JP2002191944A - Fluid separating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid separating element by which ordinary fluid separation can be performed in a short time after operation is started even in a case where an original water with a low TOC concentration is treated such as a field for manufacturing ultrapure water and with a slight self-eluation of organic carbon. SOLUTION: The fluid separating element with a membrane unit containing a feed liquid flow path material, a separating membrane and a transmitted liquid flow path material around a water collecting pipe is such a fluid separating element in which after a water with a TOC concentration of 1-3 ppb and a temperature of 50 deg.C is washed by transmitting it through for 1 hour by a membrane transmitting flux density of 0.3 m3/m2/day, when a water in a range of a TOC concentration of 1-3 ppb and at a temperature of 25 deg.C is treated by a membrane transmitting flux density of 1.0 m3/m2/day, a relation between the TOC concentration (TOCin) of the original water after 3 hours passes from starting of the treatment and the TOC concentration (TOCout) of the transmitted water is TOCout-TOCin<=2 ppb.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid separation element suitably used for producing ultrapure water, and more particularly, to a fluid separation element with less elution of organic carbon.

[0002]

2. Description of the Related Art As a fluid separation element using a separation membrane such as a reverse osmosis membrane, there are a spiral type, a plate and frame type, and a hollow type fluid separation element. For example,
A spiral-type fluid separation element 1 using a reverse osmosis membrane shown in FIG. 1 which is most frequently used because a large number of membranes can be provided in a fixed volume sandwiches a permeated liquid flow path material 2. Thus, the separation membrane 3 is folded in two, and the two ends 11 of the separation membrane in the axial direction of the water collecting pipe are sealed with an adhesive to form an envelope-shaped membrane 4, and the envelope-shaped membrane 4 is opened on the water collecting pipe 5 side. In such a manner as to overlap the supply liquid flow path material 6 and spirally surround the water collecting pipe 5.

In the fluid separation element 1, a supply liquid 7 is supplied from one end of the fluid separation element 1, and a part of the supply liquid 7 passes through the separation membrane 3 while flowing along the supply liquid flow path member 6. The permeated liquid 9 that has passed through the separation membrane 3 passes through the water collecting hole 10 of the water collecting pipe 5 along the permeated liquid flow path material 2 and is discharged to the end of the water collecting pipe 5. The remainder of the supply liquid 7 that has not passed through the separation membrane 3 is transferred from the other end face of the fluid separation element 1 to the concentrated liquid 8.
Is discharged as At this time, the supply liquid 7 passes through the separation membrane 3 to remove organic carbon in the treated water, and the permeated water having a low organic carbon concentration (hereinafter referred to as TOC concentration) is used as pure water or ultrapure water. .

As described above, in order to make the treated water pure water or ultrapure water, organic carbon in the treated water is eliminated by using a fluid separating element. However, the fluid separating element usually removes impurities at the final stage of the manufacturing process. Despite the flushing, organic carbon is self-eluted from the adhesive or separation membrane used for the fluid separation element itself, so the permeated water immediately after the start of operation contains more organic carbon than is contained in the raw water Have been. Therefore, the operation is continued as it is to reduce the TOC concentration.
When the concentration is low, it often takes 24 hours or more for the TOC concentration of the permeated water to become lower than the raw water,
In some cases, several days may be required, and during that time the treated water and time must be wasted.
No. 0259 discloses that a fluid separation element and a membrane are made of an acidic solution or an alkaline solution in order to prevent the organic carbon contained in the raw water as much as possible and to reduce the TOC concentration in the permeated water immediately after the start of operation to a certain level or less in a short time. A method for washing with a solution is disclosed. Also, Japanese Patent Application Laid-Open No. 7-802
Japanese Unexamined Patent Publication No. 60-80261 discloses a method for cleaning a fluid separation element and a membrane with hot pure water, and Japanese Patent Laid-Open No. 7-80261 discloses a method for cleaning a fluid separation element and a membrane with a chlorine-containing aqueous solution. JP-A-7-80262 describes a method of cleaning a fluid separation element and a membrane with an organic solvent. However, in any of the methods described in these documents, a sufficient effect is obtained when the TOC concentration of the supply water is as high as 10 to 30 ppb, but the TOC concentration of the supply water is 1 to 3 ppb.
If it is as low as ppb, it will be insufficient.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for self-elution of organic carbon which can perform normal fluid separation in a short time after starting operation even when treating raw water having a low TOC concentration, such as in the field of ultrapure water production. It is an object of the present invention to provide a small fluid separation element.

