JP4918255B2 - Nitrogen gas generator - Google Patents

Description

  The present invention relates to a nitrogen gas generator capable of generating nitrogen-rich gas with an inexpensive and simple system.

  In recent years, in the fields of electronics / semiconductors, chemistry, metals, and foods, nitrogen is frequently used as an inert gas for the purpose of preventing oxidation. When nitrogen is used for these purposes, generally, a high-pressure nitrogen cylinder, a PSA (Pressure Swing Adsorption) type, or a hollow fiber membrane type nitrogen gas generator is used (for example, a special-purpose nitrogen supply unit). (Kaihei 7-183040). However, such a cylinder or apparatus has a problem that the weight and volume are very large, and the system becomes large. In particular, the PSA type or hollow fiber membrane type nitrogen gas generator needs to increase the pressure of the supplied air to about 0.5 MPa. Therefore, if a compressor is installed, a large amount of power is consumed and noise is also generated. is there.

In order to further purify the nitrogen-rich gas having a low oxygen concentration obtained by passing through the hollow fiber membrane, it has been proposed to absorb oxygen in the nitrogen-rich gas using iron powder (Japanese Patent Laid-Open No. 2003). -119090). However, in this method, it is necessary to obtain a nitrogen-rich gas using a hollow fiber membrane before removing oxygen with iron powder, and thus the above-described problems such as an increase in size and a large amount of power consumption have not been solved.
Japanese Patent Laid-Open No. 7-183040 JP 2003-119209 A

  In view of the above problems, an object of the present invention is to provide a light, compact and inexpensive nitrogen gas generator.

In order to achieve the above object, a nitrogen gas generator according to the present invention comprises a cartridge containing an oxygen absorbent that combines with oxygen in air to remove oxygen from the air and generate a nitrogen-rich gas; air comprises a introduction portion for introducing into the said cartridge without heating from the atmosphere, Ri detachably der the cartridge relative to the inlet portion, the oxygen absorbing agent is first At least one metal selected from the second group consisting of iron or iron oxide as a metal and titanium, zirconium, vanadium, niobium, chromium, molybdenum, aluminum, gallium, magnesium, scandium, nickel, copper, and neodymium, or rhodium And at least one metal selected from the third group consisting of iridium, ruthenium, palladium and platinum, It is characterized in that one prepared by the law.

  The PSA type or hollow fiber membrane type nitrogen gas generator requires a compressor for increasing the pressure of air, and there are problems in terms of cost, size, power, and noise. Since the oxidation reaction of the agent proceeds at atmospheric pressure, it is not necessary to increase the pressure to a high pressure, and thus high concentration of nitrogen can be generated only with an oxygen absorbent at a light weight, compact and inexpensive. In addition, by filling the detachable compact cartridge with the oxygen absorbent, the used and deteriorated oxygen absorbent can be replaced with a new cartridge. If a large amount of nitrogen is required, it is sufficient to have a large number of compact replacement cartridges.

In addition, the first group of metals consisting of iron (Fe), magnesium (Mg), gallium (Ga), germanium (Ge), cerium (Ce), tin (Sn), and indium (In) is caused by oxygen in the air. compared to other metal oxide, to form a high-valence metal oxide with a fast rate of oxidation, the nitrogen concentration of 95% or more, preferably capable of producing more than 98% of the nitrogen-rich gas . The first group of metals is also excellent in durability against repeated redox. Among these, iron and iron oxide (Fe, FeO, Fe ₃ O ₄ ) are safe, easy to control, and very inexpensive because the reaction proceeds with oxygen in the air at an appropriate rate. It is. The reaction of iron and iron oxide with oxygen is shown below.

Fe + 3 / 4O ₂ → 1 / 2Fe ₂ O ₃
FeO + 1 / 4O ₂ → 1 / 2Fe ₂ O ₃
Fe ₃ O ₄ + 1 / 4O ₂ → 3/2 Fe ₂ O ₃
Fe + 1 / 2O ₂ → FeO
Fe + 2 / 3O ₂ → 1 / 3Fe ₃ O ₄
FeO + 1 / 6O ₂ → 1 / 3Fe ₃ O ₄

  In addition, these reactions can be performed at -20 ° C to 300 ° C. The oxygen absorbent combined with oxygen can be combined with oxygen in the air again by reducing with a reducing agent such as hydrogen or hydrocarbons (for example, methane, propane, butane) and can be regenerated. Material.

