External heating type high-efficiency low-energy-consumption double-chamber esterification reaction device

Abstract

The invention discloses an external heating type high-efficiency low-energy-consumption double-chamber esterification reaction device, and aims to overcome the defects of complicated structure, non-uniform flow distribution, low esterification efficiency and high comprehensive energy consumption of an esterification reaction device in the prior art. According to the technical scheme, the device comprises a reaction kettle, a tubular heater, a short pipe, a U-shaped pipeline, a generated material outlet and an injection nozzle. A second material inlet is formed in the bottom of the tubular heater, a second material outlet is formed in the upper portion of the tubular heater, the interior of the reaction kettle is divided into an inner chamber and an outer chamber through an annular partition plate, the inner chamber is located between the outer side wall of the annular partition plate and the inner side wall of the reaction kettle, and the outer chamber is the space of the inner side wall of the annular partition plate and the space of the top of the annular partition plate. The inner chamber is communicated with the outer chamber, and materials are internally circulated among the heater, the reaction kettle, the short pipe and the U-shaped pipeline. The device has the advantages of simpler structure, short flow, uniform flow distribution, high esterification efficiency, low comprehensive energy consumption and the like.

Description

Technical Field

[0001] The invention relates to the technical field of polyester production, and more specifically to an externally heated, high-efficiency, low-energy-consumption double-chamber esterification reaction device. Background Art

[0002] The production of polyester is to mix the esterification reaction raw materials ethylene glycol (EG) and terephthalic acid (PTA) in a certain proportion in an esterification reactor (the molar ratio of EG / PTA in the first esterification reactor is about 1.65), under appropriate temperature and pressure conditions, and maintain sufficient time to complete the esterification reaction to produce ethylene terephthalate (BHET), and then synthesize polyethylene terephthalate, namely polyester (PET), through a condensation reaction.

[0003] There are two different types of existing esterification reactors. One is an internal circulation fully mixed esterification reactor, which is mainly composed of a cylindrical barrel, an internally extended agitator installed on the top of the barrel, a heated coil / tube bundle and a guide tube. Under the stirring action of the internal agitator, the material forms an up and down circulation of the material, the material is fully mixed, the heat transfer coefficient is enhanced and the rate of the esterification reaction is increased. This type of esterification reactor is usually used in series. The first reactor is mainly used for the dissolution of terephthalic acid (PTA), and the second reactor is mainly used to increase the esterification rate.

[0004] The internal circulation full mixed esterification reactor has the following shortcomings: First, the required reaction time is relatively long. The heat load of the first esterification reactor is the largest, and a corresponding heat transfer area is required. The number of heating coils inside the reactor is large, and the volume occupied by the reactor is large. The material covers the coil for a residence time of more than 4 hours. The extension of the reaction time will increase the amount of by-products generated, and due to the above-mentioned limitation on the reaction time, the optimization of the esterification process is limited. Second, the equipment is large in size, and it is difficult to manufacture, transport and hoist. Taking the 400t / d internal circulation full mixed esterification reactor as an example, the inner diameter of the cylinder has reached 4.6m. Third, its power consumption is large, which refers to the stirring power of the reactor and the power consumption of the coil heat medium delivery pump. Taking the 400t / d internal circulation full mixed esterification reactor as an example, the motor power of the stirring device and the coil heat medium delivery pump exceeds 150kW.

[0005] The other is the "external heating" esterification reactor, which is a series connection of a heater and a reactor in structure. The heater and the reactor are connected by a pipeline. Under the action of density difference, the material circulates internally between the heater and the reactor, and the water generated by the reaction enters the reactor together with ethylene glycol for removal. The "external heating" reactor is usually a self-circulating type, which forms a cycle by relying on the density difference of the material before and after entering the heater. The esterification temperature of the self-circulating reactor is about 285℃, and a very high EG / PTA slurry molar ratio (1.85-2.0) is used, the purpose is to further increase the density difference by evaporating a large amount of free EG. The "external heating" esterification reactor has the following shortcomings: a large amount of free EG evaporates in the esterification reactor, and this part of EG does not participate in the esterification reaction, resulting in a large amount of heat waste. There are many heat exchange tubes inside the heater, which can easily cause uneven flow distribution. The newly added EG / PTA slurry has a poor dispersion effect and is easy to cause mist entrainment.

[0006] The authorization announcement number is CN101613467B, and the patent name is: A hybrid polyester esterification reactor, including a heating reaction tank and an evaporation reaction tank, and also including a power mixing section, the outlet of the heating reaction tank is connected to the inlet of the evaporation reaction tank, the power mixing section is provided with a venturi tube and a power pump matched with the venturi tube, the inlet and outlet of the power mixing section are respectively connected to the outlet of the evaporation reaction tank and the inlet of the heating reaction tank, thereby forming a circulation channel for the material, and the venturi tube is provided with a suction port for introducing new slurry. The present invention utilizes the venturi tube to mix the slurry while sucking the slurry, which effectively improves the mixing effect, and at the same time combines the power pump and the heating power to effectively form the circulation of the slurry, so that the overall structure of the reactor is simpler, the operation is simpler, the material mixing is more uniform, and it is more conducive to the esterification reaction. The present invention is mainly used for the esterification reaction process of polyester. The defects of the above patent documents are: a power mixing section is provided to increase energy consumption; once the power pump fails seriously, it will cause the device to shut down.

