WO2020173510A2

WO2020173510A2 - Hollow fibre pervaporation membrane-based glycerol concentration device and method

Info

Publication number: WO2020173510A2
Application number: PCT/CN2020/087360
Authority: WO
Inventors: 唐宇攀; 刘军; 汪旺华
Original assignee: 南京惟新环保装备技术研究院有限公司
Priority date: 2019-02-28
Filing date: 2020-04-28
Publication date: 2020-09-03
Also published as: CN109809965A; CN109809965B; WO2020173510A3

Abstract

Provided are a hollow fibre pervaporation membrane-based glycerol concentration method and device. The method uses an innovative hollow fibre pervaporation membrane to perform dehydration and concentration on crude glycerol, the hollow fibre pervaporation membrane has high water permeability, and the flux can reach 5-10 times that of a crosslinked polyvinyl alcohol membrane and 2-5 times that of an inorganic membrane. The hollow fibre pervaporation membrane has no requirements for the water content of a feed solution and has a wide tolerance range for pH and conductivity. Therefore, the present process can replace traditional energy-consuming processes such as reduced pressure multi-stage distillation, and can be used directly for performing dehydration and concentration on a feed solution having a high water content, thereby significantly decreasing production energy consumption, reducing device investment costs, and thus reducing glycerol production costs. Operational costs can be reduced by more than 50% compared to traditional processes. In addition, the concentration temperature of the present process is lower than 100°C, thereby avoiding glycerol decomposition and polymerisation to a large extent, reducing by-products, and increasing product quality.

Description

Glycerin concentration equipment and method based on hollow fiber pervaporation membrane Technical field

The present invention relates to the field of glycerol preparation, and in particular to a glycerol concentration equipment and method based on a hollow fiber pervaporation membrane. Background technique

Glycerin has a wide range of uses in industries such as medicine, coatings, textiles, papermaking, cosmetics, food, tanning, electrical materials and rubber.

At present, the industrial production methods of glycerin are mainly divided into two categories: 1. Natural glycerin prepared from natural fats and oils as raw material; 2. Synthetic glycerin prepared from propylene as raw material. Glycerin synthesized by the above two methods The water content of glycerin is above 70-80%. Therefore, dehydrating and concentrating glycerin is an important part of obtaining high-purity glycerin. The dehydration effect directly affects the quality of the final glycerin. In addition, the recovery of glycerin-containing waste liquid produced in industrial applications is also a very important market demand. At present, the main method of removing water from glycerol is distillation. However, due to the high boiling point of glycerol (293 ^° C), and above 202 V, it will decompose into acrolein and deteriorate, or polymerize into polyglycerol. Therefore, complex vacuum multi-stage distillation is usually required in actual operation. Although the vacuum multi-stage distillation method can achieve dehydration and concentration of glycerin, its shortcomings are very obvious: First, the equipment is complicated, because of the instability of glycerol at high temperatures, the equipment control and operation requirements are very delicate; second, the equipment occupies a large area Third, the energy consumption is very high. Because of its high boiling point, the temperature of vacuum distillation is above 150 ^° C. Fourth, the product purity is low. As mentioned earlier, glycerin is very sensitive to temperature, even if the temperature is 150- Under the conditions of vacuum distillation at 180 ^° C, there will still be a small amount of glycerol quality change; fifth, the environmental impact is great. Pervaporation, as a simple and energy-saving cutting-edge technology, can provide an efficient way to concentrate in the preparation and recovery of glycerol. However, the current inorganic pervaporation membrane materials on the market have many restrictions: (1) The water content of the original solution cannot exceed 20%; (2) It is very sensitive to impurities, conductivity, pH, etc., and the selective layer is easily divided by acid, alkali, salt, etc. Damage; (3) Glycerol is easy to block the selective layer of the inorganic pervaporation membrane due to its high viscosity characteristics, so that the membrane separation performance is rapidly reduced. Therefore, there is currently no suitable pervaporation membrane on the market that can be used for the dehydration and concentration of glycerol, and there are no relevant case studies in industry and academia. Summary of the invention

The purpose of the present invention is to provide a glycerol concentration equipment and method based on a hollow fiber pervaporation membrane, which is a brand-new glycerol concentration process, and the use of an original pervaporation membrane can treat high-water content C The triol solution is dehydrated and concentrated to completely replace the multi-stage vacuum distillation technology, so that the energy consumption of the glycerol concentration process is greatly reduced, and the product quality is greatly improved, and the equipment is simple and has the advantages of small footprint and low environmental impact.

