GIBBSim is an integrated environment, combining the best tools for your industrial modeling needs. With GIBBSim, harness a large body of accumulated knowledge to create a model with maximum fidelity:
- Actual measured data can be entered at any point in the model
- Algorithms for various different aspects of industrial simulation are available, in subsystems of the GIBBSim unified package
- A vast database of oil components covers most possible fluid combinations
- Phase equilibrium values from numerous published experiments are shipped with GIBBSim
- For various non-Newtonian liquids, viscosity data is available witin the system
In an easy and uniform way, create any required industrial model, and use the wide set of tools to make this model perfect.
Integrated usage example: rectification column
Modeling a rectification column is one of the most common tasks for industrial simulation. As an example, we use a column that separates the water solution of two alcohols: propanol and butanol.
(The example setting was taken from: B.A. Ross, W.D. Seider. Simulation of Three-Phase Distillation Towers. Computers and Chemical Engineering, vol.5, pp. 7-20, 1980)
The column consists of 12 (theoretical) plates; at atmospheric pressure, it separates 50 moll/h of the water solution of n-butanol (13 moll%) and n-propanol (22 moll%). This fluid is fed onto the plate number 5, at a temperature of 90.2 oC. It is also known that at the upper ent, the fluid yield is 29 moll/h, and that the reflux ratio is 3. We can build a graphical model of this column in GIBBSim:
The GIBBSim database contains the physical qualities of the propanol and butanol solutions. It also has sufficient experimentally measured data on the vapour-liquid equilibrium for both of them. We use the Equilibrium data management subsystem to process this data, and to produce the NRTL coefficients that model this equilibrium rather well:
| Mixture |
Aij, cal/mol |
Aji, cal/mol |
ALPHA |
| Water-1-Butanol |
2635.96 |
295.38 |
0.38 |
| 1-Propanol-Water |
303.57 |
1831.68 |
0.45 |
| 1-Propanol -1-Butanol |
-52.11 |
74.50 |
0.40 |
The system can output a graph so we can evaluate the precision of the model:
Next, we create a set of Components for this model. The NRTL coefficient values that were found before are now to be used.
After setting the various column properties, we can immediately start the calculation. The system will use the NRTL correlation model to produce simulation results.
The results are notably close to the published work that we cite. (The work itself, Ross&Segner, uses the Van Laar equation; it also cites another work, Block&Hegner, that uses NRTL modeling).
| Parameter |
[6], Ross & Seider |
[6], Block & Hegner |
GIBBSIM |
| Equilibrium model |
Van-Laar |
NRTL |
NRTL |
| Condenser temperature, K |
361.2 |
361.5 |
361.5 |
| Reboiler temperature, K |
365.5 |
365.8 |
365.6 |
| Top product (liquid) composition, molar parts |
|
|
|
| C3H8O |
0.353 |
0.349 |
0.352 |
| H2O |
0.616 |
0.62 |
0.617 |
| C4H10O |
0.031 |
0.031 |
0.030 |
| Condenser duty, W |
-1256 |
-1393 |
-1264 |
| Reboiler duty, W |
1330 |
1392 |
1260 |
| Liquid flow to reboiler, mol/hr |
143.6 |
137.9 |
134.9 |
| Heavy liquid flow to reboiler, mol/hr |
39 |
31.7 |
48.8 |
| Bottom product, mol/hr |
21 |
21 |
21 |
| Heavy liquid flow in the bottom product, mol/hr |
3.1 |
1.9 |
5.9 |
| Number of stages (from the bottom) that contain both liquid phases |
5 |
|
8 |