CN117101550A - Production device and production method for synthesizing acetic acid by low-pressure carbonylation of methanol - Google Patents

Abstract

The application discloses a production device and a production method for synthesizing acetic acid by methanol low-pressure carbonylation, wherein the production device comprises the following components: a reaction kettle, a flash evaporation tower, a dehydration tower and a finished product tower; the reaction kettle is used for feeding CO and methanol into the reaction kettle, and a material flow containing acetic acid and a catalyst is extracted from the reaction kettle; the pipeline of the material flow containing the acetic acid and the catalyst is connected with a flash tower so that the material flow containing the acetic acid and the catalyst is separated in the flash tower, and a material flow containing the crude acetic acid is extracted from the flash tower; a pipeline of the material flow containing the crude acetic acid is connected with a dehydration tower for further separating the material flow containing the crude acetic acid, and the material flow containing the acetic acid and the propionic acid is extracted from the tower bottom of the dehydration tower; the pipeline of the material flow containing acetic acid and propionic acid is connected with the finished product tower to further separate the material flow containing acetic acid and propionic acid in the finished product tower, and acetic acid product is obtained from the middle part of the finished product tower, and the product obtained by the production device has high purity and reduces energy consumption.

Description

Production device and production method for synthesizing acetic acid by low-pressure carbonylation of methanol

Technical Field

The application relates to the technical field of production of acetic acid by low-pressure carbonylation of methanol, in particular to a production device and a production method of acetic acid by low-pressure carbonylation of methanol.

Background

In the prior art, acetic acid steam at the top of a finished product tower is utilized to heat a dehydration tower in the acetic acid synthesis process of methanol low-pressure carbonyl, the prior art has the problems that the material of the dehydration tower is high, the investment of low-pressure operation equipment is large, in addition, light component impurities exist in the feeding of the dehydration tower, the temperature of a low-pressure operation condenser is too low, even methyl iodide cannot be condensed, the light components such as methyl iodide cannot return to a reaction kettle, the balance of a system is lost, the material loss is large, in addition, the finished product tower in the prior art adopts pressurization operation, the operation temperature can be increased after pressurization, and the corrosion of equipment can be aggravated.

Disclosure of Invention

Aiming at the technical problems, the application provides a production device and a production method for synthesizing acetic acid by methanol low-pressure carbonylation, wherein the production device comprises a reaction kettle, a flash evaporation tower, a dehydration tower and a finished product tower, the dehydration tower adopts positive pressure operation, the higher the pressure under the same treatment capacity is, the smaller the tower diameter is, and the investment cost of zirconium equipment is not increased; meanwhile, the finished product tower is adjusted to be in vacuum operation, the diameter of the tower is increased after being adjusted to be in vacuum, however, because the material of the finished product tower is 316L, the investment increase of equipment is little because of the diameter increase, in addition, after the finished product tower is operated by adopting negative pressure, the operating temperature is greatly reduced, the corrosion rate of the equipment is reduced after the temperature is reduced, the service period of the tower adopting 316L material is longer, the overhaul and maintenance period is reduced, the separation efficiency of acetic acid and heavy component impurities (mainly propionic acid) is improved after the negative pressure operation is adopted, and the product quality is improved. In addition, the finished product tower can adopt a partition rectifying tower, and the purity of the acetic acid product can be further improved.

The specific technical scheme of the application is as follows:

1. a production apparatus for synthesizing acetic acid by methanol low-pressure carbonylation, comprising:

a reaction kettle, a flash evaporation tower, a dehydration tower and a finished product tower;

the reactor is connected to a line for the CO stream and a line for the methanol stream for feeding CO and methanol to the reactor,

the reaction kettle is used for carrying out a reaction between CO and methanol to obtain a material flow containing acetic acid and a catalyst;

the reaction kettle is connected with a pipeline of a material flow containing acetic acid and catalyst so as to extract the material flow containing acetic acid and catalyst from the reaction kettle;

the pipeline of the material flow containing the acetic acid and the catalyst is connected with a flash tower so that the material flow containing the acetic acid and the catalyst is separated in the flash tower, and a material flow containing the crude acetic acid is extracted from the flash tower;

a pipeline of the material flow containing the crude acetic acid is connected with a dehydration tower for further separating the material flow containing the crude acetic acid, the material flow containing the acetic acid and the propionic acid is extracted from the tower bottom of the dehydration tower, and the material flow containing water, methyl iodide, methanol and methyl acetate is extracted from the tower top of the dehydration tower;

connecting a pipeline of a material flow containing acetic acid and propionic acid with the finished product tower to further separate the material flow containing acetic acid and propionic acid in the finished product tower, separating an acetic acid product from the middle part of the finished product tower, extracting the material flow containing water and acetic acid from the top of the finished product tower, and extracting the material flow containing propionic acid from the tower bottom of the finished product tower.

2. The production apparatus according to item 1, wherein the finishing column is provided with a heat exchanger, and the top of the dehydrating column and the bottom of the finishing column are connected to the heat exchanger through a pipeline so as to use the vapor at the top of the dehydrating column as a heat source of the bottom of the finishing column.

3. The production apparatus according to item 1 or 2, wherein the final product column is a divided wall rectifying column.

4. The production apparatus according to any one of claims 1 to 3, wherein the dehydration column is provided with a reboiler, and a column bottom of the dehydration column and a middle portion of the reaction vessel are connected to the reboiler through a pipeline to supply reaction heat or steam in the column bottom of the dehydration column and the middle portion of the reaction vessel to the dehydration column.

5. The production apparatus according to any one of claims 1 to 4, wherein the top of the reaction vessel is connected to a line for a stream containing methyl iodide and CO.

6. The production apparatus according to item 5, wherein the production apparatus comprises a separator, and the top of the flash column is connected to a line of a stream containing methyl iodide and CO extracted from the top of the reaction vessel via a line, and is connected to the separator, and a stream containing the catalyst is extracted from the bottom of the flash column and returned to the reaction vessel.

7. The production apparatus according to item 6, wherein the stream containing water, methyl acetate and acetic acid separated from the separator is connected to the upper part of the flash column and the reaction vessel, respectively, through a line, and the stream containing methyl iodide and methyl acetate is connected to the reaction vessel through a line.

8. The production apparatus according to any one of claims 5 to 7, wherein the production apparatus comprises a separation tank to which a line for a stream containing methyl iodide and CO is connected for separating the stream containing methyl iodide and CO, a stream containing CO is withdrawn from the top of the separation tank, and a stream containing methyl iodide withdrawn from the bottom of the separation tank is returned to the reaction vessel with a material withdrawn from the top of the flash column being connected to a separator through a line.

9. A method for producing methanol low pressure carbonylation synthesis acetic acid using the production apparatus of any one of claims 1-8, comprising:

feeding the CO stream and the methanol stream into a reaction kettle for reaction to obtain a stream containing acetic acid and a catalyst, and extracting the stream containing the acetic acid and the catalyst from the reaction kettle;

the material flow containing acetic acid and catalyst enters a flash tower for separation, and a material flow containing crude acetic acid is extracted from the flash tower;

Feeding the material flow containing the crude acetic acid into a dehydration tower to separate the material flow containing the crude acetic acid, extracting the material flow containing acetic acid and propionic acid from the tower bottom of the dehydration tower, and extracting the material flow containing water, methyl iodide and methyl acetate from the tower top of the dehydration tower;

the material flow containing acetic acid and propionic acid enters into the finished product tower to separate the material flow containing acetic acid and propionic acid, acetic acid products are extracted from the middle part of the finished product tower, the material flow containing water and acetic acid is extracted from the top of the finished product tower, and the material flow containing propionic acid is extracted from the tower bottom of the finished product tower.

