Tower type continuous isocyanate reactor

Abstract

The utility model provides an isocyanate tower type continuous reactor which comprises a reaction cavity, and the reaction cavity comprises a first reaction part and a second reaction part which are sequentially arranged from top to bottom; the first reaction part and the second reaction part respectively and independently comprise at least two crossed tower plates, the tower plates are fixedly connected to the inner wall of the tower type continuous reactor, and a baffling assembly is arranged at one end of each tower plate; the tower-type continuous reactor comprises a stirring assembly, the stirring assembly comprises stirring sub-assemblies with the same number as the tower plates, and the stirring sub-assemblies are arranged above the tower plates; a liquid phase feeding hole is formed above the first reaction part, and a gas phase feeding hole is formed below the second reaction part. The tower type continuous reactor can continuously produce reaction liquid with higher concentration, the number of equipment is small, the phosgene and solvent consumption is low, and the industrial production cost is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of synthesis equipment and relates to an isocyanate tower-type continuous reactor. Background Technology

[0002] Polyurethane materials prepared from aliphatic diisocyanate (ADI) series products have excellent mechanical properties, outstanding chemical stability, and excellent weather resistance. They are widely used in high-grade building exterior wall coatings, automotive coatings, product shell coatings, industrial equipment pipelines, thermal insulation materials, foam plastics, synthetic fibers, coatings, and solid elastomers; as well as light industrial products closely related to daily life, such as clothing and footwear, synthetic leather, and high-end waterproof materials.

[0003] Industrially, aliphatic diisocyanates are mostly prepared by reacting aliphatic diamines with phosgene, including gas-phase and liquid-phase methods. The gas-phase phosgene method has advantages such as high yield and large production volume, but it also has drawbacks such as susceptibility to equipment and pipeline blockage, stringent requirements for equipment materials, high investment costs, and high technological barriers. Liquid-phase methods include batch reactors and series batch reactors. Patent CN115155467B discloses a system for synthesizing hexamethylene diisocyanate using liquid-phase phosgenation, including a bubble column pre-synthesis reactor, a bubble column ripening reactor, a heat exchanger, a condenser, and a flash evaporation vessel, with each component connected accordingly. Compared with the traditional batch liquid-phase phosgene method, it can significantly improve mass and heat transfer, accelerate reaction efficiency, increase reaction conversion rate, and improve the purity of the reaction solution.

[0004] However, existing liquid-phase phosgenation technology still has the following problems: 1) It requires a large number of devices, occupies a large system space, has a high overall investment, and a long investment recovery period; 2) The gas and liquid phases are freely distributed in the pre-synthesis reactor, which cannot guarantee uniform mixing of materials; the material discharged from the top of the pre-synthesis reactor into the maturation reactor will cause serious axial backmixing; 3) Both phosgene and aliphatic amine are fed from the bottom. When the two materials come into contact at the bottom, they will react to generate carbamoyl chloride solid, which may block the feed port and cause overpressure; 4) Both reactors need to be purged with phosgene, but most of the phosgene in the maturation reactor is used to maintain the phosgene atmosphere, and the condenser cannot completely condense all the phosgene, which will cause a large amount of phosgene to escape, putting a great burden on the phosgene recovery and tail gas treatment systems; 5) The amine feed side is a mixed solution of aliphatic amine and solvent, with an amine mass concentration of only 5%~15%. For this type of continuous reaction, a large amount of solvent will enter the downstream or tail gas treatment system with the reaction liquid, increasing the solvent consumption. Utility Model Content

[0005] To address the technical problems existing in the prior art, this utility model provides an isocyanate tower continuous reactor, which can continuously produce reaction solutions with higher concentrations, requires fewer pieces of equipment, and consumes less phosgene and solvents, thereby reducing industrial production costs.

[0006] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0007] This utility model provides an isocyanate tower-type continuous reactor, which includes a reaction chamber, and the reaction chamber includes a first reaction section and a second reaction section arranged sequentially from top to bottom;

[0008] The first reaction section and the second reaction section each independently include at least two cross-arranged trays, which are fixedly connected to the inner wall of the tower-type continuous reactor, and a baffle assembly is provided at one end of the tray;

[0009] The tower-type continuous reactor includes a stirring assembly, which includes stirring sub-assemblies equal in number to the tower plates, and the stirring sub-assemblies are disposed above the tower plates;

[0010] A liquid phase inlet is provided above the first reaction section, and a gas phase inlet is provided below the second reaction section.