[0007] Authorization announcement number CN212524113U, patent name: an external circulation multi-stage esterification reactor, the material flows through the plug flow inside the full mixing device between the two devices, achieving a greater degree of conversion of the reaction raw materials into reaction products, which is more conducive to the esterification reaction and obtains higher purity products. Disadvantages: the process is too long, the flow rate is easily unevenly distributed, it is difficult to discharge the material during shutdown, which easily leads to residual material and affects the product quality during startup.

[0008] The patent authorization announcement number is CN1248777C, and the patent name is: A container device for reaction or separation using external circulation heating, including a container and an external heat exchanger, and the container can be a tower or a kettle. The container is a double-chamber structure with an inner and outer chamber. The inner chamber is located at the bottom of the container, and the continuous space outside the inner and outer chambers in the container is the outer chamber. The top of the inner chamber is located below 1 / 2 of the height of the continuous space from the bottom of the container to the top. The pipe connection port connecting the container to the inlet of the heat exchanger is located at the bottom of the inner chamber and communicates with the inner chamber, and the pipe connection port connecting the container to the outlet of the heat exchanger is located at the bottom of the container and communicates with the outer chamber. The inner chamber and the outer chamber are isolated from each other, and the two are connected by a U-shaped tube as a channel for liquid materials. The esterification rate of this esterification reactor is generally only about 92%, which increases the burden on subsequent reactors. Summary of the invention

[0009] The present invention overcomes the shortcomings of the esterification reaction device in the prior art, such as complex structure, uneven flow distribution, low esterification efficiency and high comprehensive energy consumption, and provides an externally heated, high-efficiency and low-energy-consumption double-chamber esterification reaction device, which has the advantages of simpler structure, short process, uniform flow distribution, better mixing effect, high esterification efficiency, low comprehensive energy consumption and wide application range.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solution: a high-efficiency, external heat and low energy consumption double-chamber esterification reaction device, comprising: The tubular heater has a second material inlet and a second material outlet at the bottom and top, respectively; A reactor, wherein an annular partition is arranged inside the reactor, and the annular partition divides the reactor into an inner chamber and an outer chamber, wherein the inner chamber and the outer chamber are respectively located on the outer side wall and the inner side wall of the annular partition, a first material inlet is arranged on the side wall of the outer chamber, and a first material outlet is arranged at the bottom of the inner chamber; A U-shaped pipe, with two ends connected to the first material outlet and the second material inlet respectively, a generated material outlet is provided at the bottom of the U-shaped pipe, and a plurality of injection nozzles are provided in the circumferential direction at the end of the U-shaped pipe close to the second material inlet; The second material outlet and the first material inlet are connected via a connecting short pipe.

[0011] The present invention has a simple structure, no rotating equipment, a small size and light weight of a single piece of equipment, and is convenient to manufacture, process, transport, install and maintain. The key is low power consumption. The structural design of injecting the catalyst into the reactor at the bottom of the tubular heater accelerates the reaction rate of PTA and EG, reduces the heating temperature of the circulating material (the heating temperature is 260-270°C), and reduces heat consumption. The reactor is designed with a double-chamber and double-pressure structure to improve the equilibrium esterification rate. The structural design of injecting high-temperature esterified EG (>160°C) at the bottom of the tubular heater reduces the density of the circulating logistics inside the tubular heater, improves the circulation power of the circulating material, and reduces the heat consumption of the tubular heater.

[0012] Preferably, an anti-vortex baffle is provided at the second material inlet.

[0013] The anti-eddy current baffle can effectively prevent the eddy current from occurring when the material enters the tubular heater.

[0014] Preferably, a perforated disc type liquid distributor is provided at the end of the anti-vortex baffle away from the U-shaped pipe, and a plurality of liquid outlet holes are evenly distributed on the end surface of the perforated disc type liquid distributor.

[0015] A perforated plate liquid distributor is arranged at the bottom of the tubular heater to evenly distribute the material entering the tubular heater, thereby avoiding overheating of part of the circulating material inside the tubular heater and causing a decrease in product quality, thereby improving product quality.

[0016] Preferably, a gas phase outlet is provided at the top of the reactor.

[0017] The gas phase outlet is used for discharging steam.

[0018] Preferably, the reactor comprises a cylindrical body, an upper elliptical head and a lower elliptical head arranged at both ends of the cylindrical body.

[0019] Through the above structural arrangement, the reactor structure is made more compact and firm.

[0020] Preferably, a plurality of evenly distributed baffles are arranged between the top of the annular partition and the inner wall of the reactor in the circumferential direction, and the baffles are arranged obliquely.

[0021] The design of the welded baffles on the top of the reactor chamber not only enhances the mixing and dispersion effects of the materials, but also makes the distribution of the material flow more uniform and avoids dead corners in the material flow.

[0022] Preferably, convex shafts are provided at both ends of the baffle in the length direction, and the convex shafts at both ends are rotatably arranged on the inner wall of the reactor and the outer wall of the annular partition respectively; a tension spring is arranged between the baffle and the annular partition to pull the baffle to tilt; a pulling hole is arranged on the baffle, and a pull ring is arranged in the reactor, and the pull ring passes through several pulling holes of the baffle; several tensioners are arranged in the circumferential direction of the pulling ring, and the tensioner includes a long hollow tube and a pull rope arranged at the bottom of the long hollow tube, and the bottom of the pull rope is connected to the pull ring.

