JP2004098037A - Oxygen absorber for increasing purity of nitrogen gas separated from compressed air - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of workability of packing, withdrawing, or the like caused by using iron powder, in a technique that the iron powder is used for furthermore increasing the purity of the nitrogen gas produced by a separation system. <P>SOLUTION: A particulate material obtained by solidifying the iron powder for absorbing the oxygen coexisting in the nitrogen gas by oxidation, activated carbon and sodium chloride is packed in deoxidization chambers 51, 52 being a deoxidizing means 50 through which the compressed nitrogen gas is made to pass for removing the oxygen coexisting in the nitrogen gas. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique relating to an oxygen absorption device for increasing the purity of nitrogen gas separated from compressed air, and more specifically, the purity of nitrogen gas separated from compressed air to produce high-purity nitrogen gas. The present invention relates to the technology of an oxygen absorbing device for enhancing the oxygen absorption.
[0002]
[Prior art]
Conventionally, as a technique for removing unnecessary gas and liquefying compressed air without liquefying the compressed air to produce nitrogen gas, two methods, a PAS method and a membrane separation method, have been generally used.
[0003]
Among them, the PAS method is an abbreviation of Pressure Swing Adsorption, which means that compressed air is passed through an adsorbent, which is a type of activated carbon, to adsorb a specific gas under high pressure, and to admit a specific gas under low pressure. This is a method in which nitrogen is separated by adsorbing oxygen or the like from compressed air by utilizing the characteristic of an adsorbent that discharges gas. In this case, the principle is the same as that of the peatless dryer, the apparatus is of a two-cylinder type, is larger than the membrane separation type, and requires a maintenance load such as a solenoid valve. Incidentally, the nitrogen purity was usually about 99 to 99.9999%.
[0004]
On the other hand, in the membrane separation method, compressed air is sent into a hollow fiber membrane, which is a hollow fiber-shaped polymer membrane, and nitrogen is separated using the difference in the amount of each gas component contained in the compressed air to the membrane. It is a method to do. In this case, although the size is smaller and the maintenance load is smaller than the PAS method, the nitrogen purity is about 95 to 99%, which is not suitable for the needs of high purity. However, depending on the flow rate of the compressed air to be sent, that is, the longer the time taken, the higher the nitrogen purity, and the higher the purity was 99.9%.
[0005]
However, in the membrane separation method, as a technique for further increasing the purity of the produced nitrogen gas, oxygen has been removed by oxidizing iron powder.
[0006]
[Problems to be solved by the invention]
However, with respect to such a conventional technology relating to a device for increasing the purity of nitrogen gas separated from compressed air, there are the following problems including an oxygen absorption device.
[0007]
First, in the case of the PAS method, the device becomes large, and there is a problem in maintenance of the device such as the solenoid valve.
[0008]
Next, in the case of the membrane separation method, the nitrogen purity is about 95 to 99.9%, which is not suitable for the needs of high purity.
[0009]
On the other hand, regarding technology that uses iron powder for the purpose of further increasing the purity of the nitrogen gas created by the membrane separation method, the use of powdered iron powder causes problems in workability such as filling and unloading. was there.
An object of the present invention is to solve such a problem.
[0010]
[Means for Solving the Problems]
In the present invention, in order to remove oxygen mixed in the nitrogen gas, the nitrogen gas in a pressurized state is passed through the deoxygenation chambers 51 and 52 of the deoxygenation means 50, and the nitrogen gas is oxidized into the nitrogen gas. When filling the mixed oxygen-absorbing iron powder, activated carbon, and sodium chloride, the iron powder, the activated carbon, and the sodium chloride are solidified and filled with particles, and furthermore, In solidifying the iron powder, the activated carbon, and the sodium chloride, a binder of a phenolic powder is used, and the iron powder, the activated carbon, the sodium chloride, and the binder are mixed. Further, the size of the particles is 1 to 8 mm, the binder is 2 to 6% by weight, and the activated carbon is 12 to 5% by weight, and the above-mentioned subject is further characterized by connecting water pots 51c, 52c for dropping water to the deoxygenating means 50 and opening / closing valves 51d, 52d. Settled.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
DETAILED DESCRIPTION OF THE INVENTION An oxygen absorber for increasing the purity of nitrogen gas separated from compressed air according to the present invention will be described in detail with reference to the drawings.
