Oct 4, 2015 - additional basis (Mass & Volume). Allow thermal condition of bubble point or dew point for reference streams. Gibbs Reactor - Support.
The initial set up is the same as cov ered in “Introduction to Pro II” so it will be assumed that the PFD is set up with the proper compon ents and thermodynamic package. Place the flash unit in the PFD space. Then press the “Streams” button and connect the feed stream to the left side of the flash drum and product streams to the top p ort and the side port. (Note: while it’s not critical to not connect the bottoms stream to the bottom port, the bottom port is normally reserved for decanted water or second liquid product.) Define the inlet stream S1 in the standard fashion described in “Introduction to Pro II.” Double clicking on the flash drum will open the specification window (shown below). Here the unit can be renamed by typing the desired name in the “Unit:” field, currently F1.
The flash drum will require two specifications. The first specification can be either: pressure drop, operating pressure or operating temperature. The second specification can be defined from the flash drum as: temperature (if pressure or pressure drop is selected as the first specification), pressure or pressure drop (if temperature is sel ected as the first specification), duty, dew point, bubble point, isentropic or upper dew point (if temperature is selected as the first specification). Alternatively, the second specification can be defined from the product.
To do this select the “Product Specification” radio button. In this window the parameter to be fit to in the selected stream can be chosen. This example is selecting composition of one of the product streams to be the parameter fit to.
The list of p ossible parameters is shown in the figure and also includes: transport propert y, heating value, distillation curve, refinery inspection property and user-identified special property. Once the parameter has been selected click “OK” to save the changes. The new parameter will appear highlighted in blue and the units that will be used are in green. If these are acceptable click “OK” again, if not either the parameter can be changed by clicking on it again, the units can be changed by clicking on them. Once the parameter has been set, the value can be set by clicking on “ value ” which opens a string field as shown below.
Enter the desired value into this field At this point the flash drum is sufficiently specified to solve properly. Note: if further specifications are made the system will become over specified and may not solve. Now the user ca n ca lc ul at e th e PF D by pr es si ng th e ic on or in th e “R un Pa le tt e. ” Th e sy st em will become colored blue if everything is able to be calculated. Results can be viewed as described in “Introduction to Pro II.”.
Screencast demonstrating the use of PRO/II process simulation software – using the Gibbs reactor unit operation. The model used solves the heat and material balances based on minimizing the free energy of the system. This gives a predicted composition based on the system coming to chemical and phase equilibrium. In reality, the feasibility of achieving this equilibrium composition depends on the actual reaction kinetics. However, the advantage is that the user does not need to supply any information about the reaction system.Presented by Dr Daniel Belton, Senior Lecturer, University of Huddersfield.