A gas-phase phosgenation reactor and its application

Abstract

The present invention discloses a gas-phase phosgenation reactor and its application. The gas-phase phosgenation reactor includes a reactor main body, which includes a feeding unit, a first connection unit having a first reaction channel, one or more mixing units, a second connection unit having a second reaction channel, and a discharging unit connected in sequence; the feeding unit has a first main channel and a plurality of first side channels, the inlet of the first main channel is communicated with a first feeding port, the inlets of the first side channels are communicated with a second feeding port, the outlets of the first main channel and the plurality of first side channels converge and are communicated with the first reaction channel of the first connection unit; the mixing unit has a plurality of shunt channels; the discharging unit has a second main channel and a plurality of second side channels, the inlets of the second main channel and the second side channels are communicated with the second reaction channel, and the outlets converge with each other. The present invention can reduce the probability of generating by-products while ensuring a good mixing effect.

Description

Technical Field

[0001] The present invention relates to a gas-phase phosgenation reactor and its application, in particular to a method for preparing isocyanate using the gas-phase phosgenation reactor. Background Art

[0002] Currently, the production of isocyanate is mainly achieved by reacting phosgene with organic amine to form isocyanate and hydrogen chloride, and then separating isocyanate from hydrogen chloride. The reaction between phosgene and organic amine features a fast reaction rate and a large heat release. If the mixing speed is slow, a large amount of coke will easily be generated. The accumulation of coke will cause wall coking and agglomeration in the reactor, and eventually block the reactor. Therefore, it is necessary to quickly mix phosgene and amine to avoid the formation of solid substances in the reactor and extend the operation cycle of the reactor. At the same time, due to the large heat release of the reaction, it is necessary to control the reaction temperature to avoid the formation of too many hot spots and increase the occurrence of side reactions.

[0003] In some reactors for preparing isocyanate, a reactor that divides amine, inert medium, and phosgene into three layers of dilute gases from the inside to the outside and enters the mixing zone of the reactor in the same direction for mixing and reaction, but this reactor has a problem of poor mixing effect, resulting in an extended mixing time and thus easily generating a large amount of coke.

[0004] There are also some microchannel-based reactors that pre-disperse phosgene and amine vapor through these microchannels and mix and react at the outlet of the microchannels. This structure is conducive to reaction mixing, and by paralleling multiple microreactors, an enlarged reactor can be simply obtained; however, these feed pipelines are particularly prone to solid deposition and blockage.

[0005] There are also some reactors equipped with baffle plates. A conical baffle is installed in the tubular reactor to generate turbulence, enhance the mixing effect, enable the gas reactants to obtain a turbulent state at a lower flow rate, and shorten the mixing distance of the reactants. However, it is easy to form backmixing and increase the probability of side reactions. Summary of the Invention

[0006] Aiming at the above problems, the purpose of the present invention is to provide a gas-phase phosgenation reactor, which can ensure a good mixing effect while reducing the probability of generating by-products.

[0007] Another object of the present invention is to provide a method for preparing isocyanate using the gas-phase phosgenation reactor.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A gas-phase phosgenation reactor, comprising a reactor main body, which includes a feeding unit, a first connection unit having a first reaction channel, one or more mixing units, a second connection unit having a second reaction channel, and a discharging unit, which are arranged in sequence from the rear to the front;

[0010] The feeding unit has a first main channel and a plurality of first side channels. The plurality of first side channels are arranged beside the first main channel. The whole or at least part of each first side channel is configured to have a bent shape capable of preventing fluid from flowing from its outlet to its inlet. The inlet of the first main channel is communicated with a first feed port, the inlet of the first side channel is communicated with a second feed port, the first feed port and the second feed port are used for respectively introducing two reaction raw materials for the gas-phase phosgenation reaction, and the outlet of the first main channel and the outlets of the plurality of first side channels converge and are communicated with the first reaction channel of the first connection unit;

[0011] The mixing unit has a plurality of shunt channels. The inlet of each shunt channel is communicated with the first reaction channel, and the outlets of the plurality of shunt channels converge and are communicated with the second reaction channel of the second connection unit;

[0012] The discharging unit has a second main channel and a plurality of second side channels. The plurality of second side channels are arranged beside the second main channel. The second side channel is configured to have a bent shape capable of preventing fluid from flowing from its outlet to its inlet. The inlet of the second main channel and the inlets of the plurality of second side channels are communicated with the second reaction channel, and the outlet of the second main channel and the outlets of the plurality of second side channels converge.

[0013] Preferably, the second feed port is annular and surrounds the first feed port, and the second feed port is used for introducing phosgene.

[0014] Preferably, the first side channel, the shunt channel and the second side channel respectively include an inlet section extending obliquely outward from their respective inlets and an outlet section extending obliquely outward from their respective outlets, and the inlet section and the outlet section are connected by an arc section.

[0015] More preferably, the inlet section of the first side channel gradually inclines backward and outward from its inlet, and the outlet section of the first side channel gradually inclines backward and outward from its outlet; the inlet section of the shunt channel gradually inclines forward and outward from its inlet, and the outlet section of the shunt channel gradually inclines forward and outward from its outlet; the inlet section of the second side channel gradually inclines backward and outward from its inlet, and the outlet section of the second side channel gradually inclines backward and outward from its outlet.