10. The process of claim 9, wherein a stream comprising methyl iodide and CO is withdrawn from the top of the reaction vessel.

11. The process according to claim 9 or 10, wherein the stream comprising methyl iodide and CO and the stream withdrawn from the top of the flash column are fed to a separator for separation, and the stream comprising the catalyst is withdrawn from the bottom of the flash column and returned to the reaction vessel.

12. The process according to item 11, wherein the stream containing water, methyl acetate and acetic acid separated from the separator is fed to the upper part of the flash column and the reaction vessel, respectively, and the stream containing methyl iodide and methyl acetate is fed back to the reaction vessel.

13. The process of any one of claims 10-12, wherein the stream comprising methyl iodide and CO is fed to a separation tank for separation, the stream comprising CO is withdrawn from the top of the separation tank and fed to a separator from the material withdrawn from the top of the flash column, and the stream comprising methyl iodide withdrawn from the bottom of the separation tank is returned to the reaction vessel.

14. The process according to any one of claims 9 to 13, wherein the pressure of the dehydration column is 120 to 500kpa g, preferably 160 to 250kpa g; and/or

The temperature of the tower bottom of the dehydration tower is 140-200 ℃; and/or

The temperature of the top of the dehydration tower is 100-160 ℃; and/or

The number of the tower trays of the dehydration tower is 45-120; and/or

The pressure of the flash tower is 80-250KpaG, preferably 100-180KpaG; and/or

The temperature of the top of the flash tower is 80-150 ℃; and/or

The temperature of the tower bottom of the flash tower is 110-150 ℃.

15. The process of any one of claims 9-14, wherein the pressure of the finishing column is from-99 to 70kpa g; and/or

The temperature of the tower bottom of the finished product tower is 80-140 ℃; and/or

The temperature of the top of the finished product tower is 50-130 ℃; and/or

The number of tower tray layers of the finished product tower is 50-150.

16. The process of any one of claims 9-15, wherein the acetic acid product has a purity of 99.8-99.99%.

ADVANTAGEOUS EFFECTS OF INVENTION

The production device provided by the application has the advantages that the flow is more reasonable, the investment of zirconium equipment is reduced, the product quality is higher, the operating temperature of a finished product tower is reduced, the corrosion rate of internal parts of the finished product tower is reduced, and the equipment operation period is prolonged.

The production device disclosed by the application uses the steam at the top of the dehydration tower to exchange heat for the finished product tower kettle, so that double-effect rectification is realized, steam consumption is reduced, meanwhile, circulating water cooling is not used at the top of the dehydration tower, and the consumption of circulating water is saved.

The finished product tower of the device can adopt a partition rectifying tower, so that the purity of the product can be further improved, and the total equipment quantity is small, thereby greatly reducing the total equipment investment.

The method is simple to operate, the purity of the obtained acetic acid product is high, and the dehydration tower and the finished product tower are adopted for double-effect rectification and the reaction heat is utilized for heating the dehydration tower, so that the consumption of steam and circulating water is reduced, and the whole production device can save energy by more than 40 percent.

Drawings

FIG. 1 is a schematic diagram of an embodiment of the present application.

Fig. 2 is a schematic diagram of a finishing column as a divided wall rectifying column.

Fig. 3 is a schematic diagram of an embodiment of the present application.

Fig. 4 is a schematic diagram of an embodiment of the present application.

Fig. 5 is a schematic diagram of an embodiment of the present application.

The device comprises a 1-reaction kettle, a 2-flash tower, a 3-dehydration tower, a 4-finished product tower, a 5-layering device, a 6-high pressure separator, a 7-reaction tail gas cooler, an 8-mother liquid pump, a 10-external circulation pump, an 11-primary cooler, a 12-flash tower reflux pump, a 13-heavy phase pump, a 14-flash tower reboiler, a 15-dehydration tower feed pump, a 16-dehydration tower reboiler A, a 17-dehydration tower reboiler B, a 18-finished product tower feed pump, a 19-dehydration tower reflux pump, a 20-dehydration tower reflux tank, a 21-dehydration tower condenser/finished product tower reboiler, a 22-finished product tower condenser, a 23-finished product tower reflux tank, a 24-finished product tower reflux pump, a 25-acetic acid product cooler and a 26-stripping tower feed pump; 27-final cooler, 28-light ends column, 29-pre-wash column, 30-flash vessel, 31-light ends column reflux pump, 32-light ends column reboiler, 101-CO stream, 102-methanol stream, 103-stream containing water, methyl acetate and acetic acid, 104-stream containing water, methyl iodide, methanol and methyl acetate, 105-stream containing methyl iodide and methyl acetate, 108-stream containing acetic acid and catalyst, 109-stream containing methyl iodide and CO, 110-stream containing CO, 111-stream containing methyl iodide, 112-stream containing catalyst, 115-stream containing CO, methyl acetate, methyl iodide and water, 116-stream containing CO, acetic acid, methyl acetate, methyl iodide, catalyst and water, 117-stream containing crude acetic acid, 121-stream containing acetic acid and propionic acid, 122-stream containing water and acetic acid, 124-acetic acid product, 125-stream containing propionic acid, 129/130-stream containing acetic acid and catalyst, 131-stream containing CO, acetic acid, methyl iodide, methyl acetate and water.

Detailed Description

The application is described in detail below in connection with the embodiments described. While specific embodiments of the application are shown, it should be understood that the application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

It should be noted that certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will understand that a person may refer to the same component by different names. The specification and claims do not identify differences in terms of components, but rather differences in terms of the functionality of the components. As referred to throughout the specification and claims, the terms "include" or "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description hereinafter sets forth a preferred embodiment for practicing the application, but is not intended to limit the scope of the application, as the description proceeds with reference to the general principles of the description. The scope of the application is defined by the appended claims.

The application provides a production device for synthesizing acetic acid by methanol low-pressure carbonylation, which comprises:

a reaction kettle, a flash evaporation tower, a dehydration tower and a finished product tower;

the reactor is connected to a line for the CO stream and a line for the methanol stream for feeding CO and methanol to the reactor,

the reaction kettle is used for carrying out the reaction of CO and methanol to obtain a material flow containing acetic acid and a catalyst,

the reaction kettle is connected with a pipeline of a material flow containing acetic acid and catalyst so as to extract the material flow containing acetic acid and catalyst from the reaction kettle;

the pipeline of the material flow containing the acetic acid and the catalyst is connected with a flash tower so that the material flow containing the acetic acid and the catalyst is separated in the flash tower, and a material flow containing the crude acetic acid is extracted from the flash tower;

a pipeline of the material flow containing the crude acetic acid is connected with a dehydration tower for further separating the material flow containing the crude acetic acid, the material flow containing the acetic acid and the propionic acid is extracted from the tower bottom of the dehydration tower, and the material flow containing water, methyl iodide, methanol and methyl acetate is extracted from the tower top of the dehydration tower;

connecting a pipeline of a material flow containing acetic acid and propionic acid with the finished product tower to further separate the material flow containing acetic acid and propionic acid in the finished product tower, separating an acetic acid product from the middle part of the finished product tower, extracting the material flow containing water and acetic acid from the top of the finished product tower, and extracting the material flow containing propionic acid from the tower bottom of the finished product tower. In some embodiments, the catalyst system is a rhodium lithium iodide or iridium ruthenium catalyst.

