Kettle type phosgenation reactor

Abstract

The utility model relates to a kettle type phosgenation reactor, which is characterized in that a feed pipe (L1) is arranged on one side of the upper part of a kettle body (1), a phosgene inlet pipe (L2), an inert gas inlet pipe (L3) and a gas phase outlet pipe (L4) are arranged at the top of the kettle body (1), and a discharge pipe (L5) is arranged at the bottom of the kettle body (1); the kettle body (1) is provided with an internal heating system and an external heating system, a siphon stirrer (6) is arranged in the kettle body (1), a fluid stirring device (7) is arranged at the bottom of the kettle body (1), a gas molecule filter (8) is further arranged at the top of the kettle body (1), and a liquid level meter (10) is arranged on the kettle body (1). A column type circulating heating system is arranged in the reactor, a column type multi-layer heater is constructed in the reactor, and under the participation of multiple stirring, reactants are fully and uniformly heated, the local temperature is reduced, the selectivity of products is improved, the content of phosgene in tail gas is reduced, and the production safety is ensured.

Description

Technical Field

[0001] The utility model belongs to the field of fine chemical technology equipment, and particularly relates to a kettle-type phosgenation reactor. Background Technique

[0002] Phosgene, as an important organic intermediate, has a wide variety of downstream products. Phosgene and phosgenation derivatives are widely used in engineering plastics, synthetic material additives, pesticides, pharmaceuticals, engineering plastics, polyurethane materials, and the military. China is the world's most important producer and consumer of phosgene products. Since China began to produce phosgene and its downstream application products, its production scale has increased significantly. Due to the high toxicity and potential hazards of phosgene, it has gradually become a special development resource.

[0003] A kettle reactor is a device used for chemical reactions between gas, liquid, and solid phases, commonly found in fields such as pharmaceuticals, chemistry, fertilizers, and food. Its advantages are as follows: (1) The structure of the kettle reactor is simple, easy to manufacture, has a long service life, occupies relatively little space, and can be selected as vertical or horizontal according to space requirements; (2) The kettle reactor usually adopts a closed operation method, which can reduce the volatilization of reactants and solvents, thereby improving the chemical reaction efficiency; (3) The kettle reactor can adjust parameters such as reaction temperature, pressure, and time according to different reaction requirements, facilitating users to precisely control the reaction conditions; (4) The kettle reactor can prevent the leakage of reactants and solvents, reduce the occurrence of chemical accidents, and thus ensure the life and property safety of users. Therefore, the kettle reactor is widely used in phosgenation reactions. However, the commonly used kettle reactors face the following defects: First, during the phosgenation reaction process, toluene, o-dichlorobenzene, and chlorobenzene, which have relatively high solubility for phosgene, are usually selected as solvents. However, at normal pressure and when the phosgenation reaction temperature reaches above 50 o °C, the solubility of phosgene in toluene, o-dichlorobenzene, and chlorobenzene is 0 kg / 100 kg, 21.693 kg / 100 kg, and 17.173 kg / 100 kg respectively. As a result, phosgene will quickly escape from the kettle gas-phase outlet together with the by-product gas, and the residence time of phosgene in the reaction process is short, the contact time with the reactants is short, and it is difficult to fully react; Second, before the kettle reactor carries out the photochemical reaction, it usually needs to first establish a relatively high liquid level to avoid the idling of the stirrer. However, the commonly used solvents have poor heat transfer coefficients (the heat transfer coefficients of toluene and chlorobenzene are 0.12 W / (mK) and 0.13 W / (mK) respectively), resulting in uneven heating during the reaction process, a longer heating time required, a large temperature difference between the bottom and top of the reaction kettle, the edge and inside of the reaction kettle, and too high local temperature, which is more likely to cause side reactions; Third, the utilization rate of phosgene is low, the risk coefficient of tail gas treatment is high, the treatment method is complex, and a separate tail gas treatment device needs to be established, resulting in higher production costs. Summary of the Invention

[0004] The purpose of the present utility model is to overcome the problems existing in the prior art, and to provide a kettle-type phosgenation reactor with wide applicability, fundamentally solving the fundamental problems of low phosgene utilization rate, uneven internal heat exchange in the kettle-type reactor, and high risk coefficient in tail gas treatment when the kettle-type reactor conducts phosgenation reaction.

