JP2003145150A - Water treatment method and apparatus using membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment method wherein the energy used to adjust the temperature of a heating medium necessary to obtain a unit weight of permeated water can be saved and to provide a water treatment apparatus wherein the reduction in space is possible. SOLUTION: In a water treatment method comprising feeding the water to be treated under pressure to first-stage membrane modules 3a<1> and 3a<2> by a pump 2 to obtain permeated water from the permeated water outlets 6a<1> and 6a<2> of the modules 3a<1> and 3a<2> and to obtain intermediate concentrated water from the concentrated water outlets 5a<1> and 5a<2> of the modules 3a<1> and 3a<2> , and sequentially feeding the intermediate concentrated water obtained from the upstream membrane modules into the downstream membrane module 3b<1> , the intermediate concentrated water is fed into the membrane modules 3a<1> and 3a<2> situated downstream of the modules 3a<1> and 3a<2> after it is heated to a desired temperature by means of a heat exchanger 1a for heating.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water treatment method and a water treatment apparatus using a membrane module, and more specifically, a reverse osmosis membrane, a microfiltration membrane (MF membrane), and an ultrafiltration membrane (U).
The present invention relates to a water treatment method and a water treatment apparatus that use a membrane module having an F membrane) or a nanofiltration membrane (NF membrane) as a permeable membrane.

[0002]

2. Description of the Related Art Microfiltration membranes, ultrafiltration membranes, nanofiltration membranes,
Alternatively, a water treatment device using a one or more-stage membrane module having a permeable membrane such as a reverse osmosis membrane is intended to obtain permeated water that has permeated through a membrane using industrial water, tap water, recovered water, etc. as treated water. Has been used as. When the permeable membrane is a reverse osmosis membrane or a nanofiltration membrane, demineralized water is obtained as the permeated water, and when it is a microfiltration membrane or an ultrafiltration membrane, turbid water is obtained as the permeated water.

Since the total amount of permeated water obtained from such a water treatment device decreases as the viscosity of the treated water to be treated increases, when the water temperature of the treated water decreases as in winter, Before supplying the water to be treated having a lowered water temperature to the membrane module, a desired temperature, for example, a specific temperature within a range of 25 ° C to 40 ° C, is used by using a heating heat exchanger using steam as a heat medium. Water treatment has been carried out by raising the temperature to 1, and then supplying it to the membrane module. Furthermore, in water treatment using reverse osmosis membranes and nanofiltration membranes,
Silica or the like is deposited on the surface of the membrane when the saturation concentration at each water temperature is exceeded, and the flow path of the membrane is blocked, resulting in a decrease in the amount of permeated water. For that reason, the water to be treated in the water treatment device is heated by a heat exchanger for heating to increase the saturated dissolution concentration of silica etc. before supplying it to the permeable membrane before supplying it to the membrane module. The method of performing the used water treatment has been adopted.

As an example of such a conventional water treatment device,
Of the water treatment device 30a using the two-stage membrane module.
The rho diagram is shown in FIG. In FIG. 7, 1a indicates the water to be treated.
A heat exchanger for heating for heating, 2 is a pump for pressurization
Show. 3a¹, And 3a²Shows the first stage membrane module
And the permeable membrane 9a¹, 9a²Permeate side 8a
¹, 8a², And intermediate concentrated water side 7a¹, 7a²Divided into
In addition, the treated water inlet 4a¹4a²,During
Concentrated water outlet 5a¹5a², Permeate outlet 6a¹, 6a²To
Have. Also, 3b¹Shows the second stage membrane module,
Permeable membrane 9b¹Permeate side 8b¹, And concentrated water side 7
b¹, And the intermediate concentrated water inlet 4
b¹, Concentrated water outlet 5b¹, Permeate outlet 6b¹Have. Well
Further, 10 indicates a pressure reducing valve.

In the water treatment using the water treatment apparatus 30a of FIG. 7, the water to be treated is supplied to the heating heat exchanger 1a through the pipe 101 and is heated by being heat-exchanged with steam for heating. After that, the pressure is increased to a desired pressure by the pump 2 through the pipe 102, and the treated water supply pipe 103
It is supplied to the first stage membrane modules 3a ¹ and 3a ² .
A part of the water to be treated that has flowed into the membrane modules 3a ¹ and 3a ^{2 from the} water to be treated inlets 4a ¹ and 4a ^{2 is} absorbed by the permeable membrane 9a ¹ .
The membrane is treated with 9a ² to become permeate on the permeate sides 8a ¹ and 8a ² , and permeate is obtained from the permeate outlets 6a ¹ and 6a ² . The rest of the water to be treated is the intermediate concentrated water side 7a ¹ , 7a.
In a ^2, concentrated, intermediate retentate outlet 5a ^1, 5a ²
It flows out as more concentrated water. The intermediate concentrated water merges in the pipe 104c via the pipes 104a and 104b,
If necessary, the pressure is reduced by the pressure reducing valve 10 and the pressure is supplied to the second-stage membrane module 3b ¹ . Similar to the first-stage membrane module, a part of the supplied intermediate concentrated water is subjected to membrane treatment by the permeable membrane 9b ¹ to obtain permeated water from the permeated water outlet 6b ¹ and concentrated water from the concentrated water outlet 7b ^1. Is leaked. The permeated water obtained by the membrane modules 3a ¹ and 3a ² merges in the pipe 105c through the pipes 105a and 105b, merges with the permeated water obtained from the membrane module 3b ¹ flowing in the pipe 105d, and then in the pipe 105e. It flows in and is stored in, for example, a storage tank (not shown). Also, the membrane module 3b
^The concentrated water flowing out from ¹ is taken out by the pipe 106, and if necessary, subjected to wastewater treatment and the like and then discharged.

In the water treatment apparatus shown in FIG. 7, since the water to be treated is preheated by the heat exchanger 1a for heating, the water to be treated is treated even when the temperature of the water to be treated is low, such as in winter. The viscosity can be reduced and the amount of permeated water at a given pressure can be increased. However, since energy is required to adjust the temperature of the heating medium for heating such as steam used in the heating heat exchanger 1a, the energy consumption and the operating cost increase.

Therefore, in order to save the energy required for adjusting the temperature of the heating medium for heating, the heat of the concentrated water obtained from one or more membrane modules is used to heat the water to be treated. A water treatment device and a water treatment method capable of performing the above are known.

A flow chart of such a water treatment device 30b is shown in FIG. The water treatment device 30b of FIG. 8 is different from the water treatment device 30a of FIG. 7 mainly in that the membrane module 3b is used.
^The concentrated water flowing out from ¹ is supplied to the heat recovery heat exchanger 1b through the pipe 106, and the treated water and the concentrated water are heat-exchanged in the heat recovery heat exchanger 1b to heat the treated water. It is a point. By using such a water treatment device 30b to preheat the water to be treated, it is possible to save energy required for adjusting the temperature of the heating medium for heating.

[0009]

However, even in the water treatment method using the water treatment apparatus 30b, there is a problem that the energy saving required for the temperature adjustment of the heating medium for heating is insufficient. . Further, in the water treatment device 30b, it is necessary to newly install the heat recovery heat exchanger 1b, so that there is a problem that a new space and a new pipe are required.

Therefore, the object of the present invention is to obtain permeated water as compared with the case where the treated water is heated to a desired temperature in advance by a heat exchanger for heating and then supplied to the first-stage membrane module. , A water treatment method capable of saving energy used for adjusting the temperature of a heating medium for heating required to obtain the unit weight, a water treatment apparatus capable of implementing the water treatment method, and a space saving The purpose of the present invention is to provide a water treatment device that can be activated.

