Concentration device for reconstituted tobacco extraction liquid

Abstract

The utility model discloses a reconstituted tobacco extract concentration device which comprises a vacuum membrane distillation device and a ceramic membrane device, and the ceramic membrane device comprises a storage tank, a ceramic membrane assembly and a first water pump. The discharge port of the storage tank and the inlet end of the first water pump, the outlet end of the first water pump and the feed port of the ceramic membrane assembly, and the trapped fluid discharge port of the ceramic membrane assembly and the return port of the storage tank are respectively connected through a pipeline; the vacuum membrane distillation device comprises a vacuum membrane distillation assembly, the inlet end of the feeding side of the vacuum membrane distillation assembly is connected with the outlet end of a second water pump through a pipeline, the inlet end of the second water pump is connected with an outlet of a heating flask through a pipeline, and an inlet of the heating flask is connected with a permeate discharging port of a ceramic membrane assembly through a pipeline. A scavenging port in the condensation side of the vacuum membrane distillation assembly is connected with a scavenging pipeline. The device disclosed by the utility model has the advantages that the loss of heat-sensitive substances in the tobacco extract liquor is reduced while macromolecular impurities in the tobacco extract liquor are removed.

Description

Technical Field

[0001] This utility model relates to the technical field of reconstituted tobacco preparation apparatus using papermaking methods, and in particular to a concentration apparatus for reconstituted tobacco extract. Background Technology

[0002] Reconstituted tobacco, also known as tobacco sheet, is a type of tobacco produced by soaking, extracting, separating, concentrating, pulping, papermaking, flavoring, and drying waste materials from the entire cigarette production process. The resulting material closely resembles natural tobacco leaves. Reconstituted tobacco waste maximizes the utilization of raw materials, saves production costs, and the special treatments during the reconstitution process reduce harmful substances such as tar produced during combustion. For businesses, papermaking-based reconstituted tobacco production increases economic benefits, while for society, it offers significant environmental benefits.

[0003] Currently, there are three main methods for producing reconstituted tobacco: roll pressing, slurry pressing, and papermaking. Papermaking accounts for about three-quarters of the total reconstituted tobacco production. In the papermaking process, the refining and concentration of tobacco extract is a crucial and energy-intensive step, directly impacting product quality. The main factors affecting the quality of tobacco extract are the content of macromolecular impurities and aromatic substances. Traditional tobacco extract separation processes primarily use sieving and centrifugation, but these methods cannot effectively remove macromolecular proteins, starches, and other substances. Concentration processes use vacuum evaporation, but the high temperatures during concentration lead to the loss of aromatic substances in the extract. These issues affect the quality of domestically produced tobacco sheets. For major tobacco companies, achieving efficient separation and concentration of tobacco extract remains a key research focus.

[0004] Membrane separation technology is a highly efficient separation method based on the selective sieving effect of membrane materials to separate, purify, or concentrate different substances (such as molecules, ions, and particles). Its core principle is to utilize the differences in membrane pore size, chemical properties, or charge to cause different components in a mixture to pass through the membrane at different rates, thereby achieving separation. This technology features low energy consumption, high efficiency, simple operation, and minimal environmental pollution, and is widely used in water treatment, food and pharmaceuticals, chemicals, energy, and environmental protection.

