JPH03218910A - Method and device for recovering argon - Google Patents

Abstract

PURPOSE:To reduce the recovery cost by mixing a waste gas having low contents of H2 and/or CO as compared with O2 content and a waste gas having high contents of the above gases, converting the O2 in the mixture into H2O and/or CO2 and then refining the mixture by adsorption. CONSTITUTION:The waste gas having higher contents of H2 and/or CO than the theoretical value as compared with the O2 content is collected in a first holder 21 through a switching valve 30, then compressed and stored in a second holder 23. The waste gas having low contents of H2 and/or CO as compared with the O2 content is collected in a gas holder 2 through the switching valve 30 and supplied to Pt or Pd-based catalyst reaction equipment 5. The O2 and CO contents of the waste gas are measured by a flowmeter 11, an O2 analyzer 12 and a CO analyzer 13 to calculate the deficiency of CO, and a specified amt. of the waste gas in the second holder 23 is supplied to the equipment 5 through a flow controller 24. The O2 in the waste gas is completely converted into H2O and CO2 which are removed by the succeeding refining equipment 6 by adsorption, and gaseous Ar is separated and recovered.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and apparatus for recovering argon, and in particular to recovering argon from argon-containing exhaust gases of various compositions discharged from various refining processes such as steel plants. The present invention relates to a method and apparatus for doing so.

[Conventional technology]

Traditionally, large amounts of argon have been used in the refining process of steel plants, such as in continuous casting furnaces, vacuum degassing furnaces, bottom bubble links in converters, and argon-oxygen blowing furnaces.
As a method for recovering argon in exhaust gas, for example, Japanese Patent Laid-Open Nos. 59-152210 and 60-
A number of proposals have been made, as shown in 204608, 60-239309, and 63189774.

FIG. 2 is a system diagram showing an example of a conventional argon recovery method.

First, the exhaust gas discharged from various furnaces 1 is transferred to the gas holder 2.
After being stored in the exhaust gas, it is sent to a first pressure fluctuation adsorption separation device (hereinafter referred to as IPSA) 4 by a compressor 3, where nitrogen, carbon monoxide, and carbon dioxide in the exhaust gas are removed. No. IP
In the exhaust gas leaving SA4, the amount of oxygen or hydrogen remaining in the exhaust gas without being removed by IPSA4 is quantified by a continuous analyzer (not shown), and the amount of hydrogen or oxygen is determined according to the analysis value. After being added, it is sent to catalytic reaction facility #i5 where oxygen and hydrogen undergo a combustion reaction and are converted into water.

The exhaust gas in which oxygen and hydrogen have been converted to water is sent to a second pressure fluctuation adsorption separation device (hereinafter referred to as purification equipment) 6 to remove moisture and recover argon.

In addition, 7 and 7 in the figure are vacuum pumps for discharging components other than argon.

[Problem to be solved by the invention]

However, the exhaust gases emitted from the various furnaces mentioned above contain carbon monoxide and carbon dioxide generated from smelting. Because large amounts of hydrogen, nitrogen, and air components (nitrogen, oxygen) are mixed in during gas cooling, the process to remove these gas components other than argon is complicated, and the cost of recovery equipment is high, making it difficult to put into practical use. I was late.

Furthermore, even in the methods that have been tried and put into practical use, it was necessary to add more than the stoichiometric amount of oxygen or hydrogen in order to remove hydrogen or oxygen from the exhaust gas. In particular, in order to remove oxygen, which is difficult to separate from argon by adsorption, to the order of 1) pl, it is necessary to add an excessive amount of expensive hydrogen.

Therefore, an object of the present invention is to provide an argon recovery method that can recover argon at low cost without using expensive hydrogen.

[Means to solve the problem]

In order to achieve the above object, the argon recovery method of the present invention recovers argon from the argon-containing exhaust gas discharged from the refining process of a steelworks, etc., when the amount of hydrogen and/or Or, by mixing exhaust gas with a low total carbon monoxide content and exhaust gas with a high total hydrogen and/or carbon monoxide content compared to the oxygen content, the oxygen in both exhaust gases is replaced with hydrogen and/or carbon monoxide. It is characterized by performing adsorption purification after reacting with carbon oxide to convert it into water and/or carbon dioxide, and furthermore, the total content of hydrogen and/or carbon monoxide is smaller than the amount of oxygen contained. The large amount of exhaust gas must be collected and stored during the refining process, which has a high concentration of hydrogen and/or carbon monoxide, and the amount of mixture of both exhaust gases is equal to the amount of hydrogen and/or monoxide after mixing both exhaust gases. It is characterized in that the total carbon content is controlled so as to contain more than the stoichiometric amount of hydrogen and/or carbon monoxide that removes oxygen from both exhaust gases.