[0005] To achieve the above purpose, the technical solution adopted by the present utility model is: a kettle-type phosgenation reactor, including a kettle body, characterized in that: a feed pipe is provided on one side of the upper part of the kettle body, a phosgene inlet pipe, an inert gas inlet pipe, and a gas outlet pipe are provided on the top of the kettle body, and a discharge pipe is installed at the bottom of the kettle body; the kettle body is provided with an internal heating system and an external heating system, a siphon stirrer is provided inside the kettle body, a fluid stirring device is provided at the bottom of the kettle, a gas molecule filter is provided on the top of the kettle body, and a liquid level gauge is provided on the kettle body.

[0006] The internal heating system includes a column-type circulating heater provided in the kettle body to make the material fully and evenly heated, a thermometer in the middle of the column-type circulating heater, and a thermometer at the bottom of the kettle. The material of the column-type circulating heater is any one of 316 stainless steel, enamel, and 304 stainless steel.

[0007] The external heating system is: a jacket is provided outside the kettle body, a medium-pressure steam inlet pipe and an outlet pipe are connected to the jacket, and a thermometer is provided on the medium-pressure steam inlet pipe.

[0008] A gas molecule filter is provided at the pipe orifice of the gas outlet pipe; the pore diameter of the gas molecule filter is less than or equal to 1.4 nm.

[0009] The gas molecule filter is a microporous structure molecular sieve or a gas molecule membrane filter.

[0010] The microporous structure molecular sieve is zeolite molecular sieve (ZSM-5), rhombohedral zeolite structure-like molecular sieve (SAPO-34), zeolite imidazolate framework structure molecular sieve (ZIF-67), microporous titanium, microporous foam carbon, ceramic molecular sieve;

[0011] For the gas molecule membrane filter, the gas molecule filter membrane is an ether sulfone membrane (PES) folding filter element, a polytetrafluoroethylene (PTFE) folding filter element, a nylon membrane (N6 / N66) folding filter element, a polyvinylidene fluoride membrane (PVDF) folding filter element, a mixed cellulose membrane (MCE) folding filter element, a polypropylene (PP) folding filter element, a glass fiber (GF) folding filter element.

[0012] The phosgene inlet pipe extends into the bottom end of the kettle body and is provided with a liquid phosgene disperser.

[0013] A manhole for easy maintenance is provided at the bottom of the kettle body.

[0014] The liquid level gauge is interlocked with the control valve on the feed pipe.

[0015] Compared with the prior art, the advantages of the present utility model are as follows:

[0016] (1) A gas molecule filtration device is installed inside the reactor. Only hydrogen chloride molecules and inert gas molecules generated by side reactions can pass through, while solvent vapor and phosgene gas molecules are difficult to pass through (the diameter of hydrogen chloride gas molecules is 0.30 nm; the diameter of carbon dioxide gas molecules is 0.33 nm; the diameter of phosgene gas molecules is 1.464 nm), ensuring that phosgene remains in the autoclave reactor, increasing the contact time with the reactants, and enabling complete reaction; the by-product hydrogen chloride is carried out of the gas phase outlet by the inert gas, avoiding affecting the reaction.

[0017] (2) A fluid stirring device is provided at the bottom of the reactor to stir the liquid inside the reaction kettle, forming a uniform clockwise liquid flow direction inside the kettle. Combined with the large siphon stirrer inside the kettle, heat exchange is sufficient;

[0018] (3) A grid-type circulation heating system is provided inside the reactor. A grid-type multi-layer heater is constructed inside the autoclave reactor. With the participation of multiple stirrings, the reactants are heated sufficiently and evenly, reducing the local temperature, increasing the selectivity of the product, reducing the content of phosgene in the tail gas, and ensuring production safety;

[0019] (4) A fluid stirring device is arranged inside the kettle, enabling the reaction to proceed at a lower liquid level, eliminating the need to use a siphon stirrer, avoiding the idling of the siphon stirrer blades, and causing excessive waste of electric energy, with strong applicability. Description of the Drawings

[0020] Figure 1 The following shows a schematic diagram of the present utility model.

[0021] In the figure: 1 - kettle body, 2 - jacket, 3 - grid-type circulation heater, 4 - thermometer in the kettle, 5 - thermometer at the bottom of the kettle, 6 - siphon stirrer, 7 - fluid stirring device, 8 - gas molecule filter, 9 - liquid phosgene disperser, 10 - liquid level gauge;

[0022] L1 - feed pipe, L2 - phosgene inlet pipe, L3 - inert gas inlet pipe, L4 - gas phase outlet pipe, L5 - discharge pipe. Detailed Embodiments

[0023] The technical solutions of this patent 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 scope of protection of this patent.

