CN218131815U - Phosgenation reaction degasser - Google Patents

Abstract

The utility model relates to a phosgenation reaction degasser, it includes one or more swirler, and the swirler includes: the shell is provided with a separation cavity and a liquid phase discharge hole communicated with the separation cavity, and the liquid phase discharge hole is arranged at the bottom of the shell; the cyclone mechanism is arranged at the upper part of the shell and positioned above the separation cavity, the cyclone mechanism is provided with a cyclone generating channel and a heating module for heating fluid in the cyclone generating channel, the cyclone generating channel is provided with an inlet end and an outlet end lower than the inlet end, and the outlet end is communicated with the separation cavity; the photochemical liquid feeding pipe is communicated with the inlet end to pump photochemical liquid into the rotation making channel; and the gas phase overflow pipe is inserted into the upper part of the shell, and the lower end of the gas phase overflow pipe extends into the separation cavity. The utility model provides a phosgenation reaction degasser can reduce the double-phase degree of mixing back of gas-liquid.

Description

Phosgenation reaction degasser

Technical Field

The utility model belongs to the technical field of the phosgenation, concretely relates to phosgenation reaction degasser.

Background

The synthesis of isocyanates by gas-phase phosgenation has been described for a number of times, and the preparation of isocyanates, for example MDI, TDI, HDI, IPDI and the like, is based on the phosgenation of amines with excess phosgene under high-temperature conditions to give isocyanates and hydrogen chloride, which are removed by work-up to give hydrogen chloride, phosgene, solvents, low-boiling components and high-boiling components.

In the reaction process of synthesizing isocyanate by gas phase phosgenation, intermediate carbamyl chloride is an important component accompanying reaction liquid, crude product and intermediate product, and isocyanate can be prepared by decomposing carbamyl chloride. At present, research on a method for synthesizing isocyanate by a gas phase phosgenation method is mainly focused on a reactor, while research on photochemical liquid degassing (mainly comprising hydrogen chloride and phosgene) is very little, the coexistence of the product isocyanate, the hydrogen chloride and the phosgene can cause side reaction, on one hand, the yield is reduced, the cost is increased, on the other hand, in the post-treatment process, a large amount of solid can be enriched in equipment, the main components are acyl chloride substances and a small amount of urea substances, the subsequent vacuum unit and the like can be affected, the continuous and stable production is difficult, frequent stopping of the device is required, a large amount of man-hours are consumed, the system is cleaned and maintained, and the maintenance operation environment is severe due to the fact that a large amount of isocyanate monomers are contained in the solid material.

At present, the photochemical liquid is degassed by adopting a conventional degassing tower and reboiler circular heating mode, the defects of high back mixing degree of gas phase and liquid phase, long retention time and the like exist, and the side reaction is easy to occur, the equipment is blocked, and the continuous production is influenced.

Disclosure of Invention

The utility model aims at providing a phosgenation reaction degasser, reduce the double-phase back mixing degree of gas-liquid.

In order to achieve the above purpose, the utility model adopts the technical scheme that:

a phosgenation reaction degassing apparatus comprising one or more cyclones, said cyclones comprising:

the device comprises a shell, a liquid-phase separation device and a liquid-phase separation device, wherein the shell is provided with a separation cavity and a liquid-phase discharge hole communicated with the separation cavity, and the liquid-phase discharge hole is formed in the bottom of the shell;

the cyclone mechanism is arranged at the upper part of the shell and is positioned above the separation cavity, the cyclone mechanism is provided with a cyclone generating channel and a heating module for heating fluid in the cyclone generating channel, the cyclone generating channel is provided with an inlet end and an outlet end lower than the inlet end, and the outlet end is communicated with the separation cavity;

the photochemical liquid feeding pipe is communicated with the inlet end so as to pump photochemical liquid into the rotation making channel;

a gas phase overflow pipe inserted into the upper portion of the housing, a lower end of the gas phase overflow pipe extending into the separation chamber.

Preferably, the swirl generating passage extends spirally around a longitudinal centerline of the housing, which passes through the liquid phase discharge port.

Furthermore, the gas phase overflow pipe extends up and down along the longitudinal center line of the shell, the center line of the gas phase overflow pipe is superposed with the longitudinal center line of the shell, and the rotation making channel surrounds the periphery of the gas phase overflow pipe.

Still further, the lower portion of the gas phase overflow tube comprises an outer tube extending up and down and a skirt extending obliquely downward and outward from a lower edge of the outer tube.

