CN114471386A

CN114471386A - Ammonolysis reactor and amide preparation method

Info

Publication number: CN114471386A
Application number: CN202210337875.5A
Authority: CN
Inventors: 马磊; 蹇守华; 杨松; 邓龙伟; 周强; 赵丽红; 游林
Original assignee: Southwest Research and Desigin Institute of Chemical Industry
Current assignee: Southwest Research and Desigin Institute of Chemical Industry
Priority date: 2022-04-01
Filing date: 2022-04-01
Publication date: 2022-05-13
Anticipated expiration: 2042-04-01
Also published as: CN114471386B

Abstract

The invention discloses an ammonolysis reactor and an amide preparation method, relating to the technical field of amide preparation, and the technical scheme is as follows: the ammonolysis reactor is characterized in that an inner cavity of a vertically arranged shell is sequentially divided into a liquid inlet cavity, a reaction cavity and a liquid outlet cavity from top to bottom, and the liquid inlet cavity is matched with a liquid-phase ester feeding nozzle and an exhaust nozzle; the reaction cavity is matched with a cooling working medium circulating system, a plurality of reaction tubes are arranged in the reaction cavity, and the reaction tubes are communicated with the liquid inlet cavity and the liquid outlet cavity; a vaporization distributor is arranged in the liquid outlet cavity, each gas outlet end of the vaporization distributor is connected with the lower end of the corresponding reaction tube, and the lower end of the reaction tube is provided with an overflow channel; the lower end of the liquid outlet cavity is matched with a product discharge nozzle and an ammonia liquid feeding nozzle, the ammonia liquid feeding nozzle is connected with the feeding end of the vaporization distributor, and ammonia gas and liquid-phase ester flow reversely in the reaction tube during use, so that efficient ammonolysis reaction is realized, a plurality of reaction kettles do not need to be connected in series, and the investment and the occupied area of equipment can be reduced. The amide preparation method is based on the ammonolysis reactor, and can reduce the production cost.

Description

Ammonolysis reactor and amide preparation method

Technical Field

The invention relates to the technical field of amide preparation, and particularly relates to an ammonolysis reactor and an amide preparation method.

Background

An amide is an important organic compound having an amide bond, and can be structurally considered to be a compound in which a hydroxyl group on a carboxyl group is substituted with an amino group or an alkylamino group. Amides generally have a high boiling point, low melting point, and are liquid at ambient temperature and are often used as high boiling solvents in chemical reactions, such as N, N-dimethylformamide. In addition, N-dimethylformamide has excellent solubility, and can dissolve various organic substances, so that it is called "universal solvent".

The synthesis method of the amide mainly comprises the following two types:

1) the ammonolysis method comprises acyl halide ammonolysis, acid anhydride ammonolysis, ester ammonolysis and the like. The ammonolysis method is the most classical amide preparation method, and has the characteristics of mild reaction conditions, low raw material cost and the like, wherein the ester ammonolysis method has the lowest reaction activity and needs longer time to obtain better yield under the preparation conditions.

2) Nitrile compounds, which are organic compounds containing a cyano group, generally have a relatively high toxicity. The nitrile hydrolysis method is to hydrolyze under strong acid or strong alkaline conditions to generate amide. However, since the amide is easily hydrolyzed into carboxylic acid and amine under strong acid or alkaline condition, and the reaction is strongly exothermic, the reaction is not easy to control and has very high toxicity.

In conclusion, the nitrile hydrolysis method has the advantages of higher safety risk, violent reaction, difficult control and more side reactions, so that the ammonolysis method is obviously superior to the nitrile hydrolysis method. However, the ester ammonolysis method has low reaction activity and needs longer residence time, so that the prior ester ammonolysis method adopts a preparation system (shown in figure 1) in which a plurality of kettle-type reactors with stirrers are connected in series, and has large equipment investment and large occupied area.

Disclosure of Invention

Aiming at the problems of large equipment investment and technical problem of the prior ammonolysis method for producing amide; the invention provides an ammonolysis reactor and an amide preparation method, a plurality of reaction kettles do not need to be connected in series, and the reactor shell is vertically arranged, so that the investment of equipment can be reduced, the floor area of the equipment is reduced, the production cost of amide is reduced, and the land resource is saved.

The invention is realized by the following technical scheme:

in a first aspect, the invention provides an ammonolysis reactor, which comprises a vertically arranged shell, wherein an inner cavity of the shell is sequentially divided into a liquid inlet cavity, a reaction cavity and a liquid outlet cavity from top to bottom; the liquid inlet cavity is matched with a liquid-phase ester feeding nozzle, and the top of the liquid inlet cavity is provided with an exhaust nozzle; the reaction cavity is matched with a cooling working medium circulating system, a plurality of reaction tubes are arranged in the reaction cavity, and the reaction tubes are communicated with the liquid inlet cavity and the liquid outlet cavity; a vaporization distributor is arranged in the liquid outlet cavity, each gas outlet end of the vaporization distributor is connected with the lower end of the corresponding reaction tube, and the lower end of the reaction tube is provided with an overflow channel; and the lower end of the liquid outlet cavity is matched with a product discharging nozzle and an ammonia liquid feeding nozzle, and the ammonia liquid feeding nozzle is connected with the feeding end of the vaporization distributor.