[0016] Further, the arc section of the first side channel is located at the rear side of its inlet section and outlet section, the arc section of the shunt channel is located at the front side of its inlet section and outlet section, and the arc section of the second side channel is located at the rear side of its inlet section and outlet section.

[0017] More preferably, the included angle between the extending direction of the inlet section or the outlet section and the length direction of the reactor body is less than 90 degrees, and the first main channel, the first reaction channel, the second main channel and the second reaction channel respectively extend along the length direction of the reactor body and are aligned.

[0018] Further, the included angle is between 15 degrees and 90 degrees, especially between 30 degrees and 60 degrees.

[0019] Further, the number of the first side channels, the shunt channels and the second side channels is 2 to 6 and they are arranged at intervals along the circumferential direction of the reactor body. The number of the first side channels, the shunt channels and the second side channels can be the same or different, and preferably is 2 to 3.

[0020] Further, the ratio of the arc radius of the inner edge to the arc radius of the outer edge of each arc section is 1:2 to 6.

[0021] Preferably, the number of the mixing units is one, and the first reaction channel and the second reaction channel are only connected by a plurality of the shunt channels; or, the number of the mixing units is 2 to 5, and two adjacent mixing units are connected by a third connection unit having a third reaction channel, and the first reaction channel and the second reaction channel are connected through the shunt channels and the third reaction channel.

[0022] Preferably, the reactor body is formed by a plurality of pipes, and the plurality of pipes include at least two straight pipes and a plurality of bent pipes. The rear part of the first straight pipe is internally inserted with an inner pipe, at least a part of the first main channel is the lumen of the inner pipe, the first side channel includes the lumen of the bent pipe and the cavity between the first straight pipe and the inner pipe, the first reaction channel is formed in the front part of the first straight pipe, the first feed port is formed in the rear end part of the inner pipe, and the second feed port is formed between the rear end part of the inner pipe and the rear end part of the first straight pipe; the second reaction channel and the second main channel are formed in another straight pipe, and the shunt channel and the second side channel are respectively formed by the bent pipe.

[0023] Preferably, the gas-phase phosgenation reactor further includes a shell capable of placing a cooling medium, the reactor body is arranged in the shell, and there is also a discharge port on the shell, and the outlets of the second main channel and the second side channel converge and are communicated to the discharge port.

[0024] More preferably, the cooling medium is a liquid-phase inert solvent, including but not limited to: toluene, xylene, chlorobenzene, and orthodichlorobenzene.

[0025] The gaseous-phase amine includes but not limited to: 1,6-hexanediamine (HDA), 3,5-trimethyl-5-aminomethyl cyclohexane (IPDA), 4,4'-diaminodicyclohexylmethane diamine, 1,3-cyclohexanedimethanamine, methylcyclohexanediamine, trimethylhexanediamine, pentanediamine, diphenylmethane diamine, toluene diamine, etc.

[0026] The present invention also adopts the following technical solution:

[0027] A method for preparing isocyanate, using the gaseous-phase phosgenation reactor as described above, introducing the gaseous-phase amine into the first main channel through the first feed port, introducing phosgene into a plurality of the first side channels through the second feed port, enabling the gaseous-phase amine and phosgene to enter the first reaction channel for preliminary reaction, then being shunted through a plurality of the shunt channels and further mixed and reacted in the second reaction channel, and then being discharged after being shunted and collected through the second main channel and a plurality of the second side channels.

[0028] Preferably, a cooling medium is introduced into the housing, the reactor main body is arranged in the housing, and the temperature of the cooling medium in the housing is controlled to be 5 - 30 °C lower than the reaction temperature of the gaseous-phase amine and phosgene.

[0029] More preferably, the cooling medium is a liquid-phase inert solvent, a positive pressure is maintained in the housing, and the liquid-phase inert solvent vaporizes or heats up to take away the heat of the reactor main body.

[0030] Preferably, a quenching agent is used to quench the reactant discharged from the discharging unit to remove phosgene and obtain the target product.

[0031] Preferably, the gaseous-phase amine is HDA, and the molar ratio of HDA to phosgene is between 1:2 and 8, preferably between 1:3 and 5. The feeding temperature: the feeding temperature of HDA is between 220 - 380 °C, preferably between 260 - 320 °C; the feeding temperature of phosgene is equal to or slightly higher than the feeding temperature of HDA, preferably 10 - 50 °C higher than the feeding temperature of HDA, most preferably 10 - 30 °C. The reaction temperature: the reaction temperature is controlled to be not higher than the feeding temperature of phosgene by 10 - 30 °C. The feeding pressure: the pressure of phosgene is 0 - 1.0 MPa, preferably 0.1 - 0.5 MPa, most preferably 0.2 - 0.3 MPa; the pressure of HDA is preferably 0.1 - 0.5 MPa, most preferably 0.2 - 0.3 MPa.

[0032] In this article, the orientation words "front" and "rear" are defined according to the flow direction of the fluid in the reactor body, with the downstream end of the fluid being the front and the upstream end being the rear.

[0033] The present invention adopts the above - mentioned solution and has the following advantages compared with the prior art:

[0034] For the gas - phase phosgenation reactor of the present invention, two raw materials for the gas - phase phosgenation reaction are fed through the main channel and the side channel of the feeding unit and then impact and mix in the first reaction channel. After the material is split through the split - flow channel of the mixing unit, it further impacts and mixes in the second reaction channel, strengthening the mixing effect. Then, after being split, collected and discharged through the discharging unit, while ensuring a good mixing effect, the generation of by - products is reduced or avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 FIG. is a schematic diagram of a gas - phase phosgenation reactor according to an embodiment of the present invention.

