阅读说明：本技术 四氢呋喃脱水精制方法 (Tetrahydrofuran dehydration refining method ) 是由 李砚硕 李伟 何定兵 李辉 于 2020-07-27 设计创作，主要内容包括：本发明提供了四氢呋喃脱水精制方法,包括下述步骤：原料以2600～3000kg/h的质量流率输送至热交换设备进行预热,预热至90～130℃后进入操作压力大于绝压0.2MPa的膜分离组件中进行脱水；脱水后的膜渗余侧溶剂通过精馏单元继续分离,得到四氢呋喃产品；从精馏单元采出的成品甲苯先被输送至热交换设备与原料进行换热,经冷却后得到甲苯产品。使用本发明方法进行四氢呋喃脱水精制,无需再对蒸汽渗透膜装置产生的渗透液废水进行回收,降低了能耗,回收液中的水分无需再次进行脱水,提高了单程脱水效率,节约了蒸汽消耗和系统固定投资。常压塔塔顶得到的少量含水溶剂,再次循环回到前端膜分离装置,实现了水分的完全脱除。(The invention provides a tetrahydrofuran dehydration refining method, which comprises the following steps: conveying the raw materials to heat exchange equipment at a mass flow rate of 2600-3000 kg/h for preheating, and dewatering the raw materials in a membrane separation assembly with an operating pressure of more than 0.2MPa after the raw materials are preheated to 90-130 ℃; continuously separating the dehydrated solvent on the membrane retentate side through a rectification unit to obtain a tetrahydrofuran product; and conveying the finished toluene extracted from the rectification unit to heat exchange equipment to exchange heat with the raw material, and cooling to obtain a toluene product. The method is used for tetrahydrofuran dehydration and refining, penetrating fluid wastewater generated by the vapor permeation membrane device does not need to be recycled, the energy consumption is reduced, moisture in the recycled liquid does not need to be dehydrated again, the one-way dehydration efficiency is improved, and the steam consumption and the system fixed investment are saved. And a small amount of aqueous solvent obtained from the top of the atmospheric tower is recycled to the front-end membrane separation device again, so that the complete removal of water is realized.)

1. The tetrahydrofuran dehydration refining method is characterized by comprising the following steps: conveying the raw materials to heat exchange equipment at a mass flow rate of 2600-3000 kg/h for preheating, and dewatering the raw materials in a membrane separation assembly with an operating pressure of more than 0.2MPa after the raw materials are preheated to 90-130 ℃; continuously separating the dehydrated solvent on the membrane retentate side through a rectification unit to obtain a tetrahydrofuran product;

and conveying the finished toluene extracted from the rectification unit to heat exchange equipment to exchange heat with the raw material, and cooling to obtain a toluene product.

2. The method according to claim 1, wherein the raw material comprises 3-15 wt% of water, 5-20 wt% of toluene and 70-80 wt% of tetrahydrofuran.

3. The method of claim 1, wherein the feed preheat temperature is 110 ± 2 ℃.

4. The method according to claim 1, wherein the membrane separation module is operated at a pressure of 0.2 to 0.4 MPa.

5. The method of claim 1, wherein the rectification unit comprises a primary rectification module and a secondary rectification module, wherein the primary rectification module comprises a first separation column and the secondary rectification module comprises a second separation column.

6. The method according to claim 4, wherein the first separation tower is operated under normal pressure, the tower top temperature is 60-66 ℃, the tower bottom temperature is 70-80 ℃, and the tower top reflux ratio is 0.5-3.

7. The method as claimed in claim 4, wherein the second separation tower is operated under a pressure of 0.2-0.6 MPa, the tower top temperature is 100-110 ℃, the tower bottom temperature is 150-170 ℃, and the reflux ratio at the tower top is 0.3-3.

8. The method according to claim 1, wherein the method uses a tetrahydrofuran dehydration refining apparatus comprising a membrane separation unit and a rectification unit, wherein: the membrane separation unit comprises a first heat exchange device (1) and a membrane separation assembly (2);

wherein the first heat exchange device (1) is provided with a raw material inlet, a raw material outlet, a heat exchange medium inlet and a heat exchange medium outlet; the membrane separation component (2) is provided with a raw material inlet, a retentate outlet and a permeate outlet;

the retentate outlet of the membrane separation module (2) is connected with a rectification unit; and a material outlet of the rectifying unit is connected with a heat exchange medium inlet of the first heat exchange device (1).

