JP2002317980A - Method and apparatus for generating clean humid air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for generating clean humid air which contains no impurities. SOLUTION: The method for generating the clean humid air comprises the steps of generating hydrogen gas by contacting an alkali aqueous solution containing a metal hydrogen complex compound with a hydrogen generating catalyst, then mixing the hydrogen gas with an excess amount of an oxygen- containing gas such as air, and burning the mixture at a low temperature in the presence of an oxidation catalyst to generate the air containing a moisture. The apparatus for generating the clean humid air comprises a hydrogen generator having a storage container of the alkali aqueous solution containing the metal hydrogen complex compound and a hydrogen generating catalyst- containing box coupled to the container via a duct, an air intake port, and a wet air exhaust port. A low temperature burning unit having a hydrogen gas dispersing unit such as a gas dispersing plate or a jet nozzle tube, an oxidation catalyst carrying plate and a heating plate is coupled in series. A passage to introduce the hydrogen gas generated from the generator to the hydrogen gas dispersing unit is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for generating clean air in a wet state and a generator used for the method.

[0002]

2. Description of the Related Art In order to maintain the moisture in the air in a house or factory at a predetermined concentration, and to maintain normal human health and product quality,
Various moisturizing methods have been performed so far, for example, air is blown into heated water as desired, to generate air containing water, and a method of discharging it into a room, generating water by heating and boiling. There are proposed a method of discharging the steam into a room, a method of causing water in a spray state to come into contact with air in a countercurrent manner to generate air containing moisture, and releasing the air into the room.

However, in these moisturizing methods, since water and air obtained from the surrounding environment are usually used as they are, contaminants such as dust and germs contained therein, and carbon dioxide and carbon monoxide are contained therein. It is unavoidable that impurities such as nitrogen oxides and carbides are mixed in, and it is unsuitable especially when special care is required for hygiene such as hospitals and nursing homes.

On the other hand, the inventor of the present invention first dipped a wide endless belt made of non-woven fabric into a water tank, and allowed the air to pass through the endless belt while rotating to generate cooled moist air. (Japanese Utility Model Laid-Open No. 52-151671). According to this device, dust contained in the air is adsorbed on the nonwoven fabric and removed, and if a bactericide is added to the water tank, various bacteria contained in the water are also removed, but it is contained in the air. Since impurities such as carbon dioxide, carbon monoxide, nitrogen oxides and carbides cannot be removed, clean moist air cannot be obtained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a method and an apparatus for supplying clean moist air free of impurities by improving the disadvantages of the conventional method. It was made for the purpose.

[0006]

Means for Solving the Problems The present inventor has conducted various studies on metal hydride complex compounds, and when a solution prepared by dissolving the compound in an aqueous alkaline solution is brought into contact with a hydrogen generation catalyst, pure hydrogen containing no impurities is obtained. Is found, and if this hydrogen is mixed with an excess amount of air and burned at a low temperature in the presence of a catalyst, clean moist air can be obtained, and based on this finding, the present invention has been accomplished. Was.

That is, according to the present invention, an aqueous alkaline solution containing a metal hydride complex compound is brought into contact with a catalyst for hydrogen generation to generate hydrogen gas, and then an excess amount of an oxygen-containing gas such as air is mixed with the hydrogen gas. A method for generating clean moist air characterized by generating air containing moisture by burning the mixture at a low temperature in the presence of an oxidation catalyst, and a storage container for an alkaline aqueous solution containing a metal hydride complex compound, A hydrogen generator comprising a hydrogen-containing catalyst-containing box body connected by a pipe and a pipe, an air inlet and a humid air outlet, and a hydrogen gas disperser such as a gas dispersing plate or injection nozzle tube, and an oxidizing catalyst supporting plate. And a low-temperature combustion section consisting of a box containing a heating plate connected in series, and a pipe line for introducing hydrogen gas generated in the hydrogen generation section into the hydrogen gas disperser was provided. There is provided a wet air generating apparatus according to claim and.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a front view showing an example of an apparatus suitable for carrying out the method of the present invention, and FIG. 2 is a partially cut-away side view of the apparatus. Are connected in series. In these figures, the alkaline aqueous solution containing the metal hydride complex is
It is introduced into the liquid storage container 1 via the aqueous solution supply valve 2 and the pipe 3, and is continuously introduced into the hydrogen generator A via the flow control valve 4 and the pipe 5. The hydrogen generator A is a box 6
And an aqueous alkaline solution containing a metal-hydrogen complex compound introduced into the hydrogen generating section A, which is in contact with the hydrogen generating catalyst block 7 and generates hydrogen gas. .