Here, FIG. 1 is a view showing the entirety of the present invention, and FIG. 2 is a detailed view of the deoxidizing means.
[0012]
As shown in FIG. 1, reference numeral 10 denotes an air compressor, which is not specifically shown, includes a motor, a compressor, and a tank, and transmits the rotation of the motor to the compressor by a belt to release the atmosphere. Compressed air is stored in the tank while taking in.
[0013]
As a whole configuration, the compressed air stored in the tank by the air compressor 10 includes a compressed air pipe 201, an on-off valve 11 that can be manually opened and closed, a compressed air pipe 202, 20 for drying by removing or absorbing air, compressed air piping 203, filter assembly 30 for removing various foreign substances from compressed air, compressed air piping 206, and hollow fiber membrane for removing oxygen from compressed air The aggregate 40, the nitrogen gas pipe 207, the deoxidizing means 50 for removing oxygen from the nitrogen gas, the nitrogen gas pipe 208, and the foreign matter taken into the nitrogen gas by passing the nitrogen gas through the deoxidizing means 50 A filter 60 for removal, a nitrogen gas pipe 209, a nitrogen gas tank 70 for storing nitrogen gas, a nitrogen gas pipe 210 Off valve 71 that can be opened and closed manually, by disposing the nitrogen gas pipe 211, and has a possible supply constituting the nitrogen gas.
[0014]
Here, the dryer 20 for drying the compressed air is generally of a type in which the moisture in the air is exposed by cooling the compressed air, thereby removing it as drain water. A method of absorbing water and a method of removing water by a separation membrane are also conceivable. In addition, as a cooling method, various methods such as a method using air and a method using water using various refrigerants can be considered. Naturally, the generated drain water can be discharged.
[0015]
The filter assembly 30 includes a pre-filter 31 for removing dust from compressed air, a compressed air pipe 204, a mist filter 32 for removing oil from compressed air, a compressed air pipe 205, and a micro mist filter for removing oil from compressed air. 33.
[0016]
As the filter assembly 30, three sets of filters, a pre-filter 31, a mist filter 32, and a micro-mist filter 33, are configured from the upstream. For example, the minimum size from the upstream is 3μ and 0.1μ. Or a foreign substance having a minimum size of 5μ, 0.5μ and 0.01μ, or another type. In general, a filter configuration that can capture a foreign substance having a minimum size of 1 to 5μ, 0.05 to 1μ and 0.01 to 0.05μ is considered. Can be It is also conceivable to arrange an activated carbon filter for removing odor as the filter at the most downstream.
[0017]
Further, as a structure of each of the filters 31, 32, and 33 constituting the filter assembly 30, for example, a configuration in which a filter element for capturing foreign matter is housed in all of the filter bodies can be considered. The filters 31, 32, and 33 are capable of discharging drain water that has accumulated due to dew condensation.
[0018]
In addition, the filters 31, 32, and 33 constituting the filter assembly 30 are not limited to the three sets of the filters 31, 32, and 33. As far as the arrangement is concerned, two sets of filters, four sets of filters, or a configuration of more sets of filters may be used.
