阅读说明：本技术 一种耐碱可反洗管式膜元件及其管式膜组件 (Alkali-resistant backwashing tubular membrane element and tubular membrane assembly thereof ) 是由 庆天 于 2020-07-03 设计创作，主要内容包括：本发明公开了一种耐碱可反洗管式膜元件,由铸膜液层和无纺布层组成,所述铸膜液层中的铸膜液渗透入无纺布的内表面,并在无纺布外表面渗出,外表面有刮膜设备控制膜层厚度；所述无纺布层为加强无纺布。所述耐碱可反洗管式膜元件用于制作管式膜组件,所述管式膜组件可反洗、耐磨损、且具有高装填密度,其处理酸碱和高温废水具有高水处理效率,且操作简单,维护简单。(The invention discloses an alkali-resistant backwashing tubular membrane element, which consists of a membrane casting liquid layer and a non-woven fabric layer, wherein the membrane casting liquid in the membrane casting liquid layer permeates into the inner surface of a non-woven fabric and seeps out of the outer surface of the non-woven fabric, and the outer surface is provided with a membrane scraping device to control the thickness of the membrane layer; the non-woven fabric layer is a reinforced non-woven fabric. The alkali-resistant backwashing tubular membrane element is used for manufacturing a tubular membrane assembly, the tubular membrane assembly can be backwashed and is wear-resistant, the tubular membrane assembly has high filling density, and the tubular membrane assembly has high water treatment efficiency in acid-alkali and high-temperature wastewater treatment, and is simple to operate and simple to maintain.)

1. The utility model provides an alkali-resistant tubular membrane element that can backwash comprises membrane liquid layer and non-woven fabrics layer of casting, its characterized in that:

coating the casting solution in the casting solution layer on the inner surface of the non-woven fabric layer, permeating into the non-woven fabric layer, and permeating out of the outer surface of the non-woven fabric layer to form an inner-layer casting solution layer and a casting solution permeation layer; the thickness of the inner layer casting film liquid film layer is 10-50 μm;

the non-woven fabrics layer is a reinforced non-woven fabrics layer, and the reinforcing mode is as follows: firstly, winding a non-woven fabric strip into a pipe, arranging thin strip PE reinforcement on the outer surface of the non-woven fabric, wherein the width of the thin strip PE is 2-4mm, and the thickness of the thin strip PE is 0.1-0.3 mm; the distribution of the thin strip PE is as follows: thin strip-shaped PE is arranged in a range of 3-5mm from the edge of the non-woven cloth belt, and the distance between every two thin strip-shaped PE is 3-6 mm; secondly, thick strip-shaped PE is arranged to cover gaps among the non-woven fabric belts, the width of the thick strip-shaped PE is 3-5mm, and the thickness of the thick strip-shaped PE is 0.25-0.45 mm; thirdly, the thick strip PE and the thin strip PE are fixed on the surface of the non-woven fabric tube through ultrasonic welding;

the casting solution is alkali-resistant and can not be hydrolyzed in an alkaline environment, and the viscosity of the casting solution is 8000-13000mPa & s.

2. The tubular membrane module according to claim 1, wherein the casting solution forms an inner casting solution layer on the inner surface of the non-woven fabric, penetrates into the non-woven fabric, and forms an outer casting solution layer on the outer surface of the non-woven fabric; the thickness of the outer layer casting film liquid film layer is 10-50 μm.

3. The alkali-resistant backwashable tubular membrane element of claim 1, wherein the membrane casting solution is one or a mixture of PES \ PEK \ PEEK in any proportion.

4. The alkali-resistant backwashable tubular membrane element of claim 1 or 3, wherein the membrane casting solution comprises the following raw materials: 15-18% of PES and PEK mixed powder (2: 1), 8-10% of PVP, 0.5-1% of Al2O3, 1-2% of LiCl and the balance of N, N-dimethylacetamide.

5. The alkali-resistant backwashable tubular membrane element of claim 1, wherein the preparation method of the reinforced non-woven fabric layer comprises the following steps: the non-woven fabric belt is wound on the cylindrical pipe, the gaps of the non-woven fabric are covered by thick strip PE, and the non-woven fabric belt and the non-woven fabric are welded by ultrasonic waves to form a preliminarily reinforced non-woven fabric pipe; and ultrasonically welding thin strip PE on the outer surface of the preliminarily reinforced non-woven fabric pipe to obtain the reinforced non-woven fabric pipe.

