RU2800387C1 - Device and method for purifying esters - Google Patents

Abstract

FIELD: organic chemistry and esters.

SUBSTANCE: device for removing volatile impurities from crude ether is described, which is a column consisting of three sections, characterized in that the upper section is an apparatus equipped with a mass transfer device in the middle part of this apparatus, a spray device for supplying crude ether in the upper part of the apparatus and a device supply of live steam in the lower part of the apparatus; the middle section is a separator for separating two immiscible liquids with different specific gravity; the lower section is a stripping cube, and between the upper and middle sections, as well as between the middle and lower sections, solid partitions are installed, and wherein the upper and middle sections are connected to each other by a liquid pipeline and a steam pipeline, and also the middle and lower sections are connected to each other the other with a steam and liquid pipeline, and the middle section is additionally equipped with a side fitting for removal of water condensate. A method for purifying crude ether using the apparatus described above is described.

EFFECT: increase in the efficiency of purification of ethers from alcohol impurities and moisture, a simplification of the design of the device for purification.

36 cl, 3 dwg, 1 tbl, 5 ex

Description

The field of technology to which the invention belongs

The present invention relates to organic chemistry, in particular, to the field of obtaining esters used as plasticizers in various industries. The invention relates to a device for removing volatile impurities from crude ether and a method for removing volatile impurities from crude ether using this device.

State of the art

Esters of carboxylic acids and alcohols are widely used as plasticizers in various industries. For example, esters of benzoic or terephthalic acids and alcohols are used as plasticizers for PVC compositions, as well as in the production of adhesives, sealants, and varnishes.

One of the stages in the production of esters is the removal of volatile impurities from the crude ether, which reduce the quality of the commercial ester. So, for example, the presence of moisture residues in the commercial ether leads to a deterioration in the compatibility of the PVC resin with the plasticizer, and the presence of alcohol residues in the plasticizer leads to an undesirable odor and an increase in the flammability of the material.

Methods are known in the art for removing residual moisture and alcohol from crude ether. Thus, from the document EP 3511314 A (LG CHEMICAL, 07/17/2019), the use of distillation columns for the removal of alcohol and water is known, however, the structure of the columns and the characteristics of the final product are not disclosed in the document.

Also from the prior art, in particular from the document CN104341301 A (CHANGZHOU SONGSHENG PERFUMERY CO LTD, February 11, 2015), the use of drying agents (adsorbents) is known. However, this method of removing water from crude ether requires a large amount of drying agent, as well as time to unload the spent agent, drain the column and load a new batch of agent. In addition, after the drying agent has been exhausted, additional operations are required for its regeneration or disposal.

Closest to the proposed method is the method described in document CN105330539 A (ZIBO BLUE SAIL CHEMICAL CO LTD, 02/17/2016). According to this document, the removal of alcohol and water residues from the crude ether - dioctyl terephthalate - is continuously carried out using a device consisting of a stripping column and a heat exchanger. Crude ether is fed to the top of the column, operating at a temperature of 50°C and a pressure of 50 mbar. Water and alcohol evaporate, ether and residual amounts of water and alcohol enter the heat exchanger, where previously unevaporated water and alcohol evaporate and pass back into the stripping column. This method requires the use of a high level of vacuum, which complicates the design of the stripper. In addition, when implementing this method, volatile substances are carried away with the vapor phase into the vacuum pump, which also complicates the design of the vacuum pump. Also, this method is characterized by low water removal efficiency under the above conditions, since the difference between the boiling point of water at 50 mbar and the process temperature is less than 20°C.

Disclosure of the Invention

The objective of the present invention is to develop a device that allows continuous production of esters with a reduced content of volatile impurities and has a simple design, as well as an effective method for purifying crude ester from volatile impurities.

The technical result of the present invention is to obtain an ester with a residual moisture content of 0.05 wt.% or less and an alcohol content of 0.05 wt.% or less with high efficiency without the use of devices that have a complex design and require the use of low pressures (high vacuum) and drying agents.