Further, the argon recovery device of the present invention is a main recovery system in an argon recovery device that recovers argon in exhaust gas containing argon discharged from a refining process etc. using a catalytic reaction equipment and a pressure fluctuation adsorption separation device. In addition, an addition system is provided that branches off with a switching valve, and the main recovery system is provided with an oxygen analyzer, a carbon monoxide analyzer, and a flow meter, and the addition system is provided with signals from the holder and both analyzers. The present invention is characterized in that a flow rate adjustment device operated by the above is provided, and a path is provided for introducing the exhaust gases of both systems into the catalytic reaction equipment.

[For production]

Therefore, most of the oxygen contained in the exhaust gas can be reacted with hydrogen and/or carbon monoxide and converted into water and/or carbon dioxide, which can be easily adsorbed and removed, making it unnecessary to add expensive hydrogen. be able to.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on an embodiment shown in FIG. In the following description, the same elements as those in the conventional example shown in FIG.

FIG. 1 is a system diagram showing an argon recovery apparatus to which the present invention is applied, in which exhaust gas discharged from a furnace 1 is passed through a catalytic reaction equipment 5, a purification equipment! The systems to be introduced into 6 are a main recovery system 10 equipped with a gas holder 2 and a compressor 3 as in the past, and a first recovery system 10.
Holder 21, compressor 22. It is composed of a second holder 23 and a carbon monoxide addition system 20 connected to the main recovery system 10 via a flow rate adjustment device 24.

That is, a switching valve 30 is provided in the pipe line for recovering the argon-containing gas discharged from the furnace 1, so that the exhaust gas (with a total content of hydrogen and/or carbon monoxide smaller than the amount of oxygen contained) is installed.
Separates exhaust gas whose total amount of hydrogen and carbon monoxide is less than the stoichiometric amount for removing oxygen from exhaust gas) and exhaust gas whose total amount of hydrogen and/or carbon monoxide is higher than the amount of oxygen it contains. It is formed so that both exhaust gases can be mixed at a predetermined ratio.

Here, an example of the exhaust gas composition [volume %] generated by each process in the vacuum degassing furnace is shown in Table 1.

As is clear from Table 1, the exhaust gases emitted by treatments B and D contain sufficient amounts of hydrogen and carbon monoxide to convert oxygen into water or carbon dioxide, that is, hydrogen and carbon monoxide per 1 mole of oxygen. The total amount of hydrogen and carbon monoxide is 2 moles or more.

Therefore, the exhaust gas generated by processing B and processing D passes through the main recovery system 10, that is, from the switching valve 30 and is recovered into the gas holder 2, and is then controlled by the compressor 3 to a predetermined pressure, e.g.
It is compressed to 8.0 kg/c/g and introduced into the catalytic reaction equipment 5 with the same composition.

On the other hand, the amount of hydrogen and carbon monoxide in the exhaust gas in treatment C is not sufficient to convert all of the oxygen in the exhaust gas, and the amount of hydrogen and carbon monoxide in the exhaust gas in treatment C is not sufficient to convert all of the oxygen in the exhaust gas. Contains a relatively large amount of carbon monoxide.

Therefore, the exhaust gas generated by the process A is collected in the first holder 21 via the switching valve 30, and is further processed by the compressor 22 at a pressure slightly higher than that of the main recovery system 10, e.g. The pressure is increased to 8.0 kg/cJ G and stored in the second holder 23.

If excess oxygen is generated in the process C, the exhaust gas is recovered from the switching valve 30 into the gas holder 2, and introduced into the catalytic reaction equipment 5 via the main recovery system 10 via the compressor 3. A flow meter (Fl) 11, an oxygen analyzer (AO2) 12, and a carbon monoxide analyzer (ACO) 13 provided in the main recovery system 10 continuously measure the amount of oxygen and carbon monoxide in the exhaust gas. The amount of carbon monoxide lacking is calculated by measuring the amount of carbon monoxide, and the second holder 23 of the addition system 20
The exhaust gas of process A stored in the flow rate support regulator (F
A predetermined amount is introduced via a flow rate control device 24 consisting of a flow rate control valve (FCV-1) and a flow rate control valve (FCV-1). The amount introduced should be adjusted so that the total amount of hydrogen and carbon monoxide relative to oxygen is more than stoichiometric in order to convert oxygen sufficiently.

