Spacer for reverse osmosis element having excellent fouling resistance and reverse osmosis element including same

Abstract

The present invention relates to: a spacer (100) for a reverse osmosis element, the spacer having excellent fouling resistance; and a reverse osmosis element including same. The spacer for a reverse osmosis element of the present invention has superb fouling resistance, and the reverse osmosis element of the present invention has excellent fouling resistance and thus has the advantages that initial differential pressure is improved compared to the prior art, the increase in differential pressure over operation time is small, energy consumption during operation is reduced, and operation costs can be reduced.

Description

Spacer for reverse osmosis element with excellent fouling resistance and reverse osmosis element including the same

[0001] The present invention relates to a spacer for a reverse osmosis element with excellent fouling resistance and a reverse osmosis element including the same, and more particularly, to a spacer for a reverse osmosis element with enhanced fouling resistance and a reverse osmosis element having improved initial differential pressure and lower differential pressure increase over operating time than before, thereby reducing energy consumption and costs during operation.

[0002]

[0003] Depending on their pore size, membranes are classified into microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO).

[0004] Unlike osmosis, which causes water to move from an area of ​​lower concentration to an area of ​​higher concentration, reverse osmosis applies pressure to a solution of higher concentration, causing water to move to a solution of lower concentration. This process prevents large particles from passing through the filter, allowing only water to pass through, resulting in pure, clean water. This process is used in a variety of fields, including sterile water for medical use, purified water, and water for semiconductor manufacturing.

[0005] This reverse osmosis method utilizes a reverse osmosis element. The reverse osmosis element is composed of multiple layers of reverse osmosis membranes, spacers, and tricot filter channels, which surround the tube. Raw water is supplied from one end of the reverse osmosis element, and as it flows along the spacers, even fine contaminants sub-nanometer are filtered by the reverse osmosis membrane. The permeate is then extracted from the other end. The permeate filtered by the reverse osmosis membrane flows along the filter channel, enters through the tube's holes, and flows within the tube. Therefore, the reverse osmosis element uses a structure capable of withstanding high pressure to minimize pressure loss when the raw water flows.

[0006] The spacer serves as a passage for raw water to flow in and is formed in a mesh-like shape. When raw water flows into a spacer formed in a single shape, a pressure differential occurs due to the flow obstruction caused by the spacer. As operation continues, contaminants accumulate in the spacer, increasing the pressure differential. This leads to problems such as increased operating energy costs. In addition, the water permeation flux inevitably causes a concentration polarization phenomenon near the reverse osmosis membrane, and as this phenomenon worsens, the osmotic pressure near the reverse osmosis membrane increases, resulting in a problem of decreased water permeability. In relation to this, there is a need for a spacer that can increase the efficiency of a reverse osmosis filter module by reducing the generation of pressure differential and alleviating the concentration polarization phenomenon using a single spacer.

[0007] Furthermore, the application of reverse osmosis (RO) elements is steadily increasing in the sewage and wastewater reuse market. Compared to typical usage environments, raw waters such as sewage and wastewater contain a high concentration of organic matter, resulting in a relatively rapid increase in differential pressure. This requires high energy consumption, increasing operating costs. Therefore, a RO element capable of addressing this issue is needed.

[0008]

[0009] The first problem to be solved in the present invention is to provide a spacer for a reverse osmosis element having excellent fouling resistance.

[0010] The second problem to be solved in the present invention is to provide a reverse osmosis element having excellent fouling resistance, improved initial differential pressure compared to conventional devices, lower differential pressure increase over operating time, reduced energy consumption during operation, and reduced operating costs.

[0011]

[0012] In order to solve the first problem described above, a spacer (100) for a reverse osmosis element is provided, in which a plurality of first strands (101) are arranged parallel to each other, a plurality of second strands (102) intersecting the plurality of first strands (101) are arranged parallel to each other to form a parallelogram, and an internal angle (θ1) of the parallelogram in a direction parallel to the flow direction of raw water is 35 to 45 degrees.

[0013] Additionally, the SPI (Strand Per Inch) of at least one of the first strand (101) or the second strand (102) may be 4 to 7, preferably both may be 4 to 7, and most preferably both may be 4 to 6.

[0014] Furthermore, the spacer (100) may have a thickness of 31 to 35 mil.