6. The method for preparing the alkali-resistant backwashable tubular membrane element of claim 1, wherein a cylindrical tube is used, the cylindrical tube is hollow, one end of the cylindrical tube is connected with a casting film liquid pump, and the other end of the cylindrical tube is wrapped by non-woven fabrics; the end of the cylindrical pipe wrapped by the non-woven fabric is sealed, and 2-6 gaps with the length of 3-10mm and the width of 0.2-0.5mm are uniformly formed at a position 20mm away from the end along the circumference;

the cylindrical pipe is sleeved with a hollow cylindrical pipe, is an outer surface film scraping device, and has the length of 5-15cm and the thickness of 2-5 mm;

the difference between the diameter of the hollow cylindrical tube and the diameter of the non-woven fabric tube is within the range of the thickness +/-0.3 mm of the set finished film element;

adding various powders and solvents into a reaction kettle with a stirrer according to a ratio, reacting and stirring for 24 hours to obtain a membrane casting solution, standing and defoaming for 24 hours;

the casting solution enters the cylindrical pipe from the casting solution pump and flows out to the reinforced non-woven fabric pipe; the reinforced non-woven fabric tube rotates forwards under the traction of the belt, and the speed is 0.3-0.6 m/min; in the rotation process of the non-woven fabric tube, the membrane casting solution permeates into the inner surface of the non-woven fabric and seeps out of the outer surface of the non-woven fabric, and the thickness of the outer membrane is controlled by utilizing a gap between the outer surface membrane scraping device and the non-woven fabric tube;

cutting the non-woven fabric tube with the casting solution to a specified length,

slowly immersing the non-woven fabric into pure water to finish a phase inversion film forming process to form an initial tubular film element;

and soaking the initial tubular membrane element in pure water for 5-16h, taking out, and then soaking in the pure water to obtain the alkali-resistant tubular membrane element.

7. The use of an alkali-resistant tubular membrane element as claimed in claim 1, wherein the alkali-resistant tubular membrane element is used for preparing an alkali-resistant tubular membrane module capable of treating acid-base wastewater, the pH range is 0-14, and the concentration of sodium hydroxide in the alkali-base wastewater is less than or equal to 20%.

8. A tubular membrane component comprises alkali-resistant backwashing tubular membrane elements which are closely stacked, a diversion trench, a fastening device and a shell;

the fastening device is an elastic net or elastic cloth, and a tubular membrane element tightly stacked is sleeved in the fastening device;

the two diversion trenches are inserted into the cylindrical fastening device, abut against the fastening device, are uniformly distributed and have outward openings;

the tightly stacked tubular membrane elements and the peripheral diversion trenches are integrated into a bundle, so that the fastening device is cylindrical;

the cylindrical fastening device is sleeved in the shell, two ends of the shell are provided with openings, two sides of the shell are provided with openings, and the openings on the two sides are over against the openings of the diversion trench;

the two ends of the shell are sealed and fixed with the tubular membrane element through alkali-resistant high-temperature-resistant sealing epoxy resin glue, and the opening of the tubular membrane element is smooth and unsealed.

9. The tubular membrane assembly of claim 8, wherein the housing is made of glass fiber reinforced plastic or CPVC.

10. The tubular membrane assembly of claim 8, wherein the epoxy glue has a hardness of >80D at 70 ℃ after setting.

11. The tubular membrane module of claim 10, wherein 1-2% alumina powder is added to the epoxy glue.

Technical Field

The invention belongs to the technical field of polymer separation membranes, and particularly relates to an alkali-resistant backwashing tubular membrane element and a tubular membrane assembly thereof.

Background

The tubular membrane generally consists of a casting membrane liquid layer and a non-woven fabric layer, the application of the tubular membrane is restricted by the performances of the casting membrane liquid layer and the non-woven fabric layer, and the tubular membrane can only be applied to the field of neutral waste liquid treatment (pH = 4-10) at present. The performance of the membrane casting solution determines the performance of the water treatment membrane, and the membrane casting solution always has the common defects of organic polymers, such as no acid and alkali resistance, no high temperature resistance and the like. In some special industries, such as the field of strong acid and strong alkali, the application of the tubular membrane is restricted.

Most of the existing non-woven fabrics are polymers such as polyesters, which are not acid-base resistant, can be hydrolyzed in acid-base environment to cause structure disintegration, and cannot be used for water treatment in acid-base environment, and the acid-base resistant polypropylene is too soft, and the polyethylene is too hard, so that the non-woven fabrics are not beneficial to being used as a support body to prepare a tubular membrane element.

