Amine contaminants can be grouped into three distinct categories; (1) heat stable salts, (2) degradation, (3) inlet contaminants. All of these contaminant categories can typically be present in any given amine system at the same time, although the amount of each one can vary from insignificant to several percent.

1. Heat Stable Salts
Strong acid anions such as formate, acetate, thiosulfate, thiocyanate, and chloride can tie up an amine molecule to form a salt that is not capable of being regenerated by the addition of heat, and are thus referred to as Heat Stable Salts. Not only do they tie up the amine and thereby reduce the acid gas carrying capacity, but they are also considered corrosive.
2. Conversion Products
Conversion products are contaminants in solution that are derived from the breakdown of the base amine molecule itself, often irreversibly, to form totally different chemical species. Examples of conversion products are the ethylenediamine derivatives (THEED in the case of DEA), which can form when CO2, COS or O2 are in an amine system.
3. Inlet Contaminants

There are four major contaminants that can enter the amine stream alone with the inlet gas. These are:

  1. Injection Chemicals:   Corrosion inhibitors from upstream pipeline operations and amine system injections, such as anti-foam chemicals can concentrate in amine systems. While these chemicals are excellent in controlling operating problems, their injection into an amine system over the months and years between turnarounds can build up to a substantial percentage of the amine concentration. A large buildup of injection chemicals can eventually lead to fouling and can cause changes in solution physical properties, such as viscosity and mass transfer.
  2. Hydrocarbons:  Heavy hydrocarbons from natural gas streams can condense in the contactor, and lubrication oil from upstream reciprocating compression can build up in amine systems over time. These hydrocarbons can cause foaming, and at high enough concentrations can change amine solvent physical properties.
  3. Particulates:  Typical insoluble particulates include iron sulfides, metals from equipment corrosion, charcoal from amine filters, and catalyst fines from upstream units.
  4. Produced & Make-Up Water:  Fine mist carry-over from inlet separation or entrainment in the heavy hydrocarbon can introduces inorganic anions and cations into the amine system.  Also, if reverse osmosis quality water is not used as make-up water to the amine system, the contaminants in this water will build up over time.

CCR provides the Complete Acid Gas Removal Solvent Maintenance option to the industry.  By utilizing a CCR vacuum distillation solvent reclamation system to process the contaminated amine in your system, operators can gain the assurance that their amine systems are have ALL contaminants removed in a single step and that they will be operating at optimum efficiency because their solvent will be at or near virgin solvent specifications.

The following list shows the most common contaminants associated with specific amines.

List of Common Contaminants

Amine +O2 carboxylic acid forms of the Amine Organic HSS
Imidazolidone Degradation
Bicine Degradation
Sarcosine Degradation
+Inlet Contaminants Anions Inorganic HSS
Cations Inorganic HSS
Hydrocarbons Organics
Injection Chemicals Organics/Inorganics
MEA +CO2 oxazolidone OZD
hydroxyethyl imidazolidone HEI
hydroxyethyl ethylenediamine HEED
+COS diethanolurea
DGA +CO2 Bis hydroxyethyl ethoxy urea BHEEU
+COS bis hydroxyethyl ethoxy thiourea
DEA +CO2 hydroxyethyl oxazolidone HEOD
bis hydroxyethyl piperzine BHEP
tris hydroxyethyl ethylenediamine THEED
+COS monoethanolamine MEA
hyroxyethyl imidazolidone HEI
bis hydroxyethyl ethylenediamine BHEED
DIPA +CO2 hydroxymethyl propyl oxazolidone HMPO
MDEA +CO2/ O2/ Excess Heat ethylene glycol EG
hydroxymethyl piperzine HMP
diethanolamine DEA
triethanolamine TEA
bis hydroxyethyl piperzine BHEP
2-(Bis(2-hydroxyethyl)amino)acetic acid Bicine
2-(Methylamino)acetic acid Sarcosine

 

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