Device for separating methanol-ethanol-water through double-tower rectification

Abstract

The utility model relates to the technical field of rectification and purification, in particular to a device for separating methanol-ethanol-water through double-tower rectification, which comprises a methanol rectification tower and an ethanol rectification tower, and a feed port of the methanol rectification tower is connected with a methanol-ethanol-water ternary mixed solution raw material supply system through a pipeline. The bottom of the methanol rectifying tower is connected with a feed inlet of the ethanol rectifying tower through a pipeline, the top of the methanol rectifying tower is connected with a methanol recovery device through a pipeline, and the bottom of the ethanol rectifying tower is connected with a water recovery device through a pipeline. According to the utility model, heat in the rectification process can be effectively utilized, energy is saved, and the tower raffinate is water and environment-friendly. Meanwhile, the equipment is simple, high in energy efficiency, easy to adjust and flexible to operate, and the COD content in the wastewater can be effectively reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of distillation and purification, in particular to a device for separating methanol-ethanol-water by double-tower distillation. Background Art

[0002] Methanol is an important basic chemical raw material, which is widely used in the chemical, pharmaceutical, papermaking and other industries; ethanol is a widely used organic chemical, which is widely used in the fields of food, beverages, medicines, coatings and cosmetics. Aqueous solutions of methanol and ethanol are often formed in the production process of the chemical and pharmaceutical industries. In the existing technology, methanol or ethanol is generally recovered by distillation.

[0003] The traditional methanol and ethanol aqueous solution distillation system has the following technical defects:

[0004] (1) A large amount of heat is consumed. In traditional distillation operations, the heat is not fully recovered and utilized during the distillation process, the residual temperature of the material is not reasonably utilized, the heat transfer equipment is inefficient, resulting in large heat losses, low steam utilization, part of the steam cannot be fully utilized, and the process control is unclear.

[0005] (2) For aqueous solutions containing methanol and ethanol, if they are discharged directly or only methanol or ethanol is distilled, the discharge of the tower residual liquid will cause environmental pollution and waste of resources. Therefore, there is a great prospect for recycling and reusing them.

[0006] (3) Single-tower distillation is adopted. The single-tower distillation process is to select one distillation tower to complete the distillation process; the raw materials are fed into the distillation tower from the top, and after the distillation process, the light fraction is extracted from the top of the tower, the high-boiling point heavy fraction and water are extracted from the bottom of the tower, and methanol is drawn out from the second tower plate below the top of the distillation tower; the single-tower distillation process has the characteristics of low investment and low cost, which can reduce energy loss, but the distillation efficiency is not high and the final product quality is not high; the single-tower distillation can only perform simple separation and purification of methanol, and the product accuracy cannot meet industrial requirements; the distillation temperature of methanol and ethanol needs to be adjusted, and it is difficult to control parameters such as temperature and pressure. The by-products are not fully utilized, resulting in waste of resources and low recovery purity. Utility Model Content

[0007] Aiming at the problems of waste of distillation heat, environmental pollution of tower residual liquid and difficult process control in the prior art, the utility model provides a double-tower distillation device for separating methanol-ethanol-water, which can effectively utilize the heat in the distillation process, save energy, and the tower residual liquid is water-friendly and environmentally friendly. At the same time, the equipment is simple, energy-efficient, easy to adjust, and flexible to operate, which can effectively reduce the COD content in wastewater.

[0008] The utility model provides a double-tower distillation separation device for methanol-ethanol-water, comprising a methanol distillation tower and an ethanol distillation tower, wherein a feed port of the methanol distillation tower is connected to a methanol-ethanol-water ternary mixed solution raw material supply system through a pipeline, a bottom of the methanol distillation tower is connected to a feed port of the ethanol distillation tower through a pipeline, a top of the methanol distillation tower is connected to a methanol recovery device through a pipeline, and a bottom of the ethanol distillation tower is connected to a water recovery device through a pipeline.

