CN115106043B - Device, system and method for preparing difluoroethane by continuous reaction - Google Patents

Device, system and method for preparing difluoroethane by continuous reaction Download PDF

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CN115106043B
CN115106043B CN202210743715.0A CN202210743715A CN115106043B CN 115106043 B CN115106043 B CN 115106043B CN 202210743715 A CN202210743715 A CN 202210743715A CN 115106043 B CN115106043 B CN 115106043B
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reaction kettle
liquid
hydrogen fluoride
gas
difluoroethane
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CN115106043A (en
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张亮亮
初广文
张一栋
陈建峰
孙宝昌
邹海魁
罗勇
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Beijing University of Chemical Technology
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Beijing University of Chemical Technology
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    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/07—Preparation of halogenated hydrocarbons by addition of hydrogen halides
    • C07C17/087—Preparation of halogenated hydrocarbons by addition of hydrogen halides to unsaturated halogenated hydrocarbons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/009—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping in combination with chemical reactions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
    • B01D3/322—Reboiler specifications
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/18—Absorbing units; Liquid distributors therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/18—Stationary reactors having moving elements inside
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J4/00—Feed or outlet devices; Feed or outlet control devices
    • B01J4/001—Feed or outlet devices as such, e.g. feeding tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/0015—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/0015—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor
    • B01J8/0035—Periodical feeding or evacuation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
    • B01J8/10—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles moved by stirrers or by rotary drums or rotary receptacles or endless belts
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/07—Preparation of halogenated hydrocarbons by addition of hydrogen halides
    • C07C17/08—Preparation of halogenated hydrocarbons by addition of hydrogen halides to unsaturated hydrocarbons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00002—Chemical plants
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Abstract

The invention discloses a device, a system and a method for preparing difluoroethane by continuous reaction, wherein the system comprises a hydrogen fluoride liquid inlet, an acetylene gas inlet, a reaction kettle, a first condenser, a circulating pump, a second condenser, an absorbing device, a reboiler, a rectifying tower, a third condenser, a difluoroethane outlet and a lifting pump, wherein the hydrogen fluoride liquid inlet is connected with the liquid inlet at the upper part of the reaction kettle, and the acetylene gas inlet is connected with the gas inlet at the bottom of the reaction kettle.

Description

Device, system and method for preparing difluoroethane by continuous reaction
Technical Field
The invention relates to the technical field of chemical technology, in particular to a device, a system and a method for preparing difluoroethane by continuous reaction.
Background
1, 1-difluoroethane (R152 a) is an important novel environment-friendly refrigerant, is also an important chemical intermediate, has large market demand, is mainly provided with an acetylene route and a vinyl chloride route in the current industrial production of difluoroethane, wherein the reaction of acetylene and liquid phase anhydrous hydrofluoric acid to produce difluoroethane has the characteristics of mature process route, low operation difficulty and high conversion rate, is a domestic main stream process, and has the reaction principle as follows:
CH≡CH+HF→CH 2 CHF addition 1
CH 2 ＝CHF+HF→CH 3 CHF 2 (R152 a) addition 2
Acetylene gas enters liquid phase hydrogen fluoride, first one-step addition reaction is carried out under the action of a catalyst to generate intermediate product monofluoroethylene, the monofluoroethylene is continuously added with hydrogen fluoride to generate product 1, 1-difluoroethane, common catalysts comprise chlorides of metals such as mercury, aluminum, cadmium and the like, aluminum oxide, fluorosulfonic acid and the like, when the reaction is carried out in the reaction kettle, the catalyst (usually high-boiling point liquid) is added into the kettle in advance, the fed liquid hydrogen fluoride and gaseous acetylene are in countercurrent contact in the kettle, the mixture of the hydrogen fluoride, the catalyst and the acetylene gas is promoted by utilizing gas bubbling, the boiling point of the intermediate product fluoroethylene generated in the reaction is low, the intermediate product fluoroethane generated in the reaction is continuously bubbled in the liquid phase to generate second-step addition reaction, the intermediate product fluoroethylene which is not in the reaction, a small amount of hydrogen fluoride azeotroped with the difluoroethane are distilled out from the reaction kettle together, and the product difluoroethane and the byproduct fluoroethylene are obtained through a subsequent separation section.