The conventional process for preparing the tubular membrane element is to cast the membrane casting solution on the inner surface of the non-woven fabric and then form a membrane by a phase inversion method. By adopting the process, the casting film liquid layer and the non-woven fabric layer are two systems, the mutual adhesive force is small, the casting film liquid layer is tightly attached to the non-woven fabric layer in the normal filtering process, the casting film liquid layer is a filtering layer, and the non-woven fabric layer is a supporting layer, so that the stable tubular membrane element is formed. And during backwashing, the feed liquid firstly passes through the non-woven fabric layer and then passes through the casting film liquid layer, the two-layer cohesive force is small, the casting film liquid layer cannot be supported, the casting film liquid layer is very easy to separate from the non-woven fabric, and finally the tubular film element loses the filtering effect, so the conventional tubular film element cannot be backwashed.

CN201880020284.7 provides a semipermeable membrane support, which is a wet nonwoven fabric comprising a core-sheath type composite fiber comprising polypropylene as a core component and polyethylene as a sheath component, and has a breaking strength of 300 to 1000 kPa. And a semipermeable membrane support which can withstand repeated washing and backwashing. However, the strength of the support body provided by the patent is too low to be suitable for long-term use and repeated backwashing in a high-pressure environment.

Disclosure of Invention

The invention provides a backwashing, wear-resistant and alkali-resistant tubular membrane element and an alkali-resistant backwashing tubular membrane assembly with high filling density, which are used for solving the problems that the existing organic tubular membrane is not acid and alkali resistant and can not be backwashed.

The alkali-resistant backwashing tubular membrane element consists of a membrane casting liquid layer and a non-woven fabric layer,

the casting film liquid in the casting film liquid layer permeates into the inner surface of the non-woven fabric and permeates out of the outer surface of the non-woven fabric, the thickness of the film layer is controlled by a film scraping device on the outer surface, tight anchoring of the film layer and the non-woven fabric is achieved, the binding force of the film layer and the non-woven fabric is increased, and the backwashing pressure performance is improved.

Coating the casting solution in the casting solution layer on the inner surface of the non-woven fabric layer, permeating the casting solution into the non-woven fabric layer, and permeating the casting solution out of the outer surface of the non-woven fabric layer to form an inner casting solution layer and a casting solution permeation layer; the thickness of the inner layer casting film liquid film layer is 10-50 μm.

The non-woven fabrics layer is a reinforced non-woven fabrics layer, and the reinforcing mode is as follows: firstly, winding a non-woven fabric strip into a pipe, arranging thin strip PE reinforcement on the outer surface of the non-woven fabric, wherein the width of the thin strip PE is 2-4mm, and the thickness of the thin strip PE is 0.1-0.3 mm; the distribution of the thin strip PE is as follows: thin strip-shaped PE is arranged in a range of 3-5mm from the edge of the non-woven cloth belt, and the distance between every two thin strip-shaped PE is 3-6 mm; secondly, covering gaps among the non-woven fabric belts by using thick strip-shaped PE, wherein the width of the thick strip-shaped PE is 3-5mm, and the thickness of the thick strip-shaped PE is 0.25-0.45 mm. And thirdly, the thick strip PE and the thin strip PE are fixed on the surface of the non-woven fabric tube through ultrasonic welding.

The casting solution is alkali-resistant and can not be hydrolyzed in an alkaline environment, and the viscosity of the casting solution is 8000-13000mPa & s.

The film casting solution not only forms an inner-layer film casting liquid layer on the inner surface of the non-woven fabric, but also permeates into the non-woven fabric, and forms an outer-layer film casting liquid layer on the outer surface of the non-woven fabric; the thickness of the outer layer casting film liquid film layer is 10-50 μm.

The casting film liquid is selected from one or a mixture of more of PES \ PEK \ PEEK in any proportion.

The raw material composition of the casting solution comprises: PES/PEK mixed powder (2: 1) 15-18%, PVP 8-10%, and Al₂O₃0.5-1% of LiCl, 1-2% of N, N-dimethylacetamide and the balance of the mixture.

Alumina is added into the raw materials of the membrane casting solution, and the alumina with the addition of 0.5-1% is uniformly dispersed in the membrane layer with the separation effect, so that the friction resistance function of the separation membrane can be obviously enhanced.

The preparation method of the tubular membrane element comprises the following steps:

the non-woven fabric belt is wound on the cylindrical pipe, the gaps of the non-woven fabric are covered by thick strip PE, and the non-woven fabric belt and the non-woven fabric are welded by ultrasonic waves to form a preliminarily reinforced non-woven fabric pipe;

and ultrasonically welding thin strip PE on the outer surface of the preliminarily reinforced non-woven fabric pipe to obtain the reinforced non-woven fabric pipe.

