Sadhana B Mahapatra

US Patent:

20020081259, Jun 27, 2002

Filed:

Dec 27, 2000

Appl. No.:

09/749201

Inventors:

Daniel Dershowitz - Columbus OH, US
Ryan Mears - Mesquite TX, US
Jay Schnaith - Powell OH, US
Curtis Dove - Colorado Springs CO, US
Sadhana Mahapatra - Bridgewater NJ, US
Kevin Wadsworth - Columbus OH, US

International Classification:

C01C001/00

US Classification:

423/352000

Abstract:

Commercial grade ammonia is purified for use in production of semiconductors by initially passing the liquid ammonia through a liquid phase oil separation system. This removes the vast majority of the impurities. The filtered liquid ammonia is then passed through a vaporizer which quiescently forms ammonia vapor and prevents entrainment of impurities within the ammonia vapor. The vapor passes through a vapor filtration system and subsequently to a bubble column. The bubble column is designed so that the bubbles are small enough and travel at a rate which ensures that any entrapped particle within the bubble will have time to migrate to the surface of the bubble and thereby pass through the liquid phase. The collected vapor is directed through subsequent vapor filters and is collected. If anhydrous ammonia is desired, the ammonia vapor is collected upstream of the bubble column.

US Patent:

20030108473, Jun 12, 2003

Filed:

Jan 22, 2003

Appl. No.:

10/349065

Inventors:

Daniel Dershowitz - Columbus OH, US
Ryan Mears - Mesquite TX, US
Jay Schnaith - Powell OH, US
Curtis Dove - Colorado Springs CO, US
Sadhana Mahapatra - Bridgewater NJ, US
Kevin Wadsworth - Columbus OH, US

Assignee:

Ashland Inc. - Covington KY

International Classification:

C01C001/02
F26B007/00

US Classification:

423/352000, 159/023000, 159/047100, 159/DIG004

Abstract:

Commercial grade ammonia is purified for use in production of semiconductors by initially passing the liquid ammonia through a liquid phase oil separation system. This removes the vast majority of the impurities. The filtered liquid ammonia is then passed through a vaporizer which quiescently forms ammonia vapor and prevents entrainment of impurities within the ammonia vapor. The vapor passes through a vapor filtration system and subsequently to a bubble column. The bubble column is designed so that the bubbles are small enough and travel at a rate which ensures that any entrapped particle within the bubble will have time to migrate to the surface of the bubble and thereby pass through the liquid phase. The collected vapor is directed through subsequent vapor filters and is collected. If anhydrous ammonia is desired, the ammonia vapor is collected upstream of the bubble column.