Carbon Residue, Basic Sediment and Water, and Salt Content

Carbon Residue, Basic Sediment and Water, and Salt Content

Carbon Residue

Carbon residue (as % wt of crude oil, or crude oil fraction) is determined as the weight of solid residue remaining after heating crude oil to coking temperatures (700-800°C). Two standard tests with slightly different procedures are used to measure carbon residue: ASTM D524 Ramsbottom Carbon Residue (RCR) and ASTM D189 Conradson Carbon Residue (CCR). Carbon residue relates to asphalt (or asphaltenes) content of oil and indicates the tendency of fouling in heater tubes and catalyst deactivation. The higher the carbon residue, the higher is the coking (fouling) propensity of crude oil.

Basic Sediment and Water (BS&W)

The standard method ASTM D4007 is used to measure the amount of suspended inorganic solid particles and water (BS&W) in crude oils. These contaminants are mixed with the oil during production, and high concentration of BS&W causes operational problems in a refinery.

Salt Content

Salt content of crude oils can be measured using the standard method ASTM D3230 and reported as lb NaCl/1000 bbl. Desalting (removing the salt) is necessary when NaCl content is greater than 10 lbs/1000 bbl. Such high salt contents lead to corrosion in distillation towers and other equipment.