[0005] Patent application CN101708063A discloses a method for concentrating extract in the production of tobacco sheets using a papermaking process. This method involves extracting tobacco stems and leaf fragments separately with water or ethanol solution, followed by solid-liquid separation to obtain the extract. The extract is then centrifuged and filtered, and the filtrate is concentrated using a reverse osmosis membrane. The concentrate is then further concentrated under vacuum or by spray drying. Patent application CN103349351A discloses a method for reconstituted tobacco using a papermaking process based on membrane separation technology. This method first purifies the crude extract of reconstituted tobacco using a ceramic microfiltration membrane, then further purifies it using an organic filter membrane, and finally concentrates it through nanofiltration or reverse osmosis and vacuum evaporation before coating. Patent application CN104305518A discloses a membrane extraction process for tobacco extract. This method involves soaking tobacco waste, including tobacco scraps and other tobacco waste from cigarette production, in water to obtain a tobacco soaking solution. The solution is then passed through a vibrating screen to separate solid impurities, yielding a tobacco extract. This extract is further processed through ultrafiltration, nanofiltration, evaporation, and reverse osmosis. While patent applications CN103349351A and CN104305518A effectively remove large-molecule proteins and starches from the tobacco extract, improving the quality of reconstituted tobacco, these methods suffer from low concentration efficiency, cumbersome processes, difficulty in cleaning membrane fouling, and loss of aromatic substances. In the patent application published with publication number CN101708063A, although the concentration method is simple and energy-efficient, the simple centrifugal filtration method cannot effectively remove large molecular proteins, starches and other substances in the tobacco extract, and the quality of the reconstituted tobacco leaves cannot be significantly improved. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a concentration device for reconstituted tobacco extract, which combines ceramic membrane pretreatment filtration with vacuum membrane distillation concentration, thereby removing large molecular impurities from the tobacco extract while reducing the loss of heat-sensitive substances in the tobacco extract.

[0007] This utility model is achieved through the following technical solution:

[0008] A concentration device for reconstituted tobacco extract includes a vacuum membrane distillation device and a ceramic membrane device. The ceramic membrane device includes a storage tank, a ceramic membrane module, and a first water pump. The outlet of the storage tank is connected to the inlet of the first water pump, the outlet of the first water pump is connected to the inlet of the ceramic membrane module, and the retentate outlet of the ceramic membrane module is connected to the return port of the storage tank via a first feed pipe, a second feed pipe, and a return pipe, respectively.

[0009] The vacuum membrane distillation apparatus includes a vacuum membrane distillation component. The inlet end of the feed side of the vacuum membrane distillation component is connected to the outlet end of a second water pump via a pipeline. The inlet end of the second water pump is connected to the outlet of a heating flask via a pipeline. The inlet of the heating flask is connected to the permeate outlet of a ceramic membrane component via a pipeline. The scavenging port on the condenser side of the vacuum membrane distillation component is connected to a gas source via a scavenging pipeline, and a scavenging valve is installed on the scavenging pipeline. The suction port on the condenser side of the vacuum membrane distillation component is connected to a vacuum pump via a suction pipeline, and a condenser is installed on the suction pipeline. A collection flask for collecting condensate is located below the condensate outlet of the condenser.

[0010] As a preferred embodiment of the above-mentioned apparatus, the vacuum membrane distillation apparatus further includes a constant temperature water bath, in which a heating flask is placed and heated by the constant temperature water bath.

[0011] As a preferred embodiment of the above-mentioned device, the storage tank is equipped with a thermometer for detecting the temperature of the liquid.

[0012] As a preferred embodiment of the above-mentioned device, a pressure gauge is provided on the second feeding pipe, and a reflux valve is provided on the reflux pipe.

[0013] As a preferred embodiment of the above-mentioned device, a negative pressure gauge is provided on a section of the suction pipe located on the inlet side of the condenser.

[0014] As a preferred embodiment of the above-mentioned device, the porous hydrophobic membrane of the vacuum membrane distillation component is a hydrophobic membrane or a hydrophobic and oleophobic membrane made of PTFE material, with a pore size of 0.2μm and a thickness of 230-250μm, and both have a non-woven fabric support layer.

[0015] As a preferred embodiment of the above-mentioned device, the contact angle of the porous hydrophobic membrane of the vacuum membrane distillation assembly is 130° to 140°.

[0016] As a preferred embodiment of the above-mentioned device, the ceramic membrane of the ceramic membrane assembly is made of alumina or silicon carbide, the pore size of the membrane is 10–100 nm, and the effective membrane area is 0.12 m². 2 .

[0017] As a preferred embodiment of the above-mentioned device, the vacuum degree on the condenser side of the vacuum membrane distillation assembly is 5-40 kPa, the temperature on the feed side is 50-70°C, and the flow rate on the feed side is 0.5-4 cm / s.

