CN212335081U - Distillation apparatus for purifying (meth) acrylonitrile or hydrogen cyanide - Google Patents
Distillation apparatus for purifying (meth) acrylonitrile or hydrogen cyanide Download PDFInfo
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- CN212335081U CN212335081U CN202020105180.0U CN202020105180U CN212335081U CN 212335081 U CN212335081 U CN 212335081U CN 202020105180 U CN202020105180 U CN 202020105180U CN 212335081 U CN212335081 U CN 212335081U
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- condenser
- distillation column
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/32—Separation; Purification; Stabilisation; Use of additives
- C07C253/34—Separation; Purification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C3/00—Cyanogen; Compounds thereof
- C01C3/02—Preparation, separation or purification of hydrogen cyanide
- C01C3/0208—Preparation in gaseous phase
- C01C3/0212—Preparation in gaseous phase from hydrocarbons and ammonia in the presence of oxygen, e.g. the Andrussow-process
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C3/00—Cyanogen; Compounds thereof
- C01C3/02—Preparation, separation or purification of hydrogen cyanide
- C01C3/0295—Purification
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/24—Preparation of carboxylic acid nitriles by ammoxidation of hydrocarbons or substituted hydrocarbons
- C07C253/26—Preparation of carboxylic acid nitriles by ammoxidation of hydrocarbons or substituted hydrocarbons containing carbon-to-carbon multiple bonds, e.g. unsaturated aldehydes
Abstract
The present application provides a purification apparatus for (meth) acrylonitrile, which can effectively reflux, suppress leakage of hydrogen cyanide, and suppress clogging due to tray contamination of a dehydrocyanation dehydration column, thereby enabling stable operation for a long period of time, even without using a pump or the like in a purification process for (meth) acrylonitrile or hydrogen cyanide. The distillation apparatus comprises a distillation column and a condenser connected to the distillation column, and purifies (meth) acrylonitrile or hydrogen cyanide from a solution containing (meth) acrylonitrile, hydrogen cyanide, and water, wherein the distillation apparatus comprises a reflux pipe for refluxing a condensate to the distillation column from an outlet of the condenser, one end of the reflux pipe is connected to an outlet of the condenser, the other end of the reflux pipe is connected to an upper portion of the distillation column, and an outlet of the condenser is located at a lower portion of the condenser.
Description
Technical Field
The present application relates to a purification apparatus for (meth) acrylonitrile.
Background
In a process for producing acrylonitrile by reacting propylene and/or propane, ammonia and molecular oxygen in the presence of a catalyst, after separating acetonitrile from produced acrylonitrile, acetonitrile, hydrocyanic acid and water are separated by a distillation operation to recover acrylonitrile. This distillation column is also referred to as a dehydrocyanation dehydration column. Since hydrocyanic acid is polymerized in the upper part (hydrocyanic acid portion) of the dehydrocyanation dehydration column or acrylonitrile is polymerized in the lower part (dehydration portion) of the dehydrocyanation dehydration column, the tray may be clogged, and it may be difficult to stably operate the distillation column for a long period of time.
In order to prevent the polymerization of acrylonitrile and hydrocyanic acid in the distillation column, for example, as described in patent document 1, it is conceivable to add hydroquinone and acetic acid to the column liquid of the distillation column in such a manner that the specific values are or more. Thereby inhibiting polymerization of acrylonitrile and hydrocyanic acid.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2007-39403 (Japanese patent No. 4959158)
SUMMERY OF THE UTILITY MODEL
Problem to be solved by utility model
In the above process, a gas generated by heating a solution containing (meth) acrylonitrile, hydrogen cyanide and water, which is supplied to a dehydrocyanation dehydration column, is supplied from the dehydrocyanation dehydration column to a condenser, and a condensate generated by condensing the gas in the condenser may be refluxed to the dehydrocyanation dehydration column. In the reflux step, it is generally considered to use a pump or the like to reflux the condensate to the dehydrocyanation dehydration column with high efficiency, but in this case, hydrogen cyanide may leak to the outside. In addition, when a pump or the like is used, although washing water for preventing clogging is required, the washing water promotes polymerization of hydrogen cyanide, and thus a tray in the dehydrocyanation dehydration column is clogged, and there is a possibility that the distillation column cannot be stably operated for a long period of time.