In this way, exhaust gas has a lower total content of hydrogen and/or carbon monoxide than the amount of oxygen it contains, and exhaust gas has a higher total content of hydrogen and/or carbon monoxide than the amount of oxygen it contains. By mixing at a predetermined ratio, the amount of hydrogen and carbon monoxide can be reduced so that the oxygen contained in both exhaust gases can be completely converted into water and carbon dioxide that can be easily adsorbed and removed in the next step, catalytic reaction equipment 5. can.

Catalytic reaction facility #I5 causes a combustion reaction (catalytic deoxidation reaction) between oxygen and hydrogen or carbon monoxide in the exhaust gas using a platinum-based or palladium-based catalyst, and converts them into water or carbon dioxide. The exhaust gas deoxidized in this way is sent to the purification equipment 6, where moisture, nitrogen and other substances are removed from the gas. Carbon monoxide, carbon dioxide, and trace amounts of hydrogen are adsorbed and removed for purification. This purification equipment 6 can use a conventionally used pressure fluctuation adsorption separation device, and can be of an appropriate type such as a two-column type or a three-column type depending on the purity of the argon to be recovered. Argon can be separated and recovered by substantially the same operation.

Therefore, oxygen in the exhaust gas can be removed by simply adding equipment without using expensive hydrogen, and running costs can be significantly reduced.

Furthermore, when the argon content is extremely low compared to the exhaust gas from other treatments, such as the exhaust gas emitted by treatment A, conventionally the exhaust gas was subjected to appropriate abatement treatment before being discharged. According to the method, argon in such a low-argon exhaust gas can also be recovered, and the argon yield can be increased.

The method of the present invention is not limited to the configuration shown in the above-mentioned embodiments, and can be implemented with a recovery device having an appropriate configuration. For example, the first holder 21 of the addition system 20 may be omitted and the switching valve 3
The exhaust gas may be pressurized by directly connecting the compressor 22 to the exhaust gas, and when the oxygen concentration in the exhaust gas is approximately constant, the measurement of the oxygen concentration can be omitted. Furthermore, the exhaust gas is not limited to exhaust gas discharged from the same furnace, and exhaust gas discharged from various other furnaces, for example, exhaust gas with a high hydrogen content, may be mixed.

In such a case, in addition to the above-mentioned two analyzers, a hydrogen analyzer may be provided in the main recovery system and connected to the flow rate regulator of the addition system so that the hydrogen content can also be controlled. .

〔Effect of the invention〕

As explained above, the argon recovery method of the present invention
Oxygen is produced by mixing exhaust gas with a lower total hydrogen and/or carbon monoxide content than the oxygen content and exhaust gas with a higher total hydrogen and/or carbon monoxide content than the oxygen content. Since this method removes oxygen, oxygen can be removed without preparing expensive hydrogen, and the running cost of argon recovery can be reduced.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing one embodiment of the argon recovery device of the present invention, and FIG. 2 is a system diagram of a conventional argon recovery device. 1...Furnace 2...Gas holder 3...Compressor 5...Catalytic reaction equipment 6...Refining equipment 10
...Main recovery system 20...Addition system 24...
・Flow rate adjustment device 30...Switching valve younger 2 circles

Claims (1)

[Claims] 1. When recovering argon from exhaust gas containing argon discharged from the refining process of a steelworks, the total content of hydrogen and/or carbon monoxide is smaller than the amount of oxygen contained. Exhaust gas is mixed with exhaust gas that has a higher total content of hydrogen and/or carbon monoxide than the amount of oxygen it contains, and the oxygen in both exhaust gases is reacted with hydrogen and/or carbon monoxide to form water and/or A method for recovering argon, which comprises converting it into carbon dioxide and then performing adsorption purification. 2. It is confirmed that the exhaust gas with a total content of hydrogen and/or carbon monoxide that is higher than the amount of oxygen contained is collected and stored during the refining process where the concentration of hydrogen and/or carbon monoxide is high. The method for recovering argon according to claim 1. 3. The mixing amount of both exhaust gases is such that the total content of hydrogen and/or carbon monoxide after mixing both exhaust gases is equal to or higher than the stoichiometric amount to remove oxygen from both exhaust gases. The method for recovering argon according to claim 1 or 2, wherein the argon is controlled to contain. 4. In an argon recovery system that recovers argon in the exhaust gas containing argon discharged from the refining process, etc. using catalytic reaction equipment and pressure fluctuation adsorption separation equipment, in addition to the main recovery system, there is a branch with a switching valve. a main recovery system is provided with an oxygen analyzer, a carbon monoxide analyzer, and a flow meter, and the addition system is provided with a flow rate adjustment device that is operated by signals from the holder and both analyzers, An argon recovery device characterized in that a path is provided for introducing the exhaust gases from both of the systems to the catalytic reaction equipment.