[0009] Furthermore, the methanol recovery device includes a first top condenser, a first reflux tank, a first reflux pump, and a first top extraction condenser; the top outlet of the methanol distillation tower is connected to the inlet end of the first top condenser, the outlet end of the first top condenser is connected to the inlet end of the first reflux tank, the outlet end of the first reflux tank is connected to the inlet end of the first reflux pump, and the outlet end of the first reflux pump is divided into two paths, which are respectively connected to the top of the methanol distillation tower and the inlet end of the first top extraction condenser, and the outlet end of the first top extraction condenser is used to produce products. The methanol recovery device separates and purifies the mixed solution through distillation according to the different volatilities of the components, distills out the light component methanol in the mixed solution, obtains high-purity methanol, and achieves the purpose of recovering methanol.

[0010] Furthermore, the ethanol recovery device includes a second top condenser, a second reflux tank, a second reflux pump, and a second top extraction condenser; the inlet end of the second top condenser is connected to the top outlet of the ethanol distillation tower, the outlet end of the second top condenser is connected to the inlet end of the second reflux tank, the outlet end of the second reflux tank is connected to the inlet end of the second reflux pump, the outlet end of the second reflux pump is divided into two paths, which are respectively connected to the top of the ethanol distillation tower and the inlet end of the second top extraction condenser, and the outlet end of the second top extraction condenser is used to output products; utilizing the principle that the boiling point of ethanol is lower than that of water and other solutions, the ethanol solution to be recovered is heated and volatilized, and after distillation in the tower body, high-purity ethanol is precipitated, thereby increasing the concentration of ethanol recovery and achieving the purpose of recovering ethanol.

[0011] Furthermore, a first preheater is provided on the pipeline connecting the feed inlet of the methanol distillation tower with the methanol-ethanol-water ternary mixed solution raw material supply system for preheating the methanol-ethanol-water ternary mixed solution.

[0012] Furthermore, a first reboiler is provided at the bottom of the methanol distillation tower for reboiling circulation at the bottom of the tower; the first reboiler can adjust the bottom temperature of the methanol distillation tower, rationally utilize the residual temperature in the distillation process to obtain higher purity methanol, and overcome the shortcomings of traditional distillation operations such as insufficient heat recovery and utilization in the distillation process and large heat loss.

[0013] Furthermore, a first bottom extraction pump and a second preheater are provided on the pipeline connecting the bottom of the methanol distillation tower and the feed port of the ethanol distillation tower; the first bottom extraction pump delivers a mixed solution of water and ethanol to the ethanol distillation tower to extract light component ethanol from the top of the tower, and the second preheater preheats the methanol-ethanol-water ternary mixed solution.

[0014] Furthermore, a second reboiler is connected to the bottom of the ethanol distillation tower, and the second reboiler performs a reboiler cycle at the bottom of the ethanol distillation tower; the second reboiler can adjust the bottom temperature of the ethanol distillation tower, so that the light group of the ethanol distillation tower rises, and obtains ethanol with higher purity.

[0015] Furthermore, the water recovery device includes a second bottom extraction pump, which is connected to the bottom outlet of the ethanol distillation tower and is used to extract water from the bottom of the ethanol distillation tower and send it to the sewage treatment system through the second bottom extraction pump.

[0016] The beneficial effects of the utility model are:

[0017] (1) The utility model provides a double-tower distillation separation device for methanol-ethanol-water with simple structure and low operation complexity by arranging a distillation tower, a preheater, a reboiler, a condenser, a reflux tank, a reflux pump, a production condenser and a production pump.

[0018] (2) The utility model separates and purifies the mixed solution by double-tower distillation, first distilling out the light component methanol in the mixed solution, and then distilling out the light component ethanol in the ethanol-water solution by adjusting and optimizing the double-tower process operating parameters.

[0019] (3) The produced liquid at the bottom of the methanol distillation tower of the utility model has residual temperature, which can save the energy consumption of the ethanol distillation tower after being introduced into the ethanol distillation tower. The double distillation tower has low operating energy consumption, which effectively saves resources, reduces the purification cost, avoids the COD content in the wastewater, and alleviates the environmental pressure.

[0020] (4) The utility model can not only save energy, but also maintain the purity of the top and bottom extracts of each tower unchanged, without reducing the product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a structural schematic diagram of Example 1 of the specific implementation method of the utility model.