When the ammonolysis reactor provided by the invention is used, liquid-phase ester enters the liquid inlet cavity through the liquid-phase ester feeding nozzle so as to form a liquid level in the liquid inlet cavity, part of the liquid-phase ester enters the reaction tube under the action of gravity, meanwhile, the cooling working medium is circularly fed into the reaction cavity through the cooling working medium circulating system matched with the reaction cavity to cool the reaction cavity, and liquid ammonia enters the reaction tube after being vaporized by the vaporization distributor in the liquid outlet cavity so that ammonia gas flows reversely in the reaction tube, so that the ammonolysis reaction is efficient.

Wherein, the liquid ammonia enters the reaction tube to flow reversely after being vaporized and uniformly distributed in the vaporization distributor, the resistance of liquid-phase ester in the reaction tube can be overcome by the pressure after the liquid ammonia is vaporized, the reaction ammonia concentration of each axial point in the reaction tube is kept approximate, the conversion rate of ammonolysis reaction in the reaction tube can be ensured, and the local overheating of the reaction tube is avoided; the liquid phase ester feeding forms the liquid level in the feed liquor intracavity to be full of the reaction tube, with through liquid phase ester liquid seal ammonia, prevent that the ammonia from escaping when guaranteeing that the reaction high efficiency goes on, can reduce ammonia escape rate by a wide margin, not only practice thrift manufacturing cost, can the environmental protection moreover.

In an alternative embodiment, the upper part of the liquid inlet cavity is provided with a first liquid phase distributor, and the liquid inlet end of the first liquid phase distributor is connected with the discharge end of the liquid phase ester feeding nozzle so as to disperse the liquid phase ester entering the liquid inlet cavity and absorb the ammonia penetrating through the liquid level.

In an optional embodiment, a second liquid phase distributor is further disposed at the upper portion of the liquid inlet cavity, and the second liquid phase distributor is located below the first liquid phase distributor to disperse the liquid phase ester dispersed in the first liquid phase distributor to form liquid drops with smaller particle sizes, so that a contact area between the liquid phase ester and ammonia is increased, reaction efficiency and a capture rate of ammonia gas penetrating through the liquid level are improved, and an escape rate of the ammonia gas is further reduced.

In an alternative embodiment, the upper part of the liquid inlet chamber is provided with a demister so as to break up bubbles through the demister and prevent the liquid-phase ester from being carried out of the reactor by the gas discharged from the gas exhaust nozzle.

In an optional embodiment, the reaction chamber is adapted with a cooling working medium inlet and a cooling working medium outlet; the cooling working medium inlet is positioned at the lower end of the reaction cavity, and the cooling working medium outlet is positioned at the upper end of the reaction cavity, so that the reaction tube is fully cooled by the cooling working medium.

In an alternative embodiment, the vaporization distributor is a butterfly box configuration to ensure that liquid ammonia is vaporized in the distributor and evenly distributed to each outlet.

In an optional embodiment, the vaporization distributor is vertically provided with a plurality of liquid descending channels to ensure that liquid amide generated by the reaction smoothly enters the bottom of the liquid outlet cavity through the vaporization distributor.

In an optional embodiment, the liquid outlet end of the vaporization distributor is connected with a plurality of pulse distribution pipes, and the gas outlet end of each pulse distribution pipe is connected with the lower end of the reaction pipe so as to connect the vaporization distributor and the reaction pipe through pulse distribution.

In an optional embodiment, the outlet of the pulse distribution pipe is a necking opening to improve the initial speed of ammonia gas entering the reaction pipe, improve the distribution rate of ammonia gas in the reaction pipe, and effectively prevent liquid-phase ester from flowing backwards from the inlet of the pulse distribution pipe to enter the vaporization distributor.

In a second aspect, the present invention provides a process for preparing an amide, comprising the steps of:

s1, feeding liquid-phase amide into a liquid inlet cavity at the upper end of a shell of the reactor, wherein the shell is vertically arranged, an inner cavity of the shell is sequentially divided into the liquid inlet cavity, a reaction cavity and a liquid outlet cavity from top to bottom, and the liquid inlet cavity and the liquid outlet cavity are communicated through a reaction pipe inserted in the reaction cavity;

s2, connecting a cooling system with the reaction cavity, and cooling the reaction tube through a cooling working medium;

and S3, sending liquid-phase ammonia into a vaporization distributor in the liquid outlet cavity, and sending the liquid-phase ammonia into the reaction tube through the vaporization distributor to carry out ammonolysis reaction to generate amide.

