- Regenerative Thermal Oxidiser
- Thermal Recuperative Oxidizer
- Rotor Adsorption Systems
Anti Corrosion Fans
Complete Product Range
Solvent Separation Process Unit - Process Description
The solvent ladened process stream is collected from
the production plant and is first passed through the
absorption column. The absorption process is
performed under almost ambient conditions (1 bar
abs. pressure, approx. 20 degrees C) (401.4 inch water, 68F). A special
absorption liquid (also known as the re-circulating
liquid) is used for the absorption of solvent from the
process gas stream.
At the outlet of the absorption column, the solvent free
gas stream is directed to other production process
lines or discharged. The re-circulating liquid containing
high amounts of solvent is also discharged from the
absorption column and is directed to the next heat
The heat recovery step is aided by the use of heat
exchangers. The purpose of this step is to transfer the
heat from the re-circulating liquid that has been
discharged from the desorption column to the recirculating
liquid that has been discharged from the
absorption column. This has a dual purpose:
i) The first is to cool and prepare the recirculating
liquid from the desorption column for a new absorption
ii) The second is to heat the solvent ladened recirculating
liquid coming out of the absorption column.
This step prepares the liquid for treatment in the
desorber column. This heat exchange process takes
place in the Primary Heat Recovery Unit.
Downstream from the Primary Heat Recovery Unit are
two other heat exchangers. One is called the Heating
Load Heat Exchanger which further heats the solvent
ladened re-circulation liquid to the required 248F. The other is a Cooling Load Heat
Exchanger which cools the returning re-circulating
The solvent ladened re-circulating liquid from the
absorption column, now at 248F, is passed
through a flash unit. The pressure is reduced and part
of the solvent evaporates inside the flasher. The liquid
and solvent vapours are separated in the flasher and
directed to the desorption column separately. Inside
the desorption column the liquid and vapour phases
are treated separately. The desorption process is
performed under vaccuum conditions and at an
elevated temperature (approx. 100 mbar abs., 120
degrees C) (40.1 inch water, 248F).
In the lower desorption column the solvents in the recirculating
liquid are desorped (stripped) by aid of
steam. In the upper portion of the desorption column
the vapour phase undergoes a re-flux process to recondensate
the absorption liquid. This step ensures
that the absorption liquid does not evaporate together
with the solvent vapour. Downstream from the
desorption column, a twin condenser for the solvent
vapour is located before and after the vacuum pump.
The vacuum pump creates sufficeint suction pressure for the solvent ladened gas stream to pass
through the solvent separation unit.
Inside the condensers, the solvent is transformed back to a liquid phase and is then direceted
to the solvent separator. Located down stream from the condenser units is the solvent separator,
and as the term indicates, it separates the solvent fom the condensed steam. Solvent from this
separator is collected and either re-used in the production process or sold as a
At the end of the process, small amounts of air and residual non-condensed solvent are redirected
back into the inlet gas stream.
Examples of Application
Separation of solvent in gas refinary facilities.
Separation of solvent in the pharmaceutical industry.
Recovery of solvent at bulk filling terminals.