A method for recovering and utilizing ammonia in the synthesis of acetonitrile from acetic acid and ammonia

Abstract

The present application belongs to the technical field of waste gas treatment and ammonia recovery, and particularly relates to a method for ammonia recovery and utilization in the process of synthesizing acetonitrile from ammonium acetate, which uses an extractant to absorb ammonia, acetonitrile and acetone in tail gas generated in the process of synthesizing acetonitrile from ammonium acetate, and to remove carbon dioxide; the mixed liquid after extraction absorption is punched into a pressurized ammonia distillation tower for ammonia distillation, ammonia in the mixed liquid is vaporized after being heated and is discharged from the top of the tower to be condensed into liquid ammonia product; the residual kettle liquid after recovery of ammonia gas in the pressurized ammonia distillation tower is punched into an atmospheric distillation tower by a pump for atmospheric distillation; acetonitrile crude product is taken out from the side line of the atmospheric distillation tower; acetone is discharged from the top of the atmospheric distillation tower, and the liquid taken out from the kettle is the extractant, which is returned to the extraction absorption tower to continue to absorb tail gas and is reused; the present application realizes recovery and utilization of tail gas in the process of synthesizing acetonitrile from ammonium acetate by adopting the extraction absorption, pressurized ammonia distillation and atmospheric distillation process, has high ammonia recovery rate, simple overall process, simple operation, low cost, easy automation and wide market prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste gas treatment and ammonia recovery, and particularly relates to a method for ammonia recovery and utilization in acetic acid ammoniation synthesis of acetonitrile. BACKGROUND

[0002] Acetonitrile is a widely used solvent, which can be used as a separation solvent for hydrocarbon oil, can separate butadiene from C4 hydrocarbon, can separate propylene, isoprene and methyl acetylene from hydrocarbon fractions, and can extract and separate fatty acids from vegetable oil and fish liver oil. Acetonitrile is also an important organic intermediate, which can be used to synthesize various medicines and pesticides. In medicine, it is used to synthesize a series of important medicine intermediates such as vitamin B1, methotrexate, chloroquine, adenine and dextromethorphan. In pesticides, it is used to synthesize pyrethroid insecticides and pesticide intermediates such as ethoxyfen. In addition to the above applications, acetonitrile can also be used as an organic synthesis raw material, a component of a catalyst or a transition metal complex catalyst, used in vinyl coatings, alcohol denaturants, and has many uses in fabric dyeing, lighting, perfume manufacturing and photosensitive material manufacturing.

[0003] The current industrial synthesis method of acetonitrile is acetic acid ammoniation method. The acetic acid ammoniation method has fewer impurities in the product, the product is pure, the purity is high, and the separation process is simple. However, a large amount of waste gas containing ammonia, acetonitrile, acetone and carbon dioxide is generated in the process of synthesizing acetonitrile, and the environmental protection problem becomes a bottleneck problem of acetonitrile production by acetic acid ammoniation, which seriously restricts the production of acetonitrile. The waste of excess ammonia causes the high production cost of acetonitrile, and reduces the market competitiveness of acetonitrile.

[0004] Some related patents mention that water or sulfuric acid can be used to spray and absorb ammonia. When water is used for spraying, part of the acetonitrile will enter the ammonia water during the later separation, resulting in poor quality of the ammonia water, high treatment difficulty, waste of raw materials, and generation of heat in the absorption process, part of the organic gas volatilizes into the atmosphere, causing pollution. The use of sulfuric acid for spraying requires high equipment requirements due to the strong corrosion of sulfuric acid. In addition, the reaction produces ammonium sulfate solution. Due to the presence of ammonia and nitrogen components in the solution and the high salt content, the solution must be distilled and desalted first, then treated by deamination, and then biologically treated after deamination is completed, so as to reach the sewage discharge standard, resulting in high difficulty in sewage treatment. These two methods have their own shortcomings, and satisfactory research results have not been achieved, so it is urgent to develop a method for ammonia recovery and utilization in the process of acetic acid ammoniation synthesis of acetonitrile. SUMMARY

[0005] The purpose of the present application is to overcome the problems of poor safety, serious equipment corrosion, high production cost and difficult environmental protection treatment in the prior art, and to develop a method for ammonia recovery and utilization in the process of acetic acid ammoniation synthesis of acetonitrile.