An additional technical result is the possibility of cleaning plasticizers with different densities on a continuously operating device.

The problem is solved and the technical result is achieved by providing a device for removing volatile impurities from crude ether, which is a column consisting of three sections, characterized in that:

- the upper section is an apparatus equipped with a mass transfer device in the middle part of this apparatus, a spray device for supplying crude ether in the upper part of the apparatus and a live steam supply device in the lower part of the apparatus;

- the middle section is a separator for separating two immiscible liquids with different specific gravity;

- the lower section is a distillation cube,

moreover, between the upper and middle sections, as well as between the middle and lower sections, solid partitions are installed, and at the same time, the upper and middle sections are connected to each other by a liquid pipeline and a steam pipeline, and the middle and lower sections are connected to each other by a steam pipeline and a liquid pipeline, and the middle section is additionally equipped with a side fitting for removing water condensate,

and also by providing a method for purifying crude ether, including distillation of crude ether in a column-type apparatus, characterized in that said column-type apparatus consists of three sections:

the upper section (hereinafter also referred to as mass transfer) is an apparatus provided with a mass exchange device in the middle part of this apparatus, a spray device in the upper part of the apparatus, and a live steam supply device in the lower part of the apparatus;

the middle section (hereinafter also referred to as the separation section) is a separator used to separate two immiscible liquids with different specific gravity;

the lower section (hereinafter also referred to as the evaporator) is a distillation cube,

moreover, between the upper and middle sections, as well as between the middle and lower sections, solid partitions are installed, and at the same time, the upper and middle sections are connected to each other by a liquid pipeline and a steam pipeline, and the middle and lower sections are connected to each other by steam pipelines and liquid pipelines, and the middle section is additionally equipped with a side fitting for removing water condensate,

wherein the crude ether is supplied to the upper part of the upper section through the aforementioned spray device, live steam is supplied to the lower part of the upper section through the said live steam supply device, the liquid from the upper section enters the middle section through the liquid pipeline connecting the upper and middle sections, the ether separated from water enters from the middle section into the lower section through the liquid pipeline connecting the middle and lower sections. The water condensate is discharged through the mentioned side fitting of the middle section. The product is withdrawn from the bottom of the lower section. Residual vapors are removed from the upper part of the upper section of said column type apparatus.

The inventors of the present invention have unexpectedly found that in the case of using the apparatus described above, the crude ether steam purification process is more efficient. In this case, the formation of water condensate compensates for heat losses on the shell of the device. The condensate can be effectively separated from the ether in the separation section and reused in the purification process, for example, for washing the ether. Consequently, the apparatus does not require the installation of a steam jacket to compensate for heat losses, which greatly simplifies the design of the apparatus and reduces its material and resource consumption. The requirements for the design of the vacuum pump are also softened, for example, it becomes possible to use a water ring pump.

Description of figures

To explain the technical solutions that reveal the essence of the present invention are presented in Fig. 1-3:

Figure 1 shows a column apparatus, consisting of three sections, according to the invention, where: I - crude ether, II - live steam, III - water, IV - coolant, V - steam, VI - purified ether (product), 1 - check valve, 2 - three-way valve.

Figure 2 shows a sketch of a separator with a switched three-way valve for separating light ether from water, where: I - overflow, 1a, 1b - valves, 2 - three-way valve, 3 - phase separation control.

Figure 3 shows a sketch of a separator with a switched three-way valve for separating heavy ether from water, where: I - overflow, 1a, 1b - valves, 2 - three-way valve, 3 - phase separation control.

Detailed description of the invention

The device for removing volatile impurities according to the present invention is a column-type apparatus, consisting of three sections.

A) Upper section - mass transfer.