Further, by adding the second group metal, particle growth due to sintering during the reduction reaction / air oxidation reaction of the first group metal such as iron can be suppressed, and the decrease in oxygen absorption efficiency can be suppressed. .

The oxygen absorbing agent, or with instead the metal of the second group, by further adding at least one metal selected from the third group, more rapidly oxidized at room temperature a metal of the first group of iron can do.

Further, when water introduced as a raw material contains water vapor, hydrogen may be generated by the reaction of the water vapor and the oxygen absorbent (Fe + 4 / 3H ₂ O → 4 / 3H ₂ + 1 / 3Fe ₃ O _4). ). If this hydrogen is mixed with nitrogen gas and discharged, not only will the concentration of nitrogen gas be reduced, but there is also a risk of explosion, but at least one metal selected from the second group and the third group is further added. By being added, it also acts as a catalyst for burning hydrogen and residual oxygen in the air (H ₂ + 1 / 2O ₂ → H ₂ O), and can be discharged as water vapor. In addition, carbon dioxide in the air may react with the oxygen absorbent to generate carbon monoxide (Fe + CO ₂ → FeO + CO), but at least one metal selected from the second group and the third group is In addition, oxygen in the air can be selectively reacted to suppress the generation of CO (CO + 1 / 2O ₂ → CO ₂ ).

  The nitrogen gas generator according to the present invention preferably further includes a cooling means for cooling the cartridge in order to lower the internal temperature of the cartridge. The nitrogen gas generator according to the present invention preferably further includes a heat insulating means for insulating the cartridge from outside air in order to maintain the internal temperature of the cartridge.

As described above, when water introduced as a raw material contains water vapor, the water vapor and the oxygen absorbent react to generate hydrogen. In this case, a method of adsorbing water vapor using silica gel or the like and introducing dry air is conceivable. However, even when water vapor is contained, hydrogen from water vapor can be obtained by appropriately adjusting the temperature of the cartridge. Can be suppressed. That is, the oxygen absorbent and oxygen in the air can be selectively reacted. In addition, about 300 ppm of carbon dioxide is contained in the air, and this carbon dioxide and the oxygen absorbent may react to generate carbon monoxide (Fe + CO ₂ → FeO + CO). Similarly, by appropriately adjusting the temperature of the cartridge, oxygen in the air can be selectively reacted to suppress the generation of CO.

  Thus, according to the present invention, a light, compact and inexpensive nitrogen gas generator can be provided.

  An embodiment of a nitrogen gas generator according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing the appearance of an embodiment of a nitrogen gas generator according to the present invention. FIG. 2 is a schematic diagram showing the configuration of an embodiment of the nitrogen gas generator according to the present invention.

  As shown in FIG. 1A, the nitrogen gas generator 10 includes a cartridge 11 filled with an oxygen absorbent and an air pump (illustrated) for introducing air from the atmosphere into the cartridge 11. The main body 12 is mainly composed. Both the cartridge 11 and the main body 12 have a cylindrical shape, but the cartridge 11 has a smaller diameter. Pipes 14 for introducing or discharging air or nitrogen gas are provided at both ends of the cartridge 11. As shown in FIG. 2, these pipes 14 are provided with a valve 15 for blocking the inside of the cartridge 12 from the outside air.

  One end of the cartridge 11 and one end 13 of the main body 12 are detachably connected by a screw-type structure. The pipe 14a connected to the main body 12 is configured such that the valve 15a is opened when the main body 12 is screwed and connected. The other pipe 14 b can open the valve 15 b by rotating the knob 16. Thereby, air can be introduced into the cartridge 11 and the nitrogen-rich gas generated in the cartridge 11 can be discharged.

  As shown in FIG. 2A, the introduction of air into the cartridge 11 is performed by sucking air from the atmosphere with an air pump in the main body 12 and introducing the air into the cartridge 11 through the pipe 14a. Thereby, the nitrogen rich gas produced | generated in the cartridge 11 can be discharged | emitted from the piping 14b. However, the present invention is not limited to this, as shown in FIG. 2B, the nitrogen rich gas generated in the cartridge 11 is sucked through the pipe 14a by the air pump in the main body 12, and thereby the inside of the cartridge 11 is drawn through the pipe 14b. It is also possible to introduce air into the.