[0011]

Under the circumstances, as a result of intensive investigations by the present inventors, the present inventors completed the present invention by obtaining the following knowledge (1) to (4). (1) In a water treatment method using a membrane module having two or more stages, the intermediate concentrated water is heated to a desired temperature by a heat exchanger for heating, thereby using the conventional heat exchanger for heating. Saving energy for heating required to obtain a unit weight of permeated water obtained as compared with a method of supplying treated water heated to a desired temperature to a first-stage membrane module (2) In the water treatment method using one or more stages of membrane modules, the permeated water obtained is heat-exchanged with the water to be treated or the intermediate concentrated water to obtain a unit weight of the obtained permeated water. It is possible to further save the energy for heating required for (3)
In a water treatment device using one or more membrane modules,
At the inlet or outlet in the pressure vessel of the membrane module, a membrane module comprising a heat recovery heat exchanger for exchanging heat between treated water or intermediate concentrated water and concentrated water or permeated water, Space can be saved by using a water treatment device that is used as a membrane module in any stage. (4) In a water treatment device using one or more stages of membrane modules, heating for heating the water to be treated or the intermediate concentrated water to a desired temperature at the inlet or outlet of the pressure vessel of the membrane module. Space can be saved by using a water treatment device that uses a membrane heat exchanger installed as a membrane module at any stage.

That is, according to the present invention (1), the water to be treated is pressurized and supplied to the first-stage membrane module by a pump, and the permeated water is obtained from the permeated water outlet of the first-stage membrane module and the first-stage membrane module is obtained.
Two or more stages in which intermediate concentrated water is obtained from the intermediate concentrated water outlet of the stage membrane module, and the intermediate concentrated water obtained in the upstream membrane module is sequentially supplied to the downstream membrane module to obtain permeated water and concentrated water. In the water treatment method using the membrane module of
A membrane having two or more stages characterized in that the intermediate concentrated water is heated to a desired temperature by a heat exchanger for heating and then supplied to a membrane module located downstream of the heat exchanger for heating. A water treatment method using a module is provided. Further, the present invention (2) is characterized in that a pressure reducing valve is installed midway between the upstream membrane module and the heating exchanger, and the intermediate concentration is supplied to the downstream membrane module by the pressure reducing valve. By reducing the pressure applied to water, the amount of permeated water per membrane area of all the membrane modules used in the water treatment method is 0.8 to 1. It is intended to provide a water treatment method using the membrane module of two or more stages according to the invention (1), which is operated by adjusting so as to be doubled. Further, the present invention (3) is characterized in that the water to be treated or the intermediate concentrated water and the concentrated water or the permeated water are heat-exchanged in a heat recovery heat exchanger. A water treatment method using the membrane module having two or more stages described in 2) is provided. Further, the present invention (4) is characterized in that the heat recovery heat exchanger is installed at the outlet of the pressure vessel of the membrane module at any stage, and the intermediate concentrated water and the permeated water or the concentrated water are The present invention provides a water treatment method using a two or more-stage membrane module according to (3), characterized in that heat is exchanged in a heat recovery heat exchanger. Further, the present invention (5) is characterized in that the heating heat exchanger is installed at an outlet of a pressure vessel of a membrane module at any stage,
The water treatment method using two or more stages of membrane modules according to claim 1, wherein the intermediate concentrated water is heated to a desired temperature by the heating heat exchanger. Further, the present invention (6) is characterized in that, as the downstream membrane module, a membrane module having a smaller amount of permeated water per membrane area at the same pressure and the same temperature is used as compared with the upstream membrane module. ) Or (2) is provided. Further, the present invention (7) provides that the water to be treated is pressurized and supplied to the membrane module of the first stage by a pump to obtain the permeated water from the permeate outlet of the membrane module of the first stage, and the membrane of the first stage is also supplied. Obtain intermediate concentrated water or concentrated water from the outlet of intermediate concentrated water or concentrated water of the module 1
In a water treatment method using a membrane module having more than one stage, a heat recovery heat exchanger is installed at the inlet of the pressure vessel of the membrane module at any stage, and the treated water or the intermediate concentrated water and the permeated water or Disclosed is a water treatment method using one or more membrane modules, characterized in that concentrated water is heat-exchanged in the heat recovery heat exchanger. Further, the present invention (8) provides that the water to be treated is pressurized and supplied to the membrane module of the first stage by a pump to obtain the permeated water from the permeate outlet of the membrane module of the first stage, and the membrane of the first stage is also supplied. Obtain intermediate concentrated water or concentrated water from the outlet of intermediate concentrated water or concentrated water of the module 1
In a water treatment method using a stage or more membrane module, a heating heat exchanger is installed at the inlet of the pressure vessel of the membrane module of any stage, the treated water or the intermediate concentrated water, The present invention provides a water treatment method using one or more stages of membrane modules, which is characterized by heating to a desired temperature by the heating heat exchanger. In addition, the present invention (9)
Is supplied with pressure to the first-stage membrane module with a pump to obtain permeated water from the permeate outlet of the first-stage membrane module, and at the same time, the intermediate concentrated water or concentrated water of the first-stage membrane module is condensed. In a water treatment method using one or more membrane modules for obtaining intermediate concentrated water or concentrated water from a water outlet, the permeated water separated by the one or more membrane modules is treated with the treated water or the intermediate concentrated water and heat. It is intended to provide a water treatment method using one or more stages of membrane modules, which is characterized in that heat is exchanged in a recovery heat exchanger. In addition, the present invention (1
In 0), the heat recovery heat exchanger is installed at the inlet of the pressure vessel of the membrane module at any stage to treat the water to be treated or the intermediate concentrated water and the permeated water with the heat recovery heat exchanger. The present invention provides a water treatment method using one or more membrane modules according to (9), characterized in that heat is exchanged in an exchanger. In the present invention (11), the heat recovery heat exchanger is installed at the outlet of the pressure vessel of the membrane module at any stage, and the intermediate concentrated water and the permeated water are used for the heat recovery. (9) characterized in that heat is exchanged in a heat exchanger
The present invention provides a water treatment method using one or more stages of the membrane module described in 1. The present invention (12) also provides an inlet for water to be treated or intermediate concentrated water, one or more elements for obtaining permeate by subjecting the water to be treated or intermediate concentrated water to a membrane treatment, and a pressure vessel containing the element. And a membrane module having a permeate outlet and an intermediate concentrated water or an outlet for concentrated water in two or more stages, the intermediate concentrated water outlet of an upstream membrane module and the intermediate concentration of a downstream membrane module. It is intended to provide a water treatment device characterized in that a heating heat exchanger for heating the intermediate concentrated water is installed in the middle of a pipe connecting to a water inlet. Further, in the present invention (13), a heat recovery heat exchanger for heating the treated water using concentrated water obtained in the water treatment device as a heat medium is arranged in the middle of a pipe for supplying the treated water. The water treatment apparatus according to (12) above is provided. Further, the present invention (14) is further in the middle of a pipe connecting the intermediate concentrated water outlet of the upstream membrane module and the intermediate concentrated water inlet of the downstream membrane module, and on the upstream side of the heating heat exchanger. In the water treatment apparatus according to (12), a heat recovery heat exchanger that heats the intermediate concentrated water using the concentrated water obtained in the water treatment apparatus as a heat medium is provided. To do. Further, the present invention (15) provides an inlet for water to be treated or intermediate concentrated water, one or more elements for membrane-treating the water to be treated or intermediate concentrated water to obtain permeate, and a pressure vessel containing the element. And a membrane module having a permeated water outlet and an intermediate concentrated water or an outlet for concentrated water in one or more stages, wherein the water to be treated is provided in the middle of a pipe for supplying the water to be treated. It is intended to provide a water treatment device comprising a heat recovery heat exchanger for heating permeated water obtained by the treatment device as a heat medium. The present invention (16) also provides an inlet for the water to be treated or the intermediate concentrated water, one or more elements for subjecting the water to be treated or the intermediate concentrated water to a membrane treatment to obtain permeate, and a pressure vessel containing the element. A water treatment device using a membrane module having a permeate outlet and an intermediate concentrated water or an outlet for concentrated water in one or more stages, wherein the inlet part or the outlet part in the pressure vessel comprises:
It is intended to provide a water treatment device comprising a membrane module provided with a heat recovery heat exchanger for exchanging heat between treated water or intermediate concentrated water and concentrated water or permeated water. Further, the present invention (17) provides an inlet for water to be treated or intermediate concentrated water, one or more elements for obtaining permeate by subjecting the water to be treated or intermediate concentrated water to a membrane treatment, and a pressure vessel containing the element. And a permeated water outlet and a membrane module having an intermediate concentrated water or an outlet for the concentrated water in one or more stages, wherein the treated water or the intermediate water is added to the inlet or outlet of the pressure vessel. It is intended to provide a water treatment device comprising a membrane module provided with a heating heat exchanger for heating concentrated water to a desired temperature.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The water to be treated used in the present invention is not particularly limited because it varies depending on the type of membrane module used, the purpose of use of the treated water and the like.
Examples include industrial water, tap water, and recovered water. Further, turbid water obtained by turbidizing raw water by membrane treatment with a microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane) can also be used as the water to be treated in the present invention. Further, the water temperature of the water to be treated is not particularly limited, but the effect of the present invention is remarkably exhibited when the water temperature is lowered such as in winter.

