Alkanolamines such as MDEA or DGA are commonly used solvents in gas sweetening plants.
Treating a slip stream of the circulating lean amine prevents undesired contaminants such as suspended solids or amine degradation products from being accumulated in the circuit.
A lean amine filtration package would typically include three filters arranged in series: a pre-filter to remove suspended solids such as iron sulphides or oxides; an activated carbon filter to adsorb organic molecules generated by amine degradation; a guard filter to prevent any carbon fines from going through.
Unidro has provided large capacity Lean Amine Filtration Units for highly demanding applications.
Either a cartridge filter or a precoat filter is typically selected as the lean amine pre-filter for solids removal.
In case of a cartridge filter, the disposable filter elements must be of a compatible material to cope with the solvent properties and operating temperatures. This filter is responsible for removing the bulk of incoming solids while avoiding frequent maintenance. Unidro can optimize the filter design and the filter element selection depending on the solvent type, on operating conditions and on the solids concentration and size.
In case of a pre-coat filter, Unidro can propose a vertical filter with candle type filter elements or a horizontal filter with flat circular filter elements (“leaves”).
For both filter types, the pre-coating / servicing / cleaning cycle normally involves complex instrumentation loops with sequence ON/OFF valves operated by the control system.
Adsorbing the organic contaminants on a granular activated carbon bed minimizes the foaming phenomena in the gas process plant.
The nature of the fluid must be considered when designing the filter in order to establish an adequate contact time and to optimize the hydraulics.
An appropriate media selection ensures the correct porosity to effectively adsorb the undesired molecules.
A 5 micron-rated cartridge guard filter is normally installed downstream the activated carbon filter because prolonged operation may lead to the production of some carbon fines.