| 摘要 |
PURPOSE:To make it feasible to recover hydrogen gas with high purity by a method wherein a hydrogen gas circulating system is formed while an air purging pipe and a reaction gas purging pipe are separated from each other on the downstream side of CVD furnaces. CONSTITUTION:Before starting operation, the air in CVD furnace 11 is exhausted from an air purging pipe 18 through the intermediary of another piping 13 and three way valves 4. Besides after finishing operation, the reaction gas in CVD furnace 11 is exhausted from a reaction gas purging pipe 20 through the intermediary of electromagnetic valves 19 and passing through a fan 21 and a scrubber 22. Through these procedures, hydrogen gas with high purity may be recovered preventing nitrogen hardly separated from hydrogen from intruding into a circulating system of hydrogen gas. |
