System for reducing content of butanediol in ethylene glycol rectifying tower

Abstract

The invention provides a system for reducing the content of butanediol in an ethylene glycol rectifying tower, and relates to the technical field of alcohol separation, the system comprises a rectifying tower and a feeding mechanism, the feeding mechanism comprises a steam pipeline and a desalted water pipeline, the steam pipeline is arranged at the spray guide position of the desalted water pipeline through piping, and the desalted water pipeline is arranged in the rectifying tower. And the steam pipeline and the desalted water pipeline are both connected with a feeding hole of a tower kettle of the rectifying tower. According to the invention, the steam pipeline is additionally arranged at the spray guide position of the desalted water pipeline, after steam enters the tower kettle, butanediol is pushed to rise to the tower top, and more butanediol is conveyed to the reflux tank at the tower top, so that the content of butanediol in the tower is reduced; the process is simple to operate, the separation cost is reduced, and the purification purity of ethylene glycol is improved.

Description

Technical Field

[0001] The invention relates to the technical field of alcohol separation, and in particular to a system for reducing the content of butanediol in an ethylene glycol distillation tower. Background Art

[0002] As an important chemical raw material, ethylene glycol is mainly used in the production of polyester, terylene, polyester resin, plasticizer, surfactant, synthetic fiber, cosmetics, etc. It can also be used as a solvent for dyes and inks, coolant, or to prepare engine antifreeze, gas dehydrating agent, resin manufacturing, and wetting agent for cellophane, fiber, leather, and adhesives. Due to the multiple uses of ethylene glycol, my country has become the world's largest consumer of ethylene glycol. In order to reduce dependence on petroleum resources, the coal-to-ethylene glycol route has received more and more attention, which is of great practical significance to my country.

[0003] A distillation tower is a tower-type gas-liquid contact device for distillation. By utilizing the different volatilities of the components in the mixture, that is, the different vapor pressures of the components at the same temperature, the light components (low-boiling substances) in the liquid phase are transferred to the gas phase, and the heavy components (high-boiling substances) in the gas phase are transferred to the liquid phase, thereby achieving the purpose of separation. However, in the dimethyl oxalate process route of coal-to-ethylene glycol, the boiling points of ethylene glycol and the by-product 1,2-butanediol are relatively close, with a difference of only 1°C, and the two will form a low-point azeotrope, resulting in a high content of butanediol in the tower, that is, the difficulty of separating the two is high, which ultimately leads to a reduction in the purity of the ethylene glycol product.

[0004] Based on the limitations of the prior art, the present invention discloses a system for reducing the content of butanediol in an ethylene glycol distillation tower, which has simple process operation, reduced separation cost and high ethylene glycol purification purity. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the deficiencies in the prior art, the present invention provides a system for reducing the butanediol content in an ethylene glycol distillation tower, which solves the problems of high butanediol content in the existing distillation tower and great difficulty in separating butanediol from ethylene glycol.

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] The system for reducing the content of butanediol in an ethylene glycol distillation tower comprises a distillation tower and a feeding mechanism, wherein the feeding mechanism comprises a steam pipeline and a desalted water pipeline, wherein the steam pipeline is arranged at the drainage point of the desalted water pipeline, and the steam pipeline and the desalted water pipeline are both connected to the feed port of the distillation tower kettle.

[0010] Preferably, the temperature of the steam in the steam pipeline entering the tower kettle is 150° C., the pressure is 0.5 MPa, and the flow rate is 0.2 t / h.

[0011] Preferably, the temperature of the desalted water in the desalted water pipeline entering the tower kettle is 150° C., the pressure is 0.7 MPa, and the flow rate is 0.2 t / h.

[0012] Preferably, the feeding mechanism further comprises a nitrogen pipeline, which is arranged separately from the desalted water pipeline and is connected to the feed port of the distillation tower kettle.

[0013] Preferably, the pressure of nitrogen introduced into the nitrogen pipeline is 0.45 MPa.

