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Combustion |
A new type of
equipment record has been created in the
Emission Master database for entering
natural gas powered compressors,
electric generation equipment, and other
fuel burning equipment such as boilers.
A new combustion model
has been developed in Emission Master
that enables the user to select the
combustion equipment database, specify
the time period of operation and fuel
consumption (natural gas in this case -
SCF, MCF, or MMCF.)
The combustion model
also enables the user to specify
speciated emission factors in LB/MMCF,
LB/MCF, or LB/SCF units.
Once the new combustion model has been
completed by the user then Emission Master will calculate
the speciated emissions for the time period that has been
specified. The completed model may be saved for later
use and the calculated emissions may be easily exported in
the Emissions Accountant
database program from emissions inventory development and
tracking.
where: Ei
= amount of pollutant i from combustion
operation (lb, kg, tn),
Qfuel
= quantity of fuel consumed
during period of interest,
ei = amount of pollutant i emitted per standard
quantity of fuel consumed,
qfuel = standard quantity of fuel consumed (scf,
btu, mcf…).
View Online Tutorial |
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Depressurization |
Emissions
will occur as a process vessel is being placed under vacuum.
where: ni,out =
moles of volatile component i leaving the vessel
V = vessel headspace volume
pi =
partial pressure of the volatile component
R = Universal gas constant
T = system temperature
psys1 =
initial system pressure
psys2 =
final system pressure |
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Emission Factor Charge |
Factor Based Charge Model is for the special
cases where solids are processed. For example, it is a
common to charge activated carbon, filter aid, or other
powders to a process vessel. In the case of activated
carbon, the modeler may wish to declare and emission factor
that describes the emissions of activated carbon as a
fraction of the activated carbon that is being charged to
the vessel. The new Factor Based Charge Model easily allows
the modeler to create the required emission factor to use
for the calculation.
In another example, a finished powder product that is
partially wet with methanol is feed to a mill. The modeling
that might be required in this case is more complex because
the user is interested in expressing the emissions in terms
of (1) finished powder, (2) finished powder of PM10, and (3)
finished powder of PM2.5. Then there are the emissions for
the methanol portion of the charge material to calculate.
The new Factor Based Charge Model enables the user to create
a second emission factor for methanol that is completely
independent of the first one created to calculate
particulate emissions. If 90% of the methanol were
evaporated and emitted during milling then a factor for 90
lb Methanol / 100 lb Methanol would be created. The
composite emission factor model could then be saved in the
Factors Database to be used as needed. See
Emission Master Tutorial Page |
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Emission Factor |
Calculate emissions based on emission factors
that have been specified by the user using the new Factor
Based Model. this model could be used for complicated
operations such as evaporative losses, fermentation, and
other types of process operations.
where: Ei
= amount of pollutant i from combustion
operation (lb, kg, tn),
Qpr
= quantity of production during
period of interest,
e = amount of pollutant i emitted per standard
quantity of fuel consumed,
qpr = standard quantity of production (lb,
kg, hr, …). |
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Filling or Charging
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Calculate emissions resulting from
liquid transfers into a process vessel. |
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| Dilution Factor Mixing
Equations |
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Two examples are given below: (click on the
button to view a tutorial)
1)
Subsurface Addition with Methanol
2)
An above surface charge of water to an
empty vessel |
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Gas Evolution |
Calculate process emissions which
result when a reaction off-gas is generated.
where: Ei
= moles of volatile component i emitted
from the process,
Erxn
= total moles of reaction
off gas emitted from the process,
pi = partial pressure of volatile component
i,
prxn= partial pressure of the noncondensable
gas (i.e. air, nitrogen) at saturated solvent pressure
conditions. |
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Heating |
Vent losses from the vessel's gas space
are computed for when a batch is heated to a higher temperature.
where: ni,out =
moles of volatile components i leaving the vessel
process vent
Navg =
average gas space molar volume during the heating process =
pnc1 =
partial pressure of noncondensable in the vessel headspace
at temperature T1
pnc2 =
partial pressure of noncondensable in the vessel headspace
at temperature T2
ni,1 =
moles of volatile components in the vessel
headspace at temperature T1
ni,2 =
moles of volatile components in the vessel
headspace at temperature T2
Click
Here to watch an example video where a batch his heated
from 20C to 40C.
