Energy-saving device and separation method for separating ethylene glycol mixture

Abstract

The present invention discloses an energy-saving device and separation method for separating an ethylene glycol mixture, and specifically relates to the technical field of energy conservation and emission reduction in chemical processes. The device comprises a high-pressure tower, a medium-pressure tower, a low-pressure tower and a first separation tower. The overhead steam of the high-pressure tower serves as a heating heat source for the medium-pressure tower, and the overhead steam of the medium-pressure tower serves as a heating heat source for the low-pressure tower. The mixed alcohol separation system comprises a first separation tower and a second separation tower, and the overhead steam of the low-pressure tower serves as a heating heat source for the first separation tower. The ethylene glycol mixture is subjected to a triple-effect distillation process, and more than 80% of the water in the ethylene glycol mixture can be removed. The distillation system fully utilizes the latent heat of the overhead steam, reduces the required external heat source, can save steam consumption, and has significant economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conservation and emission reduction in chemical processes, and in particular to an energy-saving device and a separation method for separating an ethylene glycol mixture. Background Art

[0002] Ethylene glycol is an important chemical raw material widely used in the chemical, pharmaceutical, and food industries. During the production process, ethylene glycol mixtures are typically distilled to obtain high-purity ethylene glycol products. However, due to the high water content and complex composition of ethylene glycol mixtures, separation via conventional distillation is difficult. Traditional ethylene glycol distillation methods suffer from high energy consumption, complex equipment, and high operating costs.

[0003] Since the ethylene glycol mixture has the characteristic of high water content, the distillation separation process of water consumes the most energy. The Chinese patent with publication number CN202210220436.6 discloses an energy-saving device and separation method for separating a mixture containing ethylene glycol. Specifically, it is disclosed that the ethylene glycol mixture is transported to a dehydration tower, heated by a reboiler at the bottom of the tower, the steam at the top of the tower is condensed by a condensing unit, water is produced at the top of the tower, and concentrated liquid is produced in the bottom of the tower. However, the ethylene glycol mixture only distills 99.9% of the water in a dehydration tower of the ethylene glycol mixture, and the required energy consumption is high, which further increases the cost of ethylene glycol distillation. Summary of the Invention

[0004] The purpose of the present invention is to provide an energy-saving device and separation method for separating ethylene glycol mixtures to solve the problems existing in the above-mentioned prior art, which can save the consumption of heating steam, have low overall energy consumption and simple process.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides an energy-saving device for separating an ethylene glycol mixture, comprising a distillation system and a mixed alcohol separation system;

[0007] The distillation system includes a high-pressure tower, a medium-pressure tower, a low-pressure tower, a first reboiler, a second reboiler and a third reboiler. The high-pressure tower is connected to the ethylene glycol mixture feed line, the first reboiler is connected to the heating steam feed line, and the heating steam enters the first reboiler as the heat source of the first reboiler. The tower bottom outlet pipeline of the high-pressure tower is divided into two. The material of one line is reboiled in the first reboiler and then refluxed to the high-pressure tower, and the other line is connected to the medium-pressure tower. The top of the high-pressure tower is connected to the second reboiler, and the top steam of the high-pressure tower is used as the heat source. The heat source of the second reboiler enters the second reboiler, the tower bottom outlet pipeline of the medium-pressure tower is divided into two, the material of one line is reboiled in the second reboiler and then refluxed to the medium-pressure tower, and the other line is connected to the low-pressure tower, the top of the medium-pressure tower is connected to the third reboiler, and the overhead steam of the medium-pressure tower enters the third reboiler as the heat source of the third reboiler, the tower bottom outlet pipeline of the low-pressure tower is divided into two, the material of one line is reboiled in the third reboiler and then refluxed to the low-pressure tower, and the other line is connected to the mixed alcohol separation system;

