nitrogen. It can be understood in the art that in order to better reduce heat dissipation, the interlayer chamber can be selected to have a smaller thermal conductivity, such as a thermal conductivity not exceeding 0.1 W / (m.℃), preferably a thermal conductivity not exceeding 0.05 W / (m.℃), such as 0.02, 0.04 or 0.08 W / (m.℃). In some embodiments, the interlayer gas is heated by an external heater or directly heated by the high-temperature fluid in the heating liner through the partition wall to a temperature range of ±50℃ of the fluid temperature, preferably a temperature range of ±20℃, such as a temperature range of ±10℃, to reduce adverse effects during atomization.

[0018] In the present invention, the atomizing nozzle ejects the fluid from the heating inner container, and the liquid ejection velocity is preferably 0.1 to 5 m / s, more preferably 0.3 to 3 m / s, such as 0.5, 1, or 2 m / s. Through the suction effect of the fluid in the atomizing nozzle, the interlayer gas is sucked into the negative pressure area of ​​the nozzle and further mixed with the fluid in the nozzle to form a foaming system. Preferably, the mass ratio of the interlayer gas to the fluid sucked into the atomizing nozzle is 1:100 to 1:50, such as 1:60 or 1:80. The fluid forms droplets or liquid sheets in the evaporation chamber through the atomizing nozzle. Preferably, the hydraulic diameter of the droplets or liquid sheets formed is 0.01 to 10 mm, such as 0.1, 0.5, 2, or 5 mm.

[0019] In some embodiments, the pressure of the interlayer gas can be increased. By pressurizing the interlayer gas, it enters the atomizing nozzle through a pressure differential and is dispersed in the fluid, forming droplets and / or liquid sheets containing bubbles. This is generally more suitable for fluids with higher viscosities, such as fluids with viscosities of 500 cp or higher, such as 800 or 1000 cp. In other embodiments, only a single-phase fluid enters the nozzle without the introduction of interlayer gas, and the interlayer chamber serves only as a thermal insulation layer, which can also achieve good flash evaporation effects.

[0020] In the present invention, the fluid droplets or liquid sheets ejected through the nozzle are flash evaporated under reduced pressure in the first cylinder to obtain a once concentrated fluid. The pressure in the first cylinder can be provided by a negative pressure generating device connected to the volatile outlet. Preferably, the pressure in the first cylinder does not exceed 1.5 MPa(A), preferably does not exceed 0.4 MPa(A), and more preferably is 0.1-50 KPa(A), such as 0.1 KPa(A), 0.5 KPa(A), 1 KPa(A), 5 KPa(A), 10 KPa(A), 30 KPa(A), 40 KPa(A), 60 KPa(A), 100 KPa(A) or 1 MPa(A); the once flash evaporation concentration in the first cylinder can be an adiabatic process, and the weight of the volatile matter removed from the fluid can account for about 50% to 95% of the total volatile matter, such as 60%, 80% or 90%.

[0021] In the present invention, the fluid after one concentration, for example, its heavy component content can reach more than 60%, such as 60%-90%, is further sprayed onto the inner surface of the scraped film evaporator under the inertia of the nozzle spray for deep concentration; after deep evaporation and concentration, the heavy component content in the fluid can reach more than 95%, such as 95% to 99.99%, preferably 98% to 99.99%. Scraped film evaporators are commonly used in this field, wherein the first cylinder can adopt a more conventional layout, for example, a volatile component outlet is provided at the top of the first cylinder and a concentrated liquid outlet is provided at the bottom. In some embodiments, the lower part of the first cylinder can be connected to a conical, circular or elliptical lower head, preferably a conical lower head. The contact surface of the first cylinder with the fluid is preferably made of metal, and the surface is polished, preferably with a polishing requirement of Ra≤0.8μm to reduce resistance.

[0022] In the present invention, a first heating element is provided on the outside of the first cylinder. The first heating element can be electric heating or hot fluid outer jacket heating, such as an outer coil or buckle tube, or some combination thereof, preferably hot fluid outer jacket heating; the heating medium in the jacket is a high-temperature medium, such as steam, molten salt, thermal oil or hot water. In some embodiments, in order to ensure the effective evaporation and concentration of the fluid film on the inner wall of the first cylinder, the temperature of the heat medium in the heating jacket can be 5 to 50°C higher than the temperature of the fluid body, preferably 10-30°C, more preferably 15 to 20°C, such as 10, 20 or 40°C; in some embodiments, the heat transfer coefficient of the first cylinder is 50 to 800W / (m 2 .℃), preferably 100~500W / (m 2 .℃), such as 200, 300, 400 or 600W / (m 2 .℃).

