JP2009195871A - Spiral membane element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spiral membrane element which can moderate the gradient of permeation efficiency in the radial direction and thereby, minimize the dispersion of separation performance. <P>SOLUTION: This spiral membrane element is of such a structure that a separation membrane (14), a supply-side flow path material (11) and a permeation-side flow path material (13) are singly or plurally wound around a porous hollow center pipe (12). In addition, the permeation-side flow path material (13) is characteristic in that the material (13) becomes gradually thicker from the outer circumferential side end part (13a) to the inner circumferential side end part (13b). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spiral membrane element that separates components suspended and dissolved in a liquid.

  As a structure of a conventional spiral membrane element (hereinafter also simply referred to as “membrane element”), one or more of a separation membrane, a supply-side channel material, and a permeate-side channel material are perforated hollow center tubes ( Hereafter, what is simply wound around the "center tube" is known (see, for example, Patent Document 1).

  FIG. 3 is a partially cutaway perspective view of a conventional membrane element. The membrane element 1 shown in this figure has a structure in which a separation membrane unit including a separation membrane 2, a supply-side channel material 6 and a permeation-side channel material 3 is wound around a central tube 5. More specifically, an envelope-like membrane (bag-like membrane) 4 is formed by overlapping the separation membrane 2 on both sides of the permeate-side flow path material 3 and adhering three sides, and the opening of the envelope-like membrane 4 Is attached to the central tube 5 and wound around the outer peripheral surface of the central tube 5 together with a net-like (net-like) supply-side flow path member 6 in a spiral shape.

  When the membrane element 1 is used, the supply liquid 7 is supplied from one end face side of the membrane element 1. The supplied supply liquid 7 flows along the supply-side flow path member 6 in a direction parallel to the axial direction of the central tube 5 and is discharged as a concentrated liquid 9 from the other end face side of the membrane element 1. Further, the permeated liquid 8 that has permeated through the separation membrane 2 in the process in which the supply liquid 7 flows along the supply-side flow path material 6 passes through the permeation-side flow path material 3 along the permeation-side flow path material 3 as shown by the broken line arrow in the figure. It flows into the interior and is discharged from the end of the central tube 5.

  In the conventional membrane element 1, when the permeate 8 flows into the center tube 5, the flow rate of the permeate 8 increases toward the center tube 5, so that the permeate 8 flows from the outer periphery side to the inner periphery side. A phenomenon occurs in which the road resistance increases. As a result, the separation efficiency may vary due to the gradient of the permeation efficiency in the radial direction of the membrane element 1.

On the other hand, with an increase in the size of the membrane processing plant, it is desired to reduce the installation area of the membrane separation apparatus. In the past, the mainstream was to use a membrane element with a diameter of 8 inches (about 200 mm). However, due to the above demand, reduction of the number of membrane elements has been demanded. Measures to increase the per unit film area are underway.
Japanese Patent Laid-Open No. 10-137558

  However, when the diameter of the membrane element is increased, variation in separation performance may become apparent due to the gradient of permeation efficiency in the radial direction.

  An object of the present invention is to provide a spiral-type membrane element that can alleviate the gradient of the transmission efficiency in the radial direction and reduce the variation in separation performance.

  As a result of intensive research, the present inventors have gradually increased the thickness of the permeate channel from the outer periphery side to the inner periphery side of the permeate side channel material, so that the flow on the inner periphery side of the permeate side channel material is increased. It has been found that an increase in road resistance can be suppressed, and the present invention has been completed.

  In order to achieve the above object, the first spiral membrane element of the present invention includes a separation membrane, a supply side channel material and a permeation side channel material wound around a perforated hollow central tube. In the attached spiral membrane element, the thickness of the permeate-side channel material gradually increases from the outer peripheral side end portion to the inner peripheral side end portion. In addition, the thickness of the edge part of the permeation | transmission side channel material means the thickness of the bulky part in the said edge part. For example, when the permeate-side channel material is a net-like sheet composed of warp and weft, the thickness of the end of the permeate-side channel material refers to the thickness of the intersection of the warp and weft at the end. The same applies to “the thickness of the end of the supply-side channel material” and “the thickness of the channel material sheet” which will be described later.

  In the first spiral membrane element of the present invention, since the thickness gradually increases from the outer peripheral side end of the permeate side channel material to the inner peripheral side end of the permeate side channel material, the outer peripheral side to the inner peripheral side , The thickness of the permeate channel can be gradually increased. Thereby, since the increase in the channel resistance on the inner peripheral side of the permeation side channel material can be suppressed, the gradient of the permeation efficiency in the radial direction of the membrane element can be relaxed, and the variation in separation performance can be reduced.