[0018] As a preferred embodiment of the above-mentioned apparatus, the heating flask is a three-necked round-bottom flask.

[0019] This invention has the following advantages over the prior art:

[0020] This invention provides a concentration device for reconstituted tobacco extract, which combines a vacuum membrane distillation device with a ceramic membrane device. This device removes large molecular impurities from the tobacco extract while reducing the loss of heat-sensitive substances. It not only effectively preserves the aroma components in the tobacco extract but also improves the quality and efficiency of reconstituted tobacco. Specific analysis is as follows:

[0021] Tobacco extracts typically contain a certain amount of particles and insoluble matter, which can cause some contamination and clogging of porous hydrophobic membranes. Ceramic membrane devices offer high filtration precision, effectively removing not only particles and insoluble matter from tobacco extracts but also large organic molecules such as proteins and starches. Pre-treatment filtration of the tobacco extract using a ceramic membrane device reduces membrane fouling in subsequent vacuum membrane distillation and improves the quality of reconstituted tobacco. Compared to traditional double-effect evaporation and concentration equipment, vacuum membrane distillation operates at lower temperatures, minimizing the loss of heat-sensitive substances in the tobacco extract and fully preserving its aroma components. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of this utility model.

[0023] Numbered in the diagram: 1. Storage tank; 2. Ceramic membrane module; 3. First water pump; 4. Thermometer; 5. Pressure gauge; 6. Reflux valve; 7. Vacuum membrane distillation module; 8. Second water pump; 9. Heating flask; 10. Constant temperature water bath; 11. Permeate outlet; 12. Scavenging pipeline; 13. Scavenging valve; 14. Vacuum pump; 15. Condenser; 16. Collection flask; 17. Negative pressure gauge; 18. Tail pipe. Detailed Implementation

[0024] The embodiments of this utility model are described in detail below. These embodiments are implemented based on the technical solution of this utility model and provide detailed implementation methods and specific operation processes. However, the protection scope of this utility model is not limited to the following embodiments.

[0025] See Figure 1 This embodiment discloses a concentration device for reconstituted tobacco extract, including a vacuum membrane distillation device and a ceramic membrane device.

[0026] The ceramic membrane device includes a storage tank 1, a ceramic membrane module 2, and a first water pump 3. The outlet of the storage tank 1 is connected to the inlet of the first water pump 3, the outlet of the first water pump 3 is connected to the inlet of the ceramic membrane module 2, and the retentate outlet of the ceramic membrane module 2 is connected to the return port of the storage tank 1 via a first feed pipe, a second feed pipe, and a first return pipe, respectively. A thermometer 4 for detecting the temperature of the feed liquid is installed on the storage tank 1. A pressure gauge 5 is installed on the second feed pipe, and a return valve 6 is installed on the first return pipe.

[0027] The ceramic membrane of ceramic membrane module 2 is made of alumina or silicon carbide, with a pore size of 10–100 nm and an effective membrane area of ​​0.12 m². 2 .

[0028] The vacuum membrane distillation apparatus includes a vacuum membrane distillation component 7. The inlet end of the feed side of the vacuum membrane distillation component 7 is connected to the outlet end of a second water pump 8 via a pipeline. The inlet end of the second water pump 8 is connected to the outlet of a heating flask 9 via a pipeline. The heating flask 9 is placed in a constant temperature water bath 10 and heated by the constant temperature water bath 10. The inlet of the heating flask 9 is connected to the permeate outlet 11 of the ceramic membrane component 2 via a pipeline. The scavenging port on the condenser side of the vacuum membrane distillation component 7 is connected to a gas source via a scavenging pipeline 12. A scavenging valve 13 is provided on the scavenging pipeline 12. The suction port on the condenser side of the vacuum membrane distillation component 7 is connected to a vacuum pump 14 via a suction pipeline. A condenser 15 is provided on the suction pipeline. The condenser 15 can be a serpentine condenser tube. A collection flask 16 for collecting condensate is provided below the condensate outlet of the condenser 15. The condensate outlet of the condenser 15 is connected to the collection flask 16 via a tail pipe 18. A negative pressure gauge 17 is installed on a section of the suction line located on the inlet side of the condenser 15.