[0037] Figure 2 FIG. is a three - dimensional schematic diagram of the first reactor body according to an embodiment of the present invention.

[0038] Figure 3 is Figure 2 a cross - sectional view of the first reactor body shown along its length direction.

[0039] Figure 4 FIG. is a schematic diagram of the first feed port and the second feed port of the reactor body according to an embodiment of the present invention.

[0040] Figure 5 FIG. is a three - dimensional schematic diagram of the second reactor body according to an embodiment of the present invention.

[0041] Figure 6 FIG. is a three - dimensional schematic diagram of the third reactor body according to an embodiment of the present invention.

[0042] Among them,

[0043] 100 - reactor body; 100a - straight pipe; 100b - elbow pipe; 100c - inner pipe; 101a, 101b, 101c - inlet section; 102a, 102b, 102c - arc section; 103a, 103b, 103c - outlet section; 104 - first feed port; 105 - second feed port; 200 - housing; 201 - discharge port;

[0044] 1 - feeding unit; 11 - first main channel; 12 - first side channel;

[0045] 2 - First connection unit; 21 - First reaction channel;

[0046] 3 - Mixing unit; 31 - Shunt channel;

[0047] 4 - Second connection unit; 41 - Second reaction channel;

[0048] 5 - Discharge unit; 51 - Second main channel; 52 - Second side channel;

[0049] 6 - Third connection unit; 61 - Third reaction channel. Detailed implementation mode

[0050] The following elaborates on the preferred embodiments of the present invention in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted here that the description of these embodiments is for helping to understand the present invention, but does not constitute a limitation to the present invention.

[0051] It should be noted that the orientation terms "front" and "rear" mentioned in the claims and the specification are defined according to the flow direction of the fluid in the reactor, with the downstream end of the fluid being the front and the upstream end being the rear; specifically as Figure 3 shown, "front" corresponds to Figure 3 the lower side of the paper surface, and "rear" corresponds to Figure 3 the upper side of the paper surface.

[0052] Referring to Figure 1 shown, the gas-phase phosgenation reactor of this embodiment includes a housing 200 and a reactor main body 100 disposed in the housing 200. The housing 200 is internally provided with a cooling medium, and most of the reactor main body 100 is immersed in the cooling medium. The housing 200 also has a discharge port 201, and the outlet of the reactor main body 100 is directly or through a discharge pipe and this discharge port 201 is communicated. This cooling medium is selected as a liquid-phase inert solvent, which can be selected from toluene, xylene, chlorobenzene, and ortho-dichlorobenzene. After contacting with the reactor main body 100, it heats up or vaporizes to take away the reaction heat. The inside of the housing 200 maintains a positive pressure, and the temperature of the cooling medium in the housing 200 is controlled to be 5 - 30 °C lower than the reaction temperature.

[0053] A reactor main body 100 of this embodiment is as Figures 2 to 4As shown, the reactor body 100 includes a feeding unit 1, a first connection unit 2, a plurality of mixing units 3, a second connection unit 4 and a discharging unit 5. The feeding unit 1, the first connection unit 2, the mixing units 3, the second connection unit 4 and the discharging unit 5 are connected in sequence from the rear to the front. The reactor body 100 is formed by cross-connecting a plurality of pipes (including straight pipes 100a and bent pipes 100b), and the fluid flow passage of the reactor body 100 is formed by the lumen of the pipes. In some other embodiments, the reactor body 100 is formed by a substrate with chambers opened, and the fluid flow passage of the reactor body 100 is the chamber opened in the substrate.

[0054] Combined Figure 3 with Figure 4 As shown, the reactor body 100 has a first feed inlet 104 and a second feed inlet 105, and the first feed inlet 104 and the second feed inlet 105 are used to introduce two reaction raw materials for the gas-phase phosgenation reaction respectively. Specifically, the second feed inlet 105 is annular and surrounds the first feed inlet 104. The second feed inlet 105 is used to introduce phosgene, and the first feed inlet 104 is used to introduce another raw material for the gas-phase phosgenation reaction, such as a gas-phase amine. In this embodiment, a thinner inner pipe 100c is inserted into the rear part of the first straight pipe 100a ( Figure 3 the uppermost straight pipe 100a). The rear end of the lumen of the inner pipe 100c is the first feed inlet 104, and it extends downward to the front end of the feeding unit 1; an annular channel is formed between the first straight pipe 100a and the inner pipe 100c, and the rear end of this channel is the second feed inlet 105. The inner pipe 100c is fixed in the first straight pipe 100a. If the feed pipe connected to the inner pipe 100c is fixed, or fixed to the first straight pipe 100a through a baffle, the baffle is provided with through holes allowing the gas-phase raw materials to enter.