In the application, the flash tower can be one device or a combination of a plurality of devices, for example, the flash tower can be a combination of a flash evaporator, a pre-washing tower for capturing catalyst and a light component removing tower, the flow operation is that a material flow containing acetic acid and catalyst extracted from a reaction kettle is connected with the flash evaporator for flash evaporation, the flash evaporation gas phase enters the pre-washing tower, the flash evaporation gas phase is washed by dilute acid in the pre-washing tower, the catalyst-containing acetic acid solution recovered by washing returns to the flash evaporator, the gas phase of the pre-washing tower enters the light component removing tower, and the material flow containing the crude acetic acid is extracted from the tower or the tower kettle; the process operation is that a material flow containing acetic acid and catalyst extracted from a reaction kettle is connected with the flash evaporator for flash evaporation, the flash evaporation gas phase enters the light component removing tower, the flash evaporation gas phase is washed by acetic acid at the lower part of the light component removing tower, the washed and recovered acetic acid solution containing the catalyst returns to the flash evaporator, the gas phase of the light component removing tower enters a condenser and a layering device, and the material flow containing the crude acetic acid is extracted from the tower of the light component removing tower. In some embodiments, the product tower is provided with a heat exchanger, and the top of the dehydration tower and the tower bottom of the product tower are connected with the heat exchanger through pipelines, so that steam at the top of the dehydration tower is used as a heat source of the tower bottom of the product tower.

The heat exchanger is arranged on the finished product tower, so that steam consumption can be greatly reduced.

For example, taking a 30 ten thousand ton acetic acid device as an example, a double-effect thermal coupling technology is not adopted, the heat value of steam required by two rectifying towers is about 20M Kcal, the heat removal of circulating water is 20M Kcal, the heat value of steam required by two towers after adopting the double-effect thermal coupling technology is 10M Kcal, the heat removal of circulating water is 10M Kcal, the heat value of steam required by two towers after adopting the double-effect thermal coupling technology for heating reaction and heat utilization is 9M Kcal, and the heat removal of circulating water is 10M Kcal, which indicates that the consumption of steam can be greatly reduced.

In some embodiments, the finished product tower is a partition rectifying tower, preferably, the partition plate can divide the finished product tower into four areas, namely a 1 st area serving as a feed inlet, a 2 nd area located at the top of the tower, a 4 th area located at the bottom of the tower and a 3 rd area located in the middle of the tower, a pipeline of a material flow containing acetic acid and propionic acid is connected with the 1 st area of the finished product tower, an acetic acid product is extracted from the 3 rd area of the finished product tower, a material flow containing water and acetic acid is extracted from the 2 nd area, and a material flow containing propionic acid is extracted from the 4 th area.

In some embodiments, the dehydration tower is provided with a reboiler, and the bottoms of the dehydration tower and the middle part of the reaction kettle are connected with the reboiler through pipelines so as to supply the reaction heat or steam in the bottoms of the dehydration tower and the middle part of the reaction kettle to the dehydration tower.

The application uses the reaction heat to heat the dehydration tower, which fully utilizes the waste heat of the device and further reduces the consumption of steam.

In some embodiments, the top of the reaction vessel is connected to a line containing a stream of methyl iodide and CO. In some embodiments, the production apparatus comprises a laminator, a stream comprising CO, methyl acetate, methyl iodide and water is withdrawn from the top of a flash column connected by a line comprising the stream comprising CO, methyl acetate, methyl iodide and water to a line comprising the stream comprising methyl iodide and CO withdrawn from the top of the reaction vessel and to the laminator, and a stream comprising catalyst is withdrawn from the bottom of the flash column and returned to the reaction vessel. In some embodiments, the stream comprising water, methyl acetate and acetic acid separated from the separator is connected to the upper portion of the flash column and the reaction vessel, respectively, by a line, and the stream comprising methyl iodide and methyl acetate is connected to the reaction vessel by a line.

The application adds a layering device, and can further layer the material flow to obtain the desired material flow.

In some embodiments, the production apparatus comprises a separation tank to which a line for a stream containing methyl iodide and CO is connected for separating the stream containing methyl iodide and CO, the stream containing CO is withdrawn from the top of the separation tank and connected to a separator by a line with the material withdrawn from the top of the flash column, and the stream containing methyl iodide withdrawn from the bottom of the separation tank is returned to the reaction vessel.

In some embodiments, the flash column comprises a flash vessel and a light ends column, the line containing the acetic acid and catalyst stream is connected to the flash vessel to flash the stream containing the acetic acid and catalyst, the stream containing CO, acetic acid, methyl acetate, methyl iodide, catalyst and water is withdrawn from the top of the flash vessel, the line containing the stream containing CO, acetic acid, methyl acetate, methyl iodide, catalyst and water is connected to the light ends column to further light the stream containing CO, acetic acid, methyl acetate, methyl iodide, catalyst and water, the stream containing CO, methyl acetate, methyl iodide and water is withdrawn from the top of the light ends column, the stream containing acetic acid and catalyst is withdrawn from the bottom of the light ends column, the stream containing crude acetic acid is withdrawn from the middle of the light ends column, and the line containing the stream containing CO, methyl acetate, methyl iodide and water is connected to the separator for further separation of the stream containing CO, methyl acetate, methyl iodide and water.

In some embodiments, the flash column comprises a flash vessel, a pre-wash column, and a light ends column, the lines containing the acetic acid and catalyst stream being connected to the flash vessel to flash the stream containing the acetic acid and catalyst, the lines containing the stream of CO, acetic acid, methyl acetate, methyl iodide, catalyst, and water being used from the top of the flash vessel, the lines containing the stream of CO, acetic acid, methyl acetate, methyl iodide, catalyst, and water being connected to the pre-wash column to further wash the stream containing CO, acetic acid, methyl acetate, methyl iodide, catalyst, and water, the stream containing CO, acetic acid, methyl acetate, methyl iodide, and water being withdrawn from the top of the pre-wash column, the stream containing acetic acid and catalyst being withdrawn from the bottom of the pre-wash column, the line containing the stream of CO, acetic acid, methyl acetate, methyl iodide, and water being connected to the light ends column to further light ends, the stream containing CO, acetic acid, methyl acetate, methyl iodide, and water being withdrawn from the top of the light ends column, and the stream containing the catalyst being withdrawn from the bottom of the light ends column.

