Conradson carbon residue, commonly known as "Concarbon" or "CCR" is a laboratory test used to provide an indication of the
coke-forming tendencies of an oil. Quantitatively, the test measures the amount of carbonaceous residue remaining after the oil's
evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
and
pyrolysis
The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...
. In general, the test is applicable to petroleum products which are relatively non-volatile, and which decompose on distillation at atmospheric pressure.
The phrase "Conradson carbon residue" and its common names can refer to either the test or the numerical value obtained from it.
Test method
A quantity of sample is weighed, placed in a crucible, and subjected to destructive distillation. During a fixed period of severe heating, the residue undergoes
cracking and coking reactions . At the termination of the heating period, the crucible containing the carbonaceous residue is cooled in a desiccator and weighed. The residue remaining is calculated as a percentage of the original sample, and reported as Conradson carbon residue.
Applications
* For burner fuel, Concarbon provides an approximation of the tendency of the fuel to form deposits in vaporizing pot-type and sleeve-type burners.
* For
diesel fuel
Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and t ...
, Concarbon correlates approximately with combustion chamber deposits, provided that alkyl nitrates are absent, or if present, that the test is performed on the base fuel without additive.
*For
motor oil
Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, deterg ...
, Concarbon was once regarded as indicative of the amount of carbonaceous deposits the oil would form in the combustion chamber of an engine. This is now considered to be of doubtful significance due to the presence of additives in many oils.
* For
gas oil
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
, Concarbon provides a useful correlation in the manufacture of gas there from.
* For
delayed coker
A delayed coker is a type of coker whose process consists of heating a residual oil feed to its thermal cracking temperature in a furnace with multiple parallel passes. This cracks the heavy, long chain hydrocarbon molecules of the residual oil i ...
s, the Concarbon of the feed correlates positively to the amount of coke that will be produced.
* For
fluid catalytic cracking
Fluid Catalytic Cracking (FCC) is the conversion process used in petroleum refineries to convert the high-boiling point, high-molecular weight hydrocarbon fractions of petroleum (crude oils) into gasoline, olefinic gases, and other petroleum prod ...
units, the Concarbon of the feed can be used to estimate the feed's coke-forming tendency.
See also
*
Ramsbottom Carbon Residue
Ramsbottom carbon residue (RCR) is well known in the petroleum industry as a method to calculate the carbon residue of a fuel. The carbon residue value is considered by some to give an approximate indication of the combustibility and deposit formi ...
References
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Petroleum technology
Geochemical processes
Petroleum industry