A water treatment method according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a flowchart of the water treatment device 31a of this example. In FIG. 1, the first
The tiered membrane modules 3a ¹ and 3a ² are divided into permeate sides 8a ¹ and 8a ² and intermediate concentrated water sides 7a ¹ and 7a ² by permeable membranes 9a ¹ and 9a ² , respectively. , Treated water inlets 4a ¹ and 4a ² , intermediate concentrated water outlet 5
a ¹ and 5a ² and permeate outlets 6a ¹ and 6a ² . Also,
The second-stage membrane module 3b ¹ is divided into a permeated water side 8b ¹ and a concentrated water side 7b ¹ by a permeable membrane 9b ¹ , and further, an intermediate concentrated water inlet 4b ¹ , a concentrated water outlet 5b ¹ , and a permeated water. It has an outlet 6b ¹ . And the membrane module 3 of the first stage
In the middle of the pipe connecting the intermediate concentrated water outlets 5a ¹ and 5a ^{2 of} a ¹ and 3a ² and the intermediate concentrated water inlet 4b ^{1 of} the second stage membrane module 3b ¹ , the intermediate concentrated water is added with steam or the like. A heating heat exchanger 1a for heating is installed. Further, a pressure reducing valve 10 is installed downstream of the heating heat exchanger 1a in the middle of the piping. The pressure reducing valve 10 adjusts the flux by reducing the pressure applied to the intermediate concentrated water, and the initial flux becomes too large due to the excessive pressure applied to the intermediate concentrated water during operation. Prevents premature depletion. Further, the pressure reducing valve 10 is used for the second-stage membrane module 3
In b ¹ , the pressure of the intermediate concentrated water can be reduced so that SiO ₂ or the like does not exceed the saturation concentration and precipitates on the film surface. The pressure reducing valve 10 is an optional component in the present invention. Reference numeral 2 denotes a pressurizing pump.

For water treatment using the water treatment apparatus 31a of FIG.
The treated water is supplied to the pump 2 through the pipe 101.
Is supplied and pressurized to a desired pressure by the pump 2 to be processed.
Through the water supply pipe 103, the first-stage membrane module 3
a¹, And 3a²Is supplied to. Treated water inlet 4a¹Four
a²From membrane module 3a¹, And 3a²Inflow into
Part of the treated water is permeable membrane 9a¹, 9a²Membrane processed by
Permeate side 8a¹, 8a²Becomes permeated water at
Water outlet 6a¹, 6a²More permeate is obtained. To be processed
The rest of the water is the intermediate concentrated water side 7a¹, 7a²At the concentration
And the intermediate concentrated water outlet 5a¹5a²More intermediate concentrated water
Outflow. The intermediate concentrated water is supplied to the pipes 104a and 104b.
Through the pipe 104c and, if necessary, a pressure reducing valve
Reduced pressure by 10 and heat exchange for heating from pipe 104d
It is supplied to the vessel 1a and heated to the desired temperature with steam etc.
To be done. The desired temperature is the quality and quantity of the intermediate concentrated water.
It is set appropriately depending on which, etc., and indicates a specific temperature
Not a thing. The heated intermediate concentrated water is supplied to the pipe 104.
Second stage membrane module 3b from e¹Is supplied to. Supply
The resulting intermediate concentrated water is the same as in the first-stage membrane module,
Part of the permeable membrane 9b¹Permeate outlet 6b¹
More permeate is obtained, and the rest is concentrated water outlet 5b¹More concentrated
Runs out as water. Membrane module 3a¹, And 3a²By
The permeated water obtained is distributed through the pipes 105a and 105b.
A membrane module that joins the pipe 105c and flows through the pipe 105d.
3b¹It joins with the permeated water obtained from the pipe 105e.
Into the storage tank (not shown)
Saved. Also, the membrane module 3b ¹More outflow
The concentrated water is taken out through the pipe 106, and if necessary,
Wastewater is treated and discharged.

In the water treatment method of the first embodiment,
Usually, the amount of intermediate concentrated water is about 40 to 60% of the amount of water to be treated, so that a unit weight of the permeated water obtained is obtained as compared with the conventional method in which the entire amount of water to be treated is heated by the heat exchanger for heating. The energy used for the temperature adjustment of the heating medium for heating can be significantly saved. This energy saving amount is remarkable even if the energy required for increasing the driving power of the pump due to the decrease in the water temperature of the water to be treated is subtracted.

In the first embodiment, the pressure reducing valve 10 reduces the pressure applied to the intermediate concentrated water supplied to the second-stage module 3b ¹ to reduce the pressure per unit membrane area of the second-stage module 3b ^1. Permeate of the first stage membrane module 3a ¹ or 3a ² is 0.80 to 1.20 times, preferably 0.90 to 1.1.
When it is set to 0 times, it is possible to prevent the second-stage membrane module 3b ¹ from being damaged and disabled before the first-stage membrane modules 3a ¹ and 3a ² . Further, even when a membrane module having three or more stages is used, the amount of permeated water in the membrane module downstream of the heating heat exchanger can be adjusted by the pressure reducing valve installed upstream of the heating heat exchanger. .

The heat exchanger for heating is a heat for heating the water to be treated or the intermediate concentrated water by using a heat medium such as steam, that is, a heat medium other than concentrated water or permeated water obtained from the membrane module. An exchanger is shown and is distinguished from a heat recovery heat exchanger that heats the water to be treated or the intermediate concentrated water by using concentrated water or permeated water. Examples of such a heat exchanger for heating include a multi-tube heat exchanger and a plate heat exchanger, and an example of the heat medium includes steam.

The membrane module is, for example, a cross flow type in which the flow direction of the water to be treated or the intermediate concentrated water on the membrane surface of the permeable membrane is orthogonal to the flow direction of the permeated water with respect to the permeable membrane, or a dead end type. The following are listed. The membrane module is composed of a permeable membrane and a support structure, and known ones such as hollow fiber type, spiral type, flat plate type and tubular type can be used. Further, a heat-resistant membrane module can also be used. The permeable membrane is not particularly limited as long as it can obtain permeated water and concentrated intermediate concentrated water or concentrated water, and examples thereof include microfiltration membranes, ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes. Of these, it is preferable to use a reverse osmosis membrane. The reverse osmosis membrane is not particularly limited, and examples thereof include known reverse osmosis membranes such as a cellulose acetate-based asymmetric membrane and a synthetic polymer-based composite membrane. The support structure is a pressure vessel containing a permeable membrane inside,
It has the above-mentioned treated water or intermediate concentrated water inlet, intermediate concentrated water outlet or concentrated water outlet, and permeated water outlet, respectively.

The first-stage membrane module is a membrane module to which the water to be treated pressurized by a pump is supplied, and the second-stage membrane module is obtained from the first-stage membrane module. The membrane module to which the intermediate concentrated water is supplied to obtain the permeated water is shown. Hereinafter, similarly, the membrane module to which the intermediate concentrated water of the nth stage is supplied is referred to as the (n + 1) th stage membrane module. Further, the downstream membrane module means the n-th stage (n is n when the m-th stage membrane module is the upstream membrane module).
Membrane modules with a natural number> m). Also, FIG.
In the water treatment device 31a of
The pressure applied to the intermediate concentrated water obtained from the membrane module of the second stage can be lowered to adjust the amount of permeated water of the membrane module of the second stage. In this case, energy loss occurs due to pressure reduction. However, if the membrane module used in the second stage has a smaller amount of permeated water per membrane area at the same pressure and the same temperature than the membrane module used in the first stage, that is, if the solute rejection rate is high,
This pressure adjustment can be minimized, and the energy loss required for pressure adjustment can be minimized, which is preferable.
Further, by using the pressure reducing valve 10 in combination with a membrane module having a high rejection rate of the solute, or by using a membrane module having a high rejection rate of the solute without the pressure reduction valve 10, the downstream of the heating heat exchanger is The amount of permeated water per membrane area of the membrane module is 0.80 to 1.20 times, preferably 0.9 times the amount of permeated water per membrane area of any of the first stage membrane modules.
It can also be set to 0 to 1.10 times. When the reverse osmosis membrane module is used, for example, Nitto Denko ES-15 is used for the first stage membrane module and Nitto Denko ES is used for the second stage membrane module.
-20 may be used.

