Flat membrane bag, flat membrane module

Abstract

The present invention discloses a flat membrane bag and a flat membrane module. The flat membrane bag includes at least two layers of flat membranes. A bag body is formed between adjacent flat membranes. The four sides of the bag body are respectively sealed and connected to form a sealing edge, and at least one raw water inlet opening communicating with the inside of the bag body is provided on the sealing edge. The flat membrane module includes a housing and a filter element located inside the housing. The filter element is formed by stacking a plurality of flat membrane bags. A raw water inlet pipe is provided on the housing, and a corresponding raw water inlet part is provided on the filter element. The raw water inlet openings are respectively located at the positions of the raw water inlet parts. The adjacent flat membrane bags at the raw water inlet parts are sealed and connected by sealant, and the four sides of the raw water inlet parts are sealed and connected to the inner wall of the housing by sealant. A plurality of water production channels are provided on the filter element, and water production openings respectively communicating with the water production channels are provided on the housing. The flat membrane module of the present invention has the advantages of large flux, low pressure difference, stable water outlet quality, no filament breakage, and long membrane life, and has a backwashing function.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a flat membrane bag and a flat membrane module. Background Art

[0002] At present, there are mainly three membrane structure forms in the field of membrane filtration and separation: hollow fiber, flat, and tubular modes. The main advantage of hollow fiber membranes is that they can be backwashed. The main advantage of tubular membranes is that they can withstand very high suspended solids. The main advantages of flat membranes are large flux, low pressure difference, and few membrane pore defects. Due to the above advantages, flat membranes have been made into various forms of filtration units or modules for practical use: membrane filter cores including dead-end filtration, which are applied to liquid clarification and sterilization filtration; cross-flow flat ultrafilters, which are applied to material separation and concentration; spiral wound membrane modules, which are applied to water body and material filtration, separation, and concentration.

[0003] However, the above-mentioned membrane units or modules all have some deficiencies. For example, the membrane filter cores of dead-end filtration are generally disposable, with high costs; spiral wound membranes generally cannot be backwashed, and the advantage of large flux cannot be exerted due to the limitation of the central tube; the initial investment of cross-flow flat ultrafilters is very high, and they are not very suitable for large-flow water treatment processes. Summary of the Invention

[0004] To solve the above problems, the present application aims to invent a flat membrane module that can exert the advantages of large flux and low pressure difference of flat membranes, and like hollow fiber membranes, has a backwashing function and can be applied to water body and aqueous solution filtration.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a flat membrane bag, including at least two layers of flat membranes. A bag body is formed between adjacent flat membranes. The four sides of the bag body are respectively sealed and connected to form a sealing edge. At least one raw water inlet opening communicating with the inside of the bag body is provided on the sealing edge. The flat membrane includes a separation layer and a support layer, and the separation layer is located inside the bag body.

[0006] Preferably, a raw water diversion net is provided inside the bag body.

[0007] Preferably, the width of the sealing edge is 1-10 millimeters.

[0008] Preferably, the thickness of the raw water diversion net is between 0.5-2.5 millimeters.

[0009] Flat membrane module, including a housing and a filter element located inside the housing. The filter element includes a plurality of flat membrane bags. The plurality of flat membrane bags are stacked in sequence in the thickness direction of the flat membrane bag to form the filter element. The housing is provided with a plurality of raw water inlet pipes communicating with the inside of the housing. The filter element is provided with a plurality of raw water inlet parts. The raw water inlet openings on the flat membrane bags are respectively located at the positions of the raw water inlet parts. The raw water inlet parts correspond to the raw water inlet pipes one by one. The adjacent flat membrane bags at the raw water inlet parts are sealed and connected by sealant. The periphery of the raw water inlet part is sealed and connected to the inner wall of the housing by sealant. The filter element is provided with a plurality of water production channels. The water production channels sequentially penetrate through all the flat membrane bags and respectively form water collection openings on each flat membrane bag. The water collection openings are isolated from the inside of the flat membrane bag by a sealing ring. The housing is provided with a plurality of water production ports respectively communicating with the water production channels.

[0010] As a preference of the above technical solution, the housing is a round tube with sealing caps at both ends. The filter element is cylindrical. The thickness direction of the flat membrane bag is perpendicular to the axis of the round tube. One raw water inlet pipe is respectively provided at both ends of the round tube. The two ends of the filter element are respectively set as raw water inlet parts. The number of water production channels is two.

