Device for producing industrial special isocyanate by recycling carbon dioxide

Abstract

The utility model relates to a device for producing industrial special isocyanate by recycling carbon dioxide, which is characterized in that a salt forming reactor is connected with a liquid outlet pipe of a first ejector, and the first ejector is connected with a CO2 inlet pipe and a liquid outlet pipe of a premixer; a discharge pipe at the bottom of the salifying reactor is connected with a rear mixer; a liquid outlet pipe of the rear mixer is connected with a reboiler; an outlet of the reboiler is connected with a second ejector; an outlet of the second ejector is connected with a photochemical reactor; a gas phase outlet in the upper part of the hydrochloric acid absorption tower is connected with a first ejector through a CO2 recovery pipe; a bottom discharging pipe of the photochemical reactor is connected with a first heat exchanger; an outlet of the first heat exchanger is connected into a second ejector. The waste CO2 gas is used as the protective gas, so that the amine raw material firstly reacts with the CO2 gas to generate amino carbonate, then the amino carbonate and phosgene are subjected to photochemical reaction, and more byproducts caused by too high heating rate are avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical equipment, and particularly relates to a device for recycling carbon dioxide to produce industrial special isocyanates. Background Art

[0002] Isocyanates are the general names of various esters of isocyanic acid. According to the number of groups, isocyanates can be divided into monoisocyanates, diisocyanates, and polyisocyanates, etc. Among them, diisocyanates include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), and pentamethylene diisocyanate (PDI), etc. The isocyanate structure contains unsaturated bonds and has high activity, and it is the key raw material for producing polyurethanes. With the continuous improvement of China's scientific and technological level, the production capacity of isocyanates such as TDI and MDI ranks first in the world. However, despite this, the types of isocyanates with independent intellectual property rights in China are still few, and products such as PDI and XDI using amino compounds as raw materials are still in the research and development stage. Compared with developed countries such as Japan, the United States, and Germany, there are still certain gaps in the technology, types, and performance of China's isocyanate industry. At the same time, in the process of industrial production, the controllable utilization of carbon dioxide (CO2) is an important environmental protection issue. With the increasing global attention to climate change, reducing greenhouse gas emissions has become the common responsibility of governments and enterprises. The carbon dioxide emitted by industries can be captured, stored, and utilized through a series of technical means (CCU: Carbon Capture and Utilization), thereby reducing its impact on the atmosphere. Therefore, while developing special isocyanates, the efficient utilization of CO2 waste gas generated in chemical production is the key to green chemical production. Summary of the Invention

[0003] The purpose of the utility model is to overcome the problems existing in the prior art and provide a device for recycling carbon dioxide to produce industrial special isocyanates.

[0004] To achieve the above object, the utility model adopts the following technical solutions: A device for recycling carbon dioxide to produce industrial special isocyanate, including a salt-forming reactor, a photochemical reactor, and a gas-liquid separation tank, characterized in that: the liquid outlet pipe of the first ejector is connected to the salt-forming reactor, and the CO2 inlet pipe and the liquid outlet pipe of the pre-mixer are connected to the first ejector; the discharge pipe at the bottom of the salt-forming reactor is connected to the post-mixer through a peristaltic pump, the liquid outlet pipe of the post-mixer is connected to a reboiler, the outlet of the reboiler is connected to a second ejector, the outlet of the second ejector is connected to the photochemical reactor, the gas phase pipe at the upper part of the photochemical reactor is connected to the gas-liquid separation tank, the gas phase outlet at the top of the gas-liquid separation tank is connected to a hydrochloric acid absorption tower, and the upper gas phase outlet of the hydrochloric acid absorption tower is connected to the first ejector through a CO2 recovery pipe; the discharge pipe at the bottom of the photochemical reactor is connected to a first heat exchanger through a circulation pump, and the outlet of the first heat exchanger is connected to the second ejector.

[0005] The amine raw material feed pipe is connected to the pre-mixer, and a third control valve is provided on the amine raw material feed pipe; the liquid outlet pipe of the second heat exchanger is connected to the pre-mixer, a second control valve is provided on this liquid outlet pipe, and the inlet of the second heat exchanger is connected to the solvent inlet pipe; the second control valve and the third control valve are controlled by DCS.

