TWI803448B - Reactor and method for producing acrylonitrile - Google Patents

Abstract

The present invention relates to a reactor and process for the production of acrylonitrile. The device includes a reactor main body, a feed distributor horizontally arranged in the reactor main body, the feed distributor includes a pipe group composed of a main pipe and a plurality of branch pipes in fluid communication with the main pipe, the inlet of the main pipe is connected with the The raw material gas source outside the main body of the reactor is connected and the end is closed, and the end of the branch pipe is closed, and a plurality of air outlets are arranged on the main pipe and the branch pipe. When using the reactor according to the present invention, the raw material gas can be evenly distributed in the reactor, thereby helping to improve the production efficiency of acrylonitrile.

Description

Reactor and method for producing acrylonitrile Cross References to Related Applications

This application claims the rights to the Chinese patent application CN201510552970.7 filed on September 2, 2015 entitled "Improved Propylene Ammoxidation Process and Its Reactor" and the title of "Feed Distributor" filed on September 6, 2015 "The Chinese patent application CN201510557615.9, the Chinese patent application CN201510557613.X filed on September 6, 2015 titled "Adjusting Device and Method for Reactor Temperature" and the title submitted on January 8, 2016 titled " The priority of the Chinese patent application CN201610011756.5 for Feed Distributor of Fluidized Bed Reactor for Ammination Oxidation Reaction, the entire content of which is incorporated herein by reference.

The invention relates to the field of chemical industry, in particular to a reactor for producing acrylonitrile. The invention also relates to a process for the production of acrylonitrile using such a reactor.

Acrylonitrile is an important chemical raw material, which is widely used in the fields of synthetic fiber, synthetic rubber and synthetic resin.

At present, ammonia, propylene and air are usually mixed in a fluidized bed reactor Propylene ammoxidation is carried out to produce acrylonitrile. Since propylene is a flammable and explosive gas, it is not possible to mix propylene and air and then feed it into the fluidized bed reactor. One feed port is fed, while air is fed from the other feed port of the fluidized bed reactor. This can lead to uneven distribution of feed gas within the fluidized bed reactor, and thus adversely affect the production efficiency of acrylonitrile.

In view of the above problems, the present invention proposes a reactor for producing acrylonitrile. When using the reactor according to the present invention, the raw material gas can be evenly distributed in the reactor, thereby helping to improve the production efficiency of acrylonitrile. The present invention also proposes a method for producing acrylonitrile using the reactor for producing acrylonitrile.

The reactor for producing acrylonitrile according to the first aspect of the present invention comprises: a reactor main body, a feed distributor horizontally arranged in the reactor main body, the feed distributor includes a main pipe and a plurality of branch pipes in fluid communication with the main pipe The composed tube group, the inlet of the main pipe is connected with the raw material gas source arranged outside the reactor main body and the end is closed, the end of the branch pipe is closed, and a plurality of air outlets are arranged on the main pipe and the branch pipe.

According to the reactor of the present invention, the plurality of branch pipes of the feed distributor extend to most of the area in the reactor in the horizontal direction, so that the raw material gas can be transported into the reactor as uniformly as possible through the feed distributor . In this way, it is ensured that the feed gas is evenly distributed in the reactor, which is very helpful to improve the production efficiency of acrylonitrile.

In one embodiment, the plurality of air outlets on the main pipe are configured as follows: along the flow direction of the raw material gas, the diameter of the downstream air outlets is larger than the aperture of the upstream air outlets; and the plurality of air outlets on the branch pipe are configured: The gas flow direction, the aperture of the downstream air outlet is larger than the aperture of the upstream air outlet. In another embodiment, on the main pipe, the diameter of any air outlet hole is greater than or equal to the aperture diameter of the adjacent upstream air outlet hole; and on the branch pipe, the aperture diameter of any air outlet hole is greater than or equal to the aperture diameter of the adjacent upstream air outlet hole. In another embodiment, on the main pipe, a plurality of air outlets form a plurality of different air outlet groups, the apertures of the air outlets in each air outlet group are the same and the apertures of any air outlet group are greater than or equal to the same The aperture of the air outlet of the adjacent upstream air outlet group; and on the branch pipe, multiple air outlets form a plurality of different air outlet groups, and the apertures of the air outlets in each air outlet group are the same and the outlet of any air outlet group The pore diameter of the air hole is greater than or equal to the pore diameter of the air outlet holes of the adjacent upstream air outlet group.

The applicant found that the mass flow rate of the raw material gas coming out of each gas outlet hole can be substantially the same through the arrangement of the hole diameters of the gas outlet holes, which helps the raw material gas to be evenly distributed in the reactor.

In one embodiment, on the main pipe, the ratio of the diameter of any air outlet to the diameter of the adjacent upstream air outlet is between 1 and 1.08, preferably between 1 and 1.06, more preferably between 1 and 1.04 , more preferably between 1 and 1.02, more preferably between 1 and 1.015, more preferably between 1 and 1.01; and on the branch pipe, the ratio of the aperture of any one air outlet to the aperture of the adjacent upstream air outlet Between 1 and 1.08, preferably between 1 and 1.06, more preferably between 1 and 1.04, more preferably between 1 and 1.02, more preferably between 1 and 1.015, more preferably between 1 and 1.01 .