[0014] Preferably, it also includes a crude ethylene glycol inlet pipeline connected to the distillation tower, a bottom reboiler connected to the distillation tower, a top gas phase pipe connected to the top of the distillation tower at one end, a top condenser connected to the other end of the top gas phase pipe, a top reflux tank connected to the top condenser, and a top reflux pipe for returning the liquid in the top reflux tank to the top of the distillation tower.

[0015] Preferably, the bottom temperature of the distillation tower is maintained at 155°C.

[0016] (III) Beneficial effects

[0017] The present invention provides a system for reducing the content of butanediol in an ethylene glycol distillation tower. Compared with the prior art, the system has the following beneficial effects:

[0018] The system for reducing the butanediol content in an ethylene glycol distillation tower disclosed by the invention is provided with a desalted water pipeline and a steam pipeline, the desalted water pipeline and the steam pipeline are not used at the same time, and steam or desalted water is introduced into the tower kettle respectively.

[0019] The present invention has two improvements. First, a steam pipeline is added to the desalted water pipeline. After the steam enters the tower kettle, it pushes the butanediol to the top of the tower. More butanediol is transmitted to the top reflux tank, thereby reducing the butanediol content in the tower. Second, the desalted water pipeline of the prior art is usually used for maintenance rather than distillation. During distillation, the desalted water is sent to the tower kettle, and the desalted water is instantly vaporized. The gas pushes the butanediol to the top of the tower and then refluxes, thereby reducing the butanediol content in the tower. The process of the present invention is simple to operate, the separation cost is reduced, and the purity of ethylene glycol purification is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0021] Figure 1 It is a process flow chart of an embodiment of the present invention.

[0022] Among them, 1. distillation tower; 2. feeding mechanism; 21. steam pipeline; 22. desalted water pipeline; 23. nitrogen pipeline; 3. crude ethylene glycol inlet pipeline; 4. tower bottom reboiler; 5. tower top gas phase pipe; 6. tower top condenser; 7. tower top reflux tank; 8. tower top reflux pipe. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0024] The embodiment of the present application provides a system for reducing the butanediol content in an ethylene glycol distillation tower, thereby solving the problems of high butanediol content in the existing distillation tower and great difficulty in separating butanediol from ethylene glycol. The purity of ethylene glycol purified by using the system is improved.

[0025] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0026] Example:

[0027] like Figure 1 As shown, the system for reducing the butanediol content in the ethylene glycol distillation tower 1 includes the distillation tower 1, a feeding mechanism 2, a crude ethylene glycol inlet pipeline 3, a tower bottom reboiler 4, a tower top gas phase pipe 5, a tower top condenser 6, a tower top reflux tank 7 and a tower top reflux pipe 8.

[0028] The feed mechanism 2 comprises a steam pipeline 21 , a desalted water pipeline 22 and a nitrogen pipeline 23 , and the steam pipeline 21 , the desalted water pipeline 22 and the nitrogen pipeline 23 are all connected to the feed port of the reactor of the distillation tower 1 .

[0029] The steam pipeline 21 is arranged at the drainage point of the desalted water pipeline 22, and is used to introduce steam during distillation in the tower.

[0030] The temperature of the steam entering the tower kettle in the steam pipeline 21 is 150°C, the pressure is 0.5MPa, the flow rate is 0.2t / h, and the temperature of the tower kettle of the distillation tower 1 is maintained at 155°C.

[0031] The desalted water pipeline 22 has two uses, one is to reduce the content of butanediol in the tower during distillation, and the other is to inspect whether the tower is operating normally. When used to reduce the content of butanediol in the tower during distillation, the temperature of the desalted water entering the tower kettle is 150°C, the pressure is 0.7MPa, and the flow rate is 0.2t / h.

[0032] The nitrogen pipeline 23 is set separately from the desalted water pipeline 22 and is used to inspect whether the tower is operating normally. The nitrogen pressure introduced into the nitrogen pipeline 23 is 0.45 MPa.

[0033] The crude ethylene glycol inlet pipeline 3 is separately provided for introducing a mixture of ethylene glycol and butanediol.

