JPH0459669A - Formed article for heat-exchanging use - Google Patents

Abstract

PURPOSE:To enable heat-exchange in high efficiency by forming a number of through holes opened on both surfaces of a formed material composed mainly of powder, etc., of modified vitreous blast-furnace slag and utilizing the moisture-absorption and desorption capability and the heat capacity of the formed material. CONSTITUTION:Powder of vitreous blast-furnace slag is modified with an alkaline aqueous solution by the glass-dissolution reaction and the hydration reaction. A number of small through holes are bored through a formed material composed mainly of the modified powder or xonotlite, etc., to connect both surfaces of the formed material with the holes. A plurality of the above formed materials 1 are stacked one upon another in such a manner as to form two groups having different directions of the opened small holes 2. For example, outer air is introduced into the formed material 1 from a surface and air in a room is delivered from another surface perpendicular to the first surface to effect the heat- exchange of the air flows.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heat exchange molded body used as the main body of a heat exchanger for gas such as air.

[Conventional technology]

The heat transfer walls of heat exchangers are usually made of a highly thermally conductive material such as copper or aluminum. By the way, when heat is exchanged between gases such as air, moisture and the like often condense on the heat transfer surface. As a result, paper has been evaluated for its hygroscopic properties, and paper is now being used as a heat transfer wall for heat exchangers for air, etc.

On the other hand, molded bodies mainly composed of calcium silicate compounds such as xonotlite are called artificial wood and are widely used as building materials. The manufacturing method is to first add water to a siliceous raw material and a calcareous raw material to form a mixed slurry, and then react at about 90°C to form a gel. Put this in an autoclave and heat it to 190~250°
C for several hours to synthesize xonotlite. Glass fibers, surfactants, polymer admixtures, etc. are appropriately added to this zonotrite slurry to improve toughness as necessary, the mixture is stirred, and the mixture is placed in a mold and subjected to pressure dehydration molding.
This is a method to obtain a molded body by drying at about 20"C (Cement/Concrete, No. 469. Mar, 19
86, P37-43).

Another known method is to add phosphoric acid such as hypophosphorous acid or phosphate such as aluminum phosphate as a binder to steel slag, pour it into a mold, and solidify and harden it at room temperature to form a molded body. There is. The surface of this molded body can be coated with EBC paint, glass coated, enamel coated, etc. (Japanese Patent Laid-Open No. 62-235845).

A method of modifying vitreous granulated blast furnace slag powder with an aqueous alkaline solution is already known (Japanese Unexamined Patent Publication No. 1252559), and the present inventors have already completed a molded body using this modified slag powder. (Patent Application No. 1337818)
. A polymer admixture is usually added to this molded body. The polymer admixture functions as a binder between surface-modified slag particles, and also functions to improve the processability, bending strength, and surface properties of the molded article. There are no known examples of using these as heat exchangers.

[Problem to be solved by the invention]

Paper has superior moisture absorption properties compared to inorganic fibers, synthetic fibers, textiles, etc., but its moisture absorption capacity is not sufficient when used as an air heat exchanger.

An object of the present invention is to solve this problem and provide a heat exchange molded body having a simple mechanism and high heat exchange ability.

[Means to solve the problem]

The present invention has been made to solve such problems, and it provides a powder obtained by modifying vitreous blast furnace slag powder with an alkaline aqueous solution through a glass dissolution reaction and a hydration reaction, or a molded article mainly made of xonotrite or the like. It was discovered that by providing a large number of through holes communicating the two sides of the molded body, the molded body is extremely suitable for heat exchange.

Slag (surface-modified slag) powder obtained by modifying vitreous blast furnace slag powder through a glass melting reaction and hydration reaction is produced by treating vitreous blast furnace slag powder with an alkaline aqueous solution. The surface is modified by causing a sum reaction. Its shape differs from that of xonotrite, in that it is spherical or like a bunch of grapes with overlapping spheres. The main hydration product is tobermorite or similar minerals. The raw material vitreous blast furnace slag may be granulated slag, granulated slag, or the like. The particle size should be fine, for example 400 in Blaine specific surface area.
0cffl/g or more, especially 8000 to 14000c/g
Appropriately is something of the order of g. In order to obtain particles having such a particle size, they can be pulverized using a pulverizer, classifier, etc., if necessary. The specific surface area of the raw material slag influences the physical properties of the lightweight molded article of the present invention, particularly the bulk specific gravity. The alkaline aqueous solution is preferably a caustic alkali solution such as caustic soda or caustic potash, and the concentration is preferably 0.5N or higher, particularly IN or higher. In practice, caustic soda is easy to use. A combination of alkalis is also effective. It is also effective to combine an appropriate amount of sodium carbonate with caustic soda. The treatment time varies depending on the treatment temperature, etc., but is 30 minutes or more, and is usually about 1 hour to 10 hours. In order to promote the reaction, the treatment temperature should be higher, and in practice it is about 90°C.

