Problem with wastewater stripping side-line extraction
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I’m a beginner and would like to ask some questions about side-line extraction. The operating procedure specifies a side-line extraction temperature of around 151 degrees, but it is currently around 162 degrees. What’s going on? Is the valve for drawing off the side line opened too wide? Currently, the valve opening is around 20. Also, regarding the side-line extraction ratio, could those who know about it explain it in detail?
In my opinion, one must not mistake the extraction from the side stream for the extraction of acidic gases; the principles behind these two processes are different. The side stream mainly extracts water vapor, which contains some ammonia, and generally, the amount extracted through the side stream constitutes a significant portion of the raw water volume. The side stream has a considerable impact on the tower; increasing the amount extracted through the side stream does not raise the temperature at the side stream outlet – rather, it should decrease. The reason is that the extraction through the side stream carries the heat from within the tower to the rear part of the tower, resulting in a significant drop in tower pressure. Although the temperature in the area below the side stream may rise temporarily when the extraction amount increases, the temperature at the side stream outlet will definitely decrease. If the temperature is so high, other parameters also need to be considered, such as whether the amount of vapor at the bottom of the tower is too high, whether the extraction of acidic gases is insufficient, and whether the cold feedwater volume is too low. The negative consequences of a high temperature at the side stream outlet include an upward shift in the ammonia concentration distribution within the tower, which leads to a decrease in the ammonia content in the material extracted through the side stream, making it difficult to obtain water that meets the required standards.
I ran into this problem as well; the explanation from the person above was very helpful. Thank you!
The side-line withdrawal temperature is highly dependent on the operating pressure of the tower; therefore, the operating pressure should be stabilized first.
What’s the temperature at the bottom of the tower? Is the temperature the same at the top and bottom? Is the gradient gone? Is the tray clogged?