FIG. 1 is a schematic diagram of an embodiment of the present application, as shown in FIG. 1, the production apparatus comprises a reaction kettle 1, a flash column 2, a dehydration column 3 and a finished product column 4, wherein the reaction kettle 1 is connected with a pipeline of a CO stream 101 and a pipeline of a methanol stream 102 for feeding CO and methanol to the reaction kettle, the reaction kettle 1 is connected with a pipeline of a stream 108 containing acetic acid and a catalyst for extracting the stream 108 containing acetic acid and the catalyst from the reaction kettle 1, and the catalyst is a rhodium lithium iodide catalyst or an iridium ruthenium catalyst; the top of the reactor 1 is connected to a line of a stream 109 containing methyl iodide and CO to withdraw a stream 109 containing methyl iodide and CO from the top;

the line of the acetic acid and catalyst containing stream 108 is connected to flash column 2 to separate the acetic acid and catalyst containing stream 108 in flash column 2 and a crude acetic acid containing stream 117 is withdrawn from flash column 2;

the production device comprises a delaminator 5, the top of the flash column 2 is connected with a pipeline of a stream 109 containing methyl iodide and CO, which is extracted from the top of the reaction kettle 1, and is connected with the delaminator 5, preferably connected with the delaminator 5 through a primary cooler 11, a stream 103 containing water, methyl acetate and acetic acid, which is separated from the delaminator 5, is respectively connected with the upper part of the flash column 2 and the reaction kettle 1 through a pipeline, preferably connected with the upper part of the flash column 2 and the reaction kettle 1 through a flash column reflux pump 12, and a separated stream 105 containing methyl iodide and methyl acetate is connected with the reaction kettle 1 through a pipeline, preferably connected with the reaction kettle 1 through a heavy phase pump 13; the catalyst-containing stream 112 withdrawn from the bottom of the flash column 2 is returned to the reaction vessel 1, preferably via the mother liquor pump 8, to the reaction vessel 1.

The line of stream 117 containing crude acetic acid is connected to dehydration column 3 for further separation of stream 117 containing crude acetic acid, preferably by connection to dehydration column 3 via dehydration column feed pump 15, stream 121 containing acetic acid and propionic acid is withdrawn from the bottom of dehydration column 3, stream 104 containing water, methyl iodide, methanol and methyl acetate is withdrawn from the top of dehydration column 3, preferably stream 104 is connected to dehydration column condenser/finishing column reboiler 21 and dehydration column reflux drum 20, and returned to dehydration column 3 via dehydration column reflux pump 19, with the additional withdrawn portion of stream 104 being returned to reaction vessel 1;

connecting a pipeline of a stream 121 containing acetic acid and propionic acid with the finishing column 4 to further separate the stream 121 containing acetic acid and propionic acid in the finishing column 4, separating an acetic acid product 124 from the middle part of the finishing column 4, introducing a stream 122 containing water and acetic acid extracted from the top of the finishing column 4 into a finishing column condenser 22 to be condensed, and returning the stream to the top of the finishing column 4 through a reflux drum 23, preferably through a finishing column reflux pump 24, and returning part of the stream 122 containing water and acetic acid to the dehydrating column 3, extracting a stream 125 containing propionic acid from the bottom of the finishing column 4;

the heat exchanger 21 is arranged on the finished product tower 4, and the tower top of the dehydrating tower 3 and the tower bottom of the finished product tower 4 are connected with the heat exchanger 21 through pipelines so as to take the steam at the tower top of the dehydrating tower 3 as a heat source of the tower bottom of the finished product tower 4.

The dehydration tower 3 is provided with a reboiler 16, and the bottoms of the dehydration tower 3 and the middle part of the reaction kettle 1 are connected with the reboiler 16 through pipelines so as to supply the reaction heat or steam in the bottoms of the dehydration tower 3 and the middle part of the reaction kettle 1 to the dehydration tower 3.

Fig. 2 is a schematic diagram of a finishing column 4 as a dividing wall rectifying column, the dividing wall dividing the finishing column 4 into four zones, namely zone 1, zone 2, zone 3 and zone 4, wherein a stream 121 containing acetic acid and propionic acid extracted from the dehydration column tank enters zone 1 of the finishing column, a stream containing water and acetic acid is extracted from zone 2, an acetic acid product 124 is extracted from zone 3, and a stream 125 containing propionic acid is extracted from zone 4.

FIG. 3 is a schematic diagram of an embodiment of the present application, as shown in FIG. 3, the production apparatus comprises a reaction vessel 1, a flash column 2, a dehydration column 3 and a finishing column 4, the reaction vessel 1 is connected with a pipeline of a CO stream 101 and a pipeline of a methanol stream 102 for feeding CO and methanol to the reaction vessel, the reaction vessel 1 is connected with a pipeline of a stream 108 containing acetic acid and a catalyst, the catalyst is a rhodium lithium iodide catalyst or an iridium ruthenium catalyst, and the stream 108 containing acetic acid and a catalyst is extracted from the reaction vessel 1; the top of the reactor 1 is connected to a line of a stream 109 containing methyl iodide and CO to withdraw a stream 109 containing methyl iodide and CO from the top;

The line of the acetic acid and catalyst containing stream 108 is connected to flash column 2 to separate the acetic acid and catalyst containing stream 108 in flash column 2 and a crude acetic acid containing stream 117 is withdrawn from flash column 2;

the production plant further comprises a separation tank 6, a line for a stream 109 comprising methyl iodide and CO being connected to the separation tank 6 for separating the stream 109 comprising methyl iodide and CO, a stream 110 comprising CO being withdrawn from the top of the separation tank 6, a stream 111 comprising methyl iodide being withdrawn from the bottom of the separation tank, which is returned to the reaction vessel 1.

The production device comprises a delaminator 5, the top of the flash tower 2 is connected with a pipeline containing a CO stream 110 from the top of a separation tank 6 through a pipeline, preferably condensed by a primary cooler 11 and connected with the delaminator 5, a stream 103 containing water, methyl acetate and acetic acid separated from the delaminator 5 is respectively connected with the upper part of the flash tower 2 and the reaction kettle 1 through a pipeline, preferably connected with the upper part of the flash tower 2 and the reaction kettle 1 through a flash tower reflux pump 12 respectively, and a separated stream 105 containing methyl iodide and methyl acetate is connected with the reaction kettle 1 through a pipeline, preferably connected with the reaction kettle 1 through a heavy phase pump 13; a catalyst-containing stream 112 is withdrawn from the bottom of flash column 2 and returned to reactor 1, preferably via mother liquor pump 8 to reactor 1.

The line of stream 117 containing crude acetic acid is connected to dehydration column 3 for further separation of stream 117 containing crude acetic acid, preferably by connection to dehydration column 3 via dehydration column feed pump 15, stream 121 containing acetic acid and propionic acid is withdrawn from the bottom of dehydration column 3, stream 104 containing water, methyl iodide, methanol and methyl acetate is withdrawn from the top of dehydration column 3, preferably stream 104 is connected to dehydration column condenser/finishing column reboiler 21 and dehydration column reflux drum 20, and returned to dehydration column 3 via dehydration column reflux pump 19, with the additional withdrawn portion of stream 104 being returned to reaction vessel 1.