[0023] In the present invention, the scraper used for film application is driven by a motor. The scraper rotates in close proximity to the inner wall of the first cylinder to scrape the film, thereby forcing the fluid to form a film and renewing the surface. In some embodiments, the scraper's rotation speed can be 10 to 500 RPM, preferably 50 to 300 RPM, such as 100 or 200 RPM. To accommodate the heated inner container, the length of the central shaft driven by the motor can be shortened, and the upper portion of the scraper can be fixed to the lower portion of the central shaft via a fixing member. This allows the heated inner container to be arranged in an area below the central shaft, surrounded by multiple (e.g., three or four) scrapers.

[0024] The scraper forces the fluid ejected from the nozzle and concentrated once to form a film on the inner surface of the first cylinder, so that the volatile matter is fully exposed to the evaporation surface. At the same time, the uniform film formation on the inner surface of the first cylinder increases the mass transfer and heat transfer area and reduces the mass transfer and heat transfer resistance. In some embodiments, the film thickness is about 0.1 mm to 10 mm, and preferably the film thickness is 0.1 mm to 2 mm, such as 0.2, 0.5, 1, 4, 6 or 8 mm.

[0025] In a preferred embodiment, the scraper is partially or completely provided with comb-shaped teeth on one side close to the inner wall of the first cylinder, and the angle α between the comb-shaped teeth and the central axis of the first cylinder is 30 to 75°, preferably 45 to 60°, which is conducive to transporting the deeply concentrated fluid downward to facilitate the concentration of fluid with higher viscosity.

[0026] In the present invention, the volatile matter concentrated once and the volatile matter evaporated by the thin film all leave the volatile matter outlet together, and the treatment is efficient. In some embodiments, in order to reduce the entrainment of fluid in the volatile matter, a static demister is also provided in the first cylinder, such as below the volatile matter outlet; or in other cases, in order to reduce entrainment, a dynamic demister is provided on the top of the rotor of the film-forming scraper, which can also achieve a better effect of preventing mist entrainment; in addition, preferably, in order to prevent mist entrainment, the rising gas velocity of the gas phase volatile matter in the first cylinder of the evaporator does not exceed 20m / s, more preferably does not exceed 10m / s, such as 5m / s.

[0027] In another aspect of achieving the above object, the present invention further provides a method for devolatilizing a fluid using the above apparatus, comprising:

[0028] (1) The superheated fluid in the second cylinder heated by the second heating element is ejected into the first cylinder through the nozzle under the action of the booster pump for flash evaporation to complete the primary concentration of the fluid;

[0029] (2) The rotation of the scraper forms a fluid film on the inner wall of the first cylinder after the first concentration is completed, and the residual volatile matter is further evaporated after being heated by the first heating element to obtain a deeply concentrated fluid.

[0030] In some embodiments, the fluid is a polymer melt or a polymer solution, and the volatile component is a solvent or a monomer; preferably, the fluid may include polyolefin elastomer (POE), acrylonitrile-butadiene-styrene copolymer (ABS), acrylate-styrene-acrylonitrile graft copolymer (ASA), polymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC), polyoxymethylene (POM), low-density polyethylene (LDPE), ethylene-propylene non-conjugated diene terpolymer (EPDM) and isocyanate adducts, such as TDI trimer, HDI trimer, HDI biuret, IPDI trimer, etc. One or more.

[0031] In the present invention, all percentages or percentage contents involved are by mass unless otherwise specified.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) The equipment of the present invention couples the static devolatilization function with the dynamic devolatilization function, and creatively arranges the heating liner for static devolatilization and the matching nozzle in the equipment for dynamic devolatilization, which not only simplifies the structure but also reduces energy consumption. On the one hand, the volatiles removed by static devolatilization and dynamic devolatilization can be processed and discharged together. On the other hand, the use of the pressurized heating liner in combination with the nozzle treatment can not only reduce the pressure and flash evaporate the fluid after injection, but also facilitate the uniform distribution of the remaining fluid on the inner wall of the first cylinder. The structure is simple and efficient, and energy saving and consumption reduction are achieved. Through this clever combination, multiple goals are achieved at one stroke.