[0006] The upper part of the salt-forming reactor is connected to a gas discharge pipe, the gas discharge pipe is connected to the CO2 inlet pipe, a first control valve is provided on the CO2 inlet pipe, a fourth control valve for controlling the pressure of the salt-forming reactor is provided on the gas discharge pipe, and a fifth control valve for discharging materials is provided on the discharge pipe at the bottom of the salt-forming reactor; the first control valve, the fourth control valve and the fifth control valve are controlled by DCS.

[0007] A flushing pump is also connected to the post-mixer.

[0008] A phosgene inlet pipe is connected to the second ejector, a sixth control valve for controlling the phosgene flow rate is provided on the phosgene inlet pipe, and the sixth control valve is controlled by DCS.

[0009] A seventh control valve for controlling its pressure is provided on the gas phase pipe at the upper part of the photochemical reactor, and an eighth control valve for discharging materials is provided on the discharge pipe at the bottom of the photochemical reactor. The seventh control valve and the eighth control valve are controlled by DCS.

[0010] A product collection pipe is also connected to the discharge pipe at the bottom of the photochemical reactor, a ninth control valve for controlling the product flow rate is provided on the product collection pipe, and the ninth control valve is controlled by DCS.

[0011] A tenth control valve is provided on the gas-phase pipe at the top of the gas-liquid separation tank, and an eleventh control valve for controlling the outlet flow rate is provided on the liquid-phase pipe at the bottom; a water inlet pipe is connected to the upper part of the hydrochloric acid absorption tower, and a twelfth control valve is provided on the water inlet pipe; a thirteenth control valve for controlling the hydrochloric acid flow rate is provided on the hydrochloric acid discharge pipe at the bottom of the hydrochloric acid absorption tower; the tenth control valve, the eleventh control valve, the twelfth control valve, and the thirteenth control valve are controlled by DCS.

[0012] A fourteenth control valve is provided on the CO2 recovery pipe, and the fourteenth control valve is controlled by DCS.

[0013] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0014] 1. By adopting a dual injection device, the injection reaction is a gas-liquid contact reaction. During the reaction process, the contact area is large and the reaction time is short, ensuring the improvement of the production rate and thus reducing the production cost;

[0015] 2. Using the waste CO2 gas as a protective gas, the amine raw material first reacts with the CO2 gas to form an amino carbonate, and then undergoes a photochemical reaction with phosgene, avoiding the generation of more by-products due to too fast heating rate and the pyrolysis of the amine raw material to produce crude coal tar, coke, ammonia, and other unexpected compounds, and avoiding the attachment of crude coal tar and coke on the surface of the injector, resulting in a decrease in vaporization efficiency and increasing the difficulty of cleaning the injector.

[0016] 3. The hydrogen chloride gas generated by the photochemical reaction will be carried out by the CO2 gas generated by the photochemical reaction of the amino carbonate, avoiding the generation of impurities and by-products caused by the presence of hydrogen chloride gas in the reaction system. At the same time, after being treated by the hydrochloric acid absorption tower, the generated hydrochloric acid has commercial value and can be sold as a by-product.

[0017] 4. The present utility model is widely applied to special isocyanates with amines as raw materials, and can effectively utilize the waste CO2, meeting the requirements of green chemical production processes and having general applicability. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the present utility model.

[0019] In the figure: 1 - pre - mixer, 2 - first ejector, 3 - salification reactor, 4 - peristaltic pump, 5 - post - mixer, 6 - flushing pump, 7 - reboiler, 8 - second ejector, 9 - photoreactor, 10 - circulation pump, 11 - first heat exchanger, 12 - gas - liquid separation tank, 13 - hydrochloric acid absorption tower, 14 - second heat exchanger; L1 - CO2 inlet pipe, L2 - gas discharge pipe, L3 - product collection pipe, L4 - CO2 recovery pipe; F1 - first control valve, F2 - second control valve, F3 - third control valve; F4 - third control valve, F5 - salification reactor discharge valve, F6 - sixth control valve, F7 - seventh control valve, F8 - eighth control valve, F9 - ninth control valve, F10 - tenth control valve, F11 - eleventh control valve, F12 - twelfth control valve, F13 - thirteenth control valve, F14 - fourteenth control valve. Detailed implementation manners

[0020] The technical solutions of the present utility model will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of this patent, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this patent without creative efforts shall fall within the protection scope of this patent.