The amide preparation method provided by the invention is based on the ammonolysis reactor, can reduce the investment of equipment and the occupied area of the equipment so as to reduce the production cost of amide and save land resources, can overcome the resistance of liquid-phase ester in the reaction tube through the pressure after liquid ammonia is vaporized, keeps the similar concentration of the reaction ammonia at each axial point in the reaction tube, can ensure the conversion rate of the ammonolysis reaction in the reaction tube, simultaneously avoids local overheating of the reaction tube, can greatly reduce the escape rate of ammonia, saves the production cost and protects the environment.

The invention has the following beneficial effects:

1. the ammonolysis reactor provided by the invention has the advantages that the inner cavity of the vertically arranged shell is sequentially divided into a liquid inlet cavity, a reaction cavity and a liquid outlet cavity from top to bottom, and the liquid inlet cavity is matched with a liquid-phase ester feeding nozzle and an exhaust nozzle; the reaction cavity is matched with a cooling working medium circulating system, a plurality of reaction tubes are arranged in the reaction cavity, and the reaction tubes are communicated with the liquid inlet cavity and the liquid outlet cavity; a vaporization distributor is arranged in the liquid outlet cavity, each gas outlet end of the vaporization distributor is connected with the lower end of the corresponding reaction tube, and the lower end of the reaction tube is provided with an overflow channel; go out liquid chamber lower extreme adaptation and have product ejection of compact to chew and ammonia liquid feed nozzle, the ammonia liquid feed nozzle links to each other with the feed end of vaporization distributor, so that liquid phase ester forms the liquid seal in the feed liquor intracavity and gets into in the reaction tube, liquid ammonia gets into the reaction tube and flows against the current after vaporization distributor vaporization equipartition, thereby the efficient aminolysis is reacted, and the coolant that is provided by cooling system cools off, do not need a plurality of reation kettle of establishing ties, and the vertical setting of reactor shell, can reduce the investment of equipment, reduce the area of equipment, with the manufacturing cost who reduces amide and saving land resource.

2. When the ammonolysis reactor provided by the invention is used, liquid-phase ester forms a liquid seal in the liquid inlet cavity and enters the reaction tube, liquid ammonia is vaporized and uniformly distributed in the vaporization distributor and then enters the reaction tube in a countercurrent manner, the resistance of the liquid-phase ester in the reaction tube can be overcome by the pressure after the liquid ammonia is vaporized, the reaction ammonia concentration at each axial point in the reaction tube is kept approximate, the conversion rate of ammonolysis reaction in the reaction tube can be ensured, and meanwhile, the local overheating of the reaction tube is avoided.

3. When the ammonolysis reactor provided by the invention is used, liquid-phase ester forms a liquid level in the liquid inlet cavity and enters the reaction tube, liquid ammonia is vaporized and uniformly distributed in the vaporization distributor and then enters the reaction tube for countercurrent, so that ammonia gas is sealed by the liquid-phase ester liquid, the reaction is ensured to be carried out efficiently, the ammonia gas is prevented from escaping, the ammonia escape rate can be greatly reduced, the production cost is saved, and the environment can be protected.

4. The amide preparation method provided by the invention is based on the ammonolysis reactor, can reduce the investment of equipment and the occupied area of the equipment so as to reduce the production cost of amide and save land resources, can overcome the resistance of liquid-phase ester in the reaction tube through the pressure after liquid ammonia is vaporized, keeps the similar concentration of the reaction ammonia at each axial point in the reaction tube, can ensure the conversion rate of the ammonolysis reaction in the reaction tube, simultaneously avoids local overheating of the reaction tube, can greatly reduce the escape rate of ammonia, saves the production cost and protects the environment.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

FIG. 1 is a schematic structural diagram of a conventional preparation system for preparing amide by aminolysis based on a plurality of stirred reactors connected in series;

FIG. 2 is a schematic view of the configuration of an ammonolysis reactor according to an embodiment of the present invention;

FIG. 3 is an enlarged view of portion A of FIG. 2;

FIG. 4 is a schematic diagram of a vaporization distributor according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a pulse distribution tube according to an embodiment of the present invention.

