Method for recovering and purifying argon gas from silicon single crystal manufacturing apparatus and apparatus for recovering and purifying argon gas

Patent metadata

Field	Value
Publication number	US-9890044-B2
Application number	US-201515109380-A
Country	US
Kind code	B2
Filing date	Jan 14, 2015
Priority date	Jan 29, 2014
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

An argon gas recovering and purifying method including: introducing waste argon gas containing nitrogen, oxygen, and carbon monoxide from silicon single crystal manufacturing apparatus into waste argon gas storage tank; removing solid matters in pretreatment facility which removes the solid matters in waste argon gas; converting oxygen into water and converting carbon monoxide into carbon dioxide by catalytic reaction; removing the water, the carbon dioxide, and the nitrogen to obtain recovered gas, in the argon gas recovering and purifying method and an argon gas recovering and purifying apparatus, the catalytic reaction is carried out with compression heat alone by arranging a catalyst in a two-stage compressor, and the water is removed by a dryer in advance and then the nitrogen and the carbon dioxide are adsorbed and removed in an ordinary-temperature adsorption tower at the step of obtaining the recovered gas.

First claim

The invention claimed is:

1. An argon gas recovering and purifying method comprising:
introducing a waste argon gas containing nitrogen, oxygen, and carbon monoxide from a silicon single crystal manufacturing apparatus into a waste argon gas storage tank;
removing solid matters in a pretreatment facility which removes the solid matters in the waste argon gas;
converting the oxygen into water and converting the carbon monoxide into carbon dioxide by a catalytic reaction; and
removing the water, the carbon dioxide, and the nitrogen to obtain a recovered gas,
wherein the catalytic reaction is carried out with compression heat alone by arranging a catalyst in a two-stage compressor, then the water is removed by a dryer and then the nitrogen and the carbon dioxide are adsorbed and removed in an ordinary-temperature adsorption tower at the step of obtaining the recovered gas,
in the converting, auxiliary oxygen is added to the waste argon gas while controlling an additive amount before a first-stage compression unit in the two-stage compressor, then one-stage compressing operation is performed, a temperature of the waste argon gas is increased to 100 to 200° C. by compression heat generated by the compressing operation, and then the carbon monoxide and the auxiliary oxygen are immediately subjected to the catalytic reaction in a first-stage catalytic unit installed behind the first-stage compression unit to convert them into the carbon dioxide,
the waste argon gas is cooled, and
hydrogen is then added to the waste argon gas while controlling an additive amount before a second-stage compression unit in the two-stage compressor to perform second-stage compressing operation, a temperature of the waste argon gas is increased to 100 to 200° C. by compression heat generated by the compressing operation, and then the oxygen and the added hydrogen are immediately subjected to the catalytic reaction in a second-stage catalytic unit installed behind the second-stage compression unit to convert them into the water.

2. The argon gas recovering and purifying method according to claim 1 , wherein the silicon single crystal manufacturing apparatus is directly connected to the waste argon gas storage tank through a waste argon gas pipe without installing a fluid carrying device so that a positive pressure is constantly maintained in order to prevent any portion in the waste argon gas pipe from having a negative pressure.

3. The argon gas recovering and purifying method according to claim 1 , wherein a heat source is not used in any unit other than the first-stage compression unit and the second-stage compression unit.

4. The argon gas recovering and purifying method according to claim 1 , wherein an intercooler is installed immediately after the first-stage catalytic unit and an aftercooler is installed immediately after the second-stage catalytic unit to cool the waste argon gas without providing a cooling device outside the two-stage compressor.

5. The argon gas recovering and purifying method according to claim 1 , wherein, at the time of introducing the waste argon gas into the two-stage compressor, a fixed amount of the waste argon gas is allowed to constantly flow through the two-stage compressor by constantly monitoring an intake pressure or a discharge pressure to a fluctuation in a flow volume of the waste argon gas at an inlet of the two-stage compressor to perform circulation control.