The cartridge 11 is filled with an oxygen absorbent. The oxygen absorbent is mainly composed of at least one metal selected from the first group consisting of Fe, Mg, Ga, Ge, Ce, Sn, and In or a compound thereof. The compound is not particularly limited as long as it is a compound with oxygen, but an oxide, particularly a low valence oxide is preferable. Of the first group of metals, Fe is particularly preferable. As the oxygen absorbent mainly composed of Fe, for example, cast iron powder, reduced iron powder, electrolytic iron powder, atomized iron powder, and iron powder by a wet precipitation method can be used. These iron powders have a BET specific surface area of 0.1 to 70 m ² / g, preferably 1 to 50 m ² / g, and an average particle size of 0.01 μm to 5 mm, preferably 0.05 μm to 1 mm. Although it can be used in the form of particles, it is preferably in a shape suitable for reaction such as a pellet shape, a cylindrical shape, a honeycomb structure, and a nonwoven fabric shape.

  Further, in order to reduce and regenerate the iron oxide once combined with oxygen and increase the oxidation efficiency when combining with oxygen again, Ti, Zr, V, Nb, Cr, Mo, Al, Ga, Mg, Sc, In order to keep the impurity gas concentration of at least one metal selected from the second group consisting of Ni, Cu and Nd, or hydrogen or carbon monoxide low, the third group consisting of Rh, Ir, Ru, Pd and Pt It is preferable to add at least one metal selected from Among these, Mo and Al are more preferable as the second group, and Rh and Ir are more preferable as the third group. Further, at least two kinds of metals selected at least one from each of the second group and the third group can be added.

  As for the compounding ratio of the metal to add, 0.1-30 mol% is preferable and 0.5-15 mol% is more preferable when all the metals are 100 mol%. When the blending ratio is less than 0.1 mol%, the effect of improving the oxidation effect is not recognized. On the other hand, if it exceeds 30 mol%, the efficiency of the oxidation-reduction reaction of iron or iron oxide decreases, which is not preferable. The method for preparing iron and the metal to be added is performed by a physical mixing method, an impregnation method, a coprecipitation method, or the like, and the coprecipitation method is particularly preferable.

  The cartridge 11 is made of a metal such as stainless steel or aluminum, a ceramic such as alumina or zirconia, or a heat-resistant plastic such as phenol resin or polyphenylene sulfide, and has a heat-resistant structure.

  The nitrogen gas generator 10 is provided with a cylindrical cover 17 having the same diameter as the main body 12 so as to cover the cartridge 11. As shown in FIG. 1B, the cover 17 is also detachably connected to the main body 12 at the end 13 on the side to which the cartridge is connected. Even if the cartridge 11 is covered with the cover 17, the pipe 14 b of the cartridge 11 is configured to protrude to the outside air from the opening on the opposite side of the cover 17. The cover 17 is made of, for example, a metal such as stainless steel or aluminum, or a plastic such as ABS resin or nylon, so that the user can be protected from heat when the cartridge 11 becomes hot. . A plurality of openings 18 are provided in the curved surface portion of the cover 17. By allowing outside air to freely flow through the opening 18 through the cover 17, the cartridge 11 is naturally cooled, and the internal temperature of the cartridge 11 can be adjusted.

  In order to suppress generation of hydrogen and carbon monoxide, which are impure gases, the internal temperature of the cartridge 11 is maintained at -20 ° C to 300 ° C. When the temperature exceeds 300 ° C., the oxygen absorbent cannot selectively react with oxygen in the air. On the other hand, when the temperature is lower than −20 ° C., the reaction rate becomes slow and the oxidation reaction does not proceed rapidly. A more preferable temperature is 0 ° C to 250 ° C, and a more preferable temperature is 50 ° C to 150 ° C.

  The temperature of the cartridge 11 can be adjusted using an electric heater or the like, but it is preferable not to use electricity from the viewpoint of increasing power consumption. Therefore, since the reaction between oxygen and the oxygen absorbent is an exothermic reaction, when it is necessary to store heat in order to maintain the temperature at −20 ° C. to 300 ° C., it is necessary to keep the cartridge 11 warm with a heat insulating material and cool it. In this case, it is preferable to cool the cartridge 11 with air.