In the first embodiment, for convenience of description, the water treatment method and the water treatment apparatus using the two-stage membrane module have been described. However, the water treatment method using the three or more stages of membrane module is described. The first embodiment can also be applied to the water treatment device. In that case, the heat exchanger 1a for heating in FIG. 1 should be installed so as to heat the intermediate concentrated water of the membrane module of any stage such as the membrane module of the first stage and the membrane module of the second stage. You can Further, in the water treatment method and the water treatment apparatus using the membrane module of three or more stages, it is possible to use a plurality of heating heat exchangers 1a, but it is preferable to use only one heating heat exchanger 1a. It is preferable in that the treatment method and the water treatment device can be simplified.
In addition, in the water treatment device using the pressure reducing valve 10 or the pressure reducing valve 10 and the membrane module having a high rejection rate of the solute, the membrane downstream of the heating heat exchanger is used in a water treatment apparatus using two or more stages of membrane modules. When adjusting the amount of permeated water of the module, it is preferable to make the amount of permeated water per membrane area of all the membrane modules of an arbitrary stage the same. In the present invention, the term "intermediate concentrated water" refers to any one of the first to (p-1) th stages when the lowest stage is the pth stage in a water treatment method using two or more stages of membrane modules. It shows the water that is concentrated on the side of the intermediate concentrated water of the membrane module of the qth stage and is obtained from the outlet of the intermediate concentrated water and is supplied to the membrane module of the (q + 1) th stage. Further, the concentrated water refers to the water discharged from the concentrated water outlet in the lowermost membrane module.

A water treatment method according to the second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a flow chart of the water treatment device 31b of this example. 2, the same components as those in FIG. 1 are designated by the same reference numerals, the description thereof will be omitted, and different points will be mainly described. The water treatment device 31b of FIG. 2 is different from the water treatment device 31a of FIG. 1 in that a heat recovery heat exchanger 1b is installed in a pipe 101 for supplying water to be treated, and a pipe 106 through which concentrated water flows out.
Is a pipe for the heat medium of the heat recovery heat exchanger 1b. That is, the concentrated water flowing out from the membrane module 3b ¹ is supplied to the heat recovery heat exchanger 1b through the pipe 106,
The point of exchanging heat with the water to be treated in the heat recovery heat exchanger 1b to heat the water to be treated, then pressurizing with the pump 2, and supplying the water to the first-stage membrane modules 3a ¹ and 3a ^2. Is. Such a water treatment device 31b heats the water to be treated by preliminarily exchanging heat with concentrated water having a predetermined temperature, and thus saves energy required for adjusting the temperature of the heat medium of the heat exchanger 1a for heating. can do. Further, since the temperature of the water to be treated at the pump inlet is higher than that of the water treatment method of the first embodiment, when the desired temperature is the same, the pump required for obtaining the maximum amount of permeated water can be obtained. The discharge pressure can be reduced. The second embodiment can also be applied to a water treatment method and a water treatment device using a membrane module having three or more stages.

The heat recovery heat exchanger 1b is not particularly limited as long as it has a wall for separating the water to be treated or the intermediate concentrated water to be heated from the concentrated water or the permeated water for supplying heat. , For example, surface heat exchangers and liquid-coupled indirect heat exchangers. As the surface heat exchanger, a multi-tube cylindrical heat exchanger, a double tube heat exchanger, a plate heat exchanger,
And a spiral heat exchanger. Among these, the plate heat exchanger is preferable because it has high heat exchange efficiency and is easy to handle.

A water treatment method according to the third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a flowchart of the water treatment device 31c of this example. In FIG. 3, the same components as those of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Differences from FIG. 1 will be mainly described. The main difference between the water treatment device 31c of FIG. 3 and the water treatment device 31a of FIG. 1 is that the heat recovery heat exchanger 1b is provided upstream of the heating heat exchanger 1a in the middle of the pipe through which the intermediate concentrated water flows out. Is installed, and the pipe 106 through which the concentrated water flows out is used as a heat medium pipe of the heat recovery heat exchanger 1b. That is,
The heat recovery heat exchanger 1b allows the first-stage membrane module 3
a ¹ and 3a ² , the intermediate concentrated water and the concentrated water flowing through the pipe 106 are heat-exchanged, and then heated to a desired temperature by the heat exchanger 1a for heating, It is supplied to the stage membrane module 3b ¹ . Such a water treatment device 31c
Since the intermediate concentrated water is heated by previously exchanging heat with the concentrated water having a predetermined temperature, it is possible to further save energy required for adjusting the heat medium of the heating heat exchanger 1a. Further, the third embodiment can be applied to a water treatment method and a water treatment apparatus using a membrane module having three or more stages.

A water treatment method according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a flow chart of the water treatment device 31d of this example. 4, the same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Differences from FIG. 1 will be mainly described. The water treatment device 31d of FIG. 4 is different from the water treatment device 31a of FIG. 1 in that a heat recovery heat exchanger 1b is installed in a pipe 101a for supplying water to be treated, and a pipe 105e through which permeated water flows out. Is a pipe for the heat medium of the heat recovery heat exchanger 1b. That is, the permeated water obtained from the membrane modules 3a ¹ , 3a ² and 3b ¹ is 105a,
It flows through 105b and 105c, merges with the pipe 105e, and flows into the heat recovery heat exchanger 1b. In the steady state of operation of the apparatus, the water to be treated is heat-exchanged with the permeated water having a predetermined temperature in the heat recovery heat exchanger 1b, and then,
It is heated to a desired temperature by the heating heat exchanger 1a,
After being pressurized by the pump 2, the first stage membrane module 3
a ¹ and 3 a ² . Such a water treatment device 3
1d heats the water to be treated by exchanging heat with the permeated water having a predetermined temperature in advance, so that the energy required for adjusting the heat medium of the heat exchanger 1a for heating can be saved. Further, the fourth embodiment can be applied to a water treatment method and a water treatment device using a membrane module having three or more stages. It is also possible to use two heat recovery heat exchangers 1b, one of which performs heat exchange between concentrated water and treated water, and the other of which performs heat exchange between permeated water and treated water.

Further, in the water treatment device 31d shown in FIG. 4, the installation locations of the heat recovery heat exchanger 1b and the heating heat exchanger 1a are changed so that both the heat exchangers are supplied with intermediate concentrated water.
The water treatment device may be installed in the middle of the pipe 104d to be supplied to the membrane module 3b ^{1 of the} stage, and the pipe 105e may be used as the heat medium pipe of the heat recovery heat exchanger 1b. In the water treatment method using the water treatment device, the intermediate concentrated water is pressure-adjusted by the pressure reducing valve 10, and then is subjected to heat exchange with permeated water having a predetermined temperature in the heat recovery heat exchanger 1b, and then, It is heated to a desired temperature by the heating heat exchanger 1a and supplied to the second stage membrane module 3b ¹ .

In addition to the above-described embodiment, for example, in a water treatment device using a single-stage membrane module and arranging a heat recovery heat exchanger 1b and a heating heat exchanger 1a in the preceding stage of the membrane module, The recovery heat exchanger 1b can also take a form of exchanging heat between the water to be treated and the permeated water. It is also possible to use two heat recovery heat exchangers 1b, one of which performs heat exchange between concentrated water and treated water, and the other of which performs heat exchange between permeated water and treated water.

