JPS581611B2 - dehumidification element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Conventionally, as a dehumidification element, a honeycomb structure made of a sheet made of asbestos fibers or the like and filled with a moisture absorbing material such as lithium chloride is known.

In this case, it has been proposed to treat the above-mentioned structures, which consist of sheets of asbestos fibers, at high temperatures of up to 500 DEG C. and then advantageously fill them with a hygroscopic material such as lithium chloride.

By the way, the present inventors have discovered that a mixed sheet as described below, which is made of fibers mainly composed of activated carbon fibers with excellent adsorption ability, is a carrier that can be filled with water-soluble hygroscopic salts extremely easily and efficiently. They have discovered that this is the case, and have arrived at the present invention.

The present invention is a dehumidifying element in which hygroscopic salts are supported on a structure in which a honeycomb-shaped continuous air passage is formed using a sheet material containing activated carbon fibers having an equilibrium adsorption amount of benzene of 300 .mu./g or more.

The activated carbon fiber used in the present invention has a benzene equilibrium adsorption amount of 300 mg/g or more, and is obtained by firing and activating the raw material fibers listed below.

For example, natural cellulose fibers such as cotton, linen, and ramie; pulp fibers obtained from wood, bamboo, and linters; recycled cellulose fibers such as viscose rayon, polynosik, and copper ammonia rayon; polyvinyl alcohol fibers; and acrylic fibers. After adding a flame retardant to raw material fibers such as fibers, polyamide fibers, phenol resin fibers, lignin fibers, pitch fibers, etc. as necessary, 4.
Heat treatment is performed at a temperature of 00°C or lower, followed by carbonization and activation at a temperature of 500°C or higher.

Carbonization/activation treatment is carried out at 500°C in an atmosphere containing 10 to 70% by volume of water vapor, carbon dioxide, ammonia, etc.
This is done by heating to a higher temperature.

In this case, a suitable activator may be included.

The activated carbon fiber used in the present invention has a benzene equilibrium adsorption amount of 3
It is necessary to have the property of 00■/g or more,
If it is less than this, the intended effect of promoting the filling of adsorbent salts into the mixed sheet will not be sufficient.

Further, it is preferable that the activated carbon fiber has a total pore volume of 0.1 cm 2 /g or more, and that pores with a radius of 100 A° or less account for 70% by volume or more of the total pore volume.

In the sheet containing activated carbon fibers of the present invention, short fiber bulbs can be mixed in addition to the activated carbon fibers, which can provide strength to the mixed sheet by intertwining with the activated carbon fibers.

It is more preferable to include short fiber pulp made of a thermoplastic polymer that can be partially melted by heating in a certain temperature range, as exemplified below.

Examples of such pulp include short fiber pulps such as polyethylene, polypropylene, polyacrylonitrile, and polyvinyl alcohol.

The mixing ratio of activated carbon fibers is preferably 30 to 90% by weight.

If the content of activated carbon fibers is less than 25% by weight, the adsorption of the resulting mixed sheet becomes too low, making it difficult to efficiently fill the mixed sheet with hygroscopic salts.

On the other hand, if the content is 95% by weight or more, the strength of the resulting mixed sheet decreases.

Note that the mixed sheet may also contain non-thermoplastic short fiber pulp such as glass fiber and wood pulp.

To obtain the mixed sheet, normal papermaking methods are applied.

In other words, when making paper using a wet method, paper stock containing activated carbon fibers, mixed fibers, and a small amount of other thickening additives as needed is processed using a conventional paper making steel, such as a circular screen or fourdrinier. After separating, dry it in a Yankee type or multi-barrel dryer.

When thermoplastic fibers such as those described above are mixed, a mixed sheet with even higher wet strength can be obtained by heat-treating with a roller or the like at a temperature that partially melts the thermoplastic fibers. It will be done.

On the other hand, a method of paper making using a dry method may also be applied.

Even in this case, if thermoplastic fibers are mixed, it is preferable to perform the above-mentioned partial melting treatment by heating after papermaking.

The preferable temperature range for the partial melting treatment of thermoplastic fibers varies depending on the fibers to be mixed, but for example, polyacrylonitrile pulp is 120-160°C, polypropylene pulp is 120-160°C, and polyethylene pulp is 80-160°C. 120°C, and 70 to 110°C for polyvinyl alcohol pulp.