[0015]

[0016] In order to solve the second problem described above, a reverse osmosis element including a spacer (100) for the reverse osmosis element is provided.

[0017] According to one embodiment of the present invention, the reverse osmosis element may include a tube (200) including an opening for receiving a permeate along a longitudinal direction, one or more reverse osmosis membranes (300) extending outwardly from the tube and wound around the tube, and a spacer (100) for the reverse osmosis element that contacts the one or more reverse osmosis membranes (300) and is wound around the tube (200).

[0018] Additionally, the spacer (100) of the reverse osmosis element may be provided between the reverse osmosis membranes (300).

[0019] In addition, when the reverse osmosis element is operated in raw water, the initial differential pressure of the reverse osmosis element measured under conditions 1) and 2) below may be 1.0 to 2.25 psig.

[0020] 1) 182 LPM ≤ Inlet flow ≤ 186 LPM

[0021] 2) Conditions of raw water: Electrical conductivity is 2700 to 2785 us / cm, temperature is 25.7 to 27.4 ℃, turbidity is 0.3 NTU, TOC is 3 to 5 ppm, COD is 2.3 to 3.7 ppm, BOD is 0.7 to 0.9 ppm, and pH is 8.2 to 8.4.

[0022] Furthermore, when the reverse osmosis element is operated in raw water, the differential pressure increase of the reverse osmosis element measured under condition 3) below may be 0.05 to 0.17 bar.

[0023] 3) Conditions of raw water: Electrical conductivity is 2700 to 2785 us / cm, temperature is 25.7 to 27.4 ℃, turbidity is 0.3 NTU, TOC is 3 to 5 ppm, COD is 2.3 to 3.7 ppm, BOD is 0.7 to 0.9 ppm, and pH is 8.2 to 8.4.

[0024] In this case, the above differential pressure increase represents the differential pressure that increases on average every day when the reverse osmosis element is operated in the raw water condition below for 3 days.

[0025]

[0026] The spacer for the reverse osmosis element according to the present invention has excellent fouling resistance.

[0027] In addition, the reverse osmosis element including the spacer according to the present invention has excellent fouling resistance, so that the initial differential pressure is improved compared to the conventional one, the differential pressure increase according to the operating time is low, energy consumption is reduced during operation, and operating costs are reduced.

[0028]

[0029] FIG. 1 is a plan schematic diagram of a spacer for a reverse osmosis element according to a preferred embodiment of the present invention.

[0030] FIG. 2 is a photographic image of a spacer according to a preferred embodiment of the present invention.

[0031] Figure 3 is a schematic diagram showing a reverse osmosis element to which the spacer is applied according to a preferred embodiment of the present invention.

[0032] Figure 4 is a graph showing the initial differential pressure according to the inlet flow rate of an improved product to which a spacer is applied according to a preferred embodiment of the present invention and a conventional product to which a conventional spacer is applied.

[0033]

[0034] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description have been omitted for clarity of description, and the same reference numerals are assigned to identical or similar components throughout the specification.

[0035] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, or combinations thereof.

[0036] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0037]

[0038] When using a conventional spacer, a pressure difference occurs due to the flow obstruction caused by the spacer, and as operation continues, contaminants accumulate in the spacer, increasing the pressure difference. This results in a problem of increased operating energy costs. In particular, in the case of the conventional spacer, there was a problem that contaminants easily accumulated because the angle of the internal angle of the parallelogram parallel to the flow direction of the raw water was 75 degrees or more.

[0039]

[0040] Reverse osmosis elements can also be used to treat sewage and wastewater. These raw waters, often containing a high concentration of organic matter, can easily contaminate the spacer, leading to a relatively rapid increase in differential pressure. This increase in differential pressure necessitates higher pressure to maintain filtration capacity, resulting in increased operating energy consumption and increased operating costs.

[0041]

[0042] Accordingly, the present invention seeks to solve the above-described problem by providing a spacer (100) for a reverse osmosis element, in which a plurality of first strands (101) are arranged parallel to each other, a plurality of second strands (102) intersecting the plurality of first strands (101) are arranged parallel to each other to form a parallelogram, and an internal angle (θ1) of the parallelogram in a direction parallel to the flow direction of raw water is 35 to 45 degrees. Through this, compared to conventional spacers, the angle between strands is reduced to reduce the initial differential pressure, and the differential pressure increase according to the operating time is suppressed, thereby reducing energy and cost during element operation.