[0029] The contact angle of the porous hydrophobic membrane in the vacuum membrane distillation assembly 7 is 130° to 140°. The porous hydrophobic membrane in the vacuum membrane distillation assembly 7 is made of PTFE material and is either a hydrophobic or hydrophobic oleophobic membrane with a pore size of 0.2 μm and a thickness of 230 to 250 μm. Both membranes have a non-woven fabric support layer.

[0030] The vacuum degree on the condenser side of the vacuum membrane distillation unit 7 is 5-40 kPa, the temperature on the feed side is 50-70℃, and the flow rate on the feed side is 0.5-4 cm / s.

[0031] The heating flask 9 is a three-necked round-bottom flask. The three necks of the three-necked round-bottom flask are used as the inlet, outlet and reflux port, respectively. The outlet end of the top of the feed side of the vacuum membrane distillation assembly 7 is connected to the reflux port at the top of the three-necked round-bottom flask through the second reflux pipe.

[0032] In this embodiment, a purging port is provided on the condensation side of the vacuum membrane distillation assembly 7, and a purging pipeline 12 with a purging valve 13 is connected to the purging port. This can provide a purging airflow to the condensation side of the vacuum membrane distillation assembly 7, thereby adjusting the vacuum level on the condensation side, increasing the permeation flux of the vacuum membrane distillation assembly 7, and alleviating the wetting phenomenon of the porous hydrophobic membrane during the distillation process of the vacuum membrane distillation assembly 7.

[0033] The working process of the reconstituted tobacco extract concentration device provided by this utility model is as follows:

[0034] (1) Pretreatment and heating of the feed liquid:

[0035] The first water pump 3 is started, and the tobacco extract in the storage tank 1 is pumped into the ceramic membrane module 2. The extract undergoes pretreatment filtration through the ceramic membrane module 2 to remove large molecular impurities. The pretreated tobacco extract then enters the heating flask 9 in the vacuum membrane distillation device through the permeate outlet 11 of the ceramic membrane module 2 for heating. The retentate from the ceramic membrane module 2 flows back to the storage tank 1 through the first reflux pipe.

[0036] (2) Feed circulation and water mass transfer:

[0037] The second water pump 8 is started, and the permeate of the heated tobacco extract is introduced into the feed side of the vacuum membrane distillation assembly 7 at a flow rate of 0.5–4 cm / s. A vacuum environment of 5–40 kPa is applied by the vacuum pump 14 connected to the condenser side of the vacuum membrane distillation assembly 7. Since the saturated vapor pressure of the solution on the porous hydrophobic membrane surface is higher than the pressure on the condenser side, a vapor pressure difference is formed on both sides of the membrane. Driven by the vapor pressure difference, the vapor on the surface of the porous hydrophobic membrane will pass through the porous hydrophobic membrane with a pore size of 0.2 μm and a thickness of 230–250 μm, while the solution is blocked by the porous hydrophobic membrane and flows back to the heating flask 9 through the second reflux pipe.

[0038] (3) Steam condensation and collection:

[0039] During operation, the scavenging valve 13 is kept open, and the scavenging airflow is blown to the condensing side through the scavenging port on the condensing side of the vacuum membrane distillation assembly 7 to regulate the vacuum level on the condensing side of the vacuum membrane distillation assembly 7. Driven by the scavenging airflow and the vapor pressure difference on both sides of the porous hydrophobic membrane, the vapor passing through the porous hydrophobic membrane is condensed by the condenser 15 and collected by the collection flask 16.

[0040] Example 1

[0041] The applicant used the aforementioned ceramic membrane device to pretreat tobacco extract to remove impurities such as macromolecular proteins and starch. 15L of tobacco extract was added to the storage tank 1 of the ceramic membrane device. The operating pressure of the ceramic membrane device was set to 0.3MPa. The experiment was stopped when the permeate volume reached 9L. The time required to filter out 1L was continuously measured. The pore size of the ceramic membrane was 10nm. In the permeate of the tobacco extract after passing through this ceramic membrane, the protein removal rate was 89.0%, the starch removal rate was 87.1%, and the total solids content was 5.8%. Figure 2 shows a graph of the flux of the ceramic membrane device in this embodiment as a function of operating time.