[0034] (2) For some systems that require deep or extreme devolatilization, such as polymer systems with high viscosity, static devolatilization equipment and dynamic devolatilization equipment are generally conventionally combined. However, this combined system is very complex and requires the addition of additional delivery pumps, heat exchangers, pipelines, instruments and control units, etc., which requires a very large investment. Moreover, when the fluid is transported between different devices, on the one hand, due to the high viscosity, a high temperature must be maintained to maintain fluidity. On the other hand, maintaining a high temperature for a long time can easily lead to product decomposition, making it difficult to balance the two. The present invention achieves excellent devolatilization effect by innovatively coupling static and dynamic devolatilization processes and synergistically enhancing heat transfer, mass transfer and devolatilization kinetics.

[0035] (3) The heating element designed into the heating liner of the present invention facilitates heating the fluid in a short time, thereby controlling the fluid's thermal residence time to ensure that the material does not degrade or deteriorate. At the same time, the combination of the heating liner and the nozzle is more compact and has a greater processing capacity than traditional strip devolatilization.

[0036] (4) The wall of the second cylinder in the present invention can be set as a sandwich structure, which is conducive to efficient flash evaporation on the one hand. On the other hand, when the heated fluid is sprayed into the evaporation chamber through the atomizing nozzle, the interlayer gas stored in the interlayer is sucked out. The interlayer gas can promote the atomization and foaming of the fluid while reducing the partial pressure of the volatile matter, thereby greatly enhancing the mass transfer process. The devolatilization efficiency is increased by 20% to 30% compared with the traditional strip devolatilization, achieving multiple goals at one stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of an embodiment of a fluid devolatilization apparatus according to the present invention;

[0038] Figure 2 for Figure 1 Schematic diagram of the structure of the middle scraper;

[0039] Figure 3 The devolatilization system used in Comparative Example 1;

[0040] Figure 4 The devolatilization system used in Comparative Example 2;

[0041] Figure 1 and 2 The symbols in the figure are as follows: scraped film evaporator 101, volatile outlet 105, concentrate outlet 104, first cylinder 111, scraper 112, fixing part 113, central rotating shaft 114, first heating element 116, defoaming zone 201, devolatilization zone 202, concentrate zone 203, comb-shaped rack 212, heating liner 110, second cylinder 106, second heating element 107, interlayer chamber 109, nozzle 108, booster pump 102, fluid feed pipe 103. DETAILED DESCRIPTION

[0042] The present invention is further described below with reference to the embodiments and drawings. However, the present invention is not limited to the listed embodiments but also includes equivalent improvements and variations of the technical solutions defined in the claims attached to the present application.

[0043] The fluid devolatilization equipment and devolatilization method provided by the present invention are particularly suitable for mixed fluids containing high-boiling-point heavy components and volatile components, such as polymer solutions or melts. The high-boiling-point heavy components can be dimers, oligomers or polymers, and the volatile components can be solvents, additives or monomers.

[0044] like Figure 1 As shown, the device for fluid devolatilization of the present invention includes a scraper film evaporator 101, a heating liner 110, a nozzle 108 and a booster pump 102; the scraper film evaporator 101 includes a first cylinder 111 and a scraper 112 arranged in the first cylinder, the scraper 112 is connected to a central shaft 114 driven by a motor through a fixing member 113 so as to rotate along the inner wall of the first cylinder 111 to form a fluid film on the inner wall of the first cylinder; a first heating element 116 is provided on the outer wall of the first cylinder to provide the heat required for the evaporation of the fluid film; a volatile outlet 105 is provided at the top of the first cylinder and a concentrated liquid outlet 104 is provided at the bottom. Figure 2 As shown, the scraper 112 is partially or completely provided with comb-shaped teeth 212 on one side close to the inner wall of the first cylinder. The angle α between the comb-shaped teeth 212 and the central axis of the first cylinder is 30 to 75°, preferably 45 to 60°.

