Corrosion and salt fouling in oil refineries
Ammonium salt fouling is an omnipresent threat in oil refineries. It may lead to insecure operational conditions with high production losses. Salt deposition is frequently detected in fluid catalytic cracking main fractionator columns. Higher chloride concentrations in residue feedstocks can initiate ammonium salt fouling. Low main fractionator top temperatures of fluid catalytic cracking units will increase the fouling risk. Negative impacts are increased pressure drop, flooding of the top section and production losses. Heat recovery is essential at process units, which are operated with reactors. Typical process units, where ammonium salt fouling or corrosion occurs are hydrotreaters, hydrocrackers and catalytic reformers. Feed/effluent exchangers of hydroprocessing units and the stabiliser columns are equally affected.
Kurita's ACF Technology prevents fouling and corrosion.
The new ACF (Ammonium Chloride Free) technology uses the benefits of a chemical programme. ACF additives are liquid formulations with a very high base strength. ACF reacts immediately with strong acids such as hydrochloric acid. The strong base ACF displaces the weaker base ammonium chloride or ammonium bisulfide from its salts. The ACF reaction products have a neutral pH and very low corrosion potential. Compared to that situation an ammonium salt has a very high corrosion potential.
The technology also incorporates a high moisture absorption property (very hygroscopic). ACF salts can absorb moisture from the surrounding steam to keep the formed ACF salts liquid. This prevents ammonium salt fouling and corrosion in crude distillation units, catalytic cracking units (FCC), hydrotreaters, hydrocrackers, reformer units and other process equipment.
The innovative treatment is based on several actions:
- The very strong organic base reacts immediately with strong acids by forming a liquid ACF chloride salt.
- Ammonia is released from the ammonium salt by forming the corresponding liquid ACF salt.
- The ACF reaction product has a neutral pH, is very hygroscopic and can be removed easily with water.
What are the benefits that ACF Technology offers?
Saves water
Less wash water is required to remove salt deposits with reduction of the corrosion potential.
Saves energy
By avoiding fouling on the tube bundles of heat exchangers, less energy is required to maintain the defined temperatures.
Easy to apply
ACF products are liquid formulations that can be easily added to the system to be treated using dosing pumps.
Economical savings
Improved system operation with economic savings for water & energy. Lower costs for repair or maintenance work.
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ACF - Expert Q&A
ACF (Ammonium Chloride Free) Technology is a patented organic strong-base chemical technology designed to prevent and remove ammonium salt fouling and corrosion in refinery and petrochemical processes. It converts corrosive ammonium salts into non-corrosive, liquid ACF salts that can be safely removed from the system.
ACF technology targets ammonium chloride (NH4Cl), ammonium bromide (NH4Br), ammonium bisulphide (NH4HS), and neutralising amine hydrochloride salts, which are known to cause fouling, corrosion, pressure drop, and heat-transfer losses.
Common locations include crude and vacuum distillation overhead systems, FCC and RFCC main fractionators, pumparound circuits, hydrocrackers, hydrotreater and reformer feed-effluent heat exchangers, Hydrocrackers, recycle gas compressors, stabilizers, burners, flare lines and safety valves.
Ammonium salts absorb moisture and form acidic, concentrated salt solutions that lead to under-deposit pitting corrosion, hydrogen blistering, and accelerated metal loss, especially on carbon steel.
Unlike filming amines or oil-soluble salt dispersants, ACF removes salts instead of relocating them downstream. Deposits are converted into liquid, hygroscopic ACF salts that remain fluid and are easily removed with sour water or condensed steam without re-depositing.
Yes. ACF can partially or fully replace caustic injection, reducing sodium load to downstream, avoiding catalyst poisoning, maintaining chloride control, and lowering neutralising amine consumption.
Yes. ACF is designed for online application during normal operation, eliminating the need for shutdowns or throughput reduction, mechanical cleaning, or extensive water washing.
The reaction is instantaneous. Small deposits can be removed within minutes, while larger deposits are removed progressively over hours or days depending on severity and dosage.
In many applications, ACF significantly reduces or eliminates water washing, avoiding acidic corrosion, off-spec production, and throughput losses.
Ammonium salt deposits are converted into liquid, hygroscopic ACF salts that remain fluid and are easily removed with sour water or condensed steam without re-depositing.
No. ACF salts have a neutral pH and very low corrosion potential compared with ammonium chloride or amine salts.
Yes. Continuous low-ppm dosing prevents salt precipitation by reacting with the incoming HCl.
Yes. ACF removes both ammonium-based salts ad deposited neutralizing amine hydrochlorides.
Benefits include lower pressure drop, productivity improvement, improved heat transfer, reduced corrosion rates, lower energy use, reduced chemical consumption, and improved catalyst life.
Yes. Deposit analysis is strongly recommended to select the correct formulation, dosing strategy, and ensure safe and effective treatment. ACF has no dispersant properties to remove already formed corrosion debris.
ACF has been applied in CDUs, VDUs, FCC and RFCC units, catalytic reformers, hydroprocessing units, fuel gas systems, flare lines, and safety valves.
No. ACF does not react with hydrocarbons. ACF reacts preferentially with acidic salts and it will not negatively impact product quality when properly applied.