In one embodiment, on the main pipe, the ratio of the hole diameter of any one group of vent holes to the diameter of the vent holes of the adjacent upstream group of vent holes is between 1 and 1.08, preferably between 1 and 1.06, More preferably between 1 and 1.04, more preferably between 1 and 1.02, more preferably between 1 and 1.015, more preferably between 1 and 1.01; The ratio of the hole diameter to the hole diameter of the air outlet holes of the adjacent upstream air outlet group is between 1 and 1.08, preferably between 1 and 1.06, more preferably between 1 and 1.04, more preferably between 1 and 1.02, and more preferably between 1 and 1.02. Preferably between 1 and 1.015, more preferably between 1 and 1.01.

In one embodiment, when the diameter of the reactor is 10 to 15 meters, among all the vent holes, the ratio of the aperture diameter of the largest vent hole to the aperture of the smallest vent hole is between 1.05 and 1.15, preferably 1.08 to 1.12, when the diameter of the reactor was 5 to 10 meters, in all vent holes, the ratio of the aperture of the largest vent hole to the aperture of the smallest vent hole was between 1.02 and 1.13, preferably between 1.05 and Between 1.11.

In one embodiment, on the main pipe, along the flow direction in the main pipe, the distances between adjacent air outlets are equal to each other; and on the branch pipe, along the flow direction in the main pipe, the distances between adjacent air outlets are equal to each other , preferably, the distance between adjacent air outlets on the main pipe is the same as the distance between adjacent air outlets on the branch pipe.

In one embodiment, on the main pipe, one or more air outlet holes are arranged at the same circumferential position; and on the branch pipe, one or more air outlet holes are arranged at the same circumferential position.

In one embodiment, on the main pipe and the branch pipe, on each outlet A straight diversion pipe is installed at the hole, and the axis of the straight diversion pipe is aligned with the center of the air outlet hole. The diversion branch will rectify the turbulent raw material gas flow from the gas outlet into a stable straight flow, which helps to keep the reaction in the reactor stable.

In one embodiment, on the main pipe, two air outlet holes are arranged at the same circumferential position, the included angle between the guide straight pipes corresponding to the two air outlet holes is 30 to 90 degrees, and on the branch pipe , two air outlets are arranged at the same circumferential position, and the included angle between the guide straight pipes corresponding to the two air outlets is 30 to 90 degrees.

In a preferred embodiment, the ends of the straight guide pipes are in the same plane. This can ensure that the raw material gas can be mixed with air evenly as much as possible.

In one embodiment, in the pipe group, a plurality of branch pipes are parallel to each other, and a main pipe is perpendicular to the plurality of branch pipes. In one embodiment, along the axial direction of the main pipe, the vertical distances between adjacent branch pipes are the same. These structures further enable the feed gas to enter various positions of the reactor, thereby helping the feed gas to be evenly distributed in the reactor.

In one embodiment, in the tube stack, the ratio of the length of the branch tubes to the radius of the reactor body is between 0 and 0.8. According to this structure, the branch pipe has an appropriate length, so that the raw material gas stays in the memory of the branch pipe for a short time, avoiding the nitrogenation of the metal making the branch pipe by the ammonia gas in the raw material gas, thereby improving the service life of the feed distributor .

In one embodiment, the feed distributor includes the same plurality of tube groups, each tube group includes a main pipe and a plurality of branch pipes in fluid communication with the main pipe, and the main pipe of each pipe group is independently communicated with the raw gas source. According to this structure, Since the main pipe of each tube group is independently connected with the raw material gas source, it is helpful for the uniform distribution of the raw material gas in the reactor.

In one embodiment, the plurality of tube groups are evenly distributed in the circumferential direction. In another embodiment, the main pipes of the plurality of tube groups are in a first horizontal plane, and the branch tubes of the plurality of tube groups are in a second horizontal plane different from the first horizontal plane.

In one embodiment, in the main body of the reactor, an air distribution plate is provided below the feed distributor, and the air outlets face the air distribution plate. In this way, the raw material gas and air can be evenly distributed in the reactor, which helps to improve the subsequent reaction efficiency.

In one embodiment, a cooling coil is provided above the feed distributor within the reactor body. Since the reaction of producing acrylonitrile from ammonia, propylene and air is an exothermic reaction, a cooling coil is installed in the main body of the reactor to remove the generated heat out of the reactor in time and keep the reaction temperature at a predetermined temperature.

In one embodiment, the cooling coil includes a plurality of long coils and a plurality of short coils, the length of the long coils is greater than the length of the short coils, and any one of the plurality of long coils and the plurality of short coils All are independently communicated with the cold source arranged outside the reactor main body. Long coils contain more cooling water, which will cause a larger temperature drop/rise in the reactor. Shorter coils hold less cooling water, resulting in less temperature drop/rise in the reactor. In this way, the user can set long coils in some areas inside the reactor body and short coils in other areas according to the actual situation, or even stagger long coils and short coils, so that targeted Implement different temperature control strategies for different regions in the reactor body, and then control the temperature in the reactor body with high sensitivity. Spend. In particular, by switching between long and short coils, or using different long and short coils together, you can achieve a smaller temperature control effect than the short coil, which helps to further precisely control The temperature inside the reactor body. In addition, the operator can make each long and/or short coil function independently as desired, which allows very precise control of the reactor temperature and thus maintains the reaction temperature within the reactor body as a whole. At a predetermined temperature, this is very beneficial for improving the reaction efficiency and the production efficiency of acrylonitrile.