[0043]

[0044] Hereinafter, the spacer (100) of the present invention will be described with reference to FIG. 1. First, a plurality of first strands (101) are arranged parallel to each other. In this case, the first strands (101) used can be used without limitation as long as they can form a mesh sheet of the spacer (100), and preferably, a copolymer composed of one or more of polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), or polyester can be used as the material of the mesh sheet. More preferably, a polyolefin copolymer in which polypropylene, polyethylene, or polypropylene and polyethylene are mixed at a certain ratio can be used.

[0045] According to one embodiment of the invention, the diameter of the first strand (101) may be 0.33 mm or more, and preferably 0.33 to 0.70 mm. However, this is merely one embodiment, and the present invention is not limited thereto. If the diameter of the first strand (101) is less than 0.33 mm, the strand thickness may be extremely low, making it difficult to manufacture it into an actual spacer (100).

[0046] The SPI (Strand Per Inch) of the first strand (101) may be 4 to 7, preferably 4 to 6, and more preferably 5. The SPI represents the number of strands within a 1-inch range in the vertical direction of the strands arranged in parallel. If the SPI is less than 4, the differential pressure within the module is very small, so that turbulence is too little, and thus the internal flow velocity is slow, making it easy for inorganic contamination to occur. On the other hand, if the SPI exceeds 7, the differential pressure is too large, so that turbulence is large, making it easy for organic contamination to occur.

[0047]

[0048] The following describes the second strands (102) arranged to intersect with the plurality of first strands (101). First, the second strands (102) are arranged in parallel. The material and SPI of the second strand (102) are the same as those described above in the description of the first strand (101), so detailed descriptions are omitted.

[0049] The diameter of the second strand may be 0.23 mm or more. Preferably, it may be 0.23 to 0.50 mm. However, this is merely an example, and the present invention is not limited thereto. If the diameter of the second strand (102) is less than 0.23 mm, the strand thickness may be extremely low, making it difficult to manufacture it into an actual spacer (100).

[0050]

[0051] Meanwhile, the SPI (Strand Per Inch) of at least one of the first strand (101) or the second strand (102) may be 4 to 7, preferably both the first strand (101) and the second strand (102) may be 4 to 7, and more preferably 4 to 6. Most preferably, both the first strand (101) and the second strand (102) may be 5. Meanwhile, the SPI of the second strand (102) described above may be automatically determined by the internal angle (θ1) of the parallelogram with the first strand (101) described above.

[0052]

[0053] In addition, the first strand (101) and the second strand (102) may be intersected to form a parallelogram in a two-dimensional plane, and preferably, may have a rhombus shape. The rhombus shape may have the narrowest area when the same thickness is present compared to a circle or a rectangle. Therefore, the flow path of the spacer (100) composed of strands having a rhombus-shaped cross-section may be narrowed, thereby reducing the resistance to the flow of the reverse osmosis element and reducing the differential pressure.

[0054]

[0055] Referring to Figure 1, the flow direction of the raw water is parallel to the acute angle direction of the parallelogram. If the flow of the raw water flows in the acute angle direction, it does not easily separate from the strands and flows along the strands for a relatively long time before separation occurs. This can improve the differential pressure of the reverse osmosis element. If the angle (θ1) of the parallelogram described below exceeds 45°, the flow of the raw water may easily cause separation from the strands and the flow of the raw water may have difficulty spreading.

[0056] The internal angle (θ1) of the above parallelogram may be 35 to 45°, preferably 38 to 42°. Accordingly, θ2 may be 135 to 145°, preferably 138 to 142°. In the conventional case where the value of θ1 is 75 to 90°, there was a problem that pollutants were easily spread along the flow of raw water, resulting in contamination, easily increasing the differential pressure or having a high initial differential pressure. In addition, when θ1 is less than 35°, the differential pressure becomes too low, resulting in too little turbulence, which may slow down the internal flow velocity and cause inorganic contamination. If θ1 exceeds 45°, the flow of raw water is likely to cause separation in the strand, and the flow of raw water may easily spread out, and accordingly, the flow resistance of raw water on the spacer may increase, which may increase the initial differential pressure. In addition, since the differential pressure is too large, turbulence may be large, and organic contamination may easily occur, so the intended effect of the present invention may not be obtained.