[0023] By setting up a long hollow tube, the inclination angle of the baffle 1-8 can be automatically adjusted as the slurry increases, which can prevent the slurry from spraying out and entraining mist, and can ensure the slurry spraying efficiency when there is too much slurry, thereby improving production efficiency.

[0024] Preferably, a vertically arranged hollow tube is provided in the reactor, the outer wall of the hollow tube and the inner wall of the reactor are connected via a mounting plate, the side wall of the hollow tube is provided with a plurality of through grooves, and the long cavity tube is arranged in the hollow tube.

[0025] The hollow tube plays the role of guiding the long hollow cavity tube so that the long hollow cavity tube can maintain a vertical state, and the buoyancy of the hollow tube can change with the change of the slurry.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention has a simple structure, no rotating equipment, a small size and light weight of a single piece of equipment, and is convenient to manufacture, transport, install and maintain. The key is low power consumption.

[0027] (2) The structural design of injecting the catalyst into the reactor at the bottom of the tubular heater accelerates the reaction rate of PTA and EG, reduces the heating temperature of the circulating material (the heating temperature is 260-270°C), and reduces heat consumption.

[0028] (3) The reactor of the present invention is designed with a double-chamber, double-pressure structure to improve the equilibrium esterification rate.

[0029] (4) The design of the welded baffle plate on the top of the reactor chamber of the present invention not only enhances the mixing and dispersion effect of the materials, but also makes the distribution of the material flow more uniform, avoiding dead corners of material flow.

[0030] (5) The material flowing through the baffle enters the inner chamber of the esterification kettle at a certain angle, which is beneficial to reduce the entrainment of EG steam.

[0031] (6) The reactor is designed with an annular baffle with holes inside. The material flows in from the outer chamber of the esterification reactor and then flows out from the inner chamber of the esterification reactor downward, forming an axial mixed flow. The circulating material flow is short, avoiding the situation where the material cannot be completely discharged during shutdown.

[0032] (7) The structural design of high-temperature esterified EG (>160℃) injected at the bottom of the tubular heater reduces the density of the circulating flow inside the tubular heater, improves the circulation power of the circulating material, and reduces the heat consumption of the tubular heater.

[0033] (8) A perforated plate liquid distributor is installed at the bottom of the tubular heater to ensure that the material entering the tubular heater is evenly distributed, thereby avoiding overheating of part of the circulating material inside the tubular heater, which may lead to a decrease in product quality and improve product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a structural schematic diagram of a reaction kettle of the present invention; Figure 3 yes Figure 2 The cross-sectional view in the AA direction; Figure 4 It is a schematic diagram of the structure of the liquid distribution holes of the orifice plate of the present invention; Figure 5 It is a schematic diagram of the structure of the baffle of the present invention; Figure 6 is a front view of the injection nozzle of the present invention; Figure 7 : is a top view of the injection nozzle of the present invention Figure 8 is a schematic structural diagram of a reaction kettle in a second embodiment of the present invention; Fig. 9 yes Figure 8 Schematic diagram of the structure of the C region; Fig.10 yes Figure 8 Schematic diagram of the structure of the D region in FIG. Fig.11 yes Figure 8 Cross-sectional view in the BB direction; Fig.12 yes Fig.11 A partial enlarged view of Fig.13 is a schematic structural diagram of a baffle in a second embodiment of the present invention; In the figure: 1, reactor, 1-1, upper elliptical head, 1-2, lower elliptical head, 1-3, cylindrical body, 1-4, annular partition, 1-5, inner chamber, 1-6, outer chamber, 1-7, gas phase outlet, 1-8, baffle, 1-9, first material outlet, 1-10, first material inlet, 1-11, convex shaft, 1-12, tension spring, 1-13, pulling hole, 1-14, pull ring, 1-15, long cavity tube, 1-16, pull rope, 1-17, hollow tube, 1-18, through groove; 2. Tubular heater, 2-1. Second material inlet, 2-2. Second material outlet, 2-3. Anti-eddy current baffle, 2-4. Perforated plate liquid distributor; 3. Short pipe, 4. U-shaped pipe, 5. Material generation outlet, 6. Injection nozzle. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example 1: Reference Figures 1 to 7As shown, an externally heated high-efficiency, low-energy consumption double-chamber esterification reaction device comprises: a reactor 1, a tubular heater 2, a short tube 3, a U-shaped pipe 4, a generated material outlet 5 and an injection nozzle 6. The bottom of the tubular heater 2 is provided with a second material inlet 2-1, and the upper part of the tubular heater 2 is provided with a second material outlet 2-2. The interior of the reactor 1 is divided into the inner chamber 1-5 and the outer chamber 1-6 by an annular partition 1-4. The inner chamber 1-5 is located between the outer side wall of the annular partition 1-4 and the inner side wall of the reactor 1. The outer chamber 1-6 is the space of the inner side wall of the annular partition 1-4 and the space on the top of the annular partition 1-4. The inner chamber 1-5 and the outer chamber 1-6 are connected. The cylindrical barrel of the inner chamber 1-5 of the reactor 1 A first material inlet 1-10 is provided on the body 1-3, a first material outlet 1-9 is provided at the bottom of the lower elliptical head 1-2 of the outer chamber 1-6 of the reactor 1, a second material outlet 2-2 of the tubular heater 2 is connected to the first material inlet 1-10 of the inner chamber 1-5 through a connecting short tube 3, and a second material inlet 2-1 of the tubular heater 2 is connected to the first material outlet 1-9 of the outer chamber 1-6 of the reactor through the U-shaped pipe 4, and the material is circulated internally among the heater 2, the reactor 1, the short pipe 3 and the U-shaped pipe 4.

