A whole membrane system for purifying and concentrating phosphoric acid waste liquor

Abstract

The utility model discloses a kind of phosphoric acid waste liquid purification concentration whole membrane systems, including sequentially arranged ultrafiltration system (1000), nanofiltration system (2000) and membrane distillation system (3000);The membrane distillation system (3000) includes the membrane distillation raw water tank (3100) being communicated with the nanofiltration water tank (2600) effluent of nanofiltration system (2000), the first heat exchanger (3200) being communicated with membrane distillation raw water tank (3100) effluent, the second heat exchanger (3300) being communicated with first heat exchanger (3200) effluent, the membrane distillation tank (3400) being communicated with second heat exchanger (3300) effluent, the condenser (3500) being communicated with first heat exchanger (3200) steam outlet, the cold water tower (3600) being circularly communicated with condenser (3500).The utility model can achieve the technical effect that freely add or reduce membrane component quantity reaches different concentration required.

Description

Technical Field

[0001] This utility model relates to the field of phosphoric acid waste liquid purification technology, and in particular to a full membrane system for purifying and concentrating phosphoric acid waste liquid. Background Technology

[0002] Phosphoric acid is a commonly used chemical in the production processes of various fields such as electronics, agriculture, and biopharmaceuticals, resulting in a large amount of phosphoric acid wastewater every year, containing many suspended solids and metal ion impurities. In recent years, with increasingly stringent environmental protection requirements, the resource recovery technology for phosphorus-containing wastewater has gradually attracted attention. This technology can not only reduce environmental pollution but also achieve effective resource recycling, possessing significant research value and broad application prospects.

[0003] For the treatment of phosphoric acid waste liquid, a variety of technical methods have been commonly used in the past. In terms of filtering solid suspended solids, some methods use traditional physical filtration equipment, such as filter screens, to perform preliminary filtration of the waste liquid and intercept larger solid impurities. For removing metal ion impurities, the common practice is to use chemical precipitation, which involves adding specific chemical agents to the waste liquid to cause the metal ions to precipitate and separate. In addition, ion exchange resins are used to remove metal ions by utilizing the adsorption characteristics of resins for different ions. Some processes also combine evaporation and concentration, which use heating to evaporate water and thus increase the concentration of phosphoric acid.

[0004] However, these existing technologies have obvious drawbacks: traditional physical filtration is difficult to completely remove tiny suspended solids, which limits the purity of the treated phosphoric acid; chemical precipitation produces a large amount of chemical sludge, which not only increases the difficulty and cost of subsequent treatment, but may also introduce new impurities; ion exchange resins require frequent regeneration, are complex to operate and costly; and the evaporation and concentration process consumes a lot of energy, which leads to a significant increase in the cost of recovering phosphoric acid.

[0005] A method for controlling phosphorus concentration in a biological wastewater treatment plant is disclosed in US Patent Publication No. US06241888B1. This method involves aerating wastewater in an activation tank in the presence of activated sludge, and adding phosphorus at a controlled concentration to influence the properties of the activated sludge. The method includes measuring the phosphorus concentration in the activated sludge to control the addition of phosphorus, and controlling the addition of phosphorus in such a way that the phosphorus concentration in the activated sludge is greater than or equal to a lower limit and less than or equal to an upper limit. The method according to this invention can optimize the discharge values ​​of biological wastewater treatment equipment and better comply with the discharge value limits for wastewater treatment equipment stipulated by the authorities than currently available methods. However, this method for controlling phosphorus concentration in biological wastewater treatment plants mainly relies on adding phosphorus to increase the phosphorus concentration and cannot purify the phosphorus content in the wastewater.

[0006] A nucleotide solution purification and concentration system based on spiral wound ultrafiltration and nanofiltration technology is disclosed in Chinese patent document CN212881404U. This system includes an ultrafiltration stock tank, an ultrafiltration feed pump, a first security filter, a first circulation pump, an ultrafiltration membrane, an organic matter tank, a first-stage nanofiltration stock tank, a first-stage nanofiltration feed pump, a second security filter, a second circulation pump, a first-stage nanofiltration membrane, a second-stage nanofiltration stock tank, a second-stage nanofiltration feed pump, a third security filter, a third circulation pump, a second-stage nanofiltration membrane, and a permeate filter. The system includes a liquid tank and a finished product tank. The outlet of the ultrafiltration raw liquid tank is connected to the inlet of the ultrafiltration feed pump via a conduit. The outlet of the ultrafiltration feed pump is connected to the inlet of the first security filter via a conduit. The outlet of the first security filter is connected to the inlet of the first circulation pump via a conduit. This system improves the nucleotide hydrolysis rate and product yield, and the separation process is relatively easy. It has certain application and promotion value. However, this nucleotide solution purification and concentration system based on spiral wound ultrafiltration and nanofiltration technology only uses nanofiltration technology for purification, resulting in a low upper limit for purification concentration.

[0007] A waste liquid recovery device for electrode foil is disclosed in Chinese patent document CN210885551U. This device includes: a raw liquid tank, a booster pump, a security filter, a high-pressure pump, a nanofiltration membrane tank, and a product water tank. The raw liquid tank is connected to the booster pump to pressurize the raw liquid flowing through it. The booster pump is connected to the security filter to filter the pressurized raw liquid. The security filter is connected to the high-pressure pump to process the filtered raw liquid. The high-pressure pump is connected to the nanofiltration membrane tank to perform reverse osmosis treatment on the processed raw liquid. The nanofiltration membrane tank is connected to the product water tank to allow a phosphoric acid solution conforming to a preset standard, produced after reverse osmosis treatment, to flow into the product water tank. This solution can recover the phosphoric acid solution in the waste liquid of electrode foil, making the phosphoric acid solution reusable and saving the cost of phosphoric acid reagents. In addition, the concentration of other impurities in the waste liquid increases and their volume decreases, saving treatment costs. However, the waste liquid recovery device of this electrode foil uses a single filtration method for waste liquid recovery, resulting in poor purification effect.

[0008] A membrane distillation system for concentrating desulfurization wastewater is disclosed in Chinese patent document CN204981458U. This membrane distillation system for concentrating desulfurization wastewater offers advantages such as simple structure, convenient installation and maintenance, safe operation, small footprint, low operating cost, and full utilization of low-temperature waste heat resources. The system includes a desulfurization wastewater storage tank, a sand filter, a security filter, an ultrafiltration membrane tank, an ultrafiltration permeate tank, a plate preheater, and a membrane distillation module connected in sequence. The permeate outlet of the membrane distillation module is connected to the membrane distillation permeate tank, the concentrate outlet of the membrane distillation module is connected to the membrane distillation concentrate tank, and the gas outlet of the membrane distillation module is connected to the atmosphere. However, the membrane module of this membrane distillation system for concentrating desulfurization wastewater is inconvenient to replace and clean.

[0009] To address the shortcomings of the existing technologies, providing a full-membrane system for purifying and concentrating phosphoric acid waste liquid is a problem worthy of further research. Utility Model Content

[0010] The purpose of this invention is to overcome the shortcomings of poor single-layer filtration and provide a full-membrane system for purifying and concentrating phosphoric acid waste liquid, which enables the addition or reduction of the number of membrane modules to achieve the desired concentration.

[0011] The objective of this utility model is achieved through the following technical solution:

[0012] A phosphoric acid waste liquid purification and concentration all-membrane system includes an ultrafiltration system, a nanofiltration system, and a membrane distillation system arranged sequentially. The ultrafiltration system includes an ultrafiltration raw water tank, an ultrafiltration booster pump connected to the outlet of the ultrafiltration raw water tank, an ultrafiltration filter connected to the outlet of the ultrafiltration booster pump, an ultrafiltration circulation pump connected to the outlet of the ultrafiltration filter, an ultrafiltration membrane tank connected to the outlet of the ultrafiltration circulation pump, and an ultrafiltration product water tank connected to the product water outlet of the ultrafiltration membrane tank. The outlet of the ultrafiltration product water tank is connected to the nanofiltration system, and the pure water outlet of the ultrafiltration membrane tank is connected to an external drainage tank. The ultrafiltration system removes suspended solid particles contained in the phosphoric acid waste liquid by adjusting the influent flow rate at room temperature and thereby reaching a certain pressure through the ultrafiltration membrane module.

[0013] The nanofiltration system includes a nanofiltration raw water tank connected to the outlet of the ultrafiltration permeate tank, a nanofiltration booster pump connected to the outlet of the nanofiltration raw water tank, a nanofiltration filter connected to the outlet of the nanofiltration booster pump, a nanofiltration high-pressure pump connected to the outlet of the nanofiltration filter, a nanofiltration membrane tank connected to the outlet of the nanofiltration high-pressure pump, and a nanofiltration permeate tank connected to the permeate outlet of the nanofiltration membrane tank. The outlet of the nanofiltration permeate tank is connected to a membrane distillation system, and the pure water outlet of the nanofiltration membrane tank is connected to an external drainage tank. The nanofiltration system removes polyvalent ions (such as aluminum ions, zinc ions, and iron ions) contained in phosphoric acid waste liquid by adjusting the influent flow rate at room temperature and thereby reaching a certain pressure through the nanofiltration membrane module.

[0014] The membrane distillation system includes a membrane distillation raw water tank connected to the outlet of the nanofiltration permeate tank, a first heat exchanger connected to the outlet of the membrane distillation raw water tank, a second heat exchanger connected to the outlet of the first heat exchanger, a membrane distillation tank connected to the outlet of the second heat exchanger, a condenser connected to the steam outlet of the first heat exchanger, and a cooling tower connected to the condenser in a circulating manner. The membrane distillation system adjusts the flow rate of the nanofiltration permeate to reach a certain pressure, heats the nanofiltration permeate to 85°C through the heat exchanger, and then passes it through the membrane system. The generated steam is condensed into condensate by the condenser and enters the condensate tank. Phosphoric acid is returned to the raw water tank.

[0015] Preferably, the membrane distillation tank includes a membrane distillation tank body, a steam inlet located on one side of the membrane distillation tank body, a steam outlet located on the other side of the membrane distillation tank body, a pure water outlet located at the top of the membrane distillation tank body, a product water inlet located on one side of the bottom of the membrane distillation tank body, a product water outlet located on the other side of the bottom of the membrane distillation tank body, a distillation assembly located inside the membrane distillation tank body, and a membrane cleaning assembly located at the top of the membrane distillation tank body, which together can improve the purification and concentration effect of phosphoric acid waste liquid.

