| 摘要 |
PROBLEM TO BE SOLVED: To provide a space-saving and cost-advantageous vacuum deaerator which is free from contamination by back flow and has high productivity and high efficiency (where dissolved oxygen concentration in ultrapure water is not more than 5 ppb). SOLUTION: This vacuum deaerator is provided with a vacuum deaeration tower having a packed bed and removing dissolved gas in a stock solution-to-be- treated by vacuum deaeration, a vacuum evacuation means for evacuating air from the vacuum deaeration tower, comprising a condenser installed in close vicinity to the inside or the outside of the top of the vacuum deaeration tower for condensing vapor of the stock solution-to-be-treated, piping for deaeration connected to the condenser, and a vacuum pump, a stock solution-to- be-treated feed means for spraying the stock solution-to-be-treated to the packed bed from above, a treated liquid storage part for storing the deaerated liquid, disposed on the bottom of the vacuum deaeration tower, and an inactive gas feed pipe for making an inactive gas flow into the upper space of the treated liquid storage part continuously at a volume flow ratio to the stock solution-to- be-treated of 0.001 to 0.5. In such a constitution, a condensate in the condenser is made to directly flow down into the vacuum deaeration tower.
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