Next, the generated hydrogen gas is sent to the low temperature combustion section B via the hydrogen gas supply pipe 8 and the gas amount adjusting valve 9. The low-temperature combustion section B is composed of a box 10 having an air inlet 11 and an outlet 12, in which a hydrogen gas header 13 and a hydrogen gas dispersion plate 1 connected to a pipe 8 are provided.
4. The oxidation catalyst supporting plate 15 and the heating plate 16 are housed. And the hydrogen gas introduced into the low temperature combustion part B is:
Here, the air is mixed with an excess amount of air introduced from the air inlet 11 and comes into contact with the catalyst supporting plate 15 for oxidation, and at the same time, the air is heated by the heating plate 16 to perform low-temperature combustion to generate water. The water thus generated is mixed with unreacted air as water vapor, that is, discharged from the air outlet 12 to the outside as wet air, and is used for replenishment of moisture.

In this case, a filter plate is provided between the hydrogen gas dispersion plate 14 and the oxidation catalyst support plate 15 in the low temperature combustion section B or between the oxidation catalyst support plate 15 and the heating plate 16, or If the body 16 itself is formed of a porous body, bacteria, mold, dust, pollen, and the like can be removed, so that cleaner moist air can be obtained.

In the method of the present invention, it is necessary to use a metal hydride complex compound as a material for generating hydrogen gas. Such metal hydrogen complex compound, for example, the general formula ^{_{M I M III H 4-n}} R n (I) or _{^{M II (M III H 4-}} n R n) 2 (II) ( wherein n 0 Or an integer of 1 to 3).

M ^{I in} these formulas is an alkali metal such as lithium, sodium, potassium, rubidium and the like, and M ^II is an alkaline earth metal such as magnesium,
Calcium, strontium or zinc, and M ^III is boron, aluminum or gallium.

R represents, for example, an alkyl group such as an ethyl group or a butyl group, a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, i
alkoxy or acetoxy groups such as so-butoxy group, sec-butoxy group, tert-butoxy group, 2-methoxyethoxy group, 2-ethoxymethoxy group,
An acyloxy group such as a propionyloxy group.

Accordingly, examples of the metal hydride complex compound represented by the general formula (I) include sodium borohydride (NaBH ₄ ) and lithium aluminum hydride (LiA
lH ₄ ), sodium trimethoxyborohydride NaB
H (OCH ₃ ), sodium triacetoxyborohydride NaBH (OCOCH ₃ ) ₃ , lithium triethylborohydride Li (C ₂ H ₅ ) ₃ BH, lithium tri-s-butylborohydride Li (s-C ₄ H _{9) 3} BH, hydride tributylboron lithium _{Li (n-C 4 H 9} ) 3 BH, hydrogenated tri -s- butylborohydride potassium _{K (s-C 4 H 9} )
₃ BH, lithium trimethoxy aluminum hydride Li
AlH (OCH ₃ ) ₃ , lithium monoethoxy aluminum hydride LiAlH ₃ (OC ₂ H ₅ ), tri-tert-
Lithium butoxy aluminum hydride, bis hydride (2
-Methoxyethoxy) aluminum sodium. Examples of the metal hydride complex represented by the general formula (II) include zinc borohydride Zn
(BH ₄ ) ₂ , calcium borohydride Ca (BH ₄ ) ₂ ,
Zinc tetramethoxyborohydride Zn [B (OCH ₃ ) ₂
H ₂ ] ₂ , calcium hexaethoxyborohydride Ca
[B (OC ₂ H ₅ ) ₃ H] _{2 and the} like. These metal hydride complexes are known and are commercially available as selective hydrogenation reagents.

In general, these metal-hydrogen complex compounds are those in which n is 1 to 3, that is, a part of hydrogen atoms is an alkyl group,
Those substituted with an alkoxyl group or an acyloxy group have lower reactivity than those not substituted, and can be used when controlling to reduce the amount of generated hydrogen.

In the present invention, the compound represented by the general formula (I) or (I)
The metal hydrogen complex compound represented by I) may be used alone or in combination of two or more. These metal-hydrogen complex compound, upon contact with water, the reaction formula ^{_{M I M III H 4-n}} R n + 2H 2 O → (4-n) H 2 + M
^I M ^III O ₂ + ^nRH or _{^{M II (M III H 4-}} n R n) 2 + 4H 2 O → 2 (4-n)
It reacts according to H ₂ + M ^II M ^III ₂ O ₄ + 2nRH (where M ^I , M ^II , M ^III , R and n have the same meaning as described above) to generate hydrogen.

