WO1994028706A1

WO1994028706A1 - Irrigation membrane material and irrigation method

Info

Publication number: WO1994028706A1
Application number: PCT/JP1994/000948
Authority: WO
Inventors: Masayoshi Shiraishi; Yoshihiko Hiraga; Masayuki Kobayashi
Original assignee: Shimizu Corporation; Kubota Corporation; Japan Gore-Tex Inc.
Priority date: 1993-06-10
Filing date: 1994-06-10
Publication date: 1994-12-22
Also published as: JPH0750939A; AU6936794A

Abstract

An irrigation membrane material comprising at least four overlaid elongate sheets comprising in turn an aqueous liquid impermeable material sheet (1), a hydrophobic porous material sheet (2), and water vapor impermeable material sheets (3, 4), wherein the long side portions of said four sheets are joined together to form three internal spaces consisting of the first space formed between the sheets (1 and 2) so as to supply aqueous liquid such as sea water thereinto, the second space formed between the sheets (2 and 3) so as to collect water vapor that has left the first space and permeated the sheet (2) for condensation and the third space formed between the sheets (3 and 4) so as to supply aqueous liquid whose temperature is lower than that of aqueous liquid supplied into said first space thereinto, and wherein an opening is formed in said second space to drain condensed water therefrom. This irrigation membrane material is disposed between ridges for use and it is preferable that it be disposed for use with the sheet (1) exposed to sunlight.

Description

Description Irrigation membrane material and irrigation method Technical field

The present invention relates to an irrigation membrane and an irrigation method. More specifically, the present invention relates to an irrigation membrane material for distilling an aqueous liquid containing salt and the like using solar heat and supplying the obtained demineralized water to plants, and an irrigation method using the same. Background art

Conventionally, a method of using a hydrophobic porous membrane to obtain demineralized water from salt water or the like based on the principle of membrane distillation has been proposed. As shown in Japanese Patent Publication No. Hei 31-17526, which is one of them, the warm salt water channel, the hydrophobic porous layer adjacent thereto, the cooling plate adjacent thereto, and the cooling water channel adjacent thereto There is a distillation apparatus in which a multi-layer structure consisting of is wound in a spiral shape and housed in a housing. This is formed by stacking a long partition wall material and a hydrophobic porous material, winding them in a spiral shape, housing them in a housing, and solidifying both ends with an adhesive. This means that it is virtually impossible to repair defective parts that occurred during the manufacture of this equipment, damage that occurred during use, or leaks.

In addition, as shown in Japanese Patent Application Laid-Open No. Sho 62-23636429, a hollow structure made of a water-absorbing porous material is buried in the soil, and warm saline is supplied inside the hollow structure. A method has been proposed in which water vapor is released into the soil through a hydrophobic porous material and supplied to plants. According to this method, when the temperature of the soil around the hollow structure buried in the soil rises and the temperature difference with the hot salt water disappears, the movement of water vapor no longer occurs and is released into the soil. Since thermal energy could not be recovered, the thermal efficiency had to be extremely poor. Disclosure of the invention

The present inventors have conducted intensive studies in order to solve the above-mentioned problems. A multilayer structure including three spaces of a warm salt water channel, a distilled water channel, and a cooling water channel, and four partition walls forming these spaces. Simple and efficient irrigation by laying the body directly on the furrow surface, directly heating the warm salt water channel by solar heat, extracting distilled water from the opening partly provided in the distilled water channel, and supplying it to plants The inventors have found that the present invention is possible, and have completed the present invention.

Thus, according to the present invention, the first sheet comprises at least an aqueous liquid impermeable material, and the second sheet located thereunder comprises at least a hydrophobic porous material. The third and fourth sheets below the second sheet are made of at least water vapor impermeable material. At least four long sheets are stacked on top of each other and A membrane material that joins the sides to form at least three internal spaces, and the first space formed between the first and second sheets is for supplying an aqueous liquid such as seawater. The second space formed between the second and third sheets is for collecting and condensing water vapor that has passed through the second sheet from the first space. The third space formed between the third and fourth sheets is an aqueous liquid supplied to the first space. An irrigation membrane material for supplying a liquid at a lower temperature and having an opening for discharging condensed water in the second space; and This is an irrigation method using the irrigation membrane material, wherein the irrigation membrane material is promptly placed in a state where the first sheet is exposed to sunlight, and an aqueous liquid such as seawater is supplied to the first space. Supply the water to the third space An irrigation method characterized by supplying a liquid at a temperature lower than the ionic liquid, draining condensed water from an opening in the second space, and supplying the water to plants. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of a membrane material for irrigation of the present invention.

