Water trapout tray

Figure 20-3 illustrates a typical water trapout tray scheme. The trapout pan itself is too small to make a decent separation between water and hydrocarbon. A mixed phase is drawn off and flows to a small drum (boot) located at grade. In the boot, a good separation is made between the two... 

A gas plant reboiled absorber is the most common example of a tower that requires a water trapout tray (Fig. 20-4). Water accumulates in such absorbers because they are not refluxed. In general, towers that run at low reflux ratios are most subject to internal water accumulation. 

If both calculation and observation confirm that water is settling out inside a tower, the operability of the existing trapout tray should be checked. If no trapout tray exists, one should be installed at the earliest opportunity. 

If substantial reflux is provided, one can be sure that the amine is well stripped before it is drawn off the reboiler trapout tray. The regenerator reflux rale (Ib/hr water) should be 10%-30% of the reboiler steam rate. To double-check stripping efficiency, pull samples of lean amine and reboiler feed. Both should have the same H2S concentration. Remember, H2S must be stripped out of the regenerator trays, not in the regenerator reboiler. This is important enough to repeat Keep a decent reflux rate in the regenerator to prevent reboiler tube corrosion. 

Sometimes, a distillation column will begin losing efficiency due to water accumulation on the trays or perhaps the bottoms product has turned cloudy because of moisture. If there is no trapout tray, try cooling off the tower s feed. This will reduce the moisture content of the hydrocarbon. 

Leaking amine water cooler, 103 Leaking drawoff trays, 23-25 welded trapout pans, 23-24 Leaking feed-effluent exchanger (glycol), 444-445... 

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