Alternatively, a hydrothermal reaction over 100°C may be used.

This alkali treatment causes a glass dissolution reaction and a hydrate formation reaction to occur on the surface of the glassy blast furnace slag particles. As a result, the slag surface becomes porous and the BET specific surface area becomes 2.
0 to b 40nf/g or more, more preferably 90 to 78 or more.

After alkali treatment, wash with water to remove the alkali before use. The manufacturing method of such surface-modified slag is described in
It is disclosed in Japanese Patent No. 7093 and Japanese Patent Application Laid-open No. 1-252559. This surface modified slag has 250 to 80
By heating and dehydrating at about 0°C, preferably about 450°C, depending on the initial state, for example,
BET specific area 100rd/g 0JJ) 120
It can be increased to about 140 ri'/g. At this time, it is important to select temperature and time conditions that will not cause sintering due to heating and dehydration. Use of this heated and dehydrated slag is preferable because specific strength and moisture absorption and desorption properties can be improved.

As a method for manufacturing a molded body whose main material is a powder obtained by modifying vitreous blast furnace slag powder with an alkaline aqueous solution through a glass dissolution reaction and a hydration reaction, this main material is press-molded singly, Alternatively, at least a polymer admixture or synthetic pulp and water may be added, kneaded, and pressure molded.

The polymer admixture is preferably one that adheres uniformly to the surface-modified slag particles, and various rubber latexes, synthetic resin emulsions, etc. can be used. Rubber latex includes, for example, natural rubber latex and styrene-butadiene copolymer,
Latex such as acrylonitrile-butadiene copolymer, chloroprene polymer, etc. Synthetic resin emulsions include, for example, ethylene-vinyl acetate copolymer, vinyl acetate polymer, acrylic acid ester polymer, vinylidene chloride polymer, vinyl chloride polymer, etc. It is an emulsion of The amount of the polymer admixture added is suitably about 3 to 20%, particularly about 5 to 10%, based on the weight ratio of solids to the surface-modified slag. If it is less than 3%, the improvement in strength and machinability will be insufficient, while if it exceeds 20%, a decrease in fire resistance will become a practical problem.

Synthetic pulp is a synthetic resin, mainly polyolefin, made into pulp by imparting hydrophilic properties, and includes polyethylene pulp, polypropylene pulp, and the like. A suitable weight ratio to the surface-modified slag is about 3 to 20%, particularly about 5 to 10%. If it is less than 3%, improvements in machinability and surface gloss will be insufficient, while if it exceeds 20%, fire resistance will decrease.

Only one of the polymer admixture and the synthetic pulp may be added, or both may be used in combination.

In order to increase the strength of the molded article, it is preferable to further add reinforcing fibers.

The reinforcing fibers include inorganic fibers such as glass fibers and carbon fibers, synthetic fibers, and natural fibers. Synthetic fibers include polyester fibers, polyethylene fibers, etc., and natural fibers include pulp, cotton, mineral fibers, etc. Among these, glass fiber is particularly preferred in terms of nonflammability and cost. The amount of reinforcing fibers added depends on the specific gravity of the fibers, but is suitably about 2 to 10% by weight relative to the surface-modified slag. If it is less than 2%, the reinforcing effect is not practically effective, while if it exceeds 10%, it becomes difficult to ensure uniform dispersion.

By adding a flocculant to the polymer admixture, the adsorption of the polymer admixture to the surface-modified slag can be increased, which improves drainage (dewatering) properties during the pressure molding process and also reduces leakage into waste water. It is possible to reduce the amount of organic matter that is produced, making it easier to treat wastewater.Although some flocculants are inorganic, such as aluminum sulfate, the molded product of the present invention uses organic flocculants, especially cationic ones. Polymer flocculants are preferred. Examples of cationic polymer flocculants include quaternary amine compounds such as polydialkylaminoalkyl acrylate, polyaminomethyl acrylamide, polyvinylpyridinium halogen salts, and polyvinylimidacillin. In the case of a cationic polymer flocculant, the amount added is 0.05 to 0 per 1 part by weight (solid weight) of the polymer admixture.
．． About 2 parts by weight is preferable.