Connecting a pipeline of a stream 121 containing acetic acid and propionic acid with the finishing column 4 to further separate the stream 121 containing acetic acid and propionic acid in the finishing column 4, separating an acetic acid product 124 from the middle part of the finishing column 4, introducing a stream 122 containing water and acetic acid extracted from the top of the finishing column 4 into a finishing column condenser 22 to be condensed, and returning the stream to the top of the finishing column 4 through a reflux drum 23, preferably through a finishing column reflux pump 24, and returning part of the stream 122 containing water and acetic acid to the dehydrating column 3, extracting a stream 125 containing propionic acid from the bottom of the finishing column 4;

the heat exchanger 21 is arranged on the finished product tower 4, and the tower top of the dehydrating tower 3 and the tower bottom of the finished product tower 4 are connected with the heat exchanger 21 through pipelines so as to take the steam at the tower top of the dehydrating tower 3 as a heat source of the tower bottom of the finished product tower 4.

The dehydration tower 3 is provided with a reboiler 16, and the bottoms of the dehydration tower 3 and the middle part of the reaction kettle 1 are connected with the reboiler 16 through pipelines so as to supply the reaction heat or steam in the bottoms of the dehydration tower 3 and the middle part of the reaction kettle 1 to the dehydration tower 3.

FIG. 4 is a schematic illustration of an embodiment of the application, as shown in FIG. 4, the production plant comprising a reaction vessel 1, a flash column (not shown), a dehydration column 3 and a finishing column 4, the flash column comprising a flash vessel 30 and a light ends column 28, the reaction vessel 1 being connected to a line for CO stream 101 and a line for methanol stream 102 for feeding CO and methanol to the reaction vessel, the reaction vessel 1 being connected to a line for acetic acid and catalyst containing stream 108 to withdraw from the reaction vessel acetic acid and catalyst containing stream 108, the catalyst being a rhodium lithium iodide catalyst or an iridium ruthenium catalyst; the top of the reaction kettle 1 is connected with a pipeline of a material flow 109 containing methyl iodide and CO;

the production plant further comprises a separation tank 6, a line for a stream 109 comprising methyl iodide and CO being connected to the separation tank 6 for separating the stream 109 comprising methyl iodide and CO, a stream 110 comprising CO being withdrawn from the top of the separation tank 6 for absorption or recovery means, and a stream 111 comprising methyl iodide being withdrawn from the bottom of the separation tank 6 being returned to the reaction vessel 1.

The acetic acid and catalyst containing stream 108 is connected to flash vessel 30 such that acetic acid and catalyst containing stream 108 is separated in flash vessel 30 and stream 116 comprising CO, acetic acid, methyl acetate, methyl iodide, catalyst and water withdrawn from the top of flash vessel 30 enters the middle or lower portion of light ends column 28; the stream 112 containing the catalyst at the bottom of the flash evaporator 30 is returned to the reaction vessel 1, preferably by the mother liquor pump 8, and the stream 129 containing acetic acid and catalyst is taken from the bottom of the light ends column 28 and connected to the flash evaporator 30, and the stream containing acetic acid and catalyst is returned to the bottom of the flash evaporator 30, further returned to the reaction vessel 1, and the stream 115 containing CO, methyl acetate, methyl iodide and water is taken from the top of the light ends column 28, and the stream 117 containing crude acetic acid is taken from the middle of the light ends column.

The production device comprises a delaminator 5, the top of the light component removal tower 28 is connected with the delaminator 5 through a pipeline, a material flow 103 containing water, methyl acetate and acetic acid separated from the delaminator 5 is respectively connected with the upper part of the light component removal tower 28 and the reaction kettle 1 through a pipeline, preferably is respectively connected with the upper part of the light component removal tower 28 and the reaction kettle 1 through a light component removal tower reflux pump 31, and a separated material flow 105 containing methyl iodide and methyl acetate is connected with the reaction kettle 1 through a pipeline, preferably is connected with the reaction kettle 1 through a heavy phase pump 13.

The line of stream 117 containing crude acetic acid is connected to dehydration column 3 for further separation of stream 117 containing crude acetic acid, preferably by connection to dehydration column 3 via dehydration column feed pump 15, stream 121 containing acetic acid and propionic acid is withdrawn from the bottom of dehydration column 3, stream 104 containing water, methyl iodide, methanol and methyl acetate is withdrawn from the top of dehydration column 3, preferably stream 104 is connected to dehydration column condenser/finishing column reboiler 21 and dehydration column reflux drum 20, and returned to the top of dehydration column 3 via dehydration column reflux pump 19, with the additional withdrawn portion of stream 104 being returned to reaction vessel 1;

connecting a pipeline of a stream 121 containing acetic acid and propionic acid with the finishing column 4 to further separate the stream 121 containing acetic acid and propionic acid in the finishing column 4, separating an acetic acid product 124 from the middle part of the finishing column 4, introducing a stream 122 containing water and acetic acid extracted from the top of the finishing column 4 into a finishing column condenser 22 to be condensed, and returning the stream to the finishing column 4 through a reflux drum 23, preferably through a finishing column reflux pump 24, and returning part of the stream 122 containing water and acetic acid to the dehydrating column 3, extracting a stream 125 containing propionic acid from the bottom of the finishing column 4;

the heat exchanger 21 is arranged on the finished product tower 4, and the tower top of the dehydrating tower 3 and the tower bottom of the finished product tower 4 are connected with the heat exchanger 21 through pipelines so as to take the steam at the tower top of the dehydrating tower 3 as a heat source of the tower bottom of the finished product tower 4.

FIG. 5 is a schematic diagram of an embodiment of the application, as shown in FIG. 5, the production plant comprising a reaction vessel 1, a flash column (not shown), a dehydration column 3 and a finishing column 4, the flash column comprising a flash vessel 30, a pre-wash column 29 and a light ends column 28, the reaction vessel 1 being connected to a line for CO stream 101 and a line for methanol stream 102 for feeding CO and methanol to the reaction vessel, the reaction vessel 1 being connected to a line for a stream 108 comprising acetic acid and a catalyst, the catalyst being a rhodium lithium iodide catalyst or an iridium ruthenium catalyst, to withdraw from the reaction vessel a stream 108 comprising acetic acid and a catalyst; the top of the reaction kettle 1 is connected with a pipeline of a material flow 109 containing methyl iodide and CO;

the production plant further comprises a separation tank 6, a line for a stream 109 comprising methyl iodide and CO being connected to the separation tank 6 for separating the stream 109 comprising methyl iodide and CO, a stream 110 comprising CO being withdrawn from the top of the separation tank 6, a means for absorption or recovery, and a stream 111 comprising methyl iodide withdrawn from the bottom of the separation tank 6 being returned to the reaction vessel 1.

The acetic acid and catalyst containing stream 108 is connected to the flasher 30 in a line such that the acetic acid and catalyst containing stream 108 is separated in the flasher 30, a stream 116 comprising CO, acetic acid, methyl acetate, methyl iodide, catalyst and water withdrawn from the top of the flasher 30 enters the lower section of the pre-wash column 29, a stream 131 comprising CO, acetic acid, methyl acetate, methyl iodide and water withdrawn from the top of the pre-wash column 29, a stream 129 comprising acetic acid and catalyst withdrawn from the bottom of the pre-wash column 29 is returned to the flasher 30, a line of the stream 131 comprising CO, acetic acid, methyl acetate, methyl iodide and water is connected to the middle or lower section of the light ends column 28 to further remove light ends from the stream comprising CO, acetic acid, methyl acetate, methyl iodide and water withdrawn from the top of the light ends column 28, a stream 130 comprising acetic acid and catalyst withdrawn from the bottom of the light ends column 28, a stream 129/130 comprising acetic acid and catalyst withdrawn from the bottom of the pre-wash column 29 is returned to the flasher 30, a stream comprising acetic acid and catalyst is returned to the bottom of the flasher 8, preferably a stream 112 from the bottom of the light ends column 30 is returned to the flash reactor 1.