In a preferred embodiment, in the reactor main body, short coils and long coils are arranged in the central area of the cross-section of the reactor, and long coils are arranged in other areas of the cross-section of the reactor. Long coils are used for larger temperature adjustments, while short coils are used for finer temperature adjustments. The temperature in the reactor as a whole can be adjusted sensitively by only setting the short coil in the central area of the cross-section of the reactor, which helps to reduce the complexity of the control of the long and short coils.

In one embodiment, any one of the plurality of long coils and the plurality of short coils is composed of one or more U-shaped tubes connected in series, and in terms of the number of U-shaped tubes, the number of U-shaped tubes of the long coiled tubes The number of U-shaped tubes for short coils is 1 to 3.

In one embodiment, at least one of the long and short coils has an odd number of U-shaped tubes, and at least the other has an even number of U-shaped tubes. Applicants have found that a U-shaped tube produces the smallest magnitude of temperature variation within the reactor. Therefore, by combining these long coils and short coils, it is possible to generate a temperature change in the reactor caused by a U-shaped tube, which helps to accurately control the temperature in the reactor.

A second aspect of the present invention proposes a method for producing acrylonitrile method using the reactor described above. In the main body of the reactor, an air distribution plate is also arranged below the feed distributor, and the air outlet faces the air distribution plate. The method includes: feeding raw material gas into the reactor through a feed distributor, and feeding air into the reactor through an air distribution plate, so that the raw material gas and air react in the reactor under the action of a catalyst to form a The product of acrylonitrile, the product containing acrylonitrile is purified to obtain acrylonitrile.

According to the above, the feed distributor can deliver the raw material gas into the reactor as evenly as possible, and the feed distributor and air distribution plate are set to make the raw material gas and air evenly distributed in the reactor, which helps Improve the production efficiency of acrylonitrile.

In one embodiment, in the reactor, the reaction pressure is 0.04-0.05 MPa in gauge pressure, and the operating linear velocity V is 0.7-1.0 m/s. The catalyst is a Mo-Bi series acrylonitrile catalyst with an average particle diameter of 40-80 μm. The reaction temperature is 420-460°C, the feed gas is a mixture of propylene and ammonia, and the molar ratio of propylene, ammonia and air is 1:(1.1-1.3):(9-10.5). Under such reaction conditions and catalyst, propylene, ammonia and air can fully react to produce acrylonitrile. Compared with the operating linear velocity V of 0.5-0.68m/s in the prior art, the method of the present invention greatly increases the operating linear velocity, thereby greatly improving the production efficiency of acrylonitrile. Mo-Bi series acrylonitrile catalysts are commonly used catalysts in this field, and will not be repeated here.

In one embodiment, the fineness distribution of the catalyst is as follows. In terms of weight content, particles with a particle diameter greater than 90 microns account for 0-30%, particles with a particle diameter between 45 microns and 90 microns account for 20-70%, and particles with a particle diameter of 45 microns to 90 microns account for 20-70%. The particle size is less than 45 microns accounted for 30-50%, of which the particle size is less than 20 μm less than 10%. The applicant found that this The finely distributed catalyst has the best catalytic efficiency. What's more, in the method of the present invention, at such a large operating linear velocity, the run-off rate of the catalyst is equal to or even less than that of the catalyst in the prior art, which is very helpful to the smooth progress of the reaction and reduces the The frequency at which catalyst is replenished to the reactor.

In one embodiment, during the reaction, the fineness distribution of the catalyst in the reactor is analyzed, and the fineness distribution of the catalyst in the reactor is maintained as follows, calculated by weight, the particles with a particle size greater than 90 microns account for 0-30%, particles with a particle size between 45 microns and 90 microns account for 20-70%, and particles smaller than 45 microns account for 30-50%, of which the particle size is less than 20 microns and no more than 10%.

其中，a和b為常數，並且a的取值範圍為2.5-3.5，b的取值範圍為3.5-4.8，冷卻盤管的高度H大於等於催化劑的流化高度h。 In one embodiment, in the reactor, a cooling coil is vertically arranged above the feed distributor, and the fluidization height h of the catalyst and the operating linear velocity V conform to the following relationship:

Wherein, a and b are constants, and the value range of a is 2.5-3.5, the value range of b is 3.5-4.8, and the height H of the cooling coil is greater than or equal to the fluidization height h of the catalyst.

Compared with the prior art, the present invention has the advantage that: the feed distributor can evenly distribute the feed gas in the reactor, thereby helping to improve the production efficiency of acrylonitrile. The setting of the feed distributor and the air distribution plate makes the feed gas and air evenly distributed in the reactor, which also helps to improve the production efficiency of acrylonitrile.