  When the temperature is kept, a heat-resistant plastic such as polyphenylene sulfide or a heat insulating material such as glass fiber or ceramic fiber may be provided directly on the outer periphery of the cartridge 11, and the cover 17 does not have the opening 18, and the cover 17 It is also possible to provide a heat insulating material detachable from the cartridge 11 or the main body 12 such as air insulation or vacuum insulation.

  In the case of air cooling, in order to easily release heat from the cartridge 11, the surface area of the cartridge 11 can be increased by exposing the surface of the cartridge 11 to the outside air or providing a fin on the surface of the cartridge 11. As shown in FIG. 1A, a plurality of openings 20 are provided on both surfaces of the end portion 13 of the main body 12 on the cartridge 11 side and the opposite end portion, and a fan (not shown) is provided in the main body 12. The outside air can be actively blown from the fan in the main body 12 to the surface of the cartridge 11, or a liquid such as water can be circulated on the surface of the cartridge 11 for cooling. An appropriate structure for the heat insulation or air cooling is selected depending on the size of the nitrogen gas generator 10 and the cartridge 11 and the amount of nitrogen gas generated (oxidation rate).

  According to the above configuration, when the operation of the nitrogen gas generator 10 is started, first, the cartridge 11 is connected to the main body 12, the valve 15a is opened, and the knob 16 is turned to open the valve 15b. Then, the air pump in the main body 12 is activated, and air is introduced into the cartridge 11 from the outside air via the pipe 14a. When air is introduced into the cartridge 11, the air absorbent filled in the cartridge 11 quickly combines with oxygen in the air, oxygen is removed from the air, and a gas having a nitrogen concentration of 98% or more is obtained. Can do. The nitrogen rich gas is discharged from the pipe 14b and used as an inert gas.

When the oxygen absorbent in the nitrogen gas generator 10 deteriorates due to the oxidation reaction, the cartridge is replaced with a cartridge filled with a new oxygen absorbent. The cartridge filled with the deteriorated oxygen absorbent can be used again by introducing a reducing gas such as hydrogen in a reduction facility outside the system and reducing the deteriorated oxygen absorbent. If the gas used as the reducing agent is hydrogen, hydrogen filled in a high-pressure cylinder may be used. However, hydrocarbons such as liquid hydrogen cylinders and methane (hydrocarbon raw materials such as methane gas, natural gas or petroleum) are used as catalysts. Hydrogen produced by steam reforming using hydrogen, hydrogen produced by a steam reforming method using hydrocarbons and steam, hydrogen produced by methanol reforming, hydrogen produced by electrolysis of water, and the like can also be used. In any case, it is preferable to remove moisture and supply dry hydrogen before supplying the oxygen absorbent. An example of a reaction formula when the oxygen absorbent is iron and the reduction is performed with hydrogen is shown below.
Fe ₂ O ₃ + 3H ₂ → 2Fe + 3H ₂ O

  In order to monitor the deterioration degree of the oxygen absorbent, an oxygen sensor (not shown) for measuring the residual oxygen in the nitrogen gas may be provided at the gas outlet of the nitrogen gas generator, and whether or not oxygen remains. Oxygen detectors that can be identified by color changes may be provided, a temperature sensor (not shown) that measures the heat of oxidation generated during the oxidation reaction of the oxygen absorbent, or an increase in the weight of the oxygen absorbent due to oxidation. A pressure sensor (not shown) for measurement may be provided in the nitrogen gas generator.

  In addition, as air introduce | transduced into a nitrogen gas generator, the air dried with the air dryer, the silica gel, etc. can also be introduce | transduced. Thereby, a dry nitrogen-rich gas containing no vapor can be obtained. Alternatively, dry nitrogen-rich gas can be obtained by drying the nitrogen-rich gas discharged from the nitrogen gas generator with an air dryer or silica gel.

  Further, the cartridge will be described in more detail. 3 and 4 are schematic views showing a modified example of the appearance of the cartridge. The cartridge may be a rectangular parallelepiped 211 as shown in FIG. 3A or a cylindrical shape 212 as shown in FIG. In addition, the cartridge pipes 120 and 140 may be provided on the opposite surface as shown in FIG. 3C or on the side surface as shown in FIG. 3D without being provided on the same surface. Furthermore, in addition to providing one pipe for introduction and one for discharge, it is also possible to provide two pipes for introduction and two for discharge as shown in FIG.