[0016] Preferably, the distillation assembly includes several heating tubes fixedly connected inside the membrane distillation tank, a pump disposed at the bottom of the heating tubes, and a reflux tube disposed at the top of the heating tubes, which effectively achieves the concentration of phosphoric acid waste liquid and, together with the ultrafiltration and nanofiltration sections, achieves the purpose of purifying and concentrating phosphoric acid waste liquid.

[0017] Preferably, the bottom of each heating tube is connected to the extraction pump, the top of each heating tube is bent towards the center and connected, the lower end of each heating tube is connected to the reflux pipe, and the upper end of each heating tube is connected to the bottom of the pure water outlet. The connection between the upper end of the heating tube and the bottom of the pure water outlet facilitates the discharge of the separated pure water, which helps to improve the working efficiency and effect of the membrane distillation stage in the purification and concentration process of phosphoric acid waste liquid.

[0018] Preferably, the heating tubes are arranged in multiple rings inside the membrane distillation tank, and the minimum distance between the heating tubes is greater than one millimeter. By arranging the heating tubes so that the gaps between the heating tubes are S-shaped, the hot steam flows in an S-shape inside the membrane distillation tank, prolonging the flow time of the hot steam inside the membrane distillation tank, so that the hot steam can fully heat the heating tubes and the phosphoric acid solution inside, and improve the heat utilization rate of the hot steam.

[0019] Preferably, the heating tube is made of duplex stainless steel or nickel-based alloy, and the inner surface of the heating tube is coated with a corrosion-resistant coating. Applying a corrosion-resistant coating to the inside of the heating tube can protect the inner wall of the heating tube, reduce the damage to the inner wall of the heating tube by the phosphoric acid solution, and avoid the situation where the highly corrosive phosphoric acid solution after purification damages the heating tube.

[0020] Preferably, the heating tube has a rhomboid cross-sectional shape, and the corners of the heating tube are rounded.

[0021] Preferably, the distance between the bottom of the extraction pump and the bottom of the inner wall of the membrane distillation tank is less than five centimeters, which is beneficial to improving the efficiency and quality of phosphoric acid concentration.

[0022] Preferably, the membrane cleaning assembly includes a servo motor fixedly connected to one side of the top of the membrane distillation tank, and two steam filter membranes fixedly connected to the output end of the servo motor.

[0023] Preferably, the two steam filter membranes are located outside the steam outlet and the pure water outlet, respectively, so as to realize the replacement and automatic cleaning of the two steam filter membranes, extend the service life of the steam filter membranes, reduce the frequency of cleaning and replacing the steam filter membranes by staff, and reduce manpower input.

[0024] Preferably, the membrane cleaning assembly further includes a pure water discharge pipe disposed at the top of the pure water outlet and a steam discharge pipe disposed outside the steam outlet;

[0025] Preferably, the end of the pure water discharge pipe is connected to the external drainage tank, and the end of the steam discharge pipe is connected to the first heat exchanger, so as to make full use of the heat of the hot steam and then return the fully utilized hot steam to the condenser for condensation and recovery, thereby reducing the water consumption of the equipment.

[0026] Preferably, the gap shape between the pure water discharge pipe and the pure water outlet is adapted to the shape of the steam filter membrane, and the gap shape between the steam outlet and the steam discharge pipe is adapted to the shape of the steam filter membrane. After the steam filter membrane rotates, it can perfectly enter the gap between the two to complete the assembly, so that the steam filter membrane can maintain good sealing performance during the process of filtering steam or self-cleaning.

[0027] Preferably, the ends of the pure water discharge pipe, pure water outlet, steam outlet, and steam discharge pipe are all arc-shaped, and the interface of the steam filter membrane is arc-shaped. The arcs of the interfaces of the pure water discharge pipe, pure water outlet, steam outlet, steam discharge pipe, and steam filter membrane are all centered on the output shaft of the servo motor. During the rotation, the steam filter membrane can be connected to the pipe in a more fitting manner, avoiding obstruction or loose connection caused by the straight pipe to the rotation of the steam filter membrane.

[0028] Preferably, the condenser includes a condenser tank, a cooling water inlet at one end of the condenser tank, a steam recovery port at the top of the other end of the condenser tank, a condensate outlet at the bottom of the other end of the condenser tank, a cooling water outlet at the top of the condenser tank, a condensation assembly inside the condenser tank, and a support assembly at the bottom of the condenser tank. The support assembly facilitates the installation and movement of the condenser, and as a whole, ensures the smooth operation of the steam cooling to water stage in the membrane distillation section, which is conducive to the stable operation of the phosphoric acid waste liquid purification and concentration full membrane system.

[0029] Preferably, the condensation assembly includes several condensing tubes fixedly connected to the inside of the condenser tank, several baffles disposed on the outside of the condensing tubes, and a partition plate disposed at the end of the condensing tubes. The condensation assembly consisting of condensing tubes, baffles and partition plates in the condenser can effectively improve the condensation effect of steam and enhance the device's treatment capacity and efficiency for phosphoric acid waste liquid.

[0030] Preferably, all the condenser tubes are U-shaped, and the partition plate separates the space at both ends of the condenser tube, increasing the steam flow path and time, so that the steam and cooling water can fully contact each other and improve the condensation efficiency.

[0031] Preferably, the baffles are equidistantly distributed inside the condenser tank, and the top or bottom of the baffles are provided with openings. The openings are staggered on the baffles to increase the flow path of the cooling water in the condenser tank and improve the heat exchange efficiency of the condenser.

[0032] Preferably, the edges of the baffles are provided with arc-shaped plates to make the cooling water flow more smoothly during the baffle process and reduce the noise generated during the cooling water baffle process.

[0033] Preferably, the support assembly includes several support legs fixedly connected to the bottom of the condenser tank and movable wheels rotatably connected to both sides of the support legs. The support legs are isosceles trapezoids, which support the condenser and improve its stability.

[0034] Preferably, the bottom height of the support leg is higher than the bottom height of the moving wheel, and pull rods are provided on both sides of the condenser tank.

[0035] Preferably, the cooling water inlet and cooling water outlet are connected to the outlet and inlet of the cooling tower, respectively, and the steam recovery port is connected to the steam outlet of the first heat exchanger.

[0036] Preferably, the condensate outlet is connected to a condensate tank, the top gas phase space of the condensate tank is connected to a vacuum pump, and the bottom water phase space of the condensate tank is connected to a self-priming pump. The vacuum pump ensures a stable negative pressure environment in the system by evacuating non-condensable gases (such as air and volatile organic compounds) from the condensate tank, thereby lowering the boiling point and improving evaporation efficiency. The self-priming pump can efficiently discharge condensate under negative pressure through a special structure (such as a gas-liquid separation chamber), avoiding excessively high liquid levels in the tank that could affect the vacuum level. The flow rate of the self-priming pump in the membrane distillation system is higher than that of the inlet pump to facilitate timely discharge of condensate from the condensate tank.

[0037] Preferably, the cooling tower includes a cooling tower body, a cooling tower outlet located on one side of the bottom of the cooling tower body, a cooling tower air inlet located on the other side of the bottom of the cooling tower body, a spray assembly located on the upper half of the inner wall of the cooling tower body, a cooling assembly located on the lower half of the inner wall of the cooling tower body, and a heat dissipation assembly located on the top of the cooling tower body.

[0038] Preferably, the spray assembly includes an input pipe fixedly connected to the upper half of the inner wall of the cooling tower, a plurality of water distribution pipes fixedly connected to the input pipe, and a plurality of spiral spray pipes rotatably connected to the bottom of the water distribution pipes.

[0039] Preferably, the water supply pipe is connected to the condensate outlet, the water distribution pipes are all connected to the water supply pipe, the spiral nozzles are all connected to the water distribution pipes, and the spiral nozzles are provided with a plurality of water outlet holes.

[0040] Preferably, a number of drive motors are fixedly connected to the top of the water distribution pipe, and the output ends of the drive motors are fixedly connected to the top rotating shaft of the spiral nozzle. Water is sprayed by the rotating spiral nozzle to form a water curtain with a large coverage area, which improves the uniformity of condensate spraying, allows the water curtain to fully contact the cold air, improves the heat exchange efficiency between condensate and cold air, and accelerates the cooling efficiency of condensate.

[0041] Preferably, the cooling component includes a heat dissipation packing fixedly connected to the lower half of the inner wall of the cooling tower, and a jet pipe fixedly connected to the bottom of the heat dissipation packing. The jet pipe helps to evenly disperse the gas and enhance the heat exchange effect with the water, and further improves the cooling efficiency in conjunction with the heat dissipation packing.

[0042] Preferably, the jet pipe is a vortex-shaped pipe, one end of which is connected to the air inlet of the cooling tower. A fan is connected to the end of the air inlet of the cooling tower. Several air outlets are opened at the top of the jet pipe. The packing material disperses the water flow into a thin film or fine water droplets through its complex geometric structure (such as corrugated plate, honeycomb or grid design), which significantly increases the contact area between water and air, promotes heat exchange and evaporative heat dissipation, and the packing layer can slow down the water flow speed.

[0043] Preferably, the heat dissipation assembly includes exhaust pipes disposed on both sides of the top of the cooling tower body, a cooling fan disposed inside the exhaust pipes, and a water separator disposed inside the exhaust pipes.

[0044] Preferably, the drain pipes are bent to both sides, and the water separator is located at the end of the drain pipe. The water collected by the water separator flows back to the cooling tower. Bending the end of the drain pipe can reduce the amount of dust and debris entering the cooling tower from the drain pipe. The water separator reduces the loss of cooling water by physically intercepting and separating water droplets carried in the airflow, thereby improving the utilization rate of cooling water and reducing the water consumption of the equipment.

[0045] Preferably, a number of V-shaped plates are fixedly connected to the top of the inner wall of the cooling tower body. The height of the V-shaped plates gradually decreases from the middle to both ends. The V-shaped plates are evenly distributed inside the cooling tower body and are located above the spray assembly.

[0046] Preferably, the condensate from the membrane distillation system is returned to the ultrafiltration membrane raw water tank to dilute and adjust the concentration of the feed phosphoric acid, thus saving water consumption.