[0011] As a preferred technical solution of this utility model, the tower plate is provided with a bubble cap.

[0012] As a preferred technical solution of this utility model, the stirring assembly includes a shaft and a stirring sub-assembly disposed on the shaft, the stirring sub-assembly including stirring blades.

[0013] As a preferred technical solution of this utility model, the tower-type continuous reactor includes a heating component.

[0014] As a preferred technical solution of this utility model, the heating component includes a jacket disposed outside the reaction chamber, a heat source inlet disposed at the bottom of the jacket, and a heat source outlet disposed at the top of the jacket.

[0015] As a preferred technical solution of this utility model, the tower-type continuous reactor includes a gas-liquid separation component, which is disposed above the first reaction section.

[0016] As a preferred technical solution of this utility model, a gas phase outlet is provided at the top of the tower-type continuous reactor.

[0017] As a preferred technical solution of this utility model, a liquid phase outlet is provided at the bottom of the tower-type continuous reactor.

[0018] As a preferred technical solution of this utility model, the tower-type continuous reactor is provided with a condensate reflux port.

[0019] As a preferred technical solution of this utility model, the gas phase outlet is connected to the gas inlet of the condensing device, and the condensation reflux port is connected to the liquid outlet of the condensing device.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] (1) This utility model provides an isocyanate tower continuous reactor, which can produce continuously, with a short residence time of the reaction liquid and high time efficiency. The two-step reaction is carried out in the same reactor, which can realize the gradient distribution of product concentration in the reactor and enrich it at the bottom of the tower to obtain a reaction liquid with a higher concentration.

[0022] (2) This utility model provides an isocyanate tower continuous reactor, which has a small number of equipment and high space utilization;

[0023] (3) This utility model provides an isocyanate tower continuous reactor, which has high reaction conversion rate and efficiency with low phosgene consumption; the reaction is a two-stage reaction: the first reaction section is for the formation of carbamoyl chloride, and the second reaction section is for the decomposition of carbamoyl chloride into isocyanate. Phosgene does not participate in the reaction but requires a light atmosphere. Phosgene is introduced from the bottom of the reactor, which can provide a sufficient light atmosphere environment in the second stage of the reaction, reducing the generation of by-products, while the first stage of the reaction can make full use of the rising phosgene in the reactor to maximize phosgene utilization;

[0024] (4) This utility model provides an isocyanate tower continuous reactor. The reactor has low solvent consumption, high amine salt feed concentration, and amine salt mass content can reach 30%~40%. For this type of continuous reaction, the unit amount of solvent entering the reactor is small, so the solvent content of the reactor output is low, and therefore the solvent loss is less.

[0025] (5) This utility model provides an isocyanate tower continuous reactor. The reactor operates under low pressure and high temperature conditions, which allows the solvent to be repeatedly vaporized and liquefied in the reactor, increasing the gas flow rate in the tower. At the same time, with the addition of the stirring components, the materials can be mixed more thoroughly without axial back-mixing. Attached Figure Description

[0026] Figure 1 This is a schematic diagram showing the connection between the isocyanate tower continuous reactor and other devices provided in Embodiment 1 of this utility model;

[0027] Figure 2 This is a schematic diagram of the isocyanate tower continuous reactor provided in Embodiment 1 of this utility model;

[0028] Figure 3 This is a schematic diagram of the material flow direction in the isocyanate tower continuous reactor provided in Embodiment 1 of this utility model;

[0029] In the diagram: 1-Tower continuous reactor, 2-Preheater, 3-Waste gas collection pipeline, 4-Condenser, 5-Downstream distillation system, 1-1-Stirring shaft, 1-2-Gas phase outlet, 1-3-Reaction chamber, 1-4-Cyclone separator, 1-5-Flange, 1-6-Gas phase inlet, 1-7-Stirring blade, 1-8-Baffle plate, 1-9-Jacket, 1-10-Heat source inlet, 1-11-Gas phase inlet, 1-12-Liquid phase outlet, 1-13-Heat source outlet, 1-14-Condensation reflux port.