FIG. 2 is a schematic diagram of another example of the irrigation membrane material of the present invention.

FIG. 3 is a diagram showing a state where the irrigation membrane material of the present invention is arranged on the ground surface.

4A and 4B are schematic diagrams showing spacers.

5A and 5B are schematic diagrams showing the development of the irrigation membrane material of the present invention.

6A and 6B are schematic plan views showing an embodiment in which the irrigation membrane material of the present invention is arranged in a ridge.

FIG. 7 is a diagram showing the laying of the irrigation membrane material of the example. BEST MODE FOR CARRYING OUT THE INVENTION

That is, the membrane material for irrigation of the present invention is obtained by vertically stacking at least four long sheet materials and joining their long sides to at least three internal spaces. To form Fig. 1 schematically shows this irrigation membrane. In Fig. 1, 1 is the first sheet, 2 is the second sheet, 3 is the third sheet, and 4 is the fourth sheet. , 1 1 is the first space, 1 2 is the second space, 13 is the third space, 5 is the opening from the second space 12 <J a o.

The first sheet forms a first space with the second sheet, and an aqueous liquid such as seawater is supplied to the first space. Therefore, the first sheet must not allow this aqueous liquid to escape and Those that do not transmit air are preferred. Examples of such a material include synthetic resin-rich sheets such as polyethylene, polypropylene, and polyvinyl chloride, and metal sheets such as stainless steel and titanium.

In one embodiment of the irrigation method of the present invention, it is preferable to use a solar heat-absorbing material for the first sheet. It is also possible to apply an absorbent paint or, in the case of a synthetic resin, knead a black pigment or the like. Alternatively, the first sheet may be a transparent or translucent sheet that transmits sunlight, and the second sheet may be black or the like so as to have solar heat absorption.

The second sheet is made of a hydrophobic porous material. Part of the aqueous liquid supplied to the first space permeates the second sheet as water vapor and moves to the second space. Therefore, the second sheet must be impermeable to aqueous liquids and permeable to water vapor. As such a hydrophobic porous material, a polyolefin such as polypropylene or polyethylene, or a fluororesin such as polyvinylidene fluoride or polytetrafluoroethylene is made porous by a stretching method or the like. Things. In particular, the stretched porous polyester trafluoroethylene described in Japanese Patent Publication No. 51-18991 is excellent in water vapor permeability and heat and chemical resistance, and can be suitably used for the purpose of the present invention. . Further, the hydrophobic porous sheet may be reinforced by laminating a net, a nonwoven fabric, or the like, and may be a polyurethane resin, a fluorine-based ion exchange resin, or a fluorine-containing resin. It may be combined with a solid layer made of a resin which is insoluble in an aqueous liquid such as a basic hydrophilic resin and is water vapor permeable, or may be used in combination.

The third sheet forms a second space with the second sheet. In the second space, the transition from the first space through the second sheet To condense the water vapor into water, the third sheet must not be permeable to condensed water.

The third sheet also forms a third space together with the fourth sheet. A liquid lower in temperature than the aqueous liquid supplied to the first space is supplied to the third space. Therefore, the third sheet must not be permeable to the distilled water generated in the second space or the cooling liquid flowing in the third space, and the fourth sheet must be permeable to the third space. It must not be permeable to liquid flowing through it. Further, it is desirable that the third sheet be easily cooled by the liquid in the third space, and thereby the condensation efficiency of the second space can be increased. From this point of view, it is necessary to consider the third sheet thermal conductivity and thickness.

From the above, as the third and fourth sheet materials, synthetic resin-rich sheets such as polyethylene, polypropylene, and polyvinyl chloride, metal sheets such as stainless steel and titanium, and composite materials thereof are used. No.