[0055] The feeding unit 1 has a first main channel 11 and a plurality of first side channels 12, and the plurality of first side channels 12 are arranged beside the first main channel 11. The first main channel 11 extends linearly along the length direction (i.e., the front-rear direction) of the reactor body 100, and the first side channels 12 are configured to have a bent shape that can prevent the fluid from flowing from its outlet to the inlet; the number of the first side channels 12 is 2 to 6, and they are evenly spaced along the circumferential direction of the first main channel 11. In this embodiment, the number of the first side channels 12 is 2, and they are respectively arranged on the opposite sides of the first main channel 11. The inlet of the first main channel 11 is communicated with the above-mentioned first feed inlet 104, the inlets of the respective first side channels 12 are communicated with the above-mentioned second feed inlet 105, and the outlet of the first main channel 11 and the outlets of the plurality of first side channels 12 converge. Further, the feeding unit 1 is mainly composed of the first straight pipe 100a ( Figure 3The first positive Tesla valve structure is formed by the intersection of the uppermost straight pipe 100a) and multiple bent pipes 100b. The lumen of the inner pipe 100c within the straight pipe 100a is the aforementioned first main channel 11, and the lumen of the bent pipe 100b and the annular cavity between the straight pipe 100a and the inner pipe 100c form the aforementioned first side channel 12.

[0056] In this embodiment, the front end of the inner pipe 100c and the first straight pipe 100a are not sealed. In some other embodiments, the front end of the inner pipe 100c and the straight pipe 100a are sealed. Then, the first main channel 11 includes the lumen of the inner pipe 100c and a part of the lumen of the first straight pipe 100a. In still some other embodiments, the inner pipe 100c is not provided within the first straight pipe 100a. The first feed port 104 is formed by the rear end of the first straight pipe 100a, and the second feed port 105 is opened on the bent pipe 100b. At this time, the first main channel 11 is the lumen at the rear of the first straight pipe 100a, and the first side channel 12 is the lumen of the bent pipe 100b.

[0057] The first connection unit 2 has a first reaction channel 21 that extends in the front-rear direction, and its rear end communicates with the confluence of the outlet of the first main channel 11 and the outlet of the first side channel 12. Further, the first connection unit 2 is formed by the lumen of the front part of the first straight pipe 100a, and the rear end of the first reaction channel 21 is connected to the outlet of the aforementioned first positive Tesla valve structure.

[0058] The mixing unit 3 has multiple diversion channels 31. The inlets of the respective diversion channels 31 communicate with the front end of the first reaction channel 21, and the outlets of the respective diversion channels 31 converge. The diversion channels 31 are bent outward. Here, the orientation terms "inner" and "outer" are defined with reference to the center line of the first reaction channel 21. Away from the center line is considered outer, and vice versa is inner. The number of diversion channels 31 is 2 to 6 and is evenly spaced along a circumferential direction. In this embodiment, the number of the first side channels 12 is 2. Specifically, each of the diversion channels 31 is formed by the bent pipe 100b, and multiple bent pipes 100b intersect to form a reverse Tesla valve structure. The number of mixing units 3 is preferably 2 to 5. Specifically, the number of mixing units 3 is 3. Every two mixing units 3 are connected by a third connection unit 6 having a third reaction channel 61. The first reaction channel 21 and the second reaction channel 41 of the second connection unit 4 are connected through the diversion channels 31 and the third reaction channel 61. Each third connection unit 6 is respectively a straight pipe 100a, specifically Figures 1 to 3 the second and third straight pipes among them. The lumen of this straight pipe is the third reaction channel 61.

[0059] The second connection unit 4 has the above-mentioned second reaction channel 41 which extends in the front-rear direction, and the rear end thereof communicates with the confluence of the outlets of the respective diversion channels 31. Further, in combination with Figure 1 and Figure 2 as shown, the second connection unit 4 is formed by the lumen at the rear of a straight pipe 100a (which is the fourth straight pipe, specifically the Figure 2 lower straight pipe 100a), and the rear end of this straight pipe 100a is connected to the outlet of the above-mentioned reverse Tesla valve structure. The first connection unit 2 and the second connection unit 4 are connected through the above-mentioned mixing unit 3, and the first reaction channel 21 and the second reaction channel 41 are only communicated through the above-mentioned two diversion channels 31.

[0060] The discharging unit 5 has a second main channel 51 and a plurality of second side channels 52, and the plurality of second side channels 52 are arranged beside the second main channel 51. The second main channel 51 extends linearly in the length direction (i.e., the front-rear direction) of the reactor body 100, and the second side channels 52 are configured to have a bent shape that can prevent the fluid from flowing from its outlet to its inlet; the number of the second side channels 52 is 2 to 6, and they are evenly spaced along the circumferential direction of the second main channel 51. In this embodiment, the number of the second side channels 52 is 2, and they are respectively arranged on the opposite sides of the second main channel 51. The second side channels 52 are configured to have a bent shape that can prevent the fluid from flowing from its outlet to its inlet, the inlet of the second main channel 51 and the inlets of the second side channels 52 communicate with the second reaction channel 41, and the outlet of the second main channel 51 and the outlets of the plurality of second side channels 52 converge. Further, the discharging unit 5 is a second forward Tesla valve structure formed by the intersection of a straight pipe 100a (specifically the above-mentioned fourth straight pipe) and a plurality of bent pipes 100b. The lumen at the front of the fourth straight pipe 100a is the above-mentioned second main channel 51, and the lumen of the bent pipe 100b is the above-mentioned second side channel 52. Further, in this embodiment, the structures of the feeding unit 1 and the discharging unit 5 are generally similar, the difference being that: in the feeding unit 1, the inlet of the first main channel 11 and the inlet of the first side channel 12 are not communicated; the first main channel 11 is formed by an inner pipe 100c, while the second main channel 51 is formed by the lumen at the front of the fourth straight pipe 100a.