[0006] To achieve the above object, the application provides a method for recycling ammonia in the synthesis of acetonitrile from acetamide, comprising the following steps:

[0007] (1) extraction absorption: the tail gas generated in the synthesis of acetonitrile from acetamide is introduced into an extraction agent, and the extraction agent is used to absorb ammonia, acetonitrile and acetone in the tail gas and to remove carbon dioxide;

[0008] (2) pressurized ammonia distillation: the mixed liquid after extraction absorption is introduced into a pressurized ammonia distillation tower for ammonia distillation, and the ammonia in the mixed liquid is vaporized by heating and discharged from the top of the tower to be condensed into liquid ammonia products, part of which is refluxed and part of which is gasified by a gasifier and then returned to a reaction kettle for producing acetonitrile, thereby being recycled; the residual kettle liquid contains a small amount of acetonitrile and a large amount of extraction agent; the mass content of ammonia in the liquid ammonia products is 99.9%;

[0009] (3) normal pressure rectification: the residual kettle liquid after recovery of ammonia gas is introduced into a normal pressure rectification tower by a pump for normal pressure rectification, and acetonitrile crude products are taken out from the side line, the acetonitrile crude products taken out are sampled and detected to contain many impurities, and high-content acetonitrile finished products are obtained after further rectification and purification; the gas phase discharged from the top of the normal pressure rectification tower is condensed into liquid phase by a condenser, and the mass content of acetone in the liquid phase is 85-95%; the liquid taken out from the kettle of the normal pressure rectification tower is the extraction agent, which is returned to the extraction absorption tower to continue absorbing the tail gas, thereby being recycled; when the content of the extraction agent in the liquid taken out from the kettle of the normal pressure rectification tower is lower than 80%, fresh extraction agent is supplemented in time; the mass content of acetonitrile in the acetonitrile crude products is 80-90%.

[0010] Specifically, the extraction agent in step 1 is ethanolamine or N-methyl pyrrolidone (NMP), and preferably is ethanolamine; the flow rate of the extraction agent is 1.5-6.5 cubic meters / hour.

[0011] Specifically, the operation temperature of the extraction absorption tower in step 1 is 40-70℃, and preferably is 55-65℃; the flow rate of the tail gas is 1.0-3.0 m / s.

[0012] Specifically, the operation pressure of the pressurized ammonia distillation tower in step 2 is 1.0-2.0 Mpa, and preferably is 1.3-1.8 Mpa; the feed flow rate is 3-8 cubic meters / hour.

[0013] Specifically, the operation temperature of the pressurized ammonia distillation tower in step 2 is 115-135℃.

[0014] Specifically, the liquid ammonia reflux ratio of the pressurized ammonia distillation tower in step 2 is 5-10:1.

[0015] Specifically, the operation temperature of the normal pressure rectification tower in step 3 is 120-150℃, and the feed flow rate is 2.8-7.8 cubic meters / hour.

[0016] Specifically, the reflux ratio of the atmospheric rectification tower in step 3 is 5-10:1.

[0017] The content in the present application is the mass content.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] (1) The extractant is used to absorb the tail gas, selectively absorb ammonia and acetonitrile, and discharge carbon dioxide to prevent equipment blockage;

[0020] (2) The pressurized ammonia distillation is used, which improves the concentration of recovered liquid ammonia compared with atmospheric ammonia distillation, and reduces the water content in liquid ammonia by 75%;

[0021] (3) The extractant can be reused, which not only saves raw material cost, but also reduces the generation of sewage and protects the ecological environment compared with the conventional process.

[0022] In summary, the present application adopts the extraction absorption, pressurized ammonia distillation and atmospheric rectification process to realize the recycling of tail gas in the process of synthesizing acetonitrile from ammonium acetate, has high ammonia recovery rate, simple overall process, simple operation, low cost, easy automation and wide market prospect. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The present application relates to the process flow principle diagram of the method for recycling ammonia in the process of synthesizing acetonitrile from ammonium acetate. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below by specific examples and in combination with the drawings.