The upper part of the mass transfer section is provided with a spray device for supplying and spraying crude ether. The design of the spray device can be selected from the following options: a spray nozzle (FullJet, SPIRALJET brands) or a disk sprayer (devices according to RU 2278743 C1 (All-Russian Research Institute of Starch Products, June 27, 2006), RU 2513403 C1 (Oleg Savelyevich Kochetov, Maria Olegovna Stareeva, Maria Mikhailovna Stareeva, 04/20/2014), a perforated pipe of arbitrary geometry and other spray devices known from the prior art. The spray device allows you to increase the area of evaporation of volatile impurities.

In one of the preferred embodiments of the invention, the top of the mass transfer section is provided with a moisture separator and/or a moisture trap and/or a mist eliminator to prevent liquid from entering the vapors discharged from the top of the top section.

The middle part of the mass transfer section is equipped with a mass transfer device that allows efficient mixing of the liquid and vapor phases. The mass transfer device consists of mass transfer elements and/or trays known from the prior art. Packing or trays are used as mass transfer elements, preferably regular or irregular packing is used, most preferably irregular packing is used. Raschig rings, spiral prismatic packing are preferably used as irregular packing. As plates, mesh, cap and other plates known from the prior art are used.

The lower part of the mass transfer section is provided with a live steam supply device (not shown in the drawing) under the mass transfer device. As a live steam supply device, devices known from the prior art are used, for example: spray nozzles (FullJet, SPIRALJET brands) or disk sprayers (devices according to RU 2278743 C1 (All-Russian Research Institute of Starch Products, 06/27/2006), RU 2513403 C1 (Oleg Savelevich Kochetov, Maria Olegovna Stareeva, Maria Stareeva Mikhailovna, 04/20/2014), perforated pipes of arbitrary geometry and other devices known from the prior art

In embodiments of the device according to the invention, the height of the mass transfer section is chosen so that it is from 5 to 20 diameters of the shell of the apparatus, a more preferred ratio of height to diameter is from 10 to 15 to 1.

B) The middle - separation section can be a vertical cylindrical apparatus with a vertical baffle, which serves to separate two immiscible liquids with different specific gravity and a gas-vapor mixture.

In preferred embodiments, a three-way valve is installed on the liquid line connecting the separation section to the mass transfer section, allowing liquid to be directed from the upper section to the middle section, either from one or the other part of the vertical baffle. At the same time, a check valve is installed on the steam pipeline connecting the middle section with the upper section, which prevents the ingress of liquid from the upper section into the middle section through the steam pipeline. This makes it possible to carry out in the device according to the invention the purification of plasticizers with different densities, i.e. having a density both above the density of water (heavy ether) and below it (light ether), without stopping the equipment. The separation of such liquids is achieved by switching a three-way valve and subsequent gravity separation of the liquids in the separator, as shown in FIG. 2-3.

In preferred embodiments, the flow of fluid from the upper section to the middle section and/or from the middle section to the lower section is controlled by control devices, where valves, cocks and other shutoff devices known from the prior art are used as the control device.

In embodiments of the device according to the invention, the height of the separation section is chosen so that it is from 1 to 5 diameters of the shell of the apparatus, a more preferred ratio of height to diameter is from 1.5 to 2.5 to 1.

In embodiments of the device according to the invention, the height of the partition is chosen so that it is from 0.1 to 0.9 of the height of the section, a more preferred ratio of the height of the partition to the height of the section is from 0.6 to 0.8 to 1.

Structurally, the partition can be made in the form of a vertical flat solid wall, as shown in Fig. 2 and 3, or in the form of an overflow pipe connected to the bottom section.

Water condensate is discharged from the separation section through the side fittings installed in it, the product is drained into the bottom section, and excess vapors are removed to the mass transfer section through the steam pipeline connecting the separation section and the mass transfer section.

The removal of water condensate and the discharge of the product can be carried out both continuously and periodically. Other operations are carried out continuously. In this case, any device known from the prior art for monitoring the level of phase separation can be used to determine the need to remove water condensate.

The separation section is connected to the mass transfer section and the bottom section by steam pipelines. In one of the embodiments of the invention, a check valve can be installed on the steam line between the middle and top sections, preventing the ingress of liquid from the top section through the steam line into the middle and bottom sections.