[0061] As Figure 3As shown, the curved portions of the first side channels 12 respectively include an inlet section 101a extending obliquely outward from its inlet, and an outlet section 103a extending obliquely outward from its outlet. The inlet section 101a and the outlet section 103a are connected by an arc section 102a; the diversion channel 31 includes an inlet section 101b extending obliquely outward from its inlet, and an outlet section 103b extending obliquely outward from its outlet. The inlet section 101b and the outlet section 103b are connected by an arc section 102b; the curved portion of the second side channel 52 includes an inlet section 101c extending obliquely outward from its inlet, and an outlet section 103c extending obliquely outward from its outlet. The inlet section 101c and the outlet section 103c are connected by an arc section 102c. The inlet section 101a of the first side channel 12 gradually inclines backward and outward from its inlet, and the outlet section 103a of the first side channel 12 gradually inclines backward and outward from its outlet; the inlet section 101b of the diversion channel 31 gradually inclines forward and outward from its inlet, and the outlet section 103b of the diversion channel 31 gradually inclines forward and outward from its outlet; the inlet section 101c of the second side channel 52 gradually inclines backward and outward from its inlet, and the outlet section 103c of the second side channel 52 gradually inclines backward and outward from its outlet. The arc section 102a of the first side channel 12 is located at the rear side of its inlet section 101a and outlet section 103a, the arc section 102b of the diversion channel 31 is located at the front side of its inlet section 101b and outlet section 103b, and the arc section 102c of the second side channel 52 is located at the rear side of its inlet section 101c and outlet section 103c. Further, the shape of the curved portion of the first side channel 12 is the same as the shape of the curved portion of the second side channel 52, and the shape of the diversion channel 31 is mirror-symmetrical with respect to a horizontal plane to the shape of the curved portion of the first side channel 12 / the second side channel 52.

[0062] The first main channel 11, the first reaction channel 21, the second main channel 51, and the second reaction channel 41 respectively extend along the length direction of the reactor main body 100 and are aligned. The included angle between the extending direction of the inlet section 101 and the length direction of the reactor main body 100 is less than 90 degrees, and the included angle between the extending direction of the outlet section 103 and the length direction of the reactor main body 100 is less than 90 degrees, preferably both are 45 degrees. The ratio of the inner arc radius to the outer arc radius of the inner edges of the arc sections 102a, 102b, 102c is 1:2 - 6, preferably 1:4.

[0063] The first reaction channel 21, the second reaction channel 41, the third reaction channel 61, the first main channel 11, the first side channel 12, the shunt channel 31, the second main channel 51, and the second side channel 52 are all formed by pipes. The pipes include a plurality of straight pipes 100a and a plurality of bent pipes 100b. The bent pipes 100b are arranged at intervals and staggered around the straight pipes 100a. These bent pipes 100b and the straight pipes 100a are cross-connected to form the above-mentioned reactor body 100. Among them, the first main channel 11, the first reaction channel 21, the second reaction channel 41, the third reaction channel 61, and the second main channel 51 are aligned in the front-rear direction.

[0064] Another reactor body 100 of the present embodiment is as Figure 5 shown, and its difference from the reactor body 100 shown in Figure 2 is that the number of mixing units 3 is one, and the first connection unit 2 and the second connection unit 4 are communicated through two shunt channels 31 of one mixing unit 3.

[0065] Another reactor body 100 of the present embodiment is as Figure 6 shown, and its difference from the reactor body 100 shown in Figure 2 is that: (1) the number of mixing units 3 is three, and every two mixing units 3 are connected by a third connection unit 6 having a third reaction channel 61. The first reaction channel 21 and the second reaction channel 41 are communicated through the shunt channel 31 and the third reaction channel 61; (2) the number of the first side channels 12, the shunt channels 31, and the second side channels 52 are three respectively, and they are evenly arranged at intervals along the circumferential direction.

[0066] The present embodiment also provides the application of the above-mentioned gas-phase phosgenation reactor in the preparation of isocyanates. In the method for preparing isocyanates, the above-mentioned gas-phase phosgenation reactor is used. The gaseous amine is introduced into the first main channel 11 through the first feed port 104, and the phosgene is introduced into a plurality of first side channels 12 through the second feed port 105. After the gaseous amine and the phosgene enter the first reaction channel 21 for preliminary reaction, they are further mixed and reacted in the second reaction channel 41 after being shunted through a plurality of shunt channels 31, and then are shunted and collected through the second main channel 51 and a plurality of second side channels 52 and then discharged; a quenching agent is used to quench the reactants discharged from the discharging unit 5 to remove phosgene to obtain the target product. At the same time, a cooling medium is provided inside the housing 200, the reactor body 100 is arranged inside the housing 200, and the temperature of the cooling medium inside the housing 200 is controlled to be 5 - 30 °C lower than the reaction temperature of the gaseous amine and the phosgene. The cooling medium is a liquid-phase inert solvent, and a positive pressure is maintained inside the housing 200. The liquid-phase inert solvent vaporizes or heats up to take away the heat of the reactor body 100.