The amount of hydrogen generated at this time is the sum of the amount of hydrogen generated by the decomposition of the metal hydride complex itself and the amount of hydrogen generated by the decomposition of water. It is very high, reaching for example 10.9% by weight when using sodium borohydride. In addition, there is an advantage that the hydrogen obtained in this manner is of high purity containing no impurities.

In the method of the present invention, in order to handle these metal hydride complex compounds in a stable state, it is necessary to use them as a solution dissolved in an aqueous alkaline solution. As the alkali, lithium hydroxide, sodium hydroxide,
Alkali metal hydroxides such as potassium hydroxide, and quaternary alkyl ammonium compounds such as tetramethylammonium hydroxide and tetraethylammonium hydroxide are used.

These alkalis are at least 5% by weight,
Preferably, it is used as an aqueous solution having a concentration of at least 10% by mass. The upper limit of the concentration is the saturated concentration of the alkali. However, if the concentration is too high, the metal hydride complex compound is difficult to dissolve. Therefore, it is preferable to select the concentration within the range of 30% by mass or less. For example, in the case of sodium hydroxide, 8 to 3
At a concentration of 0% by mass and potassium hydroxide in the range of 10 to 25% by mass, the metal hydride complex compound is well dissolved, and no generation of hydrogen is observed.

In this case, it is advantageous that the higher the concentration of the metal hydride complex compound, the larger the amount of hydrogen generated per volume. The solubility of a metal hydride complex in an alkaline medium changes as a function of temperature, and there is a significant difference between high and low temperatures. Although a phenomenon occurs, the solution in which a part of the metal hydride complex compound is precipitated does not cause any particular problem in the method of the present invention. In addition, 10 mass% sodium hydroxide aqueous solution 10
The solubility of NaBH ₄ in 0 g is 61 g, and the solubility of KBH ₄ in 100 g of a 10% by mass aqueous potassium hydroxide solution is 15 g. The aqueous alkali solution containing the metal hydride complex compound thus prepared is very stable and does not generate hydrogen even when stored for a long time.

If desired, an alcohol such as methyl alcohol or ethyl alcohol, or a water-miscible solvent such as dimethylformamide, dimethylacetamide, ethylene glycol or diethylene glycol may be added to the aqueous alkali solution containing the metal hydrogen complex compound. it can.

Next, examples of the hydrogen generating catalyst used for generating hydrogen gas by contacting with the above-mentioned alkali aqueous solution containing a metal hydrogen complex compound include nickel, cobalt, zirconium, rhodium, platinum, palladium, and the like.
Known catalysts for hydrogen generation such as silver and gold are used.

As the hydrogen generating catalyst, a so-called hydrogen storage alloy can be used. Such hydrogen storage alloys include, for example, Mg ₂ Ni alloy, Mg ₂ Ni
Mg ₂ Ni-based alloys and ZrN, such as a eutectic alloy of the Mg
Laves phase type AB ₂ type alloy such as i ₂ type alloy and TiNi ₂ type alloy, AB type alloy such as TiFe type alloy, LaNi ₅
AB ₅ type alloys, such as systems alloys, such as TiV ₂ alloy B
These can be arbitrarily selected from the CC type alloys, and may be used alone or as a mixture of two or more.

The performance of the catalyst for hydrogen generation can be remarkably improved by fluorination. This fluorination treatment is performed, for example, by immersing a metal or an alloy in an aqueous solution containing a fluorinating agent to form a metal or an alloy having a fluorinated surface.

The aqueous solution containing a fluorinating agent is usually
An aqueous solution containing fluorine ions and alkali ions is used. For example, an aqueous solution containing alkali fluoride at a concentration of about 0.2 to 20% by mass is added with hydrogen fluoride to adjust the pH to 2.0 to 6%. It can be prepared by adjusting to about 0.5. The alkali fluoride used at this time is not particularly limited, and those which are easily soluble in water, such as sodium fluoride, potassium fluoride, and ammonium fluoride, are preferable, and potassium fluoride is particularly preferable. These alkali fluorides may be used alone or in combination of two or more.