[0008] The mixed alcohol separation system includes a first separation tower, a second separation tower, a fourth reboiler and a fifth reboiler. The bottom of the low-pressure tower is connected to the first separation tower, and the top of the low-pressure tower is connected to the fourth reboiler. The overhead steam of the low-pressure tower enters the fourth reboiler as a heat source for the fourth reboiler. Water is produced from the top of the first separation tower, and ethylene glycol is produced from the side line of the first separation tower. The bottom outlet pipeline of the first separation tower is divided into two. The material of one line is reboiled in the fourth reboiler and then refluxed to the first separation tower, and the other line is connected to the second separation tower. The fifth reboiler is connected and connected to the lower part of the second separation tower. The fifth reboiler is connected to and connected to the heating steam feed line. The heating steam enters the fifth reboiler as a heat source for the fifth reboiler. Diethylene glycol is produced from the top of the second separation tower. The bottom outlet pipeline of the second separation tower is divided into two. The material of one line is reboiled in the fifth reboiler and then refluxed to the second separation tower, and triethylene glycol is produced from the other line.

[0009] Preferably, the first separation tower includes a first separation main tower and a first separation sub-tower, the bottom of the low-pressure tower is connected to the first separation sub-tower, the top of the first separation sub-tower is connected to the upper part of the first separation main tower, and the bottom of the first separation sub-tower is connected to the lower part of the first separation main tower. Part of the gaseous material in the first separation main tower can be transported to the upper part of the first separation sub-tower for reflux, and part of the liquid material in the first separation main tower can be transported to the lower part of the first separation sub-tower for reflux.

[0010] Preferably, the steam vaporizer further comprises a first flash tank and a second flash tank, the second reboiler being connected to the first flash tank, the condensate after the overhead steam of the high-pressure tower is heat exchanged and cooled in the second reboiler enters the first flash tank, the third reboiler being connected to the first flash tank, the condensate after the overhead steam of the medium-pressure tower is heat exchanged and cooled in the third reboiler enters the first flash tank, the top of the first flash tank is connected to the top of the second flash tank, the saturated steam extracted from the top of the first flash tank is decompressed by a pressure reducing valve and transported to the top of the second flash tank, the bottom of the first flash tank is connected to the second flash tank, the high-temperature water extracted from the bottom of the first flash tank is cooled by a condenser and transported to the middle of the second flash tank, the fourth reboiler is connected to the middle of the second flash tank, the condensate after the overhead steam of the first separation tower is heat exchanged and cooled in the fourth reboiler enters the second flash tank, the top of the second flash tank extracts saturated steam, and the bottom of the second flash tank extracts high-temperature water.

[0011] Preferably, the condensate after the heating steam is cooled by heat exchange in the first reboiler is discharged through a heating steam discharge line, and the condensate after the heating steam is cooled by heat exchange in the fifth reboiler is discharged through a heating steam discharge line.

[0012] Preferably, the distillation system removes water from the ethylene glycol mixture to less than 20%.

[0013] Preferably, the operating pressure of the high-pressure tower is 1000-1200 kPa, the operating pressure of the medium-pressure tower is 900-1100 kPa, and the operating pressure range of the low-pressure tower is 400-600 kPa.

[0014] The present invention also provides a separation method of the energy-saving device for separating ethylene glycol mixtures, comprising the following steps:

[0015] Step 1: The ethylene glycol mixture is transported to the high-pressure tower, and the first reboiler using external heating steam as a heat source heats the ethylene glycol mixture. A portion of the primary concentrate extracted from the bottom of the high-pressure tower is refluxed to the high-pressure tower through the first reboiler, and the remaining portion is transported to the medium-pressure tower for further distillation.

[0016] Step 2: The overhead steam of the high-pressure tower is used as a heat source for the second reboiler to heat the primary concentrated liquid. The secondary concentrated liquid extracted from the bottom of the medium-pressure tower is partially refluxed to the medium-pressure tower through the second reboiler, and the remaining portion is transported to the low-pressure tower for further distillation.