Accordingly, an object of the present invention is to provide a distillation apparatus used in a method for purifying (meth) acrylonitrile or hydrogen cyanide, which can efficiently reflux without using a pump or the like in a process for purifying (meth) acrylonitrile or hydrogen cyanide, and can stably operate for a long period of time by suppressing leakage of (meth) acrylonitrile or hydrogen cyanide and clogging of a tray of a dehydrocyanation dehydration column due to contamination.
Means for solving the problems
The present applicant has made extensive studies and, as a result, has found that the above-mentioned problems can be solved by designing a connection structure of a distillation column, a condenser and a reflux pipe to be a specific structure in a distillation apparatus including the distillation column, the condenser connected to the distillation column, and the reflux pipe to reflux condensate from an outlet of the condenser to the distillation column, and has completed the present application.
That is, the present application is as follows.
[1] A distillation apparatus for purifying (meth) acrylonitrile or hydrogen cyanide from a solution containing (meth) acrylonitrile, hydrogen cyanide and water, the distillation apparatus comprising a distillation column and a condenser connected to the distillation column,
the distillation column is provided with a reflux pipe for refluxing the condensate from an outlet of the condenser to the distillation column, wherein one end of the reflux pipe is connected to the outlet of the condenser, the other end of the reflux pipe is connected to an upper portion of the distillation column, and the outlet of the condenser is positioned at a lower portion of the condenser.
[2] The distillation apparatus according to [1], wherein the distillation apparatus is provided with a supply pipe for supplying a gas from the distillation column to the condenser, one end of the supply pipe is connected to a column top of the distillation column, and the other end of the supply pipe is connected to an upper portion of the condenser.
[3] The distillation apparatus according to [1], wherein the height position of the outlet of the condenser is formed higher than the height position of the uppermost end of the distillation column.
[4] The distillation apparatus according to [3], wherein a distance between a height position of an outlet of the condenser and a height position of an uppermost end of the distillation column is 10 to 1000 cm.
[5] The distillation apparatus according to [3], wherein a distance between a height position of an outlet of the condenser and a height position of an uppermost end of the distillation column is 10 to 500 cm.
[6] The distillation apparatus according to [3], wherein the distance between the height of the outlet of the condenser and the height of the uppermost end of the distillation column is 10 to 300 cm.
[7] The distillation apparatus according to [1], wherein the distillation apparatus is provided with a reflux pipe for refluxing the condensate from an outlet of the condenser to the distillation column, and a height position of a lowermost end of the reflux pipe is formed to be lower than a height position of a connection port of the reflux pipe of the distillation column.
[8] The distillation apparatus according to [7], wherein a height position of a lowermost end of the reflux pipe is lower by 10cm or more than a height position of a connection port of the reflux pipe of the distillation column.
[9] The distillation apparatus according to [7], wherein a height position of a lowermost end of the reflux pipe is lower by 100cm or more than a height position of a connection port of the reflux pipe of the distillation column.
[10] The distillation apparatus according to [1], wherein the condenser is provided outside the distillation column.
Effect of the utility model
According to the distillation apparatus and the purification method of the present application, in the purification step of (meth) acrylonitrile or hydrogen cyanide, reflux can be efficiently performed without using a pump or the like, leakage of hydrogen cyanide is suppressed, clogging of trays in a dehydrocyanation dehydration column due to contamination is suppressed, and stable operation can be achieved for a long period of time.
Drawings
Fig. 1 is a schematic diagram showing an example of a distillation apparatus according to the present embodiment.
Fig. 2 is a schematic diagram showing an example of the distillation apparatus of the present embodiment.
Detailed Description
Hereinafter, embodiments of the present application (hereinafter, referred to as "the present embodiment") will be described in detail with reference to the drawings. The present application is not limited to the following description, and various modifications can be made within the spirit of the present application. In the drawings, the same elements are denoted by the same reference numerals, and the description thereof will not be repeated. In addition, for positional relationships such as up, down, left, and right, positional relationships shown in the drawings shall be used unless otherwise specified. The dimensional scale of the drawings is not limited to the illustrated scale.