[0047] Preferably, the steam generated by the membrane distillation system exchanges heat with the nanofiltration permeate, preheating the nanofiltration permeate before it enters the membrane distillation system, while simultaneously reducing the temperature of the steam. This helps to improve the subsequent concentration efficiency and also saves energy consumption of the membrane distillation system by reducing the steam temperature.

[0048] Preferably, the membrane distillation system is arranged in two sections according to the concentration to be concentrated. The first section concentrates phosphoric acid to 60 percent, and the second section concentrates phosphoric acid to more than 60 percent, which can achieve more precise and efficient phosphoric acid concentration and meet the usage requirements of phosphoric acid of different concentrations.

[0049] Preferably, the ultrafiltration system, nanofiltration system, and membrane distillation system are all equipped with monitoring devices for various indicators such as flow rate, temperature, pressure, conductivity, and pH. These devices enable online monitoring of various parameters of the concentrated membrane system, timely feedback on system operation status, and ensure process stability.

[0050] Preferably, the ultrafiltration system and the nanofiltration system each have their own independent cleaning system.

[0051] Preferably, the ultrafiltration membrane box includes an ultrafiltration membrane box body, transmission screws rotatably connected to the four corners of the inner wall of the ultrafiltration membrane box body, a sealing mechanism threadedly connected to the transmission screws, a connecting rod opening and closing mechanism disposed at one end of the ultrafiltration membrane box body, and an ultrafiltration membrane disposed between the sealing mechanisms.

[0052] Preferably, the sealing mechanism includes several sealing plates slidably connected to the interior of the ultrafiltration membrane housing. The four corners of the sealing plates are threadedly connected to the transmission screw. The sealing plates are arranged in pairs, and the ultrafiltration membrane is disposed between the two sealing plates in the same group. The threads on the two sealing plates in the same group are opposite, which enables the rapid assembly and disassembly of the ultrafiltration membrane inside the ultrafiltration membrane housing and improves the sealing performance and stability of the ultrafiltration membrane assembly.

[0053] Preferably, the shape of the sealing plate is adapted to the cross-sectional shape of the inner wall of the ultrafiltration membrane housing, the coefficient of friction between the sealing plate and the inner wall of the ultrafiltration membrane housing is less than 0.5, and a sealing ring is provided at the contact position between the sealing plate and the ultrafiltration membrane, so that the sealing plate can smoothly slide inside the ultrafiltration membrane housing to clamp or release the ultrafiltration membrane.

[0054] Preferably, a telescopic sealing sleeve is fixedly connected between two adjacent sealing plates that are not in the same group. The cross-sectional shape of the telescopic sealing sleeve is adapted to the shape of the sealing plate. The telescopic stroke of the telescopic sealing sleeve is twice the sliding stroke of the sealing plate, so as to avoid the situation where phosphoric acid waste liquid accumulates in the gap between adjacent sealing plates without sufficient ultrafiltration treatment.

[0055] Preferably, the linkage opening and closing mechanism includes three sets of transmission linkages respectively connected to the transmission screw, a telescopic cylinder rotatably connected to one end of the ultrafiltration membrane housing, and a connecting rod disposed between the end of the transmission screw and the output end of the telescopic cylinder;

[0056] A set of transmission links consists of three transmission rods. The ends of the set of transmission links are rotatably connected to two transmission screws. The length of the longest transmission rod is equal to the distance between two adjacent transmission screws. The three transmission rods of the set of transmission links form an equilateral quadrilateral, enabling one telescopic cylinder to control the rotation of four transmission screws. In turn, one telescopic cylinder controls the opening and closing of all sealing components, achieving rapid assembly, clamping, and limiting of the ultrafiltration membrane.

[0057] Preferably, an ultrafiltration inlet pipe is provided at the bottom of the ultrafiltration membrane housing, and the water distribution pipes of the ultrafiltration inlet pipe are respectively located below each sealing mechanism. A filtrate collection pipe is provided on one side of the ultrafiltration housing, and the end of the filtrate collection pipe is respectively connected to each ultrafiltration membrane. An ultrafiltration outlet pipe is provided on the other side of the ultrafiltration membrane housing, and the ultrafiltration outlet pipe is connected to the ultrafiltration membrane housing.

[0058] A full-membrane purification and concentration method for phosphoric acid waste liquid includes the following steps:

[0059] Phosphoric acid waste liquid enters the ultrafiltration filter from the ultrafiltration raw water tank through the ultrafiltration booster pump. The ultrafiltration filter removes particulate matter and other impurities from the liquid and prevents them from entering the circulation pump and ultrafiltration membrane module.

[0060] After passing through the ultrafiltration filter, the water enters the ultrafiltration circulation pump. After being pressurized again by the ultrafiltration circulation pump, it enters the ultrafiltration membrane tank. Under high pressure, the permeate enters the ultrafiltration permeate tank through the permeate pipeline, while the concentrate carrying the filtered solid suspended matter is discharged to the external drainage tank.

[0061] Ultrafiltration permeate enters the nanofiltration raw water tank via a booster pump. The nanofiltration raw water then enters the nanofiltration membrane tank. The concentrate, carrying the filtered-out metal ions, is discharged to the external drainage tank. Permeate is transported from the nanofiltration permeate tank to the membrane distillation raw water tank.

[0062] The membrane distillation raw water tank delivers membrane distillation raw water, which is heated to 85°C by the first heat exchanger and the second heat exchanger in sequence. The heated membrane distillation raw water is then transported into the membrane distillation tank for membrane distillation treatment.

[0063] The water produced by membrane distillation is the concentrated phosphoric acid product, and the pure water produced by membrane distillation is returned to the membrane distillation raw water tank.

[0064] The steam discharged from the membrane distillation tank is condensed into water by a condenser and enters a condensate tank. The condenser is connected to a cooling tower, which provides circulating cold water to the condenser. This system is designed for the purification and concentration of phosphoric acid waste liquid. It is highly automated, occupies a small area, and allows for the addition or reduction of membrane modules to achieve different concentrations. Phosphoric acid at various concentrations has different applications. Real-time online data monitoring can promptly reflect the operating status of the entire system and ensure the stability of the process.

[0065] Preferably, the self-priming pump flow rate of the membrane distillation system is higher than the inlet water pump flow rate, so that the condensate in the condensate tank can be discharged in a timely manner.

[0066] Positive and beneficial effects:

[0067] 1. The ultrafiltration system removes suspended solids from phosphoric acid waste liquid by adjusting the influent flow rate to achieve a certain pressure at room temperature and passing the ultrafiltration membrane module. The nanofiltration system removes polyvalent ions (such as aluminum, zinc, and iron ions) from phosphoric acid waste liquid by adjusting the influent flow rate to achieve a certain pressure at room temperature and passing the nanofiltration membrane module. The membrane distillation system heats the nanofiltration permeate to 85°C through a heat exchanger after adjusting the flow rate to achieve a certain pressure. The permeate then passes through the membrane system, and the generated steam is condensed into condensate in the condensate tank. The phosphoric acid is returned to the raw water tank.

[0068] 2. A servo motor-driven steam filter membrane is installed at the top of the membrane distillation tank. The two steam filter membranes are located on the outside of the steam outlet and the pure water outlet, respectively. After a period of purification, the servo motor is started to rotate the two steam filter membranes to switch positions. The clean steam filter membrane is used for filtration and purification, while the steam filter membrane that has been used for filtration is replaced on the outside of the steam outlet for steam self-cleaning, realizing the replacement and automatic cleaning of the two steam filter membranes.

[0069] 3. The pure water discharge pipe feeds the pure water produced by the membrane distillation tank into the external drainage tank. After purification, the water is discharged into the external water body or recycled back to the water-using equipment for reuse, reducing the equipment's water consumption. The steam discharge pipe is connected to the first heat exchanger, using the heat of the hot steam to initially heat the phosphoric acid raw water, making full use of the heat of the hot steam. The fully utilized hot steam then flows back to the condenser for condensation and recovery, reducing the equipment's water consumption.

[0070] 4. A sealing plate controlled by a drive screw is installed inside the ultrafiltration membrane housing. After the ultrafiltration membrane is assembled into the housing, rotating the drive screw causes the two sealing plates in the same group to move towards each other through the threaded transmission between the drive screw and the sealing plate, clamping the ultrafiltration membrane. This limits the movement of the ultrafiltration membrane, improves the stability of the ultrafiltration membrane assembly, and enhances the sealing performance between the ultrafiltration membranes. When it is necessary to remove the ultrafiltration membrane, simply rotate the drive screw in the opposite direction to separate the two sealing plates in the same group. This enables rapid assembly and removal of the ultrafiltration membrane inside the housing, improving the sealing performance and stability of the ultrafiltration membrane assembly.

[0071] 5. It is highly automated and occupies a small area for purifying and concentrating phosphoric acid waste liquid. At the same time, the number of membrane modules can be freely added or reduced to achieve different concentrations. Phosphoric acid of various concentrations has different uses.

[0072] 6. Real-time online data monitoring can promptly reflect the operating status of the entire system, ensuring the stability of the process.

[0073] 7. Preheating the nanofiltration permeate before it enters the membrane distillation system and lowering the steam temperature helps improve subsequent concentration efficiency and saves energy in the membrane distillation system. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the structure of the ultrafiltration system and nanofiltration system of this utility model;

[0075] Figure 2 This is a schematic diagram of the membrane distillation system of this utility model;

[0076] Figure 3 This is a schematic diagram of the structure of the membrane distillation vessel of this utility model;

[0077] Figure 4 This is a front view cross-sectional structural diagram of the membrane distillation flask of this utility model;

[0078] Figure 5 This utility model Figure 4 Enlarged structural diagram at point A;

[0079] Figure 6 This utility model Figure 4 Enlarged structural diagram at point B;

[0080] Figure 7 This is a top view cross-sectional structural diagram of the membrane distillation vessel of this utility model;

[0081] Figure 8 This is a schematic diagram of the membrane distillation jar of this utility model in its disassembled state;

[0082] Figure 9 This utility model Figure 8 Enlarged structural diagram at point C;

[0083] Figure 10 This is a cross-sectional structural diagram of the membrane distillation jar of this utility model in a disassembled state;

[0084] Figure 11 This is a schematic diagram of the condenser of this utility model;

[0085] Figure 12 This is a cross-sectional structural diagram of the condenser of this utility model;

[0086] Figure 13 This utility model Figure 12 Enlarged structural diagram at point D;

[0087] Figure 14 This is a rear view structural diagram of the condenser of this utility model;

[0088] Figure 15 This utility model Figure 14 Enlarged structural diagram at point E;

[0089] Figure 16 This is a schematic diagram of the condenser assembly of this utility model;

[0090] Figure 17 This is a cross-sectional structural diagram of the condenser assembly of this utility model;

[0091] Figure 18 This utility model Figure 17 Enlarged structural diagram at point F;

[0092] Figure 19 This is a schematic diagram of the structure of the cooling tower of this utility model;

[0093] Figure 20 This is a front view cross-sectional structural diagram of the cooling tower of this utility model;

[0094] Figure 21 This utility model Figure 20 Enlarged structural diagram at point G;

[0095] Figure 22 This utility model Figure 20 Enlarged structural diagram at point H;

[0096] Figure 23 This is a side sectional view of the present invention.