[0017] Step 3: The overhead steam of the medium-pressure tower is used as a heat source for the third reboiler to heat the secondary concentrated liquid. The tertiary concentrated liquid extracted from the bottom of the low-pressure tower is partially refluxed to the low-pressure tower through the third reboiler, and the remaining portion is transported to the first separation tower for material separation.

[0018] Step 4: The overhead steam of the low-pressure tower is used as a heat source for the fourth reboiler to heat the tertiary concentrate. Water is produced from the overhead of the first separation tower. After cooling in a condenser, a portion of the water is refluxed to the upper portion of the first separation tower, and the remaining portion is transported to the outside. Ethylene glycol is produced from the side line of the first separation tower, and a mixture of diethylene glycol and triethylene glycol is produced from the bottom of the first separation tower. A portion of the mixture of diethylene glycol and triethylene glycol is refluxed to the first separation tower through the fourth reboiler, and the remaining portion is transported to the second separation tower for further material separation.

[0019] Step 5: The fifth reboiler using external heating steam as a heat source heats the mixture of diethylene glycol and triethylene glycol, diethylene glycol is extracted from the top of the second separation tower, and after cooling through a condenser, a portion of the diethylene glycol is refluxed to the upper part of the first separation tower, and the other portion is transported to the outside, and triethylene glycol is extracted from the bottom of the first separation tower, a portion of the triethylene glycol is refluxed to the second separation tower through the fifth reboiler, and the other portion is transported to the outside.

[0020] Preferably, the concentration of the ethylene glycol extracted in step 4 is 99.9%.

[0021] Preferably, the concentration of the diethylene glycol produced in step 5 is 99.9%, and the concentration of the triethylene glycol produced is 99.9%.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] The present invention provides an energy-saving device and method for separating an ethylene glycol mixture. The overhead steam of a high-pressure tower of a distillation system serves as a heat source for a second reboiler at the bottom of a medium-pressure tower, and the overhead steam of the medium-pressure tower serves as a heat source for a third reboiler at the bottom of a low-pressure tower. The distillation system can remove more than 80% of water from the ethylene glycol mixture through a triple-effect distillation process. The distillation system fully utilizes the latent heat of the overhead steam, reduces the external heat source required for the reboiler, saves steam consumption, and has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of an energy-saving device for separating ethylene glycol mixtures.

[0026] In the figure: T1-high-pressure tower; T2-medium-pressure tower; T3-low-pressure tower; T41-first separation sub-tower; T42-first separation main tower; T5-second separation tower; F1-first flash tank; F2-second flash tank; E1-condenser; V1-pressure reducing valve; R1-first reboiler; R2-second reboiler; R3-third reboiler; R4-fourth reboiler; R5-fifth reboiler; 1-23 represent the serial numbers of the material flow pipelines, and the arrows represent the direction of material flow. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The purpose of the present invention is to provide an energy-saving device and separation method for separating ethylene glycol mixtures to solve the problems existing in the above-mentioned prior art, which can save the consumption of heating steam, have low overall energy consumption and simple process.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] This embodiment provides an energy-saving device for separating an ethylene glycol mixture, comprising a distillation system and a mixed alcohol separation system;

[0032] The distillation system includes a high-pressure tower T1, a medium-pressure tower T2, a low-pressure tower T3, a first reboiler R1, a second reboiler R2 and a third reboiler R3. The high-pressure tower T1 is connected to the ethylene glycol mixture feed line, and the first reboiler R1 is connected to the heating steam feed line. The heating steam enters the first reboiler R1 as the heat source of the first reboiler R1. The tower bottom outlet pipeline of the high-pressure tower T1 is divided into two. The material of one line is reboiled in the first reboiler R1 and then refluxed to the high-pressure tower T1. The other line is connected to the medium-pressure tower T2. The top of the high-pressure tower T1 is connected to the second reboiler R2. The tower of the high-pressure tower T1 The top steam enters the second reboiler R2 as the heat source of the second reboiler R2, and the tower bottom outlet pipeline of the medium-pressure tower T2 is divided into two. The material of one line is reboiled in the second reboiler R2 and then refluxed to the medium-pressure tower T2, and the other line is connected to the low-pressure tower T3. The top of the medium-pressure tower T2 is connected to the third reboiler R3. The top steam of the medium-pressure tower T2 enters the third reboiler R3 as the heat source of the third reboiler R3. The tower bottom outlet pipeline of the low-pressure tower T3 is divided into two. The material of one line is reboiled in the third reboiler R3 and then refluxed to the low-pressure tower T3, and the other line is connected to the mixed alcohol separation system;