  The permeate side channel material preferably has an increase in thickness per unit length in the permeate flow direction of 0.023 mm / m or more. This is because an increase in channel resistance on the inner peripheral side of the permeate-side channel material can be easily suppressed.

  Similarly, in order to achieve the above object, the second spiral membrane element of the present invention includes a separation membrane, a supply-side flow channel material, and a permeation-side flow channel material around a perforated hollow central tube. In the spiral wound membrane element, the permeate-side channel material is a laminate in which a plurality of channel material sheets are laminated, and the laminate is arranged from the outer peripheral end to the inner peripheral end. The number of laminations of the flow path material sheets gradually increases.

  In the second spiral membrane element of the present invention, the number of laminations of the flow path material sheets constituting the permeate side flow path material is gradually increased from the outer peripheral side end of the laminated body to the inner peripheral side end of the laminated body. Therefore, the thickness of the permeate channel can be gradually increased from the outer peripheral side to the inner peripheral side. Thereby, since the increase in the channel resistance on the inner peripheral side of the permeation side channel material can be suppressed, the gradient of the permeation efficiency in the radial direction of the membrane element can be relaxed, and the variation in separation performance can be reduced.

  The laminated body preferably has an increase in the number of laminated layers per unit length in the permeate flow direction of 0.33 sheets / m or more. This is because an increase in channel resistance on the inner peripheral side of the permeate-side channel material can be easily suppressed.

  In the first and second spiral membrane elements, it is preferable that the supply-side channel material gradually decreases in thickness from the outer peripheral side end portion to the inner peripheral side end portion. According to this configuration, the separation membrane unit can be easily wound, and the amount of the supply liquid that flows from the supply-side channel material to the separation membrane from the outer peripheral side end to the inner peripheral side end of the supply-side channel material Therefore, an increase in the amount of permeated liquid can be suppressed on the inner peripheral side of the permeate-side channel material. Thereby, the increase in the channel resistance in the inner peripheral side of the permeation | transmission side channel material can be suppressed easily.

  The spiral membrane element of the present invention has a structure in which one or more of a separation membrane, a supply-side channel material and a permeation-side channel material are wound around a perforated central tube. Such a membrane element is also described in detail in Patent Document 1 described above, and regarding the configuration other than the permeation side channel material, any conventionally known separation membrane, supply side channel material, center tube, etc. can be adopted. . For example, when a plurality of supply-side channel materials and permeation-side channel materials are used, a structure in which a plurality of membrane leaves are wound around the central tube is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG.1 and FIG.2 is a typical schematic side view for demonstrating an example of the spiral membrane element of this invention, respectively. 1 and FIG. 2 show a state in which the winding of the separation membrane unit is unwound from the central tube for easy explanation, and there are parts shown enlarged or reduced. For ease of explanation, FIGS. 1 and 2 show only one set of separation membrane units. However, the spiral membrane element of the present invention is centered in a state where a plurality of separation membrane units are stacked. It may be wound around a tube.

  In the embodiment shown in FIG. 1, the separation membrane unit U includes an envelope membrane 10 and a supply-side channel material 11, and the opening 10 a of the envelope membrane 10 is attached to the central tube 12. A membrane element is formed by winding it around the outer peripheral surface of the center tube 12 together with the supply-side channel material 11. The envelope-like membrane 10 is formed by superposing the separation membranes 14 on both sides of the permeate-side channel material 13 and bonding the three sides excluding the opening 10a. In the present embodiment, the permeate that has permeated through the separation membrane 14 passes through the permeate-side flow path member 13 along the permeate flow direction 15 and flows into the center tube 12.

  And the permeation | transmission side channel material 13 is increasing gradually from the outer peripheral side edge part 13a to the inner peripheral side edge part 13b. Thereby, since the thickness of the permeate flow path can be gradually increased from the outer peripheral side to the inner peripheral side, an increase in flow path resistance on the inner peripheral side of the permeate side flow path member 13 can be suppressed. Therefore, the gradient of the transmission efficiency in the radial direction of the membrane element can be relaxed, and the variation in separation performance can be reduced. In particular, when the present invention is applied to a membrane element having a large diameter (for example, 16 inches or more in diameter), variation in separation performance can be effectively prevented as compared with the case of using a conventional permeation side channel material.

  The supply-side channel material 11 can be a net-like sheet such as a rhombus, ladder, or diagonal ladder, or a sheet with a grooved structure or a corrugated structure. The center tube 12 only needs to have an opening 12a around the tube, and any conventional tube can be used. For the permeate-side channel material 13, a net-like sheet such as tricot knitting, a mesh-like sheet such as plain weave, or a sheet having a grooved structure or a corrugated structure can be used. As the separation membrane 14, a reverse osmosis membrane, an ultrafiltration membrane, a microfiltration membrane, or the like can be used.

