The following table shows the meaning of the variables appearing in this tab, as well as their default values and their generally acceptable range. Note that due to the manner by which the variables are used by the sizing and costing equations, the range of acceptable values may be further reduced.
|
Variable |
Default Value |
Range |
|
|
||
|
○ Max Diameter (m) |
2.0 |
Positive |
|
○ Max Depth (m) |
4.0 |
Positive |
|
○ Max Volume (L) |
50000 |
Positive |
|
◙ Diameter (m) |
0.5 |
Positive |
|
◙ Depth (m) |
0.5 |
Positive |
|
◙ Depth / Diameter |
1 |
Positive |
|
● Volume |
0.0 |
Positive |
Symbol Key: ○ User-specified value (always input); ● Calculated value (always output); ◙ Sometimes input, sometimes output
The GAC Adsorber requires the use of a consumable. By default the selected consumable is a ‘Dft GAC Packing (G)’. The user may select the desired consumable for the column from the GAC Adsorber: Consumables tab.
In design mode, the column volume demand is specified by the packed-bed adsorption operations carried out as part of the (one or more) GAC adsorption (for gaseous streams) unit procedures hosted by the equipment resource. The software will size the column based on the largest demand on bed volume amongst all packed-bed adsorption operations executed in the equipment resource. Once the largest bed volume demand is determined, it is used to determine the design parameter according to the selected option for the design constraint:
● When a maximum diameter is specified, the depth is also specified and the diameter is calculated.
● When a maximum depth is specified, the diameter is also specified and the height is calculated.
● When a maximum volume is specified, the depth-to-diameter ratio is also specified and the depth and diameter are calculated.
If the calculated design parameter exceeds the maximum specification for that parameter then the software will assume multiple number of identical units (each with bed volume equally distributed) that are operated in parallel.
If the procedure operates in continuous mode, additional units are required for regeneration. Even though some packed bed adsorption units today can be equipped with a mechanism for continuous regeneration (this option is not available by the simulation model) the majority of adsorption beds operate in two phases: adsorption followed by regeneration; therefore they are inherently cyclic. However, most plants operating under continuous conditions will stagger extra units so that the adsorption step is performed continuously. The model employed here will automatically estimate the extra units that must be available in waiting mode for each unit in operation. The total number of units will be equal to the sum of the number of units in operation and the number of extra units. For more details on the calculation of the number of units in continuous mode, see Packed-Bed Adsorption: Modeling Calculations.
In rating mode, the bed diameter, bed depth, and the number of units in operation are provided by the user.
● Number Of Units in Simultaneous Operation; the number of units in operation that are required according to the largest demand on bed volume and the design constraint.
● Number Of Units; the sum of the number of units in simultaneous operation and the extra units that must be available to ensure continuous operation if the procedure operates in continuous mode. If the procedure operates in semi-continuous mode, the number of units is equal to the number of units in simultaneous operation. For more details on the calculation of the number of units in continuous mode, see Packed-Bed Adsorption: Modeling Calculations.
For more information on this equipment, see Granular Activated Carbon (GAC) Adsorber (for Gaseous Streams).
For information on the left-hand side variables and options, see Equipment Data Dialog: Equipment tab.