[0036] The reactor 1 is composed of the upper elliptical head 1-1, the lower elliptical head 1-2 and the cylindrical body 1-3. The lower elliptical head 1-2 is welded to the bottom of the cylindrical body 1-3, and the upper elliptical head 1-1 is welded to the top of the cylindrical body 1-3. The side wall of the upper head 1-1 is provided with a gas phase outlet 1-7, the bottom side wall of the lower head 1-2 is provided with the first material outlet 1-9, and the first material inlet 1-10 connected to the inner chamber 1-5 is provided at a position of the cylindrical body 1-3 near the lower elliptical head 1-2.

[0037] The interior of the cylindrical body 1-3 is divided into two parts, the inner chamber 1-5 and the outer chamber 1-6, by the annular partition 1-4. The annular partition 1-4 is concentrically arranged with the cylindrical body 1-3. The outer chamber 1-6 is a jacket structure. The top of the inner chamber 1-5 is communicated with the outer chamber 1-6. The first material inlet 1-10 is communicated with the inner chamber 1-5, and the first material outlet 1-10 is communicated with the inner chamber 1-5.

[0038] The annular partition 1-4 is provided with a small number of openings, and the installation height of the annular partition 1-4 does not exceed 1 / 2 of the height of the cylindrical body 1-3.

[0039] The bottom of the annular partition plate 1-4 is connected to the lower elliptical head 1-2 by welding, and a material discharge port is also provided at the welding point between the bottom of the annular partition plate 1-4 and the lower elliptical head 1-2.

[0040] The top of the annular partition 1-4 is provided with baffles 1-8 evenly distributed in the circumferential direction, and the two ends of the baffles 1-8 in this embodiment are respectively welded to the cylindrical barrel 1-3 and the annular partition 1-4. The design of the baffles 1-8 allows the slurry to flow through the baffles 1-8 when it flows out from the top of the inner chamber 1-5, so that the material forms a spiral flow, effectively preventing the slurry from rushing out vertically and reducing the excessive aerosol entrainment of the slurry.

[0041] The tubular heater 2 is installed vertically, the material flows through the tube side, the heating medium flows through the shell side, and the heating medium is generated in the gas phase.

[0042] The bottom end cap of the tubular heater 2 is provided with a second material inlet 2-1. The second material inlet 2-1 at the bottom of the tubular heater 2 is provided with an anti-vortex baffle 2-3 and a perforated liquid distributor 2-4. The anti-vortex baffle 2-3 is arranged in the vertical direction to play a blocking role to prevent the material from generating vortexes when entering the tubular heater 2. The end surface of the perforated liquid distributor 2-4 is evenly distributed with a number of liquid outlets, so that the material can enter the interior of the tubular heater 2 more evenly when passing through the perforated liquid distributor 2-4. The second material inlet 2-1 of the tubular heater 2 is connected to the U-shaped pipe 4. The top of the tubular heater 2 is provided with a second material outlet 2-2. The second material outlet 2-2 of the tubular heater 2 is connected to the first inlet 1-10 of the outer chamber 1-6 through the connecting short pipe 3.

[0043] The U-shaped pipe 4 is a jacket structure, and the U-shaped pipe is heated by gas phase conduction.

[0044] The bottom of the U-shaped pipe 4 is provided with a plurality of product outlets 5 .

[0045] Four evenly distributed injection nozzles 6 are provided on the upper part of the vertical tube of the U-shaped pipe 4 at the lower part of the tubular heater 2. The axes of the four injection nozzles 6 are on the same horizontal plane. The axes of the four injection nozzles 6 form a regular quadrilateral with a side length equal to the radius of the U-shaped tube 4.

[0046] The working principle of the present invention is as follows, taking two operation schemes as examples, namely operation scheme 1 and operation scheme 2.

[0047] Operation plan 1: The esterified EG and the recycled EG from the reactor 1 are mixed with terephthalic acid PTA to form a slurry with a molar ratio of 1.6:1, and a certain proportion of catalyst is added to the EG / PTA slurry.

[0048] According to the production demand, EG / PTA slurry mixed with a certain proportion of catalyst is injected into the U-shaped pipe 4 from four injection nozzles 6 at a certain flow rate. A large amount of free EG in the EG / PTA slurry is heated and vaporized in the tubular heater 2, and the density of the EG / PTA slurry is reduced, which provides power for the EG / PTA slurry to flow through the tubular heater 2. The temperature of the second outlet 2-2 of the material of the tubular heater 2 is controlled to be 260-270°C, and the tubular heater 2 is heated by gas phase conduction.