[0030] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be determined by the claims. Detailed Implementation

[0031] The technical solution of this application will be further described below through specific implementation methods.

[0032] This utility model provides an isocyanate tower-type continuous reactor, which includes a reaction chamber, and the reaction chamber includes a first reaction section and a second reaction section arranged sequentially from top to bottom;

[0033] The first reaction section and the second reaction section each independently include at least two cross-arranged trays, which are fixedly connected to the inner wall of the tower-type continuous reactor, and a baffle assembly is provided at one end of the tray;

[0034] The tower-type continuous reactor includes a stirring assembly, which includes stirring sub-assemblies equal in number to the tower plates, and the stirring sub-assemblies are disposed above the tower plates;

[0035] A liquid phase inlet is provided above the first reaction section, and a gas phase inlet is provided below the second reaction section.

[0036] In one specific embodiment of this utility model, the first reaction section and the second reaction section are not two independent reaction regions in the reaction chamber. Since the reaction between aliphatic amines and phosgene can be divided into two stages, the first reaction stage is the process of aliphatic amines reacting with phosgene to generate the corresponding aliphatic carbamoyl chloride, and the second reaction stage is the process of the aliphatic carbamoyl chloride decomposing to generate isocyanate. The first reaction stage takes place in the upper part of the reaction chamber, hence it is called the first reaction section, and the second reaction stage takes place in the lower part of the reaction chamber, hence it is called the second reaction section.

[0037] In one specific embodiment of this utility model, the cross arrangement can be understood as follows: the first tray at the top of the reaction chamber is fixedly arranged on one side of the inner wall, the second tray below is fixedly arranged on the opposite side of the inner wall of the first tray, the third tray is fixedly arranged on the inner wall of the same side as the first tray, and so on.

[0038] In one specific embodiment of this invention, the number of trays can be adjusted according to the reaction scale and actual reaction effect, and is not specifically limited here. For example, the first reaction section has 3 trays, and the second reaction section has 4 trays.

[0039] In one specific embodiment of this utility model, the liquid phase feed inlet is located above the first tray at the top of the first reaction section, and the gas phase feed inlet is located below the last tray at the bottom of the second reaction section.

[0040] In one specific embodiment of this utility model, the tray is provided with bubble caps for gas phase passage. The number of bubble caps provided on each tray can be adjusted according to reaction conditions such as gas phase flow rate, and is not specifically limited here.

[0041] In one specific embodiment of this utility model, the stirring assembly includes a shaft with a plurality of stirring blades. The number of stirring blades is set according to the number of trays, ensuring that each tray has an independent stirring blade to stir the liquid phase above the tray.

[0042] In one specific embodiment of this utility model, the tower-type continuous reactor includes a heating assembly. The main body of the heating assembly is a jacket, which surrounds the sidewall of the reaction chamber. A heat source inlet is provided at the bottom of the jacket, and a heat source outlet is provided at the top of the jacket. The heat source heats the reaction chamber to achieve the required reaction temperature. The heat source can be selected according to heating needs and cost, etc., and is not specifically limited here.

[0043] In one specific embodiment of this invention, the tower-type continuous reactor includes a gas-liquid separation component, which is disposed above the first reaction section. For example, the gas-liquid separation component may be a cyclone separator.

[0044] In one specific embodiment of this invention, a gas phase outlet is provided at the top of the tower-type continuous reactor. Specifically, it is located above the gas-liquid separation component.

[0045] In one specific embodiment of this utility model, a liquid phase outlet is provided at the bottom of the tower-type continuous reactor.

[0046] In one specific embodiment of this utility model, the tower-type continuous reactor is provided with a condensation reflux port, the gas phase outlet is connected to the gas inlet of the condensation device, and the condensation reflux port is connected to the liquid outlet of the condensation device.

[0047] In one specific embodiment of this utility model, the condensation device is provided with a non-condensable gas outlet, which is connected to the waste gas recovery pipeline.

[0048] In one specific embodiment of this utility model, a preheating device is installed on the gas phase pipeline connected to the gas phase inlet to preheat the gas phase.

[0049] In one specific embodiment of this utility model, the liquid phase outlet is connected to a downstream distillation system for further purification of the product.