In preferred embodiments of the invention, the separation section is equipped with liquid level sensors, where the sensors used are known from the prior art conductometric, float and other sensors.

C) The bottom section is a stripping cube of a prior art design. It can be provided with heat exchange elements known from the prior art. Built-in or remote heat exchangers can be used as heat exchange elements, preferably built-in tubular or shell-and-tube heat exchangers are used. In the case of using a remote heat exchanger, the heated flow can be directed to the bottom section through a circulation pump and/or a spray device. The design of the spray device can be selected from the following options: a spray nozzle (FullJet, SPIRALJET brands) or a disk sprayer (devices according to RU 2278743 C1 (All-Russian Research Institute of Starch Products, June 27, 2006), RU 2513403 C1 (Oleg Savelyevich Kochetov, Maria Olegovna Stareeva, Maria Mikhailovna Stareeva, 04/20/2014), a perforated pipe of arbitrary geometry and other spray devices known from the prior art.

To further intensify the evaporation of light impurities and create an inert atmosphere, a gas inert with respect to the product can be supplied to the lower section through the distribution device at a rate of 0.01 to 1 volume of the mass transfer section per hour, more preferably from 0.1 to 0.5 volume of the mass transfer section per hour. As an inert gas, nitrogen, argon, helium, carbon monoxide, hydrocarbons or a mixture of the above compounds can be used. As a distribution device, devices similar to those described above for spray devices can be used.

The material of the device elements is selected from among the materials inert to the components of the environment. As examples of inert materials, for example, low-alloyed (for example, grade 09G2S), stainless steels (for example, grades 08X18H10, 12X18H10T, AISI 304, AISI 316), glass (for example, quartz or borosilicate), plastic (for example, polycarbonate, fluoroplast, silicone rubber), graphite.

The device of the present invention is designed to remove volatile components from plasticizers, in particular from esters and polyesters formed by the interaction of carboxylic acids and alcohols, including polybasic acids and polyhydric alcohols.

In one of the preferred embodiments of the invention, the esters to be purified by the claimed method are formed by reacting aliphatic alcohols containing from 4 to 12 carbon atoms with organic acids containing from one to 4 carboxyl groups.

The crude ether can be obtained by any method known in the art. Examples of production methods include, but are not limited to, the methods described in: WO2019059801 A1 (SIBUR, 03/28/2019), WO2019059800 A1 (SIBUR, 03/28/2019), WO2019066671 A1 (SIBUR, 04/04/2019), US9388293 B1 ( EASTMAN CHEM CO, 07/12/2016), US7361779 B1 (US7361779, 04/22/2008).

In one of the preferred embodiments, the process for removing low-boiling impurities from crude ether includes the following steps:

- crude ether containing up to 50 wt.% alcohol, a more preferred ratio of alcohol content up to 20 wt.%, and 5 wt.% water, a more preferred ratio of water content up to 2 wt.% with a temperature of 160-200 ° C is fed as raw material to the upper part of the mass transfer section of the column (section "A", Fig. 1 stream I) by spraying crude ether through a spray device;

- live steam with a temperature of 140-180°C is fed countercurrently into the lower part of the mass transfer section (section "A", Fig. 1, flow II);

- to compensate for the hydraulic resistance of the liquid column on the mass transfer devices, the pressure in the upper part of the mass transfer section is maintained below 1000 mbar, while the pressure value depends on the height of the mass transfer layer, the parameters of the mass transfer devices and varies in the range from 200 to 900 mbar, the interval from 400 to 700 mbar is preferable. It is obvious to a specialist in this field of technology that the process can be carried out at a pressure above atmospheric pressure, but the temperature range should be shifted upwards;

- the ether purified from alcohol enters the separation section of the column through a liquid pipeline connecting the upper section with the middle section (section "B", Fig. 1), in which water is separated from the ether (Fig. 2 and 3);

- through a liquid pipeline connecting the middle section with the lower section, the ether separated from water enters the lower section of the column (section "B", Fig. 1), in which it is heated to a temperature of 160-200 ° C, where the remaining volatile compounds are distilled off. The distilled vapors through the steam pipeline connecting the lower section with the middle section enter the separation part of the column (section "B", Fig. 1), in which they are partially condensed. Residual vapors through the steam line connecting the middle section with the upper section are removed to the mass transfer section of the column (section "A", Fig. 1) and then removed from the upper part of the apparatus of the column type according to the invention. Purified ether is removed from the bottom of the cubic section.