[0067] The gaseous-phase amine specifically uses HDA, and the process parameters are as follows:

[0068] 1. The molar ratio of HDA to phosgene: between 1:2 and 8, preferably between 1:3 and 5;

[0069] 2. The temperature of the feed: The feed temperature of HDA is between 220 and 380 °C, preferably between 260 and 320 °C; the feed temperature of phosgene is between 220 and 380 °C, preferably between 260 and 320 °C.

[0070] 3. The temperature of the reaction: The reaction temperature is controlled to be 10 to 30 °C lower than the feed temperature.

[0071] 4. The pressure of the feed: The pressure of phosgene is 0 to 1.0 MPa, preferably 0.1 to 0.5 MPa, and most preferably 0.2 to 0.3 MPa; the pressure of HDA is preferably 0.1 to 0.5 MPa, and most preferably 0.2 to 0.3 MPa.

[0072] 5. The liquid-phase inert solvent in the shell 200: The temperature of the liquid-phase inert solvent in the shell 200 is controlled to be about 5 to 30 °C lower than the reaction temperature, preferably 10 to 20 °C lower than the reaction temperature; the pressure of the shell 200 is controlled to be the saturated vapor pressure of the solvent temperature in the shell 200 to remove the reaction heat by means of the evaporation of the solvent.

[0073] Specific examples are provided below.

[0074] Example 1

[0075] The gas-phase phosgenation reactor uses Figure 6 the reactor main body 100 shown in the figure. Three mixing units 3 are connected between the feed unit 1 and the discharge unit 5, that is, two forward Tesla valve structures and three reverse Tesla valve structures are used, and the branches (side channels or shunt channels 31) of adjacent Tesla valve structures are arranged out of phase in the circumferential direction. The number of the first side channels 12 / second side channels 52 / shunt channels 31 is 3 respectively, and the angle with the length direction of the reactor main body 100 is 45 degrees. The ratio of the inner arc radius to the outer arc radius of the inner edge of each arc segment 102 is 1:4. The temperature of the solvent in the shell 200 is controlled to be 15 °C lower than the reaction temperature. The temperature of the liquid-phase inert solvent is 285 °C, and chlorobenzene solvent is used, and the reaction temperature is controlled to be 300 °C.

[0076] HDA is heated and vaporized to 280 °C, and phosgene is heated and vaporized to 280 °C. HDA is introduced through the first feed port 104, and phosgene is introduced through the annular second feed port 105. The feed molar ratio of HDA to phosgene is 1:4. The HDA material flows forward through the first main channel 11 of the feed unit 1. At the outlet, it is mixed with phosgene in a plurality of curved first side channels 12, passes through the first reaction channel 21, and then sequentially passes through a plurality of mixing units 3. The mixing is enhanced through the plurality of curved diversion channels 31 of each mixing unit 3. The reactants are discharged from the outlet of the discharge unit 5 and enter the quenching zone. The solvent chlorobenzene (MCB) quenches the high-temperature reactants to 130 °C. After the gas-phase components are treated by the phosgene absorption tower and the phosgene stripping tower, the excess phosgene is recovered and reused. The liquid-phase crude product is stripped of a small amount of phosgene, solvent, front-end impurities, and heavy components, etc. to obtain the target product HDI. The yield of the product is calculated to be 98.6% (based on amine).

[0077] In this embodiment, the feed unit with a forward Tesla valve structure feeds the gas-phase amine and phosgene separately and effectively avoids backmixing; the mixing unit with a reverse Tesla valve structure increases the mixing and impact between materials by diversion and then collection (the collection area is small); the discharge unit with a forward Tesla valve structure diverts and then collects the materials to increase the discharge flow rate and avoid backmixing; through the combination of these units, on the premise of ensuring a good mixing effect, the problem of easy blockage is solved, and at the same time, by-products caused by backmixing are prevented. The gas-phase amine material flows forward through the first main channel of a forward Tesla valve structure, and at the outlet, it is mixed with phosgene transported by a plurality of curved first side channels of this forward Tesla valve structure. After passing through a section of pipeline, it is further mixed by a reverse Tesla valve structure, and then discharged at a high speed through a forward Tesla valve unit, ensuring a good mixing effect while avoiding the generation of by-products.

[0078] Furthermore, the entire reaction system is placed in a closed shell filled with a liquid-phase inert solvent. The shell maintains a positive pressure, such that the saturation temperature of the liquid in the shell is slightly lower than the target reaction temperature by 10 - 20 °C. The reaction heat is carried away by the vaporization or temperature rise of the liquid-phase inert solvent in the shell to avoid too high a rise in the reaction temperature. Since the gas-phase phosgene reaction itself releases a large amount of reaction heat, this embodiment also avoids reducing the temperature of the reactants by quenching the gas-phase phosgenation reaction mixture with a solvent, thus avoiding the problem of waste of the valuable high-temperature energy generated by the reaction.

[0079] The gas-phase phosgenation reactor of this embodiment is a preparation device that can efficiently and rapidly mix reactants, effectively utilize the large amount of reaction heat released by the reaction, reduce the reaction temperature of the system, and reduce the generation of side reactions.

[0080] Example 2

[0081] Example 2 uses the same gas-phase reactor as Example 1, except that the temperature of the liquid-phase inert solvent is 270 °C, chlorobenzene solvent is used, the reaction temperature is controlled at 290 °C, and the yield of the product is calculated to be 97.2% (based on amine).