The difference between the thickness T ₁ of the inner circumferential end 13b of the thickness T ₂ and the outer end portion 13a as long as the increase in flow path resistance in the inner peripheral side of the permeation-side passage material 13 can be suppressed is not particularly limited. These may be appropriately set according to the diameter of the membrane element, the number of stacked separation membrane units U, and the like. The method of changing the thickness is not particularly limited. For example, when a net-like sheet is used as the permeate-side flow path member 13, the diameter of the net-constituting yarn is gradually increased from the outer peripheral end 13a to the inner peripheral end 13b. Just do it. In this case, it is not necessary to gradually increase the diameters of all the net constituent yarns. For example, only the net constituent yarns arranged along the permeate flow direction 15 need only be increased gradually.

In order to easily suppress an increase in flow path resistance on the inner peripheral side of the permeate side flow path material 13, the amount of increase in thickness per unit length in the permeate flow direction 15 is 0.023 mm / m or more. Is preferable, and it is more preferable that it is 0.07 mm / m or more. Here, the value of the "amount of increase in thickness" refers to the difference between the thickness T ₁ of the inner circumferential side thickness T ₂ of the end 13b _(mm) and the outer edge portion 13a _(mm), permeation-side passage material 13 divided by the length L ₁ (m) in the permeate flow direction 15. Further, in order to facilitate winding of the separation membrane unit U, the increase in the thickness is preferably 2.5 mm / m or less, and more preferably 1.7 mm / m or less. The thickness _{T 1} of the outer end portion 13a of the permeation-side passage material 13, for example, about 0.2 to 0.3 mm, the thickness _{T 2} of the inner circumferential end 13b of the permeation-side passage material 13 For example, it is about 0.5 to 1.0 mm. These thickness values are preferably average values obtained by measuring at least 10 points. As the measuring method, a method of measuring with a thickness measuring instrument such as a dial thickness gauge or an enlargement device such as an optical microscope or a CCD camera is preferable. The same applies to “the thickness of the end portion of the supply-side channel material” and “the thickness of the channel material sheet” which will be described later. Further, the length _{L 1} is, for example, about 0.5-3 m.

  The supply-side channel material 11 has a thickness that gradually decreases from the outer peripheral end 11a to the inner peripheral end 11b. As a result, the separation membrane unit U can be easily wound, and the supply flowing from the supply-side channel material 11 to the separation membrane 14 from the outer peripheral side end 11a to the inner peripheral side end 11b of the supply-side flow channel material 11. Since the amount of the liquid decreases, an increase in the amount of the permeated liquid can be suppressed on the inner peripheral side of the permeate-side flow path member 13. Therefore, an increase in channel resistance on the inner peripheral side of the transmission side channel material 13 can be easily suppressed. The amount of decrease in the thickness of the supply side channel material 11 may be set in accordance with the amount of increase in the thickness of the permeation side channel material 13, but from the viewpoint of facilitating winding of the separation membrane unit U, the separation membrane unit. It is preferable to set the thickness of U to be substantially constant. The method of changing the thickness of the supply-side channel material 11 is not particularly limited. For example, when a net-like sheet is used as the supply-side channel material 11, the net is extended from the outer peripheral side end portion 11a to the inner peripheral side end portion 11b. What is necessary is just to reduce the diameter of a constituent yarn gradually. In this case, it is not necessary to gradually reduce the diameters of all the net constituent yarns. For example, only the net constituent yarns arranged along the supply liquid flow direction may be gradually reduced. In addition, the thickness of the outer peripheral side edge part 11a of the supply side flow path material 11 is about 1.0-5.0 mm, for example, and the thickness of the inner peripheral side edge part 11b of the supply side flow path material 11 is, for example, 0.00. It is about 6 to 0.9 mm.

  Next, the embodiment shown in FIG. 2 will be described. In this embodiment, only the configuration of the permeate-side channel material 13 is different from the embodiment shown in FIG. 1 described above. The permeation-side channel material 13 of the present embodiment is a laminate 20 in which channel material sheets 20a, 20b, and 20c are sequentially laminated from below in the drawing. The channel material sheets 20 a, 20 b, and 20 c are attached to the central tube 12 at their inner peripheral side ends. The lengths of the flow path material sheets 20a, 20b, and 20c in the permeate flow direction 15 are different. Specifically, the length of the flow path material sheet 20b is half of the length of the flow path material sheet 20a, and the length of the flow path material sheet 20c is half of the length of the flow path material sheet 20b. . Therefore, in the laminated body 20, the number of laminated flow path material sheets gradually increases from the outer peripheral end 20d to the inner peripheral end 20e. Thereby, since the thickness of the permeate flow path can be gradually increased from the outer peripheral side to the inner peripheral side, an increase in flow path resistance on the inner peripheral side of the laminate 20 (permeate side flow path material 13) can be suppressed. Therefore, the gradient of the transmission efficiency in the radial direction of the membrane element can be relaxed, and the variation in separation performance can be reduced.

