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Low Temperature Thermal
Desorption (LTTD) – Direct Heated
Operating at
our Bedford facility since 1995, our Low Temperature
Desorption Unit is capable of treating hydrocarbon-impacted
soil at a rate of 35-40 tonnes per hour, at an
average concentration of 2.5 - 3%. Since being
commissioned, over 600,000 tonnes of hydrocarbon-contaminated
soil has been treated to non-detectable levels.
The thermal unit is fuelled
by recycled waste oil. This practice of reusing
a common waste product (crank case oil) is in
keeping with our efforts to remain vigilant and
employ whatever strategies are necessary to help
enhance the environment. Of course, other fuels
may be used if they prove to be acceptable and
beneficial.
Our Low Temperature Thermal
Desorption (LTTD) has been designed and constructed
to effectively purify soils contaminated with
various organic contaminates including: petroleum
hydrocarbons, pesticides, PAHs, and chlorinated
compounds. The system is designed to be both versatile
and highly portable.
The system is based on the concept of Low Temperature
Thermal Desorption (LTTD), which is the process
of contaminant removal by transforming contaminants
from one phase to another. The system targets
an operational temperature which is slightly greater
than the highest boiling point of the compounds
under treatment, but less than the auto-ignition
temperatures. As the soil is heated to this point,
the contaminants reach their respective boiling
points at which time the compounds vaporize and
become part of the gas stream. This removal mechanism
is physical transfer from the liquid phase to
the vapour phase.
The gases are then removed by negative pressure
and routed into a secondary combustion chamber
where they are further heated to a point above
the auto-ignition temperatures of the specific
compounds. The result of this process is a transformation
of organic compounds into carbon dioxide and water.
The gas stream, now consisting primarily of carbon
dioxide and water, enters a evaporative cooling
chamber (ECC), where the gases are cooled prior
to the final exhaust gas treatment in the baghouse.
The particulate matter in the gas stream is intercepted
in the baghouse and returned to the soil discharge
system. The gases are discharged from the baghouse
stack, which has continuous monitoring.
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