Lightweight molded bodies also contain lightweight aggregates, thickeners, dispersants,
It can further contain pigments, acicular or fibrous calcium silicate hydrate, hydraulic plaster, and the like. The lightweight aggregates are pearlite, shirasu balloons, etc., and if the amount added exceeds 60% by weight relative to the surface-modified slag, the strength, workability, etc. of the molded product will decrease, which is not preferable. The thickener improves the dispersibility of reinforcing fibers and ensures shape retention during molding, and water-soluble polymers, such as cellulose ethers, are used for boat fishing. The dispersant is added to disperse polymer admixtures, reinforcing fibers, etc., and to improve the fluidity of the kneaded slurry, and includes naphthalene sulfonate formalin high condensates, melamine sulfonic acid compounds, and the like. Pigments are used to color molded objects, and include white lead, red lead,
Inorganic pigments such as yellow lead, ultramarine blue, navy blue, cobalt oxide, titanium dioxide, titanium yellow, red iron black, iron black, molybdenum red, litharge, and aluminum powder, and organic pigments such as Ab-based and phthalocyanine-based pigments can be used. Calcium silicate hydrate is obtained by adding water to a siliceous raw material and a calcareous raw material and causing a heating reaction, and acicular or fibrous crystalline ones such as xonotlite and tobermorite are preferable.

The weight ratio of the surface-modified slag to the above calcium silicate hydrate is suitably in the range of 9:1 to 1:9, preferably 7:3 to 3. The hydraulic plaster may be any of α-type and β-type hemihydrate stones, anhydrite stones, etc., but from the viewpoint of cost, baked stone plaster containing β-type hemihydrate stones as a main component is preferable.

The amount of gypsum added is 1 in weight ratio to the surface-modified slag.
A suitable range is about 0 to 150%, preferably about 30 to 70%. If it is less than 10%, the effect of improving bending strength is small;
On the other hand, if it exceeds 150%, machinability and specific strength decrease. If necessary, a setting regulator for gypsum, such as sodium citrate, can be further added.

As a method of forming a compact, surface-modified slag powder (
(or a slurry containing the same), hydraulic plaster, a polymer admixture, etc., and a mixture containing water are first kneaded. When reinforcing fibers, flocculants, synthetic pulp, calcium silicate hydrate, lightweight aggregates, thickeners, dispersants, pigments, etc. are added, they are added before or during kneading. If there is a risk that air bubbles may be mixed into the kneaded slurry and cause defects in the molded product, an antifoaming agent may be added or defoaming may be carried out under reduced pressure during or after kneading. The slurry molding method may be selected depending on the purpose and use of the final product, such as pressurization, paper forming, extrusion, and depressurization.
A method of dehydrating and molding a slurry obtained by kneading under pressure is often used. In this case, the slurry is usually poured into a mold such as a formwork and pressurized, but in order to improve uniform dehydration and molding efficiency, wire mesh, filter paper, filter cloth, perforated plates, etc. are used on the pressurizing surface, and vacuum dehydration and A unit capable of defoaming can be incorporated, and an embossed plate can be incorporated to improve the design of the surface. Further, the molded product after pressure dehydration can be cut into a predetermined shape. Pressure may be applied at a pressure that allows dehydration to a predetermined level, for example, the bulk specific gravity of the molded product may be adjusted to a predetermined value, usually 10 to 1.
00kgf/cm2, preferably 20-60kgf/c
It is rA. Furthermore, the optimum water content in extrusion molding is different from that in pressure molding. When molding using a papermaking method, it is important to note that the key points of the technology will change depending on the molding method selected, such as the need to devise ways to stably incorporate (fix) additives such as polymer admixtures into the molded product.

Drying should be performed to the extent that moisture inside the molded body can be removed and crystallization water of the surface-modified slag remains, for example, 100 to 180%.
It may be dried by heating at about 110 to 150°C, preferably about 110 to 150°C. In order to prevent the molded product from cracking due to drying, it is also preferable to first pre-dry it at about 60 to 80°C. The lightweight molded product obtained in this way has a composition obtained by removing water from the kneaded material, and has a bulk specific gravity of 0.2 to 1 g/
It is a porous body of approximately 0.4 to 0.6 g/ci, preferably approximately 0.4 to 0.6 g/ci.

In addition, the surface-modified slag powder can also be press-molded by itself.

Various methods for producing molded bodies based on xonotlite are known, and the molded body of the present invention can also be manufactured using these methods. Generally, in this method, water is first added to a siliceous raw material and a calcareous raw material to form a mixed slurry, and the mixture is first reacted at about 90°C to form a gel. This is placed in an autoclave and reacted at 190 to 250°C for several hours to synthesize xonotlite. Glass fibers, surfactants, polymer admixtures, etc. are added to this xonotrite slurry as necessary to improve toughness, and the mixture is stirred.
This is a method to obtain a molded product by placing it in a mold, dehydrating it under pressure, and drying it at around 120°C (Cement/Concrete, N [1469, Mar, 1986. P37-4)
3).