[0019]
Next, regarding the hollow fiber membrane assembly 40, the hollow fiber membrane assembly piping 251 and the hollow fiber membrane 41, the hollow fiber membrane assembly piping 252, the throttle valve 41a, the hollow fiber membrane assembly piping 253 arranged in series, and The hollow fiber membrane assembly pipe 254, the hollow fiber membrane 42, the hollow fiber membrane assembly pipe 255, the throttle valve 42a and the hollow fiber membrane assembly pipe 256 arranged in series, and the hollow fiber membrane assembly pipe 257 arranged in series Three rows of the hollow fiber membrane 43, the hollow fiber membrane assembly pipe 258, the throttle valve 43a, and the hollow fiber membrane assembly pipe 259 are arranged in parallel. However, if the configuration is arranged in parallel, the number of rows is not limited to three, and one row or two rows may be used if the number is small, and four or more rows may be used if the number is large. .
[0020]
In this case, the hollow fiber membranes 41, 42, and 43 are made of a bundle of thousands of straw-shaped hollow fibers made of polyester, and each gas is passed through the hollow fibers by passing compressed air. Utilizing the inherent difference in the permeation speed of the hollow fiber membrane, the nitrogen gas contained most in the air remains.
[0021]
The speed at which the gas constituting the compressed air permeates through the hollow fiber membranes 41, 42, and 43 includes a gas that is released quickly and a gas that is not easily released, and the remaining gas is nitrogen gas. In particular, when the hollow fiber membranes 41, 42, and 43 are made of polyester, water vapor is most easily permeated, followed by hydrogen and helium, followed by carbon dioxide and carbon monoxide, and finally by oxygen, argon and nitrogen. In other words, nitrogen gas is the gas that is most difficult to permeate, and thus nitrogen gas remains.
[0022]
However, the hollow fiber membranes 41, 42, and 43 may be made of polyolefin or polypropylene resin in addition to polyester.
[0023]
Details of the deoxidizing means 50 for removing oxygen from nitrogen gas are as shown in FIG.
[0024]
Here, the deoxidizing means 50 shown in FIG. 2 includes a pipe 261 in the deoxidizing means arranged in series, an on-off valve 51a which is manually opened and closed, a pipe 262 in the deoxidizing means, a deoxygenating chamber 51, and a pipe in the deoxidizing means. Valve 263 that is manually opened and closed with the on-off valve 51b and the pipe 264 in the deoxidizing means, and a pipe 265 in the deoxidizing means arranged in series with the on-off valve 52a that is manually opened and closed, the pipe 266 in the deoxidizing means, and the deoxygenating chamber 52 Two sets of systems, that is, a pipe 267 in the oxygen means, an on-off valve 52b which is manually opened / closed, and a pipe 268 in the deoxidizing means are arranged in parallel.
[0025]
However, the configuration may not be such that two sets of systems are arranged in parallel, and may be a configuration of only one set of systems. In this case, the reason why the two sets of systems are configured in parallel is that the deoxidizing chambers 51 and 52 are made of iron powder mixed and granulated in order to remove oxygen contained in nitrogen gas by oxidation. It is filled with sodium chloride and activated carbon for accelerating the oxidation reaction of iron, but by constituting two sets of systems in parallel, the packing of either one of the deoxygenation chambers 51 and 52 can be filled. It is designed to prevent the entire system from completely shutting down by using the remaining set of systems during the procurement and replacement of the deteriorated packing when the system deteriorates. is there.
[0026]
Therefore, to describe the packing in detail, conventionally, powdered iron powder, sodium chloride and activated carbon for promoting the oxidation reaction of iron and the like are filled, but iron powder occupying most of the filling is used. Has a drawback that the workability in filling and taking out is very poor because of the powdery form.
[0027]
On the other hand, in the present invention, the above-mentioned disadvantages have been solved by using iron powder, sodium chloride or activated carbon, if necessary, adding a binder, mixing and solidifying to obtain granules. In this case, as the size of the granules, if it is too small, it is impossible to find a difference from the powder, and if it is too large, the reaction at the time of oxidation becomes worse. Was also effective from the viewpoint of reactivity. In particular, it was ideal to have a size of 2 to 4 mm.