A typical structure of the present invention in which a honeycomb-shaped continuous air passage is formed is produced by manufacturing corrugated poles made of corrugated sheets and flat sheets from the above-mentioned sheets, and stacking a plurality of these sheets, or
Alternatively, it may be rolled up into a cylindrical shape (Fig. 1).

In addition, the honeycomb structure used in the present invention may be made by joining cylindrical bodies 22 in place of the wave shape as shown in FIG. 2, or by converging a large number of cylinders or polygonal cylindrical bodies as shown in FIG. There is something configured to do this.

Further, as shown in FIG. 4, uneven sheets may be combined with each other to form a honeycomb structure.

If necessary, both ends of the structure are treated with resin and reinforced using a conventional method.

Next, the honeycomb structure is immersed in an aqueous solution of an adsorption material such as lithium chloride, lithium bromide, calcium chloride, or the like.

Alternatively, these aqueous solutions may be passed through the structure.

Filling with the desired hygroscopic salts can be completed within a very short contact time of several minutes or less.

Next, excess salt aqueous solution on the surface of the mixed sheet constituting the honeycomb structure is removed by, for example, centrifugal dehydration.

By these operations, the desired dehumidifying element can be obtained in which no solid salts are deposited on the mixed sheet.

When filling the honeycomb structure of the present invention with lithium chloride, the former is more effective than the latter when compared to the case where normal asbestos paper containing 13% organic fiber is directly filled with lithium chloride under the same operating conditions. It was found that the amount of lithium chloride filled per weight of the sheet reached 3 to 5 times.

In this way, a dehumidifying element filled with 10 to 75% by weight of water-soluble hygroscopic salts based on the weight of the mixed sheet is obtained.

This element can be used, for example, as an element for a regenerative dehumidifier.

In this case, a caning is provided with an inlet and an outlet for a fluid, such as air, to be dehumidified and a fluid, such as heated air, which serves to remove moisture absorbed by the device and regenerate its dehumidifying capacity. However, the exchanger is incorporated into a known rotatable device.

In this case, the element of the invention moves between the dehumidification zone and the regeneration zone.

The terms used in the present invention will be explained below.

Benzene equilibrium adsorption amount The equilibrium adsorption amount is measured according to JISK-1412.

JIS specifies benzene adsorption power (4), but the expression is changed to express it in mg/g.

However, 0.1 to 0.2 g of the sample is used.

EXAMPLE A paper stock liquid consisting of 70 parts of activated carbon fiber (benzene equilibrium adsorption amount: 450 ■/g) using cellulose fiber as a precursor and 30 parts of polyacrylonitrile pulp was made using a conventional paper machine with a paper weight of 50 g/g. A mixed paper of m2 was made, and then the polyacrylonitrile pulp was partially melted at 140° C. using a heating roller to obtain the desired mixed sheet.

This was made into a single corrugated board as shown in FIG. 5 (a=3.3 mm, b=1.4 mm) using a normal single corrugated board manufacturing apparatus.

Next, this single corrugated cardboard was rolled up into a cylindrical shape on a core having a diameter of 20 mm to form a shape having a diameter of 200 mm and a length of 200 mm.

In this case, the wave crest of the single ball and the portion in contact with the flat plate were adhered and fixed with a vinyl acetate adhesive.

Next, it was immersed for 2 minutes in an aqueous solution containing 40% lithium chloride, and then pulled up and dehydrated by centrifugal force to remove the excess lithium chloride aqueous solution on the surface of the mixed sheet.

The thus obtained exchanger was kept in an absolutely dry state and weighed, and it was confirmed that 72% of lithium chloride was filled with respect to the weight of the mixed sheet.

When this device was left in an atmosphere with an absolute humidity of 6 gr/Kg air, it exhibited a moisture absorption rate of 83% based on the weight of the device.

[Brief explanation of the drawing]

FIG. 1 shows the honeycomb structure used in the present invention, which is made of rolled up cardboard. FIG. 2 is a diagram showing the winding up of another structure. 3 and 4 are cross-sectional views of the honeycomb structure. FIG. 5 shows a single corrugated board used in the example.

Claims (1)

[Claims] 1. A dehumidifying element in which hygroscopic salts are supported on a structure in which a honeycomb-shaped continuous air passage is formed using a sheet material containing activated carbon fibers with an equilibrium adsorption amount of benzene of 300 mm/g or more.