Known methods for joining the four sheets include a method using an adhesive and a method using heat fusion. When an adhesive is used, if the sheet is a resin having poor adhesion such as polyethylene or polypropylene, a pretreatment with a primer or the like is required. In the case of heat fusion, a fusion method using a heat shield heat roll is adopted.

As described above, three spaces are formed by four sheet materials. To maintain these spaces, it is necessary to accommodate spacing materials (spacers) in these spaces. Is preferred. As the material of the spacer, a synthetic resin such as polyethylene, polypropylene, or polyurethane, or a metal such as stainless steel or titanium is used. The shape only needs to be one that does not obstruct the flow of liquid in each space. However, the liquid flows in the flow path of the planar multilayer structure described above. When the liquid flows at a very high flow rate, that is, when a high pressure is applied, the planar multilayer structure expands and the cross section is circular. Become. This means that the second and third sheets bend and undulate, creating a pool of distilled water between the two sheets and reducing the cooling effect. Will be hindered. To prevent this, a very rigid material, that is, a material with high bending strength, is used for the sheet spacer, and the outer peripheral portion of the multilayer structure is reinforced with a material having higher rigidity. Method. As such a material, various metal plates or plastic plates having a thickness of about 1 to 10 mm are preferably used.

In addition, as an outlet for distilled water, the second space needs to form an opening. However, at the time of joining the above sheets, the second sheet and the third sheet are interposed. By forming a part that does not join partially, it can be used as an outlet for distilled water. Further, the distilled water outlet may be formed by sandwiching a small-diameter tube or an envelope-like tube between the second sheet and the third sheet.

As shown in the cross-sectional view of FIG. 2, at the joint between the third sheet 3 and the fourth sheet 4, a space is provided in the sheet length direction and the second space 12 is A connection hole 14 may be provided as an outlet for distilled water. The dimensions of the multi-layered membrane material formed as described above may be of any size for the purpose of producing desalinated water for irrigation using salt water such as seawater. The width per unit will be in the range of 0,1 to 1.0 Om and length of 5 to 100 m. Of course. It is possible to use these units by connecting them in series or in parallel, and it is also possible to use them in a vertical multi-tiered manner. The case where irrigation is performed using a multilayered membrane material will be described. Figure 3 is a cross-sectional view of the multilayered membrane material laid on the ground surface in the flow channel length direction. This multi-layered film material is arranged in the order of the first sheet 1, the second sheet 2, the third sheet 3, and the fourth sheet 4 in order from the side exposed to sunlight (upper side). First space, also from top to bottom

11, a second space 12, and a third space 13 are formed. A heated aqueous liquid containing a salt or the like is flowed into the first space 11 of the multilayer film material having the above-mentioned structure and installed, and the liquid flowing through the first space 11 is flowed into the third space 13. When the low-temperature cooling liquid flows, the first space 11 and the first space 11

Due to the temperature difference existing between the three spaces 13 and the resulting vapor pressure difference, the pores of the second sheet 2 which is a hydrophobic porous material are formed from the first space 11. Water vapor moves toward the second space 2. The water vapor that has moved to the second space 2 is cooled and condensed on the surface of the third sheet 3 into distilled water.

In order for such a phenomenon to occur stably, there must be a temperature difference, that is, a vapor pressure difference, in any part in the length direction of the multilayered film material.

One of the objects of the present invention is to perform irrigation using unsuitable water for irrigation as it is, such as seawater, groundwater containing a large amount of salt, river water, or wastewater containing metal ions. It is. As an example of a practical irrigation method using these waters, first, a liquid such as seawater is introduced into the third space 13 from A in Fig. 3 as a cooling liquid. As the liquid flows from A to B, the temperature gradually rises due to heat transfer from the first space 11. Next, the liquid removed from B is introduced into C. At this time, it is desirable to further heat the liquid using a heating device 15 such as a solar heat absorbing device. The liquid introduced from C generates steam in the second space 12 while flowing toward D, and the temperature gradually decreases to transfer heat to the third space 13. Always in each part Then, there will be a temperature difference between the third space 13 and the third space 13. In addition, when the first sheet 1 has solar heat absorbing properties, the liquid flowing in the first space 11 is further heated, and the third space 13 and the third space 13 are heated. Becomes more stable. At this time, the liquid flowing through the third space 13 is heated considerably by receiving heat from the first space 11. Conducting this heat into the ground through the fourth sheet 4 lowers the thermal efficiency, so it is preferable to make the fourth sheet 4 adiabatic. Examples of such heat insulating materials include expanded polyethylene and expanded polystyrene, and composite materials of these with polypropylene, polyethylene sheets, and metal sheets. By adopting such an operation method, it becomes possible to recover latent heat generated when water vapor condenses in the second space 12 and heat transferred from the first space 11 in the third space 13. In addition, since the heating between B and C can be minimized, a very heat-efficient distillation apparatus can be obtained.

