Page 66 - Petroleum and Gas Field Processing

gravity indicates a lighter crude or oil product, whereas a low API gravity
implies a heavy crude or product.

Carbon Residue

Carbon residue is the percentage of carbon by weight for coke, asphalt,
and heavy fuels found by evaporating oil to dryness under standard
laboratory conditions. Carbon residue is generally referred to as CCR
(Conradson carbon residue). It is a rough indication of the asphaltic
compounds and the materials that do not evaporate under conditions of
the test, such as metals and silicon oxides.

Viscosity
The viscosity is the measure of the resistance of a liquid to flow, hence
indicating the ‘‘pumpability’’ of oil.

Pour Point

This is defined as the lowest temperature (5 F) at which the oil will flow.
The lower the pour point, the lower the paraffin content of the oil.

Ash Content
This is an indication of the contents of metal and salts present in a sample.
The ash is usually in the form of metal oxides, stable salts, and silicon
oxides. The crude sample is usually burned in an atmosphere of air and
the ash is the material left unburned.

Reid Vapor Pressure
The Reid Vapor Pressure (RVP) is a measure of the vapor pressure exerted

by oil or by light products at 100 F.

Metals
In particular, arsenic, nickel, lead, and vanadium are potential poisons for
process catalysts. Metal contents are reported in parts per million (ppm).

Nitrogen
It is the weight of total nitrogen determined in a liquid hydrocarbon
sample (in ppm). Nitrogen compounds contribute negatively to process
catalysts.

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.