[0057]

[0058] In order to solve the above-described problem, a reverse osmosis element including the spacer (100) for the reverse osmosis element is provided. Hereinafter, this will be described with reference to FIG. 3. In the present invention, the element including the spacer (100) may have a conventional structure. Specifically, the reverse osmosis element may include a tube (200) including an opening for receiving a permeate along a longitudinal direction, one or more reverse osmosis membranes (300) extending outwardly from the tube (200) and wound around the tube (200), and the spacer (100) for the reverse osmosis element contacting the one or more reverse osmosis membranes (300) and wound around the tube.

[0059] The above spacer (100) is positioned between the reverse osmosis membranes (300) to maintain a constant gap between the reverse osmosis membranes (300). Therefore, the spacer (100) may be configured in the form of a mesh in which multiple strands have constant intersections so that contaminants contained in the raw water can flow without accumulating.

[0060] In addition, the spacer (100) plays a role in forming a flow path inside the leaf in the reverse osmosis element. Specifically, the spacer (100) is positioned inside the leaf formed by bending the reverse osmosis membrane (300), and thus can greatly improve the formation of a flow path inside the leaf as a feed channel.

[0061] The thickness of the spacer (100) may be 31 to 35 mil, preferably 33 to 35 mil. When the thickness is converted to SI units, it may be 787.4 to 889 μm, preferably 838.2 to 889 μm. If it is thinner than 31 mil, contaminants in the raw water may block the flow path or the power of the pump that ejects the raw water may increase. On the other hand, if it is thicker than 35 mil, the differential pressure is too low and turbulence is too little, so the internal flow velocity is slow and inorganic contamination can easily occur. In addition, the outer diameter of the filter is fixed, but if the spacer (100) is too thick, the insertion area of ​​the reverse osmosis membrane (300) is reduced, which may be detrimental to the filtration function.

[0062] Additionally, the thickness of the spacer (100) may be smaller than the sum of the diameters of the first strand and the second strand. This is because, when manufacturing the spacer, a process of compressing the first strand and the second strand may be performed, and the thickness at the intersection of the first strand and the second strand may become smaller than the sum of the diameters of the first strand and the second strand due to the compression.

[0063]

[0064] The following describes a tube (200). The tube (200) may be formed as a hollow pipe member with one or both ends open and at least one hole through which product water flows. Any known tube applicable to the reverse osmosis element may be used without limitation, and thus the present invention does not specifically limit this.

[0065] The following describes a reverse osmosis membrane (300). Influent water passes through a spacer (100) and the reverse osmosis membrane (300). In the process of passing through the reverse osmosis membrane (300), dissolved salts and organic matter are excluded and pure water is separated. The element may include a tricot filter (400). In this case, the separated water may flow along the tricot filter (400), and the separated water is collected in a tube (200) located at the center and discharged outside the reverse osmosis element.

[0066] In addition, the reverse osmosis membrane (300) can be used without limitation as long as it is a known reverse osmosis membrane (300) that can be applied to the element, and thus the present invention does not specifically limit it.

[0067]

[0068] When a reverse osmosis element employing the spacer of the present invention described above is operated in raw water, the initial differential pressure of the reverse osmosis element measured under conditions 1) and 2) below may be 1.0 to 2.25 psig. This may be converted to 0.069 to 0.16 bar. This allows the initial differential pressure to be reduced compared to conventional methods, thereby reducing operating energy and costs.

[0069] 1) 182 LPM ≤ Inlet flow ≤ 186 LPM

[0070] 2) Conditions of raw water: Electrical conductivity is 2700 to 2785 us / cm, temperature is 25.7 to 27.4 ℃, turbidity is 0.3 NTU, TOC is 3 to 5 ppm, COD is 2.3 to 3.7 ppm, BOD is 0.7 to 0.9 ppm, and pH is 8.2 to 8.4.

[0071] Preferably, when the reverse osmosis element is operated in raw water under the above condition 2), when the inlet flow rate is 184 LPM, the initial differential pressure of the reverse osmosis element may be 1.0 to 2.25 psig.

[0072] Meanwhile, the initial differential pressure refers to the difference between the inlet pressure and the concentrated water pressure, and refers to the average of the values ​​measured within 30 minutes from immediately after operation when the reverse osmosis element is operated on raw water.

[0073] A reverse osmosis element including a spacer (100) of the present invention can have an initial differential pressure reduced by -40% or more compared to a conventional product.

