Amine foaming is one of the most common upsets in gas treating units. When the amine solution foams, it is carried out of the absorber or regenerator, treating efficiency drops, and the unit can go off specification. In most cases foaming is a symptom of contamination, and cleaning up the contamination is the lasting fix. This guide explains the usual causes and where filtration fits.
What foaming does to an amine unit
- Liquid is carried over with the treated gas, which loses amine and can contaminate downstream equipment.
- Differential pressure across the column rises, and the unit may have to cut throughput.
- Treating performance becomes unstable, so the treated gas can drift off specification.
- Operators often respond by adding antifoam, which treats the symptom but can add its own contamination if overused.
Common causes of amine foaming
- Suspended solids. Fine particles such as corrosion products (for example iron sulfide) stabilise foam bubbles.
- Liquid hydrocarbons. Condensate or oil carried in with the feed gas disturbs the amine and promotes foaming.
- Amine degradation products. Heat, oxygen and reactions with contaminants create heat stable salts and other by-products.
- Foreign chemicals. Compressor oil, corrosion inhibitors, excess antifoam and poor-quality make-up water can all trigger foaming.
Where filtration and coalescing help
- Remove liquids from the feed gas. A gas phase coalescer ahead of the contactor captures liquid droplets and aerosols before they reach the amine. See liquid-liquid vs gas-liquid coalescers.
- Filter the circulating amine. Particulate filters on the lean and rich amine streams take out solids before they build up and stabilise foam.
- Remove hydrocarbons from the amine. Coalescing and separation elements help take free hydrocarbons out of the loop.
- Keep the elements maintained. Filters and coalescers only protect the unit while they are clean, so changeout intervals and differential pressure need monitoring.
Filtration works best together with good operating practice: clean make-up water, controlled antifoam use and a plan for investigating the source of the contamination.
Filters and coalescers from Power Energy Gulf
Power Energy Gulf provides filters, liquid and gas phase coalescers, phase separators and complete filtration skids for refineries, gas plants and petrochemical sites in Saudi Arabia and the GCC. See our amine system filtration and gas phase coalescers page, or send us the flow rate, pressure and contaminant for a recommendation.