Dirty Amine Ruins Operation

Running a sulfur recovery operation with dirty amine is analogous to deficit spending. You are borrowing against the future, but the day of reckon­ing will surely come.

The insidious aspect of circulating dirty amine is its erosive nature. Carbon steel is corroded by clean amine. However, the sulfide products of corrosion stick to the metal surfaces and inhibit further attack. Particulates in the circulating amine erode this protective layer. New metal is exposed to corrosion, then more particulates are generated as the corrosion-erosion cycle perpetuates itself. This environment is manifested by several signs.

Foaming. Dirt reduces the surface tension of liquids. Particulates will cause amine to foam. Foaming in regenerators results in high amine concentrations in the regenerator reflux water. Foaming in the scrubbers causes amine to be carried overhead with the hydrocarbon being scrubbed.

Plugged instrument taps. Flow rates in dirty amine systems tend to be erratic. Orifice taps on flow meters and level taps on float chambers often plug. Level control in the bottom of the scrubbers becomes unreliable and massive carry-overs of amine are frequent.

Condenser fouling. Rich amine regenerator feed splashes overhead. Particu­lates accumulate in the regenerator condensers, heat transfer is impaired to a certain extent, and the reflux temperature rises.

Reboiler tube failures. Enhanced corrosion rates are most evident in the regenerator reboilers. Dirty amine has caused tube failures after six months of service.

Filter plugging. The dirtier the amine, the shorter the filter life. The shorter the filter life, the dirtier the amine. For really had amine, filter pressure drop can increase 1 psi per hour.

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