In order to achieve any of the above invention objectives, the present invention provides a hollow fiber pervaporation membrane-based glycerol concentration method, which includes the following steps:

S 1: Containing 20%-50% glycerin crude liquid ultrafiltration filtering TSS suspended impurities to obtain a filtered clear liquid;

S2: heating and filtering the clear liquid;

S3: Use a hollow fiber pervaporation membrane to dehydrate, concentrate and filter the clear liquid to obtain recovered glycerol. Wherein, in step S1, the crude liquid containing 20%-50% of glycerol first enters the ultrafiltration unit to filter out TSS suspended impurities, where the TSS suspended impurities include cellulose, lignin, protein, suspended particles, etc., the ultrafiltration The unit is implemented as an ultrafiltration membrane, the ultrafiltration membrane is an inorganic ceramic membrane or an organic membrane, and the ultrafiltration membrane is selected from hollow fiber membranes, plate membranes, single-channel tubular membranes or multi-channel tubular membranes. The pore size of the membrane is 0.01-0. 2 microns. When the ultrafiltration membrane is a ceramic ultrafiltration membrane, the pore size of the ceramic ultrafiltration membrane 01-0. 1 micron; when the ultrafiltration membrane is an organic ultrafiltration membrane, the organic ultrafiltration membrane is a hollow fiber membrane, the pore size is 0.01-0. 05 microns, the operating pressure is 0. l -3bar, the purpose of this step is to filter the TSS suspended impurities and protect the pervaporation unit;

Wherein, in step S2, the filtered clear liquid obtained in step S1 is collected in a buffer tank, and the filtered clear liquid is heated to a set temperature of 60-100 ^° C through a preheater and a heater. It is worth mentioning that in the present invention , The heating temperature of the filtered clear liquid does not exceed 100 degrees Celsius. Therefore, it is guaranteed that the glycerol solution with high water content can be dehydrated and concentrated at less than 100 degrees Celsius, so as to prevent the glycerol from becoming malonaldehyde under high temperature environments. As well as impurities such as polyglycerol, ensure the purity and quality of the final product.

Among them, in step S3, an original hollow fiber pervaporation membrane is used to pervaporate and dehydrate the heated filtered supernatant. It is worth mentioning that the hollow fiber pervaporation membrane used in the present invention sequentially forms the inner membrane from the inside to the outside of the membrane. A layer support layer, a selective separation layer and an outer protective layer, wherein the selective separation layer is placed between the inner support layer and the outer protective layer, and the outer protective layer is hydrophilic; and 1-0. 2mm。 The membrane outer diameter of the membrane is 0.8-1. 5mm, the inner diameter is 0.5-1. 2mm, and the wall thickness is 0.1-0. 2mm.

In addition, in step S3, the hollow fiber pervaporation membrane constitutes a pervaporation module, and the permeate side of the pervaporation module is connected to a vacuum unit to maintain a vacuum degree of 5-30 mbar. The moisture diffuses in the pervaporation membrane to the permeate side and condenses After condensing into liquid in the vessel, it is stored in the permeate tank, and the concentrated glycerol enters the product tank after cooling. The gauge pressure on the intercept side of the pervaporation component is 0-3 bar, and the absolute pressure on the permeate side is 5-30 mbar, the purity of the obtained product is 92-95%. In the embodiment of the present invention, it includes at least 1-15 pervaporation components, preferably 5-15 pervaporation components.

Correspondingly, the present invention provides a glycerin concentration equipment based on a hollow fiber pervaporation membrane, which includes at least an ultrafiltration device, a heating device, a pervaporation device, a condensation device, a conveying device, and a storage device. The conveying device includes an ultrafiltration device and a heating device. The pervaporation device and the condensation device are connected in sequence to complete the dehydration and concentration of glycerol. Specifically, the ultrafiltration device includes at least one ultrafiltration unit, wherein the ultrafiltration unit is composed of an ultrafiltration membrane module and auxiliary equipment. The ultrafiltration membrane is an inorganic ceramic membrane or an organic membrane, and the ultrafiltration membrane is selected from a hollow fiber membrane, a plate membrane, a single-channel tubular membrane or a multi-channel tubular membrane, and the ultrafiltration membrane has a pore size of 0.01 -0. 2 microns. The ultrafiltration unit is used to filter the TSS impurities in the crude liquid, such as lignin, protein, suspended particles, etc., to protect the subsequent pervaporation unit.

The heating device includes at least one preheater and a heater. The waste heat of the preheater is reused, the waste heat of the product is reasonably used to heat the raw material liquid, and the heater functions to heat the material liquid to a specific temperature to increase the pervaporation unit Processing power.

The permeation device includes at least one pervaporation membrane group, and the membrane used in the pervaporation membrane group is an original hollow fiber pervaporation membrane. The hollow fiber pervaporation membrane has high water permeability and can be used at temperatures below 100 degrees Celsius Glycerol is dehydrated efficiently, and the condensing device is a condenser to condense evaporated water.

As shown in Figures 1 and 2, the glycerin concentration equipment may be a continuous operation equipment or an intermittent operation equipment. When it is a continuous operation equipment, the glycerin concentration equipment includes a first delivery pump 1 and an ultrafiltration device connected in sequence. Unit 2, buffer tank 3, preheater 5, heater 6 and pervaporation membrane group 7, wherein the permeate side of the pervaporation membrane group 7 is connected to the vacuum unit 14, and the vacuum unit 14 and the pervaporation membrane group 7 is provided with a second condenser 11, the second condenser 11 is connected to the permeate tank 12, one end of the permeate tank 12 is connected to the third transfer pump 13, the moisture is evaporated from the permeate side of the pervaporation membrane group 7, and is After condensing into liquid in the second condenser 11, it is stored in the permeate tank 12; wherein the intercept side of the pervaporation membrane group 7 is connected to the product tank 9, and a first condenser is provided between the product tank 9 and the pervaporation membrane group 7 8. One end of the product tank 9 is connected to the fourth delivery pump 10. The dehydrated glycerol flows out from the intercept side of the pervaporation membrane group 7, and is condensed into a liquid in the first condenser 8, and then stored in the product tank 9. .