  A net-like sheet, a mesh-like sheet, a grooved sheet, a corrugated sheet, or the like can be used for the flow path material sheets 20a, 20b, and 20c. In addition, the thickness of the flow path material sheets 20a, 20b, and 20c is, for example, about 0.2 to 0.6 mm.

  In the present embodiment, the difference between the number of the flow path material sheets laminated at the inner peripheral side end 20e and the number of the flow path material sheets laminated at the outer peripheral end 20d is two, but the transmission side flow path material 13 The difference is not particularly limited as long as an increase in flow resistance on the inner peripheral side of the tube can be suppressed. These may be appropriately set according to the diameter of the membrane element, the number of stacked separation membrane units U, and the like.

In order to easily suppress an increase in flow resistance on the inner peripheral side of the laminate 20 (permeation side flow path material 13), an increase amount of the number of flow path material sheets stacked per unit length in the permeate flow direction 15 However, it is preferably 0.33 sheet / m or more, and more preferably 1 sheet / m or more. Here, the value of the “increase in the number of stacked layers” is the difference between the number of stacked layers at the inner peripheral side end 20e and the number of stacked layers at the outer peripheral side end 20d (two in FIG. 2). It is a value divided by the length L ₂ (m) in the permeate flow direction 15 of the side channel material 13). In order to facilitate winding of the separation membrane unit U, the increase in the number of stacked layers is preferably 8 sheets / m or less, and more preferably 3 sheets / m or less. Incidentally, the length _{L 2} is, for example, about 0.5-3 m.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the supply-side channel material whose thickness gradually decreases from the outer peripheral side end to the inner peripheral side end is used. However, in the present invention, the supply-side channel material is used with a uniform thickness. However, it is possible to suppress an increase in flow resistance on the inner peripheral side of the permeation side flow path material.

  Further, in the embodiment shown in FIG. 1, the example in which the thickness continuously increases from the outer peripheral side end to the inner peripheral side end as the permeate side channel material has been described, but in the present invention, from the outer peripheral side end. You may use the permeation | transmission side flow path material which thickness becomes thick intermittently toward an inner peripheral side edge part.

  Further, in the embodiment shown in FIG. 2, the example in which the number of laminations of the flow path material sheets increases at a predetermined interval from the outer peripheral side end to the inner peripheral side end of the laminated body has been described. You may use the permeation | transmission side flow path material in which the number of lamination | stacking increases at irregular intervals from an outer peripheral side edge part to an inner peripheral side edge part.

It is a typical schematic side view for demonstrating an example of the spiral type membrane element of this invention. It is a typical schematic side view for demonstrating another example of the spiral type membrane element of this invention. It is a partially cutaway perspective view of a conventional membrane element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Envelope-like film | membrane 10a Opening part 11 Supply side flow path material 11a Outer peripheral side edge part 11b Inner peripheral side edge part 12 Center pipe 12a Opening hole 13 Permeation side flow path material 13a Outer peripheral side edge part 13b Inner peripheral side edge part 14 15 Permeate flow direction 20 Laminate 20a, 20b, 20c Channel material sheet 20d Outer peripheral end 20e Inner peripheral end U Separation membrane unit

Claims (5)

In the spiral membrane element in which one or more of the separation membrane, the supply-side channel material and the permeation-side channel material are wound around a perforated hollow central tube,
The spiral-type membrane element characterized in that the permeation-side flow path material gradually increases in thickness from an outer peripheral side end to an inner peripheral side end.   2. The spiral membrane element according to claim 1, wherein the permeate-side channel material has an increase in thickness per unit length in the permeate flow direction of 0.023 mm / m or more. In the spiral membrane element in which one or more of the separation membrane, the supply-side channel material and the permeation-side channel material are wound around a perforated hollow central tube,
The permeate-side channel material is a laminate in which a plurality of channel material sheets are laminated,
The spirally-type membrane element, wherein the number of layers of the flow path material sheets gradually increases from the outer peripheral side end portion to the inner peripheral side end portion.   4. The spiral membrane element according to claim 3, wherein the laminate has an increase in the number of layers per unit length in the permeate flow direction of 0.33 sheets / m or more.   The spiral-type membrane element according to any one of claims 1 to 4, wherein the supply-side channel material gradually decreases in thickness from an outer peripheral side end portion to an inner peripheral side end portion.

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