[0024] Example 1

[0025] A kettle-type phosgenation reactor, comprising a kettle body 1, characterized in that: on one side of the upper part of the kettle body 1, a feed pipe L1 is provided, on the top of the kettle body 1, a phosgene inlet pipe L2, an inert gas inlet pipe L3 and a gas-phase outlet pipe L4 are provided, and a discharge pipe L5 is installed at the bottom of the kettle body 1; the kettle body 1 is provided with an internal heating system and an external heating system, inside the kettle body 1, a siphon stirrer 6 is provided, a fluid stirring device 7 is provided at the bottom of the kettle, a gas molecular filter 8 is provided at the top of the kettle body 1, and a liquid level gauge 10 is provided on the kettle body 1.

[0026] The internal heating system includes a grid-type circulating heater 3 provided inside the kettle body 1 for enabling the material to be heated sufficiently and evenly. A thermometer 4 in the middle of the grid-type circulating heater 3 and a thermometer 5 at the bottom are provided. The material of the grid-type circulating heater is 316 stainless steel.

[0027] The external heating system is: an outer jacket 2 is provided outside the kettle body 1, a medium-pressure steam inlet pipe and an outlet pipe are connected to the outer jacket 2, and a thermometer is provided on the medium-pressure steam inlet pipe.

[0028] A gas molecular filter 8 is provided at the orifice of the gas-phase outlet pipe L4; the pore diameter of the gas molecular filter 8 is less than or equal to 1.4 nm.

[0029] The gas molecular filter 8 is a microporous structure molecular sieve or a gas molecular membrane filter.

[0030] The microporous structure molecular sieve is zeolite molecular sieve (ZSM-5), rhomboid zeolite structure-like molecular sieve (SAPO-34), zeolite imidazolate framework structure molecular sieve (ZIF-67), microporous titanium, microporous foam carbon, ceramic molecular sieve;

[0031] For the gas molecular membrane filter, its gas molecular filter membrane is an ether sulfone membrane (PES) folding filter element, a polytetrafluoroethylene (PTFE) folding filter element, a nylon membrane (N6 / N66) folding filter element, a polyvinylidene fluoride membrane (PVDF) folding filter element, a mixed cellulose membrane (MCE) folding filter element, a polypropylene (PP) folding filter element, a glass fiber (GF) folding filter element.

[0032] The phosgene inlet pipe L2 extends into the bottom end of the kettle body 1 and is provided with a liquid phosgene disperser 9.

[0033] A manhole for easy maintenance is provided at the bottom of the kettle body 1.

[0034] The liquid level gauge 10 is interlocked with the control valve F on the feed pipe L1.

[0035] The operation process of the kettle-type phosgenation reactor of this patent will be explained below in the form of examples. (Taking the production of salicylonitrile by the phosgenation method as an example)

[0036] (1) After the pre - placed material ratio is completed, the mixed material is added to the kettle - type phosgenation reactor through the feed pipe L1, covering the fluid stirring device 7 at the bottom of the kettle. In order to improve the solubility of salicylamide and avoid the precipitation of salicylamide, the fluid stirring device 7 is turned on to make the material at the bottom of the kettle flow clockwise in the upper and lower liquid levels. At the same time, the material is continuously added. After the liquid level in the kettle reaches 80%, the siphon stirrer 6 in the kettle is turned on, so as to form a uniform stirring system, ensure the uniform mixing of the materials inside the reaction kettle, accelerate the heat transfer speed, and increase the contact area between the materials for the phosgenation reaction.

[0037] (2) Turn on the column - type circulating heater 3 and simultaneously introduce medium - pressure steam into and outside the kettle - type reactor. Since the column - type circulating heater 3 has multi - layer heating and the liquid flow direction is uniform, it can ensure that the materials are heated evenly and at the same time reduce the time required for the heating process. After heating to 105 o °C, open the gas molecular filter 8 and open the phosgene inlet pipe L2 to introduce phosgene.