[0074] The above turbidity refers to the degree of cloudiness of water, and refers to the degree to which the liquid appears cloudy due to a large number of contaminants that can be seen with the naked eye. In addition, TOC refers to Total Organic Carbon, which indicates the total amount of carbon that makes up the organic matter present in the raw water. And COD (Chemical Oxygen Demand) refers to chemical oxygen demand, which is the amount of oxygen required to chemically oxidize various contaminants present in the raw water. Furthermore, BOD (Biochemical Oxygen Demand) refers to biological oxygen demand, which is the amount of oxygen required by microorganisms to decompose various contaminants present in the water.

[0075]

[0076] When the above reverse osmosis element is operated in raw water, the differential pressure rise of the reverse osmosis element measured under condition 3) below can be 0.05 to 0.17 bar. This reduces the differential pressure rise compared to the past, thereby reducing operating energy and costs.

[0077] 3) Conditions of raw water: Electrical conductivity is 2700 to 2785 us / cm, temperature is 25.7 to 27.4 ℃, turbidity is 0.3 NTU, TOC is 3 to 5 ppm, COD is 2.3 to 3.7 ppm, BOD is 0.7 to 0.9 ppm, and pH is 8.2 to 8.4.

[0078] The above differential pressure increase represents the average daily increase in differential pressure when the reverse osmosis element is operated in the raw water condition below for three days.

[0079] The differential pressure generally increases with increasing raw water contamination and over time. If the differential pressure exceeds 0.17 bar, the operating pressure required to operate the reverse osmosis element increases, resulting in increased energy consumption and operating costs. This may make it difficult to achieve improved performance compared to conventional products.

[0080] In addition, since turbidity, TOC, COD, and BOD under the above raw water conditions are as described above, specific details are omitted.

[0081]

[0082] The present invention will be described in more detail through the following examples, but the following examples do not limit the scope of the present invention, and should be interpreted as helping to understand the present invention.

[0083]

[0084] <Example>

[0085] Example 1

[0086] A first strand (101) made of polypropylene and having a thickness of 658 μm and a second strand (102) made of polypropylene and having a thickness of 464 μm were prepared. Using the strands, a spacer as shown in Fig. 1 was manufactured using a manufacturing method conventional in the art.

[0087] The above spacer (100) has an SPI of 5 for each of the first strand (101) and the second strand (102), an internal angle (θ1) of a parallelogram in a direction parallel to the flow direction of the raw water is 40°, and a thickness of 34 mil.

[0088] Afterwards, a reverse osmosis element having an outer diameter of 8 inches as shown in Fig. 3 was manufactured using a tube (manufactured by SAMYOUNG ENP), a reverse osmosis membrane (manufactured by TORAY Advanced Materials Korea), a tricot filter (manufactured by TORAY Advanced Materials Korea), and the spacer, using a manufacturing method conventional in the art.

[0089]

[0090] Example 2

[0091] A reverse osmosis element as shown in Table 1 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 6.

[0092]

[0093] Example 3

[0094] A reverse osmosis element as shown in Table 1 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 7.

[0095]

[0096] Example 4

[0097] A reverse osmosis element as shown in Table 1 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 8.

[0098]

[0099] Example 5

[0100] A reverse osmosis element as shown in Table 1 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 9.

[0101]

[0102] Example 6

[0103] A reverse osmosis element as shown in Table 1 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 3.

[0104]

[0105] <Comparative Example>

[0106] Comparative Example 1

[0107] A reverse osmosis element as shown in Table 2 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 5 and the internal angle (θ1) was set to 90°.

[0108]

[0109] Comparative Example 2

[0110] A reverse osmosis element as shown in Table 2 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 5 and the internal angle (θ1) was set to 75°.

[0111]

[0112] Comparative Example 3

[0113] A reverse osmosis element as shown in Table 2 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 5 and the internal angle (θ1) was set to 50°.

[0114]

[0115] Comparative Example 4

[0116] A reverse osmosis element as shown in Table 2 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 5 and the internal angle (θ1) was set to 30°.

[0117]

[0118] Comparative Example 5

[0119] A reverse osmosis element as shown in Table 2 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each set to 5 and the internal angle (θ1) was set to 140˚.