In order to overcome the technical problem, two main improvement ideas are mainly provided at present, namely, a more efficient catalyst is sought, the reaction process is accelerated, the reaction time is further reduced, the vertical height of the reaction kettle is reduced, for example, patent CN 110028377A proposes that the conversion rate and the selectivity of the reaction can be remarkably improved by adding a cocatalyst containing nickel sulfonate in the catalysis process of fluorosulfonic acid, the reaction device is improved, the reaction efficiency is enhanced by strengthening longitudinal mixing, for example, patent CN 101417924A designs an external circulation and two-stage series reaction kettle process, the longitudinal back mixing of materials in the reaction kettle is enhanced by the external circulation of liquid materials, meanwhile, the contact time of gas phase and liquid phase is prolonged by two-stage series connection, the conversion rate of the reaction is improved, and patent CN 200610166228.3 designs the reaction kettle with a plurality of jackets and coils, the reaction heat can be removed in time, the uniformity of the temperature in the system is promoted, the problem of uneven longitudinal distribution of each component concentration caused by boiling point difference is avoided, the conversion rate and the safety of the reaction is improved, and in general, the research of a plurality of scholars and engineers is carried out, but the catalytic performance of the current catalyst can still meet the reaction requirements and the reaction process space is improved.
As described above, there is still a great room for improvement in the current process for producing difluoroethane by the liquid phase method of acetylene and hydrogen fluoride, and the main problems are focused on the following two aspects:
1. the gas-liquid mixing, mass transfer and heat transfer performance in the reaction kettle still needs to be improved
The existing improvement means such as external circulation, grading series connection and the like adopted for the reaction kettle can improve the mixing condition of materials of the reaction kettle to a certain extent, but because of the lack of crushing and turbulence between gas-liquid two phases, the reaction rate and the heat transfer rate are influenced by the fact that larger mass transfer resistance still exists between a gaseous reactant and a liquid reactant as well as between a catalyst, local overheating is easy to cause, the condition can not be improved in a targeted way due to the fact that a simple internal coil pipe and an external jacket are used for heat transfer, and the problem that the longitudinal distribution of different boiling point reactants is uneven due to temperature difference is also aggravated due to the fact that the local overheating causes potential safety hazards;
2. high energy consumption for product separation
Because the product difluoroethane can be azeotroped with hydrogen fluoride, a small amount of hydrogen fluoride is inevitably distilled out of the reaction kettle, the hydrogen fluoride in the outlet gas of the reaction kettle is absorbed by an absorbent in an absorption tower, and then the absorbent and the hydrogen fluoride are separated by rectification and are respectively recycled, the separation idea is common, and because the conversion rate of the current process is lower, more intermediate product fluoroethylene exists in the outlet gas, and the mixed gas after dehydrofluorination is further required to separate the product difluoroethane and the byproduct fluoroethylene, so that the subsequent separation working section equipment of the process is more, the energy consumption is high, and the space is further optimized.