[0082] Example 3

[0083] Example 3 uses the same gas-phase phosgenation reactor as Example 1, except that the temperature of the liquid-phase inert solvent is 300 °C, chlorobenzene solvent is used, the reaction temperature is controlled at 310 °C, and the yield of the product is calculated to be 97.5% (based on amine).

[0084] Example 4

[0085] The difference between this example and Example 1 lies in the different gas-phase phosgenation reactors. The reactor shown in Figure 1 is used. There are 3 mixing units 3 connected between the feeding unit 1 and the discharging unit 5, that is, 2 forward Tesla valve structures and 3 reverse Tesla valve structures are used. The branches (side channels or shunt channels 31) of adjacent Tesla valve structures are arranged in a circumferential dislocation. The number of the first side channels 12 / the second side channels 52 / the shunt channels 31 are 2 respectively.

[0086] HDA is heated and vaporized to 280 °C, phosgene is heated and vaporized to 280 °C. HDA is introduced from the first feeding port 104, phosgene is introduced from the annular second feeding port 105. The feeding molar ratio of HDA and phosgene is 1:4. The HDA material flows forward through the first main channel 11 of the feeding unit 1, and is mixed with phosgene in the first side channels 12 at the outlet. After passing through the first reaction channel 21, it then passes through multiple mixing units 3 in sequence. The mixing is strengthened through the multiple curved shunt channels 31 of each mixing unit 3. The reactants are discharged from the outlet of the discharging unit 5 and enter the quenching zone. The solvent chlorobenzene (MCB) quenches the high-temperature reactants to 130 °C. The gas-phase components are processed through a phosgene absorption tower and a phosgene stripping tower to recover the excess phosgene and reuse it. The liquid-phase crude product is removed of a small amount of phosgene, solvent, front impurities, and heavy components, etc. to obtain the target product HDI. The yield of the product is calculated to be 96.9% (based on amine).

[0087] Example 5

[0088] The difference between this example and Example 1 lies in the different gas-phase phosgenation reactors. The gas-phase phosgenation reactor uses the reactor body 100 shown in Figure 5 There is 1 mixing unit 3 connected between the feeding unit 1 and the discharging unit 5, that is, 2 forward Tesla valve structures and 1 reverse Tesla valve structure are used. The branches (side channels or shunt channels 31) of adjacent Tesla valve structures are arranged in a circumferential dislocation. The number of the first side channels 12 / the second side channels 52 / the shunt channels 31 are 2 respectively.

[0089] The HDA is heated and vaporized to 280 °C, and the phosgene is heated and vaporized to 280 °C. The HDA is introduced through the first feed port 104, and the phosgene is introduced through the annular second feed port 105. The feed molar ratio of HDA to phosgene is 1:4. The HDA material flows forward through the first main channel 11 of the feed unit 1. At the outlet, it is mixed with the phosgene in the multiple curved first side channels 12. After passing through the first reaction channel 21, it then passes through 1 mixing unit 3 in sequence. The mixing is strengthened through the curved shunt channels 31 of each mixing unit 3. The reactants are discharged from the outlet of the discharge unit 5 and enter the quenching zone. The solvent chlorobenzene (MCB) quenches the high-temperature reactants to 130 °C. The gas-phase components are treated by a phosgene absorption tower and a phosgene stripping tower, and the excess phosgene is recovered and reused. The liquid-phase crude product is removed of a small amount of phosgene, solvent, front impurities, and heavy components, etc. to obtain the target product HDI. The yield of the product is calculated to be 96.3% (based on amine).

[0090] Example 6

[0091] This example uses the same gas-phase phosgenation reactor as in Example 1. The IPDA is heated and vaporized to 320 °C, and the phosgene is heated and vaporized to 320 °C. The IPDA is introduced through the first feed port 104, and the phosgene is introduced through the annular second feed port 105. The feed molar ratio of IPDA to phosgene is 1:4. The IPDA material flows forward through the first main channel 11 of the feed unit 1. At the outlet, it is mixed with the phosgene in the multiple curved first side channels 12. After passing through the first reaction channel 21, it then passes through multiple mixing units 3 in sequence. The mixing is strengthened through the multiple curved shunt channels 31 of each mixing unit 3. The reactants are discharged from the outlet of the discharge unit 5 and enter the quenching zone. The solvent chlorobenzene (MCB) quenches the high-temperature reactants to 130 °C. The gas-phase components are treated by a phosgene absorption tower and a phosgene stripping tower, and the excess phosgene is recovered and reused. The liquid-phase crude product is removed of a small amount of phosgene, solvent, front impurities, and heavy components, etc. to obtain the target product IPDI. The yield of the product is calculated to be 98.5% (based on amine).