[0034] The tower bottom reboiler 4 is connected to the distillation tower 1 and is used to provide heat for the distillation tower 1 .

[0035] One end of the tower top gas phase pipe 5 is connected to the tower top of the distillation tower 1, and the other end is connected to the tower top condenser 6, and the mixture of butanediol and ethylene glycol at the tower top is sent to the condenser for condensation.

[0036] The top reflux tank 7 is connected to the top condenser 6, and the condensed butanediol and ethylene glycol mixture is sent to the top reflux tank 7. The butanediol content in the top reflux tank 7 increases, and the ethylene glycol content will decrease, thereby achieving the effect of increasing the amount of ethylene glycol purification.

[0037] The liquid in the tower top reflux tank 7 is transferred back to the tower top through the tower top reflux pipe 8.

[0038] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0039] The system for reducing the butanediol content in an ethylene glycol distillation tower disclosed by the invention is provided with a desalted water pipeline and a steam pipeline, the desalted water pipeline and the steam pipeline are not used at the same time, and steam or desalted water is introduced into the tower kettle respectively.

[0040] The present invention has two improvements. First, a steam pipeline is added to the desalted water pipeline. After the steam enters the tower kettle, it pushes the butanediol to the top of the tower. More butanediol is transmitted to the top reflux tank, thereby reducing the butanediol content in the tower. Second, the desalted water pipeline of the prior art is usually used for maintenance rather than distillation. During distillation, the desalted water is sent to the tower kettle, and the desalted water is instantly vaporized. The gas pushes the butanediol to the top of the tower and then refluxes, thereby reducing the butanediol content in the tower. The process of the present invention is simple to operate, the separation cost is reduced, and the purity of ethylene glycol purification is improved.

[0041] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for reducing the content of butanediol in an ethylene glycol distillation tower, characterized in that: The invention comprises a distillation tower (1) and a feeding mechanism (2), wherein the feeding mechanism (2) comprises a steam pipeline (21) and a desalted water pipeline (22), wherein the steam pipeline (21) is arranged at the drainage point of the desalted water pipeline (22), and the steam pipeline (21) and the desalted water pipeline (22) are both connected to the feeding port of the bottom of the distillation tower (1).

2. The system for reducing the content of butanediol in an ethylene glycol distillation tower according to claim 1, characterized in that: The temperature of the steam in the steam pipeline (21) entering the tower kettle is 150°C, the pressure is 0.5 MPa, and the flow rate is 0.2 t / h.

3. The system for reducing the content of butanediol in an ethylene glycol distillation tower according to claim 1, characterized in that: The temperature of the desalted water in the desalted water pipeline (22) entering the tower kettle is 150°C, the pressure is 0.7 MPa, and the flow rate is 0.2 t / h.

4. The system for reducing the content of butanediol in an ethylene glycol distillation tower according to claim 1, characterized in that: The feed mechanism (2) further comprises a nitrogen pipeline (23), which is arranged separately from the desalted water pipeline (22) and is connected to a feed port of the bottom of the distillation tower (1).

5. The system for reducing the content of butanediol in an ethylene glycol distillation tower according to claim 4, characterized in that: The pressure of nitrogen introduced into the nitrogen pipeline (23) is 0.45 MPa.

6. The system for reducing the content of butanediol in an ethylene glycol distillation tower according to claim 1, characterized in that: The invention also comprises a crude ethylene glycol inlet pipeline (3) connected to the distillation tower (1), a tower bottom reboiler (4) connected to the distillation tower (1), a tower top gas phase pipe (5) connected to the top of the distillation tower (1) at one end, a tower top condenser (6) connected to the other end of the tower top gas phase pipe (5), a tower top reflux tank (7) connected to the tower top condenser (6), and a tower top reflux pipe (8) for returning the liquid in the tower top reflux tank (7) to the top of the distillation tower (1).

7. The system for reducing the content of butanediol in an ethylene glycol distillation tower according to claim 1, characterized in that: The bottom temperature of the distillation tower (1) is maintained at 155°C.

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