Reference numerals:

10-a reaction kettle, 11-a stirrer and 12-an aging tank;

20-shell, 21-liquid inlet cavity, 211-liquid level detection interface, 22-liquid phase ester feeding nozzle, 23-exhaust nozzle, 24-reaction cavity, 25-liquid outlet cavity, 26-product discharging nozzle, 27-liquid ammonia feeding nozzle, 28-cooling working medium inlet and 29-cooling working medium outlet;

30-reaction tube, 31-overflow;

40-a vaporization distributor, 41-a liquid descending channel and 42-a pulse distribution pipe;

50-a first liquid phase distributor;

60-a second liquid phase distributor;

70-demister.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. The directions or positional relations indicated in the drawings are directions or positional relations based on the drawings, or directions or positional relations which are usually placed when the products of the application are used, or directions or positional relations which are usually understood by those skilled in the art. The terms "disposed", "open", "mounted", "connected" and "connected" are to be understood in a broad sense.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. And the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

In the prior amide products, amide containing double bonds, such as acrylamide, can be used for preparing polyacrylamide, and the polyacrylamide is a water-soluble high-molecular polymer and can be used as a drag reducer for reducing friction in liquid in the process of petroleum tubular transportation.

In addition, amide herbicides such as dimethenamid, flufenacet, dimethenamid and the like can be used as herbicides in agricultural fields, and the amount and area of use of amide herbicides have been increased in recent years to the second place where organophosphorus herbicides are located. The long-chain amide can be used as a surfactant to be added into detergents such as shampoo, bath lotion, shaving products and the like to be used as a thickening agent and a foam stabilizer; the surface activity can also be enhanced by further adding other active groups such as amino, carboxyl and the like.

Therefore, the cost for preparing the amide is reduced, and the method has great technical and economic values. The common urethane ammonolysis method has the advantages of easily obtained raw materials and low cost; the reaction is mild, and the operation is easy; the exothermic quantity is small, and the method is friendly to heat-sensitive amide products, so that the method becomes the most main amide synthesis process flow. However, the conventional ester ammonolysis method adopts a preparation system (shown in figure 1) in which a plurality of tank reactors with stirrers are connected in series, so that the equipment investment is large and the occupied area is large. In view of this, the present invention provides an aminolysis reactor and an amide preparation method, specifically referring to the following examples:

example 1

With reference to fig. 2, the embodiment provides an ammonolysis reactor, which includes a vertically arranged housing 20, wherein an inner cavity of the housing 20 is sequentially divided into a liquid inlet cavity 21, a reaction cavity 24 and a liquid outlet cavity 25 from top to bottom; the liquid inlet cavity 21 is matched with a liquid-phase ester feeding nozzle 22, and the top of the liquid inlet cavity 21 is provided with an exhaust nozzle 23; the reaction cavity 24 is adapted with a cooling working medium circulating system, a plurality of reaction tubes 30 are arranged in the reaction cavity 24, and the reaction tubes 30 are communicated with the liquid inlet cavity 21 and the liquid outlet cavity 25; a vaporization distributor 40 is arranged in the liquid outlet cavity 25, each gas outlet end of the vaporization distributor 40 is connected with the lower end of the corresponding reaction tube 30, and the lower end of the reaction tube 30 is provided with an overflow channel 31; the lower end of the liquid outlet cavity 25 is adapted with a product discharge nozzle 26 and an ammonia liquid feeding nozzle which is connected with the feeding end of the vaporization distributor 40.

Specifically, the liquid-phase ester feed nozzle 22 is connected to a liquid-phase ester supply device so that the liquid-phase ester is introduced into the liquid inlet chamber 21 through the liquid-phase ester feed nozzle 22 to form a liquid level in the liquid inlet chamber 21. Because the reaction tube 30 is communicated with the liquid inlet cavity 21 and the liquid outlet cavity 25, part of the liquid-phase ester enters the reaction tube 30 under the action of gravity, and forms a continuous liquid phase to fill the whole reaction tube 30.

In order to detect the liquid level of the liquid-phase grease in the liquid inlet cavity 21 and ensure the complete ammonolysis reaction, a liquid level detection interface 211 is further arranged on the side wall of the liquid inlet cavity 21, and two liquid level detection interfaces 211 are usually arranged in the height direction of the liquid inlet cavity 21 at intervals so as to judge whether the liquid level in the liquid inlet cavity 21 is in a set range.

In order to facilitate the connection of a cooling working medium circulation system, the reaction chamber 24 is matched with a cooling working medium inlet 28 and a cooling working medium outlet 29; the cooling working medium inlet 28 is positioned at the lower end of the reaction cavity 24, and the cooling working medium outlet 29 is positioned at the upper end of the reaction cavity 24, so that the cooling working medium can sufficiently cool the reaction tube 30, heat can be transferred through the cooling working medium, the ammonolysis reaction can be facilitated, and the conversion rate and the safety risk can be reduced.

For the cooling working medium in the cooling working medium circulation system, the cooling working medium is determined according to various factors such as optimal reaction temperature, reaction adiabatic temperature rise, reactant heat sensitivity, influence degree of temperature on side reaction and the like, for example, refrigerants such as circulating cooling water, chilled water, heat conduction oil, boiler feed water, steam and the like are introduced, and a flow-around part such as a baffle plate and the like can be arranged in the shell 20 for enhancing heat transfer, so that the cooling working medium can be fully contacted with the reaction tube 30.