Zonotlite is a type of calcium silicate hydrate, and C
The aO/SiO□ molar ratio is approximately 1. The crystal system of xonotrite is generally a pseudoorthorhombic lattice (a = 17.17 people, b
= 3.69 people, c = 6.96 people, β = 89.6°) and the compositional formula is Cab (S iho 17) (OH)z. The crystal structure is characterized by having a fibrous form in which the length direction extends along the b-axis. Further, the BET specific surface area of the xonotrite particles is about 25 to 30 rr (/g).

There are various patent applications regarding the manufacturing method of this molded body.For example, Japanese Patent Application Laid-open No. 52-15516 discloses an aqueous solution of calcium silicate by mixing powdered siliceous raw materials and calcareous raw materials in water and causing a heating reaction. A method is disclosed in which a slurry is obtained and a polymer emulsion is added thereto to adsorb the polymer onto calcium silicate. In addition, JP-A-54-160428 discloses that calcium silicate obtained by hydrothermally synthesizing a calcareous raw material and a silicic raw material is treated with hydraulic gypsum, a polymer emulsion, and a flocculant for polymer emulsions. In addition, a method is disclosed in which an aqueous slurry is prepared, which is then molded and dried to form a molded product.

JP-A-60-246251 discloses a styrene-butadiene copolymer latex containing carboxyl groups in calcium silicate obtained by hydrothermally synthesizing a calcareous raw material and a silicic raw material, and a cationic polymer flocculant. Disclosed is a method in which an aqueous slurry is formed by adding the following ingredients to form an aqueous slurry, which is then molded and dried to form a molded product. JP-A-63-85038 discloses that water is added to a mixture of lime raw materials and silicate raw materials to form a slurry, the slurry is heated with stirring in an autoclave to produce a calcium silicate crystal slurry, and synthetic pulp is added to this slurry. Or, a method is disclosed in which a thermally deformed product thereof is added, dehydrated, molded, and dried to obtain a molded product. Unexamined Japanese Patent Publication 1986
-201050 Publication describes a calcium silicate slurry obtained by mixing limestone raw material powder and silicic acid raw material powder, adding water and causing a hydrothermal reaction, and adding Seviolite and reinforcing fibers adsorbed with a polymer emulsion and pressing the mixture. A method for obtaining a molded body by dehydration molding and drying is disclosed. Furthermore, JP-A No. 63-260847 discloses a styrene-butadiene copolymer latex containing carboxyl groups in calcium silicate hydrate obtained by hydrothermally synthesizing a coalaceous raw material and a siliceous raw material. Disclosed is a method in which an aqueous slurry is prepared, which is then molded and dried to form a molded product, in which the molded product is reinforced with a fiber network. The molded article of the present invention can also be manufactured using these methods.

The molded product of the present invention usually has a plate shape and is used in a stacked manner. Appropriate thickness is about 5 to 40 mm.

The shape of the plate is usually square or rectangular, but other shapes such as hexagonal are also possible. On the other hand, it is also possible to provide through holes in two directions in one molded body, and in that case, the molded body can be made thick.

The through pores communicate the two sides of the molded body. These two sides may be either side, but usually two sides facing each other are used for convenience of manufacture and use. The diameter and number of pores are set so that the gas flow resistance is small and the contact area between the gas and the molded body is large.

The pore diameter is usually about 0.5 to 20 mm, and the number of pores may be determined so that the sum of the pore cross-sectional areas is about 10 to 80% of the total cross-sectional area of the molded body. Furthermore, the shape of the hole may be polygonal, such as a triangle, other than a circle.

Although it is convenient to form the through pores at the same time as the molded body is manufactured, it is also possible to form the through pores later in the manufactured molded body. As a method for forming a molded body during production, there is a method of extrusion molding.

In this extrusion molding method, in addition to directly forming pores, lost wax or other materials that can be removed by heating or cutting are extruded to fill the areas corresponding to the pores, and this material is then melted. There is also a method of forming by removing by means such as elution.

Molded bodies having through-pores are usually used in a form in which the side where the pores communicate is divided into two groups. For these two groups, it is sufficient that the gas inlet and outlet are divided into two groups. When the molded body is a fuselage, the layers are usually alternately laminated. The plates may be bonded together if necessary. The molded article of the present invention can be used by switching between the air inlet side and the air outlet side for each appropriate period of use.