[0050] The operation mode of the isocyanate tower continuous reactor provided in the specific embodiments of this utility model includes:

[0051] Liquid feedstock enters the reactor through the liquid inlet, spreading evenly across the trays. Preheated gaseous feedstock enters the reactor through the gas inlet, overflowing through bubble caps on the trays and reacting with the liquid feedstock. A stirring assembly positioned above the trays mixes the liquid and gaseous feedstocks. When the liquid level on a tray exceeds the height of the baffle plate, the liquid flows to the next tray to continue the reaction. In the first reaction section, aliphatic amines react with phosgene to produce aliphatic carbamoyl chloride. In the second reaction section, aliphatic carbamoyl chloride decomposes to produce aliphatic isocyanates. A heat source enters the jacket through the heat source inlet to heat the reactor, and the heat source exits the jacket through the heat source outlet. The reacted liquid phase enters the downstream distillation system for purification through the liquid phase outlet. The gaseous phase passes through a gas-liquid separator and then enters the condenser through the gas phase outlet. Non-condensable gases are collected through a waste gas collection pipeline, and the condensed liquid is returned to the reactor through the condenser reflux port to continue the reaction.

[0052] To better illustrate this utility model and facilitate understanding of its technical solution, typical but non-limiting embodiments of this utility model are as follows:

[0053] Example

[0054] This embodiment provides an isocyanate tower-type continuous reactor, the structure of which is as follows: Figure 1-3 As shown, the tower-type continuous reactor 1 includes reaction chambers 1-3, and the reaction chambers include a first reaction section and a second reaction section arranged sequentially from top to bottom;

[0055] The first reaction section is equipped with three cross-arranged trays, and the second reaction section is equipped with four cross-arranged trays. The trays are fixedly connected to the inner wall of the tower-type continuous reactor, and baffles 1-8 are provided at one end of the trays.

[0056] The tower-type continuous reactor 1 includes a stirring assembly, which includes a stirring shaft 1-1. The stirring shaft 1-1 is provided with stirring blades 1-7, which are equal in number to the number of tower plates. The stirring blades 1-7 are arranged above each tower plate.

[0057] The tower-type continuous reactor 1 includes a heating assembly, the main body of which is a jacket 1-9. The jacket 1-9 encloses the sidewall of the reaction chamber 1-3. A heat source inlet 1-10 is provided at the bottom of the jacket 1-9, and a heat source outlet 1-13 is provided at the top of the jacket 1-9. The tower-type continuous reactor 1 also includes a gas-liquid separation assembly, which is a cyclone separator 1-4.

[0058] A liquid inlet 1-6 is provided above the first reaction section, and a gas inlet 1-11 is provided below the second reaction section. A preheater 2 is provided on the pipeline connected to the gas inlet 1-11. A gas outlet 1-2 is provided at the top of the tower-type continuous reactor 1, which is located above the cyclone separator 1-4. The tower-type continuous reactor 1 is also provided with a condensate reflux port 1-14. The gas outlet 1-2 is connected to the gas inlet of the condenser 4, and the condensate reflux port 1-14 is connected to the liquid outlet of the condenser 4. The non-condensable gas outlet of the condenser 4 is connected to the waste gas collection pipeline 3. A liquid outlet 1-12 is provided at the bottom of the tower-type continuous reactor 1, and the liquid outlet 1-12 is connected to the downstream distillation system 5.

[0059] Example 2

[0060] This embodiment provides an operating method for the isocyanate tower continuous reactor provided in Example 1, the operating method including:

[0061] A 0.1MPa(G) ambient temperature phosgene stream a is preheated to 85~100℃ by preheater 2, and then a phosgene stream b enters the tower continuous reactor 1 through the gas phase feed inlet 1-11. The heat source enters the jacket 1-9 through the heat source inlet 1-10 to heat the tower continuous reactor 1, and the heat source after heat exchange flows out of the jacket 1-9 through the heat source outlet 1-13. When the phosgene feed is stable and the temperature inside the tower is maintained at about 170℃, a 0.05MPa(G) ambient temperature 1-5-pentanediamine (PDA) carbonate (mixture, average molecular weight 216) mixed with o-dichlorobenzene (ODCB) stream c enters the tower continuous reactor 1 through the liquid phase feed inlet 1-6. The molar ratio of PDA salt to ODCB is 1:3, and the molar ratio of PDA salt to phosgene is 1:3.5~4.