In addition, a second delivery pump 4 is provided between the buffer tank 3 and the preheater 5, and the second delivery pump 4 transports materials into the preheater 5 and the heater 6 for heating. The working process of the whole machine is as follows: Contains 20%-50% Glycine After the crude alcohol liquid enters the ultrafiltration unit 2 to filter out the TSS suspended impurities, the obtained filtered supernatant is buffered in the buffer tank 3; under the action of the second delivery pump 4, it is delivered to the preheater 5 and the heater 6, and is heated to After a certain temperature, it enters the pervaporation membrane group 7; a certain degree of vacuum is given on the permeate side of the pervaporation membrane group 7, water evaporates from the permeate side, and the material flows out from the retention side, and is condensed to obtain dehydrated and concentrated glycerol.

When it is a gap operation equipment, it can only include the liquid tank 3, the heating device 15, the second transfer pump 4, the pervaporation membrane group 7, the second condenser 11, the permeate tank 12 and the vacuum unit 14. At this time, The ultrafiltration unit is not attached to the concentration equipment, and is operated separately.

Specifically, at this time, one side of the material liquid tank 3 is connected to the heating device 15, and one side of the material liquid tank 3 is connected to the pervaporation membrane group 7, wherein the permeation side of the pervaporation membrane group 7 is connected to the vacuum unit 14, and A second condenser 11 is provided between the vacuum unit 14 and the pervaporation membrane group 7, and the second condenser 11 is connected to the permeate tank 12. The moisture is vaporized from the permeate side of the pervaporation membrane group 7, and is in the second After condensing into liquid in the condenser 11, it is stored in the permeate tank 12; the intercept side of the pervaporation membrane group 7 is connected to the material liquid tank 3, and the material liquid transfer pump 4 is arranged between the material liquid tank 3 and the pervaporation membrane group 7 , The glycerol obtained from the concentration of the pervaporation membrane group 7 is sent back to the liquid tank 3.

It is worth mentioning that the hollow fiber pervaporation membrane is used in the present invention, and the hollow fiber pervaporation membrane has a high flux and rejection rate, and the flux can reach 5-10 times that of the cross-linked polyvinyl alcohol membrane. 2-5 times of the hollow fiber pervaporation membrane; the filling area of the membrane module composed of the hollow fiber pervaporation membrane is large, and the unit volume can reach more than 5 times of the plate-and-frame membrane module and 20 times of the tubular membrane module. The specific content of the pervaporation membrane is introduced as follows:

Preparation of the hollow fiber pervaporation membrane:

Step 1: preparing inner layer casting liquid, outer layer casting liquid and core liquid, said inner layer casting liquid, said outer layer casting liquid and said core liquid form a hollow tubular liquid film through a spinneret;

Step 2: The hollow tubular liquid film enters the coagulation bath after passing through the air gap to be solidified by phase change, to obtain Hollow fiber membrane yarn; and

Step 3: Process the hollow fiber membrane filaments to obtain a hollow fiber pervaporation membrane.

Among them, you can choose in the step S3:

Step S31: Soak the hollow fiber filaments with water, replacement liquid and micropore protection liquid in sequence, and then dry them in the air.

Alternatively: freeze-dry the hollow fiber membrane filaments.

In addition, during the preparation process, it is preferable to control the flow rate of the inner layer casting liquid to be 0.1-30ml/min, the outer layer casting liquid flow rate is 0.1-30ml/min, the core liquid flow rate is 0. l_30ml/min, core liquid The temperature of the casting liquid is 5-80 degrees Celsius, the temperature of the spinneret is 5-80 degrees Celsius, the winding wheel speed is 1-50 m/min, and the temperature of the coagulation bath is 5-80 degrees Celsius. Such control of the preparation conditions makes the hollow fiber pervaporation membrane obtained by the present invention compare Other membranes have better performance.

The outer layer casting liquid includes a hydrophilic polymer and a solvent, and the hydrophilic polymer includes but is not limited to sulfonated polysulfone, sulfonated polyphenylsulfone, sulfonated polyethersulfone, and sulfonated polyamide And sulfonated polyimide, polyvinyl alcohol, polyoxyethylene, cellulose, cellulose acetate, hydrolyzed polyacrylonitrile, polyvinylpyrrolidone, chitosan, polyetheramine and polyethyleneimine; the solvent Including but not limited to n-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform;

Wherein, the inner layer casting liquid includes polymer polymers, solvents and additives, wherein the polymer polymers include but are not limited to polysulfone, polyethersulfone, polyphenylsulfone, polyamide, polyimide, and polyimide Amide-imide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polypropylene, polycarbonate, polybenzimidazole, polyurethane; the solvent includes but is not limited to n-methyl-2-pyrrolidone , N,N-dimethylacetamide, dimethylformamide, dimethylsulfoxide, tetrahydrofuran, dichloromethane, chloroform; and the auxiliary agent includes but not limited to polyethylene glycol, ethylene glycol , Glycerol, polyvinylpyrrolidone, water, ethanol, acetone, chlorinated Lithium, lithium bromide, calcium chloride;

Wherein the core liquid includes solvents, non-solvents and auxiliary agents, wherein the auxiliary agents include but are not limited to polyethylene glycol, ethylene glycol, glycerol, polyvinylpyrrolidone, ethanol, acetone, n-butanol, among them The solvent includes but is not limited to n-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethylformamide, dimethylsulfoxide, tetrahydrofuran, dichloromethane, chloroform, the non- The solvent is water.