[Function] Heat exchange using the molded article of the present invention utilizes its large moisture absorption and desorption ability and heat capacity. In other words, the heat of vaporization and heat of condensation generated by this moisture absorption and release is utilized. Generally, in the winter, the outside air is low and dry, while the inside of the room is hot due to heating and has higher humidity than the outside air due to human habitation. On the other hand, in the summer, the outside air is hot and humid, while the indoor air is cool and dry due to air conditioning. These states of the molded article of the present invention are utilized to efficiently exchange heat. To explain this in the winter, when warm, humid air from the room passes through the pores, it is cooled and condenses water, giving the heat of condensation to the molded body. The condensed water is absorbed and accumulated in the molded body. on the other hand,
When the cold (dry) air from the outside air passes through the through pores, it receives the above-mentioned absorbed moisture and becomes more humid, and the heat required to vaporize the moisture is received through the molded body.Heat exchange takes place in this way. , which allows for indoor ventilation with less heat loss.

The latent heat of condensation is the heat released when water vapor undergoes a phase change to water, and has a large amount of heat of 583 Kcal/kg.

Since the above-mentioned molded product is capable of adsorbing or releasing humidity of 10 to 20% of its weight, its performance is further improved by providing through-pores.

For example, the prerequisites are 25°C/60% RH indoors, 5°C/50% RH outdoors? In the case of H, 61% of heat can be recovered by using a molded body using surface-modified slag as a heat exchanger, and 55% of heat can be recovered with a xonotrite-based molded body, but conventional paper, only 37%
It is only the recovery rate of

〔Example〕

Glassy blast furnace slag (Nippon Kokan Keihin Steel fracture, granulated blast furnace slag) was milled using a ball mill with a Blaine specific surface area of 4500 cr.
The material was crushed to A/g and classified using an air classifier as a raw material for classification, resulting in a Blaine specific surface area of 14,000 cyft/g.
A fine powder slag was obtained.

This fine powder slag was added at a rate of 5 g to 100 Id of NaOH solution at a temperature of 90°C and a concentration of 3N.
BET specific surface area 100%/
g of surface-modified slag was obtained. This surface-modified slag was thoroughly washed with water to remove alkaline content, dried, and used as a raw material for producing molded bodies.

100 parts by weight of surface-modified slag powder, 10 parts by weight of styrene-phtadiene copolymer latex as a solid content, 3 parts by weight of methyl cellulose, 5 parts by weight of E-glass fiber, and 190 parts by weight of water.
Parts by weight were kneaded. This kneaded material was extruded to form a 60°
The product was dried at C for 15 hours and at 110°C for 5 hours to obtain a 200mm x 200mm x 10mm molded body, which had a large number of through pores with a diameter of 2mm communicating between a pair of opposing surfaces, spaced at 4-hole intervals. Ta.

Six of the molded bodies 1 were stacked with the through-holes 2 arranged in alternate directions to obtain a laminate as shown in FIG. 1.

This laminate was placed in the center of the heat exchanger shown in FIG.

Partition plates 3 are installed diagonally from all four corners of the laminate.
It was divided by setting up. The room was ventilated by sending air in the direction shown by the arrow in FIG. 2 using two fans (not shown). The left side and lower side of FIG. 2 are connected to the indoor air, and the right side and upper side are connected to the outside air.

A heat exchanger that exhausts air from the room when ventilation is performed using this heat exchanger when the indoor temperature and humidity are controlled at a constant temperature of 25°C and 60% RH, and the outside air is 5°C and 50% RH. The air on the exit side is 12°C and 80% RH, while the air on the exit side of the heat exchanger, which is brought in from the outside, is 17"C and 70% RH.
It was H.

When a xonotlite-based molded body was similarly prepared and used for indoor ventilation, it was still able to ventilate with a high heat exchange rate, although it was inferior to the above-mentioned molded body.

〔Effect of the invention〕

The molded article of the present invention enables efficient heat exchange with a simple mechanism, and allows ventilation to be performed with less energy loss.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a laminate of molded bodies according to an embodiment of the present invention, and FIG. 2 is a plan view illustrating the state in which this laminate is installed and used in a heat exchanger. Outside of Figure 1 and Figure 2

Claims (2)

[Claims] (1) In a powder obtained by modifying vitreous blast furnace slag powder with an alkaline aqueous solution through a glass melting reaction and a hydration reaction, or in a molded article whose main material is xonotrite, etc.
A molded body for heat exchange that has many through holes that communicate between two sides. (2) A molded body for heat exchange, in which a plurality of molded bodies according to claim (1) are stacked so that the side where the pores communicate are divided into two groups.