To further increase the efficiency of purification of esters (obtaining a product with a reduced content of volatile impurities and an acceptable moisture level), the claimed method, in which live steam is supplied to the lower part of the upper section, is preferably carried out at a mass ratio of live steam/crude ether from 0.1:2 to 2:0.1, preferably from 1:2 to 2:1.

Implementation of the invention

The residual alcohol content in the product was determined by gas chromatography on an Agilent 7890B chromatograph, DB35 column, FID.

The residual water content was determined by Karl-Fischer titration.

Example 1. Continuous process. Crude ether, which is a mixture of dioctyl terephthalate and 2-ethylhexanol, is fed into the upper part of the mass transfer section of the purification column, 2.5 meters high, at a rate of 10 kg per hour at a temperature of 180°C. Countercurrent into the lower part of the mass transfer section of the purification column serves live steam at a rate of 5 kg per hour and a temperature of 150°C. The process is carried out at a pressure of 500 mbar in the upper section and a temperature in the bottom section of 180°C. The pressure in the lower section is 650 mbar. Purified from alcohol, the plasticizer is passed through the separation section into the cubic section. 1 liter of water per hour is removed from the separation section. Finished plasticizer is removed from the bottom section. Residual vapors are removed from the top of the purification column.

Example 2. The process is carried out under the conditions of example 1, but, unlike example 1, the mass ratio of live steam to raw ether is 1:1 at a steam rate of 10 kg per hour.

Example 3. The process is carried out under the conditions of example 1, but, unlike example 1, the mass ratio of live steam to raw ether is 2:1 at a steam rate of 20 kg per hour.

Example 4 (Comparative). The process is carried out under the conditions of example 2, but, unlike example 2, the plasticizer purified from alcohol is passed, bypassing the separation section, into the cubic section.

Example 5 (Comparative). periodic process. The process is carried out in a periodically operating capacitive apparatus, equipped with a mixing device and a vapor outlet. 1 liter of crude ether, which is a mixture of dioctyl terephthalate and 2-ethylhexanol, is poured into a 2-liter apparatus. Water vapor is bubbled through the contents of the apparatus at a rate of 200 grams per hour and a temperature of 150°C. The process is carried out with stirring at 100 rpm, a pressure of 500 mbar and a plasticizer temperature of 150°C for 5 hours. Once every half an hour, the residual alcohol content is determined.

The characteristics of the crude ester and the resulting product (plasticizer) are shown in Table 1.

Table 1 - Product Features

experiment number Feed rate
hot steam, kg/h Ratio sharp
steam/crude ether, wt.% Content
2-ethylhexanol in crude, wt.% Humidity raw, wt.% Content
2-ethylhexanol in the product, wt.% product moisture,
wt.% Example 1 5 1:2 15 1.5 0.1 0.01 Example 2 10 1:1 0.05 0.03 Example 3 20 2:1 0.01 0.05 Example 4 10 1:1 0.05 1.0 Example 5 0.2* 1:1 6.4 0.01

* value for 1 hour.

The total cleaning time was 5 hours.

As can be seen from Table 1, the removal of volatile compounds from crude ether in a device containing three sections, allows you to effectively remove residual water and unreacted alcohol from the mass of ether (examples 1-3).

The device, which contains only the mass transfer section and the still, allows you to effectively remove the alcohol, however, the residual amount of water is large.

Removal of volatile impurities from crude ether using a capacitive apparatus (example 5) is time-consuming and very energy-intensive. Such a batch process effectively removes water, but the amount of alcohol remains very high.