SUMMARY OF THE PATENT FOR INVENTION
The invention aims to provide a device, a system and a method for preparing difluoroethane by continuous reaction, and in order to achieve the purposes, the invention provides the following technical scheme: the system comprises a hydrogen fluoride liquid inlet, an acetylene gas inlet, a reaction kettle, a first condenser, a circulating pump, a second condenser, an absorption device, a reboiler, a rectifying tower, a third condenser, a difluoroethane outlet and a lifting pump, wherein the hydrogen fluoride liquid inlet is connected with the upper liquid inlet of the reaction kettle, the acetylene gas inlet is connected with the lower liquid inlet of the reaction kettle, the lower liquid outlet of the reaction kettle is connected with the upper liquid inlet of the reactor through the circulating pump, the upper liquid outlet of the reaction kettle is connected with the first condenser gas inlet, the first condenser liquid outlet is connected with the lower liquid inlet of the reaction kettle, the upper liquid outlet of the absorption device is connected with the second condenser gas inlet, the lower liquid outlet of the absorption device is connected with the upper liquid inlet of the reaction kettle, the lower liquid outlet of the absorption device is connected with the middle liquid inlet of the rectifying tower, the lower liquid outlet of the reboiler is connected with the upper liquid inlet of the third condenser, the upper liquid inlet of the lower liquid inlet of the absorption device is connected with the upper liquid inlet of the rectifying tower, and the upper liquid inlet of the reaction kettle is connected with the upper liquid inlet of the rectifying tower; the reaction kettle comprises an upper tower body; a fresh hydrogen fluoride feed line; fresh hydrogen fluoride spray tray; a circulating liquid feed pipe and a spray tray; rotating the filler; a first jacket; a second jacket; a bubbling plate; the device comprises a motor, a rotating shaft and an acetylene gas feeding pipe, wherein the upper tower body is positioned at the top of a reaction kettle, a fresh hydrogen fluoride feeding pipe, a fresh hydrogen fluoride spraying disk, a circulating liquid feeding pipe and a spraying disk are fixedly arranged at the upper position of an inner cavity of the reaction kettle, a first jacket is fixedly arranged at the upper part of a shell of the reaction kettle, a second jacket is fixedly arranged at the lower part of the shell of the reaction kettle, a bubbling plate is fixedly arranged at the lower position of the inner cavity of the reaction kettle, the motor and the rotating shaft are positioned at the lower position of the bubbling plate, the motor and the rotating shaft are fixedly arranged in the reaction kettle, the acetylene gas feeding pipe is positioned at the bottom of the reaction kettle and connected with the bubbling plate, and a rotary filler is fixedly arranged on the rotating shaft; the absorption device comprises a motor and a rotating shaft; an absorbent feed tube; the rotary packing and the baffle plate are fixedly arranged at the upper position of the inner cavity of the equipment, the rotary packing is fixedly arranged at the bottom of the rotating rod, the baffle plate is fixedly arranged at the lower position of the inner cavity of the equipment, the absorbent feeding pipe is fixedly arranged inside the equipment, one end of the absorbent feeding pipe extends into the rotary packing, and the other end of the absorbent feeding pipe penetrates out of the equipment.
A process for the efficient production of difluoroethane comprising the steps of:
s1: the catalyst and the absorbent are added into the system in advance, the fresh hydrogen fluoride liquid and the acetylene gas are in countercurrent contact integrally in the reaction kettle, and the catalyst and the absorbent are crushed, mixed, reacted and subjected to heat transfer under the action of the rotary filler;
s2: gasifying the intermediate product fluoroethylene with low boiling point and the product difluoroethane in a reaction kettle, and evaporating out entrained part of hydrogen fluoride from the top of the reaction kettle; after rectifying at the top of the reaction kettle, introducing the mixed gas into the absorption device, enabling the mixed gas to be in countercurrent contact with the whole absorbent, extracting difluoroethane and fluoroethylene gas from the top of the absorption device, and extracting the absorbent and hydrogen fluoride from the bottom of the absorption device;
s3: the gas extracted from the top of the absorption device is separated and condensed to obtain a liquid product difluoroethane and a gaseous intermediate product fluoroethylene, and the fluoroethylene is returned to the bottom of the reaction kettle to continue the reaction; the absorbent and the hydrogen fluoride liquid are led into a rectifying tower for rectification, hydrogen fluoride is obtained from the top of the tower, and the absorbent is obtained from the bottom of the tower; the hydrogen fluoride liquid extracted from the top of the rectifying tower and the absorbent extracted from the bottom of the rectifying tower are respectively introduced into an upper jacket and a lower jacket for heating and heat removal.