[0011] As a preference of the above technical solution, sealing grooves are respectively provided at both ends of the filter element. The sealing grooves respectively communicate with the corresponding water production channels. Connecting pipes are inserted into the sealing grooves. The connecting pipes are respectively connected to the water production ports. Notches are provided on the edges of some flat membrane bags in the filter element. The sealing grooves are formed by the superposition of the notches of the stacked flat membrane bags. The notches are isolated from the inside of the bag body by a sealing line located around the notches.

[0012] As a preference of the above technical solution, a water production diversion net is provided between adjacent flat membrane bags in the filter element.

[0013] As a preference of the above technical solution, a woven net is provided outside the filter element.

[0014] As a preference of the above technical solution, the number of flat membranes in each flat membrane bag is two layers.

[0015] The beneficial effects of the present invention are as follows: The flat membrane module of the present invention gives full play to the advantages of large flux and low pressure difference of the flat membrane, and at the same time has an anti-flushing function like that of a hollow fiber membrane. It can be applied to the filtration of water bodies and aqueous solutions, such as in the field of protecting RO membranes. Compared with the currently commonly used hollow fiber membrane modules, the flat membrane module of the present invention has a large flux, a low pressure difference, stable effluent quality, no filament breakage, and a long membrane life. Description of the Drawings

[0016] Figure 1 It is a schematic cross-sectional structure diagram of the flat membrane bag;

[0017] Figure 2It is a schematic structural diagram of the notch on the flat membrane bag.

[0018] Figure 3 It is a schematic structural diagram of the water collection opening on the flat membrane bag.

[0019] Figure 4 It is a schematic structural diagram of the flat membrane bag and the water production diversion net in the flat membrane module.

[0020] Figure 5 It is a schematic structural diagram of the flat membrane module of the present invention.

[0021] Figure 6 It is a schematic cross-sectional view of the flat membrane module of the present invention.

[0022] Figure 7 It is a schematic structural diagram of the end of the filter element. Detailed implementation manners

[0023] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0026] Embodiment 1

[0027] As Figures 1-3As shown, the flat membrane bag 18 includes two layers of flat membranes 1. A bag body 2 is formed between adjacent flat membranes 1. The four sides of the bag body 2 are respectively sealed and connected to form a sealing edge 3. At least one raw water inlet opening 4 communicating with the inside of the bag body 2 is provided on the sealing edge 3. The flat membrane 1 includes a separation layer and a support layer, and the separation layer is located inside the bag body 2. Further, a raw water diversion net 5 is provided inside the bag body 2. Further, the width of the sealing edge is 1-10 millimeters. Further, the thickness of the raw water diversion net is between 0.5-2.5 millimeters. The raw water to be treated enters the inside of the bag body 2 from the raw water inlet opening 4, and the raw water permeates out of the bag body 2 through the filtration of the flat membrane 1 to form produced water. The raw water diversion net 5 is beneficial to the flow of raw water inside the bag body 2.