Next, an example of the membrane module used in the water treatment apparatus of the present invention will be described with reference to FIG. FIG. 5 is a schematic view of the membrane module of this example. Membrane module 40
a is an inlet 11 of the water to be treated or the intermediate concentrated water, membrane elements 14a and 14b having a permeable membrane such as a reverse osmosis membrane that obtains permeated water by subjecting the water to be treated or the intermediate concentrated water to a membrane, and the membrane element 14a, Cylindrical pressure vessel 1 containing 14b
3, a permeated water outlet 20, and an intermediate concentrated water outlet 21. The membrane module has an outlet portion in the pressure vessel 13,
A heat exchanger 16 for exchanging heat between the water to be treated or the intermediate concentrated water to be treated in the membrane module and a heat medium such as steam, concentrated water or permeated water is installed. 12 is a tube cap, 15a and 15b are joints,
17 indicates an end plate. The heat exchanger 16 is, for example, a plate-type heat exchanger, and includes a heating medium inlet 18 for heating, such as steam, concentrated water or permeated water, which communicates from the end plate 17 to the outside of the system, and steam, concentrated water or permeated water. Heating medium outlet 19 for heating, an intermediate concentrated water inlet 22,
It has an intermediate concentrated water outlet 21. Membrane module 40
The heat exchanger 16 incorporated in a may be the heat recovery heat exchanger 1b described above, or may be the heating heat exchanger 1a. In addition, the heat exchanger 16 includes the end plate 17
It can also be integrated with. The outlet of the membrane module means the membrane elements 14a and 14b and the intermediate concentrated water outlet 21.
Say the area between and. In the membrane module 40a, the water to be treated or the intermediate concentrated water passes through the pipe 111 and the inlet 11
Further, it flows into the pressure vessel 13, and the water to be treated or the intermediate concentrated water sequentially flows into the membrane elements 14a and 14b, for example, as shown by the arrow 112, and a part of the water is treated by a permeable membrane not shown in FIG. Membrane treatment is performed to form permeated water as shown by dotted lines 114a and 114b.
As shown in 14 c, it reaches the permeate outlet 20 through the outside of the heat exchanger 16 and is taken out from the pipe 115. The remainder is the membrane element 14a, as shown by the solid line 113.
In 14b, it is concentrated into intermediate concentrated water, which flows into the heat exchanger 16 through the intermediate concentrated water inlet 22 and
It is heated by a heating heat medium such as steam, permeated water, or concentrated water that is a heat medium flowing inside, and then flows out from the intermediate concentrated water outlet 21 to the pipe 118. Heat exchanger 16
A heat medium such as water vapor, permeated water, or concentrated water flowing through the inside flows out to the pipe 117. As aspect use of a membrane module 40a, for example, in FIG. 1, in place of the membrane modules 3a ¹ and 3a ² of the first stage, using a membrane module 40a in 2 groups in which the heat exchanger 16 and the heating heat exchanger The heating heat exchanger 1a does not need to be installed outside the membrane module. In addition, the heat exchanger 16
As a mode of use of the membrane module 40a having a heat recovery heat exchanger for heat recovery, for example, in FIG. 3, instead of the first stage membrane modules 3a ¹ and 3a ² , concentrated water in the pipe 106 is used as heat of the heat exchanger 16. By using two membrane modules 40a as a medium, it is not necessary to install the heat recovery heat exchanger 1b outside the membrane module. In addition, in FIG. 1 and FIG. 3, one of the first stage membrane modules 3a ¹ and 3a ²
Using the membrane module 40a instead of the base, and
It is also possible to use one membrane module 40a in place of the membrane modules 3a ¹ and 3a ² of the first stage in the above-mentioned present inventions (4), (5), (11), (16) and (17). It is included. As the membrane module 40a, one or more units can be used as an arbitrary nth-stage membrane module other than the lowest-stage membrane module that discharges concentrated water, for example, a third-stage membrane module. When there are a plurality of n-th stage membrane modules, all of the plurality of membrane modules can be replaced with the membrane module 40a. By using a water treatment device using two or more stages of membrane modules having such a membrane module 40a, piping and space for installing the heat recovery heat exchanger outside the membrane module can be omitted, and By using the water treatment device, a simple water treatment method can be obtained.

Next, another example of the membrane module used in the water treatment apparatus of the present invention will be described with reference to FIG. Figure 6
[Fig. 3] is a schematic view of a membrane module 40b of this example. 6, the same components as those in FIG. 5 are designated by the same reference numerals, the description thereof will be omitted, and different points will be mainly described. That is, the membrane module 40b of FIG. 6 is different from the membrane module 40a of FIG. 5 in that the heat exchanger 16 is provided at the upstream portion of the membrane elements 14a and 14b, that is, at the inlet portion. The water to be treated or the intermediate concentrated water flowing through the pipe 111 flows into the heat exchanger 16 through the inlet 11 and is heated by exchanging heat with steam, permeated water or concentrated water, which is a heating medium for heating. , Outflow from the outlet 23 from the heat exchanger 16, and as with the membrane module 40a of FIG. 5, permeated water subjected to membrane treatment in the membrane elements 14a and 14b and concentrated intermediate concentrated water or concentrated water are obtained. The inlet part of the membrane module refers to a region between the membrane elements 14a and 14b and the inlet 11 of the water to be treated or the intermediate concentrated water. As a usage mode of the membrane module 40b, for example, in the water treatment device 31a shown in FIG.
Instead of b ^1, by using the heat exchanger 16 is a membrane module 40b is a temperature heat exchanger pressure eliminates the need to install a heat exchanger 1a for heating the membrane module outside.
Further, for example, in the water treatment device 31b shown in FIG.
By using two membrane modules 40b, which are heat recovery heat exchangers in which the heat exchanger 16 uses concentrated water in the pipe 106 as a heat medium, instead of the first-stage membrane modules 3a ¹ and 3a ² , It is not necessary to install the heat recovery heat exchanger 1b outside. Further, the membrane module 40b, in a water treatment device using a single-stage membrane module, heat-exchanges the water to be treated with a heating heat medium such as steam, permeate or concentrated water in a heat recovery heat exchanger. A water treatment device and a water treatment method can also be used. In the water treatment device using one or more membrane modules, one or more membrane modules 40b can be used as an arbitrary nth, for example, third membrane module. Further, any of the n-th stage membrane modules can be used as the membrane module 40b.

[0030]

The present invention will be described in more detail with reference to the following examples, which are merely examples and do not limit the present invention.

Comparative Example 1 Using the water treatment apparatus 30a having the flow shown in FIG. 7, water treatment was performed under the following apparatus specifications and water treatment conditions. The water treatment method was the same as the method described in paragraph 0005 of the present specification. As the water to be treated, the raw water was industrial water, and the raw water was subjected to pretreatment such as turbidity, pH adjustment, deaeration and the like.

Water to be treated; silica concentration 20 mg / l, water temperature in front of heat exchanger for heating 12 ° C., heat exchanger for heating; plate type heat exchanger, steam as heat medium, heat exchanger for heating Temperature of treated water heated by (T
1); 25 ° C. ・ Upper limit of concentration ratio (saturated solubility of silica / silica concentration in treated water); saturated solubility of silica at 6.425 ° C. 128 mg / l, silica concentration in treated water 20 mg
Value divided by / l / Membrane module; 8 inch element, 3 modules in 1 module reverse osmosis membrane module ES-15 (Nitto Denko Corporation)

In this example, the flow rate of the water to be treated (F0) is 1
1.9 t / hr is set, and 10 t / hr is obtained as the permeated water amount which is the silica precipitation limit at T1 = 25 ° C. The pump pressure was set to 0.59 MPa in consideration of the pressure loss in the membrane module in order to obtain this amount of permeated water. Also, considering the contamination of the membrane surface of the permeable membrane, 1 to 1.
The operation was performed so that permeated water of about 5 t / hr could be obtained. Specifically, the flow rate to the first stage membrane modules 3a ¹ and 3a ² is set to 11.9 t / hr, and the first stage membrane module 3
The total flow rate of the intermediate concentrated water from a ¹ and 3a ² is 5.3.
t / hr, the first stage membrane modules 3a ¹ and 3a ²
The total amount of permeated water from was 6.6 t / hr. The silica concentration of the permeated water was 1 mg / l or less, and the silica concentration of the intermediate concentrated water was 45 mg / l. The flow rate of the concentrated water from the second stage membrane module 3b ¹ was 1.9 t / hr,
The amount of permeated water from the three-stage membrane module 3b ¹ is 3.4 t / h.
It was r. The silica concentration of the concentrated water was 128 mg / l.