[0023] In the figure: 1-methanol distillation tower, 2-first preheater, 3-first reboiler, 4-first top condenser, 5-first reflux tank, 6-first reflux pump, 7-first top extraction condenser, 8-first bottom extraction pump, 9-ethanol distillation tower, 10-second preheater, 11-second reboiler, 12-second top condenser, 13-second reflux tank, 14-second reflux pump, 15-second top extraction condenser, 16-second bottom extraction pump. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0025] Example 1

[0026] like Figure 1 As shown, a double-tower distillation separation device for methanol-ethanol-water comprises a methanol distillation tower 1 and an ethanol distillation tower 9. The feed port of the methanol distillation tower 1 is connected to a methanol-ethanol-water ternary mixed solution raw material supply system through a pipeline, the bottom of the methanol distillation tower 1 is connected to the feed port of the ethanol distillation tower 9 through a pipeline, the top of the methanol distillation tower 1 is connected to a methanol recovery device through a pipeline, and the bottom of the ethanol distillation tower 9 is connected to a water recovery device through a pipeline.

[0027] The methanol recovery device includes a first top condenser 4, a first reflux tank 5, a first reflux pump 6, and a first top extraction condenser 7; the top outlet of the methanol distillation tower 1 is connected to the inlet end of the first top condenser 4, the outlet end of the first top condenser 4 is connected to the inlet end of the first reflux tank 5, the outlet end of the first reflux tank 5 is connected to the inlet end of the first reflux pump 6, the outlet end of the first reflux pump 6 is divided into two paths, which are respectively connected to the top of the methanol distillation tower 1 and the inlet end of the first top extraction condenser 7, and the outlet end of the first top extraction condenser 7 is used to output products.

[0028] The ethanol recovery device includes a second top condenser 12, a second reflux tank 13, a second reflux pump 14, and a second top extraction condenser 15; the inlet end of the second top condenser 12 is connected to the top outlet of the ethanol distillation tower 9, the outlet end of the second top condenser 12 is connected to the inlet end of the second reflux tank 13, the outlet end of the second reflux tank 13 is connected to the inlet end of the second reflux pump 14, the outlet end of the second reflux pump 14 is divided into two paths, which are respectively connected to the top of the ethanol distillation tower 9 and the inlet end of the second top extraction condenser 15, and the outlet end of the second top extraction condenser 15 is used to output products.

[0029] A first preheater 2 is provided on a pipeline connecting the feed port of the methanol distillation tower 1 with the methanol-ethanol-water ternary mixed solution raw material supply system. The first preheater 2 includes a cold end feed port and a cold end discharge port. The cold end feed port of the first preheater 2 is connected to the methanol-ethanol-water ternary mixed solution raw material supply system. The solution temperature is increased by steam heating and discharged from the cold end discharge port. The cold end discharge port of the first preheater 2 is connected to the feed port of the methanol distillation tower 1 for preheating the methanol-ethanol-water ternary mixed solution.

[0030] A first reboiler 3 is provided at the bottom of the methanol distillation tower 1 for performing a reboil cycle at the bottom of the tower.

[0031] A first bottom extraction pump 8 and a second preheater 10 are provided on a pipeline connecting the bottom of the methanol distillation tower 1 and the feed inlet of the ethanol distillation tower 9 .

[0032] A second reboiler 11 is connected to the bottom of the ethanol distillation tower 9 , and the second reboiler 11 performs a reboiling cycle at the bottom of the ethanol distillation tower 9 .

[0033] The water recovery device includes a second bottom extraction pump 16, which is connected to the bottom outlet of the ethanol distillation tower 9 and is used to extract water from the bottom of the ethanol distillation tower 9 and send it to the sewage treatment system through the second bottom extraction pump 16.

[0034] The workflow of this utility model is:

[0035] (1) The methanol-ethanol-water ternary mixed solution is preheated by the first preheater 2 and then enters the methanol distillation tower 1. The theoretical number of plates of the methanol distillation tower 1 is 33-38. The liquid inlet is located at the 14th to 17th plates. The top temperature of the tower is set at 65-68°C and the bottom temperature is set at 90-95°C. The first reboiler 3 is heated by steam, and the light component of the methanol distillation tower 1 is extracted at the top of the tower, condensed by the first top condenser 4 and enters the first reflux tank 5. The first reflux tank 5 is sampled to detect the methanol concentration, and qualified methanol is extracted from the first top extraction condenser 7, and part of the unqualified methanol enters the tower for repeated distillation.