The structure is as follows:

As shown in Figures 6 and 7, the traditional hollow fiber pervaporation membrane sequentially forms a traditional inner support layer, a traditional transition support layer, and a traditional selective separation layer from the inside to the outside, that is, the traditional selective separation layer is located at this time The outermost layer of the traditional hollow fiber pervaporation membrane is prone to problems such as swelling, chemical decomposition, and physical destruction of the separation layer in practical applications, thereby destroying the membrane structural integrity of the pervaporation membrane and reducing the separation efficiency. The hollow fiber pervaporation membrane provided by the present invention sequentially forms an inner support layer, a selective separation layer, and an outer protective layer from the inside to the outside, that is, the selective separation layer is located in the outer protective layer at this time. For protection, the outer protective layer has good hydrophilicity and avoids problems such as chemical and physical damage. The hollow structure of the hollow fiber pervaporation membrane provided by the present invention is achieved by controlling the formula of the inner layer casting liquid and the outer layer casting liquid. If the compatibility of the inner and outer layers is good, the middle selective separation layer is formed No, if the compatibility of the inner and outer layers is too poor, delamination and peeling of the inner and outer layers will occur, and the separation effect and stability will be poor. The inventors tried multiple formulas and finally determined a series of formulas for the inner layer casting liquid and the outer layer casting liquid, which can make the inner and outer layers reach the ideal state of "semi-compatibility", and the actual hollow fiber penetration The cross-sectional views of the vaporized film are shown in Figures 6 and 7.

The specific selection series of formulas are as follows: The first group of formulas: Outer layer casting liquid formula: a mixture of sulfonated polyphenylsulfone and n_methyl-2-pyrrolidone, wherein the mass ratio of the sulfonated polyphenylsulfone Between 10-35%, the mass ratio of the n-methyl-2-pyrrolidone is 65-90%, and the combined ratio of the two formulas is 100%; Inner layer casting liquid formula: a mixture of polyphenylene sulfone, ethylene glycol and n_methyl-2-P pyrrolidone, wherein the mass ratio of the polyphenylsulfone is 10-30%, and the ethylene glycol The mass ratio of the n-methyl-2-pyrrolidone is between 2-20%, the mass ratio of the n-methyl-2-pyrrolidone is 50-88%, and the combined ratio of the three formulas is 100%; the core liquid formula: n-methyl- 2-pyrrolidone, water and ethylene glycol, wherein the mass ratio of the n-methyl-2-pyrrolidone is 50-99%, the mass ratio of the water is 1-4%, and the mass ratio of the ethylene glycol At 0-10%, the combined ratio of the three formulas is 100%. The second set of formulas: The outer layer casting liquid: a mixed liquid of cellulose acetate and n_methyl-2-pyrrolidone, wherein the mass ratio of the cellulose acetate is between 1-15%, The mass ratio of n_methyl-2-pyrrolidone is 85-99%, and the combined ratio of the two formulas is 100%; the inner layer casting liquid: polyetherimide, polyethylene glycol and n- A mixture of methyl-2-pyrrolidone, wherein the mass ratio of the polyphenylsulfone is 10-30%, the mass ratio of the polyethylene glycol is between 1-10%, and the n-methyl-2 -The mass ratio of pyrrolidone is 60-89%, and the combined ratio of the three formulas is 100%; the core liquid: n-methyl-2-pyrrolidone, water and polyethylene glycol, wherein the n-methyl The mass ratio of -2-pyrrolidone is 50-99%, the mass ratio of the water is 1-40%, the mass ratio of the polyethylene glycol is 0-10%, and the combined ratio of the three formulas is 100% . Outer layer casting liquid formula: a mixture of cellulose acetate acetate and n-methyl-2-pyrrolidone, wherein the mass ratio of the cellulose acetate acetate is between 1-15%, The mass ratio of the n-methyl-2-pyrrolidone is 85-99%, and the combined ratio of the two formulas is 100%; the inner layer casting liquid formula: polyetherimide, ethanol and n-methyl- 2-pyrrolidone mixture, wherein the mass ratio of the polyphenylsulfone is 10-30%, the mass ratio of the ethanol is between 1-10%, and the mass ratio of the n-methyl-2-pyrrolidone is 60-89%, the combined ratio of the three formulas is 100%; Core liquid formula: n-methyl-2-pyrrolidone, water and polyethylene glycol, wherein the mass ratio of n-methyl-2-pyrrolidone is 50-99%, and the mass ratio of water is 1-40 %, the mass ratio of the polyethylene glycol is 0-10%, and the combined ratio of the three formulas is 100%. Compared with the prior art, the beneficial effects of the present invention are:

1. The use of ultrafiltration and pervaporation processes to replace traditional decompression multi-stage distillation and other energy-consuming processes, which greatly reduces the waste of production energy consumption, reduces equipment investment costs, and thereby reduces ethanol production costs. The operating costs are more traditional The process is reduced by more than 50%.

