CN118767821A - An ultra-high molecular weight polyethylene reactor - Google Patents

Abstract

The invention provides an ultra-high molecular weight polyethylene reaction kettle, belongs to the technical field of polyethylene production, and solves the problem that the reaction cannot be normally carried out due to untimely heat removal in the prior art. The cold baffle tube comprises a barrel, sealing heads are arranged at the upper end and the lower end of the barrel, an inner jacket is arranged on the inner wall of the barrel, a water inlet pipe and a water outlet pipe penetrating through the side wall of the barrel are connected with the inner jacket, a finger-shaped inner cold baffle tube is vertically arranged in the barrel, the finger-shaped inner cold baffle tube comprises an outer tube and finger-shaped rods arranged on the outer wall of the outer tube, an inner tube is arranged on the inner side of the outer tube, a plurality of groups of water inlet pipes and water outlet pipes are arranged, and a guide plate is arranged in the inner jacket. The inner jacket is arranged on the inner wall of the cylinder body, so that the heat transfer efficiency of polyethylene is effectively prevented from being influenced by the excessive wall thickness of the cylinder body, and the finger-shaped inner cold baffle pipe is added with circulating cooling water for assisting in cooling, so that heat in the production process is timely conveyed out of the reaction kettle, the reaction can be effectively ensured to be normally carried out at a proper temperature, and the polyethylene with ultra-high molecular weight can be produced.

Description

An ultra-high molecular weight polyethylene reactor

Technical Field

The invention belongs to the technical field of polyethylene production, in particular to an ultra-high molecular weight polyethylene reactor.

Background Art

Ultra-high molecular weight polyethylene (molecular weight 1-6 million) is a thermoplastic engineering plastic with excellent comprehensive properties. Common methods for producing ultra-high molecular weight polyethylene include Mitsui low-pressure slurry method, Solvay method, and U.C.C gas phase method, among which the low-pressure slurry method is the most important method. The low-pressure slurry method is that the gaseous ethylene introduced from the boundary area is depressurized and enters the ethylene preheater, heated by medium-pressure steam and controlled to add the hydrocarbon steam circulation pipeline, and then the ethylene enters the reactor and undergoes polymerization reaction under the action of the catalyst to form a slurry-like substance.

A large amount of heat will be generated during the above-mentioned polymerization reaction. In order to ensure that the reaction is carried out at a suitable temperature, an external jacket will be set on the outside of the reactor for heat exchange. Due to the low heat transfer coefficient of the external jacket and the poor heat exchange effect, it is necessary to use external circulation or add hexane to evaporate and remove the heat. In the production process of ultra-high molecular weight polyethylene, the concentration of slurry and catalyst in the reactor is high, and the hexane heat is not removed in time, the product will swell, explode, agglomerate, and settle. The overflow outlet, external circulation pipeline and heat exchanger will be blocked. At the same time, the catalyst inlet pipe is also easily blocked, making production impossible. Based on the above problems, the existing ultra-high molecular weight polyethylene reactor cannot produce polyethylene with a higher molecular weight (molecular weight 6-10 million), because the production of ultra-high molecular weight polyethylene requires reducing the reaction pressure and reaction temperature, the reaction time will be prolonged, causing the catalyst to settle, and it is easier to block the pipeline.

Summary of the invention

In view of the above problems, the purpose of the present invention is to provide an ultra-ultra-high molecular weight polyethylene reactor, in which an inner jacket is arranged on the inner wall of the cylinder to effectively prevent the cylinder wall thickness from being too thick and affecting the heat transfer efficiency of the polyethylene, and circulating cooling water is introduced into the finger-shaped internal cooling pipe to assist in cooling, so that the heat in the production process can be transported out of the reactor in time, which can effectively ensure that the reaction proceeds normally at a suitable temperature, thereby producing ultra-ultra-high molecular weight polyethylene.

The technical solution adopted by the present invention is as follows:

An ultra-ultra-high molecular weight polyethylene reactor comprises a cylinder, wherein both upper and lower ends of the cylinder are provided with end caps, an inner jacket is provided on the inner wall of the cylinder, the inner jacket is connected with a water inlet pipe and a water outlet pipe penetrating the side wall of the cylinder, a finger-shaped inner cooling baffle is vertically arranged in the cylinder, the finger-shaped inner cooling baffle comprises an outer tube and a finger-shaped rod arranged on the outer wall of the outer tube, an inner tube is arranged on the inner side of the outer tube and the bottom of the inner tube is communicated with the outer tube, a plurality of groups of water inlet pipes and water outlet pipes are provided, and a guide plate is arranged in the inner jacket.

Preferably, half-tube jackets are provided on the outer walls of the two heads.

Preferably, the cylinder is provided with a downwardly inclined overflow discharge pipe and an upwardly inclined catalyst feed pipe.