[0028] Example Two

[0029] As Figures 1-7As shown in the figure, a 4-inch flat microfiltration membrane module includes a housing 6 and a filter element located inside the housing 6. The housing is a circular tube with sealing caps 7 at both ends. A PVDF flat microfiltration membrane 1 with a filtration accuracy of 0.1 micron on the market is used, and a water production diversion net 10 made of PP material with a thickness of 36 mil is used. A number of flat membrane bags 18 with lengths of 1 meter and widths of 9.5 cm, 9 cm, 8 cm, 7 cm, 6 cm, 5 cm, 4 cm, 3 cm, and 2 cm are welded by hot melt welding. The widths of the flat membrane bags 18 and the water production diversion net 10 change in a stepped manner. If the stepped amplitude value is too large, the integrity of the circular cross-section is not good; if the stepped amplitude value is too small, the production is more cumbersome. Each flat membrane bag 18 includes two layers of flat microfiltration membranes 1. The raw water inlet openings 4 of the flat membrane bags 18 are located at both ends of the flat membrane bags 18 respectively, and the widths of the raw water inlet openings 4 are the same as the widths of their bag bodies 2. The width of the sealing edge 3 of the flat membrane bag 18 is 5 cm. At the upper and lower ends of the flat membrane bags 18 with widths of 9.5 cm, 8 cm, and 7 cm, a notch 8 with a depth of 8 cm and a width of 3 cm is opened respectively, and a sealing edge 3 is also welded around the notch 8. At both ends of the flat membrane bags 18 with widths from 5 cm to 2 cm, a closed hole with a diameter of 1 cm is opened as a water collection opening 9 for water production diversion, and this water collection opening 9 also serves as an auxiliary for sealant potting. The above-mentioned flat membrane bags 18 are alternately stacked with water production diversion nets 10 of the same width (thickness 0.25 mm) to form a cylindrical stack with a cross-section similar to a circle, and the diameter of the circular cross-section of this stack is 9.5 cm. The two ends of adjacent flat membrane bags 18 are sealed and bonded together by a sealant 11, and the water production diversion net 10 is fixedly clamped between adjacent flat membrane bags 18. A fiberglass mesh with a mesh size of 3*3 mm and a thickness of 1 mm is used as a braided mesh 12 to wind this stack to form a cylindrical filter element with a diameter close to 10 cm. On the one hand, the braided mesh 12 is used to reinforce the filter element to prevent the stack from collapsing; on the other hand, it makes the diameter of the filter element similar to the internal structure of the housing 6, so that the filter element can be exactly placed in the housing 6, and the filter element will not disintegrate during backwashing. The filter element is placed into the housing 6, and sealing caps are covered on both ends of the housing 6. The peripheries of both ends of the filter element are hermetically connected to the inner wall of the circular tube by a sealant 11. A raw water inlet part 13 is formed between the sealing cap 7 and both ends of the filter element. Raw water inlet pipes 14 communicating with the raw water inlet part 13 are respectively provided on the sealing cap 7. The notches 8 at both ends of the flat membrane bag 18 respectively form grooves 15 at both ends of the filter element. The upper part of the groove 15 is fixedly connected to a connecting pipe 16 by a sealant 11, and one end of the connecting pipe 16 extends out of the sealing cap 7 to form a water production port 17. The lower part of the groove 15 and other water collection openings respectively form two water production channels 19 at both ends inside the filter element.Raw water enters the raw water inlet part 13 from the raw water inlet pipe 14, and then enters each bag body 2 from the raw water inlet openings 4 respectively. After being filtered by the flat membrane bag 18, the produced water converges into the water production channel 19 from the gaps between adjacent flat membrane bags 18, and then is discharged from the water production port 17 through the connecting pipe 16. The water production diversion net 10 prevents adjacent flat membrane bags 18 from fitting under water pressure and affecting the water production efficiency.

[0030] In the actual production process, the raw water inlet openings do not need to be reserved in advance on the flat membrane bag 18. Instead, the four sides of the flat membrane bag 18 are hot melt welded to form a sealing edge 3. After assembling the filter element with sealant, the two ends of the filter element are cut to cut off the sealing edges 4 at both ends of the filter element, so that raw water inlet openings 4 communicating with the inside of the bag body can be formed at both ends of each flat membrane bag 18. The advantage of this operation is that it can avoid the sealant sticking to the raw water inlet openings 4 during the process of assembling the filter element, and improve the production efficiency of the filter element. After encapsulation and cutting, the filter element is obtained. Finally, the shell 6 and the sealing cover 7 are assembled to obtain a flat membrane microfiltration module that can be backwashed. The effective area of this flat membrane microfiltration module is 8 square meters.

[0031] The above-mentioned membrane module is tested with municipal tap water. At a pressure of 0.1 kg, the water permeability reaches 2 tons per hour, and the turbidity of the effluent is less than 0.1 NTU. It can be seen that this flat ultrafiltration membrane has a large flux and a low pressure difference. Every hour of operation, the membrane module is backwashed with the produced water for 30 seconds and flushed forward for 30 seconds (the water volume is 2 tons per hour), and then the membrane module is operated again. Within 8 cycles, the water production of the membrane and the initial pressure difference remain unchanged, indicating that this membrane module has very good backwashing and regeneration ability.

[0032] Example Three

[0033] 8-inch ultrafiltration membrane flat membrane module

[0034] As Figures 1-7 shown, the PVDF microfiltration membrane flat membrane 1 with a filtration accuracy of 0.03 microns on the market is used, and the raw water diversion net 5 made of PP material with a thickness of 36 mil is used. A number of flat membrane bags 18 with a length of 1 meter and widths ranging from 19.5 cm to 2 cm are welded by hot melt welding. The widths of the flat membrane bags 18 and the water production diversion net 10 change in a stepped manner, and the width reduction gradient is 1 cm. Each flat membrane bag 18 includes two layers of microfiltration membrane flat membranes 1. The raw water inlet openings 4 of the flat membrane bags 18 are located at both ends of the flat membrane bags 18 respectively, and the widths of the raw water inlet openings 4 are the same as the widths of their bag bodies 2. The width of the sealing edge 3 of the flat membrane bag 18 is 5 cm.