1‧‧‧Feed distributor

2‧‧‧feed pipe

3‧‧‧air tube

4‧‧‧Air distribution plate

5‧‧‧cooling coil

6‧‧‧Separation device

7‧‧‧Raw gas source

8‧‧‧cold source

10‧‧‧reactor

11‧‧‧reactor body

12‧‧‧Head

31, 32, 33‧‧‧sub-coil

101‧‧‧Supervisor

102‧‧‧branch

103‧‧‧air outlet

104‧‧‧Center

105‧‧‧straight diversion pipe

106‧‧‧tube group

111‧‧‧The cross section of the reactor

Hereinafter, the present invention will be described based on the embodiments and with reference to the accompanying drawings for a more detailed description. Wherein: Fig. 1 shows schematically an embodiment of the reactor for producing acrylonitrile according to the present invention; Fig. 2 shows schematically an embodiment of the feed distributor according to the present invention; Fig. 3 shows schematically The sectional view shown in B-B among Fig. 2; Fig. 4 has shown schematically another embodiment of the air outlet of feed distributor and drainage straight pipe; Fig. 5 has shown schematically according to feed distributor of the present invention Another embodiment; Fig. 6 schematically shows another embodiment of the feed distributor according to the present invention; Fig. 7 schematically shows another embodiment of the feed distributor according to the present invention; Fig. 8 schematically Fig. 9 schematically shows a portion of an embodiment of a cooling coil according to the present invention; Fig. 10 schematically shows a cooling coil according to the present invention One embodiment of an arrangement of cooling coils; FIG. 11 schematically shows another embodiment of an arrangement of cooling coils according to the invention; FIG. 12 schematically shows an arrangement of cooling coils according to the invention Another embodiment of the method; and Fig. 13 schematically shows another embodiment of the arrangement of cooling coils according to the present invention.

In the drawings, the same reference numerals are used for the same parts. The drawings are not to scale. In addition, in Figure 2 and Figures 5-8, the symbols "○", "X" and "△" represent air outlets of different diameters.

For the specification, abstract and claims, it should be noted that the singular forms "a", "the", etc. also include the plural unless expressly stated otherwise.

Figure 1 schematically shows a reactor 10 for the production of acrylonitrile according to the invention. As shown in FIG. 1 , the reactor 10 includes a cylindrical reactor body 11 and a semi-ellipsoidal head 12 . A feed distributor 1 and an air distribution plate 4 are arranged horizontally in the reactor main body 11 , preferably, the feed distributor 1 and the air distribution plate 4 are spaced apart and the feed distributor 1 is above the air distribution plate 4 .

The feed pipe 2 for the raw material gas passes through the side wall of the reactor main body 11 and extends to the inside of the reactor 10 , and communicates with the feed distributor 1 . The air pipe 3 also extends into the reactor 10 through the side wall of the reactor main body 11 to distribute the incoming air into the reactor 10 through the air distribution plate 4 . In this way, under the action of the feed distributor 1 and the air distribution plate 4 , the feed gas and air from the feed gas source 7 are uniformly mixed in the reactor 10 . The mixture of feed gas and air then reacts under the action of a catalyst (not shown) in reactor 10 to produce acrylonitrile. It should be noted that raw gas source 7 is not The component part of reactor 10 of invention, in addition, feed pipe 2 and air pipe 3 are separated, and this is because the raw material gas of producing acrylonitrile usually is ammonia and propylene, and propylene, ammonia are flammable and explosive gases, therefore It cannot be mixed with air and fed into the reactor 10.

In addition, a separation device 6 may also be provided in the reactor 10 to separate the produced acrylonitrile from the entrained catalyst particles, so as to facilitate the subsequent further operation of the acrylonitrile and the catalyst. The separation device 6 is usually a cyclone separator, and of course those skilled in the art can also choose other types of separators.

The incoming distributor 1 of the present invention will be described in detail below.

Figure 2 shows an embodiment of a feed distributor. As shown in FIG. 2 , the feed distributor 1 is formed as a pipe group 106 including a main pipe 101 and a plurality of branch pipes 102 in fluid communication with the main pipe 101 . The main pipe 101 communicates with the feed pipe 2, and the ends of the main pipe 101 and the branch pipe 102 are closed. Both the main pipe 101 and the branch pipe 102 are provided with a plurality of air outlet holes 103 . In this way, after the raw material gas enters the feed distributor 1 , the raw material gas can only flow out from the air outlet 103 , so the raw material gas is evenly dispersed into the reactor 10 by the feed distributor 1 .

Preferably, the plurality of outlet holes 103 on the main pipe 101 are configured such that: along the flow direction of the raw material gas, the diameter of the downstream outlet holes is larger than the aperture of the upstream outlet holes; and the plurality of outlet holes 103 on the branch pipe 102 are configured as follows: In the flow direction of raw material gas, the pore diameter of the downstream air outlet is larger than that of the upstream air outlet. In this way, the mass flow rate of the raw material gas coming out of each gas outlet is substantially the same, which helps to further promote the uniform distribution of the raw material gas in the reactor 10 . In an embodiment not shown, on the main pipe 101, multiple air outlet holes form a plurality of different air outlet hole groups. The vent holes 103 in each vent hole group The hole diameters are the same and the hole diameter of any one hole group is greater than or equal to the hole diameter of the adjacent upstream hole group; the same is true on the branch pipe. This also makes it possible to achieve approximately the same mass flow rate of the feed gas coming out of each gas outlet.

