Device for controlling membrane pollution through hot fluid and cleaning method

Abstract

The invention discloses a thermal fluid control membrane pollution device and a cleaning method, the thermal fluid control membrane pollution device comprises a fluid heater, the fluid heater is used for heating a fluid medium to 30-400 DEG C to form a gaseous thermal fluid flow, and the gaseous thermal fluid flow is conveyed to a membrane assembly through a communicating pipeline for thermal mass transfer; the membrane assembly is subjected to pollution suppression and cleaning treatment on attached pollutants through the thermal action, two input ports of the fluid heater are connected with the water supply pump and the gas storage tank through communicating pipelines respectively, the gas storage tank is connected with the gas supply pump, and no chemical cleaning agent needs to be added in the whole treatment and cleaning process. The membrane assembly is subjected to pollution inhibition or attached pollutants are cleaned through hot air or hot steam, residues of chemical agents, the follow-up treatment problem and the potential chemical corrosion risk to membrane materials are fundamentally avoided, and the membrane assembly is particularly suitable for the food and medicine industry with the extremely high cleanliness requirement.

Description

Technical Field

[0001] This invention relates to the field of membrane separation device technology, specifically to a thermal fluid control membrane fouling device and cleaning method. Background Technology

[0002] Membrane separation technology is widely used in water treatment, food processing, biomedicine and other fields. After use, the filter membrane adsorbs a large number of impurities inside and on its surface. Surface pollutants can be removed by conventional backwashing processes. However, organic pollutants often cause irreversible fouling of the membrane. Pollutants that cause irreversible fouling of the membrane usually include natural organic matter, microbial cells and their extracellular secretions adsorbed on the membrane pores or membrane surface.

[0003] In the prior art, Chinese Patent No. CN102101019A discloses a cleaning method for a membrane distillation module, which mainly uses traditional chemical cleaning to treat membrane fouling, including chemical cleaning at room temperature and high temperature; another example is Chinese Patent No. CN112604505A, which discloses a flat ceramic membrane cleaning device and its usage method, including a sludge scraping mechanism and a chemical backwashing mechanism, which mainly uses a combination of gas blowing and chemical rinsing to achieve the purpose of cleaning.

[0004] Based on the above information, the mainstream cleaning methods currently include chemical cleaning and physical cleaning. However, in actual use, chemical cleaning dissolves or degrades pollutants using chemical agents such as acids, alkalis, oxidants, or surfactants, but there is a risk of chemical residue, which may cause product contamination (such as in the food and pharmaceutical industries). Furthermore, long-term use can corrode membrane materials and system pipelines. Physical cleaning, on the other hand, mainly relies on hydraulic shear force (such as backwashing) or mechanical force (such as sponge ball scrubbing). Although there is no risk of chemical contamination, its effect on removing stubborn organic pollutants such as polymers and biofilms is limited. Moreover, the high-intensity physical action carries the risk of damaging the membrane surface (especially hollow fiber membranes), and its energy consumption is relatively high. Summary of the Invention

[0005] The purpose of this invention is to provide a thermal fluid control membrane fouling device and cleaning method to solve the problem of membrane assembly damage caused by traditional cleaning methods mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A thermal fluid control membrane fouling device includes a fluid heater that heats a fluid medium to 30°C to 400°C, forming a gaseous hot fluid flow that is transported to a membrane assembly via a connecting pipe for heat and mass transfer. The heat action inhibits fouling of the membrane assembly and cleans existing contaminants. The two inlets of the fluid heater are connected to a water supply pump and a gas storage tank via connecting pipes, respectively. The gas storage tank is connected to the air supply pump. The outlet of the fluid heater is connected to the membrane assembly via a connecting pipe and a thermal interface.

[0007] Preferably, a flow meter and a pressure gauge are installed in the connecting pipeline connected to the outlet of the fluid heater to monitor the flow rate and pressure of the fluid medium, respectively.

[0008] Preferably, the fluid medium is a dry gas, specifically air or nitrogen. In this case, cleaning the diaphragm assembly requires a low calorific value, and the water supply pump is turned off.

[0009] Preferably, the fluid medium is hot steam, which requires a high calorific value for cleaning the diaphragm assembly, so the water supply pump is turned on.

[0010] Preferably, the fluid heater has a built-in precision temperature control system for controlling the temperature, pressure, and flow rate of the fluid medium.

[0011] Preferably, the flow heater is an electric heater or a heat exchanger, and the precise temperature control system includes a temperature sensor, a PID temperature controller, and a fluid distribution device.