  The number of cartridges stored in the nitrogen gas generator main body is not limited to one, and a plurality of cartridges can be stored. For example, as shown in FIG. 4A, two cartridges 213 may be connected in parallel by branching introduction pipe 120c and discharge pipe 140c. Thereby, air can be introduced into each of the plurality of cartridges 213 to generate nitrogen. Further, as shown in FIG. 4B, two cartridges 213 may be connected in series by a coupling plug 130. As a result, oxygen that has not been reacted with the oxygen absorbent in the first cartridge 213a can be purified to a higher concentration of nitrogen gas by reacting with the oxygen absorbent in the subsequent cartridge 213b. Thus, by connecting a plurality of cartridges in parallel or in series, the amount of nitrogen generated can be increased, or the amount of nitrogen generated per unit time, that is, the rate of nitrogen generation can be increased. The connection method of these cartridges can be selected according to the application of the nitrogen gas generator.

  5 to 7 are cross-sectional views schematically showing modified examples of the internal structure of the cartridge. As shown in FIG. 5A, an introduction pipe 120 and a discharge pipe 140 are provided on one surface of the cartridge 221. The inside of the cartridge 221 is partitioned by a separator 232 so as to have two layers of a layer in which the introduction pipe 120 is installed and a layer in which the discharge pipe 140 is installed. Each layer is filled with an oxygen absorbent. The separator 232 is provided with a gas passage hole 234 through which air can pass at a position away from the installation position of the pipe.

  According to such a configuration, the air introduced from the introduction pipe 120 reacts with the oxygen absorbent in the left layer of the separator 232 to become a nitrogen-rich gas. Then, the gas containing unreacted oxygen moves to the layer on the right side of the separator 232 through the passage hole 234 and further reacts with the oxygen absorbent. The purified nitrogen rich gas is discharged from the discharge pipe 140. Thus, by providing the separator 232 between the introduction pipe 120 and the discharge pipe 140 and providing the passage hole 234 at a position away from the plug of the separator 232, oxygen in the air introduced into the cartridge 221 is provided. Can be sufficiently reacted with the oxygen absorbent in the cartridge 221 and the reaction efficiency can be improved.

  Further, as shown in FIG. 5B, the introduction pipe 122 can be extended to the vicinity of the surface opposite to the face where the introduction pipe 122 is installed. Even with such a configuration, the oxygen in the air introduced through the introduction pipe 122 can sufficiently react with the oxygen absorbent in the cartridge 222. The same effect can be obtained by extending the discharge pipe 142 as shown in FIG. Further, in order to prevent the oxygen absorbent from scattering from the cartridge 224, as shown in FIG. 5 (d), although the gas passes near the inlets of the introduction pipe 120 and the discharge pipe 140, the oxygen absorption A filter 236 that does not allow the agent to pass therethrough may be provided.

  On the other hand, as shown in FIG. 6 (e), even if the introduction pipe 120 and the discharge pipe 140 are provided on opposite surfaces, the introduced oxygen in the air and the oxygen absorbent in the cartridge can react sufficiently. Can be made. Further, as shown in FIGS. 6 (f) and 6 (g), a plurality of separators 232 whose one ends are in contact with the inner wall of the container can be alternately provided. According to such a configuration, since the air flow path is further extended, the reaction efficiency can be further improved. Further, in order to prevent the oxygen absorbent from scattering from the cartridge 228, a filter 236 can be provided in the vicinity of the outlet of the discharge pipe 140 as shown in FIG. 6 (h). Since the cartridge 228 is pressurized in one direction, it is possible to substantially prevent scattering of the oxygen absorbent by providing the filter 236 only on the discharge pipe 140 side.

  Furthermore, as shown in FIG. 7 (i), a water vapor adsorbing portion 238 can be provided in the vicinity of the inlet of the introduction pipe 120 in the cartridge 229. The water vapor adsorption unit 238 is separated from the layer filled with the oxygen absorbent by the filter 236. The water vapor adsorbing portion 238 is filled with zeolite, silica gel, or the like in order to adsorb moisture in the introduced air. By providing such a water vapor adsorbing portion 238, almost the entire amount of moisture introduced into the cartridge 229 can be adsorbed immediately. Generation | occurrence | production of the hydrogen which is an impure gas can be suppressed because a water | moisture content does not contact an oxygen absorber.