Those skilled in the art can set the diameter of each air outlet hole 103 according to the actual situation. In one embodiment, on the main pipe 101, the ratio of the diameter of any air outlet to the diameter of the adjacent upstream air outlet is between 1 and 1.08, preferably between 1 and 1.06, more preferably between 1 and 1.04 Between, more preferably between 1 and 1.02, more preferably between 1 and 1.015, more preferably between 1 and 1.01. On the branch pipe 102, the ratio of the aperture of any air outlet 103 to the aperture of the adjacent upstream air outlet is between 1 and 1.08, preferably between 1 and 1.06, more preferably between 1 and 1.04, more preferably between Between 1 and 1.02, more preferably between 1 and 1.015, more preferably between 1 and 1.01.

In another embodiment, for the air outlet group, on the main pipe 101, the ratio of the diameter of the air outlet of any air outlet group to the aperture of the air outlet of the adjacent upstream air outlet group is between 1 and 1.08 , preferably between 1 and 1.06, more preferably between 1 and 1.04, more preferably between 1 and 1.02, more preferably between 1 and 1.015, more preferably between 1 and 1.01. On the branch pipe 102, the ratio of the aperture diameter of the air outlet of any air outlet group to the aperture of the air outlet of the adjacent upstream air outlet group is between 1 and 1.08, preferably between 1 and 1.06, and more preferably between 1 and 1.06. Between 1.04, more preferably between 1 and 1.02, more preferably between 1 and 1.015, more preferably between 1 and 1.01.

In a specific embodiment, the diameter of the air outlet hole 103 may be between 3mm and 10mm. For example, when the diameter of the reactor 10 is 5-10 meters , the ratio of the aperture diameter of the largest vent hole to the aperture diameter of the smallest vent hole is between 1.02 and 1.13, preferably between 1.05 and 1.11, for example, the aperture can be 4.5mm, 4.8mm, 4.9mm, 6.7mm, 6.8mm and 7.0mm. When the diameter of reactor 10 is at 10-15 meters, the ratio of the aperture of the largest air outlet to the aperture of the smallest air outlet is between 1.05 and 1.15, preferably between 1.08 and 1.12, for example, the aperture can be 5.8mm , 6.1mm, 6.4mm, 6.5mm.

In addition, on the main pipe 101 , along the fluid flow direction, the distances between adjacent air outlets 103 are equal to each other. On the branch pipe 102, the distances between adjacent air outlet holes 103 are equal to each other. The distance between adjacent air outlet holes 103 may be 100-300mm, preferably 125-275mm, more preferably 150-225mm.

On the main pipe 101, one or more air outlet holes 103 may be provided at the same circumferential position. On the branch pipe 102, one or more air outlet holes 103 may also be provided at the same circumferential position. In the embodiment shown in FIG. 4, two air outlet holes 103 are provided at the same circumferential position.

The main pipe 101 can be selected as a straight pipe, and the branch pipe 102 can be a straight pipe or an arc pipe (as shown in FIG. 7 ). The aperture ratio of the main pipe 101 and the branch pipe 102 is preferably 2.0-3.2. The multiple branch pipes 102 are parallel to each other, and the main pipe 101 is perpendicular to the multiple branch pipes 102 . In addition, along the axial direction of the main pipe 101 , the vertical distance L between adjacent branch pipes 102 is the same. These structures all contribute to the uniform distribution of the feed gas in the reactor 10 . Preferably, the vertical distance L between adjacent branch pipes 102 is twice the distance between adjacent air outlets 103 . In one embodiment, the vertical distance L between adjacent branch pipes 102 may be 200-600mm, preferably 260-550mm, more preferably 300-500mm.

As shown in Figures 3 and 4, on the main pipe 101 and the branch pipe 102, in A straight guide pipe 105 is installed at each air outlet 103 . The straight guide pipe 105 can rectify the turbulent raw material gas flow from the air outlet 103 into a stable straight flow, which helps to keep the reaction in the reactor 10 going on stably. Preferably, the ends of the plurality of directing straight pipes 105 are in the same plane. In addition, on the main pipe 101 and the branch pipe 102, two air outlet holes are arranged at the same circumferential position, and the included angle α between the guide straight pipes corresponding to the two air outlet holes is 30 to 90 degrees.

5 to 8 schematically show embodiments of other types of feed distributors 1 . In these embodiments, the feed distributor 1 includes the same plurality of tube banks 106 , for example four tube banks 106 . These tube groups 106 are distributed in the same cross-section of the reactor main body 11 and evenly distributed in the circumferential direction. Each pipe group includes a main pipe 101 and a plurality of branch pipes 102 in fluid communication with the main pipe 101 , and air outlet holes 103 are provided on the main pipe 101 and the branch pipes 102 . The main tube 101 of each tube group is independently communicated with the raw gas source 7 . In this way, the intake conditions of each tube group can be controlled, thereby ensuring that the raw material gas is evenly distributed in the reactor 10 . In each pipe group, the arrangement of the main pipe 101, the branch pipe 102, and the air outlet 103 is exactly the same as that described above, and will not be repeated here.

In the embodiment shown in FIGS. 5 to 8 , the closed ends of the main tubes 101 of the plurality of tube groups 106 converge at the center 104 of the reactor body 11 , and the branch tubes of the plurality of tube groups 102 do not overlap each other in the circumferential direction. For example, the branch pipes 102 of each pipe group in FIG. 5 only exist on one side of the main pipe 101 . In FIG. 6, multiple branch pipes 102 form multiple squares. In Fig. 7, multiple branch pipes 102 enclose multiple concentric circles. In Fig. 8, a plurality of branch pipes 102 intersect each other.