Further, a connecting portion inserted into the lower end of the outer tube and detachably connected with the outer tube is connected to the upper edge of the skirt.

Still further, the gas phase overflow pipe further comprises a telescopic inner pipe, one end part of the inner pipe is detachably connected with the outer pipe, and one end part of the outer pipe is connected to the tail gas recovery and treatment device.

Preferably, the cyclone further comprises an inner cone member, the inner cone member is arranged at the lower part of the separation chamber, the axis of the inner cone member is coincident with the longitudinal center line of the shell, and the bottom surface of the inner cone member faces downwards.

Furthermore, the separation cavity comprises a cylindrical section and a conical section which are arranged from top to bottom, the lower end of the gas phase overflow pipe extends into the cylindrical section, and the inner conical part is arranged at the lower part of the conical section.

Preferably, the heating module includes a heating medium passage having a heating medium inlet and a heating medium outlet, the heating medium inlet being lower than the heating medium outlet; the upper part of the shell is provided with a jacket, and the spiral channel and the heating medium channel are formed in the jacket.

Preferably, the phosgenation reaction degassing device comprises two cyclones, namely a primary cyclone and a secondary cyclone; a first feeding pipe of the primary cyclone is connected to a quenching device of phosgenation reaction, a liquid phase discharge port of the primary cyclone is connected to a buffer tank through a first discharge pipeline, and a gas phase overflow pipe of the primary cyclone is connected to a tail gas recovery processing device; and a second feeding pipe of the secondary cyclone is connected to the buffer tank, a liquid phase discharge port of the secondary cyclone is connected to the buffer tank through a second discharge pipe or connected to downstream through a third discharge pipe, and a gas phase overflow pipe of the secondary cyclone is connected to the tail gas recovery processing device.

Because of the application of the technical scheme, compared with the prior art, the utility model has the following advantages:

the utility model provides a phosgenation reaction degasser can shorten the dwell time of gaseous phases such as hydrogen chloride in photochemical liquid, and the double-phase back mixing degree of gas-liquid reduces, has reduced the formation of solid accessory substance and chloro-substituted by-product, avoids blockking up equipment or pipeline and influences normal serialization production, improves the product yield, and device itself can realize the automatically cleaning, avoids blockking up, suitably is applied to and carries out photochemical liquid degasification in the equipment of gaseous phase phosgenation preparation isocyanate.

Drawings

FIG. 1 is a schematic diagram of a phosgenation reactive degassing apparatus according to an embodiment of the present invention;

fig. 2 is a schematic structural view of one of the cyclones according to an embodiment of the present invention;

fig. 3 is a schematic view of a gas phase overflow pipe structure according to an embodiment of the present invention.

Wherein, 1a, a primary cyclone; 1b, a secondary cyclone; 4. a tail gas recovery processing device; 5. a quenching device; 6. a buffer tank; 7. a pump; 81. a first feeding pipe; 82. a first discharge pipe; 83. a second feeding pipe; 84. a second discharge pipe; 85. a third discharge pipe;

11. a housing; 111. a separation chamber; 1111. a cylindrical section; 1112. a conical section; 112. a liquid phase discharge port; 12. a swirling mechanism; 121. making a rotary channel; 1211. an inlet end; 1212. an outlet end; 122. a heating module; 1221. a heating medium inlet; 1222. a heating medium outlet; 1223. a heat medium passage; 13. feeding actinic liquid into a pipe; 14. a gas phase overflow pipe; 141. an outer tube; 142. a skirt edge; 143. a connecting portion; 144. an inner tube; 15. an inner cone; 151. a bottom surface; 16. a jacket; 17. and (7) a baffle plate.

Detailed Description

The technical solutions of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As described above, in view of the defects of the prior art, the inventors of the present invention have made extensive studies and extensive practices to propose a technical solution of the present invention. The following detailed description will more fully understand the invention. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed embodiment.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In the event of a conflict or inconsistency between a definition used herein and that loaded in another publication, the definition used herein shall prevail.

