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Emission Master

Combustion | Depressurization | Factor Base | Filling | Factor Based Charge | Gas Evolution | Heating
Gas Sweep / Purge | Empty Vessel Purge | Drying | Reactions |Storage Tanks | Vacuum


 
AVAILABLE PROCESS MODELS
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

   
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

   

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 an 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 fed 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
   
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, …).

   
Filling or Charging Calculate emissions resulting from liquid transfers into a process vessel.
 
  • Empty vessel charge

  • Partially filled vessel charge
    - Above surface entry
    - Subsurface entry

Dilution Factor Mixing Equations

 

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

   
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. 

   
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.

   
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)

   
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.

 

   
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

   
Solids Drying Determine solvent losses from drying operations involving air transport style dryers.
   
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.
   
Vacuum Operation 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.

 


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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