The production device comprises a delaminator 5, and the top of the light component removal tower 28 is connected with the delaminator 5 through a pipeline; the stream 103 containing water, methyl acetate and acetic acid separated from the separator 5 is connected via a line to the upper part of the light ends removal column 28 and the reaction vessel 1, respectively, preferably via a light ends removal column reflux pump 31 to the upper part of the light ends removal column 28 and the reaction vessel 1, respectively, and the separated stream 105 containing methyl iodide and methyl acetate is connected via a line to the reaction vessel 1, preferably via a heavy phase pump 13 to the reaction vessel 1.

The line of stream 117 containing crude acetic acid is connected to dehydration column 3 for further separation of stream 117 containing crude acetic acid, preferably by connection to dehydration column 3 via dehydration column feed pump 15, stream 121 containing acetic acid and propionic acid is withdrawn from the bottom of dehydration column 3, stream 104 containing water, methyl iodide, methanol and methyl acetate is withdrawn from the top of dehydration column 3, preferably stream 104 is connected to dehydration column condenser/finishing column reboiler 21 and dehydration column reflux drum 20, and returned to dehydration column 3 via dehydration column reflux pump 19, with the additional withdrawn portion of stream 104 being returned to reaction vessel 1;

connecting a pipeline of a stream 121 containing acetic acid and propionic acid with the finishing column 4 to further separate the stream 121 containing acetic acid and propionic acid in the finishing column 4, separating an acetic acid product 124 from the middle part of the finishing column 4, introducing a stream 122 containing water and acetic acid extracted from the top of the finishing column 4 into a finishing column condenser 22 to be condensed, and returning the stream to the finishing column 4 through a reflux drum 23, preferably through a finishing column reflux pump 24, and returning part of the stream 122 containing water and acetic acid to the dehydrating column 3, extracting a stream 125 containing propionic acid from the bottom of the finishing column 4;

The heat exchanger 21 is arranged on the finished product tower 4, and the tower top of the dehydrating tower 3 and the tower bottom of the finished product tower 4 are connected with the heat exchanger 21 through pipelines so as to take the steam at the tower top of the dehydrating tower 3 as a heat source of the tower bottom of the finished product tower 4.

The dehydration tower 3 is provided with a reboiler 16, and the bottoms of the dehydration tower 3 and the middle part of the reaction kettle 1 are connected with the reboiler 16 through pipelines so as to supply the reaction heat or steam in the bottoms of the dehydration tower 3 and the middle part of the reaction kettle 1 to the dehydration tower 3.

According to the production device, as the heat exchanger is arranged in the finished product tower and the reboiler is arranged in the dehydration tower, the consumption of steam can be greatly reduced, and the purity of acetic acid can be further improved by adopting the partition rectifying tower in the finished product tower.

The application provides a method for synthesizing acetic acid by methanol low-pressure carbonylation by using the device, which comprises the following steps:

feeding the CO stream and the methanol stream into a reaction kettle for reaction to obtain a stream containing acetic acid and a catalyst, and extracting the stream containing the acetic acid and the catalyst from the reaction kettle;

the material flow containing acetic acid and catalyst enters a flash tower for separation, and a material flow containing crude acetic acid is extracted from the flash tower;

Feeding the material flow containing the crude acetic acid into a dehydration tower to separate the material flow containing the crude acetic acid, extracting the material flow containing acetic acid and propionic acid from the tower bottom of the dehydration tower, and extracting the material flow containing water, methyl iodide, methanol and methyl acetate from the tower top of the dehydration tower;

the material flow containing acetic acid and propionic acid enters into the finished product tower to separate the material flow containing acetic acid and propionic acid, acetic acid products are extracted from the middle part of the finished product tower, the material flow containing water and acetic acid is extracted from the top of the finished product tower, and the material flow containing propionic acid is extracted from the tower bottom of the finished product tower. In some embodiments, the stream comprising methyl iodide and CO and the stream withdrawn from the top of the flash column are passed to a separator for separation, and the stream comprising catalyst is withdrawn from the bottom of the flash column and returned to the reaction vessel. In some embodiments, the stream containing water, methyl acetate and acetic acid separated from the separator is fed to the upper portion of the flash column and to the reaction vessel, respectively, and the stream containing methyl iodide and methyl acetate is returned to the reaction vessel. In some embodiments, the stream comprising methyl iodide and CO is fed to a separator tank for separation, the stream comprising CO is withdrawn from the top of the separator tank and fed to a separator from the material withdrawn from the top of the flash column, and the stream comprising methyl iodide withdrawn from the bottom of the separator tank is returned to the reaction vessel.

In some embodiments, the dehydration column has a pressure of 120 to 500kpa, preferably 160 to 250 kpa; and/or

The temperature of the tower bottom of the dehydration tower is 140-200 ℃; and/or

The temperature of the top of the dehydration tower is 100-160 ℃; and/or

The number of the tower trays of the dehydration tower is 45-120; and/or

The pressure of the flash tower is 80-250KpaG, preferably 100-180KpaG; and/or

The temperature of the top of the flash tower is 80-150 ℃; and/or

The temperature of the tower bottom of the flash tower is 110-150 ℃.

For example, the dehydration column has a pressure of 120KpaG, 130KpaG, 140KpaG, 150KpaG, 160KpaG, 170KpaG, 180KpaG, 190KpaG, 200KpaG, 210KpaG, 220KpaG, 230KpaG, 240KpaG, 250KpaG, 300KpaG, 350KpaG, 400KpaG, 450KpaG, 500KpaG, etc.;

the temperature of the tower bottom of the dehydration tower is 140 ℃, 145 ℃, 150 ℃, 155 ℃, 160 ℃, 165 ℃, 170 ℃, 180 ℃, 190 ℃, 200 ℃ and the like;

the top temperature of the dehydration tower is 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, 135 ℃, 140 ℃, 145 ℃, 150 ℃, 155 ℃, 160 ℃ and the like;

the tray layer number of the dehydration tower is 45 layers, 50 layers, 55 layers, 60 layers, 65 layers, 70 layers, 75 layers, 80 layers, 85 layers, 90 layers, 95 layers, 100 layers, 105 layers, 110 layers, 115 layers, 120 layers and the like;

The pressure of the flash tower is 80KpaG, 90KpaG, 100KpaG, 110KpaG, 120KpaG, 130KpaG, 140KpaG, 150KpaG, 160KpaG, 170KpaG, 180KpaG, 190KpaG, 200KpaG, 210KpaG, 220KpaG, 230KpaG, 240KpaG, 250KpaG and the like;

the top temperature of the flash tower is 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, 135 ℃, 140 ℃, 145 ℃, 150 ℃ and the like;

the temperature of the tower bottom of the flash tower is 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, 135 ℃, 140 ℃, 145 ℃, 150 ℃ and the like.