[0025] Example 1

[0026] The embodiment relates to a method for recycling ammonia in an acetic acid ammonia synthesis process of acetonitrile, which is completed through an ammonia recycling system, the ammonia recycling system comprises an extraction absorption tower 1, a pressurized ammonia distillation tower 2 and an atmospheric distillation tower 3, the extraction absorption tower 1 is used for extracting ammonia and acetonitrile in tail gas of an acetic acid ammonia synthesis reactor, is provided with an acetic acid ammonia synthesis reactor tail gas inlet end, an extractant inlet end and an extraction mixed liquid outlet end, the extraction mixed liquid outlet end is connected with a material inlet end of the pressurized ammonia distillation tower 2, the top of the pressurized ammonia distillation tower 2 is used for outputting vaporized ammonia, the vaporized ammonia is condensed into liquid ammonia products by an ammonia condenser 5 and enters an ammonia distillation reflux tank 6, part of the liquid ammonia products is refluxed to the pressurized ammonia distillation tower through a pump 4, and part of the liquid ammonia products is pumped to a liquid ammonia collecting tank and is sent to the acetic acid ammonia synthesis reactor through a vaporizer; the bottom of the pressurized ammonia distillation tower 2 is used for outputting extraction mixed liquid after ammonia distillation; the bottom outlet end of the pressurized ammonia distillation tower 2 is connected with a material inlet end of the atmospheric distillation tower 3; the atmospheric distillation tower 3 is used for rectifying the extraction mixed liquid after ammonia distillation to recover the extractant, acetone in the extraction mixed liquid is vaporized by heating and flows out from the top of the tower, is condensed after passing through a condenser 9 and enters a recovery reflux tank 10, part of the acetone is refluxed to the atmospheric distillation tower 3 through a pump, and the other part of the acetone is pumped to a burning furnace for burning treatment; a side line of the atmospheric distillation tower is used for extracting acetonitrile crude products; the extraction mixed liquid is rectified to be the extractant, flows out from the bottom of the tower and is recovered, and the extractant is pumped back to the extraction absorption tower by the pump 4 for recycling.

[0027] The acetonitrile crude products extracted from the side line of the atmospheric distillation tower 3 are condensed after passing through a condenser 13 and enter an acetonitrile recovery tank 15, the content of the acetonitrile crude products is detected, the acetonitrile crude products in the acetonitrile recovery tank 15 are pumped into an acetonitrile rectification tower for further purification, and acetonitrile products obtained are pumped into an acetonitrile product tank.

[0028] The method for recycling ammonia in the acetic acid ammonia synthesis process of acetonitrile includes the following specific steps:

