Patent Description:
The present invention relates to the use of a reverse osmosis spacer and a reverse osmosis element with a high recovery rate, and more particularly, to a reverse osmosis spacer and a reverse osmosis element with a high recovery rate, which are capable of increasing a flow rate of produced water and decreasing less a salt removal rate in the reverse osmosis element during an operation at a high recovery rate with a structure of the reverse osmosis spacer that constitutes the reverse osmosis element.

Earth is a planet where water occupies <NUM>% of the surface thereof. Seawater accounts for <NUM>% of the total amount of water, and the seawater cannot be used as drinking water. Accordingly, a seawater desalination technology has been developed which removes salt dissolved in seawater and converts seawater into fresh water that can be used as drinking water. In the past, a method of producing pure water by boiling seawater and collecting moisture vapor was used. However, recently, a method for producing pure water using a reverse osmosis filter has been used as a core technique for seawater desalination.

Unlike osmosis in which water moves from a site with a low concentration to a site with a high concentration, the reverse osmosis is a phenomenon in which pressure is applied to a high-concentration solution to move water to a low-concentration solution. While coarse salt or contaminants cannot pass through the filter, only water passes through the filter, such that pure and clean water may be obtained. The reverse osmosis is used in various fields for producing sterile water for medical use, purified water, and water for semiconductor manufacturing.

A reverse osmosis element using such a reverse osmosis has been used. The reverse osmosis element is configured by stacking a plurality of reverse osmosis membranes, a plurality of feed spacers, and a plurality of transmissive spacers. The reverse osmosis element surrounds a water collecting pipe. When raw water is supplied to one side of the reverse osmosis element, fine contaminants less than nanometers are filtered out by the reverse osmosis membrane while the raw water flows along the feed spacers, and permeable water is taken out from the other side of the reverse osmosis element. The permeable water filtered by the reverse osmosis membrane flows along the transmissive spacers, flows into holes in the water collecting pipe, and then flows in the water collecting pipe. Therefore, in order to reduce a pressure loss when the raw water flows, the reverse osmosis element has a structure capable of withstanding high pressure. In general, a mesh-shaped spacer is used as the feed spacer, whereby a flow path of the raw water is ensured, a flow of raw water increases, and ion polarization occurring at an interface of the reverse osmosis membrane is mitigated.

Unlike the reverse osmosis elements for industrial (BW) and seawater desalination (SW), the reverse osmosis element for home use in the related art operates at a raw water concentration of <NUM> ppm, an operating pressure of <NUM> to <NUM> psi, and a recovery rate of <NUM>% and has a low flow rate of produced water. However, if the reverse osmosis element operates at a high recovery rate of <NUM> to <NUM>% in order to increase a flow rate of produced water, there is a problem in that a salt removal rate is decreased by about <NUM>% in comparison with when the reverse osmosis element operates at a low recovery rate. <CIT> discloses a reverse osmosis element and spacer wherein the spacer has a mesh shape comprised of a plurality of strands, said strands having a predetermined intersection point, a thickness of the spacer of <NUM>-<NUM> (<NUM>-<NUM> mil), an angle between the intersection points of from <NUM>-<NUM>° and a strand spacing of <NUM>-<NUM> SPI.

<CIT> discloses a spacer for a reverse osmosis element with a high recovery rate even at low pressures which has a stacked tricot filtration fabric layer. The tricot filtration fabric layer has an angle of intersection of <NUM>-<NUM>° and a thickness of <NUM>-<NUM> (<NUM> to <NUM> mil).

<CIT> discloses in Example <NUM> a feed side channel spacer with a two-layer structure, a thickness of <NUM> (=<NUM> mil) an inclination angle of <NUM>° ,an intersection interval of <NUM>, a distance between fibrous materials of <NUM>, and a recovery ratio of <NUM> % and in Example <NUM>, a feed side channel spacer with a two-layer structure with a thickness of <NUM> (=<NUM> mil), an inclination angle of <NUM>° an intersection interval of <NUM> and a distance between fibrous materials of <NUM>.

The present invention has been made in an effort to solve the above-mentioned problem, and an object of the present invention is to provide the use of a reverse osmosis element with a high recovery rate, which is capable of reducing ion polarization in the reverse osmosis element by creating an effective flow of raw water at an interface of a reverse osmosis membrane of the reverse osmosis element.

The reverse osmosis spacer with a high recovery rate is capable of decreasing less a salt removal rate by increasing a flow rate of produced water when a reverse osmosis element operates at a high recovery rate of <NUM>%.