[0045] The heating liner 110 includes a second barrel 106 disposed within the first barrel and a second heating element 107 disposed within the second barrel. The second barrel has a sandwich structure with a wall forming a sandwich chamber 109 within the sandwich. The sandwich chamber 109 is also provided with an inlet pipe connected to the sandwich chamber 109 and configured to supply gas thereto. The booster pump 102 is disposed outside the first barrel and connected to the second barrel 106 via a pipe 103. It is used to pump the fluid to be devolatilized into the second barrel for heating by the second heating element 107, providing the necessary pressure head for the fluid, ensuring that the fluid is in a superheated single liquid phase or liquid / liquid phase state after being heated by the second heating element.

[0046] The nozzles 108 are evenly distributed on the surface of the second cylinder 106, and are used to spray the heated liquid fluid in the second cylinder to the inner wall area of ​​the first cylinder 111 covered by the scraper 112 when it rotates; the 108 is an atomizing nozzle, including a liquid inlet and a gas inlet, the gas inlet is connected to the interlayer chamber 109, and the liquid inlet is connected to the interior of the second cylinder 106.

[0047] During operation, the fluid to be devolatilized from upstream is pressurized by booster pump 102 and then enters second barrel 106 through feed pipe 103. The second heating element 107 provided therein can be a high-efficiency tubular heat exchanger. High-temperature thermal oil is passed through the heat exchange tubes to heat the material walls. The thermal oil circulates through the heat exchange tubes via an external device. The heated fluid is superheated, exceeding its bubble point. The pressure source provided by booster pump 102 maintains the fluid in a molten, liquid, or liquid-liquid state, filling second barrel 106. The fluid's residence time in second barrel 106 can vary from 5 to 60 minutes, depending primarily on the fluid's thermal stability and the target heating temperature. The wall of second barrel 106 is a sandwich structure, forming a sandwich chamber 109, which is connected to an external air inlet pipe, through which gas can be continuously replenished. The heated fluid in the second barrel 106 draws the gas stored in the interlayer chamber 109 through the atomizing nozzle 108, where it further mixes with the fluid in the nozzle to form a foaming system. After being ejected through the atomizing nozzle, the fluid forms droplets or liquid sheets in the devolatilization zone 202 within the first barrel 111, allowing the superheated fluid to undergo reduced-pressure flash evaporation in the devolatilization zone 202. The pressure in the first barrel 111 can be maintained by a pressure generating device (e.g., a vacuum pump) connected to the volatile outlet 105.

[0048] The fluid after a concentration, such as a polymer solution or a polymer melt, reaches the inner wall of the first cylinder 111 under the inertia of the jet. The fluid after a concentration is uniformly filmed under the rotating film scraping action of the film scraper 112, so that the volatile matter is fully exposed to the evaporation surface (the inner wall of the first cylinder). At the same time, the uniform film formation on the evaporation surface increases the mass transfer and heat transfer area and reduces the mass transfer and heat transfer resistance. The scraper 112 is driven by a motor.

[0049] The central rotating shaft 114 is driven and brought into close proximity with the evaporation surface, forcing the fluid to form a film and renew the surface. The comb-shaped racks 212 also facilitate downward fluid flow. The film-forming fluid undergoes secondary evaporation under the heating of the first heating element 116 (a thermal fluid outer jacket containing a high-temperature medium, preferably thermal oil). Together with the volatiles from the primary concentration, the fluid is defoamed in the defoaming zone 201 and then exits through the top volatile outlet 105. The deeply concentrated fluid from the secondary evaporation is then collected in the concentrated liquid zone 203 at the lower portion of the first cylinder before being discharged through the concentrated liquid outlet 104 at the bottom.

[0050] The present invention is further described below with reference to the examples.

