Mobile membrane embedded coupling rectification device

Abstract

The utility model belongs to the technical field of chemical engineering, and mainly relates to a movable membrane embedded coupling rectification device and a separation method thereof for a binary water-containing lowest azeotropic system. According to the utility model, the purification process of the binary water-containing lowest azeotropic system is simplified to the equipment in which the rectifying tower and the membrane component are embedded and coupled, so that the rectification equipment investment and the rectification energy cost are greatly reduced, and the integration of the rectification-membrane coupling process device is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical engineering, and mainly relates to a mobile membrane embedded coupled distillation device and a separation method thereof for a binary water-containing minimum azeotropic system. Background Art

[0002] Azeotrope refers to a liquid mixture of two or more components, whose components and boiling point remain unchanged when boiling under constant pressure. The mixture has a large positive deviation from Raoult's law and may form a minimum azeotrope. Most azeotropes are minimum azeotropes, that is, they have the lowest boiling point. When the azeotropic system reaches its azeotropic point, ordinary distillation cannot effectively separate the azeotropic system because the vapor phase and liquid phase produced by its boiling have exactly the same composition. For this purpose, special distillation is required, such as azeotropy, extraction, salt addition, pressure swing distillation and other processes. Although these processes can effectively separate the azeotropic system and obtain high-purity products, they are accompanied by high energy consumption and equipment investment. At the same time, because the introduction of the third component is easy to put greater pressure on environmental protection, it does not conform to the current development trend of green chemical industry.

[0003] Membrane separation technology is not limited by thermodynamics and vapor-liquid equilibrium. It has the technical advantages of high efficiency, energy saving and environmental friendliness. It is known as one of the most promising high-tech technologies in the chemical industry in the 21st century. Membrane separation technology has obvious advantages in separating near-boiling and azeotropic systems. It is simple to operate and easy to control. It is widely used in petrochemical, food, medicine and other fields. However, industrial raw materials often contain salt and acid impurities, which will have a certain impact on membrane materials. Compared with distillation technology, the membrane processing capacity is relatively small and the membrane material cost is high, which limits the application of membrane separation technology. Coupling distillation with membrane separation technology can combine the advantages of the two technologies and overcome the defects.

[0004] At present, most distillation-membrane couplings adopt external coupling, but this method is more similar to a separation process and cannot fully reflect the advantages of membrane separation. The molecular sieve membrane is coupled to the inside of the tower as a tower internal, which can give full play to the advantages of membrane separation. By adjusting the vapor-liquid composition and flow rate in the tower, the distillation separation effect can be improved and the required energy consumption can be reduced. However, the position of the membrane assembly in the tower in the prior art is fixed, and different coupling positions cannot be adjusted according to different separation systems, thereby limiting the application of the device between different systems. Utility Model Content

[0005] In view of the deficiencies of the prior art, the purpose of the utility model is to provide a mobile membrane embedded coupled distillation device, which can be widely used in the separation of different binary water-containing minimum azeotropic systems.

[0006] The technical solution of this utility model is as follows:

[0007] A mobile membrane embedded coupled distillation device, the device comprises a distillation tower with a multi-section tower section design, a tower top condenser, a tower bottom reboiler, a product tank, a vacuum pump, a hydrophilic membrane component, and a PID control system, the top and bottom of the distillation tower are respectively connected to the tower top condenser and the tower bottom reboiler, the vacuum pump is connected to the membrane component; the PID control system controls the tower bottom temperature and the distillate reflux ratio; the membrane component is located in one of the tower sections of the distillation tower, and the tower section position of the membrane component in the distillation tower can be arbitrarily adjusted.

[0008] Preferably, the distillation tower section is designed with packing or plates.

[0009] Preferably, a vacuum port and a sample detection port are reserved on the tower section where the membrane assembly is located.

[0010] Preferably, the hydrophilic membrane assembly is a molecular sieve membrane assembly, and the molecular sieve membrane is selected from one of NaA, T-type, MOR, CHA, NaY or ZSM-5; the carrier configuration of the molecular sieve membrane is one of sheet type, tubular type or hollow fiber type, and the carrier material is one of alumina, zirconium oxide, titanium oxide, or mullite.

[0011] Preferably, the distillation tower sections and membrane module sections are connected by flanges, and the relative positions between the tower sections can be freely adjusted; the coupling position of the membrane module can be moved to different positions of the stripping section, middle section and distillation section of the distillation tower.

[0012] The advantages of the utility model are:

[0013] The utility model adopts a new type of mobile membrane embedded coupled distillation device, which simplifies the purification process of the binary water-containing minimum azeotropic system to a device with a distillation tower and a membrane component embedded coupled, greatly reducing the investment in distillation equipment and the distillation energy cost, improving the integration of the distillation-membrane coupling process device, and further saving the floor space. And taking advantage of the membrane separation is not limited by thermodynamics and vapor-liquid equilibrium, the membrane component is coupled to the inside of the distillation to purify the vapor-liquid two-phase in the tower, promoting the positive deviation of the vapor-liquid two-phase composition distribution, broadening the distillation boundary, and improving the distillation separation effect.