[0097] Figure 24 This utility model Figure 23 Enlarged structural diagram at point I;

[0098] Figure 25 This is a schematic diagram of the structure of the ultrafiltration box of this utility model;

[0099] Figure 26 This utility model Figure 25 Enlarged structural diagram at point J;

[0100] Figure 27 This is a side view of the ultrafiltration box of this utility model.

[0101] Figure 28 This is a cross-sectional structural diagram of the ultrafiltration box of this utility model;

[0102] Figure 29 This utility model Figure 28 Enlarged structural diagram at point K;

[0103] Figure 30 This utility model Figure 28 Enlarged structural diagram at point L;

[0104] Figure 31 This is a schematic diagram of the sealing mechanism and the connecting rod opening and closing mechanism of this utility model;

[0105] Figure 32 This is a schematic diagram of the front cross-sectional structure of the sealing mechanism and the connecting rod opening and closing mechanism of this utility model;

[0106] Figure 33 This utility model Figure 32 Enlarged structural diagram at point M;

[0107] Figure 34 This is a central cross-sectional view of the sealing mechanism and the connecting rod opening and closing mechanism of this utility model.

[0108] Figure 35This is a schematic diagram of the ultrafiltration membrane separation state of this utility model;

[0109] Figure 36 This is a process flow diagram of the ultrafiltration system of this utility model;

[0110] Figure 37 This is a process flow diagram of the nanofiltration system of this utility model;

[0111] Figure 38 This is a process flow diagram of the membrane distillation system of this utility model.

[0112] In the diagram: 1000 - Ultrafiltration system, 1100 - Ultrafiltration raw water tank, 1200 - Ultrafiltration booster pump, 1300 - Ultrafiltration filter, 1400 - Ultrafiltration circulation pump, 1500 - Ultrafiltration membrane tank, 1501 - Ultrafiltration membrane housing, 1502 - Drive screw, 1503 - Ultrafiltration membrane, 1504 - Sealing plate, 1505 - Telescopic sealing sleeve, 1506 - Drive connecting rod, 1507 - Telescopic cylinder, 1508 - Connecting rod, 1509 - Ultrafiltration inlet water pipe, 1510 - Filtrate collection pipe, 1511 - Ultrafiltration outlet water pipe, 1600 - Ultrafiltration product water tank;

[0113] 2000 - Nanofiltration system, 2100 - Nanofiltration raw water tank, 2200 - Nanofiltration booster pump, 2300 - Nanofiltration filter, 2400 - Nanofiltration high-pressure pump, 2500 - Nanofiltration membrane tank, 2600 - Nanofiltration product water tank;

[0114] 3000 - Membrane distillation system, 3100 - Membrane distillation raw water tank, 3200 - First heat exchanger, 3300 - Second heat exchanger;

[0115] 3400-Membrane distillation tank, 3401-Membrane distillation tank body, 3402-Steam inlet, 3403-Steam outlet, 3404-Pure water outlet, 3405-Product water inlet, 3406-Product water outlet, 3407-Heating tube, 3408-Pump, 3409-Reflux tube, 3410-Servo motor, 3411-Steam filter membrane, 3412-Pure water outlet tube, 3413-Steam outlet tube;

[0116] 3500-Condenser, 3501-Condenser tank, 3502-Cooling water inlet, 3503-Steam recovery port, 3504-Condensate outlet, 3505-Cooling water outlet, 3506-Condensate tube, 3507-Baffle plate, 3508-Divider plate, 3509-Arc plate, 3510-Support leg, 3511-Moving wheel, 3512-Tie rod;

[0117] 3600-Cold water tower, 3601-Cold water tower body, 3602-Cold water tower outlet, 3603-Cold water tower air inlet, 3604-Input pipe, 3605-Water distribution pipe, 3606-Spiral nozzle, 3607-Drive motor, 3608-Heat dissipation packing, 3609-Air jet pipe, 3610-Exhaust pipe, 3611-Cooling fan, 3612-Water separator, 3613-V-shaped plate. Detailed Implementation

[0118] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0119] A phosphoric acid waste liquid purification and concentration all-membrane system includes an ultrafiltration system 1000, a nanofiltration system 2000, and a membrane distillation system 3000 arranged sequentially. The membrane distillation system 3000 includes a membrane distillation raw water tank 3100 connected to the outlet of the nanofiltration product water tank 2600 of the nanofiltration system 2000, a first heat exchanger 3200 connected to the outlet of the membrane distillation raw water tank 3100, a second heat exchanger 3300 connected to the outlet of the first heat exchanger 3200, a membrane distillation tank 3400 connected to the outlet of the second heat exchanger 3300, a condenser 3500 connected to the steam outlet of the first heat exchanger 3200, and a cooling tower 3600 circulatedly connected to the condenser 3500.

[0120] The membrane distillation tank 3400 includes a membrane distillation tank body 3401, a steam inlet 3402 disposed on one side of the membrane distillation tank body 3401, a steam outlet 3403 disposed on the other side of the membrane distillation tank body 3401, a pure water outlet 3404 disposed on the top of the membrane distillation tank body 3401, a product water inlet 3405 disposed on one side of the bottom of the membrane distillation tank body 3401, a product water outlet 3406 disposed on the other side of the bottom of the membrane distillation tank body 3401, a distillation assembly disposed inside the membrane distillation tank body 3401, and a membrane cleaning assembly disposed on the top of the membrane distillation tank body 3401.

[0121] The ultrafiltration system 1000 includes an ultrafiltration raw water tank 1100, an ultrafiltration booster pump 1200 connected to the outlet of the ultrafiltration raw water tank 1100, an ultrafiltration filter 1300 connected to the outlet of the ultrafiltration booster pump 1200, an ultrafiltration circulation pump 1400 connected to the outlet of the ultrafiltration filter 1300, an ultrafiltration membrane tank 1500 connected to the outlet of the ultrafiltration circulation pump 1400, and an ultrafiltration product water tank 1600 connected to the product water outlet of the ultrafiltration membrane tank 1500. The outlet of the ultrafiltration product water tank 1600 is connected to the nanofiltration system 2000, and the pure water outlet of the ultrafiltration membrane tank 1500 is connected to the external drainage tank.

[0122] The nanofiltration system 2000 includes a nanofiltration raw water tank 2100 connected to the outlet of the ultrafiltration product water tank 1600, a nanofiltration booster pump 2200 connected to the outlet of the nanofiltration raw water tank 2100, a nanofiltration filter 2300 connected to the outlet of the nanofiltration booster pump 2200, a nanofiltration high-pressure pump 2400 connected to the outlet of the nanofiltration filter 2300, a nanofiltration membrane tank 2500 connected to the outlet of the nanofiltration high-pressure pump 2400, and a nanofiltration product water tank 2600 connected to the product water outlet of the nanofiltration membrane tank 2500. The outlet of the nanofiltration product water tank 2600 is connected to the membrane distillation system 3000, and the pure water outlet of the nanofiltration membrane tank 2500 is connected to the external drainage tank.

[0123] The distillation assembly includes several heating tubes 3407 fixedly connected inside the membrane distillation tank 3400, a pump 3408 disposed at the bottom of the heating tubes 3407, and a reflux pipe 3409 disposed at the top of the heating tubes 3407. The membrane cleaning assembly includes a servo motor 3410 fixedly connected to one side of the top of the membrane distillation tank 3401, and two vapor filter membranes 3411 fixedly connected to the output end of the servo motor 3410.

[0124] The condenser 3500 includes a condenser tank 3501, a cooling water inlet 3502 located at one end of the condenser tank 3501, a steam recovery port 3503 located at the top of the other end of the condenser tank 3501, a condensate outlet 3504 located at the bottom of the other end of the condenser tank 3501, a cooling water outlet 3505 located at the top of the condenser tank 3501, a condensation assembly disposed inside the condenser tank 3501, and a support assembly disposed at the bottom of the condenser tank 3501. The condensation assembly includes a plurality of condenser tubes 3506 fixedly connected inside the condenser tank 3501, a plurality of baffles 3507 disposed outside the condenser tubes 3506, and a partition plate 3508 disposed at the end of the condenser tubes 3506.

[0125] The cooling tower 3600 includes a cooling tower body 3601, a cooling tower outlet 3602 located on one side of the bottom of the cooling tower body 3601, a cooling tower air inlet 3603 located on the other side of the bottom of the cooling tower body 3601, a spray assembly located on the upper half of the inner wall of the cooling tower body 3601, a cooling assembly located on the lower half of the inner wall of the cooling tower body 3601, and a heat dissipation assembly located on the top of the cooling tower body 3601. The spray assembly includes an input pipe 3604 fixedly connected to the upper half of the inner wall of the cooling tower body 3601, a plurality of water distribution pipes 3605 fixedly connected to the input pipe 3604, and a plurality of spiral spray pipes 3606 rotatably connected to the bottom of the water distribution pipes 3605. The heat dissipation assembly includes exhaust pipes 3610 disposed on both sides of the top of the cooling tower body 3601, a cooling fan 3611 disposed inside the exhaust pipes 3610, and a water separator 3612 disposed inside the exhaust pipes 3610.