[0012] Preferably, the temperature of the fluid medium can be adjusted to 200℃-400℃, which does not exceed the thermal stability limit of the diaphragm component material.

[0013] A cleaning method for a thermal fluid-controlled membrane fouling device includes the following steps: S1. Parameter determination: Based on the heat resistance of the membrane assembly and the type of contaminants, determine the type and temperature of the fluid required for cleaning, and determine the temperature of the hot fluid. For biological contamination, the treatment temperature is 60℃ to 100℃, and for organic contamination, the treatment temperature is 100℃ to 150℃. When using a high-temperature resistant ceramic membrane, the treatment temperature can reach up to 400℃. S2, Heating Stage: Based on the fluid type determined in S1, set the corresponding temperature. When a lower temperature is required, only start the air supply pump to introduce air into the fluid heater at an initial temperature of 30°C to 50°C. Use the fluid heater to heat the air, and then raise the air temperature to the target processing temperature at a heating rate not exceeding 50°C / min. When a higher temperature is required, the air supply pump and water supply pump are turned on to introduce air and water into the fluid heater. The fluid heater heats the water and air to form hot steam. Then, the temperature of the hot steam is raised to the target processing temperature at a heating rate not exceeding 50°C / min. S3. Thermal cleaning execution stage: The fluid medium is supplied to the connecting pipeline through the flow meter, pressure gauge and fluid distribution device and sprayed out at the diaphragm assembly position. The fluid medium is used to backwash and clean the diaphragm assembly from the inside to the outside. The flow rate of the sprayed fluid medium is 0.5 m / s-2 m / s and the processing time is 10 min-60 min.

[0014] S4. Processing End Stage: After the preset processing time is reached, the system stops heating and can perform cooling and purging according to the program. Then the device enters a low-power standby state, waiting for the next cleaning command.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the thermal fluid control membrane fouling device and cleaning method adopt a novel structural design, the specific details of which are as follows: 1. The entire treatment and cleaning process requires no chemical cleaning agents. Hot air or steam is used to inhibit contamination of the membrane components or clean existing contaminants, fundamentally avoiding chemical residues, subsequent treatment problems, and potential chemical corrosion risks to membrane materials. It is especially suitable for the food and pharmaceutical industries, which have extremely high cleanliness requirements.

[0016] 2. It can use air, inert gas or specific steam as the heat medium, offering flexible selection. Through precise temperature and flow rate control, such as temperature control by fluid heaters and flow rate control by flow meters, it can be flexibly adapted to various membrane types, from high-temperature resistant ceramic membranes to temperature-sensitive polymer membranes (such as microfiltration, ultrafiltration, and nanofiltration membranes). Differentiated temperature strategies can be adopted for different pollutants (biological / organic / complex pollution) to achieve efficient targeted treatment.

[0017] 3. Compared with traditional hot water cleaning, using a controllable hot fluid (especially gas) as the medium usually consumes less energy, has a significant effect on the control and removal of biological and organic pollution, can effectively restore and maintain membrane flux (usually the recovery rate is >90%), and reduce operating pressure difference.

[0018] 4. For ceramic membranes, the innovative high-temperature (200-400℃) treatment mode provides an effective solution for stubborn organic pollutants such as oils and polymers that are difficult to treat by traditional methods, achieving deep removal of pollutants. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the cleaning device of the present invention; Figure 2This is a schematic diagram of the overall process of the cleaning method of the present invention; Figure 3 This is a schematic diagram of the low-temperature mode process of the present invention; Figure 4 This is a schematic diagram of the high-temperature mode process of the present invention.

[0020] In the diagram: 1. Fluid heater; 2. Water pump; 3. Air pump; 4. Air tank; 5. Connecting pipeline; 6. Flow meter; 7. Pressure gauge. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] A thermal fluid control membrane fouling device utilizes a fluid heater 1 to heat a fluid medium to 30°C to 400°C, forming a gaseous thermal fluid flow. This flow is then transported to a membrane assembly via a connecting pipe 5 for heat and mass transfer. The thermal action inhibits fouling of the membrane assembly and cleans any adhering contaminants. The two inlets of the fluid heater 1 are connected to a water supply pump 2 and a gas storage tank 4 via the connecting pipe 5, respectively. The gas storage tank 4 is connected to a gas supply pump 3. The outlet of the fluid heater 1 is connected to the membrane assembly via the connecting pipe 5 and a thermal interface.