[0092] The above examples are only to illustrate the technical concept and characteristics of the present invention. They are a preferred embodiment, and their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A gas-phase phosgenation reactor, comprising a housing capable of containing a cooling medium and a reactor main body disposed within the housing, characterized in that, the reactor main body includes a feed unit, a first connection unit having a first reaction channel, one or more mixing units, a second connection unit having a second reaction channel, and a discharge unit, which are sequentially arranged from the rear to the front; the feed unit has a first main channel and a plurality of first side channels. The plurality of first side channels are disposed beside the first main channel. The whole or at least part of each first side channel is configured to have a bent shape capable of preventing fluid from flowing from its outlet to its inlet. The inlet of the first main channel communicates with a first feed port, and the inlet of the first side channel communicates with a second feed port. The first feed port and the second feed port are used to introduce two reaction raw materials for the gas-phase phosgenation reaction respectively. The outlet of the first main channel and the outlets of the plurality of first side channels converge and communicate with the first reaction channel of the first connection unit; the mixing unit has a plurality of shunt channels. The inlet of each shunt channel communicates with the first reaction channel, and the outlets of the plurality of shunt channels converge and communicate with the second reaction channel of the second connection unit; the discharge unit has a second main channel and a plurality of second side channels. The plurality of second side channels are disposed beside the second main channel. The second side channel is configured to have a bent shape capable of preventing fluid from flowing from its outlet to its inlet. The inlet of the second main channel and the inlets of the plurality of second side channels communicate with the second reaction channel, and the outlet of the second main channel and the outlets of the plurality of second side channels converge; the first side channel, the shunt channel and the second side channel respectively include an inlet section extending obliquely outward from their respective inlets and an outlet section extending obliquely outward from their respective outlets. The inlet section and the outlet section are connected by an arc section. The inlet section of the first side channel gradually inclines backward and outward from its inlet, and the outlet section of the first side channel gradually inclines backward and outward from its outlet. The inlet section of the shunt channel gradually inclines forward and outward from its inlet, and the outlet section of the shunt channel gradually inclines forward and outward from its outlet. The inlet section of the second side channel gradually inclines backward and outward from its inlet, and the outlet section of the second side channel gradually inclines backward and outward from its outlet.

2. The gas-phase phosgenation reactor according to claim 1, characterized in that, the second feed port is annular and surrounds the first feed port, and the second feed port is used to introduce phosgene.

3. The gas-phase phosgenation reactor according to claim 1, characterized in that, the arc section of the first side channel is located at the rear side of its inlet section and outlet section, the arc section of the shunt channel is located at the front side of its inlet section and outlet section, and the arc section of the second side channel is located at the rear side of its inlet section and outlet section.

4. The gas-phase phosgenation reactor according to claim 3, characterized in that, The included angle between the extending direction of the inlet section or the extending direction of the outlet section and the length direction of the reactor body is less than 90 degrees, and the first main channel, the first reaction channel, the second main channel, and the second reaction channel respectively extend along the length direction of the reactor body and are aligned.

5. The gas-phase phosgenation reactor according to claim 4, characterized in that the included angle is between 30 degrees and 60 degrees, the number of the first side channels, the shunt channels, and the second side channels is 2 to 6 and they are arranged at intervals along the circumferential direction of the reactor body, and the ratio of the circular arc radius of the inner edge to the circular arc radius of the outer edge of each arc segment is 1:2 to 6.

6. The gas-phase phosgenation reactor according to claim 1, characterized in that the number of the mixing units is one, and the first reaction channel and the second reaction channel are only connected by a plurality of the shunt channels; or, the number of the mixing units is 2 to 5, and two adjacent mixing units are connected by a third connecting unit having a third reaction channel, and the first reaction channel and the second reaction channel are connected through the shunt channels and the third reaction channel.

7. The gas-phase phosgenation reactor according to claim 1, characterized in that the reactor body is formed by a plurality of pipes, the plurality of pipes include at least two straight pipes and a plurality of bent pipes, wherein the rear part of the first straight pipe is inserted with an inner pipe, at least a part of the first main channel is the lumen of the inner pipe, the first side channels include the lumen of the bent pipes and the cavity between the first straight pipe and the inner pipe, the first reaction channel is formed in the front part of the first straight pipe, the first feed port is formed in the rear end part of the inner pipe, and the second feed port is formed between the rear end part of the inner pipe and the rear end part of the first straight pipe; the second reaction channel and the second main channel are formed in another straight pipe, and the shunt channels and the second side channels are respectively formed by the bent pipes.

8. The gas-phase phosgenation reactor according to claim 1, characterized in that there is also a discharge port on the housing, and the outlets of the second main channel and the second side channels converge and are connected to the discharge port.

9. A method for preparing isocyanate, characterized in that using the gas-phase phosgenation reactor according to any one of claims 1 to 8, introducing the gaseous amine into the first main channel through the first feed port, introducing phosgene into a plurality of the first side channels through the second feed port, enabling the gaseous amine and phosgene to enter the first reaction channel for preliminary reaction, then being shunted through a plurality of the shunt channels and further mixed and reacted in the second reaction channel, and then discharged after being shunted and converged through the second main channel and a plurality of the second side channels.

10. The method for preparing isocyanate according to claim 9, characterized in that a cooling medium is introduced into the housing, the reactor body is arranged in the housing, and the temperature of the cooling medium in the housing is controlled to be 5 to 30 °C lower than the reaction temperature of the gaseous amine and phosgene.

11. The method for preparing isocyanate according to claim 10, It is characterized in that the cooling medium is a liquid-phase inert solvent, a positive pressure is maintained inside the shell, and the heat of the reactor body is taken away after the liquid-phase inert solvent vaporizes or heats up.

12. The method for preparing isocyanate according to claim 9, It is characterized in that a quenching agent is used to quench the reactants discharged from the discharging unit, phosgene is removed, and the target product is obtained.

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