[0126] Example 1

[0127] like Figures 1 to 38 As shown, a phosphoric acid waste liquid purification and concentration all-membrane system includes an ultrafiltration system 1000, a nanofiltration system 2000, and a membrane distillation system 3000 arranged sequentially. The ultrafiltration system 1000 includes an ultrafiltration raw water tank 1100, an ultrafiltration booster pump 1200 connected to the outlet of the ultrafiltration raw water tank 1100, an ultrafiltration filter 1300 connected to the outlet of the ultrafiltration booster pump 1200, and an ultrafiltration circulation pump 14 connected to the outlet of the ultrafiltration filter 1300. 00. An ultrafiltration membrane tank 1500 is connected to the outlet of the ultrafiltration circulation pump 1400, and an ultrafiltration product water tank 1600 is connected to the product water outlet of the ultrafiltration membrane tank 1500. The outlet of the ultrafiltration product water tank 1600 is connected to the nanofiltration system 2000, and the pure water outlet of the ultrafiltration membrane tank 1500 is connected to the external drainage tank. The ultrafiltration system removes suspended solid particles contained in phosphoric acid waste liquid by adjusting the influent flow rate at room temperature and thereby reaching a certain pressure through the ultrafiltration membrane module.

[0128] The nanofiltration system 2000 includes a nanofiltration raw water tank 2100 connected to the outlet of the ultrafiltration product water tank 1600, a nanofiltration booster pump 2200 connected to the outlet of the nanofiltration raw water tank 2100, a nanofiltration filter 2300 connected to the outlet of the nanofiltration booster pump 2200, a nanofiltration high-pressure pump 2400 connected to the outlet of the nanofiltration filter 2300, a nanofiltration membrane tank 2500 connected to the outlet of the nanofiltration high-pressure pump 2400, and a nanofiltration product water tank 2600 connected to the product water outlet of the nanofiltration membrane tank 2500. The outlet of the nanofiltration product water tank 2600 is connected to the membrane distillation system 3000, and the pure water outlet of the nanofiltration membrane tank 2500 is connected to the external drainage tank. The nanofiltration system removes polyvalent ions (such as aluminum ions, zinc ions, and iron ions) contained in phosphoric acid waste liquid by adjusting the influent flow rate at room temperature to achieve a certain pressure through the nanofiltration membrane module.

[0129] The membrane distillation system 3000 includes a membrane distillation raw water tank 3100 connected to the outlet of the nanofiltration permeate tank 2600, a first heat exchanger 3200 connected to the outlet of the membrane distillation raw water tank 3100, a second heat exchanger 3300 connected to the outlet of the first heat exchanger 3200, a membrane distillation tank 3400 connected to the outlet of the second heat exchanger 3300, a condenser 3500 connected to the steam outlet of the first heat exchanger 3200, and a cooling tower 3600 circulatedly connected to the condenser 3500. The membrane distillation system adjusts the flow rate of the nanofiltration permeate to reach a certain pressure, heats the nanofiltration permeate to 85°C through the heat exchanger, and then passes it through the membrane system. The generated steam is condensed into condensate by the condenser and enters the condensate tank. Phosphoric acid is returned to the raw water tank.

[0130] like Figures 36 to 38As shown, this utility model also discloses a full-membrane method for purifying and concentrating phosphoric acid waste liquid, applied to the aforementioned full-membrane system for purifying and concentrating phosphoric acid waste liquid. The method includes the following steps:

[0131] Step 1: Phosphoric acid waste liquid enters the ultrafiltration filter 1300 from the ultrafiltration raw water tank 1100 through the ultrafiltration booster pump 1200. The ultrafiltration filter 1300 removes particulate matter and other impurities from the liquid to prevent them from entering the circulation pump and ultrafiltration membrane module.

[0132] Step 2: After passing through the ultrafiltration filter 1300, the water enters the ultrafiltration circulation pump 1400. After being pressurized again by the ultrafiltration circulation pump 1400, it enters the ultrafiltration membrane tank 1500. Under high pressure, the product water enters the ultrafiltration product water tank 1600 through the product water pipeline, and the concentrate carrying the filtered solid suspended matter is discharged to the external drainage tank.

[0133] Step 3: Ultrafiltration permeate enters nanofiltration raw water tank 2100 through a booster pump. Nanofiltration raw water enters nanofiltration membrane tank 2500 from nanofiltration raw water tank 2100. Concentrate carrying the filtered metal ions is discharged to external drainage tank. Permeate is transported from nanofiltration permeate tank 2600 to membrane distillation raw water tank 3100.

[0134] Step 4: Membrane distillation raw water is transported from the membrane distillation raw water tank 3100 and heated to 85°C by the first heat exchanger 3200 and the second heat exchanger 3300. The heated membrane distillation raw water is then transported into the membrane distillation tank 3400 for membrane distillation treatment.

[0135] Step 5: The water produced by distillation in membrane distillation tank 3400 is the concentrated phosphoric acid product. The pure water produced in membrane distillation tank 3400 is returned to membrane distillation raw water tank 3100.

[0136] Step Six: The steam discharged from the membrane distillation tank 3400 is condensed into water by the condenser 3500 and enters the condensate tank. The condenser 3500 is connected to the cooling tower 3600, which provides circulating cold water to the condenser. This system is designed for purifying and concentrating phosphoric acid waste liquid. It has a high degree of automation, a small footprint, and allows for the addition or reduction of membrane modules to achieve different concentrations. Phosphoric acid at various concentrations has different applications. Real-time online data monitoring can promptly reflect the operating status of the entire system and ensure the stability of the process.

[0137] like Figure 38 As shown, the flow rate of the self-priming pump in the membrane distillation system is higher than that of the inlet pump, so that the condensate in the condensate tank can be discharged in a timely manner.

[0138] The implementation principle of this embodiment is as follows: the ultrafiltration system removes suspended solid particles contained in the phosphoric acid waste liquid by adjusting the influent flow rate at room temperature and thereby reaching a certain pressure through the ultrafiltration membrane module; the nanofiltration system removes polyvalent ions (such as aluminum ions, zinc ions, and iron ions) contained in the phosphoric acid waste liquid by adjusting the influent flow rate at room temperature and thereby reaching a certain pressure through the nanofiltration membrane module; the membrane distillation system heats the nanofiltration permeate to 85°C through a heat exchanger after adjusting the flow rate to a certain pressure, and then passes it through the membrane system. The generated steam is condensed into condensate by a condenser and enters the condensate tank, while the phosphoric acid is returned to the raw water tank.

[0139] Example 2

[0140] like Figures 3 to 10 As shown, the difference between this embodiment and the above embodiment is that the membrane distillation tank 3400 includes a membrane distillation tank body 3401, a steam inlet 3402 disposed on one side of the membrane distillation tank body 3401, a steam outlet 3403 disposed on the other side of the membrane distillation tank body 3401, a pure water outlet 3404 disposed on the top of the membrane distillation tank body 3401, a product water inlet 3405 disposed on one side of the bottom of the membrane distillation tank body 3401, a product water outlet 3406 disposed on the other side of the bottom of the membrane distillation tank body 3401, and a membrane distillation tank body 3400. The distillation components inside the membrane distillation tank 3401, and the membrane cleaning components located on top of the membrane distillation tank 3401, first purify the phosphoric acid waste liquid through ultrafiltration and nanofiltration systems, and then further concentrate it through the membrane distillation system. The membrane distillation tank is equipped with a steam inlet, a steam outlet, a pure water outlet, a product water inlet, and a product water outlet to facilitate the entry and exit of steam and product water into and out of the membrane distillation tank. The internal distillation components can perform phosphoric acid concentration operations, and the membrane cleaning components on top can clean the membrane inside the membrane distillation tank. Together, they can improve the purification and concentration effect of the phosphoric acid waste liquid.

[0141] like Figures 4 to 10 As shown, the distillation assembly includes several heating tubes 3407 fixedly connected inside the membrane distillation tank 3400, a pump 3408 disposed at the bottom of the heating tubes 3407, and a reflux pipe 3409 disposed at the top of the heating tubes 3407. The heating tubes, the pump, and the reflux pipe constitute the membrane distillation assembly, which can effectively concentrate phosphoric acid waste liquid. In conjunction with the ultrafiltration and nanofiltration sections, it can achieve the purpose of purifying and concentrating phosphoric acid waste liquid.

[0142] like Figures 4 to 7As shown, the bottom of each heating tube 3407 is connected to the extraction pump 3408, the top of each heating tube 3407 is bent towards the center and connected, the lower end of each heating tube 3407 is connected to the reflux pipe 3409, and the upper end of each heating tube 3407 is connected to the bottom of the pure water outlet 3404. By installing heating tubes 3407 with extraction pumps 3408 and reflux pipes 3409 inside the membrane distillation tank 3401, the extraction pump 3408 draws phosphoric acid solution from the membrane distillation tank 3401 into the heating tubes 3407, causing the phosphoric acid solution to flow continuously within the heating tubes 3407. The hot steam entering the membrane distillation tank 3401 purifies the phosphoric acid solution within the heating tubes 3407. Heating converts the liquid water in the phosphoric acid solution into water vapor, which is discharged from the pure water outlet 3404, thus achieving the purpose of distillation and purification. The purified phosphoric acid solution is then returned to the membrane distillation tank 3401 through the reflux pipe 3409 for further distillation and purification until the concentration of the phosphoric acid solution reaches the expected concentration target. The bottom of the heating tube is connected to the extraction pump to extract the liquid. The top of the heating tube is bent towards the center and connected to facilitate the concentrated flow of liquid. The lower end of the heating tube is connected to the reflux pipe to allow the liquid to return for further processing. The upper end of the heating tube is connected to the bottom of the pure water outlet to facilitate the discharge of the separated pure water. This helps to improve the working efficiency and effect of the membrane distillation process in the purification and concentration of phosphoric acid waste liquid.

[0143] like Figure 7 As shown, the heating tubes 3407 are arranged in multiple rings inside the membrane distillation tank 3401. The minimum distance between the heating tubes 3407 is greater than one millimeter. By arranging the heating tubes 3407 in a ring, the space inside the membrane distillation tank 3400 is fully utilized, allowing the hot steam to fully contact the heating tubes 3407 and fully heat the phosphoric acid solution, thereby improving the heat exchange efficiency. Limiting the minimum distance between the heating tubes 3407 allows the hot steam to pass through smoothly, improving the flowability of the hot steam and making the phosphoric acid waste solution flow more evenly around the heating tubes, enhancing the heating effect, improving the concentration efficiency, and avoiding problems such as local overheating or poor flow caused by too small a distance. This helps the device to concentrate phosphoric acid waste solution stably and efficiently.