[0014] The positions of the tower section of the membrane component of the utility model and other tower sections can be freely adjusted according to the process simulation results, and the influence of different coupling positions of the membrane component on the separation performance of the device can be examined to determine the best coupling position, and different coupling positions can be optimized according to different azeotropic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1The mobile membrane embedded coupled distillation device and the schematic diagram of the experimental process applied to ethanol / water in Example 1 and propylene glycol monomethyl ether / water in Example 2 are shown in the figure: 1-distillation tower kettle; 2-first tower section; 3-second tower section; 4-molecular sieve membrane assembly; 5-third tower section; 6-tower head; 7-tower top condenser; 8-product tank; 9-cold trap; 10-vacuum pump. DETAILED DESCRIPTION

[0016] Embodiment 1:

[0017] A specific implementation experiment case of a mobile membrane embedded coupled distillation device for separation of ethanol / water binary system. Take the feed mass of 4.17kg, feed composition of 80wt.% ethanol (Ethanol), 20wt.% water (Water) as an example, and the membrane area is 0.081m 2 , the schematic diagram of the device is as follows Figure 1 As shown, a distillation tower including a three-section tower section design (including a first tower section 2, a second tower section 3 and a third tower section 5), a tower top condenser 7, a tower bottom reboiler 1, a product tank 8, a vacuum pump 10, a molecular sieve membrane module 4, and a PID control system, wherein the tower head 6 and the tower bottom of the distillation tower are respectively connected with the tower top condenser 7 and the tower bottom reboiler 1, and the vacuum pump 10 is connected to the membrane module 4 through a cold trap; the PID control system controls the tower bottom temperature and the distillate reflux ratio; the membrane module is located in one of the tower sections of the distillation tower, and the position of the tower section of the distillation tower where the membrane module is located can be adjusted arbitrarily. The tower section of the distillation tower adopts a tower plate design. A vacuum port and a sample detection port are reserved on the tower section where the membrane module is located. The tower section of the distillation tower and the tower section of the membrane module are connected by flanges, and the relative positions between the tower sections can be freely adjusted; the coupling position of the membrane module can be moved to different positions of the stripping section, the middle section and the distillation section of the distillation tower.

[0018] The above device was used for ethanol / water separation. When the steam permeation device was not turned on, the reflux ratio was set to 4, and the distillation device distilled 412.08g of product per hour, and the ethanol content in the product was 94.50wt.%. The steam permeation device was turned on, and the NaA molecular sieve membrane was coupled to the middle section of the distillation tower. The mass of the distillate was 419.06g per hour, and the ethanol content in the product was 96.34wt.%. Compared with the former, the mass of the distillate was almost the same, but the ethanol content in the product increased by 1.84wt.%. The coupling position was changed to the upper section of the distillation tower, and the mass of the distillate was 414.47g per hour, and the ethanol content in the product was 96.85wt.%, which was 2.35wt.% and 0.51wt.% higher than that in the uncoupled and middle section coupled states, respectively. The results are shown in Table 1.

[0019] Table 1 Comparison of distillate quality and ethanol content of three coupling methods

[0020]

[0021] Embodiment 2:

[0022] A specific implementation experiment case of a mobile membrane embedded coupled distillation device for separating propylene glycol monomethyl ether (PM) / water azeotropic system. Taking the feed mass of 4.78kg, feed composition of 70wt.% (PM), 30wt.% (Water) as an example, the membrane area is 0.081m 2 , the schematic diagram of the device is as follows Figure 1 shown.

[0023] The new mobile membrane embedded coupled distillation device is used for propylene glycol monomethyl ether / water separation. When the steam permeation device is not turned on, the reflux ratio is set to 3, and the distillation device distills 376.57g of product per hour, and the PM content in the product is 52.37wt.%. The steam permeation device is turned on, and the T-type molecular sieve membrane is coupled to the middle section of the distillation tower. The mass of the distillate is 380.64g per hour, and the PM content in the product is 53.97wt.%. Compared with the former, the mass of the distillate is almost the same, but the PM content in the product increases by 1.6wt.%. The coupling position is changed to the upper section of the distillation tower. The mass of the distillate is 363.45g per hour, and the PM content in the product is 55.18wt.%, which is 2.81wt.% and 1.21wt.% higher than that in the uncoupled and middle section coupled states, respectively. The results are shown in Table 2.

[0024] Table 2 Comparison of distillate quality and PM content of three coupling methods

[0025]

[0026] Through experiments, the feasibility of using this new type of mobile membrane embedded coupled distillation device for the separation of binary azeotropic systems such as ethanol / water and propylene glycol monomethyl ether / water was demonstrated, and the influence of the coupling position on the distillation separation effect was investigated. It was determined that coupling the molecular sieve membrane to the upper section of the distillation tower can cross the azeotropic point of the azeotrope and have the best separation effect.

Claims

1. A mobile membrane embedded coupled distillation device, characterized in that: The device comprises a distillation tower with a multi-section tower section design, a tower top condenser, a tower bottom reboiler, a product tank, a vacuum pump, a hydrophilic membrane component, and a PID control system. The top and bottom of the distillation tower are respectively connected to the tower top condenser and the tower bottom reboiler, and the vacuum pump is connected to the membrane component; the PID control system controls the tower bottom temperature and the distillate reflux ratio; the membrane component is located in one of the tower sections of the distillation tower, and the tower section position of the membrane component in the distillation tower can be arbitrarily adjusted.

2. The device according to claim 1, characterized in that: The tower sections of distillation towers are designed with packing or plates.

3. The device according to claim 1, characterized in that: A vacuum port and a sample detection port are reserved on the tower section where the membrane assembly is located.

4. The device according to claim 1, characterized in that: The hydrophilic membrane assembly is a molecular sieve membrane assembly, and the molecular sieve membrane is selected from one of NaA, T-type, MOR, CHA, NaY or ZSM-5; the carrier configuration of the molecular sieve membrane is one of sheet type, tube type or hollow fiber type, and the carrier material is one of alumina, zirconium oxide, titanium oxide, or mullite.

5. The device according to claim 1, characterized in that: The distillation tower sections and membrane module sections are connected by flanges, and the relative positions between the tower sections can be freely adjusted; the coupling position of the membrane module can be moved to different positions of the stripping section, middle section and distillation section of the distillation tower.

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