[0028]
In addition, as a method for granulating, as a first method, iron powder or the like is directly pressed by a screw feeder and a roll press using a dry granulator without adding a binder as well as water to form a plate. In the second method, iron powder or the like containing a binder is pressed by a press pelletizer, and two to four conical rollers revolve and rotate on a die. While iron powder etc. containing the binder is entrapped and forced into the die, it is formed by cutting with a cutter and granulating, or as a third method, the binder is inserted by an extruder. It is conceivable to knead the iron powder or the like, form a plate material or a bar material, and granulate the material into a desired size.
[0029]
Furthermore, regarding the filler, in addition to the composition of iron powder, sodium chloride and activated carbon, in the case of iron powder only, in the case of iron powder only of activated carbon, in the case of iron powder only of sodium chloride, and in addition, a binder is added to each of them. Various changes can be considered, such as when added and when not added. In this case, with respect to the moisture retaining material, both the case where it is used and the case where it is not used can be considered according to the above-mentioned combination. In addition, it is possible to consider both the case where water is added and the case where water is not added, corresponding to all the combinations described above.
[0030]
In particular, with respect to sodium chloride, potassium chloride or calcium chloride may be used instead.
[0031]
By the way, as one example, it is ideal to use a mixture of 74% iron powder, 5% sodium chloride, 17% activated carbon, and 4% phenol resin powder as a binder by weight. I can do it.
[0032]
Regarding the amount of the binder to be added, if the amount of the binder is too large, the strength is increased, but the action of sodium chloride or activated carbon on the oxidation of iron powder is hindered. Is 3 to 5% by weight.
[0033]
Furthermore, when it comes to activated carbon, it is necessary to increase the amount of granulated particles as compared with conventional iron powder because oxygen is difficult to diffuse, and the amount is preferably 12 to 25% by weight, which is an ideal value. 15 to 20% by weight.
[0034]
On the other hand, when water is added by reacting these substances, heat is generated and moisture evaporates. Therefore, in order to supply the water evaporated by the heat generation, the water dehydration chambers 51 and 52 are provided with water pots 51c and 52c, which are manually opened and closed with the water supply pipes 291 and 293. 294 is connected by a valve.
[0035]
By the way, in the case of the deoxidizing means 50 shown in FIG. 2, water can be supplied from the water pots 51c and 52c to the deoxidizing chambers 51 and 52. It is also possible to provide a water tank individually or individually so that nitrogen gas can be surely passed through, so that moist nitrogen gas is fed into the deoxygenation chamber. Of course, the opening / closing valves 51d and 52d may have a function of opening at predetermined time intervals for a predetermined time instead of manually.
[0036]
Subsequently, the filter 60 removes oxygen when the nitrogen gas passes through the deoxidizing means 50. At the same time, the filter 60 becomes granular and is filled with iron powder, sodium chloride, activated carbon, or the like that should have been filled to remove oxygen. A part of the binder may be taken in as foreign matter by the nitrogen gas, and is provided for the purpose of removing them.
[0037]
Therefore, the filter 60 needs to have a performance capable of removing iron powder, sodium chloride, activated carbon, and a binder. By the way, from the filter 60, the drain water that has accumulated due to dew condensation can be discharged.
[0038]
Finally, the nitrogen gas tank 70 is for storing nitrogen gas. By providing the nitrogen gas tank 70, when supplying nitrogen gas from the nitrogen gas pipe 211, pulsation does not occur and the nitrogen gas tank 70 is continuously stabilized. It is possible to supply nitrogen gas in this state.
[0039]
The oxygen absorbing device for increasing the purity of the nitrogen gas separated from the compressed air according to the present invention is configured as described above, and its operation will be described in detail below.
[0040]
First, when the motor constituting the air compressor 10 is operated, the rotation of the motor is transmitted to the compressor by a belt, and the compressed air is stored in a tank.