The vaporization distributor 40 only needs to vaporize the liquid ammonia and feed the liquid ammonia into each reaction tube 30, and a normal temperature distributor is generally used because the temperature required for vaporizing the liquid ammonia is low and heat is released during the ammonolysis reaction. The upper end of the distributor is provided with a plurality of air outlets which are connected with the corresponding reaction tubes 30, so that the liquid can be discharged from the overflow channel 31 at the lower end of the reaction tubes 30.

When the ammonolysis reactor provided by the embodiment is used, liquid-phase ester enters the liquid inlet cavity 21 through the liquid-phase ester feeding nozzle 22, and meanwhile, the cooling working medium is circularly sent into the reaction cavity 24 through the cooling working medium circulating system adaptive to the reaction cavity 24 to cool the reaction cavity 24, and liquid ammonia enters the reaction tube 30 after being vaporized by the vaporization distributor 40 in the liquid outlet cavity 25, so that ammonia gas flows reversely in the reaction tube 30, and the efficient ammonolysis reaction is realized. The product generated by the reaction enters an overflow channel 31 at the lower end of the reaction tube 30 and is discharged to the bottom of the liquid outlet cavity 25, the product is discharged and collected through a product discharge nozzle 26 at the bottom of the liquid outlet cavity 25, and the gas which is not completely reacted is discharged through an exhaust nozzle 23 at the top of the liquid inlet cavity 21.

Therefore, the liquid level in the liquid inlet cavity 21 is controlled by a valve on a pipeline of the product discharging nozzle 26 and can be adjusted according to the static head of the fed liquid ammonia, so that the high-efficiency reaction is ensured; the ammonolysis reaction pressure is accurately controlled by controlling the pipeline pressure of the exhaust nozzle 23.

In conclusion, the ammonolysis reactor provided by the embodiment does not need to be connected with a plurality of reaction kettles 10 in series, and the reactor shell 20 is vertically arranged, so that the investment of equipment can be reduced, the floor area of the equipment is reduced, the production cost of amide is reduced, and the land resource is saved; liquid ammonia is vaporized and uniformly distributed in the vaporization distributor 40 and then enters the reaction tube 30 to flow reversely, so that the resistance of liquid-phase ester in the reaction tube 30 can be overcome through the pressure after the liquid ammonia is vaporized, the reaction ammonia concentration at each axial point in the reaction tube 30 is kept approximate, the conversion rate of ammonolysis reaction in the reaction tube 30 can be ensured, and the local overheating of the reaction tube 30 is avoided; the liquid phase ester feeding forms the liquid level in feed liquor chamber 21 to be full of reaction tube 30, with through liquid phase ester liquid seal ammonia, prevent that the ammonia from escaping when guaranteeing that the reaction high efficiency goes on, can reduce ammonia escape rate by a wide margin, not only practice thrift manufacturing cost, can protect the environment moreover.

Example 2

With reference to fig. 2, the present embodiment provides an ammonolysis reactor, based on the structure and principle described in embodiment 1, the upper portion of the liquid inlet chamber 21 is provided with a first liquid phase distributor 50, and the liquid inlet end of the first liquid phase distributor 50 is connected to the discharge end of the liquid phase ester feeding nozzle 22 to disperse the liquid phase ester entering the liquid inlet chamber 21, thereby absorbing the ammonia gas penetrating through the liquid level.

Further, a second liquid phase distributor 60 is further disposed at the upper portion of the liquid inlet cavity 21, and the second liquid phase distributor 60 is located below the first liquid phase distributor 50 to disperse the liquid phase ester dispersed in the first liquid phase distributor 50 to form liquid drops with smaller particle sizes, so that the contact area between the liquid phase ester and ammonia is increased, the reaction efficiency and the capture rate of ammonia penetrating through the liquid level are improved, and the escape rate of ammonia is further reduced.

It will be appreciated that the first liquid phase distributor 50, as the primary distributor, may be a straight connecting pipe or loop with mesh, although a distributor disk may be used. When the distribution plate is used as the first liquid phase distributor 50, it is necessary to ensure that a gas passing channel is arranged between the first liquid phase distributor 50 and the side wall of the liquid inlet cavity 21 or the first liquid phase distributor 50 itself, so that the incompletely reacted gas can be discharged out of the housing 20, and the production safety is ensured.

For the second liquid phase distributor 60, a structure capable of forming the liquid phase ester into fog drops, such as a fine-pore mesh plate, is adopted, so that the liquid flow passes through the second liquid phase distributor 60 to form continuous fog drops with the diameter less than or equal to 2mm, the contact area of the liquid flow and the ammonia penetrating through the liquid level of the liquid inlet cavity 21 is increased, and the escape of the ammonia is reduced.