[0029] The tail gas from the acetic acid ammonia reactor is introduced into the packed extraction absorption tower 1 at a flow rate of 2.0 m / s, the operating temperature of the extraction absorption tower is maintained at 40°C, ethanolamine is used as the extractant for extraction absorption, the ethanolamine liquid is introduced into the extraction absorption tower from the top, the flow rate is 1.5 cubic meters / hour; in the extraction tower, the ethanolamine liquid at the top falls into the wire mesh packing through the liquid collector and the liquid redistributor, and is absorbed by the tail gas going upward in the packing; the carbon dioxide is not soluble in the extractant, and can be removed by increasing the temperature, thereby removing the carbon dioxide and preventing the equipment from being blocked; the carbon dioxide gas is discharged from the top of the tower, the mixed liquid after extraction flows out from the bottom of the extraction absorption tower 1, and the mass content of ammonia in the mixed liquid after extraction at this time is 14.3%, and the mass content of carbon dioxide is 2%; the mixed liquid after extraction flowing out from the bottom of the extraction absorption tower is pumped into the pressurized ammonia distillation tower 2 by the pump 4, the mixed liquid after extraction is heated to vaporize the ammonia dissolved in the liquid, the operating pressure of the pressurized ammonia distillation tower is maintained at 1.3 MPa, the operating temperature is 120°C, and the feed flow rate is about 5 cubic meters / hour; the vaporized ammonia is distilled from the top of the tower, is condensed by the ammonia condenser 5, and then enters the ammonia distillation reflux tank 6; part of the liquid ammonia product in the ammonia distillation reflux tank 6 is refluxed to the pressurized ammonia distillation tower by the pump, and the reflux ratio is controlled to be 5-10:1; part of the liquid ammonia product enters the liquid ammonia collection tank 17, and the ammonia content in the liquid ammonia product in the liquid ammonia collection tank 17 is 99.9% after gasification, and there is a small amount of acetone; the remaining liquid after ammonia vaporization of the pressurized ammonia distillation tower 2 flows out from the tower bottom, is pumped into the atmospheric distillation tower 3 by the pump 4, and the ethanolamine is recovered; the operating temperature of the atmospheric distillation tower is 125°C, the feed flow rate is 5 cubic meters / hour, the gas phase distilled from the top of the tower is condensed by the recovery tower top condenser 9 and enters the recovery tower reflux tank 10, the mass content of acetone in the liquid phase product in the recovery tower reflux tank is 90.1%, part of the product in the recovery tower reflux tank 10 is refluxed to the atmospheric distillation tower by the pump 4, and part of the product is taken out and incinerated, and the reflux ratio is controlled to be 5-10:1; the gaseous acetonitrile crude product is taken out from the side line of the atmospheric distillation tower 3, is condensed by the recovery tower acetonitrile take-out condenser 13 to obtain the acetonitrile crude product, the acetonitrile content in the acetonitrile crude product is 84.8%, and the acetonitrile crude product is pumped into the acetonitrile distillation tower for purification, and then is pumped into the acetonitrile product tank after being qualified; the mass content of the extractant ethanolamine in the liquid taken out from the tower bottom of the atmospheric distillation tower 3 is 98%, and the extractant is pumped back to the extraction absorption tower by the pump 4 for repeated use.

[0030] Example 2

[0031] The embodiment relates to a method for recycling ammonia in an acetic acid ammoniation synthesis acetonitrile process, which is completed through the ammonia recycling system in embodiment 1, and specific steps are as follows: tail gas from an acetic acid ammoniation reactor is introduced into an extraction absorption tower 1 at a flow rate of 3.0 m / s, the operation temperature of the extraction absorption tower is maintained at 55 DEG C, ethanolamine is used as an extractant to perform extraction absorption at a flow rate of 4 cubic meters / hour; in the extraction tower, ethanolamine liquid at the top is dropped into wire gauze packing through a liquid collector and a liquid redistributor, and is absorbed by contacting with the tail gas going upwards in the packing; carbon dioxide is not soluble in the extractant, and can be removed by increasing the temperature, so that the purposes of removing carbon dioxide and preventing equipment from being blocked are achieved; carbon dioxide gas is discharged from the top of the extraction absorption tower, and the mixed liquid after extraction flows out from the bottom of the extraction absorption tower 1, sampling detection of the ammonia mass content in the mixed liquid after extraction at this time shows that the ammonia mass content is 15.8%, and no carbon dioxide is detected, which indicates that the carbon dioxide is completely discharged from the top of the tower; the mixed liquid after extraction flowing out from the bottom of the extraction absorption tower is pumped into a pressurized ammonia distillation tower, the operation pressure of the pressurized ammonia distillation kettle is maintained at 1.5 Mpa, the operation temperature is 125 DEG C, the feeding flow rate is about 4 cubic meters / hour, ammonia gas distilled from the top of the tower is condensed and then introduced into an ammonia distillation reflux tank 6, part of liquid ammonia products in the ammonia distillation reflux tank 6 is refluxed to the pressurized ammonia distillation tower, and part of the liquid ammonia products is introduced into a liquid ammonia collecting tank 17, the reflux ratio is controlled to be 5-10:1, the ammonia content of the liquid ammonia products in the liquid ammonia collecting tank 17 is 99.9% after sampling detection, the liquid ammonia products are gasified and then pumped back to the acetic acid ammoniation reactor for reuse, the liquid phase is condensed by using the gaseous phase distilled from the top of the tower, sampling detection shows that the mass content of the acetone in the liquid phase is 90.3%, part of the liquid phase acetone is refluxed, and part of the liquid phase acetone is sampled out and introduced into a burning furnace for burning treatment, and the reflux ratio is controlled to be 5-10:1; acetonitrile crude products are sampled out from a side line of the atmospheric distillation tower 3, sampling detection shows that the acetonitrile content in the acetonitrile crude products is 87.1%, the acetonitrile crude products are pumped into an acetonitrile distillation tower, and then are pumped into an acetonitrile product tank after being purified; the content of the extractant ethanolamine in the liquid sampled out from the bottom of the atmospheric distillation tower is 98%, and the extractant is pumped back to the extraction absorption tower by using a pump 4 for reuse.