[0023] A flow meter 6 and a pressure gauge 7 are installed in the connecting pipe 5 connected to the output port of the fluid heater 1 to monitor the flow rate and pressure of the fluid medium, respectively. When the fluid medium is a dry gas, specifically air or nitrogen, the diaphragm assembly requires a low calorific value, so the water supply pump 2 is turned off. When the fluid medium is hot steam, the diaphragm assembly requires a high calorific value, so the water supply pump 2 is turned on. The fluid heater 1 has a built-in precise temperature control system to control the temperature, pressure and flow rate of the fluid medium. The flow heater 1 is specifically an electric heater or a heat exchanger. The precise temperature control system includes a temperature sensor, a PID temperature controller and a fluid distribution device. The temperature of the fluid medium can be adjusted to 200℃-400℃, which does not exceed the thermal stability limit of the diaphragm assembly material.

[0024] A cleaning method for a thermal fluid-controlled membrane fouling device includes the following steps: S1. Based on the heat resistance of the membrane assembly and the type of contaminants, determine the type and temperature of the fluid required for cleaning, and determine the temperature of the hot fluid. For biological contamination, the treatment temperature is 60℃ to 100℃, and for organic contamination, the treatment temperature is 100℃ to 150℃. When using a high-temperature resistant ceramic membrane, the treatment temperature can reach up to 400℃. S2. Based on the fluid type determined in S1, set the corresponding temperature. When a lower temperature is required, only start the air supply pump 3 to introduce air into the fluid heater 1 at an initial temperature of 30°C to 50°C. Use the fluid heater 1 to heat the air, and then raise the air temperature to the target processing temperature at a heating rate not exceeding 50°C / min. When a higher temperature is required, the air supply pump 3 and the water supply pump 2 are turned on to introduce air and water into the fluid heater 1. The fluid heater 1 heats the water and air to form hot steam, and then the temperature of the hot steam is raised to the target processing temperature at a heating rate not exceeding 50°C / min. S3. The fluid medium is supplied to the connecting pipe 5 through the flow meter 6, pressure gauge 7 and fluid distribution device and sprayed out at the diaphragm assembly position. The fluid medium is used to backwash and clean the diaphragm assembly from the inside to the outside. The flow rate of the sprayed fluid medium is 0.5 m / s-2 m / s and the processing time is 10 min-60 min.

[0025] S4. After the preset processing time is reached, the system stops heating and can perform cooling and purging according to the program. Then the device enters a low-power standby state, waiting for the next cleaning command.

[0026] Example 1: Biofouling Control and Cleaning of Ultrafiltration Membranes in Municipal Wastewater Treatment Plants Application scenario: Flat-plate ultrafiltration membrane module in a membrane bioreactor (MBR) of a municipal wastewater treatment plant, used for periodic biofouling suppression and cleaning.

[0027] Membrane type and fouling: Alumina ceramic ultrafiltration membrane. The main challenge is biofouling from microbial metabolites (extracellular polymeric substances, EPS) and organic colloids.

[0028] Operation: Perform hot fluid maintenance once a week. Isolate the membrane module online. Start the device, introduce air and heat to 80°C. Introduce hot air into the membrane module channel at a flow rate of 1.2 m / s and continue treatment for 30 minutes. After treatment, briefly backwash the membrane module with low-pressure purified water.

[0029] Results: The membrane flux remains stable at over 92% of that of new membranes over a long period of time; the transmembrane pressure difference (TMP) increases slowly during system operation; and the chemical cleaning cycle is extended by more than 3 times.

[0030] Example 2: Cleaning of protein-grease contamination on filter membranes in food processing wastewater Application scenario: Treatment unit for concentrated wastewater from dairy processing, where membrane flux decreases after fouling.

[0031] Membrane type and fouling: Polyamide membrane. Fouling is mainly caused by protein denaturation and adsorption, and oil adhesion.

[0032] Operation: Online cleaning. The device generates hot air at 120°C, with a flow rate set to 1.8 m / s. The hot air flows through the concentration side of the membrane module and is processed for 45 minutes.

[0033] Results: After cleaning, the membrane permeate flux recovered to 90%. The removal rate of characteristic pollutants (as COD) in the wastewater recovered to 90%. FTIR analysis of the membrane surface showed a significant reduction in the characteristic peaks of proteins and lipids.

[0034] Example 3: Cleaning of stubborn tar-resin contaminants from ceramic microfiltration membranes in chemical plants Application scenario: Ceramic microfiltration system in the pretreatment stage of high-concentration organic wastewater in chemical plants, where the membrane is severely clogged.