[0049] The esterification product, byproduct water, PTA and free EG from the tubular heater 2 enter the inner chamber 1-5 of the reactor 1 through the connecting short tube 3. The temperature of the reactor is 260-270°C, and the pressure of the inner chamber 1-5 of the reactor 1 is about 0.02MPa. The material flows through the baffle 1-8 and enters the outer chamber 1-6 of the reactor 1. The pressure of the outer chamber 1-6 of the reactor 1 is slightly positive. PTA and EG continue to undergo esterification reaction in the outer chamber 1-6 of the reactor 1. The byproduct water and part of the unreacted ethylene glycol EG are flash-evaporated and separated in the outer chamber 1-6 of the reactor 1, and discharged in the form of steam through the gas phase outlet 1-7 on the reactor 1. The mixed steam enters the subsequent separation tower for separation.

[0050] The esterification product, incompletely reacted PTA and EG flow into the U-shaped pipe 4 , are mixed with the EG / PTA slurry injected from the injection nozzle 6 , and then enter the tubular heater 2 .

[0051] The esterification product flows out from the esterification product outlet 5 located at the bottom of the U-shaped pipe 4 and is pumped into the subsequent polycondensation reactor. It should be noted that the four injection nozzles can inject the same material (EG / PTA slurry), different materials (EG / PTA slurry, esterified EG, catalyst and other additives), or a mixture of multiple materials (EG / PTA slurry + esterified EG + catalyst). Multi-point injection of EG / PTA slurry is conducive to the mixing and dispersion of the injected material and the circulating material. It is more energy-efficient to directly inject the esterified EG into the U-tube without cooling.

[0052] Run Solution 2: The recycled EG and terephthalic acid (PTA) are prepared into a slurry with a molar ratio of about 1.2:1.

[0053] According to the production demand, EG / PTA slurry is injected into the U-shaped pipe 4 from the injection nozzle 6 at a certain flow rate, and the esterified EG and catalyst from the reactor 1 are injected into the U-shaped pipe 4 from the injection nozzle 6 at a certain ratio. The molar ratio of recycled EG and esterified EG to PTA is about 1.6:1.

[0054] The EG / PTA slurry is heated and vaporized in the tubular heater 2, and the temperature of the outlet 2-2 of the tubular heater is controlled to be 260-270°C. The tubular heater 2 is heated by gas phase conduction.

[0055] The esterification product, byproduct water, PTA and free EG from the tubular heater 2 enter the inner chamber 1-5 of the reactor 1 through the connecting short tube 3. The temperature of the reactor is 260-270°C, and the pressure of the inner chamber 1-5 of the reactor 1 is about 0.02MPa. The material flows through the baffle 1-8 and enters the outer chamber 1-6 of the reactor 1. The pressure of the outer chamber 1-6 of the reactor 1 is slightly positive. PTA and EG continue to undergo esterification reaction in the outer chamber 1-6 of the reactor 1. The byproduct water and part of the unreacted ethylene glycol EG are flash-evaporated and separated in the outer chamber 1-6 of the reactor 1, and discharged in the form of steam through the gas phase outlet 1-7 on the reactor 1. The mixed steam enters the subsequent separation tower for separation.

[0056] The esterification product, incompletely reacted PTA and EG flow into the U-shaped pipe 4 , are mixed with the EG / PTA slurry, esterified EG and catalyst injected from the injection nozzle 6 , and then enter the tubular heater 2 .

[0057] The esterification product flows out from the esterification product outlet 5 located at the bottom of the U-shaped pipe 4 and is pumped into the subsequent polycondensation reactor.

[0058] It should be noted that the four injection nozzles can inject the same material (EG / PTA slurry), different materials (EG / PTA slurry, esterified EG, catalyst and other additives), or a mixture of multiple materials (EG / PTA slurry + esterified EG + catalyst). Multi-point injection of EG / PTA slurry is conducive to the mixing and dispersion of the injected material and the circulating material. It is more energy-efficient to directly inject the esterified EG into the U-tube without cooling.

[0059] Compared with the prior art, the present invention is more energy-efficient, mainly because, compared with the prior art, the stirring motor is omitted. The power of the internal circulation of the present invention is mainly injected with ethylene glycol EG through a nozzle. After EG is gasified, its density decreases, resulting in a thermal siphon phenomenon. No external power is required, forming a self-circulation.

[0060] Example 2: Reference Figure 1 , Figures 7 to 13As shown, an externally heated high-efficiency, low-energy consumption double-chamber esterification reaction device comprises: a reactor 1, a tubular heater 2, a short tube 3, a U-shaped pipe 4, a generated material outlet 5 and an injection nozzle 6. The bottom of the tubular heater 2 is provided with a second material inlet 2-1, and the upper part of the tubular heater 2 is provided with a second material outlet 2-2. The interior of the reactor 1 is divided into the inner chamber 1-5 and the outer chamber 1-6 by an annular partition 1-4. The inner chamber 1-5 is located between the outer side wall of the annular partition 1-4 and the inner side wall of the reactor 1. The outer chamber 1-6 is the space of the inner side wall of the annular partition 1-4 and the space on the top of the annular partition 1-4. The inner chamber 1-5 and the outer chamber 1-6 are connected. The cylindrical barrel of the inner chamber 1-5 of the reactor 1 A first material inlet 1-10 is provided on the body 1-3, a first material outlet 1-9 is provided at the bottom of the lower elliptical head 1-2 of the outer chamber 1-6 of the reactor 1, a second material outlet 2-2 of the tubular heater 2 is connected to the first material inlet 1-10 of the inner chamber 1-5 through a connecting short tube 3, and a second material inlet 2-1 of the tubular heater 2 is connected to the first material outlet 1-9 of the outer chamber 1-6 of the reactor through the U-shaped pipe 4, and the material is circulated internally among the heater 2, the reactor 1, the short pipe 3 and the U-shaped pipe 4.