[0006]

In order to achieve the above object, according to the present invention, a membrane unit including a supply liquid flow path material, a separation membrane, and a permeate liquid flow path material is formed around a water collecting pipe. The fluid separation element comprising:
The method is characterized by a method of manufacturing a fluid separation element for supplying and cleaning at a flow rate of 5 m ³ / m ² · day or more. At this time, it is preferable to wash by supplying water pressurized at a pressure of 0.05 to 0.6 MPa for a period of 1 to 20 hours.

[0007] Further, the present invention provides a method for supplying a supply liquid around a collecting pipe.
Membrane unit including flow path material, separation membrane, and permeate flow path material
And water at 40 to 90 ° C. is supplied at a membrane permeation flow rate of 0.0
5m ^Three/ M^Two・ Supply and clean so that it is more than day
Characterized by a fluid separation element. Where the pressure
Water pressurized in the range of 0.05-0.6 MPa
It must be supplied and cleaned within 0 hours.
preferable.

Further, the present invention is a fluid separation element having a membrane unit including a supply liquid flow path material, a separation membrane, and a permeate flow path material around a water collecting pipe, wherein the TOC concentration is 1 to 3 p.
pb water at a temperature of 50 ° C. with a membrane permeation flux of 0.3 m ³ / m ² / d
ay for 15 hours, and then washed with a TOC concentration of 1 to
Water at 25 ° C. in the range of 3 ppb is passed through
^When treated at ³ / m ² · d, the TOC concentration of raw water (TOC _in ) and the permeated water TOC at 3 hours after the start of treatment
The relationship with the concentration (TOC _out ) is: TOC _out −TOC _in ≦
It features a fluid separation element at 2 ppb.

Here, the fluid separation element of the present invention is treated with water at 25 ° C. having a TOC concentration in the range of 1 to 3 ppb immediately after washing, or stored for one month after washing, and thereafter,
In the case of treating water at 25 ° C. having a TOC concentration of 1 to 3 ppb, it is preferable that the difference in the permeated water TOC concentration after 3 hours from the start of the treatment is within 5 ppb. Further, the separation membrane is preferably formed in an envelope shape with an adhesive containing trifunctional butadiene diol,
More preferably, the adhesive contains isocyanate as a main component and trifunctional butadiene diol as a curing agent.

The above-described fluid separation element is suitable for producing ultrapure water, and a fluid separation membrane module in which such a fluid separation element is housed in a pressure vessel is also a preferred embodiment.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluid separation element according to the present invention will be described with reference to FIG.

The fluid separation element 1 of the present invention includes a supply liquid flow path member 6 and an envelope-shaped membrane 4 formed so that a permeate liquid flow path member 2 is sandwiched between separation membranes 3 around a water collecting pipe 5. The membrane unit is wound, for example, in a spiral shape. The envelope-shaped membrane 4 folds the separation membrane 3 so as to sandwich the permeated liquid flow path material 2, and divides the overlapping separation membranes 3 into two sides adjacent to the center side of the fold (when wound around the water collection pipe 5). At both ends 11) in the axial direction.