2. The original hollow fiber pervaporation membrane is adopted. The hollow fiber pervaporation membrane has a high flux and rejection rate. The flux can reach 5-10 times that of cross-linked polyvinyl alcohol membranes and 2-5 times that of inorganic membranes. As a result, the processing capacity of the hollow fiber pervaporation membrane is greatly improved, and the separation efficiency is high.

3. The hollow fiber pervaporation membrane has strong tolerance to pH, conductivity and water content, and can directly dehydrate and concentrate crude glycerol with a water content of more than 50-90%.

3. The glycerol concentration equipment provided includes a combination of pervaporation membrane units, heating devices, condensers and other equipment. The equipment investment is small, and it saves space. The corresponding process is simple and practical, and has good practicability.

4. The glycerin product concentrated by this new process is stable. Glycerol is dehydrated and concentrated at a temperature lower than 100 degrees Celsius, without producing malonaldehyde and polyglycerol, without by-products, and with high product recovery rate and minimal impact on the environment.

Description of the drawings

Figure i is an equipment schematic diagram of a glycerin concentration equipment based on a hollow fiber pervaporation membrane according to an embodiment of the present invention.

Figure 2 is a glycerol concentration device based on a hollow fiber pervaporation membrane according to another embodiment of the present invention Schematic diagram of the prepared equipment.

Fig. 3 is a surface morphology diagram of an ultrafiltration membrane according to an embodiment of the present invention.

4 and 5 are schematic diagrams of the structure of an ultrafiltration membrane according to another embodiment of the present invention.

Figures 6 and 7 are schematic diagrams of the hollow fiber pervaporation membrane structure according to an embodiment of the present invention. Figure 8 shows the experimental results of Example 3 according to the present invention.

In the figure: the first delivery pump 1, the ultrafiltration unit 2, the buffer tank 3, the second delivery pump 4, the preheater 5, the heater 6, the pervaporation membrane group 7, the first condenser 8, the product tank 9, and the Four delivery pumps 10, second condenser 11, permeate tank 12, third delivery pump 13, vacuum unit 14, heating device 15.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art fall within the protection scope of the present invention.

It can be understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, and in another embodiment, the number of the element The number can be multiple, and the term "one" cannot be understood as a restriction on the number.

The following describes an example of actual glycerol dehydration and concentration using the hollow fiber pervaporation membrane-based glycerin concentration equipment and method of the present invention:

Example 1:

Take the crude glycerol liquid from a certain manufacturer, the water content is about 80 wt%, and the turbidity is 300 NTU. This is a continuous operation process, as shown in the schematic diagram of the equipment in Figure 1.

The crude glycerol liquid is transported to the ultrafiltration unit 2 by the first delivery pump 1 for filtration. The ultrafiltration membrane is an inorganic ceramic membrane with a pore size of 0.05-0. 1 micron and an operating pressure of 0.1-0. 2bar, Get a clean water content of 80% Liquid, turbidity is less than 10NTU, stored in buffer tank 3. At this time, the recovery rate of the ultrafiltration unit 2 is 97-99%.

The glycerol clear liquid in the buffer tank 3 is heated to 90 °C through the preheater 5 and the heater 6, and is transported to the pervaporation membrane group 7 for dehydration and concentration.

The concentrated product is stored in the product tank 9, and is transported to the use site by the fourth transfer pump 10, and the final product purity is 95 wt%, and the yield is 99%.

The moisture permeates and diffuses to the vacuum test of the pervaporation module 7, liquefies in the condenser 11, is stored in the permeate pipe 12, and is transported by the delivery pump 13 to other places. The vacuum degree of the vacuum pump 14 is set to 20 mbar, and the temperature of the condenser 11 is controlled to be less than 5 ^° C.

Example 2:

Take the waste liquid produced during the use of glycerol in a certain company. The water content is about 70 wt%, and it contains 3% lignocellulose. The turbidity is 500 NTU. This is a continuous operation process, as shown in the schematic diagram of the equipment in Figure 1.

The crude glycerol liquid is transported to the ultrafiltration unit 2 by the first delivery pump 1 for filtration. The ultrafiltration membrane is an organic hollow fiber membrane with a pore size of 0.01-0. 1 micron, an operating pressure of 1 bar, and a water content of 70% of the clear liquid, with a turbidity of less than 10NTU, is stored in buffer tank 3. In this case, to obtain the recovery ultrafiltration unit 2 is 95% _o

The glycerol clear liquid in the buffer tank 3 is heated to 80°C by the preheater 5 and heater 6, and is transported to the pervaporation membrane group 7 for dehydration and concentration.

The concentrated product is stored in the product tank 9 and transported to the use site by the fourth transfer pump 10. The final product purity is 92 wt%, and the recovery rate is greater than 99%.