[0144] Furthermore, by arranging the heating tubes 3407 in an S-shape, the hot steam flows in an S-shape within the membrane distillation tank 3401, extending the flow time of the hot steam within the membrane distillation tank 3401. This allows the hot steam to fully heat the heating tubes 3407 and the internal phosphoric acid solution, thereby improving the heat utilization rate of the hot steam.

[0145] The heating element 3407 is made of duplex stainless steel or nickel-based alloy. The inner surface of the heating element 3407 is coated with a corrosion-resistant coating. Duplex stainless steel is inexpensive, has high mechanical properties, is resistant to high pressure and corrosion, making it particularly suitable for moderately corrosive, high-salt wastewater. It also possesses good thermal conductivity, significantly improving the thermal conductivity of the heating element 3407. Nickel-based alloys are resistant to high temperatures and strong corrosion, maintaining stability in strong acid environments and extending service life. The corrosion-resistant coating inside the heating element 3407 protects its inner wall, reducing damage from phosphoric acid and preventing damage from the highly corrosive phosphoric acid solution after purification.

[0146] like Figure 7 As shown, the cross-sectional shape of the heating tube 3407 is rhomboid, and the corners of the heating tube 3407 are rounded. By setting the heating tube 3407 to a rhomboid shape, the contact surface between the heating tube 3407 and the external hot steam is increased, thereby improving the heating efficiency.

[0147] like Figures 4 to 5 As shown, the distance between the bottom of the extraction pump 3408 and the bottom of the inner wall of the membrane distillation tank 3401 is less than five centimeters, which allows the extraction pump to get closer to the bottom of the membrane distillation tank, extract liquid more efficiently, reduce the amount of liquid remaining at the bottom of the membrane distillation tank, and improve the efficiency and quality of phosphoric acid concentration.

[0148] like Figures 3 to 10 As shown, the membrane cleaning assembly includes a servo motor 3410 fixedly connected to one side of the top of the membrane distillation tank 3401, and two steam filter membranes 3411 fixedly connected to the output end of the servo motor 3410.

[0149] like Figures 3 to 10As shown, two steam filter membranes 3411 are located outside the steam outlet 3403 and the pure water outlet 3404, respectively. By installing a servo motor 3410 driving the steam filter membranes 3411 at the top of the membrane distillation tank 3401, and with the two steam filter membranes 3411 located outside the steam outlet 3403 and the pure water outlet 3404, the steam filter membrane 3411 outside the pure water outlet 3404 filters the steam generated by heating. When the steam passes through the steam filter membrane 3411, phosphoric acid is intercepted and purified. The steam filter membrane 3411 outside the steam outlet 3405 is... Heated steam continuously cleans the steam filter membrane 3411, achieving automatic cleaning. After a period of purification, the servo motor 3410 is activated to rotate the two steam filter membranes to switch positions. The clean steam filter membrane 3411 performs the filtration and purification work, while the steam filter membrane 3411 that has been filtering for a period of time is replaced by the steam outlet 3403 for steam self-cleaning. This achieves the replacement and automatic cleaning of the two steam filter membranes 3411, extends the service life of the steam filter membrane 3411, reduces the frequency of cleaning and replacing the steam filter membrane by staff, and reduces manpower input.

[0150] like Figures 3 to 10 As shown, the membrane cleaning assembly also includes a pure water discharge pipe 3412 disposed at the top of the pure water outlet 3404 and a steam discharge pipe 3413 disposed outside the steam outlet 3403.

[0151] The end of the pure water discharge pipe 3412 is connected to the external drainage tank, and the end of the steam discharge pipe 3413 is connected to the first heat exchanger 3200. The pure water produced by the membrane distillation tank is input into the external drainage tank through the pure water discharge pipe 3412, purified and discharged to the outside water body, or recycled and returned to the water-using equipment for reuse, reducing the water consumption of the equipment. The steam discharge pipe 3413 is connected to the first heat exchanger, and the heat of the hot steam is used to initially heat the phosphoric acid raw water, making full use of the heat of the hot steam. The fully utilized hot steam is then returned to the condenser for condensation and recovery, reducing the water consumption of the equipment.

[0152] like Figures 8 to 9 As shown, the gap shape between the pure water discharge pipe 3412 and the pure water outlet 3404 is adapted to the shape of the steam filter membrane 3411, and the gap shape between the steam outlet 3403 and the steam discharge pipe 3413 is adapted to the shape of the steam filter membrane 3411. By limiting the gap shape between the pure water discharge pipe 3412 and the pure water outlet 3404 and between the steam outlet 3403 and the steam discharge pipe 3413, the steam filter membrane 3411 can perfectly enter the gap between the two after rotation, completing the assembly, so that the steam filter membrane 3411 can maintain good sealing performance during the process of filtering steam or self-cleaning.

[0153] Furthermore, the ends of the steam filter membrane 3411 are all equipped with sealing gaskets to ensure good sealing when connected to the pipeline.

[0154] like Figures 8 to 9 As shown, the ends of the pure water discharge pipe 3412, pure water outlet 3404, steam outlet 3403, and steam discharge pipe 3413 are all arc-shaped, and the interface of the steam filter membrane 3411 is also arc-shaped. The arcs of the interfaces of the pure water discharge pipe 3412, pure water outlet 3404, steam outlet 3403, steam discharge pipe 3413, and steam filter membrane 3411 are all centered on the output shaft of the servo motor 3410. By setting the interfaces of the pure water discharge pipe 3412, pure water outlet 3404, steam outlet 3403, steam discharge pipe 3413, and steam filter membrane 3411 to be arc-shaped, the steam filter membrane 3411 can fit more closely with the pipe during rotation, avoiding obstruction or loose connection caused by the straight pipe to the rotation of the steam filter membrane 3411.

[0155] The implementation principle of this embodiment is as follows: the heated nanofiltration permeate is purified by membrane distillation in membrane distillation tank 3400. After a period of purification, the servo motor 3410 is started to rotate and replace the two steam filter membranes. The clean steam filter membrane 3411 performs the filtration and purification work, while the steam filter membrane 3411 that has been filtering for a period of time is replaced on the outside of the steam outlet 3403 for steam self-cleaning. This realizes the replacement and automatic cleaning of the two steam filter membranes 3411, extends the service life of the steam filter membrane 3411, reduces the frequency of cleaning and replacing the steam filter membranes, and reduces manpower input.

[0156] Example 3

[0157] like Figures 11 to 18 As shown, the difference between this embodiment and the above embodiment is that the condenser 3500 includes a condenser tank 3501, a cooling water inlet 3502 opened at one end of the condenser tank 3501, a steam recovery port 3503 opened at the top of the other end of the condenser tank 3501, a condensate outlet 3504 opened at the bottom of the other end of the condenser tank 3501, a cooling water outlet 3505 opened at the top of the condenser tank 3501, a condensation component disposed inside the condenser tank 3501, and a support component disposed at the bottom of the condenser tank 3501. The specific structural design of the condenser enables it to receive steam from the first heat exchanger and cooling water from the cooling tower. The condensation component is used to achieve effective condensation of steam, and the condensate is discharged from the condensate outlet. The support component facilitates the installation and movement of the condenser. Overall, it ensures the smooth operation of the steam cooling to water stage of the membrane distillation section and helps the stable operation of the full membrane system for purifying and concentrating phosphoric acid waste liquid.

[0158] like Figures 12 to 18 As shown, the condensation assembly includes several condenser tubes 3506 fixedly connected inside the condenser tank 3501, several baffles 3507 disposed on the outside of the condenser tubes 3506, and a partition plate 3508 disposed at the end of the condenser tubes 3506. The condensation assembly consisting of condenser tubes, baffles and partition plates in the condenser can effectively improve the condensation effect of steam and enhance the treatment capacity and efficiency of the device for phosphoric acid waste liquid.

[0159] like Figures 16 to 18 As shown, all condenser tubes 3506 are U-shaped. The partition plate 3508 separates the space at both ends of the condenser tube 3506. By setting the partition plate 3508 at the end of the condenser tank 3501, the space at one end of the condenser tank 3501 is separated, so that after the steam enters from the steam recovery port 3503, it enters the condenser tube 3506 under the obstruction and guidance of the partition plate 3508. In the condenser tube 3506, it exchanges heat with the cooling water entering from the cooling water inlet 3502, so that the steam condenses into liquid and is discharged from the condensate outlet 3504, thus completing the condensation treatment of the recovered steam. This increases the steam flow path and time, allows the steam to fully contact the cooling water, and improves the condensation efficiency.

[0160] like Figures 16 to 18 As shown, baffles 3507 are equidistantly distributed inside the condenser tank 3501. The top or bottom of the baffles 3507 are provided with openings, which are staggered on the baffles 3507. By setting baffles 3507 inside the condenser tank 3501, the cooling water entering the condenser tank 3501 is deflected and guided, increasing the flow path of the cooling water in the condenser tank 3501, thereby enabling the cooling water to fully exchange heat with the steam and improving the heat exchange efficiency of the condenser.

[0161] like Figures 16 to 18 As shown, arc-shaped plates 3509 are provided at the edges of the baffle 3507. By providing arc-shaped plates 3509 at the edges of the baffle 3507, the cooling water flows more smoothly during the deflection process, reducing the noise generated during the deflection process and reducing the kinetic energy consumption of the cooling water flow process, thereby reducing the energy consumption of the cooling water delivery pump.

[0162] like Figures 11 to 15 As shown, the support assembly includes several support legs 3510 fixedly connected to the bottom of the condenser tank 3501, and movable wheels 3511 rotatably connected to both sides of the support legs 3510. The support legs 3510 are isosceles trapezoids. By setting the support legs 3510 at the bottom of the condenser tank 3501, the condenser is supported, thereby improving the stability of the condenser.

[0163] like Figures 14 to 15As shown, the bottom height of the support leg 3510 is higher than the bottom height of the moving wheel 3511. Both sides of the condenser tank 3501 are equipped with pull rods 3512. By setting the moving wheel 3511 on both sides of the support leg 3510, when the condenser needs to be moved, it can be tilted at a certain angle so that the moving wheel 3511 contacts the ground, which can convert sliding friction into rolling friction, making the movement of the condenser more labor-saving and efficient. The pull rods 3512 on both sides of the condenser tank 3501 facilitate the pulling of the tank for movement.