[0033] The mixed alcohol separation system includes a first separation tower, a second separation tower T5, a fourth reboiler R4 and a fifth reboiler R5. The bottom of the low-pressure tower T3 is connected to the first separation tower, and the top of the low-pressure tower T3 is connected to the fourth reboiler R4. The top steam of the low-pressure tower T3 enters the fourth reboiler R4 as a heat source for the fourth reboiler R4. Water is produced from the top of the first separation tower, and ethylene glycol product is produced from the side line of the first separation tower. The bottom outlet pipeline of the first separation tower is divided into two, and the material of one line is refluxed after being reboiled in the fourth reboiler R4. To the first separation tower, another line is connected to the second separation tower T5, the fifth reboiler R5 is connected to and communicated with the lower part of the second separation tower T5, the fifth reboiler R5 is connected to the heating steam feed line, and the heating steam enters the fifth reboiler R5 as the heat source of the fifth reboiler R5, and the diethylene glycol product is produced from the top of the second separation tower T5. The bottom outlet pipeline of the second separation tower T5 is divided into two. The material of one line is reboiled in the fifth reboiler R5 and then refluxed to the second separation tower T5, and the other route produces triethylene glycol product.

[0034] The overhead steam of the high-pressure tower T1 of the distillation system is used as the heat source for the second reboiler R2 at the bottom of the medium-pressure tower T2, and the overhead steam of the medium-pressure tower T2 is used as the heat source for the third reboiler R3 at the bottom of the low-pressure tower T3. The distillation system can remove more than 80% of the water in the ethylene glycol mixture through a three-effect distillation process, reduce the water content in the mixture entering the mixed alcohol separation system, and separate multiple components through the first separation tower and the second separation tower T5, thereby achieving deep energy saving of the device; the distillation system fully utilizes the latent heat of the overhead steam, reduces the external heat source required for the reboiler, can save more than 30% of steam consumption, and has significant economic benefits.

[0035] In the embodiment of this embodiment, it is further preferred that the first separation tower includes a first separation main tower T42 and a first separation sub-tower T41, the bottom of the low-pressure tower T3 is connected to the first separation sub-tower T41, the top of the first separation sub-tower T41 is connected to the upper part of the first separation main tower T42, and the bottom of the first separation sub-tower T41 is connected to the lower part of the first separation main tower T42. Part of the gaseous material in the first separation main tower T42 can be transported to the upper part of the first separation sub-tower T41 for reflux, and part of the liquid material in the first separation main tower T42 can be transported to the lower part of the first separation sub-tower T41 for reflux. The first separation sub-tower T41 can pre-separate the materials after triple-effect distillation to initially separate water and an ethylene glycol / diethylene glycol / triethylene glycol mixture. Since the degree of back-mixing within the tower is reduced, the thermodynamic efficiency of the separation process is improved, thereby improving energy efficiency. In addition, the sub-tower utilizes the internal flow for heat exchange without a condenser or reboiler, thereby reducing equipment investment.