[0051] Example 1

[0052] Use Figure 1 The equipment shown here removes volatiles from a polyolefin elastomer (POE) polymer solution. The monomers used are ethylene and octene, and the solvent is the isoparaffin Isopar E. The polymer solution, delivered from the reactor system at a flow rate of 30,000 kg / h and a temperature of 170°C, has a mass composition of approximately 17% POE, 77% solvent, 1% ethylene, and 5% octene. The polymer solution, acting as a fluid, is pressurized to 60-65 barG by booster pump 102 and then enters second barrel 106 for heating by second heating element 107. High-temperature thermal oil at 270-280°C is introduced into second heating element 107, heating the polymer solution from 170°C to 250-260°C. The fluid resides in the heating chamber for 6-8 minutes. The heated polymer solution is then drawn through atomizing nozzle 108 from nitrogen stored in interlayer chamber 109 to form a foaming system. The nitrogen temperature is approximately 220°C, and the mass ratio of the drawn interlayer gas to the fluid is approximately 1:95. The superheated fluid is then flashed under reduced pressure in first barrel 111, where the pressure is 30-40 kPa(A). Vacuum is provided by a vacuum pump connected to volatile outlet 105. To reduce mist entrainment, a defoaming device is provided in the first barrel. After one flash evaporation and concentration in the first cylinder, the mass content of polymer POE is 78-80%;

[0053] The polymer solution after the primary concentration reaches the inner wall of the first cylinder (111) under inertia. The primary concentrated fluid is uniformly formed into a film under the rotating film scraping action of the film scraper. The film thickness is about 1 to 2 mm. The first heating element 116 outside the first cylinder is a hot oil jacket. The hot oil temperature is 290°C (15 to 20°C higher than the fluid body). The film scraper is driven by a motor with a speed of 150RPM. Comb-shaped teeth are evenly arranged on the block film scraper. The angle α between the selected comb-shaped teeth and the central rotation axis (or the axial direction of the first cylinder) is 45° (such as Figure 2 ). Finally, after deep evaporation, the volatile matter (monomer and solvent) content of the polymer product in the fluid is reduced to 600-700 ppm, and the polymer has not been significantly degraded or decomposed.

[0054] Example 2

[0055] Use Figure 1 The equipment shown here removes volatiles from HDI (hexamethylene diisocyanate) trimer solutions. The volatiles are HDI, and the polycondensates are mixed polymers such as HDI trimers, pentamers, and heptamers. The polymer solution, delivered from the reactor system at a flow rate of 5000 kg / h and a temperature of 40°C, has a mass composition of approximately 45% HDI and approximately 55% HDI polymer. The polymer solution is pressurized to 4-5 barG by a booster pump and then enters the second barrel for heating by a second heating element. High-temperature thermal oil at 170-180°C is passed through the second heating element, heating the material from 40°C to 150-160°C. The fluid resides in the heating chamber for 3-4 minutes. The heated polymer solution is then sprayed directly into the first barrel through an atomizing nozzle for reduced-pressure flash evaporation. The pressure in the first barrel is 0.5-1 kPa(A). Vacuum is provided by a vacuum pump connected to the volatile outlet. In order to reduce the entrainment of mist, the gas in the first cylinder is equipped with a defoaming device. After a flash evaporation and concentration in the first cylinder, the polymer mass content is 92-95%;

[0056] After the first concentration, the polymer solution reaches the inner wall of the first cylinder under inertia. The concentrated fluid is evenly filmed under the rotating film scraping action of the film scraper. The film thickness is about 0.5-1mm. The first heating element outside the first cylinder is a hot oil jacket. The hot oil temperature is 170-180℃. The film scraper is driven by a motor with a speed of ~180RPM. There are comb-shaped teeth evenly arranged on the film scraper. The selected comb teeth are at an angle of 60° to the fluid flow direction (such as Figure 2 ). Finally, after deep evaporation, the volatile content of the polymer product in the fluid dropped to 1500 ppm, and the polymer did not show obvious degradation or decomposition.

[0057] Example 3

[0058] Compared to Example 1, the differences were as follows: the air inlet pipe of the interlayer chamber was closed and the atomizing nozzle was replaced with a single-channel nozzle; otherwise, the same procedures were followed as in Example 1. After a single flash concentration in the first barrel, the POE mass content of the polymer was 72-75%. Finally, after deep evaporation, the volatile matter (monomer and solvent) content of the polymer product in the fluid was reduced to 800-1200 ppm, and no significant degradation or decomposition of the polymer was observed.

[0059] Comparative Example 1

[0060] Compared with Example 1, the devolatilization system it adopts is as follows Figure 3 As shown (including a feed pump 301, a preheater 302, a first-stage strand devolatilization feed distributor 303, a first-stage strand devolatilizer 304, a first-stage volatile matter outlet 305, a first-stage concentrated liquid delivery pump 306, a second-stage strand preheater 307, a second-stage volatile matter outlet 308, a second-stage strand devolatilizer 309, a second-stage concentrated liquid delivery pump 310, and a second-stage concentrated liquid outlet 311), a POE polymer solution is devolatilized using two stages of conventional strand devolatilization equipment connected in series. The POE polymer solution treated is the same as that in Example 1.