[0038] (3) The phosgene passes through the liquid phosgene disperser 9 to evenly disperse the phosgene gas molecules at the bottom of the entire kettle - type reactor. At the same time, open the inert gas inlet pipe L3, and weaken the escape speed of the phosgene gas molecules through the pressure of the inert gas, and continuously introduce nitrogen during the reaction to take the by - product hydrogen chloride away from the reaction system. Calculate the usage amount of phosgene and the reaction time according to the feed sample of salicylamide in the material. At the same time, due to the opening of the gas molecular filter 8, phosgene will continuously exist in the kettle - type phosgenation reactor, ensuring the utilization rate of phosgene and having extremely high value in energy - saving and innovation.

[0039] (4) After the phosgenation reaction is completed, close the phosgene inlet pipe L2, close the siphon stirrer 6 in the kettle, close the steam heating system, and close the fluid stirring device 7. Open the discharge pipe L5, discharge the material, then close the gas molecular filter 8, and purge the kettle - type phosgenation reactor through the inert gas inlet pipe L3. At the same time, use compressed air to press out the condensate in the heating system of the kettle - type reactor and switch to circulating cooling water to cool down the reaction system. So as to facilitate subsequent continuous reaction (toluene can be added only when the temperature in the kettle - type reactor is < 70 o °C).

[0040] After the reaction is completed, if rapid cooling is required, medium - pressure steam can be replaced by circulating cooling water to cool the inside and outside of the kettle - type reactor simultaneously, so as to improve production efficiency and enhance the versatility of the kettle - type reactor.

Claims

1. A kettle-type phosgenation reactor, comprising a kettle body (1), characterized in that: On one side of the upper part of the kettle body (1), a feed pipe (L1) is provided. On the top of the kettle body (1), a phosgene inlet pipe (L2), an inert gas inlet pipe (L3), and a gas-phase outlet pipe (L4) are provided. At the bottom of the kettle body (1), a discharge pipe (L5) is installed; the kettle body (1) is provided with an internal heating system and an external heating system. Inside the kettle body (1), a siphon stirrer (6) is provided, a fluid stirring device (7) is provided at the bottom of the kettle, a gas molecule filter (8) is provided at the top of the kettle body (1), and a liquid level gauge (10) is provided on the kettle body (1).

2. The kettle-type phosgenation reactor according to claim 1, wherein: The internal heating system includes a grid-type circulating heater (3) provided inside the kettle body (1) to make the material be heated fully and evenly. A thermometer in the middle of the kettle (4) is provided in the middle of the grid-type circulating heater (3), and a thermometer at the bottom of the kettle (5) is provided at the bottom.

3. The autoclave phosgenation reactor according to claim 1, wherein: The external heating system is: a jacket (2) is provided outside the kettle body (1). A medium-pressure steam inlet pipe and an outlet pipe are connected to the jacket (2), and a thermometer is provided on the medium-pressure steam inlet pipe.

4. The autoclave phosgenation reactor according to claim 1, wherein: A gas molecule filter (8) is provided at the pipe orifice of the gas-phase outlet pipe (L4); the pore diameter of the gas molecule filter (8) is less than or equal to 1.4 nm.

5. The autoclave phosgenation reactor according to claim 4, characterized in that: The gas molecule filter (8) is a microporous structure molecular sieve or a gas molecule membrane filter.

6. The autoclave phosgenation reactor according to claim 5, characterized in that: The microporous structure molecular sieve is a zeolite molecular sieve, a zeolite-like rhombic zeolite structure molecular sieve, a zeolite imidazolate framework structure molecular sieve, a microporous titanium, a microporous foam carbon, or a ceramic molecular sieve; For the gas molecule membrane filter, its gas molecule filter membrane is an ether sulfone membrane folding filter element, a polytetrafluoroethylene folding filter element, a nylon membrane folding filter element, a polyvinylidene fluoride membrane folding filter element, a mixed cellulose membrane folding filter element, a polypropylene folding filter element, or a glass fiber folding filter element.

7. The autoclave phosgenation reactor according to claim 1, wherein: The phosgene inlet pipe (L2) extends into the bottom end of the kettle body (1), and a liquid phosgene disperser (9) is provided.

8. A kettle-type phosgenation reactor according to claim 1, characterized in that: A manhole for easy maintenance is provided at the bottom of the kettle body (1).

9. The autoclave phosgenation reactor according to claim 1, wherein: The liquid level gauge (10) is interlocked with the control valve (F) on the feed pipe (L1).

10. A kettle-type phosgenation reactor according to claim 2, characterized in that: The material of the grid-type circulating heater (3) is any one of 316 stainless steel, enamel, and 304 stainless steel.

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