In the second space 12, the water vapor that has moved from the first space 11 condenses into distilled water, and flows out of the partially formed opening to the outside. The distance between the openings may be appropriately selected according to the distance between the plants to be cultivated. It is also possible to supply distilled water directly from the opening to the root of the plant or the underground rhizosphere through a small-diameter tube, etc. It is possible to cope with various plant cultivation intervals. In addition, in order to make the amount of water uniform at each distilled water outlet, it is effective to form the water vapor condensation surface of the third sheet 3 with a hydrophilic material. Specifically, hydrophilic metal sheets, such as stainless steel and titanium, and hydrophobic materials, such as polypropylene and polyethylene, which have been hydrophilized on one side by a method such as corona discharge sputtering are listed. I can do it. For more strict control, a valve or the like can be attached to the outlet of the tube or the like.

As described above, a spacer can be arranged in each of the spaces 11 to 13, and the shape can be, for example, as shown in FIGS. 4A and 4B. .

That is, as shown in FIG. 4A, a rod-shaped portion defining the flow channel thickness and a net-shaped spacer consisting of a portion connecting these in the horizontal direction, and as shown in FIG. One consisting only of a head-like portion is exemplified.

Further, the membrane material for irrigation of the present invention is based on the above-described four-layer three-channel structure and further has a hydrophobic porous sheet below the fourth sheet 4 as shown in FIG. 5A. A fifth sheet 5 made of a water-impermeable material and a sixth sheet 6 made of a water-impermeable material are added to develop a six-layer five-channel structure, or furthermore, these four layers 3 It is also possible to use a channel structure or a six-layer, five-channel structure as a unit, and form a structure in which these are stacked in multiple stages. Fig. 5B shows a structure in which a four-layer three-channel structure is used as a unit and these are stacked in three stages. In addition, as a method of laying the multi-layer irrigation material of the present invention, as shown in FIG. 4A, it may be laid between all the ridges 21. However, since it becomes an obstacle when a person or a machine passes through the furrow 21 ', it is possible to lay every other between the furrows 21 as shown in Fig. 4B. 6A and 6B, 21 is a ridge or a plant, 22 is an irrigation membrane material of the present invention, 23 is a supply channel for seawater, 24 is a drain channel, and 25 is a heating device. .

Although the irrigation membrane material of the present invention has been devised to be used by placing it on the ground surface as described above, it can be buried in the ground for use. Example

Example 1

200 zm thick polypropylene sheet as the first, third and fourth sheets, stretched 80% porosity and 80% porosity as the second sheet Using a polytetrafluoroethylene sheet, a 10-cm wide, lm-long membrane material (effective area of sheet 2: 0.1 lm ² ) was prototyped. The first space and the third space of this membrane material are formed by accommodating a 4 mm thick polypropylene spacer net, and the production water outlet is formed between the second sheet and the third sheet. A three-tube polyethylene tube with an inner diameter of 1πιιη and an outer diameter of 2mm was sandwiched between both ends. Most of the sheet materials were joined by heat fusion, and the rest were joined with hot melt adhesive for polypropylene. The connection for hot and cold water was a 9.5 mm x 8.3 mm polypropylene pipe, which was joined to the end of the membrane material with a hot melt adhesive. For hot water, a 3.5 wt% NaC1 aqueous solution (electric conductivity 540,000 ^ S / cm) is heated in a water bath and circulated through a chemical pump, and tap water is used as cooling water. did. As a result, as shown below, it was possible to obtain high-quality water with stable removal of salt. It was confirmed from the electrical conductivity of the produced water that salt was removed.