[0061] The polymer solution is fed into the preheater 302 through the feed pump 301 and heated to 250-260°C, and then uniformly fed into the first-stage strip devolatilizer 304 (pressure 0.2-0.3 MPa (A)) through the first-stage strip devolatilization feed distributor 303 for devolatilization to obtain a first-stage concentrated liquid with a polymer mass content of 70-75%; the concentrated polymer solution is fed to the second-stage strip preheater 307 on the top of the second-stage strip devolatilizer 309 through the first-stage concentrated liquid delivery pump 306 and heated to ~275°C, and then enters the second-stage strip devolatilizer 309 (pressure 30-40 KPa (A)) for devolatilization, and finally the polymer product obtained through the second-stage concentrated liquid outlet 311 has a volatile matter content of ~0.8-1%.

[0062] Comparative Example 2

[0063] Compared with Example 1, the devolatilization system it adopts is as follows Figure 4 As shown (including a feed pump 401, a preheater 402, a first-stage flash devolatilizer 403, a first-stage flash volatile outlet 404, a first-stage concentrated liquid feed pump 405, a second-stage scraper preheater 406, a second-stage evaporation scraper 407, a second-stage scraper evaporator 408, a second-stage scraper volatile outlet 409, a second-stage concentrated product outlet 410, and a hot oil jacket 411), a conventional flash devolatilization device and a scraped film evaporation devolatilization device are connected in series to perform a POE polymer solution devolatilization treatment. The POE polymer solution treated is the same as that in Example 1.

[0064] The polymer solution is sent to the preheater 402 by the feed pump 401 and heated to 250-260°C, and then enters the first-level flash devolatilizer 403. The flash devolatilizer is adiabatic operation with a pressure of 0.1-0.3 MPa (A). After the first flash concentration, the polymer POE mass content is 40-45%; the volatile matter after flash evaporation exits the system through the first-level flash volatile matter outlet 404 and enters the subsequent solvent recovery unit. The first-level concentrated liquid is sent to the first-level concentrated liquid feed pump 405. The secondary scraper preheater 406 is preheated again to ~260℃ by the secondary scraper preheater 406 and then enters the secondary scraper evaporator 408 for secondary devolatilization. The secondary scraper evaporator 408 is equipped with a hot oil jacket 411 for heating. The hot oil temperature is ~290℃ and the operating pressure in the evaporator is 30~40KPa(A). The devolatilized volatile matter exits the system through the secondary scraper volatile matter outlet 409 and enters the subsequent solvent recovery unit. The concentrated liquid is discharged through the secondary concentrated product outlet 410.

[0065] After deep evaporation, the volatile matter (monomer and solvent) content in the polymer product in the fluid is about 3-5%, and the polymer is degraded or decomposed due to its long residence time in the system, and the polymer molecular weight is reduced by 6-8% compared with the polymer in the feed.

[0066] Each device or component involved in the present invention can adopt existing processing facilities, devices, or components with corresponding functions in the art, and a detailed description thereof is omitted. Any matters not specifically described herein are understood or known to those skilled in the art based on the existing technology, and a detailed description thereof is omitted. To highlight the concept of the present invention, many necessary equipment for industrial applications, such as pumps, valves, and control components, are omitted in the figures.

[0067] Obviously, the above embodiments of the present invention are merely examples for the purpose of illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not possible to enumerate all embodiments here. Any obvious variations or modifications arising from the technical solutions of the present invention are intended to fall within the spirit and scope of the present invention.