[0120]

[0121] Comparative Example 6

[0122] A reverse osmosis element as shown in Table 2 was manufactured in the same manner as Example 1, except that the SPI of the first strand (101) and the second strand (102) were each 9 and the internal angle (θ1) was 90°.

[0123]

[0124] <Experimental Example>

[0125] Experimental Example 1: Initial Differential Pressure Measurement

[0126] Reverse osmosis element products were simultaneously installed at positions A and B in an 8-inch pressure vessel, and the initial differential pressure was obtained by measuring the differential pressure at a raw water inlet flow rate of 184 LPM (production flow rate 27.6 LPM, concentrated flow rate 156.4 LPM).

[0127] The initial differential pressure above refers to the difference between the inlet pressure and the condensate pressure, and is the average of the values ​​measured within 30 minutes after the reverse osmosis element was operated on raw water. The inlet pressure and condensate pressure were measured using pressure gauges attached to the 8-inch pressure vessel.

[0128] At this time, the raw water has an electrical conductivity of 2700 to 2785 us / cm, a temperature of 25.7 to 27.4°C, a turbidity of 0.3 NTU, a TOC of 3 to 5 ppm, a COD of 2.3 to 3.7 ppm, a BOD of 0.7 to 0.9 ppm, and a pH of 8.2 to 8.4.

[0129] The initial differential pressure of the reverse osmosis elements of Examples 1 to 6 and Comparative Examples 1 to 6 was measured by the above-described method and is shown in Tables 1 and 2.

[0130] In addition, the initial differential pressure of the reverse osmosis element manufactured in Example 1 and the reverse osmosis element manufactured in Comparative Example 6 was measured by the initial differential pressure measurement method, and the initial differential pressure was measured while changing the inlet flow rate, and the results are shown in Table 3 and Fig. 4.

[0131]

[0132] Experimental Example 2: Measurement of differential pressure rise

[0133] After obtaining the initial differential pressure (inlet pressure - concentration pressure) as in Experimental Example 1, the differential pressure increase was calculated by obtaining the final differential pressure (inlet pressure - concentration pressure) after operating the reverse osmosis element for 3 days in raw water (electrical conductivity of 2700 to 2785 us / cm, temperature of 25.7 to 27.4 ℃, turbidity of 0.3 NTU, TOC of 3 to 5 ppm, COD of 2.3 to 3.7 ppm, BOD of 0.7 to 0.9 ppm, pH of 8.2 to 8.4). Then, the average daily increase in differential pressure was calculated using this.

[0134] As in Experimental Example 1, the initial differential pressure and final differential pressure were measured at a raw water inlet flow rate of 184 LPM (production flow rate of 27.6 LPM, concentrated flow rate of 156.4 LPM) with one reverse osmosis element product each installed at positions A and B in an 8-inch pressure vessel.

[0135] The differential pressure rise of the reverse osmosis elements of Examples 1 to 6 and Comparative Examples 1 to 6 was measured by the above-described method, and the results are shown in Tables 1 and 2.

[0136]

[0137] SPIθ1 Angle (˚) Initial Differential Pressure (psig) Differential Pressure Rise (bar) First Strand Second Strand Example 155 402.11 0.144 Example 266 402.17 0.163 Example 377 402.21 0.185 Example 488 402.24 0.194 Example 599 402.23 0.223 Example 633 401.30 0.175

[0138] SPIθ1Angle (˚)Initial differential pressure (psig)Differential pressure rise (bar)First strandSecond strandComparative example 155902.420.270Comparative example 255752.350.211Comparative example 355502.260.189Comparative example 455301.590.194Comparative example 5551406.800.454Comparative example 699903.900.336

[0139] Inlet flow rate (LPM)Production flow rate (LPM)Concentrated flow rate (LPM)Example 1Comparative example 6Initial Differential Pressure (psig)Initial Differential Pressure (psig)8012680.61.3289.613.576.10.711.5711116.594.50.982.19130.419.5110.91.252.99148.522.51261.58-171.425.5145.91.98-18427.6156.42.113.9214.532.2182.32.875.8236.435.2201.23.4-241.2536.75204.53.527.1266.540.52264.138.4296452514.92-

[0140] Referring to Tables 1, 2, and 3, in Examples 1 to 6 and Comparative Example 4, since the θ1 angle was 45° or less, the flow of raw water did not separate well and flowed along the strand for a relatively long time, so the initial differential pressure was 2.25 psig or less. In contrast, in Comparative Examples 1 to 3, 5, and 6, since the θ1 angle exceeded 45°, the initial differential pressure exceeded 2.25 psig. In Comparative Example 4, since the θ1 angle was less than 35°, there was too little turbulence, so the internal flow velocity was slow, which could cause inorganic contamination, and the differential pressure increase was relatively high at 0.194 bar. In addition, in Examples 4 to 6, as the strand SPI was outside the range of 4 to 7, turbulence did not occur properly, resulting in inorganic or organic contamination, and accordingly, the differential pressure increase was higher than in Examples 1 to 3.