Hot water inlet 5 3 ° C Produced water volume 4.2 2 1 / m ² «hr Hot water outlet 4 7 ° C Produced water electrical conductivity 20 SZ cm or less Cooling water inlet 19. C

Cooling water outlet 2 7 ° C

Water flow 4 8 1 / hr

Example 2

The first sheet of the multilayer film material prototyped in Example 1 was coated with black paint to make it solar-absorbing, flow rate under sunlight, water bath The conditions such as heating were evaluated in the same manner as in Example 1. The measurement results are shown below.

Hot water inlet 53 ° C Production water amount 4.6 3 1 / hr Hot water outlet 4.8 ° C Produced water electrical conductivity 20 / S Zcm Cooling water inlet 19 ° C

Cooling water outlet 2 8 ° C

Since the solar heat was absorbed in the first sheet, the temperature of the hot water outlet was higher than in Example 1 and, furthermore, the amount of produced water was also higher than in Example 1.

Comparative example

A tubular hollow structure with an outer diameter of 16 band was prototyped using the same expanded porous PTFE sheet as in Examples 1 and 2, and two lm X products were buried in a sandbox and allowed to pass hot water. I did it. A 35 wt% NaCl aqueous solution was heated to 50 ° C in a water bath and circulated in the tube by a pump.

The amount of water released and condensed into the sand was measured as the increase in the weight of the sand box, and the water production leveled off at about 15 minutes after the start of operation, and did not increase much thereafter. Comparing the amount of produced water with the same unit in Examples 1 and 2, it was 0.851 / hr · m ² , which was remarkably lower than in Examples 1 and 2.

Hot water inlet 53 ° C

Hot water outlet 4 9 ° C

Flow rate 501 / hr

Example 3

Actual plant cultivation was performed outdoors using the multilayer film material 31 produced in Example 2. As shown in Fig. 7, small-diameter tubes 32 were attached to a total of six production water outlets and placed at the base of pertussis 33 two weeks after germination. Introduced. The cultivation soil was 100% sand, and six perennials 33 were planted in the same manner as a control.

Hot water 34 and cooling water 35 were flowed, and the system was operated for 6 hours per day to produce water.The average water production per water outlet was 770 ml / hr (M a X. 850 ml, Min 560 ml) and were almost uniform. After cultivation for three more weeks, all six perennials grew steadily. On the other hand, in the control plot, no water was given, and during this time, there was no rain, etc., so that the plant died completely three days after the test started and withered one week later. Industrial applicability

ADVANTAGE OF THE INVENTION According to the membrane material for irrigation of this invention, it becomes possible to perform irrigation simply and efficiently using water which is unsuitable for irrigation as it is, such as seawater. In addition, since cooling water is used for hot water, the surroundings do not heat up due to the heat of hot water and the like, making membrane distillation difficult.Consecutive distillation and irrigation can be performed, and thermal efficiency is improved. I do. In addition, there is no need to bury irrigation membranes in the soil, making installation and repair easier.

Claims

The scope of the claims

1. The first sheet is composed of at least an aqueous liquid-impermeable material, and the second sheet below it is composed of at least a hydrophobic porous material and is located below the second sheet. The third sheet and the fourth sheet are made of at least a water vapor impervious material. At least four long sheets are stacked on each other, and their long sides are joined to form at least three sheets. A first space formed between the first and second sheets for supplying an aqueous liquid such as seawater; a second space and a third space formed between the first and second sheets; The second space formed between the sheets is for collecting and condensing the water vapor that has passed through the second sheet from the first space, and between the third and fourth sheets. The third space formed in the space supplies liquid at a lower temperature than the aqueous liquid supplied to the first space. That for is of, and irrigation film material in the second space, characterized in that the openings of the order to discharge the condensed water is formed.

2. The irrigation membrane material according to claim 1, wherein the first sheet is made of a solar heat absorbing material.

3. An irrigation method using the irrigation membrane material according to claim 1. The irrigation membrane material is arranged in a ridge in a state where the first sheet is exposed to sunlight, and the first space is provided. Supplying an aqueous liquid such as seawater to the third space, supplying a liquid having a lower temperature than the aqueous liquid to the third space, draining water condensed from an opening of the second space, and supplying the water to the plant. Irrigation method.

4. The irrigation method according to claim 3, wherein the first sheet is made of a solar heat absorbing material.