The moisture permeates and diffuses to the vacuum test of the pervaporation module 7, liquefies in the condenser 11, is stored in the permeate pipe 12, and is transported by the delivery pump 13 to other places. The vacuum degree of the vacuum pump 14 is set to 15-20 mbar, and the temperature of the condenser 11 is controlled to be less than 5 ^° C. Example 3:

Self-prepared 15 kg of glycerol and aqueous solution, at this time, the configured glycerol aqueous solution does not have a water content of about 80 wt%. This is an intermittent operation process, as shown in the schematic diagram of the equipment in Figure 2. Place the glycerol aqueous solution in the material liquid tank 3, turn on the heating device 15, and wait for the temperature of the material liquid to rise to 90 °C. Turn on the delivery pump 4, and the material liquid is delivered to the pervaporation module 7, and then returned to the material liquid tank 3. Turn on the vacuum unit 14, control the vacuum degree to 20mbar, and the temperature of the condenser 11 to be no less than 5 ^° C, to perform dehydration and concentration. Test the water content of the material liquid in the material liquid tank 3, and stop the experiment when the water content drops to about 6 wt%. The change in water content of glycerol is shown in Figure 8. The final product purity is 94wt%, and the yield is about 99% _o

Example 4:

Take 12 kg of waste liquid produced during the use of glycerol from a certain company, with a water content of about 70 wt%, 3% lignocellulose, and a turbidity of 500 NTU. This is an intermittent operation process.

The clear liquid obtained after filtering the glycerin waste liquid is placed in the material liquid tank 3, the heating device 15 is turned on, and the temperature of the material liquid is increased to 90°C. Turn on the delivery pump 4, and the material liquid is delivered to the pervaporation module 7, and then returned to the material liquid tank 3. Turn on the vacuum unit 14, control the vacuum degree to 20mbar, and the temperature of the condenser 11 to be no less than 5 ^° C for dehydration and concentration. Test the water content of the material liquid in the material liquid tank 3, and stop the experiment when the water content drops to about 8 wt%. The final product has a purity of 92.5 wt% and a yield of about 99%.

The present invention is not limited to the above-mentioned best embodiment. Under the enlightenment of the present invention, anyone can derive other products in various forms, but regardless of any changes in its shape or structure, any products that are the same as or similar to the present application Approximate technical solutions fall within the protection scope of the present invention.

Claims

1. A glycerol concentration method based on a hollow fiber pervaporation membrane, characterized in that it comprises the following steps

S1: The crude liquid containing 20%-50% of glycerin is filtered through TSS by ultrafiltration to obtain a filtered clear liquid;

S2: heating and filtering the clear liquid, the heating temperature is controlled at 60-100 ^° C _;

S3: The hollow fiber pervaporation membrane is used to dehydrate, concentrate and filter the clear liquid to obtain recovered 92-95% glycerol, wherein the hollow fiber pervaporation membrane sequentially forms an inner support layer from the inside to the outside of the membrane, and the separation layer is selected And an outer protective layer, wherein the selective separation layer is placed between the inner supporting layer and the outer protective layer, and the outer protective layer is hydrophilic.

2. The glycerol concentration method based on hollow fiber pervaporation membrane according to claim 1, characterized in that the preparation process of the hollow fiber pervaporation membrane is as follows: Step 1: Preparing inner layer casting film and outer layer casting film Liquid and core liquid, the inner layer casting liquid, the outer layer casting liquid and the core liquid form a hollow tubular liquid film through the spinneret; Step 2: The hollow tubular liquid film passes through the air gap and enters to solidify The bath is solidified by phase change to obtain hollow fiber membrane filaments; and step 3: processing the hollow fiber membrane filaments to obtain a hollow fiber pervaporation membrane; wherein the outer layer casting liquid includes a hydrophilic polymer and a solvent, wherein The hydrophilic polymer includes but is not limited to sulfonated polysulfone, sulfonated polyphenylsulfone, sulfonated polyethersulfone, sulfonated polyamide and sulfonated polyimide, polyvinyl alcohol, polyoxyethylene, cellulose, Cellulose acetate, hydrolyzed polyacrylonitrile, polyvinylpyrrolidone, chitosan, polyetheramine and polyethyleneimine; the solvent includes but not limited to n-methyl-2-pyrrolidone, N,N-dimethyl Acetamide, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform; wherein the inner layer casting liquid includes a polymer polymer, a solvent and an auxiliary agent, wherein the polymer Polymers include but are not limited to polysulfone, polyethersulfone, polyphenylsulfone, polyamide, polyimide, polyamide-imide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polypropylene, Polycarbonate, polybenzimidazole, polyurethane; the solvent includes but not limited to n-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethylformyl Amine, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform; and the auxiliary agent includes but not limited to polyethylene glycol, ethylene glycol, glycerol, polyvinylpyrrolidone, water, ethanol, acetone, Lithium chloride, lithium bromide, calcium chloride; wherein the core liquid includes a solvent, a non-solvent and an auxiliary agent, wherein the auxiliary agent includes but not limited to polyethylene glycol, ethylene glycol, glycerol, polyvinylpyrrolidone, Water, ethanol, acetone, n-butanol.