  Although the nitrogen gas generator according to the present invention has been described using the embodiment shown in FIGS. 1 to 7, the present invention is not limited to this embodiment, and is within the scope of the technical idea of the present invention. All modifications and additions in are included in the present invention.

Example 1
Iron oxide to which Al was added was prepared by the coprecipitation method (urea method) shown below. First, iron (III) nitrate nonahydrate (Fe (NO ₃ ) ₃ · 9H ₂ O) is used so that Al ions become 3 mol% of all metal ions in 100 L of water deaerated with ultrasound for 5 minutes. 3.88 mol, aluminum nitrate (Al (NO ₃ ) ₃ .9H ₂ O) 0.12 mol, and 100 mol of urea as a precipitant were added and dissolved. The mixed solution was heated to 90 ° C. with stirring and maintained at the same temperature for 3 hours. After completion of the reaction, the mixture was allowed to stand for 48 hours, precipitated, and suction filtered. The obtained precipitate (BET specific surface area 52.1 m ² / g, average particle size 0.1 μm) was dried at 80 ° C. for 24 hours, and then air-baked at 300 ° C. for 3 hours and at 500 ° C. for 10 hours. . The Al-added iron oxide thus obtained was formed into pellets and then weighed 250 g (that is, if the product was composed entirely of Fe ₂ O ₃ and Al ₂ O ₃ , metal iron (Fe ) 170 g contained).

  Next, using this Al-added iron oxide, an experiment was conducted in which oxygen was removed from the air to produce high-concentration nitrogen. First, the Al-added iron oxide obtained as described above was stored in an atmospheric pressure fixed bed flow type container. This container was made of cylindrical stainless steel and was kept warm by covering with a heat insulating material made of silica fiber. And after raising a container to 500 degreeC with an electric furnace, hydrogen was introduce | transduced in the container and the reduction reaction was performed over 2 hours.

  Thereafter, the Al-added iron oxide reduced as described above was filled in an inert gas and connected to a nitrogen gas generator. The cartridge had a cylindrical shape with a flat brass surface, and it was not kept warm with a heat insulating material, but only a cover with a vent hole was attached. At normal temperature, 1.4 NL / min of air was sucked into the cartridge with an air pump, and the concentration of the discharged gas was measured. The results are shown in Table 1. In addition, as the air introduced into the apparatus, air having a temperature of 25 ° C. and a relative humidity of 40% passed through a silica gel drying tube to remove water vapor in the air to some extent was used. Further, the concentration of the discharged gas is indicated by a volume ratio from which water vapor is removed.

  As shown in Table 1, in the cartridge, oxygen was absorbed immediately at the moment when air was introduced, and a gas having a nitrogen concentration of 98% or more was stably generated at a flow rate of about 1 L / min for about 120 minutes. . The argon concentration in the gas was 1.2%, and the total of nitrogen and argon was 99% or more. Thereafter, with the passage of time, the oxidation efficiency of the oxygen absorbent decreased and the nitrogen concentration decreased. The total amount of nitrogen obtained in 120 minutes from the start of the reaction was 119NL. Moreover, hydrogen, carbon monoxide, and carbon dioxide were detected as components other than nitrogen, argon, and oxygen.

(Examples 2 to 19)
When preparing iron oxide, Ti, Zr, V, Nb, Cr, Mo, Ga, Mg, Sc, Ni, Cu, Nd, Rh, Ir, Ru, Pd, Pt, and Al—Pd were added instead of Al. Except for this, the experiment was performed in the same procedure as in Example 1. The gas concentration after 20 minutes from the intake of air into the cartridge was measured, and the results are shown in Table 2. As can be seen in Table 1, the highest concentrations of hydrogen, carbon monoxide, and carbon dioxide are observed as impure gases other than nitrogen, 20 minutes after the intake, so that the representative values of the evaluation results with additives are shown. Can be compared.

( Reference Example 20)
The experiment was performed in the same procedure as in Example 1 except that Al was not added during the preparation of iron oxide. The results are shown in Table 2.