[0164] The cooling water inlet 3502 and cooling water outlet 3505 are connected to the outlet and inlet of the cooling tower 3600, respectively. The steam recovery port 3503 is connected to the steam outlet of the first heat exchanger 3200, so as to realize the recycling of cooling water, improve the water resource utilization rate, and enable the steam to effectively enter the condenser from the first heat exchanger for condensation, ensuring the normal operation of the device and realizing the purification and concentration treatment of phosphoric acid waste liquid.

[0165] The condensate outlet 3504 is connected to a condensate tank. A vacuum pump is connected to the top gas phase space of the condensate tank, and a self-priming pump is connected to the bottom water phase space of the condensate tank. The condensate at the condenser outlet may be discharged intermittently due to flow fluctuations or pressure changes. The condensate tank acts as a buffer container to avoid direct discharge that could cause system pressure fluctuations. The vacuum pump maintains the system's vacuum level. In membrane distillation or vacuum concentration processes, the vacuum pump ensures a stable negative pressure environment within the system by drawing non-condensable gases (such as air and volatile organic compounds) from the condensate tank, thereby lowering the boiling point and improving evaporation efficiency. The self-priming pump, through a special structure (such as a gas-liquid separation chamber), can efficiently discharge condensate under negative pressure, preventing the liquid level in the tank from being too high and affecting the vacuum level. The flow rate of the self-priming pump in the membrane distillation system is higher than that of the inlet pump to facilitate timely discharge of condensate from the condensate tank.

[0166] The implementation principle of this embodiment is as follows: Cooling water enters from the cooling water inlet 3502, passes through the openings of multiple baffles 3507, and exits from the cooling water outlet 3505. Under the action of the baffles 3407, the cooling water flows in an S-shape. Steam enters from the steam recovery port 3503, passes through the condenser tube 3506, and exits from the condensate outlet 3504. The U-shaped condenser tube 3506 causes the internal steam to move back and forth, thereby increasing the heat exchange time between the cooling water and the steam, and fully exchanging heat to make the steam condense into condensate. The arc-shaped plate 3509 on the baffle 3407 guides the flow of cooling water and improves the smoothness of the cooling water flow.

[0167] Example 4

[0168] like Figures 19 to 24As shown, the difference between this embodiment and the above embodiment is that the cooling tower 3600 includes a cooling tower body 3601, a cooling tower outlet 3602 disposed on one side of the bottom of the cooling tower body 3601, a cooling tower air inlet 3603 disposed on the other side of the bottom of the cooling tower body 3601, a spray assembly disposed on the upper half of the inner wall of the cooling tower body 3601, a cooling assembly disposed on the lower half of the inner wall of the cooling tower body 3601, and a heat dissipation assembly disposed on the top of the cooling tower body 3601. The spray assembly, cooling assembly and heat dissipation assembly work together to effectively reduce the water temperature, provide low-temperature cooling water for the condenser, ensure the condensation effect of the condenser, and thus ensure the stable operation of the entire membrane system for the purification and concentration process of phosphoric acid waste liquid.

[0169] like Figures 20 to 24 As shown, the spray assembly includes an input pipe 3604 fixedly connected to the upper half of the inner wall of the cooling tower body 3601, a plurality of water distribution pipes 3605 fixedly connected to the input pipe 3604, and a plurality of spiral spray pipes 3606 rotatably connected to the bottom of the water distribution pipes 3605.

[0170] like Figures 20 to 24 As shown, the water supply pipe 3604 is connected to the condensate outlet 3504, the water distribution pipes 3605 are all connected to the water supply pipe 3604, the spiral nozzles 3606 are all connected to the water distribution pipes 3605, and several water outlet holes are opened on the spiral nozzles 3606.

[0171] Several drive motors 3607 are fixedly connected to the top of the water distribution pipe 3605. The output ends of the drive motors 3607 are fixedly connected to the top rotating shaft of the spiral nozzle 3606. By setting the spiral nozzle 3606 driven by the drive motors 3607 on the water distribution pipe 3605, water is sprayed by the rotating spiral nozzle 3606 to form a water curtain with a large coverage area, which improves the uniformity of condensate spraying, allows the water curtain to fully contact the cold air, improves the heat exchange efficiency between condensate and cold air, and accelerates the cooling efficiency of condensate.

[0172] like Figures 20 to 22 As shown, the cooling component includes a heat dissipation packing 3608 fixedly connected to the lower half of the inner wall of the cooling tower body 3601, and a jet pipe 3609 fixedly connected below the heat dissipation packing 3608. The cooling component composed of the heat dissipation packing and the jet pipe can effectively cool the water in the cooling tower. The jet pipe helps to evenly disperse the gas and enhance the heat exchange effect with the water. Together with the heat dissipation packing, it further improves the cooling efficiency.

[0173] like Figures 10 to 23As shown, the jet pipe 3609 is a vortex-shaped pipe. One end of the jet pipe 3609 is connected to the air inlet 3603 of the cooling tower. A fan is connected to the end of the air inlet 3603 of the cooling tower. Several air outlets are opened at the top of the jet pipe 3609. By setting heat dissipation packing 3608 inside the cooling tower 3600, the heat dissipation packing is the core carrier of heat exchange. By increasing the contact area and extending the contact time, the cooling efficiency is improved. The packing disperses the water flow into a thin film or fine water droplets through its complex geometric structure (such as corrugated plate, honeycomb or grid design), which significantly increases the contact area between water and air, promotes heat exchange and evaporative heat dissipation, and the packing layer can slow down the water flow speed, extend the contact time between water and air, and improve the cooling efficiency. The vortex-shaped jet pipe 3609 pressurizes the external air and pushes it upward, forcing it through the packing layer, which enhances the air velocity and flow rate.

[0174] like Figures 20 to 22 As shown, the heat dissipation assembly includes exhaust pipes 3610 disposed on both sides of the top of the cooling tower body 3601, a cooling fan 3611 disposed inside the exhaust pipes 3610, and a water separator 3612 disposed inside the exhaust pipes 3610.

[0175] like Figures 19 to 23 As shown, the drain pipe 3610 bends to both sides, and the water separator 3612 is located at the end of the drain pipe 3610. The water collected by the water separator 3612 flows back to the cooling tower body 3601. Bending the end of the drain pipe 3610 can reduce the amount of dust and debris entering the cooling tower body 3601 from the drain pipe 3610. The water separator reduces the loss of cooling water by physically intercepting and separating water droplets entrained in the airflow, thereby improving the utilization rate of cooling water and reducing the water consumption of the equipment.

[0176] like Figure 24 As shown, several V-shaped plates 3613 are fixedly connected to the top of the inner wall of the cooling tower body 3601. The height of the V-shaped plates 3613 gradually decreases from the middle to both ends. The V-shaped plates 3613 are evenly distributed inside the cooling tower body 3601. The V-shaped plates 3613 are located above the spray assembly. By setting the V-shaped plates 3613 above the spray assembly, water vapor in the exhaust gas is intercepted and flows back along the inclined V-shaped plates 3613, reducing the loss of cooling water and improving the utilization rate of cooling water.

[0177] The condensate from the 3000 membrane distillation system is returned to the ultrafiltration membrane raw water tank to dilute and adjust the concentration of the feed phosphoric acid, thus saving water consumption.

[0178] The steam generated by the membrane distillation system 3000 exchanges heat with the nanofiltration permeate, preheating the permeate before it enters the membrane distillation system. At the same time, it lowers the temperature of the steam, which helps to improve the efficiency of subsequent concentration and saves energy consumption of the membrane distillation system.

[0179] The membrane distillation system 3000 is arranged in two sections according to the concentration to be concentrated. The first section concentrates phosphoric acid to 60%, and the second section concentrates phosphoric acid to more than 60%, which can achieve more precise and efficient phosphoric acid concentration and meet the needs of phosphoric acid of different concentrations.

[0180] The ultrafiltration system 1000, nanofiltration system 2000 and membrane distillation system 3000 are all equipped with monitoring devices for various indicators such as flow rate, temperature, pressure, conductivity and pH. These devices monitor various parameters of the concentrated membrane system online, providing timely feedback on the system's operating status and ensuring process stability.

[0181] Furthermore, the ultrafiltration system 1000 and the nanofiltration system 2000 each have their own independent cleaning system.

[0182] The implementation principle of this embodiment is as follows: the water cooling tower 3600 sprays water into the cooling tower, the drive motor 3607 drives the spiral spray pipe 3606 to rotate, making the water mist more uniform and larger in range, and the jet pipe 3609 sprays low temperature air from below the heat dissipation packing 3608. The low temperature air and water mist exchange heat in the heat dissipation packing 3608 to achieve rapid cooling of high temperature water.

[0183] Example 5

[0184] like Figures 25 to 35 As shown, the ultrafiltration membrane box 1500 includes an ultrafiltration membrane box body 1501, a transmission screw 1502 rotatably connected to the four corners of the inner wall of the ultrafiltration membrane box body 1501, a sealing mechanism threadedly connected to the transmission screw 1502, a connecting rod opening and closing mechanism disposed at one end of the ultrafiltration membrane box body 1501, and an ultrafiltration membrane 1503 disposed between the sealing mechanisms.

[0185] like Figures 28 to 35As shown, the sealing mechanism includes several sealing plates 1504 slidably connected inside the ultrafiltration membrane housing 1500. The four corners of each sealing plate 1504 are threadedly connected to a drive screw 1502. Each pair of sealing plates 1504 forms a group, and ultrafiltration membranes 1503 are respectively disposed between two sealing plates 1504 in the same group. The threads on the two sealing plates 1504 in the same group have opposite directions. By setting the sealing plates 1504 threaded by the drive screw 1502 inside the ultrafiltration membrane housing 1501, and then assembling the ultrafiltration membrane 1503 into the ultrafiltration membrane housing 1501, the drive screw is rotated... Rotation of screw 1502, via the threaded transmission between the screw 1502 and the sealing plate 1504, causes the two sealing plates 1504 in the same group to move towards each other, clamping the ultrafiltration membrane 1503. This achieves the limiting of the ultrafiltration membrane 1503, improves the stability of the assembly of the ultrafiltration membrane 1503, and enhances the sealing performance between the ultrafiltration membranes 1503. When it is necessary to remove the ultrafiltration membrane 1503, simply rotate the screw 1502 in the opposite direction to separate the two sealing plates 1504 in the same group. This enables the rapid assembly and removal of the ultrafiltration membrane inside the ultrafiltration membrane housing, improving the sealing performance and stability of the ultrafiltration membrane assembly.