[ (meth) acrylonitrile or hydrogen cyanide purification method ]
The method for purifying (meth) acrylonitrile or hydrogen cyanide according to the present embodiment is a method for purifying (meth) acrylonitrile or hydrogen cyanide from a solution containing (meth) acrylonitrile, hydrogen cyanide, and water (hereinafter referred to as "a (meth) acrylonitrile-containing solution") using a distillation apparatus including a distillation column and a condenser connected to the distillation column, the method including: a supply step of supplying a gas (hereinafter, also referred to as "gas") generated by heating the solution supplied to the distillation column from the distillation column to the condenser; and a reflux step of refluxing a condensate generated by condensing the gas supplied in the supply step to the distillation column from an outlet of the condenser.
In the purification method, a reflux pipe for refluxing the condensate from an outlet of the condenser to the distillation column is provided, one end of the reflux pipe is connected to the outlet of the condenser, the other end of the reflux pipe is connected to an upper portion of the distillation column, an outlet of the condenser is located at a lower portion of the condenser, and in the reflux step, the condensate is supplied from the outlet of the condenser to the upper portion of the distillation column via the reflux pipe.
In general, in the reflux step, a pump (for example, a sealed pump) is required to efficiently reflux the condensate to the distillation column, but in this case, hydrogen cyanide may leak to the outside. In addition, it is also considered that hydrogen cyanide polymerizes and clogs in dead spaces in the pump, thus requiring flushing of the interior with water. However, in the case of flushing with water, ionization of hydrogen cyanide in the distillation column is promoted, and contamination in the column may result in failure to continue the operation. In contrast, in the purification method of the present embodiment, one end of the reflux pipe is connected so as to be positioned at the lower portion of the condenser, the other end of the reflux pipe is connected so as to be positioned at the upper portion of the distillation column, and the condensate is supplied from the outlet of the condenser to the upper portion of the distillation column via the reflux pipe.
Thus, the condensed liquid can be efficiently refluxed from the outlet of the condenser to the distillation column by utilizing the potential energy without using a pump or the like. Therefore, the leakage of hydrogen cyanide to the outside does not occur, and the tray in the distillation column is not clogged by the acceleration of the polymerization of hydrogen cyanide, and the distillation column can be stably operated for a long period of time.
[ distillation apparatus ]
The distillation apparatus used in the purification method of the present embodiment will be described below with reference to fig. 1. The distillation apparatus 10 shown in fig. 1 comprises: a distillation column 1; a condenser 2 connected to the distillation column 1; a supply pipe 3 for supplying gas from the distillation column 1 to the condenser 2; a reflux pipe 4 for refluxing the condensate from the outlet of the condenser 2 to the distillation column 1; and a discharge pipe 5 for discharging hydrogen cyanide gas that has not been condensed in the condenser 2 to the outside. The height of the outlet of the condenser 2 is higher than the height of the uppermost end of the distillation column 1. One end of the supply pipe 3 is connected to the top of the distillation column 1, and the other end of the supply pipe 3 is connected to the upper part of the condenser 2. One end of the reflux pipe 4 is connected to the outlet of the condenser 2, and the other end of the reflux pipe 4 is connected to the upper part of the distillation column 1. The height of the lowermost end of the reflux pipe 4 is set lower than the height of the connection port of the reflux pipe 4 of the distillation column 1. In the present specification, the term "upper portion" means a portion having a height in the range of 0 to 0.5 when the height from the uppermost end to the lowermost end of the distillation column is 1.
Hereinafter, a method for purifying (meth) acrylonitrile or hydrogen cyanide from a (meth) acrylonitrile-containing solution will be described with reference to the distillation apparatus 10 shown in fig. 1.
(supply step)
In the supply step, a gas generated by heating the (meth) acrylonitrile-containing solution supplied to the distillation column 1 is supplied from the distillation column 1 to the condenser 2. In this step, it is preferable to supply gas from the top of the distillation column 1 to the upper part of the condenser 2 through the supply pipe 3.