In another embodiment, the main pipes 101 of the plurality of pipe groups 106 may be in a first horizontal plane, while the branch pipes 102 are in a different plane than the first horizontal plane. in the second level. In this way, the straight diversion pipe 105 on the main pipe 101 and the straight diversion pipe 105 on the branch pipe 102 can be avoided from interfering with each other.

In one embodiment, in each tube group, the ratio of the length of the branch tube 102 to the radius of the reactor main body 11 is between 0-0.8. In this way, it is possible to prevent the raw material gas from being stored in the branch pipe 102 for too long, and to prevent the metal making the branch pipe from being nitrided by the ammonia gas in the raw material gas at high temperature, thereby improving the service life of the feed distributor 1 .

In order to remove the heat released by the reaction of ammonia, propylene and air in time, a cooling coil 5 is also arranged in the reactor 10 . As shown in FIG. 1 , the cooling coil 5 is arranged above the feed distributor 1 .

FIG. 9 schematically shows a part of an embodiment of a cooling coil 5 . As shown in FIG. 9 , the cooling coil 5 includes three independent sub-coils 31 , 32 , 33 , and these sub-coils are independently communicated with the cold source 8 arranged outside the reactor main body 11 . Further sub-coils may also be provided within the reactor 10 .

The multiple sub-coils include multiple long coils 31 , 33 and multiple short coils 32 . The length of the long coil is greater than the length of the short coil, so that the long coil has a stronger cooling capacity than the short coil. In this way, the user can set long coils in some areas inside the reactor body 11 and short coils in other areas according to actual conditions, or even arrange long coils and short coils crosswise. In addition, the user can independently operate each of these cooling sub-units as required, thereby controlling the temperature inside the reactor main body with high sensitivity, which is very beneficial for improving the production efficiency of acrylonitrile.

In order to facilitate the manufacture of the long coil and the short coil, both the long coil and the short coil are composed of one or more U-shaped tubes connected in series. Specifications for these U-tubes are complete They are all the same, so based on the number of U-shaped tubes, the number of U-shaped tubes for long coils is 4 to 8, and the number of U-shaped tubes for short coils is 1 to 3. For the sake of simplicity, 1U here means a coil with one U-shaped tube, 2U means a coil with two U-shaped tubes connected in series, and so on. This notation for coil length is used in Figures 10 to 13.

In a preferred embodiment, at least one of the long and short coils has an odd number of U-shaped tubes, and at least the other has an even number of U-shaped tubes. For example, the combination of long coil and short coil can be 6U/4U/1U, 6U/5U/3U, 7U/6U/4U, 8U/6U/5U/2U. In this way, by combining on/off control of these long coils and short coils, it is possible to control the temperature change inside the reactor 10 caused by the coils with an accuracy of 1U, which helps to precisely control the temperature inside the reactor.

Also as shown in Figures 10 to 13, in the reactor main body 11, short coils and long coils are arranged in the central area of the cross-section 111 of the reactor, and long coils are arranged in other areas of the cross-section 111 of the reactor Tube. In this way, the temperature in the reactor 10 can be rapidly raised and lowered through the long coil, while the short coil is used to finely adjust the temperature in the reactor 10 . In particular, it has been surprisingly found that fine adjustment of the temperature in the reactor 10 as a whole can be achieved by arranging only a few short coils in the central region of the cross-section 111 of the reactor. In this application, the central area of the cross-section of the reactor 10 refers to the range from the center of the cross-section of the reactor 10 to 2/3 of the radius; and the edge area of the cross-section of the reactor 10 refers to the part except the central area .

Example 1:

Reactor 10 diameter is 7 meters, adopts the feed distributor shown in Figure 5, the aperture of gas outlet is respectively 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, adopts the cooling coil pipe shown in Figure 10, The cooling coil height is 6.5m.

The molar ratio of propylene, ammonia and air is 1:1.2:9.5, the reaction pressure is 0.04MPa, the reaction temperature is 440°C, and the operating linear velocity V is 0.8m/s. In terms of weight, catalyst particles with a particle size greater than 90 microns accounted for 15%, particles with a particle size between 45 microns and 90 microns accounted for 53%, particles with a particle size of less than 45 microns accounted for 32%, and particles with a particle size of less than 20 microns accounted for 8%. . Entrained catalyst was separated using a cyclone. Table 1 shows the yield of acrylonitrile, CO ₂ and the run off rate of the catalyst.

Example 2:

Reactor 10 has a diameter of 9 meters, adopts the feed distributor shown in Figure 6, and the apertures of the air outlets are respectively 6.5mm, 6.6mm, 6.7mm, 6.8mm, 6.9mm and 7.0mm, and adopts the cooling method shown in Figure 11. Coil, cooling coil height is 7m.