A reverse osmosis spacer with a high recovery rate has a mesh shape having a plurality of strands having predetermined intersection points and operates at a recovery rate of <NUM>%.

In addition, a thickness of the reverse osmosis spacer with a high recovery rate is <NUM> (<NUM> mil).

In addition, an angle at one side between the intersection points between the strands is <NUM>°.

In addition, SPI (stand per Inch) of the strands is <NUM>.

In addition, the strands form a mesh having a two-layer structure.

A reverse osmosis element with a high recovery rate used according to the present invention includes the reverse osmosis spacer with a high recovery rate.

In addition, the reverse osmosis element includes :.

In addition, the reverse osmosis element with a high recovery rate operates pressure of <NUM> kPa (<NUM> psi).

In addition, the reverse osmosis element operates at raw water concentration of <NUM> ppm.

In addition, the reverse osmosis spacer with a high recovery rate may be stacked multiple times.

According to the present invention, it is possible to use the reverse osmosis element with a high recovery rate, which is capable of reducing ion polarization in the reverse osmosis element by creating an effective flow of raw water at the interface of the reverse osmosis membrane of the reverse osmosis element.

In addition, according to the present invention, it is possible to provide the reverse osmosis spacer with a high recovery rate, which is capable of decreasing less a salt removal rate by increasing a flow rate of produced water when the reverse osmosis element operates at a high recovery rate of <NUM>%.

<FIG> is a perspective view of a reverse osmosis element <NUM> with a high recovery rate used in the present invention.

Here, repeated descriptions and detailed descriptions of publicly-known functions and configurations, which may unnecessarily obscure the subject matter of the present invention, will be omitted. Exemplary embodiments of the present invention are provided to completely explain the present invention to a person with ordinary skill in the art. Therefore, shapes and sizes of elements illustrated in the drawings may be exaggerated for a more apparent description.

Throughout the specification, unless explicitly described to the contrary, the word "comprise" or "include" and variations, such as "comprises", "comprising", "includes" or "including", will be understood to imply the inclusion of stated constituent elements, not the exclusion of any other constituent elements.

Hereinafter, exemplary embodiments are proposed to help understand the present invention. However, the following exemplary embodiments are provided just for more easily understanding the present invention, and the contents of the present invention are not limited by the exemplary embodiments.

<FIG> is a perspective view of a reverse osmosis element <NUM> with a high recovery rate according to an exemplary embodiment of the present invention.

The reverse osmosis element <NUM> with a high recovery rate includes reverse osmosis membranes <NUM>, a reverse osmosis spacer <NUM> with a high recovery rate, a tricot filtered water channel <NUM>, and a tube <NUM>.

The reverse osmosis element <NUM> with a high recovery rate may be configured such that the reverse osmosis membranes <NUM>, the reverse osmosis spacer <NUM> with a high recovery rate, and the tricot filtered water channel <NUM> are stacked multiple times and surround the tube <NUM>. The reverse osmosis spacer <NUM> with a high recovery rate is positioned between the reverse osmosis membranes <NUM> and maintains a constant interval between the reverse osmosis membranes <NUM>. The reverse osmosis spacer <NUM> may serve to block a surface of the reverse osmosis membrane <NUM> in order to filter out contaminants contained in raw water introduced through the reverse osmosis membrane <NUM>. Therefore, in order to enable contaminants contained in the raw water to flow without being collected, the reverse osmosis spacer <NUM> with a high recovery rate has a mesh shape made by a plurality of strands arranged to have predetermined intersection points. In this case, a material of the strand may be, but not particularly limited to, any one of polyethylene (PE), polyvinyl chloride (PVC), polyester, and polypropylene (PP). The mesh shape has a two-layer structure.

First, some strands are disposed in parallel at predetermined intervals in a direction inclined with respect to a flow direction of raw water. Thereafter, the remaining strands are disposed in parallel at predetermined intervals on the previous strands in a reversely inclined direction symmetrical to the inclined direction in order to form the intersection points. The mesh shape may be a parallelogrammatic shape having identical sides based on positions of the disposed strands. In this case, an angle at one side of the parallelogram with respect to the flow direction of the raw water is <NUM>° to <NUM>°. If the angle of the parallelogram exceeds <NUM>°, flow resistance of the raw water increases, which may cause an increase in differential pressure. In contrast, if the angle of the parallelogram is less than <NUM>°, the interruption of the strands is decreased, such that residual substances, which are produced when the raw water is filtered and produced water is produced, remain at the interface of the reverse osmosis membrane, and as a result, concentration of the raw water at the interface of the reverse osmosis membrane is increased, which may cause a decrease in salt removal rate.