Example 3

In connection with fig. 2, this embodiment provides an ammonolysis reactor, and based on the structure and principle described in embodiment 1 or 2, the upper part of the liquid inlet chamber 21 is equipped with a demister 70, such as a mesh plate demister 70, a wire mesh demister 70, a sponge demister 70, etc., to break up bubbles by the demister 70 and prevent the liquid-phase ester from being carried out of the reactor by the gas discharged from the gas discharge nozzle 23.

It should be noted that the demister 70 should be disposed at the air inlet end of the exhaust nozzle 23, that is, when the first liquid phase distributor 50 is disposed in the liquid inlet chamber 21, the demister 70 is located above the first liquid phase distributor 50.

Example 4

In conjunction with fig. 3 and 4, this embodiment provides an ammonolysis reactor, based on the structure and principle described in any of embodiments 1-3, the vaporization distributor 40 is a butterfly box structure to ensure that liquid ammonia is vaporized in the distributor and uniformly distributed to each outlet.

It should be understood that the vaporizing distributor 40 is a disk-shaped box structure, and the distributor is gradually flattened from the center along the radial direction to ensure that the gas phase velocities at all positions are equal, so that the vaporizing pressure and the flow rate at all points in the distributor at different distances from the center are the same, and the problem of bias flow in the reaction tube 30 is avoided.

On the basis, the vaporization distributor 40 is vertically provided with a plurality of liquid descending channels 41 to ensure that the liquid amide generated by the reaction smoothly enters the bottom of the liquid outlet cavity 25 through the vaporization distributor 40 and does not contact with the gas-liquid phase ammonia raw material in the vaporization distributor 40.

Referring to fig. 4, the liquid outlet end of the vaporization distributor 40 is connected to a plurality of pulse distribution pipes 42, and the gas outlet end of the pulse distribution pipes 42 is connected to the lower end of the reaction pipe 30 to connect the vaporization distributor 40 and the reaction pipe 30 by pulse distribution. In order to simplify the structure of the reaction tube 30, the upper end of the pulse distribution tube 42 is in clearance fit with the lower end of the reaction tube 30, and the clearance between the upper end of the pulse distribution tube 42 and the lower end of the reaction tube 30 is used as the overflow channel 31.

Referring to fig. 5, the outlet of the pulse distribution tube 42 is a necking opening to increase the initial velocity of the ammonia gas entering the reaction tube 30, increase the distribution rate of the ammonia gas in the reaction tube 30, and effectively prevent the liquid-phase ester from flowing backward from the inlet of the pulse distribution tube 42 into the vaporization distributor 40.

In the vaporization distributor 40 provided in this embodiment, when the liquid ammonia enters the vaporization distributor 40, the liquid ammonia is vaporized and evenly distributed to each pulse branch pipe, and then the ammonia gas is accelerated by the pulse branch pipes and then sent into the reaction tube 30, so that the ammonia gas in the reaction tube 30 can axially rise along with the reaction tube 30 and evenly distribute; and the liquid ammonia is vaporized and pulse-accelerated, and then the liquid ammonia is in countercurrent contact in the reaction tube 30 to carry out ammonolysis reaction, while the liquid phase is a continuous phase and fills the whole reaction tube 30, the gas phase is used as a dispersed phase and is pushed by pressure to move upwards along the axial direction, and the pressure of the gas phase pipeline at the outlet of the reactor is controlled to enable the dispersed phase pushing force in the reactor to be controllable and meet the requirement of consistent reaction depth of axial points in the reaction tube 30, so that the reaction efficiency is fully improved.

Example 5

This example provides a process for the preparation of an amide, based on the ammonolysis reactor and ammonolysis process provided in the preceding examples, comprising the steps of:

s1, feeding liquid-phase amide into a liquid inlet cavity 21 at the upper end of a shell 20 of the reactor, wherein the shell 20 is vertically arranged, the inner cavity of the shell 20 is sequentially divided into the liquid inlet cavity 21, a reaction cavity 24 and a liquid outlet cavity 25 from top to bottom, and the liquid inlet cavity 21 is communicated with the liquid outlet cavity 25 through a reaction pipe 30 inserted in the reaction cavity 24.

Specifically, the liquid-phase ester feed nozzle 22 is connected with a liquid-phase ester supply device, so that the liquid-phase ester enters the liquid inlet cavity 21 through the liquid-phase ester feed nozzle 22 to form a liquid level in the liquid inlet cavity 21; because the reaction tube 30 is communicated with the liquid inlet cavity 21 and the liquid outlet cavity 25, part of the liquid-phase ester enters the reaction tube 30 under the action of gravity, and forms a continuous liquid phase to fill the whole reaction tube 30.

And S2, connecting a cooling system with the reaction cavity 24, and cooling the reaction tube 30 by the cooling working medium.

