In
a modern refinery setting, production processes are expected to be streamlined
to maximize value from beginning to end. Reducing waste is paramount, and
refineries should always examine their processes to ensure every product and
byproduct are optimized (FIG. 1).
One
of the byproducts most frequently seen in refineries is bitumen—a dense, large-molecule
liquid resulting from the traditional vacuum distillation of crude oil. Bitumen
is a key ingredient to make asphalt, which is frequently used in the construction
industry. Asphalt’s many uses include roads, runways, parking lots, roofing and
other applications. For many refineries, combining bitumen and aggregate to
produce asphalt can add value to their bottom lines.
Bitumen
is not uncommon, as it is produced in refineries everywhere; instead, its value
relies on its relatively low cost as a feedstock, and refineries usually sell
their excess bitumen to local asphalt plants. As a specialty product, asphalt
production carries higher profit margins than other bitumen uses.
Producing
this value from the bitumen byproduct means operators must regularly sample it to
ensure quality and consistency throughout the process. What makes bitumen
challenging to sample is that it is a high-viscosity fluid, making grab
sampling a more complex operation than with other fluids. Therefore, several things
must be considered when sampling bitumen or other high-viscosity fluids and
liquids.
Keeping the sampling system clog free.
Unless proper temperatures are
maintained, high-viscosity liquids may solidify. It is crucial to keep them
heated to at least 20°C
(68°F) above their
pour temperature to keep them in liquid form (FIG. 2). It is vital to design a sampling
system with the proper heating elements to keep the fluid flowing and prevent
clogs from forming when sampling at those temperatures. If a clog forms, it may
lead to a lengthy, messy and potentially dangerous cleaning process.
Keeping
the entire sampling system at or above minimum temperatures is critical, including
from the lines to the sampling point. Ensuring the system design is as simple as
possible allows operators to maintain consistent temperatures throughout. To that
end, systems should be well insulated to prevent cold spots, and designers should
avoid unnecessary components. In addition, a stinger nozzle—which uses a steam
jacket to keep the system media hot right up to where the sample is collected—is often incorporated.
Bitumen
sampling systems are particularly susceptible to clogs and are difficult to get
flowing properly again once the system is clogged. This requires completely
melting the system media already in the tubes, which is challenging. Cold spots
often develop in the system, preventing a full melting from taking place.
Mechanical interventions may become necessary, but they can be costly in
downtime and replacement parts. That is why preventing clogs from forming is
crucial to keep a system operating at peak performance.
Safe sample capture. Since the high-viscosity liquids in the tubes are often
significantly heated to keep them flowing, sampling them can pose potential
risks to the workers. Taking the necessary precautions to ensure operators can
sample these fluids safely is essential. Bitumen typically flows at
temperatures above 204°C
(400°F), meaning
contact with the fluid can cause severe burns.
Several
options are available to protect the workers sampling the liquids and prevent these
hazards from affecting work at a facility. For example, facilities can put in a
“no bottle, no flow” mechanism, which prevents the system from allowing any
liquid flow unless a container is in place. Not only can this mechanism keep
fluids from being dispensed accidentally, but it also prevents messes from
being created that can cost time and money to clean up. In addition, operators
should ensure the proper containers—typically made of metal—are used so the high temperatures do not damage
the container.
It
also may make sense to enclose the sampling point to keep accidental splashing
from injuring operators. The enclosure may also be steam-heated to prevent
clogs by keeping the media at the proper temperature.
Lastly,
using the right components in a bitumen sampling system is important to ensure
the increased temperatures do not cause inadvertent damage. The tube fittings,
valves and other system parts should be specified with the required temperature
ratings to accommodate the system media. A reputable supplier should be able to
advise on what components will work best for a system.
Have sampling specialists available.
Sampling plays a vital role in helping to
deliver the high-quality products that customers expect. After all, sampling
validates fluids composition, enables insight into following applicable
regulations and keeps the overall facility profitability at optimal levels.
It
is vital to work with a reputable supplier who can offer astute advice and provide
best practices for constructing and using sampling systems (FIG. 3). Suppliers should
be able to provide field engineers who can consult on sampling systems at all locations.
In addition, work with suppliers with the experience to handle niche fluids
like bitumen and other high-viscosity fluids. They can help design simple
systems that perform at maximal potential without the possible problems a more
complex system might entail. They should also be able to offer solutions to particularly
challenging sampling problems with onsite engineering advice. HP
MATT DIXON is the Application Commercialization Manager for Swagelok Company.