(refluxing procedure)
In the reflux step, a condensate produced by condensing the gas supplied in the supply step is refluxed to the distillation column 1 from the outlet of the condenser 2. In this step, the condensate is supplied from the outlet of the condenser 2 to the upper part of the distillation column 1 via the reflux pipe 4. Thus, the condensed liquid can be efficiently refluxed from the outlet of the condenser to the distillation column by utilizing the potential energy without using a pump or the like.
Here, the height position of the lowermost end of the reflux pipe 4 is formed to be lower than the height position of the connection port of the reflux pipe 4 of the distillation column 1. Thus, in the reflux step, the reflux pipe 4 is filled with the condensate, and the gas in the distillation column 1 tends to be prevented from flowing back.
The distance between the height position of the lowermost end and the height position of the connection port of the return pipe 4 is preferably 10cm or more lower, and more preferably 100cm or more lower. This tends to further prevent the condensate from flowing backward.
The difference (pressure difference) between the pressure in the distillation column 1 and the pressure in the condenser 2 is preferably 0.010 to 0.015kgf/cm2. This tends to further prevent the condensate from flowing backward.
The purification process may further comprise: and a step of discharging the hydrogen cyanide gas that has not been condensed in the condenser 2 to the outside through the discharge pipe 5.
In this process, the uncondensed hydrogen cyanide or a part of the condensed hydrogen cyanide can be discharged to the outside. In this step, the hydrogen cyanide to be discharged may be in the form of a liquid or a vapor (gas). The hydrogen cyanide discharged may be produced as a sodium salt or a calcium salt, or may be used as a raw material for another step. When the hydrogen cyanide is used as a raw material in another step, the hydrogen cyanide is reacted with acetone to be used as a raw material for methyl methacrylate, for example.
In order to prevent polymerization of acrylonitrile and hydrocyanic acid in the distillation column 1, the purification step may include a step of adding at least one of hydroquinone and acid (e.g., acetic acid, sulfuric acid, phosphoric acid, and glycolic acid) to the column liquid of the distillation column 1. In this step, for example, hydroquinone may be supplied as an aqueous solution from the top of the distillation column 1. The concentration of hydroquinone in the bottom liquid of the distillation column 1 may be, for example, about 100 to 600 mass ppm. In this step, for example, an acid may be supplied to the supply pipe 3. The concentration of the acid in the bottom liquid of the distillation column 1 is, for example, about 1000 to 3000 ppm by mass.
The distillation apparatus used in the purification method of the present embodiment is not necessarily limited to the distillation apparatus 10 shown in fig. 1, and may be any apparatus including a distillation column and a condenser connected to the distillation column, and including a reflux pipe for refluxing the condensate from an outlet of the condenser to the distillation column, wherein one end of the reflux pipe is connected to an outlet of the condenser, the other end of the reflux pipe is connected to an upper portion of the distillation column, and an outlet of the condenser is located at a lower portion of the condenser.
In the distillation apparatus, it is preferable that the height of the outlet of the condenser is higher than the height of the uppermost end of the distillation column.
Thus, the condensed liquid can be efficiently refluxed from the outlet of the condenser to the distillation column by utilizing the potential energy without using a pump or the like.
The distance between the height of the outlet of the condenser and the height of the uppermost end of the distillation column is preferably 10cm to 1000cm, more preferably 10cm to 500cm, and still more preferably 10cm to 300 cm.
This can suppress the accumulation of the condensate in the lower portion of the condenser, and can prevent a large amount of mist from flowing into the pipe for extracting the gas containing hydrogen cyanide.
The condenser attached to the distillation apparatus is preferably a vertical multitubular heat exchanger. Thus, the effect of adding the antifouling acid tends to be further improved.
In the distillation apparatus, the condenser is preferably provided outside the distillation column and has a heat exchanger. Thus, JET cleaning tends to be easier.
The distillation apparatus preferably does not comprise a flow meter. This makes it possible to further reduce the pressure loss in the return line and to further suppress the leakage of hydrogen cyanide.