Meanwhile, since the reverse osmosis spacer <NUM> with a high recovery rate has the mesh shape having the parallelogrammatic shape with the identical sides, all of the strands have the same SPI (strand per Inch). The SPI refers to the number of intersection points between the strands included in a length of <NUM> inch. The SPI of the strands is <NUM>. If the SPI is smaller than <NUM>, the ion polarization occurs, such that the raw water may not be mixed, the salt removal rate may be decreased, and a performance of the reverse osmosis element <NUM> may deteriorate. In contrast, if the SPI is larger than <NUM>, there is an effect of inhibiting the ion polarization, but there may be a problem in that a pressure loss is increased in the reverse osmosis spacer <NUM> with a high recovery rate.

In addition, a thickness of the reverse osmosis spacer with a high recovery rate is <NUM> (<NUM> mil). If the thickness is smaller than <NUM> (<NUM> mil), the flow path may be clogged with foreign substances contained in the raw water or power required for a pump for pumping the raw water may be increased. If the thickness is larger than <NUM> (<NUM> mil), the flow path is widened such that the differential pressure may be reduced, but the effect of reducing the ion polarization may deteriorate during the operation under a condition at a high recovery rate.

When the reverse osmosis spacer <NUM> with a high recovery rate satisfies one or more of the thickness of the strand, the angle at one side between the intersection points, and the SPI, the effect of mixing the flows of the raw water is improved, such that the ion polarization may be mitigated.

The tricot filtered water channel <NUM> used according to the present invention generally has a woven fabric structure and serves as a flow path having a space through which water purified by the reverse osmosis membrane <NUM> flows out.

The tube <NUM> according to the present invention is positioned at a center of the reverse osmosis element <NUM> with a high recovery rate and serves as a passageway through which the filtered water is introduced and discharged. To this end, voids (or openings) having predetermined sizes may be formed in an outer portion of the tube <NUM> so that the filtered water is introduced through the voids. In this case, the one or more voids may be formed so that the filtered water may be introduced more efficiently.

The reverse osmosis element <NUM> with a high recovery rate satisfies all of the thickness of the strand of the reverse osmosis spacer <NUM> with a high recovery rate, the angle of one side between the intersection points, and the SPI and operates at raw water concentration of <NUM> ppm, operating pressure of <NUM> psi, and a recovery rate of <NUM>%. If the reverse osmosis element operates at a recovery rate less than <NUM>%, a flow rate of produced water is low. If the reverse osmosis element operates at a recovery rate exceeding <NUM>%, the amount of filtered water is increased, and the ion polarization becomes severe at the interface of the reverse osmosis membrane, such that a rate of removing salt contained in the raw water may be greatly decreased. Therefore, when the reverse osmosis element <NUM> with a high recovery rate operates at the high recovery rate of <NUM> to <NUM>%, a flow rate of produced water may be effectively increased, a salt removal rate may be less decreased, and the amount of discarded water may be reduced.

A reverse osmosis spacer in the related art was prepared in which a thickness of the reverse osmosis spacer with a high recovery rate is <NUM> (<NUM> mil), an angle at one side between intersection points is <NUM>°, and SPI is <NUM>.

A reverse osmosis spacer with a high recovery rate according to the present invention was prepared in which a thickness of the reverse osmosis spacer with a high recovery rate is <NUM> (<NUM> mil) an angle at one side between intersection points is <NUM>°, and SPI is <NUM>.