Specifically, the cooling working medium in the cooling working medium circulation system is determined according to various factors such as the optimal reaction temperature, the adiabatic temperature rise of the reaction, the heat sensitivity of the reactant, the degree of influence of the temperature on the side reaction and the like, for example, a cooling medium such as circulating cooling water, chilled water, heat conduction oil, boiler feed water, steam and the like is introduced, and a flow-around part such as a baffle plate and the like can be arranged in the shell 20 for enhancing heat transfer, so that the cooling working medium is fully contacted with the reaction tube 30.

S3, sending liquid-phase ammonia into the vaporization distributor 40 in the liquid outlet cavity 25, and sending the liquid-phase ammonia into the reaction tube 30 through the vaporization distributor 40 to carry out ammonolysis reaction to generate amide.

Specifically, the liquid ammonia is vaporized by the vaporization distributor 40 in the liquid outlet chamber 25 and then enters the reaction tube 30, so that the ammonia gas flows in a counter-current manner in the reaction tube 30, thereby performing the efficient ammonolysis reaction.

In order to facilitate understanding of the beneficial technical effects of the present embodiment, experimental comparison is performed by using specific production examples and comparative examples, which are as follows:

production example:

based on the ammonolysis reactor (figure 2), 2.0MPa (G), about 2700kg/h of liquid ammonia at 30 ℃ enters the vaporization distributor 40 from the liquid ammonia feed nozzle 27, is vaporized by the vaporization distributor 40, and then enters the bottom of the counter-current reaction tube 30 from the pulse distribution tube 42; 0.3MPa (G), about 9500kg/h of raw material methyl formate at the temperature of 30 ℃ enters a first liquid phase distributor 50 from a liquid phase ester feeding hole, then the raw material methyl formate is dispersed into uniform small liquid drops with the diameter less than or equal to 2mm through a second liquid phase distributor 60, and then the reaction tube 30 is gradually filled and the liquid level is formed in a liquid inlet cavity 21. The reaction product flows downwards to the bottom of the liquid inlet cavity 21 under gravity and is discharged through the product discharging nozzle 26. Meanwhile, the circulating cooling water with the temperature of 32 ℃ and the pressure of 0.4MPa (G) enters the reaction chamber 24 from the cooling working medium inlet 28, and the circulating cooling water with the temperature of 40 ℃ and the pressure of 0.35MPa (G) leaves the reaction chamber 24 from the cooling working medium outlet 29.

Wherein the formamide reactor capacity is about 7200kg/h and the reactor size is as follows: the reaction tube 30 (the height of the countercurrent reaction section is 9 m) and the inner diameter of the reactor is 1.8 m. The conversion per pass in the reaction is about 98.3 percent, and the escape rate of ammonia is less than or equal to 0.1 percent (wt percent). The amount of the circulating cooling water is about 340 t/h.

Comparative example:

based on the prior multistage kettle type ammonolysis reactor for producing formamide, three kettle type serial ammonolysis reactors and one aging tank 12 are arranged in combination with figure 1, the kettle type ammonolysis reactors are all provided with an electric stirrer 11, a cooling water jacket and a freezing water sleeve, and the aging tank 12 is a horizontal container.

2.0MPa (G), about 2000kg/h of liquid ammonia at 30 ℃ enters a primary reaction kettle 10 from a liquid ammonia feed pipeline, 0.3MPa (G), about 9500kg/h of methyl formate at 30 ℃ enters the primary reaction kettle 10 from a methyl formate feed pipeline, the raw materials are mixed in the primary reaction kettle 10 and are continuously stirred by a stirrer 11, simultaneously, 32 ℃ and 0.4MPa (G) circulating cooling water are introduced into an outer cooling water jacket, and 0 ℃ and 0.4MPa (G) freezing water are introduced into an inner freezing water jacket for heat transfer.

The reaction mixture flows into a secondary reaction kettle 10 from an outlet of a primary reaction kettle 10, meanwhile, about 700kg/h of liquid ammonia enters the secondary reaction kettle 10 from a liquid ammonia feed pipeline, the secondary reaction kettle 10 is also stirred by a stirrer 11, cooling water and chilled water are used for heat transfer, the reaction mixture flows into a final reaction kettle 10 from an outlet of the secondary reaction kettle 10, the final reaction kettle 10 is stirred by the stirrer 11, and after the cooling water and the chilled water are used for heat transfer, the reaction mixture is sent into an aging tank 12 from an outlet pipeline for standing and aging, and then the whole reaction process is completed.

Wherein, in order to reduce ammonia escape in the reaction process, a nitrogen pressurizing pipeline is added at the upper part of the reactor.