Claims

1. A fluid devolatilization apparatus comprising: A scraped film evaporator comprises a first cylinder and a scraper disposed within the first cylinder, the scraper being driven by a motor to rotate along the inner wall of the first cylinder to form a fluid film on the inner wall of the first cylinder; a first heating element is disposed on the outer wall of the first cylinder to provide heat required for evaporation of the fluid film; The heating liner comprises a second cylinder arranged in the first cylinder and a second heating element arranged in the second cylinder; Nozzles are evenly distributed on the surface of the second cylinder and are used to spray the heated liquid phase fluid in the second cylinder to the inner wall area of ​​the first cylinder covered by the scraper when it rotates; and A booster pump is used to pump the fluid to be devolatilized into the second cylinder for heating and provide the necessary pressure head for the fluid so that the fluid is in a superheated single liquid phase or liquid / liquid phase state after being heated by the heating element; The heating liner and the corresponding nozzle are used for static devolatilization.

2. The device according to claim 1, wherein The top of the first cylinder is provided with a volatile outlet, and the bottom is provided with a concentrated liquid outlet; The wall of the second cylinder is a sandwich structure to form a sandwich chamber in the sandwich.

3. The device according to claim 2, characterized in that The apparatus further comprises an air inlet pipe connected to the interlayer chamber and configured to input gas into the interlayer chamber; The nozzle is an atomizing nozzle, comprising a liquid inlet and a gas inlet, wherein the gas inlet is communicated with the interlayer chamber, and the liquid inlet is communicated with the interior of the second cylinder.

4. The device according to any one of claims 1 to 3, characterized in that The scraper is partially or completely provided with comb-shaped teeth on one side close to the inner wall of the first cylinder, and the angle α formed between the comb-shaped teeth and the central axis of the first cylinder is 30-75°.

5. The device according to claim 4, characterized in that The angle α formed between the comb-shaped toothed bar and the central axis of the first cylinder is 45-60°.

6. A method for devolatilizing a fluid using the apparatus according to any one of claims 1 to 5, comprising: (1) The superheated fluid in the second cylinder heated by the second heating element is ejected into the first cylinder through the nozzle under the action of the booster pump for flash evaporation to complete the primary concentration of the fluid; (2) The rotation of the scraper makes the fluid sprayed onto the inner wall of the first cylinder under inertia after completing the concentration to form a fluid film, and the residual volatile matter is further evaporated after being heated by the first heating element to obtain a deeply concentrated fluid.

7. The method according to claim 6, characterized in that When the nozzle of the device is an atomizing nozzle, the Henry's coefficient of the gas in the interlayer chamber in the volatile matter is greater than 40 MPa (A).

8. The method according to claim 7, characterized in that The Henry's coefficient of the gas in the interlayer chamber in the volatile matter is greater than 80 MPa(A).

9. The method according to claim 7, characterized in that The gas in the interlayer chamber is one or more of water vapor, air, nitrogen, argon, ethylene, propylene, methane, ethane, propane, hydrogen and carbon dioxide.

10. The method according to claim 8, characterized in that The gas in the interlayer chamber is nitrogen.

11. The method according to claim 7, characterized in that The atomizing nozzle draws the fluid in the second cylinder and the gas in the interlayer chamber into the nozzle at a mass ratio of 100:1 to 50:

1.

12. The method according to claim 10, characterized in that The atomizing nozzle draws the fluid in the second cylinder and the gas in the interlayer chamber into the nozzle at a mass ratio of 100:1 to 80:

1.

13. The method according to any one of claims 6 to 12, characterized in that The fluid is ejected from the nozzle at a velocity of 0.1 to 5 m / s; The pressure in the first cylinder does not exceed 1.5 MPa(A).

14. The method according to claim 13, characterized in that The fluid is ejected from the nozzle at a velocity of 0.3 to 3 m / s; The pressure in the first cylinder does not exceed 0.4 MPa(A).

15. The method according to claim 14, characterized in that The pressure in the first cylinder is 0.1-50 KPa(A).

16. The method according to any one of claims 6 to 12 and 14 to 15, characterized in that The film thickness of the scraper on the inner wall of the first cylinder is 0.1mm to 2mm; the first heating element is a hot fluid outer jacket, and the temperature of the heat medium in the jacket is 5 to 50°C higher than the temperature of the fluid on the inner wall of the first cylinder.

17. The method according to claim 16, characterized in that The temperature of the heat medium in the first heating element is 15-20° C. higher than the temperature of the fluid on the inner wall of the first cylinder.

18. The method according to any one of claims 6 to 12, 14 to 15 and 17, characterized in that The fluid is a polymer melt or a polymer solution, and the volatile components are solvents and / or monomers.

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