The preferred concentration of the alkali fluoride in the aqueous solution containing a fluorinating agent is 0.3 to 3% by mass in the case of sodium fluoride, 0.5 to 5% by mass in the case of potassium fluoride, and 0 in the case of ammonium fluoride. 0.5 to 8% by mass. If the concentration of the alkali fluoride is lower than the above range, it takes a long time to form the fluorinated surface, which is not practical, and if the concentration is higher than the above range, it is difficult to form a fluorinated surface of sufficient thickness. And the stabilizing effect becomes insufficient.

If the pH of the aqueous solution containing a fluorinating agent is less than 2.0, the metal fluorination reaction proceeds rapidly on the surface of the metal or alloy, so that it is difficult to form a uniform fluorinated surface, and 6.5. If it exceeds, the metal fluorination reaction rate becomes slow, and a fluorinated surface with a sufficient thickness cannot be formed. The preferred range of this pH is 4.5 to 6.0 in terms of having an appropriate metal fluorination reaction rate and forming a fluorinated surface with a uniform and sufficient thickness. The amount of hydrogen fluoride required to adjust the pH range is usually from 1 to 1 in the case of sodium fluoride per mole of alkali fluoride.
The range is 3 mol, 0.2 to 3 mol for potassium fluoride, and 0.2 to 1 mol for ammonium fluoride.

In order to form a fluorinated surface on a metal or an alloy using the aqueous solution containing a fluorinating agent, a metal or an alloy is immersed in the aqueous solution containing a fluorinating agent, and the fluorinated surface is usually subjected to 0 to 0 at normal pressure. At a temperature of the order of 80 ° C., preferably in the range of 30 to 60 ° C., a sufficient thickness on the surface, i.e.
Hold until a fluorinated surface of about 01 to 1 μm is formed. The time required for this is about 1 to 60 minutes.

In the method of the present invention, the above-mentioned catalyst for hydrogen generation is used in the form of particles, rods, plates, perforated plates or nets, but is easy to handle and has a large contact area. It is preferable to use it after forming it into a porous block.

The amount of hydrogen gas generated in the present invention, and thus the moisture content in the finally obtained humid air, is determined by the contact speed (area speed per unit time) between the aqueous alkali solution containing the metal-hydrogen complex compound and the catalyst for hydrogen generation. And passing speed (unit time,
It can be controlled by changing the mass or volume per unit area).

Next, examples of the oxidizing catalyst used at the time of low-temperature combustion in the method of the present invention include those commonly used as oxidizing catalysts, for example, noble metal catalysts such as platinum and palladium. These are preferably used by being supported in the form of a thin film on the surface of a foamed metal such as nickel or a nickel alloy.

This low-temperature combustion is carried out in the presence of a large excess of air with respect to the supplied hydrogen gas, for example, in the presence of air containing oxygen that is at least 5 mol times the oxygen that reacts with hydrogen to produce water, The reaction is carried out in the presence of air in a volume ratio of 5 times or more, preferably 10 times or more, generally 7 to 15 times.

The mechanism of the low-temperature combustion is such that hydrogen directly ejected from the nozzle and oxygen in the surrounding air cause a direct contact reaction on the surface of the catalyst carrier, so that 1 g of hydrogen produces 9 g of steam as a product. To generate 121 kJ of combustion heat.

In the low temperature combustion, since hydrogen and oxygen in the air come into direct contact with each other, CO ₂ or CO ₂ such as combustion containing hydrocarbons is used.
Does not occur, and naturally burns at a low temperature, so that nitrogen oxides, unlike flame combustion, do not occur.

Although the combustion heat of the low-temperature combustion can directly heat the air, it is usually mostly consumed for heating the catalyst carrier rather than for the surrounding air due to the difference in heat transfer.
Radiative heat transfer from the catalyst carrier is mainly involved. In order to efficiently receive the radiant heat from the catalyst carrier, a heating member formed of a porous material through which air can pass is provided so as to face the catalyst carrier, and the radiant transfer received from the catalyst carrier is provided. When air passes through a heating body heated by heat, it exerts a heat sterilization and disinfection effect while filtering microorganisms and the like in the air. This low-temperature combustion is performed by mixing hydrogen gas and air for 200 to 40 hours.
It is performed in the range of 0 ° C.

The heating element is made of aluminum capable of withstanding heat,
It may be formed of a porous material such as nickel or ceramics, and may have any shape, such as a honeycomb, a mesh, a foam, or a non-woven fabric mixture of material fibers, as long as it can exhibit filtration and sterilization effects. The surface of the heating element can be coated with titanium oxide or a photocatalyst to further impart a sterilizing effect.