The preparation method of the tubular membrane element comprises the following steps:

(1) a cylindrical pipe is used, the cylindrical pipe is hollow, one end of the cylindrical pipe is connected with a casting film liquid pump, and the other end of the cylindrical pipe is wrapped by non-woven fabrics; the end of the cylindrical pipe wrapped by the non-woven fabric is sealed, and 2-6 gaps with the length of 3-10mm and the width of 0.2-0.5mm are uniformly formed at a position 20mm away from the end along the circumference; the cylindrical pipe is sleeved with a hollow cylindrical pipe, is an outer surface film scraping device, and has the length of 5-15cm and the thickness of 2 mm.

The difference between the diameter of the hollow cylindrical tube and the diameter of the non-woven fabric tube is within the range of +/-0.3 mm of the thickness of the set finished film element.

(2) Adding various powders and solvents into a reaction kettle with a stirrer according to a ratio, reacting and stirring for 24 hours to obtain a membrane casting solution, standing and defoaming for 24 hours;

the casting solution enters the cylindrical pipe from the casting solution pump and flows out to the reinforced non-woven fabric pipe; the reinforced non-woven fabric tube rotates forwards under the traction of the belt, and the speed is 0.3-0.6 m/min; in the rotation process of the non-woven fabric tube, the membrane casting solution permeates into the inner surface of the non-woven fabric and seeps out of the outer surface of the non-woven fabric, and the thickness of the outer membrane is controlled by utilizing a gap between the outer surface membrane scraping device and the non-woven fabric tube;

cutting the non-woven fabric tube with the casting solution to a specified length,

slowly immersing the non-woven fabric into pure water to finish the phase inversion film forming process to form the initial tubular film element.

(3) And soaking the initial tubular membrane element in pure water for 5-16h, taking out, and then soaking in the pure water to obtain the alkali-resistant tubular membrane element.

Soaking the initial tubular membrane element in pure water for 5-16h, taking out, soaking in pure water, pumping 0.6bar of compressed air into one end of the tubular membrane element, sealing the other end of the tubular membrane element by using a plug to ensure that the compressed air is not leaked, observing the whole element for 3 seconds by using eyes, and obtaining the qualified tubular membrane element if no air bubbles emerge from the outer surface of the element; if continuous bubbles emerge from the outer surface of the element, the tubular membrane element is unqualified.

The alkali-resistant tubular membrane element is used for preparing the alkali-resistant tubular membrane component capable of treating the acid-base wastewater,

the alkali-resistant tubular membrane component comprises tubular membrane elements which are tightly stacked, a diversion trench, a fastening device and a shell;

the fastening device is an elastic net or elastic cloth, and a tubular membrane element tightly stacked is sleeved in the fastening device;

the two diversion trenches are inserted into the cylindrical fastening device, abut against the fastening device, are uniformly distributed and have outward openings;

the tightly stacked tubular membrane elements and the peripheral diversion trenches are integrated into a bundle, so that the fastening device is cylindrical;

the cylindrical fastening device is sleeved in the shell, two ends of the shell are provided with openings, two sides of the shell are provided with openings, and the openings on the two sides are over against the openings of the diversion trench;

the two ends of the shell are sealed and fixed with the tubular membrane element through alkali-resistant high-temperature-resistant sealing epoxy resin glue, and the opening of the tubular membrane element is smooth and unsealed.

The shell can be made of glass fiber reinforced plastics or CPVC;

1-2% of aluminum oxide powder is added into the epoxy resin adhesive to improve the epoxy temperature resistance, so that the hardness of the epoxy resin is more than 80D at 70 ℃;

the alkali-resistant tubular membrane component is simple and stable in structure, easy to assemble and high in water treatment efficiency.

The diameters of the alkali-resistant tubular membrane components can be 4 inches, 6 inches, 8 inches and 10 inches; the maximum filling area of a single membrane component is 64m²。

Drawings

FIG. 1: the structure of the device for reinforcing the non-woven fabric is shown schematically.

FIG. 2 is an interior surface coating apparatus.

FIG. 3 is an apparatus for coating an outer surface of a substrate.

In the figure: 1 non-woven fabric, 2 welding heads, 3 driving wheels, 4 thin strip PE, 5 thick strip PE, 6 central shafts, 7 and a film scraping device.

Detailed Description