[0061] The reactor 1 is composed of the upper elliptical head 1-1, the lower elliptical head 1-2 and the cylindrical body 1-3. The lower elliptical head 1-2 is welded to the bottom of the cylindrical body 1-3, and the upper elliptical head 1-1 is welded to the top of the cylindrical body 1-3. The side wall of the upper head 1-1 is provided with a gas phase outlet 1-7, the bottom side wall of the lower head 1-2 is provided with the first material outlet 1-9, and the first material inlet 1-10 connected to the inner chamber 1-5 is provided at a position of the cylindrical body 1-3 near the lower elliptical head 1-2.

[0062] The interior of the cylindrical body 1-3 is divided into two parts, the inner chamber 1-5 and the outer chamber 1-6, by the annular partition 1-4. The annular partition 1-4 is concentrically arranged with the cylindrical body 1-3. The outer chamber 1-6 is a jacket structure. The top of the inner chamber 1-5 is communicated with the outer chamber 1-6. The first material inlet 1-10 is communicated with the inner chamber 1-5, and the first material outlet 1-10 is communicated with the inner chamber 1-5.

[0063] The annular partition 1-4 is provided with a small number of openings, and the installation height of the annular partition 1-4 does not exceed 1 / 2 of the height of the cylindrical body 1-3.

[0064] The bottom of the annular partition plate 1-4 is connected to the lower elliptical head 1-2 by welding, and a material discharge port is also provided at the welding point between the bottom of the annular partition plate 1-4 and the lower elliptical head 1-2.

[0065] The top of the annular partition 1-4 is provided with baffles 1-8 evenly distributed in the circumferential direction, and the two ends of the baffles 1-8 in this embodiment are rotatably connected to the cylindrical body 1-3 and the annular partition 1-4 respectively.

[0066] Convex shafts 1-11 are provided at both ends of the baffle in the length direction, and the convex shafts 1-11 at both ends are rotatably arranged on the inner wall of the reactor 1 and the outer wall of the annular partition 1-4 respectively; a tension spring 1-12 for pulling the baffle 1-8 to tilt is provided between the baffle 1-8 and the annular partition 1-4; a pulling hole 1-13 is provided on the baffle 1-8, and a pull ring 1-14 is provided in the reactor, and the pull ring 1-14 is passed through the pulling holes 1-13 of several baffles 1-8; several tensioners are provided in the circumferential direction of the pulling ring. In this embodiment, two tensioners are provided, and different numbers can be selected and set according to actual needs. The tensioner includes a long hollow tube 1-15 and a pull rope 1-16 arranged at the bottom of the long hollow tube 1-15, and the bottom of the pull rope 1-16 is connected to the pull ring 1-14. A vertically arranged hollow tube 1-17 is arranged in the reactor 1, and the outer wall of the hollow tube 1-17 and the inner wall of the reactor 1 are connected by a mounting plate 1-18. The side wall of the hollow tube 1-17 is provided with a plurality of through grooves 1-18. A long hollow tube 1-15 is arranged in the hollow tube 1-17. The diameter of the inner cavity of the hollow tube 1-17 is larger than the outer diameter of the long hollow tube 1-15. The hollow tube 1-17 plays a role in guiding the long hollow tube 1-15 so that the long hollow tube 1-15 can maintain a vertical state.

[0067] When there is not much slurry in the reactor 1, the long hollow tube 1-15 is not submerged by the slurry, or the submerged volume is small, and the buoyancy generated by the long hollow tube 1-15 is small. At this time, the baffle 1-8 is acted upon by the tension spring 1-12, and the baffle 1-8 maintains the maximum inclination angle. When the material flows out of the baffle 1-8, the slurry forms a spiral flow, which effectively prevents the slurry from rushing out vertically and reduces the excessive aerosol entrainment of the slurry.

[0068] As the internal slurry increases, the volume of the long hollow tube 1-15 submerged in the slurry increases, and the upward buoyancy of the long hollow tube 1-15 also increases. The long hollow tube 1-15 overcomes the elastic force of the tension spring 1-12 through the pull rope 1-16, so that the pull ring 1-14 moves upward, and the pull ring 1-14 drives the baffle 1-8, so that the inclination angle of the baffle 1-8 gradually decreases (that is, rotates in the vertical direction). At this time, due to the increase of slurry, the baffle 1-8 does not need to maintain a large inclination angle. By reducing the inclination angle of the baffle 1-8, the flow area of ​​the slurry is increased, and the production efficiency is improved. Although the slurry will be sprayed vertically, due to the increase of slurry, the sprayed slurry will be covered by the upper slurry, which can also reduce the entrainment of mist. That is to say, when there is little slurry, the baffle 1-8 can be tilted at a large angle, so that the slurry forms a spiral flow, effectively preventing the slurry from rushing out vertically and reducing the excessive aerosol entrainment of the slurry. As the slurry increases, the angle of the baffle 1-8 can be automatically adjusted, and the inclination angle of the baffle 1-8 gradually decreases, so as to increase the efficiency of slurry spraying and improve production efficiency. Therefore, by providing the long hollow cavity tube 1-15, the inclination angle of the baffle 1-8 can be automatically adjusted as the slurry increases, which can prevent the slurry from spraying out and entraining aerosol, and can ensure the slurry spraying efficiency when there is too much slurry, thereby improving production efficiency.