However, one skilled in the art will appreciate that the ranges and exact values of the parameters will depend on the particular substance (ie, boiling point and azeotrope composition, etc.).

Claims (45)

1. A device for removing volatile impurities from crude ether, which is a column consisting of three sections, characterized in that: - the upper section is an apparatus equipped with a mass transfer device in the middle part of this apparatus, a spray device for supplying crude ether in the upper part of the apparatus and a live steam supply device in the lower part of the apparatus; - the middle section is a separator for separating two immiscible liquids with different specific gravity; - the lower section is a distillation cube, moreover, between the upper and middle sections, as well as between the middle and lower sections, solid partitions are installed, and at the same time, the upper and middle sections are connected to each other by a liquid pipeline and a steam pipeline, and also the middle and lower sections are connected to each other by a steam pipeline and a liquid pipeline, and the middle section is additionally equipped with a side fitting for removing water condensate. 2. The device according to claim. 1, in which the mass transfer device consists of mass transfer elements, while the mass transfer elements are a nozzle or plates. 3. An apparatus according to claim 1 or 2, wherein the nozzle is a regular or irregular nozzle, preferably an irregular nozzle. 4. The apparatus of claim 3 wherein the irregular packing is a Raschig ring or a spiral prism packing. 5. The device according to any one of paragraphs. 1-4, wherein the height of the upper section is 5 to 20 device shell diameters, preferably 10 to 15 device shell diameters. 6. The device according to any one of paragraphs. 1-5, in which the separation section is a vertical cylindrical separator with a vertical baffle. 7. The device according to claim 6, in which a three-way valve is located on the liquid pipeline connecting the middle section with the upper section, installed in such a way that it allows directing liquid from the upper section to the middle section either on one side of the vertical partition or on the other side of the vertical partition, and a check valve is installed on the steam pipeline connecting the middle section with the upper section. 8. The device according to any one of paragraphs. 1-7, in which the height of the separation section is from 1 to 5 diameters of the shell of the device, more preferably the ratio of the height of the separation section to the diameter of the shell of the device is from 1.5 to 2.5 to 1. 9. The device according to any one of paragraphs. 6-8, in which the height of the vertical baffle of the separation section is from 0.1 to 0.9 of the height of the separation section, more preferably the ratio of the height of said baffle to the height of the separation section is from 0.6 to 0.8 to 1. 10. The device according to any one of paragraphs. 6-9, in which the vertical partition is made in the form of a vertical flat solid wall or in the form of an overflow pipe connected to the bottom section. 11. The device according to any one of paragraphs. 1-10, in which the lower section is provided with heat exchange elements. 12. The device according to claim 11, wherein the heat exchange elements are built-in or remote heat exchangers, preferably built-in tubular or shell-and-tube heat exchangers. 13. The device according to any one of paragraphs. 1-12, in which the lower section is additionally provided with a distribution device for introducing an inert gas. 14. A method for purifying crude ether, including distillation of crude ether in a column-type apparatus, characterized in that said column-type apparatus consists of three sections: - the upper section is an apparatus equipped with a mass transfer device in the middle part of this apparatus, a spray device for supplying crude ether in the upper part of the apparatus and a live steam supply device in the lower part of the apparatus; - the middle section is a separator for separating two immiscible liquids with different specific gravity; - the lower section is a distillation cube, moreover, between the upper and middle sections, as well as between the middle and lower sections, solid partitions are installed, and at the same time, the upper and middle sections are connected to each other by a liquid pipeline and a steam pipeline, and the middle and lower sections are connected to each other by a steam pipeline and a liquid pipeline, and the middle section is additionally equipped with a side fitting for removing water condensate, in this case, crude ether is supplied to the upper part of the upper section through the aforementioned spray device, live steam is supplied to the lower part of the upper section through the said live steam supply device, liquid from the upper section enters the middle section through a liquid pipeline connecting the upper and middle sections, ether separated from water enters from the middle section into the lower section through a liquid pipeline connecting the middle and lower sections, water condensate is removed through the said side fitting, the product is removed from the lower part of the lower section, and the residual vapor is removed from the upper part of the upper section said apparatus of the column type. 15. The method according to claim 14, in which the mass transfer device consists of mass transfer elements, while the mass transfer elements are nozzles or plates. 