9. The method of claim 8, wherein: the device comprises a membrane separation dehydration unit and a rectification unit, wherein the membrane separation unit comprises a first heat exchange device (1), a membrane separation assembly (2) and a permeate treatment assembly (9); the rectification unit comprises a first separation tower (3), a second heat exchange device (5), a third heat exchange device (6), a second separation tower (4), a fourth heat exchange device (7) and a fifth heat exchange device (8);

wherein the first heat exchange device (1) is provided with a raw material inlet, a raw material outlet, a heat exchange medium inlet and a heat exchange medium outlet; the membrane separation component (2) is provided with a raw material inlet, a retentate outlet and a permeate outlet;

the retentate outlet of the membrane separation module (2) is connected with a rectification unit; a material outlet of the rectification unit is connected with a heat exchange medium inlet of the first heat exchange device (1); the second heat exchange device (5) is also connected with the first heat exchange device (1); the third heat exchange device (6) is also connected with the top steam outlet of the second separation tower (4); the fifth heat exchange device (8) is also connected with the third heat exchange device (6).

10. The method of claim 9, comprising the steps of:

(1) mixing a raw material containing 3-15 wt% of water, 5-20 wt% of toluene and 70-80 wt% of tetrahydrofuran with a material extracted from the top of the first separation tower (3), and conveying the mixture to heat exchange equipment at a mass flow rate of 2700-3300 kg/h for preheating until the temperature is 110 +/-2 ℃, wherein a heat source used for preheating is finished toluene from a separation unit; the preheated raw materials enter a membrane separation component (2) for dehydration, and the operation pressure is 0.2-0.4 MPa of absolute pressure; the permeate is directly discharged after passing through a permeate treatment component (9);

(2) the dehydrated retentate enters a first separation tower (3) for separation, part of steam extracted from the top of the first separation tower (3) flows back to the first separation tower (3) to continue to participate in the reaction after heat exchange of second heat exchange equipment (3), and part of steam is conveyed to a raw material inlet of the first heat exchange equipment (1) to participate in the reaction; the first separation tower (3) is operated under normal pressure, the temperature of the top of the tower is 60-66 ℃, the temperature of a tower kettle is 70-80 ℃, and the reflux ratio of the top of the tower is 1 +/-0.2;

(3) materials extracted from the bottom of the first separation tower (3) are conveyed to a second separation tower (4) for continuous separation, steam extracted from the top of the second separation tower (4) is conveyed to a third heat exchange device (6) for providing a heat source, part of the materials after heat exchange returns to the top of the second separation tower (4) for continuous reaction, and part of the materials pass through a fifth heat exchange device (8) for extracting finished product tetrahydrofuran; the second separation tower (4) adopts pressurization operation, the absolute pressure of the operation pressure is 0.2-0.6 MPa, the tower top temperature is 100-110 ℃, the tower kettle temperature is 150-170 ℃, and the reflux ratio of the tower top is 0.5 +/-0.2;

(4) materials extracted from the tower bottom of the second separation tower (4) are subjected to heat exchange through a fourth heat exchange device (7), then flow back to the second separation tower (4) to continuously participate in the reaction, and finished toluene is conveyed from the tower bottom to the first heat exchange device (1) to provide a heat source and then is condensed and extracted.

Technical Field

The invention belongs to the field of dehydration and refining processes of mixed organic solvents, and particularly relates to a tetrahydrofuran dehydration and refining method.

Background

Tetrahydrofuran is a heterocyclic organic compound, belongs to ethers, and is a complete hydrogenation product of aromatic compound furan. The liquid is colorless and low-viscosity transparent liquid, has the smell similar to that of diethyl ether, has the characteristics of low toxicity, low boiling point, good fluidity and the like, is an important organic chemical and fine chemical raw material, and is mainly used for producing polytetramethylene ether glycol (PTMEG), polyurethane elastic fibers, elastomers, polyurethane artificial leather and the like. With the rapid increase of domestic demand for polyurethane elastic fibers and elastomers, the demand for tetrahydrofuran will also increase rapidly.

In the mixed solvent system of tetrahydrofuran, one or more solvents form binary azeotropic system or multi-azeotropic system with tetrahydrofuran, so that the purification and refining of the mixed solvent become complicated. The conventional rectification method has high energy consumption and complex process, and a third component is required to be added for an azeotropic system, so that the recovered solvent contains impurities, and the purity and the use quality of the product are influenced.

The membrane separation technology taking the steam permeation dehydration membrane as the core takes the steam partial pressure difference of the removed components as the driving force, shows great advantages in the field of organic solvent dehydration, has simple process route and low energy consumption, does not introduce a third component, and has high product purity. As for a tetrahydrofuran mixed solvent system used in the fine chemical industry, the system is complex and contains certain impurities, an efficient, reliable and energy-saving process needs to be found, and the problems of high energy consumption and low product purity of conventional rectification are solved.

Disclosure of Invention

The invention aims to provide a method for dehydrating and refining tetrahydrofuran and discloses a set of low-energy-consumption integrated device for dehydrating and refining tetrahydrofuran, which is suitable for the method.