[0036] In the embodiment of this embodiment, it is further preferred that the energy-saving device for separating the ethylene glycol mixture further includes a first flash tank F1 and a second flash tank F2, the second reboiler R2 is connected to the first flash tank F1, the top steam of the high-pressure tower T1 is heat exchanged in the second reboiler R2 and the condensate after cooling enters the first flash tank F1, the third reboiler R3 is connected to the first flash tank F1, the top steam of the medium-pressure tower T2 is heat exchanged in the third reboiler R3 and the condensate after cooling enters the first flash tank F1, and saturated steam and high-temperature water are obtained after flash evaporation in the first flash tank F1. 2, the saturated steam produced from the top of the first flash tank F1 is reduced in pressure by the pressure reducing valve V1 and then transported to the top of the second flash tank F2, the bottom of the first flash tank F1 is connected to the second flash tank F2, the high-temperature water produced from the bottom of the first flash tank F1 is cooled by the condenser E1 and then transported to the middle of the second flash tank F2, the fourth reboiler R4 is connected to the middle of the second flash tank F2, the top steam of the first separation tower is condensed after heat exchange and cooling in the fourth reboiler R4, and enters the second flash tank F2, low-pressure saturated steam is produced from the top of the second flash tank F2, and high-temperature water is produced from the bottom of the second flash tank F2.

[0037] It is further preferred in the implementation of this embodiment that the condensate after the heating steam is heat exchanged and cooled in the first reboiler R1 is discharged through the heating steam discharge line, and the condensate after the heating steam is heat exchanged and cooled in the fifth reboiler R5 is discharged through the heating steam discharge line.

[0038] It is further preferred in the implementation of this embodiment that the distillation system removes water from the ethylene glycol mixture to less than 20%.

[0039] It is further preferred in the embodiment of this embodiment that the operating pressure of the high-pressure tower T1 is 1000-1200 kPa, the operating pressure of the medium-pressure tower T2 is 900-1100 kPa, and the operating pressure range of the low-pressure tower T3 is 400-600 kPa.

[0040] Example 2

[0041] This embodiment provides a separation method for the energy-saving device for separating an ethylene glycol mixture according to embodiment 1, comprising the following steps:

[0042] Step 1: The ethylene glycol mixture is transferred to the high-pressure tower T1. The first reboiler R1 uses external heating steam as a heat source to heat the ethylene glycol mixture. A portion of the primary concentrate extracted from the bottom of the high-pressure tower T1 is refluxed to the high-pressure tower T1 through the first reboiler R1, and the remaining portion is transferred to the medium-pressure tower T2 for further distillation.

[0043] Step 2: The overhead steam from the high-pressure tower T1 is used as the heat source for the second reboiler R2 to heat the primary concentrate. The secondary concentrate extracted from the bottom of the medium-pressure tower T2 is partially refluxed to the medium-pressure tower T2 through the second reboiler R2, and the remaining portion is transferred to the low-pressure tower T3 for further distillation.

[0044] Step 3: The overhead steam from the medium-pressure tower T2 is used as the heat source for the third reboiler R3 to heat the secondary concentrate. The tertiary concentrate extracted from the bottom of the low-pressure tower T3 is partially refluxed to the low-pressure tower T3 through the third reboiler R3, and the remaining portion is transported to the first separation tower for material separation.

[0045] Step 4: The overhead steam from the low-pressure tower T3 is used as a heat source in the fourth reboiler R4 to heat the tertiary concentrate. Water is produced from the overhead of the first separation tower. After cooling in the condenser E1, a portion of the water is refluxed to the upper portion of the first separation tower, and the remaining portion is transported to the outside. Ethylene glycol product is produced from the side line of the first separation tower, and a mixture of diethylene glycol and triethylene glycol is produced from the bottom of the first separation tower. A portion of the mixture of diethylene glycol and triethylene glycol is refluxed to the first separation tower through the fourth reboiler R4, and the remaining portion is transported to the second separation tower T5 for further material separation.

[0046] Step 5: The mixture of diethylene glycol and triethylene glycol is heated in the fifth reboiler R5 using external heating steam as a heat source. The diethylene glycol product is extracted from the top of the second separation tower T5. After cooling in the condenser E1, a portion of the diethylene glycol product is refluxed to the upper part of the first separation tower, and the other portion is transported to the outside. The triethylene glycol product is extracted from the bottom of the first separation tower. A portion of the triethylene glycol product is refluxed to the second separation tower T5 through the fifth reboiler R5, and the other portion is transported to the outside.