[0035] Membrane type and fouling: Tubular alumina ceramic microfiltration membrane (pore size 0.2 μm). The membrane pores and surface were severely clogged by tar and resinous high-molecular-weight organic matter.

[0036] Procedure: High-temperature hot fluid cleaning is employed. Hot nitrogen gas (an inert gas to prevent oxidation) is heated from room temperature to 350°C at a rate of 50°C / min and kept stable. The treatment is carried out for 60 minutes at 350°C and a flow rate of 1.5 m / s.

[0037] Results: Membrane flux recovered to 92% of the initial flux. Thermogravimetric-mass spectrometry (TG-MS) analysis showed that most tar macromolecules underwent thermal decomposition. The total pollutant removal rate was approximately 89%.

[0038] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A thermal fluid control device for membrane fouling, characterized in that, include: The fluid heater (1) heats the fluid medium to 30°C to 400°C, forming a gaseous hot fluid flow, which is then transported to the diaphragm assembly through the connecting pipe (5) for heat and mass transfer. The heat action is used to suppress contamination of the diaphragm assembly and clean the contaminants that have been attached. The two inlets of the fluid heater (1) are connected to the water pump (2) and the gas storage tank (4) respectively through the connecting pipe (5). The gas storage tank (4) is connected to the air pump (3). The outlet of the fluid heater (1) is connected to the diaphragm assembly through the connecting pipe (5) and the thermal interface.

2. The thermal fluid control membrane fouling device according to claim 1, characterized in that: A flow meter (6) and a pressure gauge (7) are installed in the connecting pipe (5) connected to the output port of the fluid heater (1) to monitor the flow rate and pressure of the fluid medium, respectively.

3. The thermal fluid control membrane fouling device according to claim 2, characterized in that: The fluid medium is a dry gas, specifically air or nitrogen. At this time, cleaning the diaphragm assembly requires a low calorific value, so the water supply pump (2) is turned off.

4. The thermal fluid control membrane fouling device according to claim 2, characterized in that: The fluid medium is hot steam. At this time, cleaning the diaphragm assembly requires a high calorific value, so the water supply pump (2) is turned on.

5. The thermal fluid control membrane fouling device according to claim 1, characterized in that: The fluid heater (1) has a built-in precision temperature control system for controlling the temperature, pressure and flow rate of the fluid medium.

6. The thermal fluid control membrane fouling device according to claim 5, characterized in that: The flow heater (1) is specifically an electric heater or heat exchanger, and the precise temperature control system includes a temperature sensor, a PID temperature controller and a fluid distribution device.

7. The thermal fluid control membrane fouling device according to claim 1, characterized in that: The temperature of the fluid medium can be adjusted to 200℃-400℃, which does not exceed the thermal stability limit of the diaphragm component material.

8. A cleaning method for a thermal fluid controlled membrane fouling device, applicable to a thermal fluid controlled membrane fouling device as described in any one of claims 1-7, characterized in that: Includes the following steps: S1. Based on the heat resistance of the membrane assembly and the type of contaminants, determine the type and temperature of the fluid required for cleaning, and determine the temperature of the hot fluid. For biological contamination, the treatment temperature is 60℃ to 100℃, and for organic contamination, the treatment temperature is 100℃ to 150℃. When using a high-temperature resistant ceramic membrane, the treatment temperature can reach up to 400℃. S2. According to the fluid type determined in S1, set the corresponding temperature. When a lower temperature is required, only start the air supply pump (3) to introduce air into the fluid heater (1) at an initial temperature of 30°C to 50°C. Use the fluid heater (1) to heat the air, and then raise the air temperature to the target processing temperature at a heating rate of no more than 50°C / min. When a higher temperature is required, the air supply pump (3) and water supply pump (2) are turned on to introduce air and water into the fluid heater (1). The fluid heater (1) heats the water and air to form hot steam. Then, the temperature of the hot steam is raised to the target processing temperature at a heating rate not exceeding 50°C / min. S3. The fluid medium is supplied to the connecting pipeline (5) through the flow meter (6), pressure gauge (7) and fluid distribution device and sprayed out at the diaphragm assembly position. The fluid medium is used to backwash and clean the diaphragm assembly from the inside to the outside. The flow rate of the sprayed fluid medium is 0.5 m / s-2 m / s and the processing time is 10 min-60 min. S4. After the preset processing time is reached, the system stops heating and can perform cooling and purging according to the program. Then the device enters a low-power standby state, waiting for the next cleaning command.

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