[0041]
Here, the stored compressed air is supplied to the compressed air pipe 201, the on-off valve 11, the compressed air pipe 202, the dryer 20, the compressed air pipe 203, the pre-filter 31, the compressed air pipe 204, and the mist filter 32. The filter assembly 30 including the compressed air pipe 205 and the micro mist filter 33 is sent to the hollow fiber membrane assembly 40 via the compressed air pipe 206.
[0042]
In this case, in the dryer 20, the compressed air is dried by removing or absorbing moisture, and in the filter assembly 30, the filters 31, 32, 33 and possibly other filters such as an activated carbon filter are constituted. This removes various foreign substances such as oil and dust.
[0043]
In the hollow fiber membrane assembly 40, the throttle valves 41a, 42a, and 43a connected to the hollow fiber membranes 41, 42, and 43 are individually adjusted, so that the downstream of each of the throttle valves 41a, 42a, and 43a is adjusted. In the hollow fiber membrane assembly pipes 253, 256, and 259, all pipes can ensure the same purity of nitrogen gas. Specifically, by individually adjusting the throttle valves 41a, 42a, and 43a by each of the hollow fiber membranes 41, 42, and 43, 99. Nitrogen gas having a purity of about 5% can be secured.
[0044]
Next, the nitrogen gas having a certain degree of purity secured in the hollow fiber membrane assembly 40 is sent to the deoxidizing means 50 via the nitrogen gas pipe 207.
[0045]
In this case, the nitrogen gas having a purity of about 99.5% is charged into the deoxidizing chambers 51 and 52 constituting the deoxidizing means 50 by the deoxidizing means 50 via the nitrogen gas pipe 207. Of the granular iron powder, sodium chloride, activated carbon and the binder, the iron powder is oxidized to remove oxygen from the nitrogen gas and further increase the purity of the nitrogen gas.
[0046]
At that time, 99.9% nitrogen gas purity was made possible by using sodium chloride, activated carbon and a small amount of water, and sometimes using a water absorbing material to promote the oxidation reaction of iron as a reactant. It is.
[0047]
In addition, as a reactant, it is not added at all, only water or water and a water retention agent is added, only sodium chloride is added, or only sodium chloride and water or water and a water retention agent are added, Various changes can be considered, such as adding only activated carbon, adding only activated carbon and water or only water and a water retaining agent, or adding only sodium chloride, activated carbon and water, or adding only water and a water retaining agent.
[0048]
Here, the reason that the two sets of systems are configured in parallel in the deoxidizing means 50 is that one of the two systems constituting the deoxidizing means 50 is filled in the deoxidizing chambers 51 and 52. When the iron powder or the like of one system deteriorates, it is disposed for the purpose of using iron or the like of the other system. Therefore, when one system is used, the nitrogen gas does not flow through the system by closing one of the open / close valves 51a, 51b or the open / close valves 52a, 52b disposed in the other system. That's how it works.
[0049]
Regarding the on-off valves 51d and 52d connected to the water pots 51c and 52c, depending on the situation of heat generation in the deoxygenation chambers 51 and 52 and the downstream thereof and the necessity of moisture due to a change in the concentration of oxygen gas or the like. It can be opened and closed.
[0050]
Finally, the nitrogen gas whose purity has been increased by the deoxygenating means 50 is sent to the filter 60 via the nitrogen gas pipe 208, and the nitrogen gas in the filter 60 becomes granular when passing through the deoxygenating means 50. The purpose is to remove foreign substances taken in by nitrogen gas in iron powder, sodium chloride, activated carbon, and part of the binder which are filled to remove oxygen, and further through a nitrogen gas pipe 209. And stored in a nitrogen gas tank 70. Here, the nitrogen gas stored in the nitrogen gas tank 70 is supplied from the nitrogen gas pipe 211 by opening the on-off valve 71 as needed.
[0051]
【The invention's effect】
As is apparent from the above description, the following effects can be obtained by the present invention.
[0052]
First, by making the iron powder, sodium chloride, and activated carbon charged in the deoxidizing chamber that constitutes the deoxidizing means into granules, it is easier to manage and the workability for filling is remarkably improved. Improved.