Preferably, the catalyst comprises fluorosulfonic acid, chromium chloride, cadmium chloride, and tin chloride.
Preferably, the absorbent comprises amines such as aniline, ethylenediamine, etc., concentrated sulfuric acid, ethylene glycol.
Preferably, the volume fraction of the catalyst in the liquid in the reaction kettle is 5-50%.
Preferably, the molar flow ratio of acetylene to hydrogen fluoride of the feed is 1:2.1-8.
Preferably, the rotating speed of the rotary filler ranges from 500rpm to 2500rpm.
Preferably, the external circulation liquid amount of the reaction kettle is 3-50% of the total liquid amount in the kettle.
Compared with the prior art, the invention has the following beneficial effects:
(1) Reaction conversion and selectivity enhancement
As mentioned above, the reaction kettle provided by the invention can greatly promote the shearing, crushing and mixing of gas and liquid mutually, the reaction process is fully carried out, the conversion rate is improved within the same reaction time, the addition reaction of the intermediate product fluoroethylene can be rapidly carried out due to the uniform distribution of the catalyst in the kettle, and meanwhile, the gas-liquid contact time is prolonged when the liquid in the reaction kettle acts on the entrainment of bubbles, so that most fluoroethylene can be converted into difluoroethane before leaving the reaction kettle, and the reaction selectivity is improved;
(2) The energy consumption of the whole process is reduced
The energy consumption of the whole process is reduced mainly from two aspects: firstly, because the reaction in the reaction kettle is carried out efficiently, the content of fluoroethylene in the outlet gas is low, and the energy consumption for separating fluoroethylene and difluoroethane is low; secondly, the invention fully utilizes heat exchange among materials, thereby saving the public engineering energy consumption of the jacket of the reaction kettle;
(3) Device count and size reduction
Firstly, because the reactor used in the invention has high-efficiency mixing performance and longer gas-liquid contact time, the vertical height of the reaction kettle can be over 40 percent lower than that of the traditional slender reaction kettle under the same productivity, secondly, because the novel high-efficiency absorption device is used in the invention, the traditional absorption tower is omitted, thirdly, because the intermediate product fluoroethylene in the process can be mostly converted into the product difluoroethane, the fluoroethylene content can be ensured to be below 3 percent during final separation, the direct segregation separation is realized, and a rectifying tower for separating the product and byproducts is omitted;
(4) Process intrinsic safety enhancement
The device, the system and the method can strengthen intrinsic safety from two aspects of heat transfer and leakage prevention, in the aspect of heat transfer, as described above, heat transfer between materials and between the materials and the jacket can be rapidly carried out due to the good gas-liquid mixing state in the reaction kettle, and generated fluoroethylene and difluoroethane are rapidly gasified and transferred in the process of rapidly updating the gas-liquid surface, so that the danger caused by heat accumulation in the reaction kettle is avoided, and the leakage prevention aspect is realized: the hydrogen fluoride is extremely toxic, and the leakage result is serious, and the flow rate of the externally circulated feed liquid can be reduced by more than 80 percent compared with that of the traditional reaction kettle due to the good vertical mixing performance in the reaction kettle, so that the risk of externally circulated leakage is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a system diagram of the present invention for the continuous production of difluoroethane;
FIG. 2 is a structural diagram of a reaction vessel according to the present invention;
fig. 3 is a structural view of the absorption device of the present invention.