The molar ratio of propylene, ammonia and air is 1:1.1:9.5, the reaction pressure is 0.05MPa, the reaction temperature is 430°C, and the operating linear velocity V is 0.85m/s. By weight, catalyst particles with a particle size greater than 90 microns accounted for 18%, particles with a particle size between 45 microns and 90 microns accounted for 47%, particles with a particle size of less than 45 microns accounted for 35%, and particles with a particle size of less than 20 microns accounted for 8%. . Entrained catalyst particles were separated from the product using a cyclone. Table 1 shows the yield of acrylonitrile, CO ₂ and the run off rate of the catalyst.

Example 3:

Reactor 10 diameter is 12 meters, adopts feed distributor shown in Fig. 6, and the aperture of air outlet is respectively 5.8mm, 5.9mm, 6.0mm, 6.1mm, 6.2mm, 6.3mm, 6.4mm, 6.5mm, adopts For the cooling coil shown in Figure 12, the height of the cooling coil is 7.5m.

The molar ratio of propylene, ammonia and air is 1:1.3:9.7, the reaction pressure is 0.043MPa, the reaction temperature is 435°C, and the operating linear velocity V is 0.9m/s. By weight, catalyst particles with a particle size greater than 90 microns accounted for 7%, particles with a particle size between 45 microns and 90 microns accounted for 58%, particles with a particle size of less than 45 microns accounted for 35%, and particles with a particle size of less than 20 microns accounted for less than 8%. . Entrained catalyst particles were separated from the product using a cyclone. Table 1 shows the yield of acrylonitrile, CO ₂ and the run off rate of the catalyst.

It can be concluded from the above examples that, compared with the prior art, using the reactor and method for producing acrylonitrile of the present invention can greatly increase the yield of acrylonitrile, and can significantly suppress side reactions and reduce the amount of CO ₂ . More importantly, under the condition that the reaction pressure is 0.04-0.05 MPa and the operating linear velocity V is 0.7-1.0 m/s, the catalyst loss rate can be effectively controlled by using the catalyst of the present invention. For example, for every ton of acrylonitrile produced, the loss of catalyst can be at least 0.35kg, which is very beneficial for maintaining the stability of the reaction.

In order to further maintain the stability of the reaction, the fineness distribution of the catalyst in the reactor can be periodically analyzed according to requirements, and catalysts with different finenesses can be added based on the analysis results.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for parts thereof without departing from the scope of the invention. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the patent application.

1‧‧‧Feed distributor

2‧‧‧feed pipe

3‧‧‧air tube

4‧‧‧Air distribution plate

5‧‧‧cooling coil

6‧‧‧Separation device

7‧‧‧Raw gas source

8‧‧‧cold source

10‧‧‧reactor

11‧‧‧reactor body

12‧‧‧Head

Claims (28)