[0032] Embodiment 3

[0033] The embodiment relates to a method for recycling ammonia in an acetic acid ammoniation synthesis acetonitrile process, which is completed through the ammonia recycling system in embodiment 1, and specific steps are as follows: tail gas from an acetic acid ammoniation reactor is introduced into an extraction absorption tower 1 at a flow rate of 1.0 m / s, the operation temperature of the extraction absorption tower is maintained at 55 DEG C, ethanolamine is used as an extractant for extraction absorption, and the flow rate is 4 cubic meters / hour; in the extraction tower, ethanolamine liquid at the top falls into wire gauze packing through a liquid collector and a liquid redistributor, and is absorbed by contacting with the tail gas going upwards; carbon dioxide is not soluble in the extractant, and can be removed by increasing the temperature, so that the purpose of removing carbon dioxide and preventing equipment from being blocked is achieved; carbon dioxide gas is discharged from the top of the extraction absorption tower, and the mixed liquid after extraction flows out from the bottom of the extraction absorption tower 1, sampling detection of ammonia content in the mixed liquid after extraction shows that the ammonia content is 15.6%, and no carbon dioxide is detected, which indicates that the carbon dioxide is completely discharged from the top; the mixed liquid after extraction is introduced into a pressurized ammonia distillation tower 2, the operation pressure of the pressurized ammonia distillation tower is maintained at 1.3 Mpa, the operation temperature is 125 DEG C, and the feeding flow rate is about 6 cubic meters / hour; ammonia gas distilled from the top of the pressurized ammonia distillation tower is condensed and then introduced into an ammonia distillation reflux tank 6, part of liquid ammonia products in the ammonia distillation reflux tank 6 is refluxed to the pressurized ammonia distillation tower, and part of the liquid ammonia products is introduced into a liquid ammonia collecting tank 17, the reflux ratio is controlled to be 5-10:1, the liquid ammonia products in the liquid ammonia collecting tank 17 are gasified and then introduced into the acetic acid ammoniation reactor again, detection of ammonia content in the liquid ammonia products shows that the ammonia content is 99.9%, and there is a small amount of acetone; the kettle liquid of the pressurized ammonia distillation tower is pumped into an atmospheric distillation tower 3 to recover ethanolamine, the operation temperature of the atmospheric distillation tower is maintained at 130 DEG C, the feeding flow rate is 4 cubic meters / hour, the gas phase evaporated from the top of the atmospheric distillation tower is condensed into liquid phase, detection of the mass content of acetone in the liquid phase shows that the mass content of acetone is 91.4%, part of the liquid phase acetone is refluxed, and part of the liquid phase acetone is taken out and introduced into a burning furnace for burning treatment, and the reflux ratio is controlled to be 5-10:1; acetonitrile crude products are taken out from the side line of the atmospheric distillation tower, the acetonitrile content in the acetonitrile crude products is 86.9%, the acetonitrile crude products are pumped into an acetonitrile distillation tower, and after being purified, the acetonitrile crude products are pumped into an acetonitrile product tank; the content of the extractant ethanolamine in the liquid taken out from the kettle of the atmospheric distillation tower is 98%, and the extractant is pumped back into the extraction absorption tower for recycling by a pump 4.

