JPS63189774A - Method of recovering ar gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to equipment using Ar, such as Ar-0s blowing furnace and R
The present invention relates to a method for recovering Ar gas from Ar-containing exhaust gas in H-liquid vacuum degassing equipment and the like.

[Prior art and its problems]

Recently, Ar gas has been widely used in the refining process of steel manufacturing. For example, (1) Ar-0,
The blowing method makes it possible to decarburize expensive Cr without oxidizing it by injecting Ar into the molten steel together with 03.It also provides good quality, so it is being used as a new method for producing high Crg4 molten steel. It has attracted attention and is being used in smelting.

(2) The molten steel degassing method, which is also carried out for the purpose of degassing during the refining process during the steelmaking process, is a process that reduces harmful 11°N and O gases as impurities in 18aq by exposing molten steel to a vacuum. At that time, an inert gas is passed through the molten steel as a reflux gas and a tuyere cooling gas.
A'' is used as an inert gas when melting 01L.

In addition, not only for the above-mentioned Cr-containing steel but also for ordinary refining, a method of 08 refining while stirring molten steel with Ar has been adopted for the purpose of improving decarburization efficiency. or,
Its usage is also rapidly increasing.

Industrially, this Ar gas is manufactured by further concentrating and refining Ar-containing gas obtained from an air cryogenic FLI device using an Ar concentrator. Since this only includes a certain amount, it is expected that there will be a shortage of supply to meet the above demand in the future. It is also very expensive.

Therefore, in order to reduce the amount of Ar used, various attempts have been made to separate and recover Ar from the waste gas containing spent A.
O! In a method for recovering Ar gas from blowing furnace exhaust gas,
The exhaust gas generated from the furnace mouth is isolated from the atmosphere and collected, and the CO in the exhaust gas is absorbed and removed with a Cu-N1t complex.
This method involves absorbing and removing COl in an amount of Il using an alkali, and recovering and reusing Ar gas. Also, JP-A-54-1493
No. 90 is a method in which the exhaust gas generated from the furnace mouth is subjected to a pretreatment process in which CO is converted to CO8 by combustion using O3, and then adsorbed and separated using a vacuum adsorption method or the like.

The conventional examples have been described above, but
No. 90 requires absorption and dissipation operations, which poses problems for utilities, and the H mixed in the exhaust gas.
It is difficult to completely remove z, 0-, N* gas, etc., and there are drawbacks such as a decrease in Ar recovery rate. In addition, in JP-A-54-1403Of3, the CO in the exhaust gas is combusted with O gas at the furnace opening, which results in a huge
There are drawbacks such as the need for an expensive dust collector to cool and collect the exhaust gas, and the waste of a large amount of expensive pure oxygen gas in the combustion of CO gas.

The present invention has been made in order to eliminate the above-mentioned drawbacks. The purpose of the present invention is to provide a method for separating and recovering highly concentrated A'' that is not necessary, is low cost, and has high recovery efficiency.

[Means for solving problems]

The Ar recovery method according to the present invention is a method for recovering Δ'' from Ar-containing exhaust gas discharged from equipment using Ar, in which the exhaust gas is adsorbed by a pressure fluctuation adsorption method to form an Ar-enriched gas. After that, the Ar iQ condensed gas is introduced into the pure Ar purification process in the air cryogenic separation method to produce Ar
The feature is that the gas is recovered.

Hereinafter, the method of the present invention will be specifically explained based on the drawings.

FIG. 1 is a system diagram showing one implementation of the method of the present invention. In the figure, 0) is Ar-using equipment such as an Ar-0-blown N furnace or RII vacuum degassing equipment, and the Ar-containing exhaust gas generated from the equipment (1) is forced to burn through 01 gas enrichment, etc. The gas is sucked in by the induced blower (2) without being forced to move, is sent to the dust remover (3) to remove dust, and is then stored in the exhaust gas holder (4). After that, the exhaust gas is pressurized to about 5 to 10 atmospheres by a compressor (ω), and absorbed by pressure fluctuation adsorption method (hereinafter referred to as PSA method).
(6).