6. The argon gas recovering and purifying method according to claim 1 , wherein the dryer is a non-purge type dryer having a silica alumina base, activated alumina base, or synthetic zeolite base adsorbent.

7. The argon gas recovering and purifying method according to claim 1 , wherein the ordinary-temperature adsorption tower is a multi-tower type ordinary-temperature adsorption tower.

8. The argon gas recovering and purifying method according to claim 7 , wherein the multi-tower type ordinary-temperature adsorption tower is a three-tower type ordinary-temperature adsorption tower, and adsorption and removal of the nitrogen and the carbon dioxide in the waste argon gas, desorption of the adsorbed nitrogen and carbon dioxide, and pressure raising in the adsorption tower are alternately switched and repeated in the respective adsorption towers.

9. The argon gas recovering and purifying method according to claim 8 , wherein, at the time of performing the pressure raising in any adsorption tower in the three-tower type ordinary-temperature adsorption tower, an amount of the recovered gas used for the pressure raising is controlled in accordance with an inflow amount of the waste argon gas which flows into the adsorption tower by measuring the inflow amount.

10. The argon gas recovering and purifying method according to claim 8 , wherein times of the adsorption, the desorption, and the pressure raising are automatically changed in accordance with a fluctuation in a flow volume of the waste argon gas.

11. The argon gas recovering and purifying method according to claim 1 , wherein, when a level of the waste argon gas storage tank is lowered with a fluctuation in flow volume of the waste argon gas, a full amount of the recovered gas is automatically returned to the waste argon gas storage tank.

12. The argon gas recovering and purifying method according to claim 1 , wherein, when concentrations of the nitrogen, the oxygen, and the carbon monoxide in the recovered gas exceed predetermined allowable values, supply of the recovered gas to the silicon single crystal manufacturing apparatus is immediately stopped, and a part or all of the recovered gas is purged outdoors or returned to the waste argon gas storage tank.

13. The argon gas recovering and purifying method according to claim 1 , wherein, when concentrations of the nitrogen, the oxygen, or the carbon monoxide in the waste argon gas exceed predetermined allowable values at an inlet of the ordinary-temperature adsorption tower, supply of the waste argon gas to the ordinary-temperature adsorption tower is immediately stopped, and a part or all of the waste argon gas is purged outdoors or returned to the waste argon gas storage tank.

14. An argon gas recovering and purifying apparatus comprising:
a waste argon gas storage tank which receives a waste argon gas containing nitrogen, oxygen, and carbon monoxide from a silicon single crystal manufacturing apparatus;
a pretreatment facility which removes solid matters in the waste argon gas;
a two-stage compressor which has a catalyst arranged therein, the catalyst enabling a catalytic reaction of converting the oxygen into water and converting the carbon monoxide into carbon dioxide with the use of only compression heat generated by compressing the waste argon gas, the two-stage compressor comprising:
an oxygen flow volume adjuster which adds oxygen to the waste argon gas while controlling an additive amount;
a first-stage compression unit which performs first compression;
a first-stage catalytic unit which has a catalyst arranged therein and performs a catalytic reaction of converting the carbon monoxide into carbon dioxide with the use of only compression heat generated by the first compression;
a hydrogen flow volume adjuster which adds hydrogen to the waste argon gas while controlling an additive amount;
a second-stage compression unit which performs second compression; and
a second-stage catalytic unit which has a catalyst arranged therein and performs a catalytic reaction of converting the oxygen into water with the use of only compression heat generated by the second compression;

a dryer comprising an adsorbent which enables removal of the water; and
an ordinary

Assignees

• Shinetsu Handotai Kk

Inventors

• Matsushima Hideaki
• Onozawa Ichiro
• Yajima Wataru

Classifications

• C01B2210/0045

  Oxygen · CPC title

• B01D2258/0216

  from CVD treatment or semi-conductor manufacturing · CPC title

• C01B2210/0046

  Nitrogen · CPC title

• B01D2256/18

  Noble gases · CPC title

• C01B23/0015

  Chemical processing only · CPC title