[0021] Embodiment 1

[0022] See Figure 1 , a device for recycling carbon dioxide to produce industrial special isocyanates, characterized in that: the liquid outlet pipe of the first ejector 2 is connected to the salification reactor 3, and the CO2 inlet pipe L1 and the liquid outlet pipe of the pre - mixer 1 are connected to the first ejector 2; the discharge pipe at the bottom of the salification reactor 3 is connected to the post - mixer 5 through the peristaltic pump 4, the liquid outlet pipe of the post - mixer 5 is connected to the reboiler 7, the outlet of the reboiler 7 is connected to the second ejector 8, the outlet of the second ejector 8 is connected to the photoreactor 9, the upper gas phase pipe of the photoreactor 9 is connected to the gas - liquid separation tank 12, the top gas phase port of the gas - liquid separation tank 12 is connected to the hydrochloric acid absorption tower 13, and the upper gas phase outlet of the hydrochloric acid absorption tower 13 is connected to the first ejector 2 through the CO2 recovery pipe L4; the discharge pipe at the bottom of the photoreactor 9 is connected to the first heat exchanger 11 through the circulation pump 10, and the outlet of the first heat exchanger 11 is connected to the second ejector 8.

[0023] The amine raw material feed pipe is connected to the pre - mixer 1, and the third control valve F3 is provided on the amine raw material feed pipe; the liquid outlet pipe of the second heat exchanger 14 is connected to the pre - mixer 1, the second control valve F2 is provided on this liquid outlet pipe, and the inlet of the second heat exchanger 14 is connected to the solvent inlet pipe; the second control valve F2 and the third control valve F3 are controlled by DCS.

[0024] The upper part of the salt-forming reactor 3 is connected to a gas discharge pipe L2, and the gas discharge pipe L2 is connected to a CO2 inlet pipe L1. A first control valve F1 is provided on the CO2 inlet pipe L1, and a fourth control valve F4 for controlling the pressure of the salt-forming reactor 3 is provided on the gas discharge pipe L2. A fifth control valve F5 for discharging materials is provided on the discharging pipe at the bottom of the salt-forming reactor 3; the first control valve F1, the fourth control valve F4, and the fifth control valve F5 are controlled by DCS.

[0025] A flushing pump 6 is also connected to the post-mixer 5.

[0026] A phosgene inlet pipe is connected to the second ejector 8, and a sixth control valve F6 for controlling the phosgene flow rate is provided on the phosgene inlet pipe. The sixth control valve F6 is controlled by DCS.

[0027] A seventh control valve F7 for controlling its pressure is provided on the gas phase pipe at the upper part of the photochemical reactor 9, and an eighth control valve F8 for discharging materials is provided on the discharging pipe at the bottom. The seventh control valve F7 and the eighth control valve F8 are controlled by DCS.

[0028] A product collection pipe L3 is also connected to the discharging pipe at the bottom of the photochemical reactor 9, and a ninth control valve F9 for controlling the product flow rate is provided on the product collection pipe L3. The ninth control valve F9 is controlled by DCS.

[0029] A tenth control valve F10 is provided on the gas phase pipe at the top of the gas-liquid separation tank 12, and an eleventh control valve F11 for controlling the outlet flow rate is provided on the liquid phase pipe at the bottom; a water inlet pipe is connected to the upper part of the hydrochloric acid absorption tower 13, and a twelfth control valve F12 is provided on the water inlet pipe; a thirteenth control valve F13 for controlling the hydrochloric acid flow rate is provided on the hydrochloric acid discharge pipe at the bottom of the hydrochloric acid absorption tower 13; the tenth control valve F10, the eleventh control valve F11, the twelfth control valve F12, and the thirteenth control valve F13 are controlled by DCS.

[0030] A fourteenth control valve F14 is provided on the CO2 recovery pipe L4, and the fourteenth control valve F14 is controlled by DCS.