Preferably, the overflow discharge pipe and the catalyst feed pipe are both provided with flushing pipes.

Preferably, a plate-and-frame agitator is arranged in the cylinder, the plate-and-frame agitator is connected to a vertically arranged agitator shaft, the agitator shaft is connected to a agitator transmission device, and the agitator transmission device is installed on the head above the cylinder.

Preferably, both of the sealing heads are provided with quick-opening manholes.

Preferably, the head located above the cylinder is connected to a vertically arranged multi-stage telescopic rod, the telescopic end of the multi-stage telescopic rod is connected to an annular plate, an annular water channel is arranged in the annular plate, a water inlet joint connected to the annular water channel is connected to the annular plate, a plurality of first nozzles connected to the annular water channel are arranged on the inner wall of the annular plate, and a plurality of second nozzles connected to the annular water channel and facing the inner wall of the cylinder are arranged at the bottom of the annular plate.

Preferably, the outer wall of the annular plate is provided with an annular scraper in contact with the inner wall of the cylinder.

In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

An inner jacket is set on the inner wall of the cylinder to effectively prevent the cylinder wall thickness from being too thick and affecting the heat transfer efficiency of polyethylene. In addition, circulating cooling water is introduced into the finger-shaped internal cooling pipe for auxiliary cooling, so that the heat in the production process can be transported out of the reactor in time, which can effectively ensure that the reaction proceeds normally at the appropriate temperature, thereby producing ultra-high molecular weight polyethylene.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic cross-sectional view of a structure according to an embodiment of the present invention;

FIG2 is a schematic diagram of the structure of an inner jacket provided in an embodiment of the present invention;

FIG. 3 is a schematic diagram of the structure of a finger-shaped internal cooling baffle provided in an embodiment of the present invention.

Description of the drawings: 1- cylinder; 2- stirring transmission device; 201- frame; 202- motor; 203- reducer; 204- coupling I; 205- sealing shaft; 206- mechanical seal; 207- coupling II; 3- support; 4- head; 5- half-pipe jacket; 6- inner jacket; 7- water inlet pipe; 8- water outlet pipe; 9- finger-shaped inner cooling pipe; 901- outer pipe; 902- inner pipe; 903- Finger-shaped rod; 10-feeding pipe; 11-quick opening manhole; 12-agitation shaft; 13-flushing pipe; 14-overflow discharge pipe; 15-plate and frame agitator; 16-catalyst feeding pipe; 17-temperature measuring tube; 18-discharge port; 19-multi-stage telescopic rod; 20-annular plate; 21-water inlet joint; 22-first nozzle; 23-annular water channel; 24-second nozzle; 25-annular scraper; 26-guide plate.

DETAILED DESCRIPTION

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

The present invention is described in detail below in conjunction with FIG. 1 to FIG. 3 .

Example

An ultra-ultra-high molecular weight polyethylene reactor, as shown in FIG1 , comprises a cylinder 1, upper and lower ends of the cylinder 1 are provided with end caps 4, the inner wall of the cylinder 1 is provided with an inner jacket 6, the inner jacket 6 is connected with a water inlet pipe 7 and a water outlet pipe 8 penetrating the side wall of the cylinder 1, a finger-shaped inner cooling baffle 9 is vertically arranged in the cylinder 1, as shown in FIG3 , the finger-shaped inner cooling baffle 9 comprises an outer tube 901 and a finger-shaped rod 903 arranged on the outer wall of the outer tube 901, an inner tube 902 is arranged on the inner side of the outer tube 901 and the bottom of the inner tube 902 is communicated with the outer tube 901; the inner jacket 6 has a smooth transition with the upper and lower end caps 4 without changing the stirring flow field. There are multiple groups of water inlet pipes 7 and water outlet pipes 8, which can reduce the temperature difference between the inlet and outlet water and enhance the heat exchange capacity of the inner jacket 6; as shown in Figure 2, a guide plate 26 is provided in the inner jacket 6, and the guide plate 26 is spiral, which facilitates the cooling water to flow evenly in the inner jacket 6. The guide plate 26 can also support the inner jacket 6 and increase the structural strength of the inner jacket 6.

The plate thickness of the inner jacket 6 is much smaller than that of the cylinder 1, so the inner jacket 6 is arranged on the inner wall of the cylinder 1, which can improve the efficiency of heat conduction to the inner jacket 6, and the cooling water in the inner jacket 6 can take away the heat in the reactor more quickly. The pipe opening at the upper end of the inner tube 902 is the water inlet, and the outer tube 901 is a pipe of the sealing plate. An outlet is opened on the upper side wall as a water outlet, so that cooling water is introduced for circulating cooling. The finger-shaped rod 903 can transfer heat to the outer tube 901, thereby increasing the cooling efficiency of the finger-shaped inner cooling baffle 9; the inner jacket 6 cooperates with the finger-shaped inner cooling baffle 9 to increase the heat transfer coefficient of the reactor from 700kcal/ ^hm2 .℃ of the traditional reactor to 1100kcal/ ^hm2 .℃, greatly improving the heat exchange capacity of the reactor and being able to control the reaction temperature more accurately.