[0069] The tubular heater 2 is installed vertically, the material flows through the tube side, the heating medium flows through the shell side, and the heating medium is generated in the gas phase.

[0070] The bottom end cap of the tubular heater 2 is provided with a second material inlet 2-1. The second material inlet 2-1 at the bottom of the tubular heater 2 is provided with an anti-vortex baffle 2-3 and a perforated liquid distributor 2-4. The anti-vortex baffle 2-3 is arranged in the vertical direction to play a blocking role to prevent the material from generating vortexes when entering the tubular heater 2. The end surface of the perforated liquid distributor 2-4 is evenly distributed with a number of liquid outlets, so that the material can enter the interior of the tubular heater 2 more evenly when passing through the perforated liquid distributor 2-4. The second material inlet 2-1 of the tubular heater 2 is connected to the U-shaped pipe 4. The top of the tubular heater 2 is provided with a second material outlet 2-2. The second material outlet 2-2 of the tubular heater 2 is connected to the first inlet 1-10 of the outer chamber 1-6 through the connecting short pipe 3.

[0071] The U-shaped pipe 4 is a jacket structure, and the U-shaped pipe is heated by gas phase conduction.

[0072] The bottom of the U-shaped pipe 4 is provided with a plurality of product outlets 5 .

[0073] Four evenly distributed injection nozzles 6 are provided on the upper part of the vertical tube of the U-shaped pipe 4 at the lower part of the tubular heater 2. The axes of the four injection nozzles 6 are on the same horizontal plane. The axes of the four injection nozzles 6 form a regular quadrilateral with a side length equal to the radius of the U-shaped tube 4.

[0074] The working principle of the present invention is as follows, taking two operation schemes as examples, namely operation scheme 1 and operation scheme 2.

[0075] Operation plan 1: The esterified EG and the recycled EG from the reactor 1 are mixed with terephthalic acid PTA to form a slurry with a molar ratio of 1.6:1, and a certain proportion of catalyst is added to the EG / PTA slurry.

[0076] According to the production demand, EG / PTA slurry mixed with a certain proportion of catalyst is injected into the U-shaped pipe 4 from four injection nozzles 6 at a certain flow rate. A large amount of free EG in the EG / PTA slurry is heated and vaporized in the tubular heater 2, and the density of the EG / PTA slurry is reduced, which provides power for the EG / PTA slurry to flow through the tubular heater 2. The temperature of the second outlet 2-2 of the material of the tubular heater 2 is controlled to be 260-270°C, and the tubular heater 2 is heated by gas phase conduction.

[0077] The esterification product, byproduct water, PTA and free EG from the tubular heater 2 enter the inner chamber 1-5 of the reactor 1 through the connecting short tube 3. The temperature of the reactor is 260-270°C, and the pressure of the inner chamber 1-5 of the reactor 1 is about 0.02MPa. The material flows through the baffle 1-8 and enters the outer chamber 1-6 of the reactor 1. The pressure of the outer chamber 1-6 of the reactor 1 is slightly positive. PTA and EG continue to undergo esterification reaction in the outer chamber 1-6 of the reactor 1. The byproduct water and part of the unreacted ethylene glycol EG are flash-evaporated and separated in the outer chamber 1-6 of the reactor 1, and discharged in the form of steam through the gas phase outlet 1-7 on the reactor 1. The mixed steam enters the subsequent separation tower for separation.

[0078] The esterification product, incompletely reacted PTA and EG flow into the U-shaped pipe 4 , are mixed with the EG / PTA slurry injected from the injection nozzle 6 , and then enter the tubular heater 2 .

[0079] The esterification product flows out from the esterification product outlet 5 at the bottom of the U-shaped pipe 4 and is pumped into the subsequent polycondensation reactor. It should be noted that the four injection nozzles can inject the same material (EG / PTA slurry), different materials (EG / PTA slurry, esterified EG, catalyst and other additives), or a mixture of multiple materials (EG / PTA slurry + esterified EG + catalyst). Multi-point injection of EG / PTA slurry is conducive to the mixing and dispersion of the injected material and the circulating material. It is more energy-efficient to directly inject the esterified EG into the U-tube without cooling.

[0080] Run Solution 2: The recycled EG and terephthalic acid (PTA) are prepared into a slurry with a molar ratio of about 1.2:1.

[0081] According to the production demand, EG / PTA slurry is injected into the U-shaped pipe 4 from the injection nozzle 6 at a certain flow rate, and the esterified EG and catalyst from the reactor 1 are injected into the U-shaped pipe 4 from the injection nozzle 6 at a certain ratio. The molar ratio of recycled EG and esterified EG to PTA is about 1.6:1.

[0082] The EG / PTA slurry is heated and vaporized in the tubular heater 2, and the temperature of the outlet 2-2 of the tubular heater is controlled to be 260-270°C. The tubular heater 2 is heated by gas phase conduction.