As described above, according to the present invention, by combining the generation of hydrogen by the decomposition of the metal hydride complex and the low-temperature catalytic combustion of the hydrogen, fresh steam is generated and used for humidification. At the same time, heat sterilization of the entrained air can be performed to supply clean moist air.

[0038]

Next, the present invention will be described in more detail by way of examples.

EXAMPLE As a hydrogen generating catalyst block, a nickel foam (65 mm in length, 65 mm in width, 65 mm in height) having a porosity of 90% and having communication holes was coated with the surface of which was subjected to fluoridation treatment and Co reduction to be porous. As a medium, a dispersion groove with a stainless steel filter having a width of 65 mm and a height of 50 mm was provided below the porous medium. Prepare 5 blocks of this, about 30
Hydrogen capable of generating water vapor (moisture) corresponding to the humidification amount of 0 ml / h (8 tatami mats in a wooden Japanese room and 13 tatami mats in a prefabricated Western-style room based on the Japan Electrical Manufacturers' Association standard) could be generated.
The device part of the hydrogen supply source is a stainless steel container having a width of 350 mm, a depth of 100 mm, and a height of 500 mm.
The upper half part was an aqueous solution storage tank, and a solution insertion port and a solution discharge port were provided on the side wall. The lower half is a hydrogen generation container, contains 5 blocks of hydrogen generation catalyst, and has a hydrogen take-out pipe at the top, and a sheath heater for liquid temperature adjustment is installed in the lowermost dispersion groove of the block. . A solution fuel for hydrogen generation of an alkaline aqueous solution containing a metal hydride complex compound comprises:
An aqueous solution containing about 3% by weight of sodium borohydride (NaBH ₄ ) in 0% by weight of sodium hydroxide is prepared, and about 6 liters are stored. As a result, 37 g / h of hydrogen required to generate 300 ml / h of steam (moisture) could be generated.

The catalyst burner of the low-temperature combustion device comprises a catalyst carrier, a flashback prevention and heat insulating material, and a hydrogen gas supply plate.
As a catalyst carrier for the combustion reaction, a palladium catalyst was used, and a selmet (material: nickel) plate was used as the carrier. Prevention of flashback and heat insulation are made of a laminated body of ceramic wool and stainless steel mesh spacers, and on the back side, a gas with a number of hydrogen gas injection nozzles arranged to supply hydrogen gas to the catalyst. Supply plates are stacked.
A rectangular tubular manifold is formed at the lower end of a vertical flat space in which a backing plate is provided behind the gas supply plate, and a hydrogen gas supply pipe is connected to the manifold. Next, the catalyst was burned at a surface temperature of 290 to 325 ° C. using an excess air rate of 5 times or more with respect to a hydrogen supply of 37 g / h. In addition to the above-described catalyst burner, a ceramic air heater having a porosity of 98% is disposed so as to face the catalyst carrier, and ceramic wool and a stainless steel mesh are disposed for heat insulation and filtration. The low-temperature combustion unit is 350 mm wide, 100 mm deep, and 300 mm high.
Made of stainless steel, all of which were held in the frame.

[0041]

According to the present invention, it is possible to continuously supply clean humid air without accompanying impurities and to perform necessary humidification.

[Brief description of the drawings]

FIG. 1 is a front view of an example of the device of the present invention.

FIG. 2 is a partially cutaway side view of the same device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid storage container 2 Valve 3,5 Pipe line 4 Flow control valve 6,10 Box 7 Hydrogen generating catalyst block 8 Hydrogen gas supply pipe 9 Gas amount control valve 11 Air intake 12 Air outlet 13 Hydrogen gas header 14 Hydrogen gas dispersion plate 15 Oxidation catalyst support plate 16 Heating plate A Hydrogen generator B Low temperature combustion unit

Claims (2)

[Claims] An alkaline aqueous solution containing a metal hydrogen complex compound is brought into contact with a hydrogen generating catalyst to generate hydrogen gas, and then an excess amount of air is mixed with the hydrogen gas. A method for generating clean humid air, comprising generating air containing moisture by burning at a low temperature in the presence. 2. A storage container for an aqueous alkali solution containing a metal hydride complex compound, a hydrogen generation unit comprising a hydrogen-containing catalyst-containing box connected to the storage container by a pipe, and an air inlet and a humid air outlet. A pipe for connecting a low-temperature combustion unit composed of a box containing a hydrogen gas disperser, an oxidation catalyst supporting plate and a heating plate in series, and introducing hydrogen gas generated in a hydrogen generator into the hydrogen gas disperser A moist air generator characterized by having a path.