As shown in fig. 1, a phosgenation reaction apparatus according to the present embodiment mainly includes a primary cyclone 1a and a secondary cyclone 1b. In a specific application example, photochemical liquid after isocyanate preparation reaction is subjected to gas-liquid separation sequentially through a primary cyclone 1a and a secondary cyclone 1 b; wherein, the primary cyclone 1a is not provided with circulation and is used for rapidly removing hydrogen chloride and a part of phosgene to realize rapid separation of the hydrogen chloride; the secondary cyclone 1b is provided with circulation to separate phosgene thoroughly. In the embodiment, two cyclones are preferably used, and a plurality of cyclones can also be used, so that in the reaction process of synthesizing the isocyanate by gas phase phosgenation, timely dehydrochlorination is beneficial to the reaction to move towards the direction of the isocyanate, and simultaneously, the acyl chloride substances are reduced, and the blockage of equipment pipelines is avoided.

The specific structure of one of the cyclones in this embodiment will be described as follows:

as shown in fig. 2, the cyclone (the primary cyclone 1a or the secondary cyclone 1 b) includes a housing 11 having a separation chamber 111 and a liquid phase outlet 112 communicating with the separation chamber 111, the liquid phase outlet 112 is specifically disposed at the bottom of the housing 11, and a longitudinal center line of the housing 11 passes through the liquid phase outlet 112. The separation chamber 111 includes a cylindrical section 1111 and a conical section 1112 arranged from top to bottom.

The cyclone further includes a cyclone mechanism 12 disposed at an upper portion of the housing 11 and above the separation chamber 111, and the cyclone mechanism 12 has a cyclone creating passage 121 and a heating module 122 for heating fluid in the cyclone creating passage 121. The swirl-inducing channel 121 has an inlet end 1211 and an outlet end 1212 lower than the inlet end 1211, the outlet end 1212 communicating with the separation chamber 111, the swirl-inducing channel 121 extending helically around the longitudinal centre line of the housing 11. The heating module 122 includes a heating medium passage 1223 having a heating medium inlet 1221 and a heating medium outlet 1222, the heating medium inlet 1221 being lower than the heating medium outlet 1222, the heating medium passage 1223 having a plurality of substantially horizontal and staggered baffles 17 therein, the baffles 17 being substantially arcuate or crescent shaped to facilitate heat exchange. The cyclone further comprises a photochemical liquid feeding pipe 13 which is communicated with the inlet end 1211 of the cyclone-making channel 121 to pump photochemical liquid into the cyclone-making channel 121. Specifically, in the present embodiment, jacket 16 is provided in the upper portion of casing 11, and heating medium passage 1223 is specifically formed by jacket 16.

The cyclone further comprises a gas phase overflow pipe 14 inserted in the upper part of the housing 11, the lower end of the gas phase overflow pipe 14 extending into the separation chamber 111; the gas phase overflow pipe 14 extends up and down along the longitudinal central line of the shell 11, the central line of the gas phase overflow pipe 14 is coincident with the longitudinal central line of the shell 11, and the cyclone channel 121 surrounds the periphery of the gas phase overflow pipe 14. As shown in fig. 3, the lower portion of the gas phase overflow pipe 14 includes an outer pipe 141 extending upward and downward and a skirt 142 extending obliquely downward and outward from the lower edge of the outer pipe 141, the upper edge of the skirt 142 is connected to a connecting portion 143, and the connecting portion 143 is inserted into the lower end of the outer pipe 141 and detachably connected to the outer pipe 141. The gas phase overflow pipe 14 further includes a telescopic inner pipe 144, an end portion of the inner pipe 144 is detachably connected to the outer pipe 141, an end portion of the outer pipe 141 is connected to the off-gas recovery processing device 4, and a lower end of the gas phase overflow pipe 14 extends into the cylindrical section 1111.

The cyclone further comprises an inner cone 15, the inner cone 15 being arranged at the lower part of the separation chamber 111 with the axis of the inner cone 15 coinciding with the longitudinal centre line of the housing 11, the inner cone 15 having a downwardly facing bottom surface 151, the inner cone 15 being arranged at the lower part of the conical section 1112.