[0141] Example 3 had a strand SPI of 7, so the initial differential pressure and differential pressure increase were higher than those of Examples 1 and 2, and Example 2 had a strand SPI of 6, so the initial differential pressure and differential pressure increase were higher than those of Example 1, which had a strand SPI of 5.

[0142] That is, since Example 1, in which the θ1 angle is 35 to 45° and the first strand and the second strand are 5, showed superior initial pressure difference and pressure difference increase compared to other examples and comparative examples, it was confirmed that Example 1 had the best contamination resistance.

[0143]

[0144] Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiment presented in this specification, and a person skilled in the art who understands the spirit of the present invention will be able to easily propose other embodiments by adding, changing, deleting, or adding components within the scope of the same spirit, but this will also be considered to fall within the spirit of the present invention.

Claims

1. A plurality of first strands (101) are arranged parallel to each other, and a plurality of second strands (102) intersecting the plurality of first strands (101) are arranged parallel to each other to form a parallelogram. A spacer for a reverse osmosis element in which the interior angle (θ1) of a parallelogram in a direction parallel to the flow direction of the raw water is 35 to 45˚.

2. In paragraph 1, A spacer for a reverse osmosis element, characterized in that at least one of the first strand (101) or the second strand (102) has an SPI (Strand Per Inch) of 4 to 7.

3. In paragraph 2, A spacer for a reverse osmosis element, characterized in that the SPI (Strand Per Inch) of the first strand (101) and the second strand (102) are both 4 to 7.

4. In paragraph 2, A spacer for a reverse osmosis element, characterized in that the SPI (Strand Per Inch) of both the first strand (101) and the second strand (102) is 4 to 6.

5. In paragraph 1, The spacer (100) is a spacer for a reverse osmosis element, characterized in that its thickness is 31 to 35 mil.

6. A reverse osmosis element comprising a spacer (100) for a reverse osmosis element according to any one of claims 1 to 5.

7. A tube (200) including an opening for receiving a permeate along the length direction; One or more reverse osmosis membranes (300) extending outwardly from the tube and wound around the tube; and A reverse osmosis element characterized by comprising a spacer (100) for a reverse osmosis element of any one of claims 1 to 5, which is in contact with one or more of the reverse osmosis membranes and is wound around the tube.

8. In paragraph 7, A reverse osmosis element characterized in that the above spacer (100) is provided between reverse osmosis membranes (300).

9. In paragraph 7, A reverse osmosis element characterized in that, when the above reverse osmosis element is operated in raw water, the initial differential pressure of the reverse osmosis element measured under the following conditions 1) and 2) is 1.0 to 2.25 psig: 1) 182 LPM ≤ Inlet flow ≤ 186 LPM 2) Conditions of raw water: Electrical conductivity is 2700 to 2785 us / cm, temperature is 25.7 to 27.4 ℃, turbidity is 0.3 NTU, TOC is 3 to 5 ppm, COD is 2.3 to 3.7 ppm, BOD is 0.7 to 0.9 ppm, and pH is 8.2 to 8.

4.

10. In paragraph 7, A reverse osmosis element characterized in that, when the above reverse osmosis element is operated in raw water, the differential pressure increase of the reverse osmosis element measured under the following condition 3) is 0.05 to 0.17 bar: 3) Conditions of raw water: Electrical conductivity is 2700 to 2785 us / cm, temperature is 25.7 to 27.4 ℃, turbidity is 0.3 NTU, TOC is 3 to 5 ppm, COD is 2.3 to 3.7 ppm, BOD is 0.7 to 0.9 ppm, and pH is 8.2 to 8.

4. The above differential pressure increase represents the average daily increase in differential pressure when the reverse osmosis element is operated in the raw water condition below for three days.

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