As shown in Table 2, Examples 1 to 13 to which the second group of metals were added had lower concentrations of hydrogen and carbon monoxide than Reference Example 20 with only additive-free Fe. In Examples 14 to 18 to which the third group of metals was added, the concentrations of hydrogen and carbon monoxide were lower than those in Examples 1 to 13, and Examples 1 to 2 were added. 19 had the lowest hydrogen and carbon monoxide concentrations. From these results, it was found that the impurity concentration of hydrogen and carbon monoxide can be kept low with a predetermined additive, and a gas having high nitrogen purity can be stably generated.

In Examples 1, 17, 19 and Reference Example 20, the amount of nitrogen generated until the oxygen concentration reached 1% was also measured. The results are shown in Table 2. As shown in Table 2, in Example 1 to which Al was added, particle growth due to sintering was suppressed during the reduction reaction, and the oxidation reaction proceeded efficiently. As shown in Table 2, Example 17 to which Pd was added had high activity at the initial oxidation stage (around 20 minutes), but particle growth due to sintering was slightly observed during the reduction reaction. The activity was slightly inferior, and the amount of nitrogen generated was slightly reduced compared to when Al was added. In addition, in Example 19 in which both Al and Pd were added, particle growth during reduction was suppressed, and high activity was exhibited even in the oxidation reaction, and the amount of nitrogen generated was greatly increased. On the other hand, the additive-free Reference Example 20 absorbed oxygen, but resulted in inferior nitrogen generation as compared with the additive.

(Example 21)
The experiment was performed in the same procedure as in Example 1 except that the cartridge was blown and cooled with a fan. At this time, the maximum temperature in the cartridge and the amount of nitrogen generated until the oxygen concentration reached 1% were measured. These results are shown in Table 3.

(Example 22)
The experiment was performed in the same procedure as in Example 1 except that the cartridge was insulated with a ceramic boat having a thickness of 10 mm. Further, the maximum temperature in the cartridge and the amount of nitrogen generated until the oxygen concentration reached 1% were measured, and these results are shown in Table 3.

  As shown in Table 3, in the case of Example 21 that was blown and cooled by a fan, the maximum temperature inside the cartridge was 80 ° C., which was much lower than the temperature of 180 ° C. of Example 1 of natural cooling, and oxygen absorption The oxidation rate of the agent was slow, and the generation concentrations of hydrogen and carbon monoxide could be kept low. However, since the oxidation rate with oxygen was also inferior, the amount of nitrogen generated was reduced. In the case of Example 22 in which heat insulation was performed with a ceramic boat, the maximum temperature was 290 ° C., the reaction rate of the oxygen absorbent increased, and the nitrogen generation amount increased, but the generation amounts of hydrogen and carbon monoxide also increased. Increased.

It is a schematic diagram which shows the external appearance of one Embodiment of the nitrogen gas generator which concerns on this invention. It is a schematic diagram which shows the structure of one Embodiment of the nitrogen gas generator which concerns on this invention. It is a schematic diagram which shows the modification of the external appearance of the cartridge of a nitrogen gas generator. It is a schematic diagram which shows the modification of the external appearance of the cartridge of a nitrogen gas generator. It is sectional drawing which shows the modification of the structure of the cartridge of a nitrogen gas generator. It is sectional drawing which shows the modification of the structure of the cartridge of a nitrogen gas generator. It is sectional drawing which shows the modification of the structure of the cartridge of a nitrogen gas generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nitrogen gas generator 11 Cartridge 12 Main body 14 Piping 15 Valve 16 Knob 17 Cover 18, 20 Opening part 120 Introducing pipe 140 Exhaust pipe 211-229 Cartridge 232 Separator 234 Gas passage hole 236 Filter 238 Evaporating part

Claims (2)

A cartridge containing an oxygen absorbent that combines with oxygen in the air to remove oxygen from the air and generate a nitrogen-rich gas, and an introduction for introducing the air into the cartridge without heating from the atmosphere comprises a section, Ri detachably der the cartridge relative to the inlet portion, said oxygen absorber is an iron or iron oxide, which is a first metal, titanium, zirconium, vanadium, niobium, chromium, At least one metal selected from the second group consisting of molybdenum, aluminum, gallium, magnesium, scandium, nickel, copper and neodymium, or at least one selected from the third group consisting of rhodium, iridium, ruthenium, palladium and platinum. A nitrogen gas generator comprising two metals and prepared by a coprecipitation method . 2. The nitrogen gas generator according to claim 1 , wherein the oxygen absorbent includes both at least one metal selected from the second group and at least one metal selected from the third group.

Images