[0042]

[0043] As shown in Figure 2, the flux of the ceramic membrane device gradually decreases with increasing operating time. This is because a dense filter cake layer forms on the surface of the ceramic membrane during operation, which blocks the membrane pores and leads to a decrease in the permeate flux of the ceramic membrane device.

[0044] Example 2

[0045] The applicant used the aforementioned ceramic membrane device to pretreat tobacco extract to remove impurities such as macromolecular proteins and starch. This embodiment differs from Embodiment 1 only in the pore size of the ceramic membrane used. In this embodiment, a ceramic membrane with a pore size of 50 nm is used. In the permeate of the tobacco extract after passing through the ceramic membrane, the protein removal rate was 88.6%, the starch removal rate was 85.0%, and the total solids content was 5.9%. Figure 3 shows a graph illustrating the flux of the ceramic membrane device in this embodiment as a function of operating time.

[0046]

[0047] Example 3

[0048] The applicant used the aforementioned ceramic membrane device to pretreat tobacco extract, removing impurities such as macromolecular proteins and starch. This embodiment differs from Embodiment 1 only in the pore size of the ceramic membrane used. In this embodiment, a ceramic membrane with a pore size of 100 nm is used. In the permeate of the tobacco extract after passing through the ceramic membrane, the protein removal rate was 86.1%, the starch removal rate was 73.6%, and the total solids content was 6.0%. Figure 4 shows a graph illustrating the flux of the ceramic membrane device in this embodiment as a function of operating time.

[0049]

[0050] Example 4

[0051] The applicant used the aforementioned vacuum membrane distillation apparatus to concentrate the permeate from the tobacco extract after pretreatment with a ceramic membrane device (10 nm pore size). 200 mL of the tobacco extract permeate was added to the heated flask 9 in the vacuum membrane distillation apparatus. The flow rate on the feed side of the vacuum membrane distillation assembly 7 was controlled at 2 cm / s, and the feed side temperature was controlled at 70°C. Experiments were conducted using hydrophobic PTFE membranes and hydrophobic / oleophobic PTFE membranes, respectively. The vacuum level on the condenser side of the vacuum membrane distillation assembly 7 was set to 5–40 kPa. The permeate flux and organic matter rejection rate obtained by concentrating the tobacco extract permeate under different condenser side vacuum levels are shown in Table 1.

[0052] Table 1

[0053]

[0054] Table 1 shows that the permeate flux of the hydrophobic membrane is consistently higher than that of the hydrophobic-oleophobic membrane, due to the higher porosity and lower membrane resistance of the hydrophobic membrane. We can also see that the permeate flux increases with the increase of the vacuum level on the condenser side of the vacuum membrane distillation unit 7, because the increased vacuum level on the condenser side increases the driving force for vapor to cross the membrane. However, the increased vacuum level on the condenser side also increases the migration of low-boiling-point, volatile components, leading to an increase in the organic matter content in the condensate permeate. Table 1 also shows that the organic matter rejection rate of the hydrophobic membrane is consistently lower than that of the hydrophobic-oleophobic membrane, thanks to the higher hydrophobicity of the hydrophobic-oleophobic membrane. Furthermore, we can see that the organic matter rejection rate decreases with increasing condenser side vacuum level, indicating that a higher condenser side vacuum level increases the loss of organic matter.

[0055] Example 5

[0056] 200 mL of tobacco extract permeate pretreated with a ceramic membrane (10 nm pore size) was added to the heated flask 9 in the vacuum membrane distillation apparatus. The flow rate on the feed side of the vacuum membrane distillation unit 7 was controlled at 2 cm / s, and the vacuum on the condenser side was set to 10 kPa. Experiments were conducted using hydrophobic PTFE membranes and hydrophobic / oleophobic PTFE membranes, with the feed side temperature set between 50 and 65 °C. The permeate flux and organic matter rejection rate obtained by concentrating the tobacco extract permeate under different feed side temperatures are shown in Table 2.