In the drawings, the list of components represented by the various numbers is as follows:
in fig. 1: 1. a hydrogen fluoride liquid inlet; 2. an acetylene gas inlet; 3. a reaction kettle; 4. a first condenser; 5. a circulation pump; 6. a second condenser; 7. an absorption device; 8. a reboiler; 9. a rectifying tower; 10. a third condenser; 11. a difluoroethane outlet; 12. a lift pump;
in fig. 2: 3-1, upper tower body; 3-2, a fresh hydrogen fluoride feeding pipe; 3-3, a fresh hydrogen fluoride spray tray; 3-4, a circulating liquid feeding pipe and a spraying disc; 3-5, rotating the filler; 3-6, jacket I; 3-7, a second jacket; 3-8, bubbling board; 3-9, a motor and a rotating shaft; 3-10, acetylene gas feeding pipe;
in fig. 3: 7-1, a motor and a rotating shaft; 7-2, an absorbent feeding pipe; 7-3, rotating the filler; 7-4, baffling the screen plate;
Detailed Description
The following description of the embodiments of the present invention will clearly and fully describe the technical solutions of the embodiments of the present invention in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments of the present invention. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the inventor, are within the scope of the invention.
The system comprises a hydrogen fluoride liquid inlet, an acetylene gas inlet, a reaction kettle, a first condenser, a circulating pump, a second condenser, an absorption device, a reboiler, a rectifying tower, a third condenser, a difluoroethane outlet and a lifting pump, wherein the hydrogen fluoride liquid inlet is connected with the liquid inlet at the upper part of the reaction kettle, the acetylene gas inlet is connected with the gas inlet at the bottom of the reaction kettle, the liquid outlet at the bottom of the reaction kettle is connected with the liquid inlet at the top of the reactor through the circulating pump, the gas outlet at the top of the reaction kettle is connected with the gas inlet of the first condenser, the liquid outlet at the top of the first condenser is connected with the liquid inlet at the top of the reaction kettle, the gas outlet at the top of the absorption device is connected with the gas inlet at the bottom of the absorption device, the liquid outlet at the bottom of the second condenser is connected with the gas inlet at the bottom of the reaction kettle, the liquid outlet at the bottom of the absorption device is connected with the liquid inlet at the middle part of the rectifying tower, the gas outlet at the bottom of the rectifying tower is connected with the gas inlet at the third condenser, the gas outlet at the top of the third condenser is divided into a reboiler, the top of the reboiler is connected with the liquid inlet at the bottom of the top of the rectifying tower, the top of the rectification tower is connected with the liquid inlet at the bottom of the top of the rectification tower through the upper part of the jacket and the liquid inlet of the top of the rectification device and the gas inlet is connected with the liquid inlet at the bottom of the top of the rectification device through the top of the inlet of the top of the rectification device.
A reaction kettle for continuously producing difluoroethane, which comprises an upper tower body; a fresh hydrogen fluoride feed line; fresh hydrogen fluoride spray tray; a circulating liquid feed pipe and a spray tray; rotating the filler; a first jacket; a second jacket; a bubbling plate; the upper tower body is positioned at the top of the reaction kettle, the fresh hydrogen fluoride feeding pipe, the fresh hydrogen fluoride spraying disk, the circulating liquid feeding pipe and the spraying disk are fixedly arranged at the upper part of the inner cavity of the reaction kettle, the first jacket is fixedly arranged at the upper part of the outer shell of the reaction kettle, the second jacket is fixedly arranged at the lower part of the outer shell of the reaction kettle, the bubbling plate is fixedly arranged at the lower part of the inner cavity of the reaction kettle, the motor and the rotating shaft are positioned at the lower part of the bubbling plate, the motor and the rotating shaft are fixedly arranged in the reaction kettle, the acetylene gas feeding pipe is positioned at the bottom of the kettle and connected with the bubbling plate, the rotary filler is fixedly arranged on the rotating shaft, under the action of the rotary filler, hydrogen fluoride and catalyst in the liquid phase are sheared and crushed at high speed, fully mixed and transferred, wherein the lower jacket two-way heating medium is used for quickly heating up the feed liquid to promote the reaction, the fluoroethylene generated by the reaction is quickly gasified and removed, because under the high-speed shearing of the rotary filler, the gas-liquid interface is quickly updated, the fluid is quickly turbulent, the heat transfer is quickly and fully performed, the upper jacket one-way cooling medium is used for removing the reaction heat, the heat transfer efficiency is high, the heat transfer is fully and quickly performed due to the high-speed shearing and turbulent of the fluid, the whole system temperature is maintained in a relatively stable state, acetylene gas and fluoroethylene gas are fully reacted with hydrogen fluoride through the multistage rotary filler, the filler is annular, the liquid in the inner cavity is thrown out through the filler under the centrifugal force, new liquid is sucked into the inner cavity area, in the high-speed entrainment process, the bubbles are entrained and whirled, the gas-rising track is more complex, the gas-liquid two-phase contact time is prolonged, through the action of multistage rotary packing, most of acetylene and fluoroethylene are converted into difluoroethane, the distilled gas is subjected to two-stage spraying action of circulating liquid and fresh feed hydrogen fluoride liquid, the high-boiling point catalyst is completely condensed and refluxed, and the outlet gas is rectified in a top tower plate and then refluxed with most of hydrogen fluoride, so that the difluoroethane with high purity is finally directly obtained, and a small amount of azeotropic hydrogen fluoride and byproduct fluoroethylene are contained.