16. The method according to any one of paragraphs. 14 or 15, wherein the nozzle is a regular or irregular nozzle, preferably an irregular nozzle. 17. The method of claim 16, wherein the irregular packing is Raschig rings or spiral prismatic packing. 18. The method according to any one of paragraphs. 14-17, wherein the height of the upper section is 5 to 20 device shell diameters, preferably 10 to 15 device shell diameters. 19. The method according to any one of paragraphs. 14-18, in which the separation section is a vertical cylindrical separator with a vertical baffle. 20. The method according to claim 19, in which a three-way valve is located on the liquid pipeline connecting the middle section with the upper section, installed in such a way that it allows directing liquid from the upper section to the middle section either on one side of the vertical partition or on the other side of the vertical partition, and a check valve is installed on the steam pipeline connecting the middle section with the upper section. 21. The method according to any one of paragraphs. 14-20, in which the height of the separation section is from 1 to 5 diameters of the shell of the device, more preferably the ratio of the height of the separation section to the diameter of the shell of the device is from 1.5 to 2.5 to 1. 22. The method according to any one of paragraphs. 19-21, in which the height of the vertical baffle of the separation section is from 0.1 to 0.9 of the height of the separation section, more preferably the ratio of the height of said baffle to the height of the separation section is from 0.6 to 0.8 to 1. 23. The method according to any one of paragraphs. 19-22, in which the vertical partition is made in the form of a vertical flat solid wall or in the form of an overflow pipe connected to the bottom section. 24. The method according to any one of paragraphs. 14-23, in which the lower section is provided with heat exchange elements. 25. The method of claim. 24, in which the heat exchange elements are built-in or remote heat exchangers, preferably built-in tubular or shell-and-tube heat exchangers. 26. The method according to any one of paragraphs. 14-25, in which crude ether is fed into the device at an ether temperature of 160-200°C. 27. The method according to any one of paragraphs. 14-26, in which live steam is supplied at a temperature of 140-180°C. 28. The method according to any one of paragraphs. 14-27, in which the pressure in the upper section is below 1000 mbar. 29. The method according to any one of paragraphs. 14-28, in which the upper section operates in bubbling mode at a pressure in the range from 200 to 900 mbar and more preferably from 400 to 700 mbar. 30. The method according to any one of paragraphs. 14-29, in which the ether in the lower section is heated to 160-200°C. 31. The method according to any one of paragraphs. 14-30, further comprising the step of supplying a product-inert gas through a distribution device to the lower section at a rate of 0.01 to 1 mass transfer section volume per hour, more preferably 0.1 to 0.5 mass transfer section volume per hour. 32. The process of claim 31, wherein the product-inert gas is selected from the group consisting of nitrogen, argon, helium, carbon monoxide, hydrocarbons, or mixtures thereof. 33. The method according to any one of paragraphs. 14-32, in which the ester to be purified is selected from the group consisting of esters and polyesters formed by the reaction of carboxylic acids and alcohols, in particular polybasic acids and polyhydric alcohols. 34. The method according to any one of paragraphs. 14-33, in which the ester to be purified is formed by reacting aliphatic alcohols containing from 4 to 12 carbon atoms with organic acids containing from 1 to 4 carboxyl groups. 35. The method according to any one of paragraphs. 14-33, wherein the ether to be purified contains up to 50 wt. % alcohol, more preferably up to 20 wt. % alcohol, and 5 wt. % water, more preferably up to 2 wt. % water. 36. The method according to any one of paragraphs. 14-33, in which live steam is fed into the lower part of the upper section at a mass ratio of live steam/crude ether from 0.1:2 to 2:0.1, preferably from 1:2 to 2:1.

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