This comparative example is about 7200kg/h formamide reaction scheme, with the following reactor dimensions: the volumes of the three reaction kettles 10 are all 40m³An internal diameter of about 2.8 meters and a height of about 6.5 meters. The aging tank 12 has a volume of about m³The inner diameter is about 3 meters, and the tangent length is about 13.2 meters. The conversion per pass in the reaction is about 98.5 percent, and the escape rate of ammonia is less than or equal to 1 percent (wt percent). The dosage of the circulating cooling water is about 120t/h, and the dosage of the freezing water is about 280 t/h.

In comparison, the method and the device for improving work in the embodiment have the equivalent single-pass conversion rate in the reaction, and when the ammonia gas escape rate is one tenth of the existing one.

In conclusion, the ammonolysis reactor provided by the embodiment does not need to be connected with a plurality of reaction kettles 10 in series, and the reactor shell 20 is vertically arranged, so that the investment of equipment can be reduced, the floor area of the equipment is reduced, the production cost of amide is reduced, and the land resource is saved; greatly reduces the escape rate of ammonia, not only saves the production cost, but also protects the environment.

The foregoing is only a preferred embodiment of the invention, and is not intended to limit the invention in any way, so that any simple modification, equivalent replacement, or improvement made to the above embodiment within the spirit and principle of the invention will still fall within the protection scope of the invention.

Claims

1. An ammonolysis reactor is characterized by comprising a vertically arranged shell (20), wherein the inner cavity of the shell (20) is sequentially divided into a liquid inlet cavity (21), a reaction cavity (24) and a liquid outlet cavity (25) from top to bottom;

the liquid inlet cavity (21) is matched with a liquid-phase ester feeding nozzle (22), and the top of the liquid inlet cavity (21) is provided with an exhaust nozzle (23);

the reaction cavity (24) is matched with a cooling working medium circulating system, a plurality of reaction tubes (30) are arranged in the reaction cavity (24), and the reaction tubes (30) are communicated with the liquid inlet cavity (21) and the liquid outlet cavity (25);

a vaporization distributor (40) is arranged in the liquid outlet cavity (25), each gas outlet end of the vaporization distributor (40) is connected with the lower end of the corresponding reaction tube (30), and the lower end of the reaction tube (30) is provided with an overflow channel (31);

the lower end of the liquid outlet cavity (25) is matched with a product discharging nozzle (26) and an ammonia liquid feeding nozzle, and the ammonia liquid feeding nozzle is connected with the feeding end of the vaporization distributor (40).

2. The ammonolysis reactor according to claim 1, wherein a first liquid phase distributor (50) is disposed above said inlet chamber (21), and the inlet end of said first liquid phase distributor (50) is connected to the outlet end of said liquid phase ester feed nozzle (22).

3. Ammonolysis reactor according to claim 2, wherein a second liquid phase distributor (60) is provided above the inlet chamber (21), said second liquid phase distributor (60) being located below the first liquid phase distributor (50).

4. Ammonolysis reactor according to any of claims 1 to 3, characterized in that the upper part of the inlet chamber (21) is fitted with a demister (70).

5. Ammonolysis reactor according to claim 1, characterized in that the reaction chamber (24) is adapted with a cooling medium inlet (28) and a cooling medium outlet (29);

the cooling working medium inlet (28) is positioned at the lower end of the reaction cavity (24), and the cooling working medium outlet (29) is positioned at the upper end of the reaction cavity (24).

6. Ammonolysis reactor according to claim 1, characterized in that the vaporization distributor (40) is of butterfly box type construction.

7. Ammonolysis reactor according to claim 1 or 6, characterized in that the vaporizing distributor (40) is vertically provided with a plurality of downcomer channels (41).

8. The ammonolysis reactor according to claim 1, wherein a plurality of pulse distribution pipes (42) are connected to the liquid outlet end of the vaporization distributor (40), and the gas outlet ends of the pulse distribution pipes (42) are connected to the lower ends of the reaction pipes (30).

9. Ammonolysis reactor according to claim 8, characterized in that the pulse distribution tube (42) outlet is a necked-down.

10. A method for preparing amide is characterized by comprising the following steps:

s1, feeding liquid-phase amide into a liquid inlet cavity (21) at the upper end of a reactor shell (20), wherein the shell (20) is vertically arranged, the inner cavity of the shell (20) is sequentially divided into the liquid inlet cavity (21), a reaction cavity (24) and a liquid outlet cavity (25) from top to bottom, and the liquid inlet cavity (21) and the liquid outlet cavity (25) are communicated through a reaction pipe (30) inserted into the reaction cavity (24);

s2, connecting a cooling system with the reaction cavity (24), and cooling the reaction tube (30) through a cooling working medium;

s3, sending liquid-phase ammonia into a vaporization distributor (40) in the liquid outlet cavity (25), and sending the liquid-phase ammonia into the reaction tube (30) through the vaporization distributor (40) to carry out ammonolysis reaction to generate amide.