[0057] Table 2

[0058]

[0059] Table 2 shows that the permeate flux of both hydrophobic and hydrophobic-oleophobic membranes gradually increases as the feed-side temperature increases from 50℃ to 65℃. This is because the boundary layer saturated vapor pressure has an exponential relationship with the temperature near the membrane surface; increasing the feed-side temperature leads to a sharp increase in the boundary layer saturated vapor pressure, resulting in a significant increase in permeate flux. Furthermore, we found that the organic matter content in the condensate increases with increasing feed-side temperature. This is because higher temperatures result in a higher relative partial pressure of organic matter in the boundary layer. We also observed that the organic matter rejection rate decreases with increasing feed-side temperature, as this leads to greater organic matter loss. Therefore, in practical applications, the feed-side temperature should be appropriately increased to improve the operating efficiency of the vacuum membrane distillation unit while maintaining permeate flux.

[0060] Example 6

[0061] 200 mL of tobacco extract permeate passing through a ceramic membrane device (10 nm pore size) was added to the heated flask 9 in the vacuum membrane distillation apparatus. The feed side temperature of the vacuum membrane distillation assembly 7 was controlled at 65 °C, and the vacuum degree on the condenser side was set to 10 kPa. Experiments were conducted using hydrophobic PTFE membranes and hydrophobic / oleophobic PTFE membranes, with feed side flow rates ranging from 0.5 to 4 cm / s. The permeate flux and organic matter rejection rate obtained by concentrating the tobacco extract permeate at different feed side flow rates are shown in Table 3.

[0062] Table 3

[0063]

[0064] Vacuum membrane distillation is a heat-driven membrane process. On the feed side, the evaporation of steam removes a significant amount of heat, resulting in a lower temperature of the feed solution closer to the boundary layer. Generally, higher permeate flux leads to more steam evaporating from the boundary layer, removing more heat and causing the membrane surface temperature to be lower than the actual feed temperature—a phenomenon known as temperature polarization. Table 3 shows that increasing the feed-side flow rate from 0.5 cm / s to 4 cm / s increases both the permeate flux and the organic matter content in the condensate. This is because increasing the feed flow rate enhances convection on the feed side, reducing the impact of temperature and concentration polarization on the performance of vacuum membrane distillation. Furthermore, increasing the feed flow rate also reduces membrane fouling caused by concentration polarization. Table 3 also shows that as the feed flow rate increases from 0.5 cm / s to 4 cm / s, the organic matter rejection rate decreases. The organic matter rejection rates of the hydrophobic and hydrophobic-oleophobic membranes decrease from 99.0% and 99.4% to 96.8% and 97.2%, respectively. Taking all factors into consideration, in order to reduce membrane fouling during subsequent repeated stabilization experiments, the feed-side flow rate can be appropriately increased in practical industrial applications.

[0065] Example 7

[0066] Add 500 mL of tobacco extract that has undergone one vacuum membrane distillation to the heated flask 9 in the vacuum membrane distillation apparatus. The organic matter concentration of the feed liquid is 212,500 mg / L. - 1. The feed-side temperature was controlled at 70℃, the condenser-side vacuum was set to 10kPa, and the feed-side flow rate was set to 4cm / s. To obtain a higher organic matter rejection rate, a hydrophobic and oleophobic membrane was used in the experiment. To verify the operational potential of the device, it was run continuously for 10 hours, and the final volume of the concentrated tobacco extract was 163mL, with an organic matter content of 613200mg L⁻¹. Through extreme concentration, the organic matter concentration was concentrated 2.9 times, and the organic matter rejection rate reached 94.1%. During the operation, the condenser permeate volume, permeation flux, and organic matter concentration of the condenser permeate were statistically analyzed or calculated every hour, as shown in Table 4.