[ (meth) acrylonitrile preparation method ]
The method for producing (meth) acrylonitrile according to the present embodiment is a method for producing (meth) acrylonitrile by subjecting a raw material gas, ammonia, and oxygen to an ammoxidation reaction in the presence of a catalyst, the method including: a purification step of purifying (meth) acrylonitrile or hydrogen cyanide from a solution containing (meth) acrylonitrile, hydrogen cyanide, and water, the purification step using the purification method of the present embodiment.
(raw gas)
The raw material gas is not particularly limited, but is preferably 1 or more selected from the group consisting of propane, propylene, isobutylene, and tert-butyl alcohol.
Examples
The present embodiment will be described in detail below with reference to examples, but the present embodiment is not limited to the following examples.
[ example 1]
The distillation apparatus shown in fig. 1 was used as the distillation apparatus. A liquid containing 89 mass% of acrylonitrile, 2 mass ppm of acetonitrile, 5 mass% of hydrogen cyanide and 4 mass% of water, which was obtained by separating acetonitrile from a reaction product obtained by reacting propylene, ammonia and air, was supplied to the 37 th layer in the upper part of a distillation column, which is a plate column having 55 layers, at a flow rate of 22T/hr. At the top of the condenser, 1200Mcal of heat was removed every 1 hour, the gas discharged from the distillation column to the top of the condenser through the supply pipe was condensed, and the condensate produced by condensing the gas was refluxed from the condenser to the distillation column through the reflux pipe by gravity. Further, the uncondensed gas containing 85 mass% or more of hydrogen cyanide was discharged to the outside through a gas pipe connected to a side surface of the condenser. In order to prevent contamination of the interior of the supply pipe, acetic acid was sprayed and supplied into the supply pipe by spraying and dispersed throughout the condenser, so that the concentration of acetic acid in the condensate of the condenser was 2000 mass ppm. After 1 year of operation under these operating conditions, the heat transfer efficiency of the condenser was not reduced, and the reflux piping and the column were not clogged, and stable operation was possible.
Since the reflux piping is filled with a liquid, the reflux of the overhead vapor of the dehydrocyanation dehydration column in the reflux piping is suppressed, and the purity of hydrogen cyanide in the uncondensed hydrogen cyanide-containing gas is stabilized.
Further, there was no accumulation of condensate in the lower portion of the condenser, and a large amount of mist flowed into the piping for extracting the hydrogen cyanide-containing gas could be suppressed, and no contamination of the piping was observed.
[ example 2]
Acrylonitrile was produced under the same conditions as in example 1 for 1 year except that a reflux pipe for refluxing the condensate from the condenser to the dehydrocyanation dehydration column was branched and the purified hydrogen cyanide liquid was sent to another step, and as a result, the heat transfer efficiency of the condenser was not lowered, the reflux pipe and the column were not clogged, and stable operation was possible, as in example 1.
[ example 3]
Acrylonitrile was produced under the same conditions as in example 1 for 1 year except that the height of the lowermost end of the reflux pipe for refluxing the condensate from the condenser to the dehydrocyanic acid dehydration column was the same as the height of the connection port between the dehydrocyanic acid dehydration column and the reflux pipe, and as a result, the operation was carried out in a state where the heat transfer efficiency of the condenser was not lowered and the reflux pipe and the column were not clogged, as in example 1.
[ example 4]
Acrylonitrile was produced under the same conditions as in example 1 for 1 year, except that the height of the lowermost end of the reflux pipe for refluxing the condensate from the condenser to the dehydrocyanic acid dehydration column was the same as the height of the connection port between the dehydrocyanic acid dehydration column and the reflux pipe, and the height of the outlet of the condenser was lower than the height of the top of the dehydrocyanic acid dehydration column, and as a result, the operation was carried out in a state where the heat transfer efficiency of the condenser was not lowered and the reflux pipe and the column were not clogged, as in example 1.