[0031] The working process of the present invention will be explained below by taking the production of hexamethylene diisocyanate by the photochemical method as an example:

[0032] First, the salt-forming reactor 3 is filled with a solvent as a primer, and the solvent liquid level is controlled at 20 - 50%.

[0033] The solvent enters the pre-mixer 1 under the control of the second control valve F2 through the second heat exchanger 14 to form a mixed solvent. The amine raw material enters the pre-mixer 1 under the control of the third control valve F3. After mixing, it enters the first ejector 2. At the same time, the CO2 inlet flow rate is controlled by the first control valve F1, and the recycled CO2 gas flow rate is controlled by the fourteenth control valve F14, so that the mixed solvent and the CO2 solvent are in full contact through gas-liquid reaction during the injection process to form amino carbonate.

[0034] After the injection reaction is completed, the material enters the salt-forming reactor 3 and is fully stirred. During the stirring process, the pressure of the salt-forming reactor 3 is controlled by the fourth control valve F4, and the excess CO2 gas is discharged through the gas discharge pipe L2 to continue the process cycle.

[0035] The fifth control valve F5 is controlled to discharge the material, and the material is transported to the post-mixer 5 through the peristaltic pump 4. After the transportation is completed, the solvent pump 6 is started to flush the pipeline.

[0036] After the amino carbonate is fully mixed in the post-mixer 5, the amino carbonate is heated by the reboiler 7. After the temperature reaches the process production requirement, it is introduced into the second ejector 8. At the same time, the phosgene flow rate is controlled by the fourth control valve F6, so that the amino carbonate and phosgene carry out a photochemical reaction in the second ejector 8, and the reaction product enters the photochemical reactor 9 for a secondary reaction to ensure the purity of the product.

[0037] When the secondary reaction is carried out in the photochemical reactor 9, the pressure of the photochemical reactor 9 is controlled by the seventh control valve F7, and the gas product generated during the reaction process enters the gas-liquid separation tank 12.

[0038] When the secondary reaction is carried out in the photochemical reactor 9, it is judged by sampling whether the purity of the photochemical reaction product meets the standard. If it meets the standard, the circulation pump 10 is started, the eighth control valve F8 is opened to discharge the material from the photochemical reactor 9, the ninth control valve F9 is opened, and the photochemical reaction product is stored through the product collection pipe L3. If it does not meet the standard, the circulation pump 10 is started, the eighth control valve F8 is closed, and the unqualified photochemical reaction product re-enters the second ejector 8 for photochemical reaction after passing through the heat exchanger 11 until the purity of the photochemical reaction product meets the requirements.

[0039] The gas products generated during the reaction process enter the gas-liquid separation tank 12. After cooling, the liquid-phase crude solvent is controlled by the eleventh control valve F11 and recycled to the crude solvent storage tank through the liquid-phase outlet at the bottom of the gas-liquid separation tank 12; the gas composition at the gas-phase outlet of the gas-liquid separation tank 12 is a mixed gas of carbon dioxide and hydrogen chloride. After the mixed gas is controlled by the tenth control valve F10 and enters the hydrochloric acid absorption tower 13, water is added through the water inlet pipe at the top of the hydrochloric acid absorption tower 13 and controlled by the twelfth control valve F12. When water is used to absorb hydrogen chloride gas, the volume ratio is V(water):V(hydrogen chloride)=1:500. At this time, the hydrogen chloride gas generated during the photochemical reaction process is absorbed by the water sprayed from the top of the tower, while the carbon dioxide in the mixed gas is completely insoluble in water. The carbon dioxide after absorption treatment enters the present utility model, that is, the first ejector 2, through the carbon dioxide outlet at the top of the tower and the CO2 recovery pipe L4 in a cycle.

