ITW Services - Heat Stable Salts Cleaning and Prevention

Heat Stable Salts Cleaning and Prevention

Heat Stable Salts (HSS) formation is a common issue in the Amine plants. Heat Stable Salts refer to amine salts of ionic species such as acetate, formate, oxalate, acetate, thiosulphate, thiocyanate and chloride, that are thermally stable and are not dissociated to any great extent in the regenerator.

These species originate upstream of amine units as acidic by- products of other refining processes, especially Fluid Catalytic Cracking Unit (FCCU) and Delayed Coking Unit (DCU) operations. Thiosulphate is the product of SO2 breakthrough in sulphur plant tail gas units. These acids are all stronger than H2S and CO2 and they react with amine in an acid-base neutralisation, resulting in the corresponding amine salts. HSS result in the following problems:

  • Irreversible consumption of amine and subsequent loss in acid loading capacity
  • Increased corrosion due to HSS penetrating the protective FeS layer on the metal surface exposing the metal to further attack. The salt anions appear to act as corrosion accelerators by displacing the iron sulphide film. Corrosion from heat stable salts occurs in the hot areas of the plant where there is ther are liquid and vapour phases present: the reboiler, reboiler outlet line, the regenerator column between the lean amine level and the bottom few trays.
  • Foaming, due to higher concentrations of corrosion derived particulates.
  • Fouling, due to corrosion products and salt deposition.

ITW can apply its proprietary technologies to provide Amine Unit Total Management. In particular ITW:

  • Applies proprietary chemistry to be continuously injected in the process, which prevents HSS formation
  • Applies Online Cleaning to clean equipment and restore plant performance, on a need basis, in 24 hours feed-out/feed-in

The combined ITW proprietary approach:

  • Keeps the Unit clean and avoids fouling thereby avoiding amine reclamation/replacement
  • Keeps the Unit’s performance at peak and avoids operating concerns/environmental uncompliance
  • Minimizes fouling (which is normally a very serious problem for all of the unit)
  • Minimizes corrosion
  • minimizes foaming
  • Minimizes filters load and filters cleaning (which may eventually be a serious and expensive operating problem)
  • Minimizes activated carbon replacement