P S A Law J, Le Ha (6) Lt.
, Co, Cot, and N, and a vacuum pump (8
) and a series of automatic switching valves (9). In each suction tower (7a) to (7C), a suction processing cycle consisting of, for example, pressure equalization, pressurization, adsorption, desorption, and purge is repeated by the operation of the automatic switching valve (9) group.
co, co, and N.

is adsorbed and removed and 'I5-condensed Ar gas is taken out.

Here, it is better to adsorb and remove CO, CO, and N in the exhaust gas as much as possible to obtain a highly purified Δr concentrated gas, but as for Nt, the greater the degree of removal, the following formula There is a drawback that the Ar yield represented by is reduced. FIG. 2 is a graph showing the relationship between the N8 concentration (%) in the Ar concentrated gas and the Ar yield (%) after it has been adsorbed by the adsorption device (6) to form an Ar10 condensed gas. be. A
The r yield (%) increases as more N is adsorbed and removed, that is, Ar
ρN in the condensed gas, the smaller the 6 degrees, the higher the Ar yield (%
) becomes low (it turns out that it becomes evil).

Therefore, in the present invention, the adsorption treatment is performed so that as much N as possible remains, and this residual N is introduced into the pure Ar purification step in the air cryogenic separation method to be described later. This improves the yield rate.

The Ar gas thus concentrated is once stored in the Ar gas holder 〇〇, and then compressed by the compressor q
It is compressed to about 2 kIc/cJ and introduced into the pure Ar purification step (22) in the air one-mold cooling separation method described later.

Next, 1 ton of air by air z7 cold separation method! i'A
I will explain the location.

q[ indicates an air component Ii[l apparatus by the air cryogenic separation method, and the production of pure Ar in this air cryogenic separation method consists of the process parts (A) to (+) shown below.

(A) Inhale air and use bag filter-03,
Remove dust etc. from the air.

(B) The raw air is compressed to 5k by the raw air compressor α4.
g/cJ. Further, if necessary, the raw air is washed and cooled in a water washing tower (not shown).

(C) Heat exchanger 09 exchanges raw air with impure Nl and pure N
By exchanging heat with , , O, and lowering the temperature of the raw material air, CO1 and the like are separated as solids.

(D) Part of the compressed raw air is expanded into an expansion turbine aQ.
It expands and becomes a cold source.

(E) Feed air is introduced from the lower part of the air separation tower G force, and by utilizing the difference in boiling point (liquefaction point), Ot in the air is
, Nt, and Ar. On the other hand, hydrocarbons contained in the feed air are removed by a hydrocarbon adsorber (not shown), and C, H, contained in the liquid 08 are removed.

It is adsorbed by an adsorber (not shown).

(F) Product N is extracted from the upper part of the upper column of air separation column Q7), and product O8 is extracted from the lower part of the upper column. In addition, from the middle of the upper column, a gas with an Ar purity of about 12% and almost no Nu content is extracted as a feed gas (.

(G) The feed gas is separated in a crude Ar column (le) using the same principle as the air separation column aD, and about 96% of the crude A is separated.

(H) Ol in crude Ar is purified by room temperature Ar purifier a (1!
In IB, it is reacted with N2 to form water, and dehumidified in a dehumidifier (to) to remove 01 minutes.

(Summer) In the high-purity Ar tower (21), N□ and excess H were added.
z8'' is separated to collect purified Ar.

As described above, high purity A is obtained from air through the steps (^) to (+>).
r can be extracted continuously.