[0067] Table 4

[0068]

[0069] As shown in Table 4, with the operation of the vacuum membrane distillation apparatus, the permeation flux decreased over time due to the increased fouling of the hydrophobic and oleophobic membrane surface during the process, starting from an initial 9.9 mL / m³. -2 h-1 decreased to 1.0 mL m -2 h-1. Due to the increase in feed liquid concentration, the concentration of volatile organic compounds in the boundary layer increases, leading to an increase in the concentration of organic compounds in the condensate permeate as the experiment progresses.

[0070] Example 8

[0071] The contaminated porous hydrophobic membrane was obtained under the following parameters: the feed-side temperature was controlled at 65℃, and the vacuum degree on the condensation side was set to 10 kPa; hydrophobic membranes made of PTFE and hydrophobic-oleophobic membranes made of PTFE were selected for experiments, and the feed-side flow rate was set to 4 cm / s. -1 To meet practical industrial application requirements, the fouled membrane was cleaned with water for 30 minutes, and the permeation flux of the cleaned hydrophobic membrane was measured to be 11.1 mL / m³. -2 h-1, with a contact angle of 99.5°, has a permeation flux of 12.4 mL for a clean hydrophobic membrane. -2 h-1, contact angle 131.9°. The permeation flux of the hydrophobic and oleophobic film after cleaning was measured to be 9.8 mL m. -2 h-1, with a contact angle of 103.2°, and a permeation flux of 10.6 mL for a clean hydrophobic and oleophobic film. -2 h-1 has a contact angle of 136.5°.

[0072] Example 9

[0073] The contaminated porous hydrophobic membrane was obtained under the following parameters: the feed-side temperature was controlled at 65℃, and the vacuum degree on the condensation side was set to 10 kPa; hydrophobic membranes made of PTFE and hydrophobic-oleophobic membranes made of PTFE were selected for experiments, and the feed-side flow rate was set to 4 cm / s. -1 To meet practical industrial application requirements, the fouled membrane was cleaned with 0.5% HCl for 30 minutes. The permeation flux of the cleaned hydrophobic membrane was measured to be 11.5 mL / m³. -2 h-1, with a contact angle of 117.4°, and a permeation flux of 12.4 mL for a clean hydrophobic membrane. -2 h-1, contact angle 131.9°; the permeation flux of the hydrophobic and oleophobic film after cleaning was measured to be 9.9 mL m -2 h-1, with a contact angle of 123.4°, and a permeation flux of 10.6 mL for a clean hydrophobic and oleophobic film. -2h-1 has a contact angle of 136.5°.

[0074] Example 10

[0075] The contaminated porous hydrophobic membrane was obtained under the following parameters: the feed-side temperature was controlled at 65℃, and the vacuum degree on the condensation side was set to 10 kPa; hydrophobic membranes made of PTFE and hydrophobic-oleophobic membranes made of PTFE were selected for experiments, and the feed-side flow rate was set to 4 cm / s. -1 To meet practical industrial application requirements, the fouled membrane was cleaned with 0.5% NaOH for 30 minutes. The permeation flux of the cleaned hydrophobic membrane was measured to be 11.9 mL / m³. -2 h-1, with a contact angle of 128.3°, and a permeation flux of 12.4 mL for a clean hydrophobic membrane. -2 h-1, contact angle 131.9°; the permeation flux of the hydrophobic and oleophobic film after cleaning was measured to be 10.4 mL m - 2 h-1, with a contact angle of 129.8°, and a permeation flux of 10.6 mL for a clean hydrophobic and oleophobic film. -2 h-1 has a contact angle of 136.5°.

