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Condensers, Direct Contact
Condensers, and Vacuum pumps.
Some control devices and
process equipment operate in such a way that contaminants
are removed from the exit vent stream by way of a phase
change from the vapor to the liquid. In most cases the
liquid consists of only a single phase, although two
separate liquid phases can be encountered.
When the control device (such
as a condenser, direct contact condenser, liquid ring vacuum
pump) operates due to a phase change from vapor to liquid then Emission Master
applies equilibrium and material balance considerations
to calculate an answer.
1. The material balance
around the equipment item is assumed to remain constant. The
process inlet streams (liquid and vapor) are equal to the
exit streams (liquid and vapor).
2. Single stage equilibrium
concentration between the exiting liquid and vapor streams
are maintained for all condensable components. For example,
if the process contains methanol, water, and ethanol then
the partial pressures in the exit vapor stream are
calculated to be equal to the vapor pressures in the exit
liquid stream. If the exit liquid stream contains two liquid
phases then these two liquid streams are calculated to be in
equilibrium as well.
3. Air, nitrogen, or other
non-condensable gases in the system are considered to exit
the equipment entirely through the exit vapor stream.
4. Emission Master enables
the user to specify activity coefficients for each compound
in the system for each liquid phase. This flexibility
enables the program to determine presence of two phases in
the exit liquid. |