<Energy calculation> Treated water 11.9t /
Energy is required to heat hr from 12 ° C to 25 ° C. Therefore, as for the heating energy, the energy for heating 1 kg of water at 1 ° C. is 4184 J / (kg · ° C.), so (25 ° C.-12 ° C.) × 11.9 × 10 ³ kg / hr.
× 4184 J / (kg · ° C) = 6.47 × 10 ⁵ kJ /
hr, meanwhile, pump power is 3.3 kW = 1.19 × 10
^The total was ⁴ kJ / hr, which was 6.59 × 10 ⁵ kJ / hr. The amount of permeated water obtained was 10 t / hr (permeated water temperature 25 ° C.).

Comparative Example 2 Water treatment was carried out using the water treatment apparatus 30b having the flow shown in FIG. 8, and in order to effectively utilize heat energy, the water to be treated at a temperature of 12 ° C. was treated with the second-stage membrane module 3b ¹ The concentrated water having a flow rate of 1.9 t / hr and the heat recovery heat exchanger 1b are heat-exchanged with each other, and then heated by the heat exchanger 1a for heating to 2
After heating up to 5 ° C., all were supplied to the first stage membrane modules 3a ¹ and 3a ² except for the water treatment device of Comparative Example 1,
The same operation as the water treatment method and water treatment conditions was performed. The temperature and flow rate at each location are shown below.

Inlet temperature before the heat recovery heat exchanger 1b for treated water: 12 ° C. Temperature after leaving the heat recovery heat exchanger 1b for treated water; 14
℃ Inlet temperature before heat recovery heat exchanger 1b for concentrated water; 25 ° C Outlet temperature after exiting heat recovery heat exchanger 1b for concentrated water; 1
4 ° C Flow rate of treated water (F0); 11.9t / hr

<Energy Calculation> Heating energy is (25 ° C.-14 ° C.) × 11.9 × 10 ³ kg / hr × 4
184J / (kg ・ ° C) = 5.48 × 10 ⁵ kJ / h
r, meanwhile, the pump power is 3.3 kW = 1.19 × 10 ⁴
The total kJ / hr was 5.60 × 10 ⁵ kJ / hr. The amount of permeated water is 10 t / hr (permeated water temperature 25
℃).

Example 1 Using the water treatment apparatus 31a shown in FIG. 1, the discharge pressure (operating pressure) of the pump was set to 0.59 MPa × 1.53 = 0.90 MPa, and the treated water at 12 ° C. was treated in the first stage. The total amount of permeated water obtained by treating with the membrane module is 6.6 t / hr.
The pressure reducing valve 10 in FIG.
After depressurizing the intermediate concentrated water to 9 MPa and then heating the intermediate concentrated water to 25 ° C. by the heating heat exchanger 1a, the water treatment device, the water treatment method, and the water treatment conditions of Comparative Example 1 were the same. Driven the way. The reason for increasing the pump operating pressure is 12
The permeated water amount in the case of 25 ° C. is 65.
Since it is 5%, the operating pressure is 1 / 0.655 = 1.53.
It depends on doubling.

The saturated solubility of silica to be treated water supplied to the first stage membrane module at a water temperature of 12 ° C. is 128 mg / l.
And the silica concentration of the intermediate concentrated water obtained in the first stage membrane module (silica concentration 45 mg / l) is less than the saturation concentration. Since the intermediate concentrated water was heated before being sent to the second stage membrane module 3b ¹ , it means that the intermediate concentrated water of 5.3 t / hr was heated from 12 ° C to 25 ° C. Further, the permeated water of the second-stage membrane module 3b ¹ is 3.4 t /
Although it is 25 ° C. in hr, the total permeated water of the first-stage membrane modules 3a ¹ and 3a ² is 12 ° C. at 6.6 t / hr, so the total permeated water temperature is 16 ° C. at 10 t / hr.
Is.

<Energy calculation> The heating energy is (25 ° C-12 ° C) x 5.3 t / hr x 4184 J /
(Kg · ° C.) = 2.88 × 10 ⁵ kJ / hr, while the pump power was 5.1 kW = 1.84 × 10 ⁴ kJ / hr, which was 3.06 × 10 ⁵ kJ / hr in total. The amount of permeated water was 10 t / hr (permeated water temperature 16 ° C.).

According to the first embodiment, the power is increased to increase the operating pressure of the pump, but the energy required for heating is drastically reduced. A significant energy saving of 50% or more per amount of permeated water.

Example 2 Example 1 was repeated except that the intermediate concentrated water to be fed to the second-stage membrane module was heated by the heat exchanger 1a for heating to 40 ° C. which is the normal upper limit temperature of use of the membrane module. The operation was performed using the water treatment device 31a in the same manner as in. In this case, 40 ℃
Since the silica saturation concentration at 160 mg / l, the permeated water amount of the second stage membrane module 3b ¹ was set to 3.8 t / hr. Concentrated water of the second stage membrane module 3b ¹ is 1.5 t /
The silica concentration was 160 mg / l in hr.

<Energy calculation> The energy for heating is (40 ° C-12 ° C) x 5.3 t / hr x 4184 J /
(Kg · ° C.) = 6.21 × 10 ⁵ kJ / hr, while pump power is 5.1 kW = 1.84 × 10 ⁴ kJ / hr,
The total was 6.39 × 10 ⁵ kJ / hr. Also,
The amount of permeated water was 10.4 t / hr (permeated water temperature 23 ° C.).

In Example 2, the amount of concentrated water was reduced and the total amount of permeated water obtained was improved. Further, as compared with Comparative Example 1, the amount of permeated water increased by 4%, although the energy consumption decreased by 3%, so the energy consumption per unit amount of permeated water decreased by about 7%.

Example 3 Water treatment was performed using the water treatment apparatus 31b of FIG. 2, and concentrated water (25 ° C., 1.9 t / h) of the second stage membrane module 3b ¹ was treated.
r) is passed through the pipe 106 to the heat recovery heat exchanger 1b to exchange heat with the water to be treated at 12 ° C. supplied to the first-stage membrane modules 3a ¹ and 3a ² , and the ^second- stage membrane module 3a ¹ . The operation is performed in the same manner as in Example 1 except that the intermediate concentrated water supplied to 3b ¹ is heated to 25 ° C. in the heating heat exchanger 1a and the operating pressure of the pump is set to 0.85 MPa. It was A plate heat exchanger was used as the heat recovery heat exchanger 1b.

In the heat recovery heat exchanger 1b, the inlet temperature of the treated water is 12 ° C., the inlet temperature of the concentrated water is 25 ° C., the outlet temperature of the concentrated water is 14 ° C., the outlet temperature of the treated water is Was 14 ° C. Since the water to be treated is 14 ° C,
The operating pressure of the pump was 1.44 times that of Comparative Example 1, that is, 0.59 × 1.44 = 0.85 MPa, and the permeated water obtained in the first-stage membrane modules 3a ¹ and 3a ² was operated. The total amount was kept at 6.6 t / hr.

<Energy calculation> Heating energy is (25 ° C-14 ° C) x 5.3 t / hr x 4184 J /
(Kg · ° C.) = 2.44 × 10 ⁵ kJ / hr, while the pump power was 4.8 kW = 1.73 × 10 ⁴ kJ / hr, totaling 2.61 × 10 ⁵ kJ / hr. The amount of permeated water was 10 t / hr (permeated water temperature 18 ° C.).

According to Example 3, as compared with Example 1 in which heat was not recovered from the concentrated water, per unit weight of permeated water,
Energy savings of 15% were achieved. Further, compared with Comparative Example 2, energy saving of 53% can be achieved,
The method according to this example has an energy advantage.

