Alkanolamines such as MDEA or DGA are solvents of common application 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 avoid that any carbon fines would go through.
Unidro has provided very large Lean Amine Filtration Units for highly demanding Clients.
Either a cartridge filter or a precoat filter is typically selected as lean amine pre-filter for solids removal.
In case of a cartridge filter, the disposable filter elements must be of a consistent material and type to cope with the solvent nature and temperature, and to remove the largest amount of incoming solids, whilst avoiding early exhaustion. Depending on solvent type, on operating conditions and on the solids concentration and size, Unidro can optimize the filter design and the filter elements selection.
In case of a precoat 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 precoating / service / cleaning cycle normally involves complex automatic loops with sequence ON/OFF valves operated by the control system.
Adsorbing the organic contaminants on a granular activated carbon bed allows to minimize foaming phenomena in the gas process plants.
When designing the filter, the nature of the fluid must be considered to establish an adequate contact time and to optimize the hydraulics.
An appropriate media selection ensures the right porosity to adsorb effectively the undesired molecules.
As prolonged operation may lead to the production of some carbon fines, a 5 micron-rated cartridge guard filter is normally installed downstream the Activated Carbon Filter.