Abstract
In general, vacuum deaeration is in practical use for the prevention of the sea-water desalination plant from corrosion. In this paper, an experiment of deaeration from fresh water was conducted to examine the application of spray towers combined with liquid jet for vacuum deaeration.
Those towers used for this experiment were 2-2.6 meters high and 40-130 mm in diameter. The spray nozzles were single nozzles with 2-3 mm diameter and a multi-nozzle with 20 perforations of 2 mm diameter. The liquid flow-rate at the nozzle was varied from 0.7 m/sec to 12 m/sec, and the distance of liquid fall-down was varied from 0.1 m to 1.9 m.
The results were that the tower pressure, the length of the nozzle and the flow-rate of stripping steam caused no influence to the H. T. U. of the tower. Very small influence of the liquid flowrate at the nozzle on the H. T. U. was observed. On the other hand, the H. T. U. showed a remarkable increase when there was an increase in the distance of the liquid fall-down.
The relation between the H. T. U. and the operating conditions of the tower and the chracteristics of the liquid observed in this study, nearly agreed with J. Mada's dimensionless equation obtained by the absorption experiment of carbon dioxide. However, when the gas bubble entrainment caused by liquid fall-down was restrained, this relation was found to deviate from the equation. This meant that the disturbance by gas bubbles promoted deaeration. When a portion of the feed flashed, the influence on the H. T. U. was not so remarkable as in the vacuum deaeration in the packed tower.
From these results, it was considered possible to apply the vacuum deaeration by the spray tower combined with liquid jet to the sea-water desalination plant if in the plant some pressure drop was allowed, the distance of liquid fall-down made shorter, and the multi-stage splayed to the spray tower.