An apparatus for efficiently absorbing hydrogen fluoride in difluoroethane and fluoroethylene, wherein the absorption device comprises a motor and a rotating shaft; an absorbent feed tube; the rotary packing and the baffle sieve plate are fixedly arranged at the upper position of the inner cavity of the equipment, the rotary packing is fixedly arranged at the bottom of the rotary rod, the baffle sieve plate is fixedly arranged at the lower position of the inner cavity of the equipment, the absorbent feeding pipe is fixedly arranged inside the equipment, one end of the absorbent feeding pipe extends to the inside of the rotary packing, the other end of the absorbent feeding pipe penetrates to the outside of the equipment, mixed gas is introduced into the absorption equipment from the bottom, firstly, the mixed gas is in cross-flow contact with the continuously flowing absorbent liquid film on the multi-layer baffle sieve plate, part of hydrogen fluoride is absorbed, the rest gas passes through the rotary packing, the absorption liquid is sprayed on the rotary packing through the feeding pipe and is sheared and dispersed into micron-sized liquid drops at high speed, the gas and the liquid are fully mixed and transferred, and finally the outlet gas hardly contains hydrogen fluoride.
A process for the efficient production of difluoroethane comprising the steps of:
s1: the catalyst and the absorbent are added into the system in advance, the fresh hydrogen fluoride liquid and the acetylene gas are in countercurrent contact integrally in the reaction kettle, and the catalyst and the absorbent are crushed, mixed, reacted and subjected to heat transfer under the action of the rotary filler;
s2: gasifying the intermediate product fluoroethylene with low boiling point and the product difluoroethane in a reaction kettle, and evaporating out entrained part of hydrogen fluoride from the top of the reaction kettle; after rectifying at the top of the reaction kettle, introducing the mixed gas into an absorption device, enabling the mixed gas to be in countercurrent contact with the whole absorbent, extracting difluoroethane and fluoroethylene gas from the top of the absorption device, and extracting the absorbent and hydrogen fluoride from the bottom of the absorption device;
s3: the gas extracted from the top of the absorption device is separated and condensed to obtain a liquid product difluoroethane and a gaseous intermediate product fluoroethylene, and the fluoroethylene is returned to the bottom of the reaction kettle to continue the reaction; the absorbent and the hydrogen fluoride liquid are led into a rectifying tower for rectification, hydrogen fluoride is obtained from the top of the tower, and the absorbent is obtained from the bottom of the tower; the hydrogen fluoride liquid extracted from the top of the rectifying tower and the absorbent extracted from the bottom of the rectifying tower are respectively introduced into an upper jacket and a lower jacket for heating and heat removal.
Specifically, the catalyst comprises fluorosulfonic acid, chromium chloride, cadmium chloride and tin chloride.
Specifically, the absorbent comprises amine substances such as aniline, ethylenediamine, etc., concentrated sulfuric acid, ethylene glycol.
Specifically, in the liquid in the reaction kettle, the volume fraction of the catalyst is 5-50%.