A support 3 for supporting the entire reactor is provided on the outer wall of the cylinder 1; a feed pipe 10 is provided on the head 4 located above the cylinder 1, and the feed pipe 10 continuously adds materials into the reactor during production; a discharge port 18 is provided on the head 4 located below the cylinder 1, and the discharge port 18 is closed during production. After the production is stopped, the material in the reactor is discharged through the discharge port 18.

The outer walls of the two heads 4 are both provided with half-tube jackets 5. The half-tube jackets 5 are also provided with a water inlet and a water outlet. Cooling water is introduced into the half-tube jackets 5 to circulate and absorb the heat at the heads 4, further enhancing the heat exchange capacity of the reactor.

The cylinder 1 is provided with an overflow discharge pipe 14 inclined downward and a catalyst feed pipe 16 inclined upward. The overflow discharge pipe 14 can continuously discharge the reacted materials during the production process. Since the reactor of the present application is for continuous reaction, the overflow discharge pipe 14 will also be connected to another reactor (not shown in the figure), so as to avoid the material output from the feed pipe 10 flowing out of the overflow discharge pipe 14 before being completely reacted. The material discharged from the overflow discharge pipe 14 is reacted again in another reactor to ensure the quality of the product. The catalyst feed pipe 16 adds the catalyst required for the reaction to the reactor.

The overflow discharge pipe 14 and the catalyst feed pipe 16 are both provided with a flushing pipe 13. The flushing pipe 13 uses hexane as a flushing medium, which evaporates and takes away heat while flushing, thereby preventing the overflow discharge pipe 14 and the catalyst feed pipe 16 from being blocked due to ethylene polymerization.

A temperature measuring tube 17 is provided on the end cap 4 below the cylinder 1. The temperature measuring tube 17 is provided with a temperature measuring sensor, which can monitor the temperature inside the reactor and adjust the flow of cooling water at various locations according to the temperature, thereby controlling the amount of heat transfer.

The cylinder 1 is provided with a plate-frame agitator 15, the plate-frame agitator 15 is connected to a vertically arranged agitator shaft 12, the agitator shaft 12 is connected to a stirring transmission device 2 and the stirring transmission device 2 is installed on the head 4 above the cylinder 1. The plate-frame agitator 15 improves the stirring intensity shear force and the number of up and down cycles, avoids the sedimentation of the material, and the uneven stirring, and further improves the stirring and mixing effect and the heat transfer efficiency. In addition, the finger-shaped rod 903 can also cooperate with the plate-frame agitator 15 to perform auxiliary stirring operations, so that the material can be fully mixed radially and axially in the reactor, meet the requirements of polymerization kinetics, expand the reaction material in the reactor as much as possible, form a large area of film, increase the evaporation surface area, and the evaporation surface area can be continuously updated, so that the distribution range of the molecular weight is as narrow as possible to achieve a predetermined degree of polymerization.

The stirring transmission device 2 includes a frame 201 installed on the head 4, a motor 202 is installed on the frame 201, the motor 202 is connected to a reducer 203, the reducer 203 is connected to a sealing shaft 205 that movably passes through the head 4 through a coupling I 204, and a mechanical seal 206 is provided on the sealing shaft 205 for sealing the gap between the head 4 and the sealing shaft 205. The lower end of the sealing shaft 205 is connected to the stirring shaft 12 through a coupling II 207.

Both the sealing heads 4 are provided with quick opening manholes 11. During production, the quick opening manholes 11 are closed. After stopping production, the reactor can be entered through the quick opening manholes 11 to perform maintenance and cleaning operations on the equipment.