The tetrahydrofuran dehydration refining method comprises the following steps: conveying the raw materials to heat exchange equipment at a mass flow rate of 2600-3000 kg/h for preheating, and dewatering the raw materials in a membrane separation assembly with an operating pressure of more than 0.2MPa after the raw materials are preheated to 90-130 ℃; continuously separating the dehydrated solvent on the membrane retentate side through a rectification unit to obtain a tetrahydrofuran product; and conveying the finished toluene extracted from the rectification unit to heat exchange equipment to exchange heat with the raw material, and cooling to obtain a toluene product.

In order to fully implement the above-mentioned tetrahydrofuran dehydration and purification method of the present invention, the present invention further provides a set of tetrahydrofuran dehydration and purification apparatus suitable for the above-mentioned method, comprising a membrane separation unit and a rectification unit, wherein: the membrane separation unit comprises a first heat exchange device and a membrane separation assembly; the first heat exchange equipment is provided with a raw material inlet, a raw material outlet, a heat exchange medium inlet and a heat exchange medium outlet; the membrane separation component is provided with a raw material inlet, a retentate outlet and a permeate outlet; a retentate outlet of the membrane separation assembly is connected with a rectification unit; and a material outlet of the rectifying unit is connected with a heat exchange medium inlet of the first heat exchange device. The method for implementing dehydration and purification of tetrahydrofuran by using the device comprises the following steps: the raw material enters first heat exchange equipment for preheating, and a heat source used for preheating is provided by a heat exchange medium; the preheated raw material enters a membrane separation component for dehydration, the retentate obtained by the separation of the membrane separation unit enters a rectification unit, tetrahydrofuran steam and toluene material are extracted from the rectification unit, the tetrahydrofuran steam is collected into qualified tetrahydrofuran finished product after being condensed, and the toluene material enters a first heat exchange device as a heat exchange medium and is collected into toluene finished product after being subjected to heat exchange with the raw material.

The method of the invention is used for tetrahydrofuran dehydration refining, and the adopted mixed solvent dehydration refining process does not need to further recover penetrating fluid wastewater generated by the steam permeable membrane device, thus reducing the energy consumption, and the moisture in the recovered liquid does not need to enter the membrane separation device again for dehydration, improving the one-way dehydration efficiency, and saving the steam consumption and the system fixed investment. And a small amount of aqueous solvent obtained from the top of the atmospheric tower is recycled to the front-end membrane separation device again, so that the complete removal of water is realized.

Drawings

FIG. 1 is a schematic flow diagram of a tetrahydrofuran dehydration purification apparatus of the present invention, wherein:

1. a first heat exchange device; 2. a membrane separation module; 3. a first separation column; 4. a second separation column; 5. a second heat exchange device; 6. a third heat exchange device; 7. a fourth heat exchange device; 8. a fifth heat exchange device; 9. a permeate processing module.

Detailed Description

The following detailed description of the invention refers to the accompanying drawings.

The invention provides a tetrahydrofuran dehydration refining method, which comprises the steps that raw materials enter a membrane separation component for dehydration after being preheated; continuously separating the dehydrated solvent on the membrane retentate side through a rectification unit to obtain a tetrahydrofuran product; and conveying the finished toluene extracted from the rectification unit to heat exchange equipment to exchange heat with the raw material, and cooling to obtain a toluene product.

In order to better carry out the method of the present invention described above, in a specific embodiment of the present invention, there is provided a tetrahydrofuran dehydration purification apparatus which is used exclusively for the method using the same. Wherein the tetrahydrofuran dehydration refining plant that says includes membrane separation unit and rectification unit, wherein: the membrane separation unit comprises a first heat exchange device 1 and a membrane separation assembly 2; wherein the first heat exchange device 1 is provided with a raw material inlet, a raw material outlet, a heat exchange medium inlet and a heat exchange medium outlet; the membrane separation component 2 is provided with a raw material inlet, a retentate outlet and a permeate outlet; the retentate outlet of the membrane separation module 2 is connected with a rectification unit; and a material outlet of the rectifying unit is connected with a heat exchange medium inlet of the first heat exchange device 1.

The tetrahydrofuran raw material to be treated enters a membrane separation unit after being preheated, and the membrane separation process is carried out. Water molecules penetrate through the molecular sieve membrane to form a permeate, and the permeate is discharged out of the system through the membrane separation unit. The toluene tetrahydrofuran with larger molecular size is intercepted by the molecular sieve membrane and enters a rectification unit, and the toluene and tetrahydrofuran products are separated. And in the system design, heat exchange is formed between the product and the raw materials so as to recycle the heat source of the product to realize the heating of the raw materials.