[0053]
Secondly, when the iron powder, sodium chloride or activated carbon filled in the deoxidizing chamber is granulated, it can be easily granulated by using a binder.
[0054]
Third, by setting the size of the particles to 1 to 8 mm, the workability was improved while the reactivity was maintained at a certain level.
[0055]
Fourth, by making the proportion of the binder 2 to 6% by weight, it has become possible to promote oxidation while securing strength.
[0056]
Fifth, by making the ratio of activated carbon 12 to 25%, oxygen can be easily diffused.
[Brief description of the drawings]
FIG. 1 is a view showing the entirety of the present invention. FIG. 2 is a detailed view of a deoxidizing means.
10 Air compressor 11 Open / close valve 20 Dryer 30 Filter assembly 31 Pre-filter (filter)
32 ... Mist filter (filter)
33 ・ ・ ・ ・ ・ ・ ・ Micro mist filter (filter)
40 hollow fiber membrane assembly 41 hollow fiber membrane 41a throttle valve 42 hollow fiber membrane 42a throttle valve 43 hollow Thread film 43a ... Throttle valve 50 ... Deoxygenation means 51 ... Deoxygenation chamber 51a ... On / off valve 51b ... On / off valve 51c ... Water pot 51d ... ... On-off valve 52 ... Deoxygenation chamber 52a ... On-off valve 52b ... On-off valve 52c ... Water pot 52d ... On-off valve 60 ... Filter 70 ... Nitrogen gas tank 71. ..Compressed air piping 206 ... Compressed air piping 207 ... Nitrogen gas piping 208 ... Nitrogen gas piping 09 Nitrogen gas pipe 210 Nitrogen gas pipe 211 Nitrogen gas pipe 251 Hollow fiber membrane aggregate pipe 252 Hollow fiber membrane aggregate pipe 253 · Hollow fiber membrane assembly piping 254 ··· Hollow fiber membrane assembly piping 255 ··· Hollow fiber membrane assembly piping 256 ··· Hollow fiber membrane assembly piping 257 ··· Hollow fiber membrane assembly Pipe 258: hollow fiber membrane assembly pipe 259: hollow fiber membrane assembly pipe 261: pipe in deoxygenation means 262: pipe in deoxygenation means 263: deoxygenation Means piping 264 ... Deoxygenating means piping 265 ... Deoxygenating means piping 266 ... Deoxygenating means piping 267 ... Deoxygenating means piping 268 ... Deoxygenation Means pipe 291 Water supply pipe 292 Water supply pipe 293 Water supply pipe 294 ... water supply pipe

Claims (6)

In order to remove oxygen mixed in the nitrogen gas, the nitrogen gas in the deoxygenation chamber (51, 52) through which the nitrogen gas under pressure passes passes through the nitrogen gas by oxidation. When filling the mixed iron powder, activated carbon and sodium chloride which absorbs the oxygen, compression is characterized in that the iron powder, the activated carbon and the sodium chloride are solidified into particles and filled. Oxygen absorber to increase the purity of nitrogen gas separated from air. When solidifying the iron powder, the activated carbon, and the sodium chloride, a binder of a phenolic powder is used, and the iron powder, the activated carbon, the sodium chloride, and the binder are mixed. Item 2. An oxygen absorber for increasing the purity of nitrogen gas separated from compressed air according to item 1. 3. The oxygen absorber according to claim 2, wherein the size of the particles is 1 to 8 mm. The oxygen absorber according to any one of claims 1 to 3, wherein the binder is 2 to 6% by weight. The oxygen absorber according to any one of claims 1 to 4, wherein the activated carbon is contained in an amount of 12 to 25% by weight. 6. A water pot (51c, 52c) for dropping water to said deoxygenating means (50) and an on-off valve (51d, 52d) are connected to each other. An oxygen absorber for increasing the purity of nitrogen gas separated from the compressed air as described.

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