Plug Flow Reactor: Equipment Tab

Variable Definitions, Ranges and Default Values

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

◙ Volume The total vessel volume.	0.0 L	Positive
◙ Max Volume The maximum volume that a unit of this type is available for purchase in the market.	300,000 L	Positive
○ Length / Diameter The length over diameter ratio of the vessel	10.0	Positive
○ Max Allowable Working/Vessel Volume The maximum ratio of working (liquid) volume of material to total vessel volume allowed.	100%	(0,100]
● Length The internal length of the vessel.	0 m	Positive
● Diameter The internal diameter (or diameter equivalent) of the vessel.	0 m	Positive
○ Design Pressure The maximum pressure that the vessel has been designed to withstand.	1.52 bar	Positive
○ Is ASME Vessel? ASME standards of vessel construction will increase the cost of the vessel.	Yes	Yes/No

Symbol Key: ○ User-specified value (always input); ● Calculated value (always output); ◙ Sometimes input, sometimes output

Sizing: Design Mode

In design mode, the user specifies the max volume, and the program calculates the number of units and volume based on the volume demand that is specified by the operation carried out as part of the unit procedure hosted by the equipment resource. If that volume exceeds the maximum volume specification then the software will assume multiple number of identical units, each with a volume that does not exceed the max volume specification. From the vessel volume and the length-diameter aspect ratio, the actual dimensions of each vessel (length and diameter) are calculated.

To calculate the demand on vessel volume by the operation, the demand on liquid volume by the operation is divided by the operation’s working to vessel volume ratio. The equipment’s min and max allowable working to vessel volume ratio limits act as constraints on the operation’s working to vessel volume ratio (i.e., the operation’s working to vessel volume ratio must be within the range defined by the equipment’s min and max working to vessel volume ratio limits).

Sizing: Rating Mode

In rating mode, the volume of the vessel and the number of units are provided by the user. As in the design mode case, the actual dimensions of each vessel (length and diameter) are calculated from the vessel volume and the length-diameter aspect ratio. The program also calculates exactly as in the design mode case the demand on vessel volume by the operation carried out as part of the unit procedure(s) hosted by the equipment resource, and if the operation’s vessel volume demand of exceeds the actual vessel volume, it generates an error.

Costing

Equipment purchase cost is based on total vessel volume and material of construction. If the vessel is checked as an ‘ASME Vessel’ (i.e., constructed according to standards published by the American Society of Mechanical Engineers) then it is assumed to withstand pressure to 35 psig and its purchase cost is penalized by 20% over the base vessel cost. If the operating pressure of the vessel is set to a pressure higher than 3 atm, then the vessel’s purchase cost is penalized by an 80% increase over the base cost.

For more information on this equipment, see Plug Flow Reactor (PFR).

For information on the left-hand side variables and options, see Equipment Data Dialog: Equipment tab.