Specifically, the molar flow ratio of the acetylene to the hydrogen fluoride of the feed is 1:2.1-8.
Specifically, the rotating speed of the rotary filler ranges from 500rpm to 2500rpm.
Specifically, the external circulation liquid amount of the reaction kettle is 3-50% of the total liquid amount in the kettle.
Example 1:
the system, the device and the method are adopted for preparing the difluoroethane through continuous reaction, a fluorosulfonic acid catalyst is adopted, aniline is adopted as an absorbent, the volume fraction (alpha) of the fluorosulfonic acid is 15%, the molar flow ratio (beta) of the acetylene and the hydrogen fluoride fed into the reaction kettle is 1:2.1, the reaction temperature (T) is 40 ℃, the system pressure (P) is maintained at 0.1MPa, the reaction kettle adopts three-stage rotary fillers, each stage of rotary speed (R1) is 1000rpm, the rotary filler rotary speed (R2) in the absorption device is 1000rpm, the circulation liquid volume outside the reaction kettle is 5 percent (R) of the total liquid volume in the kettle, the reaction kettle is stably operated for 24 hours, the conversion rate (a) of the acetylene is 100%, the single-pass selectivity (b) of the difluoroethane is 98.1%, and the purity (c) of an outlet product is 99.95%.
Examples 2 to 15:
the procedure is the same as in example 1, except that the operating parameters are modified, and for simplicity, the parameters and units thereof appearing in example 1 are indicated by the letters indicated.
Examples 1 to 10 are among the technological parameters claimed by the invention, and the results of the examples show that the invention can obviously improve the conversion rate of raw materials and the purity of products, and meanwhile, the higher single-pass selectivity of the products means smaller separation and circulation energy consumption.
Wherein, some of the process operating parameters of examples 11-15 are outside the process parameters claimed in the present invention, which are comparative examples, and it can be reversely demonstrated that the effect achieved by the process of the present invention is obtained by the relative process and equipment improvements made by the present invention.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (6)

1. A system for continuous production of difluoroethane, characterized in that: the system comprises a hydrogen fluoride liquid inlet, an acetylene gas inlet, a reaction kettle, a first condenser, a circulating pump, a second condenser, an absorption device, a reboiler, a rectifying tower, a third condenser, a difluoroethane outlet and a lifting pump, wherein the hydrogen fluoride liquid inlet is connected with the liquid inlet at the upper part of the reaction kettle, the acetylene gas inlet is connected with the gas inlet at the bottom of the reaction kettle, the liquid outlet at the bottom of the reaction kettle is connected with the liquid inlet at the top of the reaction kettle through the circulating pump, the gas outlet at the top of the reaction kettle is connected with the gas inlet of the first condenser, the liquid outlet at the first condenser is connected with the liquid inlet at the top of the reaction kettle, the gas outlet at the top of the absorption device is connected with the gas inlet at the bottom of the second condenser, the liquid outlet at the second condenser is connected with the gas inlet at the bottom of the reaction kettle, the liquid outlet at the bottom of the absorption device is connected with the liquid inlet at the middle part of the rectifying tower, the gas outlet at the bottom of the rectifying tower is connected with the gas inlet at the third condenser through the circulating pump, the gas outlet at the bottom of the third condenser is connected with the liquid inlet at the bottom of the top of the rectifying tower through the top of the reboiler, the gas outlet at the bottom of the second condenser is connected with the liquid inlet at the top of the absorption device through the reboiler, the gas inlet of the top of the rectifying device is connected with the liquid inlet of the rectifying tower is connected with the liquid inlet at the top of the rectifying tower through the gas inlet; the reaction kettle comprises an upper tower body; a fresh hydrogen fluoride feed line; fresh hydrogen fluoride spray tray; a circulating liquid feed pipe and a spray tray; rotating the filler; a first jacket; a second jacket; a bubbling plate; the device comprises a motor, a rotating shaft and an