[0013] Such a fluid separation element 1 is used after being washed since the permeated water TOC concentration in the initial stage of operation becomes extremely high. By performing this cleaning at a higher temperature and increasing the amount of permeated water, the cleaning effect is increased.On the contrary, the temperature can be made close to room temperature, and the amount of permeated water can be reduced to reduce the cleaning cost and production cost. In the present invention, in particular, in order to clean the self-eluting organic carbon used from the adhesive and the separation membrane 3 used, and to satisfy a good balance between the cleaning effect and the cost, warm water of 40 to 90 ° C. is used. It is supplied and washed so that the permeation flow rate becomes 0.05 m ³ / m ² · day or more. In particular, by passing hot water of this degree at the above-mentioned membrane permeation flow rate, the diffusion effect of organic carbon is improved, so that the organic carbon in the separation membrane 3 is effectively eluted and a part of the permeated warm water is permeated. The organic carbon eluted from the adhesive itself can be efficiently washed away by flowing through the adhesive end face facing the liquid flow path material 2. When the softening temperature in water is 7
When using polyester or the like at about 0 ° C., the temperature of the washing water is preferably adjusted to 50 to 70 ° C.

In addition, the longer the cleaning time, the greater the cleaning effect. On the contrary, the shorter the cleaning time, the more the cleaning cost and the manufacturing cost can be reduced. It is preferable to wash by supplying pressurized water for 1 to 20 hours.

Further, the fluid separation element usually undergoes storage, transportation, etc. before it is used in a plant or the like. During storage or transportation, organic carbon contained in an adhesive or the like passes through a permeate flow path or a supply path. The organic carbon is moved to a portion that has already been washed, such as a liquid channel, and the organic carbon is included in the permeated water after the start of the treatment, and the TOC concentration of the permeated water increases. For this reason, when the raw water having a TOC concentration in the range of 1 to 3 ppb is used as the fluid separation element, the TOC concentration of the permeated water in the initial stage of operation becomes much higher than the TOC concentration of the raw water.

However, the fluid separation element 1 of the present invention
Permeates water at a temperature of 50 ° C with a TOC concentration of 1 to 3 ppb
0.3m flux^Three/ M^Two/ Day for 1 hour to wash
After that, the water at 25 ° C. having a TOC concentration of 1 to 3 ppb was used.
Is 1.0 m^Three/ M^Two・ When processing with d, processing is opened
The TOC concentration of raw water 3 hours after the beginning (TOC concentration)
_in) And TOC concentration of permeate (TOC)_out) Is T
OC_out-TOC_in≤ 2 ppb.

In order to reduce TOC _out -TOC _in to 2 ppb or less, for example, an adhesive containing a trifunctional butadiene diol in an adhesive, particularly an adhesive containing a isocyanate as a main component and a butadiene diol as a curing agent in a trifunctional group Such,
It is preferable to use one that can reduce unreacted monomers of the main agent and the curing agent. By having three functional groups, the remaining unreacted substances are less and the reaction proceeds more sterically than in the case of bifunctional groups, so that a hardened state of a structure in which unreacted substances are harder to elute is formed. As a result, the elution of organic carbon into permeated water can be reduced.

Thus, TOC _out -TOC _in is 2p
If the pressure is not more than pb, since the load at the time of decomposing organic carbon by an ultraviolet irradiation device or the like, which is installed in a subsequent process, does not become excessive, the time required for startup at the start of operation and the amount of water are greatly reduced. It becomes possible to reduce.

Further, although the fluid separation element is often used after one month or more from its manufacture, after the above-mentioned washing, it is stored in a bag sealed under reduced pressure and stored in a cold storage room at about 4 ° C. Water treatment immediately after washing by storing at a temperature up to about 30 ° C, which is the air temperature, or keeping in a state where air permeability is maintained, or when water is treated after storing for one month after washing And the difference in TOC concentration of the permeated water can be reduced. Specifically, the permeated water TOC obtained by treating water at 25 ° C. having a TOC concentration of 1 to 3 ppb for 3 hours.
The concentration difference can be made within 5 ppb, and further within 2 ppb.

By making the difference in the concentration of the permeated water TOC before and after storage within the above range, the load of decomposing organic carbon in a subsequent process such as an ultraviolet irradiation device can be further reduced, and water can be passed immediately after the start of operation in many cases. Also, even if water cannot be passed, the subsequent cleaning time can be shortened,
It is possible to further reduce the time and the amount of water required for startup at the start of operation.