In a specific application example, the mass fraction of HDI in the HDI photochemical liquid is 20-50%, such as 25%; the mass fraction of phosgene is 1.0-1.5%; the mass fraction of the hydrogen chloride is 0.5 to 1 percent; the mass fraction of the monochloro isocyanate is 0.5-4%, for example 0.5-1%, and the rest is solvent. The reacted photochemical liquid enters an inlet end 1211 of a cyclone making channel 121 through a photochemical liquid feeding pipe 13, the reaction is carried out through heating, HCl and NCO are generated through reaction, the material has a strong initial rotating speed at the inlet end 1211 through the cyclone making channel 121, the liquid phase part is settled along the wall of a cylindrical section 1111 in a cyclone mode under the comprehensive action of gravity and centrifugal force, the material passes through a conical section 1112 and then reaches an outlet at the bottom, certain rotating shearing turbulent motion is beneficial to removing hydrogen chloride from amino acyl chloride in the cyclone making process, and then the liquid phase product is subjected to downstream conventional post-treatment; and the gas phase part (hydrogen chloride, phosgene, etc.) with lower density moves along the radial direction under the action of centrifugal force, migrates to the central axis of the cyclone, spirally rises through the gas phase overflow pipe 14, and overflows at the top overflow port (namely the top of the inner pipe 144), and the gas phase and the liquid phase are separated efficiently due to the density difference. In actual operation, a low-pressure area is generated in the center of the cyclone (near the axial center), all diffused or dissolved gases in the feeding materials are gathered towards the center, a rotating gas column is formed in the center of the cyclone, then the gases overflow upwards, the gas at the top overflow outlet is conveyed to a vacuum unit through a condenser, and the gas removal is facilitated under the condition of micro negative pressure (the absolute pressure is 850-950 mbar).

The material directly enters the spiral making channel 121 after being fed from the photochemical liquid feeding pipe 13, so that the buffer amount of the photochemical liquid can be reduced, the detention time of the material at an inlet is shortened, and the side reaction is avoided. Make and revolve passageway 121 and design into similar spiral plate heat exchanger structure and immerse in the hot fluid, it still is provided with bow-shaped (moon-shaped) baffling board 17 in the passageway 121 to make to revolve, the material high velocity of flow in baffling board 17, the whirl turbulent motion state of strong centrifugal force makes the convection heat transfer coefficient of fluid great, do benefit to high-efficient heat transfer, also do benefit to the decomposition temperature of accurate control carbamoyl chloride, can in time carry out gas-liquid separation at separation chamber 111, also can effectively avoid conventional degasification method circulation heating kettle liquid, can't in time carry out gas-liquid separation and lead to backmixing, cause the condition of equipment such as side reaction, jam tower ware, vacuum unit.

The skirt 142 that extends that inclines out is designed to the lower limb of gaseous phase overflow pipe 14, can effectively prevent the short circuit, avoids the material to get into cylinder section 1111 from making and revolves the passageway 121 when, and some materials do not flow downwards and carry out the whirl degasification and handle, but receive the ascending air current influence of axial, rise along gaseous phase exit tube pipe wall and overflow, lead to acyl chloride class and urea class solid matter accumulation, block up equipment.

If the lower end of the gas phase overflow pipe 14 extends into the cylindrical section 1111, a short circuit is easily caused, and if the lower end of the gas phase overflow pipe extends into the cylindrical section 1111 too much, redundant spaces at the upper right and upper left of the skirt 142 are easily caused to be large, so that gas flow is disturbed, and degassing efficiency is affected. Therefore, as shown in fig. 2, the gas phase overflow pipe 14 is divided into an outer pipe 141 extending vertically, a telescopic inner pipe 144, a connecting portion 143, and a skirt 142, one end of the inner pipe 144 is detachably connected to the outer pipe 141 in a screw-threaded manner, and the depth of the gas phase overflow pipe 14 inserted into the separation chamber 111 can be adjusted by adjusting the telescopic amount of the inner pipe 144, so that the height of the gas phase overflow pipe 14 can be adjusted according to different productivity conditions (the flow rate of the material is high at high productivity, the extending length can be increased, and the flow rate of the material is low at low productivity, the extending length can be shortened). In addition, the detachable design of inner tube 144 and outer tube 141 facilitates maintenance and cleaning after long-term solids accumulation.

Referring to fig. 1, a first feeding pipe 81 of the primary cyclone 1a is connected to the quenching device 5 for phosgenation reaction, a liquid phase discharge port is connected to the buffer tank 6 through a first discharge pipe 82, and a gas phase overflow pipe 14 is connected to the tail gas recovery processing device 4. The second feeding pipe 83 of the secondary cyclone 1b is connected to the buffer tank 6, the liquid phase discharge port is connected to the buffer tank 6 through the second discharge pipe 84 or connected to downstream through the third discharge pipe 85, the gas phase overflow pipe 14 of the secondary cyclone 1b is connected to the tail gas recovery processing device 4, and the material discharged from the second discharge pipe 84 passes through the buffer tank 6, passes through the pump 7, and reenters the secondary cyclone 1b through the second feeding pipe 83 for further separation.