[0047] In the embodiment of this embodiment, it is further preferred that the concentration of the ethylene glycol product extracted in step 4 is 99.9%, the concentration of the diethylene glycol product extracted in step 5 is 99.9%, and the concentration of the triethylene glycol product extracted is 99.9%. The separated ethylene glycol product, diethylene glycol product, and triethylene glycol product have high purity.

[0048] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An energy-saving device for separating an ethylene glycol mixture, characterized in that: Including distillation system and mixed alcohol separation system; The distillation system includes a high-pressure tower, a medium-pressure tower, a low-pressure tower, a first reboiler, a second reboiler and a third reboiler. The high-pressure tower is connected to the ethylene glycol mixture feed line, the first reboiler is connected to the heating steam feed line, and the heating steam enters the first reboiler as the heat source of the first reboiler. The tower bottom outlet pipeline of the high-pressure tower is divided into two. The material of one line is reboiled in the first reboiler and then refluxed to the high-pressure tower, and the other line is connected to the medium-pressure tower. The top of the high-pressure tower is connected to the second reboiler, and the top steam of the high-pressure tower is used as the heat source. The heat source of the second reboiler enters the second reboiler, the tower bottom outlet pipeline of the medium-pressure tower is divided into two, the material of one line is reboiled in the second reboiler and then refluxed to the medium-pressure tower, and the other line is connected to the low-pressure tower, the top of the medium-pressure tower is connected to the third reboiler, and the overhead steam of the medium-pressure tower enters the third reboiler as the heat source of the third reboiler, the tower bottom outlet pipeline of the low-pressure tower is divided into two, the material of one line is reboiled in the third reboiler and then refluxed to the low-pressure tower, and the other line is connected to the mixed alcohol separation system; The mixed alcohol separation system includes a first separation tower, a second separation tower, a fourth reboiler, and a fifth reboiler. The bottom of the low-pressure tower is connected to the first separation tower, and the top of the low-pressure tower is connected to the fourth reboiler. The overhead steam of the low-pressure tower enters the fourth reboiler as a heat source for the fourth reboiler. Water is produced from the top of the first separation tower, and ethylene glycol is produced from the side line of the first separation tower. The bottom outlet pipeline of the first separation tower is divided into two, and the material of one line is reboiled in the fourth reboiler and then refluxed to the first separation tower, and the other line is connected to the second separation tower. The fifth reboiler is connected and connected to the lower part of the second separation tower. The fifth reboiler is connected to a heating steam feed line, and the heating steam enters the fifth reboiler as a heat source for the fifth reboiler. Diethylene glycol is produced from the top of the second separation tower. The bottom outlet pipeline of the second separation tower is divided into two, and the material of one line is reboiled in the fifth reboiler and then refluxed to the second separation tower, and triethylene glycol is produced from the other line. The first separation tower includes a first separation main tower and a first separation sub-tower, the bottom of the low-pressure tower is connected to the first separation sub-tower, the top of the first separation sub-tower is connected to the upper part of the first separation main tower, and the bottom of the first separation sub-tower is connected to the lower part of the first separation main tower. Part of the gaseous material in the first separation main tower can be transported to the upper part of the first separation sub-tower for reflux, and part of the liquid material in the first separation main tower can be transported to the lower part of the first separation sub-tower for reflux; The steam turbine further comprises a first flash tank and a second flash tank, wherein the second reboiler is in communication with the first flash tank, and the condensate after the overhead steam of the high-pressure tower is cooled by heat exchange in the second reboiler enters the first flash tank. The third reboiler is in communication with the first flash tank, and the condensate after the overhead steam of the intermediate-pressure tower is cooled by heat exchange in the third reboiler enters the first flash tank. The top of the first flash tank is in communication with the top of the second flash tank, and the saturated steam extracted from the top of the first flash tank is reduced in pressure by a pressure reducing valve and transported to the top of the second flash tank. The bottom of the first flash tank is in communication with the second flash tank, and the high-temperature water extracted from the bottom of the first flash tank is cooled by a condenser and transported to the middle of the second flash tank. The fourth reboiler is in communication with the middle of the second flash tank, and the condensate after the overhead steam of the first separation tower is cooled by heat exchange in the fourth reboiler enters the second flash tank. The top of the second flash tank extracts saturated steam, and the bottom of the second flash tank extracts high-temperature water.

