Process for producing ammonia with ultra-low metals content
US6534027B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 2000 |
| Grant date | Mar 18, 2003 |
| Priority date | — |
| Expiry date | Jun 27, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01C1/024
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.