Oil Refinery Desalter Wash and Brine Water
Crude Oil contains many contaminants that must be removed before refining processes can be carried out. Typical contaminants are salts such as KCl, NaCl, MgCl and CaCl and solids such as sand.
The salts are removed by mixing wash water to the crude feed to a desalter vessel and assisted by electrolysis within the vessel itself. The wash water should be as clean as possible but is often steam condensate collected from other parts of the refinery, so pH should be monitored real time and wash water diverted to a sour water stripper or be otherwise treated should pH be out of spec.
The “cleaned oil” proceeds to the refinery for processing. The brine underflow from the desalter is directed to waste water treatment and from there either recycled or safely discharged into the environment.
Both the wash water feed and brine discharge are challenging measurements. Wash water can have a pH of 5.5 –7.0 and can be contaminated with Ammonia and Phenols. Temperatures can be >100°C. The brine effluent can contain sulfides, heavy metals, and oil plus sediment and sand – this mixture is often very abrasive and electrode erosion, fouling and poisoning is an ever present risk.
REFEX pH combination and separate reference electrodes have a patented NON-POROUS, ionically conductive interface that separates wash water and brine effluent from the electrode’s Ag/AgCl reference half cell and KCl electrolyte. This is 100% resistant to H2S and Ammonia poisoning and prevents electrode fouling.
REFEX sensors combine ultra-fast response to pH changes (prevents over/under shoot of pH setpoints) and extremely long-life (low maintenance) to provide real and measureable savings in terms of chemical costs and manpower/replacement parts.