A method for producing acrylonitrile using a reactor for producing acrylonitrile, the reactor for producing acrylonitrile includes: a reactor body, a feed distributor horizontally arranged in the reactor body, and the feed The material distributor includes a pipe group composed of a main pipe and a plurality of branch pipes in fluid communication with the main pipe. Closed, a plurality of air outlet holes are provided on the main pipe and the branch pipe, and an air distribution plate is also arranged below the feed distributor in the main body of the reactor, and the air outlet holes face the air distribution plate, the method comprising: feeding feed gas into the reactor through a feed distributor, and feeding air into the reactor through the air distribution plate, so that the feed gas and air are Under the action of a catalyst, react in the reactor to generate a product containing acrylonitrile, and purify the product containing acrylonitrile to obtain acrylonitrile; in the reactor, the reaction pressure is 0.04 -0.05MPa, and the operating linear velocity V is 0.7-1.0m/s; the fineness distribution of the catalyst is as follows, calculated by weight content, the particles with a particle diameter greater than 90 microns account for 0-30%, and the particle diameter is between 45 microns and Particles with a particle size of 90 microns account for 20-70%, those with a particle size of less than 45 microns account for 30-50%, of which the particle size is less than 20 μm and no more than 10%. The method according to claim 1, wherein, the plurality of outlet holes on the main pipe are configured such that: along the flow direction of the feed gas, the diameter of the downstream outlet holes is larger than the aperture of the upstream outlet holes; and the plurality of outlet holes on the branch pipe The structure of each air outlet is: along the flow direction of the raw material gas, the aperture of the downstream air outlet is larger than the aperture of the upstream air outlet. The method according to claim 2, wherein, on the main pipe, the diameter of any air outlet is greater than or equal to the diameter of the adjacent upstream air outlet; and on the branch pipe, the diameter of any air outlet is greater than or equal to the same The diameter of the adjacent upstream air outlet. The method according to claim 3, wherein, on the main pipe, the ratio of the diameter of any one air outlet to the diameter of the adjacent upstream air outlet is between 1 and 1.08; and on the branch pipe, any one The ratio of the diameter of the air outlet to the diameter of the adjacent upstream air outlet is between 1 and 1.08. The method according to claim 3, wherein, when the diameter of the reactor is 10 to 15 meters, among all the vent holes, the ratio of the diameter of the largest vent hole to the smallest vent hole is between 1.05 and 1.15, when the diameter of the reactor is 5 to 10 meters, among all the vent holes, the ratio of the diameter of the largest vent hole to the smallest vent hole is between 1.02 and 1.13. The method according to claim 2, wherein, on the main pipe, the multiple air outlet holes form a plurality of different air outlet groups, and the air outlet holes in each air outlet group have the same aperture diameter and any one air outlet group The aperture of the air outlet Greater than or equal to the aperture of the air outlet of the adjacent upstream air outlet group; and on the branch pipe, the plurality of air outlets form a plurality of different air outlet groups, and the apertures of the air outlets in each air outlet group are the same and The diameter of the air outlet of any air outlet group is greater than or equal to the aperture of the air outlet of the adjacent upstream air outlet group. The method according to claim 6, wherein, on the main pipe, the ratio of the aperture diameter of any one vent hole group to the vent hole diameter of the adjacent upstream vent hole group is between 1 and 1.08; and On the branch pipe, the ratio of the diameter of the air outlets of any air outlet group to the diameter of the air outlets of the adjacent upstream air outlet group is between 1 and 1.08. The method according to any one of claims 1 to 7, wherein, on the main pipe, along the flow direction in the main pipe, the distances between adjacent air outlets are equal to each other; and on the branch pipe, Along the flow direction in the main pipe, the distances between adjacent air outlets are equal to each other, and the distance between adjacent air outlets on the main pipe is the same as the distance between adjacent air outlets on the branch pipe. The method according to any one of claims 1 to 7, wherein, on the main pipe, one or more air outlet holes are provided at the same circumferential position; and on the branch pipe, at the same circumferential position There are one or more vent holes. The method according to claim 9, wherein, on the main pipe and the branch pipe, a straight guide pipe is installed at each air outlet, and the axis of the straight guide pipe is aligned with the center of the air outlet . The method as claimed in claim 10, wherein, in the supervisor On the same circumferential position, there are two air outlet holes, the angle between the diversion straight pipes corresponding to the two air outlet holes is 30 to 90 degrees, and on the branch pipe, at the same circumferential position There are two air outlet holes, and the included angle between the guide straight pipes corresponding to the two air outlet holes is 30 to 90 degrees. The method according to claim 10, wherein the ends of the straight diversion pipes are in the same plane. The method according to any one of claims 1 to 7, wherein, in the pipe group, the plurality of branch pipes are parallel to each other, and the main pipe is perpendicular to the plurality of branch pipes. The method according to claim 13, wherein, along the axial direction of the main pipe, the vertical distances between adjacent branch pipes are the same. The method according to any one of claims 1 to 7, wherein, in the tube group, the ratio of the length of the branch tubes to the radius of the reactor main body is between 0 and 0.8. The method according to any one of claims 1 to 7, wherein the feed distributor includes the same plurality of pipe groups, each pipe group includes a main pipe and a plurality of branch pipes in fluid communication with the main pipe , the main pipe of each tube group is independently communicated with the raw gas source. The method of claim 16, wherein the main pipes of the plurality of pipe groups are in a first horizontal plane, and the branch pipes of the plurality of pipe groups are in a second horizontal plane different from the first horizontal plane. The method according to claim 16, wherein the plurality of tube groups are evenly distributed in the circumferential direction. The method according to any one of claims 1 to 7, wherein, in the reactor body, an air distribution plate is provided below the feed distributor, and the air outlet faces the air distribution plate. plate. The method according to any one of claims 1 to 7, wherein a cooling coil is provided above the feed distributor in the reactor body. The method according to claim 20, wherein the cooling coils include a plurality of long coils and a plurality of short coils, the length of the long coils is greater than the length of the short coils, and the plurality of Any one of the long coil and the plurality of short coils is independently communicated with a cold source provided outside the reactor body. The method according to claim 21, wherein, in the reactor main body, the short coil and the long coil are arranged in the central area of the cross section of the reactor, and in the cross section of the reactor The long coil pipes are arranged in other areas. The method according to claim 21, wherein any one of the plurality of long coils and the plurality of short coils is composed of one or more U-shaped tubes connected in series, and in terms of the number of U-shaped tubes, the The number of U-shaped tubes in the long coil is 4 to 8, and the number of U-shaped tubes in the short coil is 1 to 3. The method of claim 23, wherein at least one of the long and short coils has an odd number of U-shaped tubes and at least the other has an even number of U-shaped tubes. The method according to claim 1, wherein the catalyst is a Mo-Bi series acrylonitrile catalyst with an average particle size of 40-80 μm. The method according to claim 1, wherein, during the reaction, the fineness distribution of the catalyst in the reactor is analyzed, and the fineness distribution of the catalyst in the reactor is maintained as follows, calculated by weight content , particles with a particle size larger than 90 microns account for 0-30%, particles with a particle size between 45 microns and 90 microns account for 20-70%, and particles with a particle size smaller than 45 microns account for 30-50%, of which the particle size is less than 20 microns. 10%. The method according to claim 1, 25 or 26, wherein, in the reactor, a cooling coil is vertically arranged above the feed distributor, and the fluidization height h of the catalyst is the same as the The operating line speed V conforms to the following relationship:

Wherein, a and b are constants, and the value range of a is 2.5-3.5, and the value range of b is 3.5-4.8, and the height H of the cooling coil is greater than or equal to the fluidization height h of the catalyst. The method as claimed in item 1, 25 or 26, wherein the reaction temperature is 420-460°C, the feed gas is a mixture of propylene and ammonia, and the molar ratio of propylene, ammonia and air is 1:(1.1 -1.3): (9-10.5).

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