2. The energy-saving device for separating ethylene glycol mixture according to claim 1, characterized in that: The condensate after the heating steam is cooled by heat exchange in the first reboiler is discharged through the heating steam discharge line, and the condensate after the heating steam is cooled by heat exchange in the fifth reboiler is discharged through the heating steam discharge line.

3. The energy-saving device for separating ethylene glycol mixture according to claim 1, characterized in that: The distillation system removes water from the glycol mixture to less than 20%.

4. The energy-saving device for separating ethylene glycol mixture according to claim 1, characterized in that: The operating pressure of the high-pressure tower is 1000-1200 kPa, the operating pressure of the medium-pressure tower is 900-1100 kPa, and the operating pressure range of the low-pressure tower is 400-600 kPa.

5. A separation method for an energy-saving device for separating an ethylene glycol mixture according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: The ethylene glycol mixture is transported to the high-pressure tower, and the first reboiler using external heating steam as a heat source heats the ethylene glycol mixture. A portion of the primary concentrate extracted from the bottom of the high-pressure tower is refluxed to the high-pressure tower through the first reboiler, and the remaining portion is transported to the medium-pressure tower for further distillation. Step 2: The overhead steam of the high-pressure tower is used as a heat source for the second reboiler to heat the primary concentrated liquid. The secondary concentrated liquid extracted from the bottom of the medium-pressure tower is partially refluxed to the medium-pressure tower through the second reboiler, and the remaining portion is transported to the low-pressure tower for further distillation. Step 3: The overhead steam of the medium-pressure tower is used as a heat source for the third reboiler to heat the secondary concentrated liquid. The tertiary concentrated liquid extracted from the bottom of the low-pressure tower is partially refluxed to the low-pressure tower through the third reboiler, and the remaining portion is transported to the first separation tower for material separation. Step 4: The overhead steam of the low-pressure tower is used as a heat source for the fourth reboiler to heat the tertiary concentrate. Water is produced from the overhead of the first separation tower. After cooling in a condenser, a portion of the water is refluxed to the upper portion of the first separation tower, and the remaining portion is transported to the outside. Ethylene glycol is produced from the side line of the first separation tower, and a mixture of diethylene glycol and triethylene glycol is produced from the bottom of the first separation tower. A portion of the mixture of diethylene glycol and triethylene glycol is refluxed to the first separation tower through the fourth reboiler, and the remaining portion is transported to the second separation tower for further material separation. Step 5: The fifth reboiler using external heating steam as a heat source heats the mixture of diethylene glycol and triethylene glycol, diethylene glycol is extracted from the top of the second separation tower, and after cooling through a condenser, a portion of the diethylene glycol is refluxed to the upper part of the first separation tower, and the other portion is transported to the outside, and triethylene glycol is extracted from the bottom of the first separation tower, a portion of the triethylene glycol is refluxed to the second separation tower through the fifth reboiler, and the other portion is transported to the outside.

6. The separation method of the energy-saving device for separating ethylene glycol mixture according to claim 5, characterized in that: The concentration of ethylene glycol extracted in step 4 is 99.9%.

7. The separation method of the energy-saving device for separating ethylene glycol mixture according to claim 5, characterized in that: The concentration of the diethylene glycol produced in step 5 is 99.9%, and the concentration of the triethylene glycol produced is 99.9%.

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