[0083] The esterification product, byproduct water, PTA and free EG from the tubular heater 2 enter the inner chamber 1-5 of the reactor 1 through the connecting short tube 3. The temperature of the reactor is 260-270°C, and the pressure of the inner chamber 1-5 of the reactor 1 is about 0.02MPa. The material flows through the baffle 1-8 and enters the outer chamber 1-6 of the reactor 1. The pressure of the outer chamber 1-6 of the reactor 1 is slightly positive. PTA and EG continue to undergo esterification reaction in the outer chamber 1-6 of the reactor 1. The byproduct water and part of the unreacted ethylene glycol EG are flash-evaporated and separated in the outer chamber 1-6 of the reactor 1, and discharged in the form of steam through the gas phase outlet 1-7 on the reactor 1. The mixed steam enters the subsequent separation tower for separation.

[0084] The esterification product, incompletely reacted PTA and EG flow into the U-shaped pipe 4 , are mixed with the EG / PTA slurry, esterified EG and catalyst injected from the injection nozzle 6 , and then enter the tubular heater 2 .

[0085] The esterification product flows out from the esterification product outlet 5 located at the bottom of the U-shaped pipe 4 and is pumped into the subsequent polycondensation reactor.

[0086] It should be noted that the four injection nozzles can inject the same material (EG / PTA slurry), different materials (EG / PTA slurry, esterified EG, catalyst and other additives), or a mixture of multiple materials (EG / PTA slurry + esterified EG + catalyst). Multi-point injection of EG / PTA slurry is conducive to the mixing and dispersion of the injected material and the circulating material. It is more energy-efficient to directly inject the esterified EG into the U-tube without cooling.

[0087] Compared with the prior art, the present invention is more energy-efficient, mainly because, compared with the prior art, the stirring motor is omitted. The power of the internal circulation of the present invention is mainly injected with ethylene glycol EG through a nozzle. After EG is gasified, its density decreases, resulting in a thermal siphon phenomenon. No external power is required, forming a self-circulation.

[0088] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. An externally heated, high-efficiency, low-energy-consumption dual-chamber esterification reaction device, characterized in that: include: The tubular heater has a second material inlet and a second material outlet at the bottom and top, respectively; A reactor, wherein an annular partition is arranged inside the reactor, and the annular partition divides the reactor into an inner chamber and an outer chamber, wherein the inner chamber and the outer chamber are respectively located on the outer side wall and the inner side wall of the annular partition, a first material inlet is arranged on the side wall of the outer chamber, and a first material outlet is arranged at the bottom of the inner chamber; A U-shaped pipe, with two ends connected to the first material outlet and the second material inlet respectively, a generated material outlet is provided at the bottom of the U-shaped pipe, and a plurality of injection nozzles are provided in the circumferential direction at the end of the U-shaped pipe close to the second material inlet; The second material outlet and the first material inlet are connected via a connecting short pipe.

2. The externally heated high-efficiency, low-energy consumption dual-chamber esterification reaction device according to claim 1 is characterized in that: An anti-vortex baffle is provided at the second material inlet.

3. The externally heated high-efficiency, low-energy consumption dual-chamber esterification reaction device according to claim 2 is characterized in that: A perforated disc type liquid distributor is arranged at the end of the anti-eddy current baffle away from the U-shaped pipe, and a plurality of liquid outlet holes are evenly distributed on the end surface of the perforated disc type liquid distributor.

4. The externally heated high-efficiency, low-energy consumption dual-chamber esterification reaction device according to claim 1 is characterized in that: A gas phase outlet is arranged on the top of the reactor.

5. The externally heated high-efficiency, low-energy consumption dual-chamber esterification reaction device according to any one of claims 1 to 4, characterized in that: The reaction kettle comprises a cylindrical body, an upper elliptical head and a lower elliptical head arranged at two ends of the cylindrical body.

6. The externally heated high-efficiency, low-energy consumption dual-chamber esterification reaction device according to any one of claims 1 to 4, characterized in that: A plurality of evenly distributed baffles are arranged between the circumferential direction of the top of the annular partition and the inner side wall of the reactor, and the baffles are arranged obliquely.

7. The externally heated high-efficiency, low-energy consumption dual-chamber esterification reaction device according to claim 6 is characterized in that: Convex shafts are provided at both ends of the baffle in the length direction, and the convex shafts at both ends are rotatably arranged on the inner wall of the reactor and the outer wall of the annular partition respectively; a tension spring is arranged between the baffle and the annular partition to pull the baffle to tilt; a pulling hole is arranged on the baffle, and a pulling ring is arranged in the reactor, and the pulling ring passes through several pulling holes of the baffle; several tensioners are arranged in the circumferential direction of the pulling ring, and the tensioner includes a long hollow tube and a pulling rope arranged at the bottom of the long hollow tube, and the bottom of the pulling rope is connected to the pulling ring.

8. The externally heated high-efficiency, low-energy consumption dual-chamber esterification reaction device according to claim 7 is characterized in that: A vertically arranged hollow tube is arranged in the reactor, the outer wall of the hollow tube and the inner wall of the reactor are connected through a mounting plate, a plurality of through grooves are arranged on the side wall of the hollow tube, and a long cavity tube is arranged in the hollow tube.

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