Comparative example 1
The operation was carried out under the same conditions as in example 1 except that a distillation apparatus shown in fig. 1 was not used, but a generally used distillation apparatus was used, a condensate produced by condensing a gas in a condenser was refluxed from the condenser to a distillation column by a pump, a reflux flow rate was measured by a differential pressure type flow meter, and the insides of pressure guide pipes of the pump and the flow meter were flushed with water. The polymer of hydrogen cyanide was produced in the distillation column, and the trays were clogged, and the operation could not be continued for 6 months.
Claims (10)
1. A distillation apparatus for purifying (meth) acrylonitrile or hydrogen cyanide from a solution containing (meth) acrylonitrile, hydrogen cyanide and water, the distillation apparatus comprising a distillation column and a condenser connected to the distillation column,
the distillation column is provided with a reflux pipe for refluxing the condensate from an outlet of the condenser to the distillation column, wherein one end of the reflux pipe is connected to the outlet of the condenser, the other end of the reflux pipe is connected to an upper portion of the distillation column, and the outlet of the condenser is positioned at a lower portion of the condenser.
2. The distillation apparatus according to claim 1, wherein the distillation apparatus comprises a supply pipe for supplying the gas from the distillation column to the condenser, one end of the supply pipe is connected to a column top of the distillation column, and the other end of the supply pipe is connected to an upper portion of the condenser.
3. The distillation apparatus according to claim 1, wherein a height position of an outlet of the condenser is formed higher than a height position of an uppermost end of the distillation column.
4. The distillation apparatus according to claim 3, wherein a distance between a height position of the outlet of the condenser and a height position of the uppermost end of the distillation column is 10 to 1000 cm.
5. The distillation apparatus according to claim 3, wherein a distance between a height position of the outlet of the condenser and a height position of the uppermost end of the distillation column is 10 to 500 cm.
6. The distillation apparatus according to claim 3, wherein a distance between a height position of the outlet of the condenser and a height position of the uppermost end of the distillation column is 10 to 300 cm.
7. The distillation apparatus according to claim 1, wherein the distillation apparatus is provided with a reflux pipe for refluxing the condensate from an outlet of the condenser to the distillation column, and a height position of a lowermost end of the reflux pipe is formed to be lower than a height position of a connection port of the reflux pipe of the distillation column.
8. The distillation apparatus according to claim 7, wherein a height position of a lowermost end of the reflux pipe is lower by 10cm or more than a height position of a connection port of the reflux pipe of the distillation column.
9. The distillation apparatus according to claim 7, wherein a height position of a lowermost end of the reflux pipe is lower by 100cm or more than a height position of a connection port of the reflux pipe of the distillation column.
10. The distillation apparatus of claim 1, wherein the condenser is disposed outside the distillation column.
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| CN202020105180.0U Active CN212335081U (en) | 2019-01-29 | 2020-01-17 | Distillation apparatus for purifying (meth) acrylonitrile or hydrogen cyanide |
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| JP3907749B2 (en) * | 1996-07-09 | 2007-04-18 | 旭化成ケミカルズ株式会社 | Purification method of acetonitrile |
| US5840955A (en) * | 1997-11-25 | 1998-11-24 | Sockell; Edward J. | Waste minimization and product recovery process |
| CN1195757A (en) * | 1998-02-26 | 1998-10-14 | 李世维 | Back-flow device and water heater |
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| JP5605921B2 (en) * | 2010-12-27 | 2014-10-15 | 旭化成ケミカルズ株式会社 | Purification method of acrylonitrile |
| CN103261151B (en) * | 2010-12-27 | 2015-04-22 | 旭化成化学株式会社 | Method for purifying acrylonitrile |
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| CN103508847B (en) * | 2013-09-30 | 2016-06-08 | 天津大学 | A kind of method of high-purity butanols of butanols dewatering and recovery and device |
| CN103804230A (en) * | 2014-01-29 | 2014-05-21 | 中国石油集团东北炼化工程有限公司吉林设计院 | Method for reducing content of methacrylonitrile in acrylonitrile and acrylonitrile production system |
| EP3530647A4 (en) * | 2016-10-21 | 2019-10-16 | Asahi Kasei Kabushiki Kaisha | Purification method, production process, and distillation device for acrylonitrile |
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