[0062] The mixed stream (c) is spread evenly across the trays. Phosgene overflows through the bubble caps on the trays and reacts with the liquid feed. Stirring blades 1-7, positioned above the trays, are driven by stirring shaft 1-1 to mix the liquid and gaseous feeds. When the liquid level on the tray exceeds the height of baffles 1-8, the liquid flows to the next tray to continue the reaction. The trays in the first reaction section (3 trays) undergo a reaction where PDA salt reacts with phosgene to produce 1,5-pentanedicarbamoyl chloride. The trays in the second reaction section (4 trays) undergo a reaction where 1,5-pentanedicarbamoyl chloride decomposes to produce 1,5-pentanediisocyanate (PDI).

[0063] The reaction liquid g after the reaction enters the downstream distillation system for purification through the liquid phase outlet. The reaction waste gas d is separated into gas and liquid by cyclone separator 1-4 and enters condenser 4 through gas phase outlet 1-2. The non-condensable gas e is collected by waste gas collection pipeline 3, which is connected to a micro negative pressure system of 98 kPa (A). The liquid obtained by condensation is returned to the tower continuous reactor 1 through condensation reflux port 1-14 to continue the reaction.

[0064] In this embodiment, the reaction liquid phase flows downward in the first reaction section, and phosgene is continuously introduced at a constant ratio. By the third tray, the PDA in the reaction liquid has been almost completely reacted. The reaction liquid continues to flow downward into the second reaction section. Under sufficient light atmosphere, the intermediate product carbamoyl chloride gradually decomposes. From the fourth tray to the seventh tray, carbamoyl chloride is finally completely decomposed. After sampling and testing at the liquid phase outlet, a PDI reaction liquid with a mass content of 24.3% is obtained, with a conversion rate of 100%.

[0065] The applicant declares that the detailed structural features of this utility model are illustrated through the above embodiments, but this utility model is not limited to the above detailed structural features, that is, it does not mean that this utility model must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to this utility model, equivalent substitutions of selected components, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this utility model.

[0066] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0067] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.

[0068] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.

Claims

1. A continuous isocyanate tower reactor, characterized in that, The tower-type continuous reactor includes a reaction chamber, which comprises a first reaction section and a second reaction section arranged sequentially from top to bottom; The first reaction section and the second reaction section each independently include at least two cross-arranged trays, the trays being fixedly connected to the inner wall of the tower-type continuous reactor, and a baffle assembly being provided at one end of each tray; The tower-type continuous reactor includes a stirring assembly, which includes stirring sub-assemblies equal in number to the tower plates, and the stirring sub-assemblies are disposed above the tower plates; A liquid phase inlet is provided above the first reaction section, and a gas phase inlet is provided below the second reaction section.

2. The tower-type continuous reactor according to claim 1, characterized in that, The tray is equipped with a bubble cap.

3. The tower-type continuous reactor according to claim 1, characterized in that, The stirring assembly includes a shaft and a stirring sub-assembly disposed on the shaft, the stirring sub-assembly including stirring blades.

4. The tower-type continuous reactor according to claim 1, characterized in that, The tower-type continuous reactor includes a heating assembly.

5. The tower-type continuous reactor according to claim 4, characterized in that, The heating assembly includes a jacket disposed outside the reaction chamber, with a heat source inlet at the bottom of the jacket and a heat source outlet at the top of the jacket.

6. The tower-type continuous reactor according to claim 1, characterized in that, The tower-type continuous reactor includes a gas-liquid separation component, which is disposed above the first reaction section.

7. The tower-type continuous reactor according to claim 1, characterized in that, The tower-type continuous reactor is equipped with a gas phase outlet at the top.

8. The tower-type continuous reactor according to claim 1, characterized in that, The tower-type continuous reactor is equipped with a liquid phase outlet at the bottom.

9. The tower-type continuous reactor according to claim 7, characterized in that, The tower-type continuous reactor is equipped with a condensate reflux port.

10. The tower-type continuous reactor according to claim 9, characterized in that, The gas phase outlet is connected to the gas inlet of the condenser, and the condensate return port is connected to the liquid outlet of the condenser.

Images