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Purging or Gas Sweep |
Estimate VOC vent losses when a gas
such as nitrogen is used to inert a vessel.
where: pi
= partial pressure of component i;
pnc
= partial pressure of noncondensable;
nnc
= moles of noncondensable;
si
= saturation level (1.0 = equilibrium
conditions)
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Empty Vessel Purge |
where:
Ei
are the moles of component i that are emitted due to
vapor displacement
pi,1
is the saturated vapor pressure of component i at
initial conditions,
V is the
gas space volume of vessel when empty,
R is the ideal gas constant in consistent units,
T is the temperature of the liquid being charged,
F is the purge gas flowrate,
t is the elapsed time for the purge operation.
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Reaction Model |
The Reaction Model enables the user to
specify a change in composition of a mixture through a
reaction, extraction, precipitation, or other process
phenomenon. Compounds that are removed from the process are
chosen from the current process mixture as Reactants while
compounds (or Products of the Reaction) that are formed from
the change are selected from the Chemical Database.
Stoichiometry for the reaction is entered in moles or weight
units (lb or kg). Reaction products can be designated to
form in any possible phase.
Emission Master scales the reaction based on the available
amount of each reactant and the stoichiometry. When the
reaction is implemented, Emission Master removes the scaled
quantity of each reactant and then adds the scaled quantity
of reaction product to the batch. Each reaction product is
placed in the phase that has been designated by the user.
The same reaction product may be designated for more than a
single phase which enables the Reaction module to support
extraction phase splits or crystallizations where the
compound coexists as a solid in a liquid with a partial
solubility.
Example reactions:
(1) HCl + NaOH -> NaCl (aq) + H2O (aq)
(2) 2 NaOH (aq) + 1 H2SO4 (aq) -> Na2SO4 (aq) + 2 H2O (aq)
(3) NaCl (aq) + AgNO3 (aq) -> NaNO3 (aq) + AgCl (s)
(4) Sodium Benzoate (aq) + HCl (aq) -> Benzoic Acid (s) +
Sodium Chloride (aq)
Example phase change:
(5) NaCl (s) -> NaCl (aq)
(6) NaCl (aq) -> 0.9 NaCl (s) 0.1 NaCl (aq)
(7) Ethanol -> 0.3 Ethanol (aq) 0.7 Ethanol (n_aq)
A nice feature of the Reaction Model is that
future changes and adjustments to earlier steps in the
process are supported. The reaction stoichiometry and
reactant quantities are dynamically evaluated during process
roll down recalculations. Therefore, changes in the
quantity or any of the reactants will be taken in account
each time the Reaction Model is calculated. See
Emission Master Tutorial Page |
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Solids Drying |
Determine solvent losses from drying
operations involving air transport style dryers. |
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Storage Tank |
Solvent storage tank calculations have
been adapted from E.P.A. literature and accommodate horizontal and
vertical vessels with air tight fixed roof styles. Normal breathing
and working losses are calculated. |
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Vacuum
Operation
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Once at vacuum conditions, the objective is to maintain vacuum
through the process operation. Vent losses stemming from vacuum
leaks in the equipment may be estimated.
where: Ei
= moles of volatile component i emitted
from the process,
Enc
= total moles of noncondensable
gas emitted from the process,
pi = partial pressure of volatile component
i,
pnc= partial pressure of the noncondensable
gas (i.e. air, nitrogen) at saturated solvent pressure
conditions.
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Mitchell Scientific, Inc.
PO Box 2605 Westfield, NJ 07091-2605, U.S.A.
TEL. (908) 654-9779 FAX:(908) 654-9788 |
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