In some embodiments, the pressure of the finishing column is from-99 to 70kpa g; and/or

The temperature of the tower bottom of the finished product tower is 80-140 ℃; and/or

The temperature of the top of the finished product tower is 50-130 ℃; and/or

The number of tower tray layers of the finished product tower is 50-150.

For example, the pressure of the finishing column is-99 KpaG, -90KpaG, -80KpaG, -70KpaG, -60KpaG, -50KpaG, 0KpaG, 10KpaG, 20KpaG, 30KpaG, 40KpaG, 50KpaG, 60KpaG, 70KpaG, etc.;

the temperature of the tower bottom of the finished product tower is 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, 135 ℃, 140 ℃ and the like;

The tower top temperature of the finished product tower is 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃ and the like;

the number of tray layers of the finished tower is 50 layers, 60 layers, 70 layers, 80 layers, 90 layers, 100 layers, 110 layers, 120 layers, 130 layers, 140 layers, 150 layers and the like.

In some embodiments, the internal components of the dehydration tower adopt a mode of filling materials on trays, preferably, the number of the trays is 45-120 layers, and the height of the filling materials is 0-30 m. In some embodiments, the internals of the finished column are trays filled, preferably with a number of trays ranging from 50 to 150 and a packing height ranging from 0 to 60 meters.

For example, the internals of the dehydration column are 45 layers +5 meters of packing, 45 layers +10 meters of packing, 45 layers +15 meters of packing, 50 layers +5 meters of packing, 50 layers +10 meters of packing, 55 layers +5 meters of packing, 55 layers +10 meters of packing, 60 layers +5 meters of packing, 60 layers +10 meters of packing, 65 layers +5 meters of packing, 65 layers +10 meters of packing, 70 layers +5 meters of packing, 70 layers +10 meters of packing, 80 layers +5 meters of packing, 80 layers +10 meters of packing, etc.;

the internals of the finished tower are 50 layers of +5 meter fillers, 50 layers of +10 meter fillers, 50 layers of +15 meter fillers, 55 layers of +5 meter fillers, 55 layers of +10 meter fillers, 60 layers of +5 meter fillers, 60 layers of +10 meter fillers, 65 layers of +5 meter fillers, 65 layers of +10 meter fillers, 70 layers of +5 meter fillers, 70 layers of +10 meter fillers, 75 layers of +5 meter fillers, 75 layers of +10 meter fillers, 80 layers of +5 meter fillers, 80 layers of +10 meter fillers, 85 layers of +5 meter fillers, 85 layers of +10 meter fillers, 90 layers of +5 meter fillers, 90 layers of +10 meter fillers, 95 layers of +5 meter fillers, 95 layers of +10 meter fillers, 100 layers of +5 meter fillers, 100 layers of +10 meter fillers and the like.

In some embodiments, the acetic acid product has a purity of 99.8 to 99.99%.

The acetic acid product prepared by the device has higher purity and the purity is more than 99.8 percent.

Examples

The materials used in the test and the test methods are described generally and/or specifically in the examples which follow,% represents wt%, i.e. weight percent, unless otherwise specified. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.

Example 1

The device shown in figure 1 is adopted to prepare an acetic acid product, wherein the pressure of a dehydration tower is 180KpaG, the temperature of the tower bottom of the dehydration tower is 160 ℃, the temperature of the tower top of the dehydration tower is 130 ℃, and the number of tower tray layers of the dehydration tower is 60; the pressure of the flash tower is 140KpaG, the temperature of the tower bottom of the flash tower is 135 ℃, the temperature of the tower top of the flash tower is 110 ℃, and the number of layers of tower trays of the flash tower is 15; the pressure of the finished product tower is-70 KpaG, the temperature of the tower bottom of the finished product tower is 115 ℃, the temperature of the tower top of the finished product tower is 83 ℃, the number of layers of trays of the finished product tower is 80, and the purity of an acetic acid product prepared by adopting the device is 99.85%;

Steam consumption was calculated as 30 ten thousand tons of acetic acid plant, 9m kcal of steam was consumed per hour.

Example 2

The apparatus described in example 1 was used to produce acetic acid product, unlike example 1, in which the finishing column used a dividing wall rectifying column in which the pressure of the dehydration column was 180kpa g, the column bottom temperature of the dehydration column was 160 ℃, the column top temperature of the dehydration column was 130 ℃, and the number of tray layers of the dehydration column was 60; the pressure of the flash tower is 140KpaG, the temperature of the tower bottom of the flash tower is 135 ℃, the temperature of the tower top of the flash tower is 110 ℃, and the number of layers of tower trays of the flash tower is 15; the pressure of the finished product tower is-70 KpaG, the temperature of the tower bottom of the finished product tower is 115 ℃, the temperature of the tower top of the finished product tower is 83 ℃, the number of layers of trays of the finished product tower is 80, and the purity of an acetic acid product prepared by adopting the device is 99.99%;

steam consumption was calculated as a 30 ten thousand ton acetic acid unit, with 9m kcal of steam consumed per hour.

Example 3

The apparatus shown in FIG. 3 was used to produce acetic acid product, wherein the dehydration column had a pressure of 190KpaG, a bottom temperature of 163℃and a top temperature of 135℃and the number of trays of 65 layers; the pressure of the flash tower is 130KpaG, the temperature of the tower bottom of the flash tower is 132 ℃, the temperature of the tower top of the flash tower is 105 ℃, and the number of layers of tower trays of the flash tower is 17; the pressure of the finished product tower is-60 KpaG, the temperature of the tower bottom of the finished product tower is 118 ℃, the temperature of the tower top of the finished product tower is 90 ℃, the number of layers of trays of the finished product tower is 78, and the purity of an acetic acid product prepared by adopting the device is 99.85%;

Steam consumption was calculated as 30 ten thousand tons of acetic acid plant, 9m kcal of steam was consumed per hour.

Example 4

The apparatus shown in FIG. 4 was used to produce acetic acid product, wherein the dehydration column had a pressure of 160KpaG, a column bottom temperature of 155℃and a column top temperature of 128℃and the number of trays in the dehydration column was 55; the pressure of the flash evaporator is 120KpaG, the temperature of the tower bottom of the flash tower is 130 ℃, the temperature of the tower top of the flash tower is 100 ℃, and the number of tower tray layers of the flash tower is 13; the pressure of the finished product tower is-80 KpaG, the tower bottom temperature of the finished product tower is 110 ℃, the tower top temperature of the finished product tower is 75 ℃, the number of layers of trays of the finished product tower is 70, and the purity of an acetic acid product prepared by adopting the device is 99.85%;

steam consumption was calculated for a 30 ten thousand ton acetic acid unit, with 10m kcal of steam consumed per hour.