By the way, the Ar6 condensed gas obtained by adsorbing Ar-containing exhaust gas by the above-mentioned PSA method contains unseparated N.
2. -01 and N remaining at about 1 to 2% coexist. The present invention produces high-purity 11fAr by removing the unseparated Hz, Om, and residual N in the pure Ar purification step (22) in the air cryogenic separation method (11) and (+). The purpose is to collect In Domu Ar purifier 03, as shown in the step (l()), Hz
The water is added to water, reacts with 0 in the gas to be processed, becomes water, and is adsorbed and removed in a subsequent dehumidifier. Therefore, the process of burning and removing N2 and Ol, which is performed as a pretreatment for the adsorption device (6) using the PSA method, becomes unnecessary, and the equipment is simplified. Next, in the high-purity Ar column (21), N is separated and removed as shown in step (1) above to obtain high-purity Ar. Here, in order to efficiently collect high-purity Ar, N8 in the Ar concentrated gas fed to the high-purity Ar column (21) is usually allowed to be mixed in an amount of up to 2%, so the above-mentioned PSA In the adsorption process using the method, the flow rate of the Ar condensed gas is adjusted to wJ using the control valve (23) so that N1 is at most 2%, and then the pure Ar purification process is performed with 4%.
people Thereby, the Ar recovery rate in the adsorption treatment step can be increased, and highly pure Ar can be efficiently collected.

[Embodiments of the invention]

Example 1 Degassing was performed using the RH vacuum degassing equipment under the operating conditions shown in Table 1, and the exhausted Ar-containing exhaust gas shown in Table 2 was stored in an exhaust gas holder, and then transferred to an adsorption device using the PSA method. As a result of Ar recovery, ArQ condensed gas having the composition shown in Table 3 was obtained with a yield of 75%.

(Left below) Table 1 Table 2 Table 3 Next, this Are condensed gas 100 Nr+? /H, crude Ar
As a result of mixing with 500 Nr+t'/H of crude Ar gas obtained from the column and subjecting it to a pure Ar purification process, the purity was 99.999%.
High purity Ar was stably obtained.

Example 2 Ar-0, fl' was produced in a blowing furnace under the operating conditions shown in Table 4.
The Ar-containing exhaust gas shown in Table 5 that was exhausted at that time was stored in an exhaust gas holder, and then Ar was recovered using an adsorption device using the PSA method.
5 condensed gases were obtained with a yield of 75%.

Table 4 m5 Table 6 Table 6 As a result of mixing 100 N♂/H of Ar concentrated gas with the crude Ar gas 500 NJ/H obtained from the crude Ar column and subjecting it to a pure Ar purification process, the result was 99°989 % high purity A
``was obtained stably.

〔Effect of the invention〕

As explained above, according to the method of the present invention, there is no need for a pretreatment step such as forced combustion to remove Co, H, etc. from the Ar-containing exhaust gas, and N, which is difficult to separate, from the exhaust gas is removed. By separating and removing the gas in two steps: the adsorption treatment process using the PSA method and the pure Ar purification process using the air-a cold separation method, it is possible to separate high-purity Ar gas with high recovery efficiency and at low cost. It can be recovered.

[Brief explanation of the drawing]

21￥1 Figure is a schematic explanatory diagram showing one embodiment of the method of the present invention,
FIG. 2 is a diagram showing the relationship between the N concentration in the Ar enriched gas and the Ar recovery rate in the PSA method. l... Ar usage setting W 2... Induced blower 3.
・・FI removal 4 machine 4・・To exhaust gas holder 12・・Compression a 6・・Adsorption device 7～7C・・Adsorption tower 8・Vacuum pump 9・・Automatic switching valve
10... Air molecules 11 device ■... Ar gas holder 13... Filter 14... Raw air compressor ■5... Heat exchanger 16... Expansion turbine
17... Air separation column 18... Crude ArkM
19... Tokogata Ar purifier 20... Dehumidifier
21...High purity Ar tower 22...Pure Ar purification process

Claims (1)

[Claims] In a method for recovering Ar gas from Ar-containing exhaust gas discharged from equipment that uses Ar, after the exhaust gas is adsorbed by a pressure fluctuation adsorption method to form an Ar-enriched gas, the
A method for recovering Ar gas, characterized in that the concentrated gas is introduced into a pure Ar purification step in an air cryogenic separation method to recover Ar gas.