3. The glycerol concentration method based on the hollow fiber pervaporation membrane according to claim 2, wherein the outer layer casting liquid is a mixed liquid of sulfonated polyphenylsulfone and n_methyl-2-pyrrolidone, The mass ratio of the sulfonated polyphenylsulfone is between 10-35%, the mass ratio of the n-methyl-2-P pyrrolidone is 65-90%, and the combined ratio of the two formulas is 100%; The inner layer casting liquid is: a mixture of polyphenylene stone, ethylene glycol and n_methyl-2-P pyrrolidone, wherein the mass ratio of the polyphenylene oxide is 10-30% , The mass ratio of the ethylene glycol is between 2-20%, the mass ratio of the n-methyl-2-pyrrolidone is 50-88%, and the combined ratio of the three formulas is 100%; the core The liquid is: n-methyl-2-pyrrolidone, water and ethylene glycol, wherein the mass ratio of the n-methyl-2-pyrrolidone is 50-99%, and the mass ratio of the water is 1-40%, The mass ratio of the ethylene glycol is 0-10%, and the combined ratio of the three formulas is 100%.

4. The glycerol concentration method based on hollow fiber pervaporation membrane according to claim 2, characterized in that the outer layer casting liquid: a mixed liquid of cellulose acetate and n_methyl-2-pyrrolidone, wherein The mass ratio of the cellulose acetate is between 1-25%, the mass ratio of the n_methyl-2-pyrrolidone is 75-99%, and the combined ratio of the two formulas is 100%; Inner layer casting liquid: a mixed liquid of polyetherimide, polyethylene glycol and n-methyl-2-pyrrolidone, wherein the mass ratio of the polyphenylsulfone is 10-30%, and the polyethylene glycol The mass ratio is between 1-10%, the mass ratio of the n-methyl-2-pyrrolidone is 60-89%, and the combined ratio of the three formulas is 100%; the core liquid: n-methyl- 2-pyrrolidone, water and polyethylene glycol, wherein the mass ratio of n_methyl-2-pyrrolidone is 50-99%, the mass ratio of the water is 1-40%, the mass ratio of the polyethylene glycol is 0-10%, and the combined ratio of the three formulas is 100%.

5. The glycerol concentration method based on a hollow fiber pervaporation membrane according to claim 1, wherein the ultrafiltration membrane is an inorganic ceramic membrane or an organic membrane, and the ultrafiltration membrane is selected from hollow fiber membranes, plate membranes , Single-channel tubular membrane or multi-channel tubular membrane, the pore size of the ultrafiltration membrane is 0.01-0. 2 microns, when the ultrafiltration membrane is a ceramic ultrafiltration membrane, the ceramic ultrafiltration membrane The pore size is 0.01-0. 1 micron; when the ultrafiltration membrane is an organic ultrafiltration membrane, the organic ultrafiltration membrane is a hollow fiber membrane with a pore size of 0.01-0. 05 microns.

6. The glycerol concentration method based on a hollow fiber pervaporation membrane according to claim 1, wherein the operating pressure during ultrafiltration is 0.1-5 bar _; the gauge pressure on the intercept side of the pervaporation component is 0-3 bar , The absolute pressure on the permeate side is 5-30 mbar.

7. The glycerol concentration method based on a hollow fiber pervaporation membrane according to claim 1, wherein the hollow fiber pervaporation membrane has an outer diameter of 0.8-1. 5mm and an inner diameter of 0.5- 1. 2mm, the wall thickness is 0.1-0. 2mm.

8. The glycerin concentration equipment based on the hollow fiber pervaporation membrane is characterized in that it includes:

The ultrafiltration unit (2), buffer tank (3), preheater (5), heater (6) and pervaporation membrane group (7) are connected in sequence, wherein the permeate side of the pervaporation membrane group (7) is connected to the vacuum Unit (14), and a second condenser (11) is provided between the vacuum unit (14) and the pervaporation membrane unit (7), and the second condenser (11) is connected to the permeate tank (12) ; Among them, the interception side of the pervaporation membrane group (7) is connected to the product tank (9), and a first condenser (8) is provided between the product tank (9) and the pervaporation membrane group (7);