acetylene gas feeding pipe, wherein the upper tower body is positioned at the top of a reaction kettle, a fresh hydrogen fluoride feeding pipe, a fresh hydrogen fluoride spraying disk, a circulating liquid feeding pipe and a spraying disk are fixedly arranged at the upper position of an inner cavity of the reaction kettle, a first jacket is fixedly arranged at the upper part of a shell of the reaction kettle, a second jacket is fixedly arranged at the lower part of the shell of the reaction kettle, a bubbling plate is fixedly arranged at the lower position of the inner cavity of the reaction kettle, the motor and the rotating shaft are positioned at the lower position of the bubbling plate, the motor and the rotating shaft are fixedly arranged in the reaction kettle, the acetylene gas feeding pipe is positioned at the bottom of the reaction kettle and connected with the bubbling plate, and a rotary filler is fixedly arranged on the rotating shaft; the absorption device comprises a motor and a rotating shaft; an absorbent feed tube; the rotary packing and the baffle plate are fixedly arranged at the upper position of the inner cavity of the equipment, the rotary packing is fixedly arranged at the bottom of the rotating rod, the baffle plate is fixedly arranged at the lower position of the inner cavity of the equipment, the absorbent feeding pipe is fixedly arranged inside the equipment, one end of the absorbent feeding pipe extends into the rotary packing, and the other end of the absorbent feeding pipe penetrates out of the equipment.
2. A method of producing difluoroethane using the system of claim 1, wherein: the method comprises the following steps:
s1: the catalyst and the absorbent are added into the system in advance, the fresh hydrogen fluoride liquid and the acetylene gas are in countercurrent contact integrally in the reaction kettle, and the catalyst and the absorbent are crushed, mixed, reacted and subjected to heat transfer under the action of the rotary filler;
s2: gasifying the intermediate product fluoroethylene with low boiling point and the product difluoroethane in a reaction kettle, and evaporating out entrained part of hydrogen fluoride from the top of the reaction kettle; after rectifying at the top of the reaction kettle, introducing the mixed gas into the absorption device, enabling the mixed gas to be in countercurrent contact with the whole absorbent, extracting difluoroethane and fluoroethylene gas from the top of the absorption device, and extracting the absorbent and hydrogen fluoride from the bottom of the absorption device;
s3: the gas extracted from the top of the absorption device is separated and condensed to obtain a liquid product difluoroethane and a gaseous intermediate product fluoroethylene, and the fluoroethylene is returned to the bottom of the reaction kettle to continue the reaction; the absorbent and the hydrogen fluoride liquid are led into a rectifying tower for rectification, hydrogen fluoride is obtained from the top of the tower, and the absorbent is obtained from the bottom of the tower; the hydrogen fluoride liquid extracted from the top of the rectifying tower and the absorbent extracted from the bottom of the rectifying tower are respectively introduced into an upper jacket and a lower jacket for heating and heat removal.
3. A process for producing difluoroethane as claimed in claim 2, wherein: in the liquid in the reaction kettle, the volume fraction of the catalyst is 5-50%.
4. A process for producing difluoroethane as claimed in claim 2, wherein: the molar flow ratio of the acetylene to the hydrogen fluoride of the feed is 1:2.1-8.
5. A process for producing difluoroethane as claimed in claim 2, wherein: the rotating speed of the rotary filler ranges from 500rpm to 2500rpm.
6. A process for producing difluoroethane as claimed in claim 2, wherein: the external circulation liquid amount of the reaction kettle is 3-50% of the total liquid amount in the kettle.
CN202210743715.0A 2022-06-28 2022-06-28 Device, system and method for preparing difluoroethane by continuous reaction Active CN115106043B (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112705125A (en) * 2020-11-27 2021-04-27 北京化工大学 System, method and reaction device for preparing trifluoroethane by continuous reaction

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112705125A (en) * 2020-11-27 2021-04-27 北京化工大学 System, method and reaction device for preparing trifluoroethane by continuous reaction

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