[0076] Example 11

[0077] The contaminated porous hydrophobic membrane was obtained under the following parameters: the feed-side temperature was controlled at 65℃, and the vacuum degree on the condensation side was set to 10 kPa; hydrophobic membranes made of PTFE and hydrophobic-oleophobic membranes made of PTFE were selected for experiments, and the feed-side flow rate was set to 4 cm / s. -1 To meet practical industrial application requirements, the fouled membrane was cleaned sequentially with 0.5% HCl and 0.5% NaOH for 30 minutes each, for a total cleaning time of 60 minutes. The permeation flux of the hydrophobic membrane after cleaning was measured to be 12.1 mL / m³. -2 h-1, with a contact angle of 130.5°, and a permeation flux of 12.4 mL for a clean hydrophobic membrane. -2 h-1, contact angle 131.9°; the permeation flux of the hydrophobic and oleophobic film after cleaning was measured to be 9.6 mL m -2 h-1, with a contact angle of 132.4°, and a permeation flux of 10.6 mLm for a clean hydrophobic and oleophobic film. -2 h-1 has a contact angle of 136.5°.

[0078] Examples 8-11 show that the flux of the fouled membranes recovered after cleaning, with almost no significant difference in water flux after cleaning with 0.5% NaOH and 0.5% HCl. The longer cleaning time with 0.5% HCl + 0.5% NaOH resulted in a more thorough removal of fouling from the membrane surface, leading to the highest final flux and the highest contact angle after cleaning. This indicates that the hydrophobicity of the membrane was well restored after cleaning with 0.5% HCl + 0.5% NaOH. Furthermore, we found that the contact angles after cleaning with 0.5% NaOH and 0.5% HCl + 0.5% NaOH were similar. Although the cleaning effect of 0.5% HCl + 0.5% NaOH was better, the cleaning time and reagent usage increased. In conclusion, in practical industrial applications, if the membrane surface fouling is severe, the cleaning method of 0.5% HCl + 0.5% NaOH can be considered.

[0079] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A concentration apparatus for reconstituted tobacco extract, comprising a vacuum membrane distillation apparatus, characterized in that: It also includes a ceramic membrane device, which includes a storage tank, a ceramic membrane module, and a first water pump. The outlet of the storage tank is connected to the inlet of the first water pump, the outlet of the first water pump is connected to the feed port of the ceramic membrane module, and the retentate outlet of the ceramic membrane module is connected to the return port of the storage tank through a first feed pipe, a second feed pipe, and a return pipe, respectively. The vacuum membrane distillation apparatus includes a vacuum membrane distillation component. The inlet end of the feed side of the vacuum membrane distillation component is connected to the outlet end of a second water pump via a pipeline. The inlet end of the second water pump is connected to the outlet of a heating flask via a pipeline. The inlet of the heating flask is connected to the permeate outlet of a ceramic membrane component via a pipeline. The scavenging port on the condenser side of the vacuum membrane distillation component is connected to a gas source via a scavenging pipeline, and a scavenging valve is installed on the scavenging pipeline. The suction port on the condenser side of the vacuum membrane distillation component is connected to a vacuum pump via a suction pipeline, and a condenser is installed on the suction pipeline. A collection flask for collecting condensate is located below the condensate outlet of the condenser.

2. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The vacuum membrane distillation apparatus also includes a constant temperature water bath, in which a heating flask is placed and heated.

3. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The storage tank is equipped with a thermometer to detect the temperature of the liquid.

4. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The second feed pipe is equipped with a pressure gauge, and the return pipe is equipped with a return valve.

5. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: A negative pressure gauge is installed on a section of the intake pipe located on the condenser inlet side.

6. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The porous hydrophobic membrane of the vacuum membrane distillation assembly is made of PTFE material, and is either a hydrophobic membrane or a hydrophobic and oleophobic membrane with a pore size of 0.2 μm and a thickness of 230–250 μm. Both membranes have a non-woven fabric support layer.

7. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The contact angle of the porous hydrophobic membrane in the vacuum membrane distillation assembly is 130° to 140°.

8. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The ceramic membrane of the ceramic membrane assembly is made of alumina or silicon carbide, with a pore size of 10–100 nm and an effective membrane area of ​​0.12 m². 2 .

9. The concentration apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The vacuum membrane distillation assembly has a condenser side vacuum of 5–40 kPa, a feed side temperature of 50–70 °C, and a feed side flow rate of 0.5–4 cm / s.

10. The concentrating apparatus for reconstituted tobacco extract as described in claim 1, characterized in that: The heating flask is a three-necked round-bottom flask.

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