Example 4 Water treatment was carried out using the water treatment apparatus 31c of FIG. 3, and the concentrated water of the second-stage membrane module 3b ¹ , that is, the total concentrated water was circulated to the heat recovery heat exchanger 1b through the pipe 106. , Heat-exchange with the intermediate concentrated water of 12 ° C. supplied to the second-stage membrane module 3b ¹ and heat the intermediate concentrated water to 25 ° C. in the heat exchanger 1a for heating. The operation was performed in the same manner as in Example 1 except for the above.

In the heat recovery heat exchanger 1b, the inlet temperature of the intermediate concentrated water is 12 ° C., the inlet temperature of the concentrated water is 25 ° C., the outlet temperature of the concentrated water is 14 ° C., the outlet temperature of the intermediate concentrated water. Was 16 ° C. The operating pressure of the pressurizing pump is 1.53 times, that is, 0.59 × 1.53 = 0.90M
Operated at Pa, the first-stage membrane modules 3a ¹ and 3a ²
The total amount of permeated water obtained in 1. was maintained at 6.6 t / hr.

<Energy calculation> The energy for heating is (25 ° C-16 ° C) x 5.3 t / hr x 4184 J /
(Kg · ° C.) = 2.00 × 10 ⁵ kJ / hr, while the pump power was 5.1 kW = 1.84 × 10 ⁴ kJ / hr, which was 2.18 × 10 ⁵ kJ / hr in total. The amount of permeated water was 10 t / hr (permeated water temperature 16 ° C.).

According to the fourth embodiment, energy saving of 29% can be achieved as compared with the first embodiment in which the heat is not recovered. Further, as compared with Example 3 in which heat was exchanged with the water to be treated of the first-stage membrane module, energy saving was further achieved by 16%.

Example 5 Water treatment is performed using the water treatment device 31d shown in FIG.
Membrane module 3a¹, And 3a²Permeate, obtained from
And the second stage membrane module 3b¹The permeated water of the pipe 105
It is circulated to the heat recovery heat exchanger 1b by e, and the first-stage membrane is
Module 3a ¹, And 3a²12 ° C to be supplied to
Heat exchange with water, first stage membrane module 3a¹, And 3
a²Water to be supplied to the heat exchanger 1a for heating
Except that it is heated up to 25 ° C.
The operation was carried out in the same manner as the setting, water treatment method and water treatment conditions.
The temperature and flow rate at each location are shown below. Also,
A plate heat exchanger is used as the heat recovery heat exchanger 1b.
Using.

[0054] Inlet temperature of heat exchanger for heat recovery of treated water; 12 ℃ Outlet temperature of heat exchanger for heat recovery of treated water: 21 ° C Inlet temperature of heat exchanger for heat recovery of all permeated water; 25 ° C Outlet temperature of heat exchanger for heat recovery of all permeate; 14 ℃

<Energy calculation> The heating energy is (25 ° C-21 ° C) x 11.9 t / hr x 4184 J /
(Kg · ° C.) = 1.99 × 10 ⁵ kJ / hr, while the pump power was 3.3 kw = 1.19 × 10 ⁴ kJ / hr, which was 2.11 × 10 ⁵ kJ / hr in total. The amount of permeated water was 10 t / hr (permeated water temperature 18 ° C.).

In Example 5, energy saving of 62% was achieved as compared with Comparative Example 2 in which heat was recovered from concentrated water.

From the energy calculations of the above Comparative Examples and Examples, the following was found. Example 1 in which the operating pressure was increased within a range in which the silica concentration of the intermediate concentrated water obtained from the first-stage membrane module did not exceed the saturation concentration to obtain the same amount of permeated water as in Comparative Example 1, and heating. Example 2 in which the same experiment as in Example 1 was carried out except that the temperature of the intermediate concentrated water was raised to 40 ° C. with the use heat exchanger, the permeated water could be obtained more energy-saving than the comparative example 1. Further, the concentrated water and the water to be treated were heat-exchanged, and the operating pressure was raised within a range not exceeding the saturated concentration to obtain the same amount of permeated water as in Comparative Example 1.
Was able to obtain permeated water with energy saving as compared with Comparative Examples 1 and 2. In Example 4 in which the intermediate concentrated water and concentrated water of the second-stage membrane module were heat-exchanged, Comparative Example 1
And energy saving was achieved as compared with Comparative Example 2. Second
In Example 5 in which the intermediate permeated water of the staged membrane module and the water to be treated are heat-exchanged, compared to Comparative Example 1 and Comparative Example 2,
Energy saving was achieved.

Reference Example 1 For the above-described comparative example and example, consider the cost calculation for operating the apparatus. The steam used for heating is 3 yen per kg, and the electric power used for the pump is 15 per kWh.
Let it be a circle. The amount of heat obtained from 1 kg of steam is 2.4.
If it is 3 × 10 ³ kJ, the water vapor is 1.23 × 10 ^-3.
Yen / kJ (hereinafter referred to as constant a), electric power is 4.17
It is × 10 ^-3 yen / kJ (hereinafter, this is referred to as a constant b), and the cost per hour is calculated as shown in Table 1.

[0059]

[Table 1] ───────────────────────────────── Comparative Example 1 6.47 × 10 ⁵ a + 1.19 × 10 ⁴ b = 845 yen Comparative Example 2 5.48 × 10 ⁵ a + 1.19 × 10 ⁴ b = 724 yen Example 1 2.88 × 10 ⁵ a + 1.84 × 10 ⁴ b = 431 yen Example 2 6.21 × 10 ⁵ a + 1.84 × 10 ⁴ b = 841 yen Example 3 2.44 × 10 ⁵ a + 1.73 × 10 ⁴ b = 372 yen Example 4 2.00 × 10 ⁵ a + 1.84 × 10 ⁴ b = 323 yen Yen Example 5 1.99 × 10 ⁵ a + 1.19 × 10 ⁴ b = 294 Yen ─────────────────────────────── ───

In the reference example 1, the cost is calculated by adding the amount obtained by multiplying the energy amount of each of the electric energy and the heat amount required to obtain the permeated water by a constant, and calculating the cost together with the energy calculation. It can be used as an indicator. Further, it can be seen that Examples 1, 3, 4, and 5 of the present invention are superior not only in the energy aspect to the comparative example but also in the cost aspect to the comparative examples 1 and 2.

Regarding CO ₂ emission amount, CO ₂ per unit weight of water vapor and per unit energy of electric power
₂ It can be calculated simply by converting using the emission amount,
This can also be used as a management index.

[0062]

According to the water treatment method of the present invention, the energy required for adjusting the temperature of the heating medium for heating, which is required to obtain the unit weight of the permeated water obtained, can be saved. Further, the water treatment device of the present invention can reliably carry out the water treatment method. Further, by using the water treatment device of the present invention as a water treatment device including a membrane module containing a heat recovery heat exchanger, it is possible to provide a space-saving water treatment device.

[Brief description of drawings]

FIG. 1 is a flow diagram showing a water treatment device according to a first embodiment of the present invention.

FIG. 2 is a flow diagram showing a water treatment device according to a second embodiment of the present invention.

FIG. 3 is a flow diagram showing a water treatment device according to a third embodiment of the present invention.

FIG. 4 is a flow diagram showing a water treatment device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic view showing a membrane module containing a heat exchanger used in the water treatment device of the present invention.

FIG. 6 is a schematic view showing another embodiment of a membrane module having a heat exchanger used in the water treatment device of the present invention.

FIG. 7 is a flowchart showing a conventional water treatment device.

FIG. 8 is a flowchart showing another conventional water treatment device.

