When a vessel used in the process contains material and it is desired to move a portion or all of the batch to another vessel then the Transfer model is used for modeling the displacement emissions from the transfer. The emissions from a Transfer model are calculated exactly the same as for a Charge model. Select Transfer from the main program Add Step menu item. Once selected, the Transfer dialog window will appear on the screen for modeling specific information requirements. An explanation of the data entry fields and requirements are described as follows:
· Activity Title: A single line of text which provides a brief reference to the process step being modeled and which will be used by the program as a Title Page entry.
· Vent I.D. Field: If the vessel, condenser, or other control device vent contains a vent identification number or code, then this information may be entered in this edit field or selected from the drop down list from previous entries.
· Equipment: This button is used to access the Equipment Database to select a vessel or similar equipment item for use with this processing model. If this activity step was pre-existing and is only being edited, the program will prompt the user to determine whether it should simply use the selected vessel (with or without) the previous contents. The user may also select to have the program exchange the newly selected vessel in every step involving the original vessel.
· Link: Process activities may be configured to be linked or not linked when the process is recalculated. If this box is checked then the current activity will be re-evaluated during process recalculations. If this box left unchecked then the mixture definitions will remain unchanged during process recalculations. Occasionally, the process may contain a step that involves a chemical reaction or a liquid-liquid extraction. Under these conditions, the user may wish for the mixture composition to remain constant during the process recalculation.
· Subsurface: If this transfer operation is to be made in the process by way of a subsurface addition then the Subsurface box should be checked. However, if the charging operation is being made by way of above surface means (through a top nozzle such that the inlet liquid has direct exposure to the vessel headspace) then the Subsurface box should be left unchecked. The significance of this configuration setting determines how the vapor composition in the vessel headspace is calculated. An above surface addition will generally produce higher displacement emissions than a subsurface addition since the inlet stream has direct contact with the vessel headspace as the displacement is underway. See the users manual for additional information regarding the mathematics that are applied to each model.
· Duration (HR): Data entered in this field represents the amount of time that the filling process takes. For example, an entry of 1.0 hr will cause the emissions from this filling model to take place over a one hour period. The emission rate will be calculated by dividing the total emissions from this step by one hour. The expression may be entered in minutes (15 min) or hours (0.25 hr). A raw number (0.25) will be assumed by the program to be an entry in hours (0.25 will be converted to 0.25 hr).
Note that the user may also enter the flow rate for charging material to the vessel. For example, entering 10.0 gpm in the time field would cause Emission Master to calculate the charging time by dividing the flow rate into the volume of the material being charged. The final resulting time calculated by the program would be used for the charging activity. Entering 10.0 lpm in the time field would prompt Emission Master to calculate the charge time using liters per minute. Specifying a flow rate in the time field is limited to gpm or lpm units.
· Pressure (mm Hg): This entry represents system pressure of the process vessel during the filling operation. The default unit of measure for the system pressure is millimeters of mercury or mm. Hg. The program will allow input based on other units such as atmosphere (atm), inches of water (in. H2O), or kiloPascal (kPA) but these units will be converted to mm Hg for use within the program.
· Purge/Sweep: Pressing this button will take you to the Purge/Sweep dialog window where the noncondensable gas and purge rate may be specified. If the rate is set to 0.0 scfh (standard cubic feet per hour) then the modeling will be performed using the gas specified as the noncondensable component in the emission calculations.
· Initial Contents: If this is the first time that a vessel is being used in the process then it will be shown as empty. However, if the vessel has been featured during an earlier step of the current process then the initial contents box will display the resulting mixture from its last operation. Press the Edit button to define a new mixture or to modify the existing one. Press the Clear button to reset the initial contents to be empty. Press the Mix DB button to copy a mixture from the currently connected Process Database .
· Transfer From: This is the main interface for configuring Emission Master with the inlet stream contents to be transferred into this vessel from a remote vessel.
[Transfer] Press Transfer to access the Vessel Source Selection interface and to configure the transfer model with the material to be transferred into this vessel.
[Edit] Further define an incoming stream to be transferred by pressing the Edit button to access the Mixture dialog box. Once the inlet stream has been defined in the Mixture dialog then a mixture summary will be displayed in the Transfer From box.
· Control Devices: A control device is an equipment item which, when installed in the process vent line, reduces the level of certain compounds in the final gas stream. Control devices are selected for the Filling model from the active Controls Database. The Filling Model allows for multiple control devices to become part of the venting scheme for the source vessel. Press the Controls button access the main Controls Database interface.
· Non-Emitting: Check the Non-Emitting box if this activity will not have any vent emissions. This condition can exist under certain processing operations. For example, filling a vessel using residual vacuum in the vessel or filling a vessel when the process vent is tied directly back to the original charge vessel. Other operations may involve charging material to an unvented vessel and allowing the pressure to build during the process.
· Comments: Comments may help to document specific details that the user would like to make for this model. Comments may be ented directly in the edit box or entered using the notepad like interface.