[0036] (2) The bottom components of methanol distillation tower 1 are preheated by second preheater 10 and then enter ethanol distillation tower 9. The theoretical number of plates of ethanol distillation tower 9 is 17-25. The liquid inlet is located at the 5th to 7th plates. The top temperature is 78-82°C and the bottom temperature is 95-99°C. The outlet temperature of second top extraction condenser 15 is 78°C. The venting regulating valve of second top condenser 12 is adjusted by top pressure to control the venting pressure at normal pressure and the venting temperature at 37-39°C. The second reboiler 11 is heated by steam, and the light components of ethanol distillation tower 9 are extracted at the top of the tower, condensed by second top condenser 12 and enter second reflux tank 13. The ethanol concentration is tested by sampling from second reflux tank 13, and qualified ethanol is extracted from second top extraction condenser 15. Some unqualified ethanol enters the tower for repeated distillation.

[0037] (3) The bottom water of the ethanol distillation tower 9 is extracted through the second bottom extraction pump 16 and sent to the sewage treatment system.

[0038] Although the present invention is described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person skilled in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person skilled in the art who is familiar with the present technical field may easily think of changes or substitutions within the technical scope disclosed in the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A double-tower distillation device for separating methanol-ethanol-water, characterized in that: It includes a methanol distillation tower and an ethanol distillation tower, wherein the feed port of the methanol distillation tower is connected to a methanol-ethanol-water ternary mixed solution raw material supply system through a pipeline, the bottom of the methanol distillation tower is connected to the feed port of the ethanol distillation tower through a pipeline, the top of the methanol distillation tower is connected to a methanol recovery device through a pipeline, and the bottom of the ethanol distillation tower is connected to a water recovery device through a pipeline; The methanol recovery device comprises a first tower top condenser, a first reflux tank, a first reflux pump, and a first tower top extraction condenser; the tower top outlet of the methanol distillation tower is connected to the inlet end of the first tower top condenser, the outlet end of the first tower top condenser is connected to the inlet end of the first reflux tank, the outlet end of the first reflux tank is connected to the inlet end of the first reflux pump, the outlet end of the first reflux pump is divided into two paths, which are respectively connected to the tower top of the methanol distillation tower and the inlet end of the first tower top extraction condenser, and the outlet end of the first tower top extraction condenser is used to output products; The ethanol recovery device includes a second top condenser, a second reflux tank, a second reflux pump, and a second top extraction condenser; the inlet end of the second top condenser is connected to the top outlet of the ethanol distillation tower, the outlet end of the second top condenser is connected to the inlet end of the second reflux tank, the outlet end of the second reflux tank is connected to the inlet end of the second reflux pump, the outlet end of the second reflux pump is divided into two paths, which are respectively connected to the top of the ethanol distillation tower and the inlet end of the second top extraction condenser, and the outlet end of the second top extraction condenser is used to output products.

2. A double-tower distillation device for separating methanol-ethanol-water as claimed in claim 1, characterized in that: A first preheater is provided on a pipeline connecting the feed inlet of the methanol distillation tower and the methanol-ethanol-water ternary mixed solution raw material supply system.

3. A double-tower distillation device for separating methanol-ethanol-water as claimed in claim 1, characterized in that: A first reboiler is provided at the bottom of the methanol distillation tower.

4. A double-tower distillation separation device for methanol-ethanol-water as claimed in claim 1, characterized in that: A first bottom extraction pump and a second preheater are arranged on a pipeline connecting the bottom of the methanol distillation tower and the feed inlet of the ethanol distillation tower.

5. The double-tower distillation separation device for methanol-ethanol-water according to claim 1, characterized in that: The bottom of the ethanol distillation tower is connected with a second reboiler.

6. A double-tower distillation separation device for methanol-ethanol-water as claimed in claim 1, characterized in that: The water recovery device comprises a second tower bottom extraction pump, and the second tower bottom extraction pump is connected to the tower bottom outlet of the ethanol distillation tower.

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