Blending and distribution
After the refining processes, the various fractions are stored in intermediate
tanks, then blended into marketable products for loading onto railcars, trucks
or ships, and distribution to gas stations or industries.
Each product is blended to a specification of up to 25 parameters such as
octane rating, energy content, volatility and sulfur content. The task is to
achieve the specification (and not exceed, where applicable) with the
minimum amount of over-spec “giveaway.” The blending quality is managed
with infrared or chromatograph type process analyzers. These can
determine the precise fractions of a sample by molecule type.
The standard specification gasoline is therefore standard from company to
company in the individual markets, ensuring compatibility with vehicle
manufacturer requirements. Also, the terminal operator may be an
independent third party or run as co-distribution, so that a terminal in one
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region distributes for several companies based on the same products in the
same tanks.
Each company
then seeks to
differentiate its
product by adding
small quantities of
unique additives
that are marketed
to increase engine
performance,
lifetime, clean
combustion and so
forth. These
additives are
added as the
product is
dispensed to trucks
for delivery to that brand gasoline station.
A main task is to ensure the balance of incoming and outgoing products and
consolidate with stored volumes. These have to be compensated for
temperature,
water content (water may be absorbed from air humidity and
released at low temperatures as bottom slop in tanks) and vapor loss. Vapor
or volatile organic compounds (VOCs), form above the product in fixed roof
tanks and when filling up compartments in cars or vessels. VOC loss can be
significant for high volatility products like gasoline, and must be recovered
and/or handled to reduce emissions and explosive hazard.
The terminal management system tracks batches of product received or
dispensed, as well as those eventually received by gasoline stations, airports
or other consumers and consolidates with stored volumes. Each operation
should be validated against orders, bills of lading and positive identification
of trucks, vessels and their operators. In countries where this process is not
well managed, losses of product due to theft and other factors can be as
high as 15% or more in the distribution operations.
Eventually the main goal is to ensure that orders are met, and stakeholders
pay or get paid in the form of VAT, taxes, product, delivery charges,
etc.
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7 Petrochemical
Petrochemicals are chemicals made from petroleum or natural gas. Primary
petrochemicals are divided into three groups, depending on their chemical
structure:
Olefins include ethylene, propylene, and butadiene. Ethylene and propylene
are important sources of industrial chemicals and plastics products.
Butadiene is used in making synthetic rubber. Olefins are produced by
cracking.
Aromatic petrochemicals include benzene, toluene, and xylenes. Benzene
is used in the manufacture of dyes and synthetic detergents. Toluene is used
in making explosives. Manufacturers use xylenes in making plastics and
synthetic fibers. Aromatics are produced by reforming.
Synthesis gas (SynGas) is a mixture of carbon monoxide and hydrogen,
and is used to make the petrochemicals ammonia and methanol. Ammonia
is used in making fertilizers and explosives, where methanol serves as a
source for other chemicals
