The formation of cross-linked aromatic rings can be reduced by lowering the coke drum pressure, raising the coke drum outlet temperature, improving the vacuum tower…
The yield of precipitated asphaltenes cannot be reduced because the asphaltenes in the coker feed will produce coke regardless of coke drum operating parameters.
Sponge coke is a mixture of needle and shot coke. The coke formed is spongelike in appearance, and has a dull, black cast. It is…
Needle coke is formed from condensed aromatic compounds. High boiling aromatic compounds (typically 950°F and higher) react in the coke drum by cross-linking the aromatic…
Shot coke is composed of precipitated asphaltenes. Asphaltenes are large hydrocarbon molecules that are dispersed in the lighter aromatic and paraffinic oils in vacuum residuum.…
Petroleum coke sold for fuel may have a high VCM; coke sold for calcining must have a low (10%—13%) VCM. Making coke too soft (high…
A refinery designed to run a 30° American Petroleum Institute (API) crude must unexpectedly switch to a 40°API crude. Sometimes, large amounts of natural gas…
Heat transfer in crude exchangers often declines because of tube-side fouling. The difference in crude preheat may be 50°F for a dirty vs a clean…
Crude oil contains various chloride salts. Some of these salts decompose in the furnace to produce hydrochloric acid. The HCI boils overhead in the fractionator…
One of the important functions of a crude unit is to meet the flashpoint specification for the jet fuel product. This is best done by…