425
Introduction to Refining Processes
the continued demand for gasoline, and other fuels. Such a demand has been accompanied by the
demand for other products: diesel fuel for engines, lubricants for engine and machinery parts, fuel
oil to provide power for the industrial complex, and asphalt for roadways.
Unlike processes, products are more difficult to place on an individual evolutionary scale.
Processes changed and evolved to accommodate the demand for, say, higher-octane fuels, longerlasting asphalt, or lower sulfur coke. In this section, a general overview of some petroleum products
is presented to show the raison d’être of the industry. Another consideration that must be acknowledged is the change in character and composition of the original petroleum feedstock (Chapters 3, 8,
and 9). In the early days of the petroleum industry, several products were obtained by distillation
and could be used without any further treatment. Nowadays, the different character and composition
of the petroleum dictates that any liquids obtained by distillation must go through one or more of the
several available product improvement processes (Chapter 24). Such changes in feedstock character
and composition have caused the refining industry to evolve in a direction such that changes in the
petroleum can be accommodated.
It must also be recognized that adequate storage facilities for the gases, liquids, and solids that
are produced during the refining operations are also an essential part of a refinery. Without such
facilities, refineries would be incapable of operating efficiently.
The customary processing of petroleum does not usually involve the separation and handling of
pure hydrocarbons. Indeed, petroleum-derived products are always mixtures: occasionally simple
but more often very complex. Thus, for the purposes of this chapter, such materials as the gross
fractions of petroleum (e.g., gasoline, naphtha, kerosene, and the like) which are usually obtained
by distillation and/or refining are classed as petroleum products; asphalt and other solid products
(e.g., wax) are also included in this division.
15.15 PETROCHEMICALS
The petrochemical industry began in the 1920s as suitable by-products became available
through improvements in the refining processes. It developed parallel with the oil industry and
has rapidly expanded since the 1940s, with the oil-refining industry providing plentiful cheap
raw materials.
A petrochemical is any chemical (as distinct from fuels and petroleum products) manufactured
from petroleum (and natural gas) and used for a variety of commercial purposes. The definition,
however, has been broadened to include the whole range of aliphatic, aromatic, and naphthenic
organic chemicals, as well as carbon black and such inorganic materials as sulfur and ammonia.
Petroleum and natural gas are made up of hydrocarbon molecules, which comprise one or more
carbon atoms, to which hydrogen atoms are attached. Currently, through a variety of intermediates (Table 15.6), oil and gas are the main sources of the raw materials (Table 15.7), because they
are the least expensive, most readily available, and can be processed most easily into the primary
petrochemicals. Primary petrochemicals include the following: olefins (ethylene, propylene, and
butadiene) aromatics, (benzene, toluene, and the isomers of xylene), and methanol. Thus, petrochemical feedstocks can be classified into three general groups: olefins, aromatics, and methanol;
a fourth group includes inorganic compounds and synthesis gas (mixtures of carbon monoxide and
hydrogen). In many instances, a specific chemical included among the petrochemicals may also be
obtained from other sources, such as coal, coke, or vegetable products. For example, materials such
as benzene and naphthalene can be made from either petroleum or coal, while ethyl alcohol may be
of petrochemical or vegetable origin.
As stated earlier, some of the chemicals and compounds produced in a refinery are destined for
further processing and as raw material feedstocks for the fast-growing petrochemical industry. Such
nonfuel uses of crude oil products are sometimes referred to as its nonenergy uses. Petroleum products and natural gas provide two of the basic starting points for this industry: methane from natural
gas, and naphtha and refinery gases.
Introduction to Refining Processes
the continued demand for gasoline, and other fuels. Such a demand has been accompanied by the
demand for other products: diesel fuel for engines, lubricants for engine and machinery parts, fuel
oil to provide power for the industrial complex, and asphalt for roadways.
Unlike processes, products are more difficult to place on an individual evolutionary scale.
Processes changed and evolved to accommodate the demand for, say, higher-octane fuels, longerlasting asphalt, or lower sulfur coke. In this section, a general overview of some petroleum products
is presented to show the raison d’être of the industry. Another consideration that must be acknowledged is the change in character and composition of the original petroleum feedstock (Chapters 3, 8,
and 9). In the early days of the petroleum industry, several products were obtained by distillation
and could be used without any further treatment. Nowadays, the different character and composition
of the petroleum dictates that any liquids obtained by distillation must go through one or more of the
several available product improvement processes (Chapter 24). Such changes in feedstock character
and composition have caused the refining industry to evolve in a direction such that changes in the
petroleum can be accommodated.
It must also be recognized that adequate storage facilities for the gases, liquids, and solids that
are produced during the refining operations are also an essential part of a refinery. Without such
facilities, refineries would be incapable of operating efficiently.
The customary processing of petroleum does not usually involve the separation and handling of
pure hydrocarbons. Indeed, petroleum-derived products are always mixtures: occasionally simple
but more often very complex. Thus, for the purposes of this chapter, such materials as the gross
fractions of petroleum (e.g., gasoline, naphtha, kerosene, and the like) which are usually obtained
by distillation and/or refining are classed as petroleum products; asphalt and other solid products
(e.g., wax) are also included in this division.
15.15 PETROCHEMICALS
The petrochemical industry began in the 1920s as suitable by-products became available
through improvements in the refining processes. It developed parallel with the oil industry and
has rapidly expanded since the 1940s, with the oil-refining industry providing plentiful cheap
raw materials.
A petrochemical is any chemical (as distinct from fuels and petroleum products) manufactured
from petroleum (and natural gas) and used for a variety of commercial purposes. The definition,
however, has been broadened to include the whole range of aliphatic, aromatic, and naphthenic
organic chemicals, as well as carbon black and such inorganic materials as sulfur and ammonia.
Petroleum and natural gas are made up of hydrocarbon molecules, which comprise one or more
carbon atoms, to which hydrogen atoms are attached. Currently, through a variety of intermediates (Table 15.6), oil and gas are the main sources of the raw materials (Table 15.7), because they
are the least expensive, most readily available, and can be processed most easily into the primary
petrochemicals. Primary petrochemicals include the following: olefins (ethylene, propylene, and
butadiene) aromatics, (benzene, toluene, and the isomers of xylene), and methanol. Thus, petrochemical feedstocks can be classified into three general groups: olefins, aromatics, and methanol;
a fourth group includes inorganic compounds and synthesis gas (mixtures of carbon monoxide and
hydrogen). In many instances, a specific chemical included among the petrochemicals may also be
obtained from other sources, such as coal, coke, or vegetable products. For example, materials such
as benzene and naphthalene can be made from either petroleum or coal, while ethyl alcohol may be
of petrochemical or vegetable origin.
As stated earlier, some of the chemicals and compounds produced in a refinery are destined for
further processing and as raw material feedstocks for the fast-growing petrochemical industry. Such
nonfuel uses of crude oil products are sometimes referred to as its nonenergy uses. Petroleum products and natural gas provide two of the basic starting points for this industry: methane from natural
gas, and naphtha and refinery gases.