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Technical Articles
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| Condensation Control in Clarifier and Thickener Drive Units |
By James Hu, PE
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All clarifier and thickener drive units operate in extremely humid environment. As a result, the main gear housing acquires a significant amount of water due to condensation, which contaminates the oil and increases the oil level. In response to a request from the City of Columbus Water Treatment Plant , DBS developed a retrofitable condensation control unit (CCU) to reduce the amount of condensate formed in the gear housing.
On a pier-mounted drive unit, the final output gear is inside a gear housing, which contains oil for lubricating the final gear and bearing. Although a large diameter seal is always used, the moist air can still find its way into the gear housing. As the temperature drops below the dew point, condensate forms in the gear housing, drops in the oil, and settles at the bottom of the gear housing. The maintenance crew has to drain the condensate from the drive unit frequently to keep the oil free of water. The amount of condensate drainage is largely dependent on humidity level, temperature variation, and the seal conditions. If the condensate is not drained out in time, it can push the oil level up, causing poor lubrication at the lower portion of the gear or causing oil to leak out of the seal.
The CCU can effectively keep condensate out of the main gear bearing housing. It takes air from the surroundings, heats it up to reduce its relative humidity, and blows it into the main gear housing. The constant flow of non-saturated dry air will keep the moisture level inside the bearing housing below saturation level to eliminate condensation problem. It also keeps positive pressure on the seal so that the moist air would not come in through the seal.
The CCU is a standalone device that will mount on the inspection port of all DBS drive units. It requires no maintenance and has no interference with oil change. It significantly cuts down on the machine maintenance demand and increases oil life. The CCU is available for retrofitting existing drive units, and is a standard option for new drive units.
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