[0034] Embodiment 4

[0035] The embodiment relates to a method for recycling ammonia in an acetic acid ammonia synthesis process, which is completed by the ammonia recycling system in embodiment 1, and specific steps are as follows: tail gas from an acetic acid ammonia reaction kettle is introduced into an extraction absorption tower 1 at a flow rate of 2.0 m / s, the operation temperature of the extraction absorption tower is maintained at 60 DEG C, ethanolamine is used as an extractant for extraction absorption, and the flow rate is 3 cubic meters / hour; in the extraction tower, ethanolamine liquid at the top is dropped into wire gauze packing through a liquid collector and a liquid redistributor, and is absorbed by contacting with the tail gas going upwards in the packing; carbon dioxide is insoluble in the extractant, and can be removed by increasing the temperature, so that the purpose of removing carbon dioxide and preventing equipment from being blocked is achieved; carbon dioxide is discharged at the top of the extraction absorption tower, and the mixed liquid after extraction flows out from the bottom of the extraction absorption tower 1, and the ammonia content in the mixed liquid after extraction is 14.4% at this time, and no carbon dioxide is detected, which indicates that the carbon dioxide is completely discharged at the top; the mixed liquid after extraction is introduced into a pressurized ammonia distillation tower, the operation pressure of the pressurized ammonia distillation tower is maintained at 1.5 MPa, the operation temperature is 130 DEG C, the feed flow rate is about 5 cubic meters / hour, ammonia gas distilled at the top is condensed and then introduced into an ammonia distillation reflux tank 6, part of liquid ammonia products in the ammonia distillation reflux tank 6 is refluxed to the pressurized ammonia distillation tower, and part of the liquid ammonia products is introduced into a liquid ammonia collecting tank 17, the reflux ratio is controlled to be 5-10:1, the liquid ammonia products in the liquid ammonia collecting tank 17 are gasified and then introduced into the acetic acid ammonia reaction kettle for reuse, and the ammonia content in the liquid ammonia products is 99.9%; the kettle liquid of the pressurized ammonia distillation tower is pumped into a normal-pressure rectifying tower 3 to recover ethanolamine, the temperature of the normal-pressure rectifying tower is maintained at 135 DEG C, the feed flow rate is 7 cubic meters / hour, the gas phase evaporated at the top is condensed into liquid phase, the mass content of acetone in the liquid phase is 92.8%, part of the condensed liquid phase is refluxed, and part of the condensed liquid phase is taken out and introduced into a burning furnace for burning treatment, and the reflux ratio is controlled to be 5-10:1; crude acetonitrile is taken out from the side line of the normal-pressure rectifying tower, the acetonitrile content in the crude acetonitrile is 87.7%, the crude acetonitrile is pumped into an acetonitrile rectifying tower, is purified, and is then introduced into an acetonitrile product tank; the content of the extractant ethanolamine in the liquid taken out from the kettle of the normal-pressure rectifying tower is 98%, and the extractant is pumped back to the extraction absorption tower for reuse.

[0036] Embodiment 5

[0037] The embodiment relates to a method for recycling ammonia in an acetic acid ammonia synthesis acetonitrile process, which is completed through the ammonia recycling system in embodiment 1, and specific steps are as follows: tail gas from an acetic acid ammonia reaction kettle is introduced into an extraction absorption tower 1 at a flow rate of 2.0 m / s, the operation temperature of the extraction absorption tower is maintained at 55 DEG C, ethanolamine is used as an extractant for extraction absorption, and the flow rate is 5 cubic meters / hour; in the extraction tower, ethanolamine liquid on the top falls into wire gauze packing through a liquid collector and a liquid redistributor, and is absorbed by contacting tail gas going upwards in the packing; carbon dioxide is not soluble in the extractant, and can be removed by increasing the temperature, so that the purposes of removing carbon dioxide and preventing equipment blockage are achieved; carbon dioxide is discharged from the top of the extraction absorption tower, and mixed liquid after extraction flows out from the bottom of the extraction absorption tower 1, sampling detection shows that the ammonia content in the mixed liquid after extraction is 16.1%, and no carbon dioxide is detected, which indicates that the carbon dioxide is completely discharged from the top; the mixed liquid after extraction is introduced into a pressurized ammonia distillation tower, the operation pressure of the pressurized ammonia distillation kettle is maintained at 1.5 Mpa, the operation temperature is 130 DEG C, the feed flow rate is about 6 cubic meters / hour, ammonia gas distilled from the top is condensed and then introduced into an ammonia distillation reflux tank 6, part of liquid ammonia products in the ammonia distillation reflux tank 6 is refluxed to the pressurized ammonia distillation tower, and part of the liquid ammonia products is introduced into a liquid ammonia collecting tank 17, the reflux ratio is controlled to be 5-10:1, the ammonia content in the liquid ammonia products after gasification and then being introduced into the acetic acid ammonia reaction kettle for recycling is 99.9%; kettle liquid of the pressurized ammonia distillation tower is pumped into an atmospheric pressure rectifying tower 3 to recover ethanolamine, the operation temperature of the atmospheric pressure rectifying tower is maintained at 150 DEG C, the feed flow rate is 5 cubic meters / hour, gas phase evaporated from the top is condensed into liquid phase, the mass content of acetone in the liquid phase is 93.7%, part of the liquid phase is refluxed, and part of the liquid phase is introduced into a burning furnace for burning treatment, and the reflux ratio is controlled to be 5-10:1; acetonitrile crude products are collected from a side line of the atmospheric pressure rectifying tower, the acetonitrile content in the acetonitrile crude products is 88.2%, the acetonitrile crude products are pumped into an acetonitrile rectifying tower for purification, and then are introduced into an acetonitrile product tank after being qualified; the content of the extractant ethanolamine in liquid collected from the kettle of the atmospheric pressure rectifying tower is 98%, and the extractant is pumped back to the extraction absorption tower for recycling.