Example 5

The apparatus shown in FIG. 5 was used to produce acetic acid product, wherein the dehydration column had a pressure of 170KpaG, a column bottom temperature of 158℃and a column top temperature of 133℃and the number of trays in the dehydration column was 60; the pressure of the flash evaporator is 130KpaG, the temperature of the tower bottom of the flash evaporator is 132 ℃, and the temperature of the tower top of the flash evaporator is 130 ℃; the pressure of the finished product tower is-90 KpaG, the temperature of the tower bottom of the finished product tower is 106 ℃, the temperature of the tower top of the finished product tower is 70 ℃, the number of layers of trays of the finished product tower is 90, and the purity of an acetic acid product prepared by adopting the device is 99.95%;

Steam consumption was calculated as 30 ten thousand tons of acetic acid plant, 9m kcal of steam was consumed per hour.

Comparative example 1

Comparative example 1 differs from example 1 in that the heat exchanger 21 was not provided in the final product column 4, and the purity of the acetic acid product obtained was 99.8%;

steam consumption was calculated as 30 ten thousand tons of acetic acid unit, with 20 mcal per hour of steam consumption.

The above description is only a preferred embodiment of the present application, and is not intended to limit the application in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present application still fall within the protection scope of the technical solution of the present application.

Claims (14)

1. A production apparatus for synthesizing acetic acid by methanol low-pressure carbonylation, comprising:

a reaction kettle, a flash evaporation tower, a dehydration tower and a finished product tower;

the reactor is connected to a line for the CO stream and a line for the methanol stream for feeding CO and methanol to the reactor,

the reaction kettle is used for carrying out a reaction between CO and methanol to obtain a material flow containing acetic acid and a catalyst;

The reaction kettle is connected with a pipeline of a material flow containing acetic acid and catalyst so as to extract the material flow containing acetic acid and catalyst from the reaction kettle;

the pipeline of the material flow containing the acetic acid and the catalyst is connected with a flash tower so that the material flow containing the acetic acid and the catalyst is separated in the flash tower, and a material flow containing the crude acetic acid is extracted from the flash tower;

a pipeline of the material flow containing the crude acetic acid is connected with a dehydration tower for further separating the material flow containing the crude acetic acid, the material flow containing the acetic acid and the propionic acid is extracted from the tower bottom of the dehydration tower, and the material flow containing water, methyl iodide, methanol and methyl acetate is extracted from the tower top of the dehydration tower;

connecting a pipeline of a material flow containing acetic acid and propionic acid with the finished product tower to further separate the material flow containing acetic acid and propionic acid in the finished product tower, separating an acetic acid product from the middle part of the finished product tower, extracting the material flow containing water and acetic acid from the top of the finished product tower, and extracting the material flow containing propionic acid from the tower bottom of the finished product tower.

2. The production apparatus according to claim 1, wherein the finishing column is provided with a heat exchanger, and the top of the dehydrating column and the bottom of the finishing column are connected to the heat exchanger through pipelines to use the vapor at the top of the dehydrating column as a heat source for the bottom of the finishing column.

3. The production apparatus according to claim 1 or 2, wherein the finishing column is a divided wall rectifying column.

4. A production apparatus according to any one of claims 1 to 3, wherein the dehydration column is provided with a reboiler, and a column bottom of the dehydration column and a middle portion of the reaction vessel are connected to the reboiler through a pipeline to supply reaction heat or steam of the column bottom of the dehydration column and the middle portion of the reaction vessel to the dehydration column.

5. The production apparatus according to any one of claims 1 to 4, wherein the top of the reaction vessel is connected to a line of a stream containing methyl iodide and CO.

6. The production apparatus according to claim 5, wherein the production apparatus comprises a layering device, the top of the flash column is connected with a pipeline of a stream containing methyl iodide and CO extracted from the top of the reaction kettle through a pipeline, and is connected with the layering device, and a stream containing the catalyst is extracted from the bottom of the flash column and returned to the reaction kettle.

7. The production apparatus according to claim 6, wherein the stream containing water, methyl acetate and acetic acid separated from the separator is connected to the upper part of the flash column and the reaction vessel through lines, respectively, and the stream containing methyl iodide and methyl acetate is connected to the reaction vessel through lines.

8. The production apparatus according to any one of claims 5 to 7, wherein the production apparatus comprises a separation tank to which a line for a stream containing methyl iodide and CO is connected for separating the stream containing methyl iodide and CO, a stream containing CO is withdrawn from the top of the separation tank, and a stream containing methyl iodide withdrawn from the bottom of the separation tank is returned to the reaction vessel with a material withdrawn from the top of the flash column being connected to a separator through a line.

9. A method of producing methanol low pressure oxo acetic acid using the production apparatus of any one of claims 1-8, comprising:

feeding the CO stream and the methanol stream into a reaction kettle for reaction to obtain a stream containing acetic acid and a catalyst, and extracting the stream containing the acetic acid and the catalyst from the reaction kettle;

the material flow containing acetic acid and catalyst enters a flash tower for separation, and a material flow containing crude acetic acid is extracted from the flash tower;

feeding the material flow containing the crude acetic acid into a dehydration tower to separate the material flow containing the crude acetic acid, extracting the material flow containing acetic acid and propionic acid from the tower bottom of the dehydration tower, and extracting the material flow containing water, methyl iodide and methyl acetate from the tower top of the dehydration tower;

The material flow containing acetic acid and propionic acid enters into the finished product tower to separate the material flow containing acetic acid and propionic acid, acetic acid products are extracted from the middle part of the finished product tower, the material flow containing water and acetic acid is extracted from the top of the finished product tower, and the material flow containing propionic acid is extracted from the tower bottom of the finished product tower.

10. The process of claim 9, wherein a stream comprising methyl iodide and CO is withdrawn from the top of the reaction vessel.

11. A process according to claim 9 or claim 10 wherein the stream comprising methyl iodide and CO and the stream withdrawn from the top of the flash column are passed to a separator for separation and the stream comprising catalyst is withdrawn from the bottom of the flash column and returned to the reactor.

12. The process of claim 11, wherein the stream containing water, methyl acetate and acetic acid separated from the separator is fed to the upper portion of the flash column and the reaction vessel, respectively, and the stream containing methyl iodide and methyl acetate is fed back to the reaction vessel.

13. The process according to any one of claims 10-12, wherein the stream comprising methyl iodide and CO is fed to a separation tank for separation, the stream comprising CO is withdrawn from the top of the separation tank and fed to a separator from the material withdrawn from the top of the flash column, and the stream comprising methyl iodide withdrawn from the bottom of the separation tank is returned to the reaction vessel.

14. The process according to any one of claims 9-13, wherein the pressure of the dehydration column is 120-500kpa g, preferably 160-250kpa g; and/or

The temperature of the tower bottom of the dehydration tower is 140-200 ℃; and/or

The temperature of the top of the dehydration tower is 100-160 ℃; and/or

The number of the tower trays of the dehydration tower is 45-120; and/or

The pressure of the flash tower is 80-250KpaG, preferably 100-180KpaG; and/or

The temperature of the top of the flash tower is 80-150 ℃; and/or

The temperature of the tower bottom of the flash tower is 110-150 ℃; and/or

The pressure of the finished product tower is-99 to 70KpaG; and/or

The temperature of the tower bottom of the finished product tower is 80-140 ℃; and/or

The temperature of the top of the finished product tower is 50-130 ℃; and/or

The number of tower tray layers of the finished product tower is 50-150; and/or

The purity of the acetic acid product is 99.8-99.99%.