The pervaporation module is composed of a hollow fiber pervaporation membrane, and the hollow fiber pervaporation membrane sequentially forms an inner support layer from the inside of the membrane to the outside of the membrane, a selective separation layer and an outer protective layer, wherein The selective separation layer is placed between the inner support layer and the outer protective layer, and the outer protective layer has hydrophilicity; the preparation process of the hollow fiber pervaporation membrane is as follows: Step 1: Preparation Layer casting liquid, outer layer casting liquid and core liquid, the inner layer casting liquid, the outer layer casting liquid and the core liquid form a hollow tubular liquid film through the spinneret; Step 2: the hollow After passing through the air gap, the tubular liquid membrane enters the coagulation bath and is coagulated by phase change to obtain hollow fiber membrane filaments; and Step 3: processing the hollow fiber membrane filaments to obtain a hollow fiber pervaporation membrane; wherein the outer layer casting liquid includes a hydrophilic membrane Aqueous polymers and solvents, wherein the hydrophilic polymers include but are not limited to sulfonated polysulfone, sulfonated polyphenylsulfone, sulfonated polyethersulfone, sulfonated polyamide and sulfonated polyimide, polyethylene Alcohol, polyoxyethylene, cellulose, cellulose acetate, hydrolyzed polyacrylonitrile, polyvinylpyrrolidone, chitosan, polyetheramine and polyethyleneimine; the solvent includes but is not limited to n-methyl-2 -Pyrrolidone, N,N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform; wherein the inner layer casting liquid includes polymer polymer and solvent And additives, wherein the polymer macromolecules include, but are not limited to, polysulfone, polyethersulfone, polyphenylsulfone, polyamide, polyimide, polyamide-imide, polyvinylidene fluoride, polytetrafluoroethylene Ethylene, polyacrylonitrile, polypropylene, polycarbonate, polybenzimidazole, polyurethane; the solvents include, but are not limited to, n-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethylformaldehyde Amide, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform; and the adjuvants include but are not limited to polyethylene glycol, ethylene glycol, glycerol, polyvinylpyrrolidone, water, ethanol, acetone, Lithium chloride, lithium bromide, calcium chloride; wherein the core liquid includes a solvent, a non-solvent and an auxiliary agent, wherein the auxiliary agent includes but not limited to polyethylene glycol, ethylene glycol, glycerol, polyvinylpyrrolidone, Water, ethanol, acetone, n-butanol.

9. A glycerin concentration equipment based on a hollow fiber pervaporation membrane, characterized in that it comprises: the ultrafiltration membrane is an inorganic ceramic membrane or an organic membrane, and the ultrafiltration membrane is selected from hollow fiber membranes, plate membranes, and single-channel tubular membranes. Membrane or multi-channel tubular membrane, the pore size of the ultrafiltration membrane is 0.01-0.2 microns. When the super When the filter membrane is a ceramic ultrafiltration membrane, the pore size of the ceramic ultrafiltration membrane is 0.01-0.1 micron; when the ultrafiltration membrane is an organic ultrafiltration membrane, the organic ultrafiltration membrane is a hollow fiber membrane with a pore size of 0.01-0.1 micron. 0.05 microns.

10. Glycerin concentration equipment based on hollow fiber pervaporation membrane, characterized in that it includes: a liquid tank (3), a heating device (15), a second transfer pump (4), a pervaporation membrane group (7), and a second Condenser (11), permeate tank (12) and vacuum unit (14); one side of the material tank (3) is connected to the heating device (15), and the other side of the material tank (3) is connected to the pervaporation membrane unit (7), wherein the permeate side of the pervaporation membrane unit (7) is connected to a vacuum unit (14), and a second condenser (14) is provided between the vacuum unit (14) and the pervaporation membrane unit (7) 11), the second condenser (11) is connected to the permeate tank (12); the intercept side of the pervaporation membrane group (7) is connected to the liquid tank (3), the liquid tank (3) and the pervaporation membrane group (7) A second transfer pump (4) is set between ), and the concentrated glycerol from the pervaporation membrane group (7) is sent back to the liquid tank (3); the pervaporation module is composed of hollow fiber pervaporation membranes, so The hollow fiber pervaporation membrane sequentially forms an inner support layer, a selective separation layer and an outer protective layer from the inside of the membrane to the outside of the membrane, wherein the selective separation layer is placed between the inner support layer and the outer protective layer Meanwhile, the outer protective layer is hydrophilic; the preparation process of the hollow fiber pervaporation membrane is as follows: Step 1: Prepare the inner layer casting liquid, the outer layer casting liquid and the core liquid, the inner layer casting film The liquid, the outer layer casting liquid and the core liquid pass through the spinneret to form a hollow tubular liquid film; Step 2: The hollow tubular liquid film enters the coagulation bath after passing through the air gap and is phase-change solidified to obtain a hollow fiber membrane yarn And step 3: processing the hollow fiber membrane filaments to obtain a hollow fiber pervaporation membrane; wherein the outer layer casting liquid includes a hydrophilic polymer and a solvent, wherein the hydrophilic polymer includes but is not limited to sulfonate Sulfonated polysulfone, sulfonated polyphenylsulfone, sulfonated polyethersulfone, sulfonated polyamide and sulfonated polyimide, polyvinyl alcohol, polyoxyethylene, cellulose, cellulose acetate, hydrolyzed polyacrylonitrile, Polyvinylpyrrolidone, chitosan, polyetheramine and polyethyleneimine; the solvent includes but not limited to n-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethylformamide, two Methyl sulfoxide, Tetrahydrofuran, dichloromethane, chloroform; wherein the inner layer casting liquid includes polymer polymers, solvents and additives, wherein the polymer polymers include, but are not limited to, polysulfone, polyethersulfone, and polyphenylsulfone , Polyamide, polyimide, polyamide-imide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polypropylene, polycarbonate, polybenzimidazole, polyurethane; the solvent includes but Not limited to n-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform; and the adjuvant includes but Not limited to polyethylene glycol, ethylene glycol, glycerol, polyvinylpyrrolidone, water, ethanol, acetone, lithium chloride, lithium bromide, and calcium chloride; wherein the core liquid includes solvents, non-solvents and additives, wherein The auxiliary agent includes but is not limited to polyethylene glycol, ethylene glycol, glycerol, polyvinylpyrrolidone, water, ethanol, acetone, and n-butanol.