Claims

1. An apparatus for recycling carbon dioxide to produce industrial special isocyanates, comprising a salt-forming reactor (3), a photochemical reactor (9), and a gas-liquid separation tank (12), characterized in that: The liquid outlet pipe of the first ejector (2) is connected to the salt-forming reactor (3). The CO2 inlet pipe (L1) and the liquid outlet pipe of the pre-mixer (1) are connected to the first ejector (2). The discharge pipe at the bottom of the salt-forming reactor (3) is connected to the post-mixer (5) through a peristaltic pump (4). The liquid outlet pipe of the post-mixer (5) is connected to the reboiler (7). The outlet of the reboiler (7) is connected to the second ejector (8). The outlet of the second ejector (8) is connected to the photochemical reactor (9). The upper gas-phase pipe of the photochemical reactor (9) is connected to the gas-liquid separation tank (12). The top gas-phase port of the gas-liquid separation tank (12) is connected to the hydrochloric acid absorption tower (13). The upper gas-phase outlet of the hydrochloric acid absorption tower (13) is connected to the first ejector (2) through the CO2 recovery pipe (L4). The discharge pipe at the bottom of the photochemical reactor (9) is connected to the first heat exchanger (11) through a circulation pump (10), and the outlet of the first heat exchanger (11) is connected to the second ejector (8).

2. The device for recycling carbon dioxide to produce industrial special isocyanates according to claim 1, characterized in that: The amine raw material feed pipe is connected to the pre-mixer (1), and a third control valve (F3) is provided on the amine raw material feed pipe. The liquid outlet pipe of the second heat exchanger (14) is connected to the pre-mixer (1), and a second control valve (F2) is provided on this liquid outlet pipe. The inlet of the second heat exchanger (14) is connected to the solvent inlet pipe. The second control valve (F2) and the third control valve (F3) are controlled by DCS.

3. The device for recycling carbon dioxide to produce industrial special isocyanates according to claim 1, characterized in that: The upper part of the salt-forming reactor (3) is connected to the gas discharge pipe (L2). The gas discharge pipe (L2) is connected to the CO2 inlet pipe (L1). A first control valve (F1) is provided on the CO2 inlet pipe (L1), and a fourth control valve (F4) for controlling the pressure of the salt-forming reactor (3) is provided on the gas discharge pipe (L2). A fifth control valve (F5) for discharging materials is provided on the discharge pipe at the bottom of the salt-forming reactor (3). The first control valve (F1), the fourth control valve (F4), and the fifth control valve (F5) are controlled by DCS.

4. The device for recycling carbon dioxide to produce industrial special isocyanates according to claim 1, characterized in that: A flushing pump (6) is also connected to the post-mixer (5).

5. The device for recycling carbon dioxide to produce industrial special isocyanate according to claim 1, characterized in that: A phosgene inlet pipe is connected to the second ejector (8), and a sixth control valve (F6) for controlling the phosgene flow rate is provided on the phosgene inlet pipe. The sixth control valve (F6) is controlled by DCS.

6. The device for recycling carbon dioxide to produce industrial special isocyanate according to claim 1, characterized in that: A seventh control valve (F7) for controlling its pressure is provided on the upper gas-phase pipe of the photochemical reactor (9), and an eighth control valve (F8) for discharging materials is provided on the discharge pipe at the bottom. The seventh control valve (F7) and the eighth control valve (F8) are controlled by DCS.

7. The device for recycling carbon dioxide to produce industrial special isocyanates according to claim 1, characterized in that: A product collection pipe (L3) is also connected to the discharge pipe at the bottom of the photochemical reactor (9), and a ninth control valve (F9) for controlling the product flow rate is provided on the product collection pipe (L3). The ninth control valve (F9) is controlled by DCS.

8. The device for recycling carbon dioxide to produce industrial special isocyanates according to claim 1, characterized in that: A tenth control valve (F10) is provided on the gas-phase pipe at the top of the gas-liquid separation tank (12), and an eleventh control valve (F11) for controlling the outlet flow rate is provided on the liquid-phase pipe at the bottom; a water inlet pipe is connected to the upper part of the hydrochloric acid absorption tower (13), and a twelfth control valve (F12) is provided on the water inlet pipe; a thirteenth control valve (F13) for controlling the hydrochloric acid flow rate is provided on the hydrochloric acid discharge pipe at the bottom of the hydrochloric acid absorption tower (13); the tenth control valve (F10), the eleventh control valve (F11), the twelfth control valve (F12) and the thirteenth control valve (F13) are controlled by DCS.

9. The device for recycling carbon dioxide to produce industrial special isocyanates according to claim 1, characterized in that: A fourteenth control valve (F14) is provided on the CO2 recovery pipe (L4), and the fourteenth control valve (F14) is controlled by DCS.

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