[0186] The shape of the sealing plate 1504 is adapted to the cross-sectional shape of the inner wall of the ultrafiltration membrane housing 1501. The coefficient of friction between the sealing plate 1504 and the inner wall of the ultrafiltration membrane housing 1501 is less than 0.5. A sealing ring is provided at the contact position between the sealing plate 1504 and the ultrafiltration membrane 1503. By limiting the shape and coefficient of friction of the sealing plate 1504, it can fully cooperate with the inner wall of the ultrafiltration membrane housing 1501, ensuring the sealing performance while allowing the sealing plate 1504 to slide smoothly inside the ultrafiltration membrane housing 1501 to clamp or release the ultrafiltration membrane 1503.

[0187] like Figures 28 to 34 As shown, a telescopic sealing sleeve 1505 is fixedly connected between two adjacent sealing plates 1504 that are not in the same group. The cross-sectional shape of the telescopic sealing sleeve 1505 is adapted to the shape of the sealing plate 1504. The telescopic stroke of the telescopic sealing sleeve 1505 is twice the sliding stroke of the sealing plate 1504. By setting the telescopic sealing sleeve 1505 between adjacent sealing plates 1504, the gap between the two sealing plates 1504 is sealed during the sliding process of the sealing plate 1504, thus avoiding the situation where phosphoric acid waste liquid accumulates in the gap between adjacent sealing plates 1504 without sufficient ultrafiltration treatment.

[0188] Furthermore, a wavy support strip is provided on the outer side of the sealing plate 1504 to improve the compressive strength of the sealing plate 1504. At the same time, the support strip is made of thermally conductive material, so that when the temperature of the ultrafiltration membrane is too high, the support strip can improve the heat dissipation efficiency of the ultrafiltration membrane 1503.

[0189] like Figures 25 to 27As shown, the linkage opening and closing mechanism includes three sets of transmission connecting rods 1506 that are respectively connected to the transmission screw 1502, a telescopic cylinder 1507 that is rotatably connected to one end of the ultrafiltration membrane housing 1501, and a connecting rod 158 that is disposed between the end of the transmission screw 1502 and the output end of the telescopic cylinder 1507.

[0190] A set of transmission connecting rods 1506 consists of three transmission rods. The ends of the set of transmission connecting rods 1506 are rotatably connected to two transmission screws 1502. The length of the longest transmission rod of the set of transmission connecting rods 1506 is equal to the distance between the two adjacent transmission screws 1502. The three transmission rods of the set of transmission connecting rods 1506 form an equilateral quadrilateral. By setting the transmission connecting rods 1502 at the ends of the ultrafiltration membrane housing 1501, the rotation of one of the transmission screws 1502 is controlled by the cooperation of the telescopic cylinder 1507 and the connecting rod 1508. Then, the three sets of transmission connecting rods 1506 drive the other three transmission screws 1502 to rotate, thereby realizing that one telescopic cylinder 1507 controls the rotation of four transmission screws 1502. Furthermore, one telescopic cylinder 1507 controls the opening and closing of all sealing components, realizing the rapid assembly, clamping and limiting of the ultrafiltration membrane 1503.

[0191] like Figures 25 to 29 As shown, an ultrafiltration inlet water pipe 1509 is provided at the bottom of the ultrafiltration membrane housing 1501. The water distribution pipes of the ultrafiltration inlet water pipe 1509 are located below each sealing mechanism. A filtrate collection pipe 1510 is provided on one side of the ultrafiltration housing 1501. The end of the filtrate collection pipe 1510 is connected to each ultrafiltration membrane 1503. An ultrafiltration outlet water pipe 1511 is provided on the other side of the ultrafiltration membrane housing 1501. The ultrafiltration outlet water pipe 1511 is connected to the ultrafiltration membrane housing 1501.

[0192] The implementation principle of this embodiment is as follows: A sealing plate 1504 controlled by a transmission screw 1502 is set inside the ultrafiltration membrane housing 1501. After the ultrafiltration membrane 1503 is assembled into the ultrafiltration membrane housing 1501, the transmission screw 1502 is rotated. Through the threaded transmission between the transmission screw 1502 and the sealing plate 1504, the two sealing plates 1504 in the same group move towards each other to clamp the ultrafiltration membrane 1503, thereby limiting the position of the ultrafiltration membrane 1503, improving the stability of the assembly of the ultrafiltration membrane 1503, and improving the sealing between the ultrafiltration membranes 1503. The opening and closing of multiple sets of sealing plates 1504 are controlled by the extension and retraction of the telescopic cylinder 1507.

[0193] The above description is only used to illustrate the technical solution of this utility model and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A full-membrane system for purifying and concentrating phosphoric acid waste liquid, characterized in that: The system includes an ultrafiltration system (1000), a nanofiltration system (2000), and a membrane distillation system (3000) arranged sequentially. The membrane distillation system (3000) includes a membrane distillation raw water tank (3100) connected to the outlet of the nanofiltration product water tank (2600) of the nanofiltration system (2000), a first heat exchanger (3200) connected to the outlet of the membrane distillation raw water tank (3100), a second heat exchanger (3300) connected to the outlet of the first heat exchanger (3200), a membrane distillation tank (3400) connected to the outlet of the second heat exchanger (3300), a condenser (3500) connected to the steam outlet of the first heat exchanger (3200), and a cooling tower (3600) circulatedly connected to the condenser (3500). The membrane distillation tank (3400) includes a membrane distillation tank body (3401), a steam inlet (3402) disposed on one side of the membrane distillation tank body (3401), a steam outlet (3403) disposed on the other side of the membrane distillation tank body (3401), a pure water outlet (3404) disposed on the top of the membrane distillation tank body (3401), a product water inlet (3405) disposed on one side of the bottom of the membrane distillation tank body (3401), a product water outlet (3406) disposed on the other side of the bottom of the membrane distillation tank body (3401), a distillation assembly disposed inside the membrane distillation tank body (3401), and a membrane cleaning assembly disposed on the top of the membrane distillation tank body (3401).

2. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 1, characterized in that: The ultrafiltration system (1000) includes an ultrafiltration raw water tank (1100), an ultrafiltration booster pump (1200) connected to the outlet of the ultrafiltration raw water tank (1100), an ultrafiltration filter (1300) connected to the outlet of the ultrafiltration booster pump (1200), an ultrafiltration circulation pump (1400) connected to the outlet of the ultrafiltration filter (1300), an ultrafiltration membrane tank (1500) connected to the outlet of the ultrafiltration circulation pump (1400), and an ultrafiltration product water tank (1600) connected to the product water outlet of the ultrafiltration membrane tank (1500). The outlet of the ultrafiltration product water tank (1600) is connected to the nanofiltration system (2000), and the pure water outlet of the ultrafiltration membrane tank (1500) is connected to the external drainage tank.

3. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 2, characterized in that: The nanofiltration system (2000) includes a nanofiltration raw water tank (2100) connected to the outlet of the ultrafiltration product water tank (1600), a nanofiltration booster pump (2200) connected to the outlet of the nanofiltration raw water tank (2100), a nanofiltration filter (2300) connected to the outlet of the nanofiltration booster pump (2200), a nanofiltration high-pressure pump (2400) connected to the outlet of the nanofiltration filter (2300), a nanofiltration membrane tank (2500) connected to the outlet of the nanofiltration high-pressure pump (2400), and a nanofiltration product water tank (2600) connected to the product water outlet of the nanofiltration membrane tank (2500). The outlet of the nanofiltration product water tank (2600) is connected to the membrane distillation system (3000), and the pure water outlet of the nanofiltration membrane tank (2500) is connected to the external drainage tank.

4. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 1, characterized in that: The distillation assembly includes a plurality of heating tubes (3407) fixedly connected inside the membrane distillation tank (3400), a pump (3408) disposed at the bottom of the heating tubes (3407), and a reflux tube (3409) disposed at the top of the heating tubes (3407).

5. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 1, characterized in that: The membrane cleaning assembly includes a servo motor (3410) fixedly connected to one side of the top of the membrane distillation tank (3401), and two steam filter membranes (3411) fixedly connected to the output end of the servo motor (3410).

6. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 1, characterized in that: The condenser (3500) includes a condenser tank (3501), a cooling water inlet (3502) at one end of the condenser tank (3501), a steam recovery port (3503) at the top of the other end of the condenser tank (3501), a condensate outlet (3504) at the bottom of the other end of the condenser tank (3501), a cooling water outlet (3505) at the top of the condenser tank (3501), a condensation assembly disposed inside the condenser tank (3501), and a support assembly disposed at the bottom of the condenser tank (3501).

7. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 6, characterized in that: The condensation assembly includes a plurality of condenser tubes (3506) fixedly connected inside the condenser tank (3501), a plurality of baffles (3507) disposed on the outside of the condenser tubes (3506), and a partition plate (3508) disposed at the end of the condenser tubes (3506).

8. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 1, characterized in that: The cooling tower (3600) includes a cooling tower body (3601), a cooling tower outlet (3602) located on one side of the bottom of the cooling tower body (3601), a cooling tower air inlet (3603) located on the other side of the bottom of the cooling tower body (3601), a spray assembly located on the upper half of the inner wall of the cooling tower body (3601), a cooling assembly located on the lower half of the inner wall of the cooling tower body (3601), and a heat dissipation assembly located on the top of the cooling tower body (3601).

9. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 8, characterized in that: The spray assembly includes an input pipe (3604) fixedly connected to the upper half of the inner wall of the cooling tower body (3601), a plurality of water distribution pipes (3605) fixedly connected to the input pipe (3604), and a plurality of spiral spray pipes (3606) rotatably connected to the bottom of the water distribution pipes (3605).

10. The all-membrane system for purifying and concentrating phosphoric acid waste liquid according to claim 8, characterized in that: The heat dissipation assembly includes an exhaust pipe (3610) disposed on both sides of the top of the cooling tower body (3601), a cooling fan (3611) disposed inside the exhaust pipe (3610), and a water separator (3612) disposed inside the exhaust pipe (3610).

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