Further, in order to further reduce the time required for passing water, a material having a small amount of self-elution of organic carbon may be used for components such as the supply liquid flow path member 6 and the permeate liquid flow path member 2. preferable. For example, the feed liquid flow path material 6 is fixed by heat fusion of a net made of a polyolefin resin such as polyethylene or polypropylene, and the permeate flow flow path material 2 is a knitted fabric woven from a polyester resin or polyolefin resin called tricot by heat fusion. And the like are preferred.

Further, in order to reduce the TOC concentration of the permeated water, it is preferable that the organic carbon exclusion rate of the separation membrane itself is high, for example, 93 to 95% or more.

If the fluid separation element of the present invention described above is housed in a pressure vessel or the like and modularized, for example, in the case of ultrapure water production in a semiconductor production process or the like, even if the fluid separation element is periodically replaced, After starting operation, high quality water can be obtained in a short time. As a result, in some cases, it is not necessary to stop the semiconductor manufacturing process simply by using ultrapure water obtained from another system or by temporarily increasing the intake load of the ultrapure water production equipment of another system. In many cases, even when the vehicle stops, the time can be greatly reduced.

[0024]

EXAMPLE 1 An operating pressure of 1.5 MPa was used using a fluid separation membrane module containing one fluid separation element of the present invention shown in FIG. 1 in a pressure vessel.
a, membrane permeation flux: 1.0 m ³ / m ² · day, recovery rate: 50
% And a temperature of 25 ° C., water having a TOC concentration of 1.5 ppb was treated, and the TOC concentration of the permeated water was measured.

The fluid separation element has a diameter of 200 mm,
The length was 1 m, and the packed film area was 39 m ² . The fluid separation membrane module has a TOC concentration of 1.5 ppb,
Water was washed at a temperature of 50 ° C. for 1 hour at a pressure of 0.5 MPa so as to have a membrane permeation flux of 0.3 m ³ / m ² / day.

As an adhesive, isocyanate is used as a main component,
A polyurethane adhesive containing butadiene diol having three functional groups was used as a curing agent.

The results are shown in Table 1. The permeate TOC concentration 3 hours after the start of the treatment was as low as 1.5 ppb.

After the washing under the above conditions, the fluid separation element is sealed in a storage bag and stored at 25 ° C. in a dark place for one month.
Thereafter, the operating pressure was 1.5 MPa, and the membrane permeation flux was 1.0 m ^3.
Under the conditions of / m ² · day, a recovery rate of 50%, and a temperature of 25 ° C., water having a TOC concentration of 1.5 ppb was treated, and the TOC concentration of the permeated water was measured. As a result, the TOC concentration was 3.4 ppb, and the TOC concentration change due to storage was 1.9 pb.
It was as small as pb, and the time required for startup was very short. Comparative Example 1 Example 1 was repeated except that the hot water was kept flowing for 20 hours at a pressure at which a membrane permeation flux was not obtained.
The TOC concentration of the permeated water was measured in the same manner as described above.

The results are shown in Table 1. Compared with Example 1, the TOC concentration immediately after washing was higher, and the T
The increase in OC concentration is also large. Comparative Example 2 The TOC concentration of the permeated water was measured in the same manner as in Example 1 except that no hot water washing was performed.

The results are shown in Table 1. Since no washing is performed, the TOC concentration of the permeated water is very high.

[0031]

[Table 1]

[0032]

According to the present invention, the fluid separation element is provided with 40
-90 ° C. water permeation flow rate of 0.05 m ³ / m ² · day
By supplying and cleaning as described above, in particular, it is possible to effectively clean the self-eluting organic carbon which is used from the adhesive and the separation membrane 3 used, and to satisfy the cleaning effect and the cost in a well-balanced manner. it can.