These values are obtained by measuring the salt removal rate and the flow rate in the reverse osmosis element at the raw water concentration of <NUM> ppm and the operating pressure of <NUM> kPa (<NUM> psi). The reverse osmosis spacers according to the examples and the comparative examples each are formed in a mesh shape. Referring to Tables <NUM> and <NUM>, Comparative Examples <NUM> and <NUM> used the reverse osmosis spacers in the related art, and Example <NUM> used the reverse osmosis spacers with a high recovery rate according to the present invention. First, when comparing Comparative Examples <NUM> and <NUM> and Example <NUM>, the angles at one side between the intersection points between the strands were equally <NUM>°, the SPIs were equally <NUM>, and the thickness of the reverse osmosis spacer with a high recovery rate was <NUM> (<NUM> mil) Comparative Example <NUM>, <NUM> (<NUM> mil) in Comparative Example <NUM>, and <NUM> (<NUM> mil) in Example <NUM>. First, as a result of measuring the salt removal rate at the recovery rate of <NUM>%, the salt removal rate was <NUM>% in Comparative Example <NUM>, <NUM>% in Comparative Example <NUM>, and <NUM>% in Example <NUM>. In addition, as a result of measuring the flow rate at the recovery rate of <NUM>%, the flow rate was <NUM> GFD in Comparative Example <NUM>, <NUM> GFD in Comparative Example <NUM>, and <NUM> GFD in Example <NUM> ( <NUM> GFD=<NUM> LMH (Litre/m2/h)). As a result of measuring the salt removal rate at the high recovery rate of <NUM>%, the salt removal rate was <NUM>% in Comparative Example <NUM>, <NUM>% in Comparative Example <NUM>, and <NUM>% in Example <NUM>. In addition, as a result of measuring the flow rate at the high recovery rate of <NUM>%, the flow rate was <NUM> GFD in Comparative Example <NUM>, <NUM> GFD in Comparative Example <NUM>, and <NUM> GFD in Example <NUM>. ( <NUM> GFD=<NUM> LMH (Litre/m2/h)). In Comparative Example <NUM>, the salt removal rate was decreased by <NUM>% and the flow rate was increased by <NUM> GFD under the condition of the recovery rate of <NUM>% in comparison with the condition of the recovery rate of <NUM>%. In Comparative Example <NUM>, the salt removal rate was decreased by <NUM>% and the flow rate was increased by <NUM> GFD under the condition of the recovery rate of <NUM>% in comparison with the condition of the recovery rate of <NUM>%. In Example <NUM>, the salt removal rate was decreased by <NUM>% and the flow rate was increased by <NUM> GFD under the condition of the recovery rate of <NUM>% in comparison with the condition of the recovery rate of <NUM>%. Therefore, it can be ascertained that as the thickness (mil) of the reverse osmosis spacer with a high recovery rate becomes smaller, the flow rate of the produced water in the reverse osmosis element may be further increased and the salt removal rate may be less decreased, compared to the related art, when the reverse osmosis element operates at the high recovery rate.

In the case of Example <NUM>, the thickness of the reverse osmosis spacer with a high recovery rate was <NUM> (<NUM> mil) the angle at one side between the intersection points was <NUM>°, and the SPI was <NUM>. First, as a result of measuring the salt removal rate at the recovery rate of <NUM>%, the salt removal rate was <NUM>%, and the flow rate was <NUM> GFD. In contrast, as a result of measuring the salt removal rate at the high recovery rate of <NUM>%, the salt removal rate was <NUM>%, and the flow rate was <NUM> GFD. Therefore, in Example <NUM>, the salt removal rate was decreased by <NUM>% and the flow rate was increased by <NUM> GFD under the condition of the recovery rate of <NUM>% in comparison with the condition of the recovery rate of <NUM>%. Therefore, it can be ascertained that when the angle at one side between the intersection points between the strands is decreased and the SPI of the strands is increased even though the thickness of the strand is increased, the flow rate of the produced water in the reverse osmosis element may be increased, and the salt removal rate may be less decreased, compared to the related art, like Example <NUM>.

Claim 1:
Use of a reverse osmosis element (<NUM>) with a high recovery rate for salt removal,
the reverse osmosis element (<NUM>) comprising
- a reverse osmosis spacer (<NUM>) with a high recovery rate;
- a tube (<NUM>) comprising an opening configured to receive a permeable liquid in a longitudinal direction;
- one or more reverse osmosis membranes (<NUM>) wound around the tube (<NUM>) and extending outward from the tube (<NUM>) and
- the reverse osmosis spacer (<NUM>) wound around the tube and being in contact with the one or more reverse osmosis membranes (<NUM>) ;
wherein the reverse osmosis spacer (<NUM>) has a mesh shape having a plurality of strands having predetermined intersection points and forming a mesh having a two-layer structure and operates at a recovery rate of <NUM>;
a thickness of the reverse osmosis spacer (<NUM>) is <NUM> (<NUM> mil) ;
an angle at one side between the intersection points between the strands is <NUM>°;
the SPI (strand per Inch) of the strands is <NUM>,
corresponding to <NUM> strands per cm;
the reverse osmosis element (<NUM>) operates at pressure of <NUM> kPa (<NUM> psi);
wherein the reverse osmosis element (<NUM>) operates at a raw water concentration of <NUM> ppm, which is the concentration of both salt and contaminants in the raw water.