[0035] At the upper and lower ends of the flat membrane bag 18 with a width between 19.5 cm and 14 cm, a notch 8 with a depth of 10 cm and a width of 6 cm is opened, and a sealing edge 3 is also welded around the notch 8. On the flat membrane bag with a width between 13 cm and 6 cm, a closed hole with a diameter of 3 cm is opened, and on the flat membrane bag 18 with a width between 5 cm and 2 cm, a closed hole with a diameter of 1 cm is opened. The closed hole serves as the water production diversion collecting opening 9, and this collecting opening 9 also serves as an auxiliary for sealant potting. A number of the above flat membrane bags 18 are respectively stacked alternately with the water production diversion nets 10 of the same width to form a cylindrical stack with a cross-section similar to a circle. The diameter of this stack is about 19.5 cm, and the thickness of the water production diversion net is 0.25 mm. A fiberglass mesh with a mesh size of 3*3 mm and a thickness of 1 mm is used as the weaving mesh 12 to wrap this stack to form a filter element with a diameter close to 20 cm. The remaining encapsulation steps and methods are the same as those in the second embodiment, and finally an ultrafiltration membrane flat membrane module with an effective area of 32 square meters is formed.

[0036] The ultrafiltration membrane flat membrane module and a commercially available hollow membrane module with a pore size of 0.03 microns and an area of 55 square meters are applied to the comparative test of municipal tap water filtration. Under the same pressure difference, after 8 rounds of filtration and backwashing experiments, the flow rate of the product of this ultrafiltration membrane flat membrane module is 50% larger, and there is no obvious difference in the effluent turbidity.

[0037] It is worth mentioning that the technical features such as the flat membrane, hollow membrane module, and fiberglass mesh involved in this invention patent application should be regarded as the prior art. For the specific structures, working principles, and possible control methods and spatial arrangement methods involved in these technical features, conventional selections in this field can be adopted, and they should not be regarded as the inventive points of this invention patent, and this invention patent will not be further specifically elaborated.

[0038] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in this technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. Flat membrane module, Characterized in that, it includes a housing and a filter element located inside the housing, and the filter element includes a plurality of flat membrane bags, the flat membrane bag includes at least two layers of flat membranes, a bag body is formed between adjacent flat membranes, the four sides of the bag body are respectively sealed and connected to form a sealing edge, and at least one raw water inlet opening communicating with the inside of the bag body is provided on the sealing edge. The flat membrane includes a separation layer and a support layer. The separation layer is located inside the bag body. A raw water diversion net is provided inside the bag body. The width of the sealing edge is 1-10 mm, and the thickness of the raw water diversion net is between 0.5-2.5 mm; a plurality of the flat membrane bags are stacked in sequence in the thickness direction of the flat membrane bag to form a filter element. A plurality of raw water inlet pipes communicating with the inside of the housing are provided on the housing. A plurality of raw water inlet parts are provided on the filter element. The raw water inlet openings on the flat membrane bags are respectively located at the positions of the raw water inlet parts. The raw water inlet parts correspond to the raw water inlet pipes one by one. The adjacent flat membrane bags at the raw water inlet parts are sealed and connected by sealant. The periphery of the raw water inlet part is sealed and connected to the inner wall of the housing by sealant. A plurality of water production channels are provided on the filter element. The water production channels sequentially penetrate through all the flat membrane bags and respectively form water collection openings on each flat membrane bag. The water collection openings are isolated from the inside of the flat membrane bag by gaskets. A plurality of water production ports respectively communicating with the water production channels are provided on the housing; the housing is a round tube with sealing covers at both ends. The filter element is cylindrical. The thickness direction of the flat membrane bag is perpendicular to the axis of the round tube. One raw water inlet pipe is provided at each end of the round tube. The two ends of the filter element are respectively set as raw water inlet parts. The number of water production channels is two. Sealing grooves are respectively provided at the two ends of the filter element. The sealing grooves respectively communicate with the corresponding water production channels. Connecting pipes are inserted into the sealing grooves. The connecting pipes are respectively connected to the water production ports. Notches are provided on the edges of some flat membrane bags in the filter element. The sealing grooves are formed by superimposing the notches of the stacked flat membrane bags. The notches are isolated from the inside of the bag body by sealing lines located around the notches.

2. The flat membrane module according to claim 1, Characterized in that: a water production diversion net is provided between adjacent flat membrane bags in the filter element.

3. The flat membrane module according to claim 2, Characterized in that: a woven net is provided outside the filter element.

4. The flat membrane module according to claim 3, Characterized in that: the number of flat membranes in each flat membrane bag is two layers.

Images