Further, the fluid separation element of the present invention is provided with a water having a TOC concentration of 1 to 3 ppb at a temperature of 50 ° C. and a membrane permeation flux of 0.3 m
After washing by permeation for 1 hour at ³ / m ² / day, TOC
When water at 25 ° C. having a concentration in the range of 1 to 3 ppb is treated at a membrane permeation flow rate of 1.0 m ³ / m ² · d, the TOC concentration (TOC _in ) of the raw water and the permeated water after 3 hours from the start of the treatment The relationship with the TOC concentration (TOC _out ) is TOC _out -T
Since OC _in ≦ 2 ppb, the load at the time of decomposing the organic carbon by the ultraviolet irradiation device or the like installed in the subsequent process does not become excessive, and high-quality water capable of passing water to the subsequent process in a short time. Therefore, the time required for starting up and the amount of waste water can be greatly reduced. As a result, it can be suitably used as a fluid separation element for producing ultrapure water used in a semiconductor production process or the like where growth is remarkable.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a spiral type fluid separation element.

[Explanation of symbols]

 1: fluid separation element 2: permeate flow path material 3: separation membrane 4: envelope-shaped membrane 5: water collecting pipe 6: supply liquid flow path material 7: supply liquid 8: concentrated liquid 9: permeate 10: water collection hole 11 : Both ends of water collecting pipe in the axial direction 12: Filament winding

Claims (10)

[Claims] 1. A feed liquid flow path material and a separation membrane around a water collecting pipe.
And a flow formed by forming a membrane unit including
The body separation element was prepared by passing water at 40 to 90 ° C. at a membrane permeation flow rate of 0.0
5m ^Three/ M^Two・ Supply and clean so that it is at least day
A method for manufacturing a fluid separation element, comprising: 2. The method for producing a fluid separation element according to claim 1, wherein water pressurized at a pressure of 0.05 to 0.6 MPa is supplied for washing for 1 to 20 hours. 3. A membrane unit including a supply liquid flow path material, a separation membrane, and a permeate flow path material around a water collecting pipe, and
The membrane permeation flow rate of water of 0 to 90 ° C is 0.05 m ³ / m ² · da.
A fluid separation element characterized by being supplied and washed so as to be y or more. 4. Washing by supplying water pressurized at a pressure of 0.05 to 0.6 MPa for a period of 1 to 20 hours.
The fluid separation element according to claim 3. 5. A fluid separation element having a membrane unit including a supply liquid flow path material, a separation membrane, and a permeate flow path material around a water collection pipe, wherein the temperature is 50 ° C. at a TOC concentration of 1 to 3 ppb. Of water permeated at a membrane permeation flux of 0.3 m ³ / m ² / day for 1 hour, and then washed at 25 ° C. with a TOC concentration of 1 to ³ ppb at a membrane permeation flow rate of 1.0 m ³ / m ^2. -When treated with d, TOC of raw water at the time when 3 hours have passed since the start of treatment
Fluid separation element relationship between the concentration (TOC _in) and permeate TOC concentration (TOC _out), characterized in that in the TOC _out -TOC _in ≦ 2ppb. 6. A case where water at 25 ° C. having a TOC concentration of 1 to 3 ppb is treated immediately after washing, and a case where water is stored for one month after washing, and thereafter, the water is stored at a temperature of 25 ° C. having a TOC concentration of 1 to 3 ppb. The fluid separation element according to claim 5, wherein, when water is treated, the difference in the permeate TOC concentration at the point of time when three hours have elapsed from the start of the treatment is within 5 ppb. 7. The fluid separation element according to claim 5, wherein the separation membrane is formed in an envelope shape with an adhesive containing trifunctional butadiene diol. 8. The adhesive comprises an isocyanate as a main component,
The fluid separation element according to claim 7, wherein the curing agent contains a trifunctional butadiene diol as a curing agent. 9. The fluid separation element according to claim 3, which is used for producing ultrapure water. 10. A fluid separation membrane module comprising the fluid separation element according to claim 3 housed in a pressure vessel.