Claims

1. A method for the recovery and utilization of ammonia in the synthesis of acetonitrile from acetic acid and ammonia, characterized in that, The specific steps include: (1) extraction absorption: the tail gas generated in the process of synthesizing acetonitrile from ammonium acetate is introduced into an extractant, and the extractant is used to absorb ammonia, acetonitrile and acetone in the tail gas; the extractant is ethanolamine; (2) pressurized ammonia distillation: the mixed liquid after extraction absorption is pumped into a pressurized ammonia distillation tower for ammonia distillation, the ammonia in the mixed liquid is vaporized after being heated and discharged from the top of the tower to be condensed into liquid ammonia product, part of the liquid ammonia product is refluxed, and part of the liquid ammonia product is gasified by a gasifier and then returned to the ammonium acetate reaction kettle for repeated use; the residual kettle liquid after recovering ammonia gas by the pressurized ammonia distillation tower is pumped into an atmospheric rectification tower for atmospheric rectification; (3) atmospheric rectification: the acetonitrile crude product is taken out from the side line of the atmospheric rectification tower; the gaseous phase acetone distilled from the top of the atmospheric rectification tower is condensed, part of which is refluxed, and part of which is introduced into a incinerator for incineration treatment; the liquid taken out from the bottom of the atmospheric rectification tower is the extractant, which is returned to the extraction absorption tower for absorbing the tail gas and repeated use.

2. The method for ammonia recovery and utilization in the synthesis of acetonitrile from acetic acid according to claim 1, characterized in that, The operating temperature of the extraction absorption tower in step (1) is 40-70℃.

3. The process of claim 2, wherein the ammonia is recovered from the acetic acid ammoniation synthesis of acetonitrile, characterized by, The operating temperature of the extraction absorption tower in step (1) is 55-65℃.

4. The method of claim 1, wherein the ammonia is recovered from the acetic acid ammoniation synthesis of acetonitrile process by, The operating pressure of the pressurized ammonia distillation tower in step (2) is 1.0-2.0Mpa, and the operating temperature is 115-135℃; the liquid ammonia reflux ratio is 5-10:1; the mass content of ammonia in the liquid ammonia product is 99.9%.

5. The method of claim 4, wherein the ammonia is recovered from the acetic acid ammoniation synthesis of acetonitrile process by, The operating pressure of the pressurized ammonia distillation tower in step (2) is 1.3-1.8Mpa.

6. The method for ammonia recovery and utilization in the synthesis of acetonitrile from acetic acid according to claim 1, characterized in that, The operating temperature of the atmospheric rectification tower in step 3 is 120-150℃; the acetone reflux ratio is 5-10:

1.

7. The method of claim 1, wherein the ammonia is recovered from the acetic acid ammoniation synthesis of acetonitrile process by, The gaseous phase condensed after being distilled from the top of the atmospheric rectification tower in step (3) is liquid phase acetone, the mass content of acetone in the liquid phase is 85-95%, and the mass content of acetonitrile in the acetonitrile crude product taken out from the side line is 80-90%.

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