To sum up, the utility model provides a phosgenation reaction degasser can shorten the dwell time of gaseous phases such as hydrogen chloride in photochemical liquid, and the double-phase backmixing degree of gas-liquid reduces, has reduced the formation of solid by-product and chloro byproduct, avoids blockking up equipment or pipeline and influences normal serialization production, improves the product yield, and device itself can realize the automatically cleaning, avoids blockking up, suitably is applied to and carries out photochemical liquid degasification in the equipment of gaseous phosgenation method preparation isocyanate.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. A phosgenation reaction degassing apparatus comprising one or more cyclones, said cyclones comprising:

the device comprises a shell, a liquid phase separation device and a liquid phase separation device, wherein the shell is provided with a separation cavity and a liquid phase discharge hole communicated with the separation cavity, and the liquid phase discharge hole is formed in the bottom of the shell;

the cyclone mechanism is arranged at the upper part of the shell and is positioned above the separation cavity, the cyclone mechanism is provided with a cyclone generating channel and a heating module for heating fluid in the cyclone generating channel, the cyclone generating channel is provided with an inlet end and an outlet end lower than the inlet end, and the outlet end is communicated with the separation cavity;

the photochemical liquid feeding pipe is communicated with the inlet end so as to pump photochemical liquid into the rotation making channel;

a gas phase overflow pipe inserted into the upper portion of the housing, a lower end of the gas phase overflow pipe extending into the separation chamber.

2. A phosgenation reaction degassing apparatus according to claim 1 wherein the swirl inducing passage extends helically about the longitudinal centerline of the housing which passes through the liquid phase discharge outlet.

3. A phosgenation reaction degassing apparatus according to claim 2, wherein the gas phase overflow pipe extends up and down along the longitudinal centerline of the housing, and the centerline of the gas phase overflow pipe and the longitudinal centerline of the housing coincide, and the swirl inducing channel surrounds the periphery of the gas phase overflow pipe.

4. A phosgenation reaction degassing apparatus according to claim 3 wherein the lower portion of the gas phase overflow pipe includes an outer pipe extending upwardly and downwardly and a skirt extending obliquely downwardly and outwardly from the lower edge of the outer pipe.

5. A phosgenation reaction degassing apparatus according to claim 4 in which the upper edge of the skirt is connected to a connecting portion which is inserted into the lower end of the outer tube and is detachably connected to the outer tube.

6. A phosgenation reaction degassing apparatus according to claim 4 wherein the gas phase overflow tube further comprises a telescopic inner tube, one end of the inner tube and the outer tube being detachably connected, one end of the outer tube being connected to a tail gas recovery treatment apparatus.

7. A phosgenation reaction degassing apparatus according to claim 1 wherein the cyclone further comprises an internal conical member disposed at the lower portion of the separation chamber and having its axis coincident with the longitudinal centerline of the housing, the bottom surface of the internal conical member facing downwardly.

8. A phosgenation reaction degassing apparatus according to claim 7 wherein the separation chamber comprises a cylindrical section and a conical section arranged from top to bottom, the lower end of the gas phase overflow pipe extends into the cylindrical section and the internal conical member is arranged at the lower part of the conical section.

9. The phosgenation reaction degasser of claim 1, wherein the heating module includes a heating medium channel having a heating medium inlet and a heating medium outlet, the heating medium inlet being lower than the heating medium outlet; the upper part of the shell is provided with a jacket, and the spiral channel and the heating medium channel are formed in the jacket.

10. A phosgenation degassing apparatus as claimed in claim 1 wherein the phosgenation degassing apparatus includes two said cyclones, a primary cyclone and a secondary cyclone respectively; a first feeding pipe of the primary cyclone is connected to a quenching device of phosgenation reaction, a liquid phase discharge port of the primary cyclone is connected to a buffer tank through a first discharge pipeline, and a gas phase overflow pipe of the primary cyclone is connected to a tail gas recovery processing device; and a second feeding pipe of the secondary cyclone is connected to the buffer tank, a liquid phase discharge port of the secondary cyclone is connected to the buffer tank through a second discharge pipe or connected to downstream through a third discharge pipe, and a gas phase overflow pipe of the secondary cyclone is connected to the tail gas recovery processing device.

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