[Explanation of symbols]

1a Heating heat exchanger 1b Heat recovery heat exchanger 2 Pumps 3a ¹ , 3a ² , 3b ¹ Membrane modules 4a ¹ , 4a ² Treated water inlet 4b ¹ Intermediate concentrated water inlet 5a ¹ , 5a ² Intermediate concentrated water outlet 5b ¹ concentrated water outlet 6a ¹ , 6a ² , 6b ¹ permeated water outlet 7a ¹ , 7a ² intermediate concentrated water side 7b ¹ concentrated water side 8a ¹ , 8a ² , 8b ¹ permeated water side 9a ¹ , 9a ² , 9b ¹ permeate Membrane 10 Pressure reducing valve 11 Inlet for treated water or intermediate concentrated water 12 Tube cap 13 Pressure vessels 14a, 14b Membrane elements 15a, 15b Joint 16 Heat exchanger 17 End plate 18 Permeate or concentrated water for heat recovery heat exchanger Inlet 19 Outlet of permeate or concentrated water to heat recovery heat exchanger 20 Permeate outlet 21 Intermediate concentrated water outlet 22 Intermediate concentrated water inlet to heat exchanger 23 Treated water or intermediate concentrated water from heat exchanger Water outlet 30 a, 30b Conventional water treatment devices 31a to 31d Water treatment devices 40a, 40b according to the water treatment method of the present invention Membrane modules 101, 102, 103, 104a, 104b, 104 incorporating heat exchangers.
c, 104d, 105a to e, 106, 111, 11
5,116,117,118 Piping

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F28F 27/00 511 F28F 27/00 511F F term (reference) 4D006 GA03 GA06 GA07 HA01 HA21 HA41 HA61 JA53A JA57A JA65A JA66A KA01 KA14 KA15 KA16 KA52 KA54 KA56 KA63 KA64 KA67 KB30 KE05Q KE05R KE07P KE16P KE16Q MA01 MA02 MA03 MB02 MB15 PA01 PB02 PB06 PB22 PB25 PB26 PC51 PC54

Claims (17)

[Claims] 1. Water to be treated is supplied under pressure to a membrane module of the first stage by a pump to obtain permeated water from a permeate outlet of the membrane module of the first stage and an intermediate concentrated water of the membrane module of the first stage. In a water treatment method using two or more stages of membrane modules, the intermediate concentrated water is obtained from the outlet, and the intermediate concentrated water obtained in the upstream membrane module is sequentially supplied to the downstream membrane module to obtain permeated water and concentrated water. The intermediate concentrated water is heated to a desired temperature by a heat exchanger for heating and then supplied to a membrane module located downstream of the heat exchanger for heating. Water treatment method using a membrane module. 2. A pressure reducing valve is installed in the middle of piping between the upstream membrane module and the heating exchanger, and pressure applied to the intermediate concentrated water supplied to the downstream membrane module by the pressure reducing valve. By reducing the amount of permeated water per membrane area of all the membrane modules used in the water treatment method is 0.8 to 1.2 times the permeated water amount per membrane area of the first-stage membrane module. The water treatment method using a membrane module of two or more stages according to claim 1, wherein the water treatment method is performed by adjusting the above. 3. A heat recovery heat exchanger for exchanging heat between the water to be treated or the intermediate concentrated water and the concentrated water or the permeated water according to claim 1 or 2.
A water treatment method using a membrane module having more than two stages. 4. The heat recovery heat exchanger is installed at the outlet of the pressure vessel of the membrane module at any stage, and the intermediate concentrated water and the permeated water or the concentrated water are transferred to the heat recovery heat exchanger. The water treatment method using two or more stages of membrane modules according to claim 3, wherein heat is exchanged in the exchanger. 5. The heating heat exchanger is installed at an outlet of a pressure vessel of a membrane module at any stage, and the intermediate concentrated water is heated to a desired temperature by the heating heat exchanger. The method for water treatment using the membrane module of two or more stages according to claim 1, wherein the water treatment is performed for 2 hours. 6. The membrane module according to claim 1, wherein a membrane module having a smaller amount of permeated water per membrane area at the same pressure and the same temperature is used as the downstream membrane module, as compared with the upstream membrane module. Water treatment method. 7. The treated water is pressurized and supplied to the first-stage membrane module by a pump to obtain permeated water from the permeated water outlet of the first-stage membrane module, and the intermediate concentration of the first-stage membrane module is obtained. In a water treatment method using one or more stages of membrane modules for obtaining intermediate concentrated water or concentrated water from an outlet of water or concentrated water, a heat recovery heat exchanger is used as an inlet part in a pressure vessel of the membrane module of any stage. A water treatment method using one or more stages of membrane modules, wherein the water to be treated or the intermediate concentrated water and the permeated water or the concentrated water are heat-exchanged in the heat recovery heat exchanger. 8. The water to be treated is pressurized and supplied to the first-stage membrane module by a pump to obtain permeated water from the permeate outlet of the first-stage membrane module, and the intermediate concentration of the first-stage membrane module is obtained. In a water treatment method using one or more stages of membrane modules for obtaining intermediate concentrated water or concentrated water from an outlet of water or concentrated water, a heat exchanger for heating is used as an inlet part in a pressure vessel of the membrane module of any stage. The water treatment method using one or more membrane modules, wherein the water to be treated or the intermediate concentrated water is heated to a desired temperature by the heat exchanger for heating. 9. The water to be treated is pressurized and supplied to the first-stage membrane module by a pump to obtain permeate from the permeate outlet of the first-stage membrane module, and the intermediate concentration of the first-stage membrane module is obtained. In a water treatment method using one or more membrane modules for obtaining intermediate concentrated water or concentrated water from an outlet of water or concentrated water, permeated water separated by the one or more membrane modules is treated water or intermediate concentrated water. A water treatment method using one or more membrane modules, characterized in that heat is exchanged with water in a heat recovery heat exchanger. 10. The heat recovery heat exchanger is installed at an inlet portion of a pressure vessel of a membrane module at any stage to treat water to be treated or intermediate concentrated water and permeated water for heat recovery. The water treatment method using one or more membrane modules according to claim 9, wherein heat is exchanged in the heat exchanger. 11. The heat recovery heat exchanger is installed at an outlet of a pressure vessel of a membrane module at any stage, and intermediate concentrated water and permeated water are collected in the heat recovery heat exchanger. 10. A water treatment method using one or more stages of membrane modules according to claim 9, wherein heat exchange is performed. 12. An inlet for treated water or intermediate concentrated water, one or more elements for membrane-treating the treated water or intermediate concentrated water to obtain permeate, a pressure vessel containing the element, and permeate. A water treatment device using a membrane module having an outlet and an intermediate concentrated water or an outlet for concentrated water in two or more stages, wherein an intermediate concentrated water outlet of an upstream membrane module and an intermediate concentrated water inlet of a downstream membrane module are provided. A water treatment apparatus comprising a heating heat exchanger for heating the intermediate concentrated water in the middle of the connected pipes. 13. A heat recovery heat exchanger that heats the water to be treated using concentrated water obtained in the water treatment device as a heat medium in the middle of a pipe for supplying the water to be treated. The water treatment device according to claim 12, wherein 14. Further, in the middle of a pipe connecting the intermediate concentrated water outlet of the upstream membrane module and the intermediate concentrated water inlet of the downstream membrane module, at the upstream side of the heating heat exchanger, the intermediate 13. The water treatment device according to claim 12, further comprising a heat recovery heat exchanger that heats the concentrated water using the concentrated water obtained by the water treatment device as a heat medium. 15. An inlet for treated water or intermediate concentrated water, one or more elements for membrane-treating the treated water or intermediate concentrated water to obtain permeate, a pressure vessel containing the element, and permeate. A water treatment device using a membrane module having an outlet and an intermediate concentrated water or an outlet for concentrated water in one or more stages, wherein the treated water is obtained in the water treatment device in the middle of a pipe for supplying the treated water. A water treatment device comprising a heat recovery heat exchanger for heating the permeated water as a heat medium. 16. An inlet for treated water or intermediate concentrated water, one or more elements for membrane-treating the treated water or intermediate concentrated water to obtain permeated water, a pressure vessel containing the element, and permeated water. A water treatment device using a membrane module having an outlet and an intermediate concentrated water or an outlet for concentrated water in one or more stages, wherein water to be treated or intermediate concentrated water is concentrated at an inlet or an outlet in the pressure vessel. A water treatment device comprising a membrane module provided with a heat recovery heat exchanger for exchanging heat with water or permeated water. 17. An inlet for treated water or intermediate concentrated water, one or more elements for membrane-treating the treated water or intermediate concentrated water to obtain permeate, a pressure vessel containing the element, and permeate. A water treatment device using a membrane module having an outlet and an intermediate concentrated water or an outlet for concentrated water in one or more stages, wherein water to be treated or intermediate concentrated water is desired at an inlet or an outlet in the pressure vessel. A water treatment apparatus comprising a membrane module having a heat exchanger for heating for heating to the temperature.