The end cap 4 located above the cylinder 1 is connected with a vertically arranged multi-stage telescopic rod 19, and the telescopic end of the multi-stage telescopic rod 19 is connected with an annular plate 20, in which an annular water channel 23 is arranged, and an inlet joint 21 connected with the annular water channel 23 is connected to the annular plate 20, and the inner wall of the annular plate 20 is provided with a plurality of first nozzles 22 connected with the annular water channel 23, and the bottom of the annular plate 20 is provided with a plurality of second nozzles 24 connected with the annular water channel 23 and facing the inner wall of the cylinder 1. The multi-stage telescopic rod 19 can be extended and retracted by screw transmission; as shown in FIG1 , during production, the multi-stage telescopic rod 19 remains in a contracted state, and the annular plate 20 is located above the overflow discharge pipe 14; after stopping production, when the inside of the reactor needs to be cleaned, the quick opening manhole 11 above is opened, and a high-pressure water pipe is extended from the quick opening manhole 11 to connect to the inlet joint 21, and the power line is connected to the multi-stage telescopic rod 19. The multi-stage telescopic rod 19 is controlled to extend to drive the annular plate 20 to descend, so that the first nozzle 22 flushes the plate-frame agitator 15 and the finger-shaped internal cooling baffle 9, and the second nozzle 24 flushes the inner wall of the cylinder 1. Part of the first nozzle 22 is aimed at the plate-frame agitator 15, and the other part of the first nozzle 22 sprays water along the circumference of the finger-shaped internal cooling baffle 9. The plate-frame agitator 15 needs to be rotated during cleaning to achieve circumferential all-round flushing. By setting the multi-stage telescopic rod 19, the first nozzle 22 and the second nozzle 24 to flush the internal structure of the reactor, the labor intensity of manual cleaning is reduced.

The outer wall of the annular plate 20 is provided with an annular scraper 25 in contact with the inner wall of the cylinder 1. The annular scraper 25 can scrape off the material that has not been washed off the inner wall of the cylinder 1 and can also scrape off some water stains so as to dry the reactor later.

The present application effectively improves the production capacity, heat transfer capacity and stirring effect of the reactor, makes the gas-liquid phase evenly distributed, the reaction pressure is low, the material concentration is low, avoids the danger of explosion and agglomeration, and at the same time, keeps the catalyst in a moving state and does not agglomerate; ensures that the gas, liquid and solid phases are fully mixed and contacted in the reactor, evenly distributed and maintains a certain residence time for the continuous phase and the dispersed phase, improves the production intensity and product quality, and provides an ideal device for the production of ultra-high molecular polyethylene.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (8)

1. An ultra-ultra-high molecular weight polyethylene reactor, comprising a cylinder (1), wherein both upper and lower ends of the cylinder (1) are provided with a head (4), characterized in that an inner jacket (6) is provided on the inner wall of the cylinder (1), the inner jacket (6) is connected with a water inlet pipe (7) and a water outlet pipe (8) penetrating the side wall of the cylinder (1), a finger-shaped inner cooling baffle (9) is vertically arranged in the cylinder (1), the finger-shaped inner cooling baffle (9) comprises an outer tube (901) and a finger-shaped rod (903) arranged on the outer wall of the outer tube (901), an inner tube (902) is arranged on the inner side of the outer tube (901), and the bottom of the inner tube (902) is communicated with the outer tube (901), a plurality of groups of water inlet pipes (7) and water outlet pipes (8) are provided, and a guide plate (26) is provided in the inner jacket (6). 2. An ultra-ultra-high molecular weight polyethylene reactor according to claim 1, characterized in that a half-tube jacket (5) is provided on the outer wall of the two heads (4). 3. An ultra-ultra-high molecular weight polyethylene reactor according to claim 1, characterized in that a downwardly inclined overflow discharge pipe (14) and an upwardly inclined catalyst feed pipe (16) are provided on the cylinder (1). 4. An ultra-ultra-high molecular weight polyethylene reactor according to claim 3, characterized in that a flushing pipe (13) is provided on both the overflow discharge pipe (14) and the catalyst feed pipe (16). 5. An ultra-ultra-high molecular weight polyethylene reactor according to claim 1, characterized in that a plate-frame agitator (15) is arranged in the cylinder (1), the plate-frame agitator (15) is connected to a vertically arranged stirring shaft (12), the stirring shaft (12) is connected to a stirring transmission device (2), and the stirring transmission device (2) is installed on a head (4) above the cylinder (1). 6. An ultra-ultra-high molecular weight polyethylene reactor according to claim 1, characterized in that quick-opening manholes (11) are provided on both of the two heads (4). 7. An ultra-ultra-high molecular weight polyethylene reactor according to claim 6, characterized in that the head (4) located above the cylinder (1) is connected to a vertically arranged multi-stage telescopic rod (19), the telescopic end of the multi-stage telescopic rod (19) is connected to an annular plate (20), an annular water channel (23) is arranged in the annular plate (20), a water inlet joint (21) connected to the annular water channel (23) is connected to the annular plate (20), the inner wall of the annular plate (20) is provided with a plurality of first nozzles (22) connected to the annular water channel (23), and the bottom of the annular plate (20) is provided with a plurality of second nozzles (24) connected to the annular water channel (23) and facing the inner wall of the cylinder (1). 8. An ultra-ultra-high molecular weight polyethylene reactor according to claim 7, characterized in that the outer wall of the annular plate (20) is provided with an annular scraper (25) in contact with the inner wall of the cylinder (1).