Project Synopsis

Develop a process simulation template tool to aide in evaluating the capacities of different types of random packing in packed tower.

Project Summary

PACKED TOWER BASE SIMULATION TEMPLATE DEVELOPMENT

Process Engineering Associates, LLC (PROCESS) was contracted by a supplier of column packing to develop a simulation template to evaluate the capacity of packing products.  The simulation was developed in using PROCESS' licensed commercial computer simulation software CHEMCAD.  The simulation was established as a typical packed column model that could be utilized in numerous applications by changing the type of packing and feed conditions.  The initial scenario was an application involving MDEA to absorb carbon dioxide (CO2).  Packings were rated based on simulation results that compared mass transfer coefficients and pressure drop.  PROCESS optimized the CO2 removal by selecting various random packing types from the CHEMCAD packing data base.  This also resulted in the development of techniques for converging non-equilibrium (mass transfer) columns.

The column is initially simulated using a standard vapor-liquid equilibrium model using an appropriate thermodynamics package such as NRTL, Redlich-Kwong, UNIFAC or other approach that models non-ideal behavior.  After a converged column is obtained, the model is changed to a mass transfer approach that utilizes diffusion coefficients and packing-specific geometries to calculate mass transfer coefficients.  This removes the equilibrium assumption and is generally a more conservative and realistic approach for packed columns.

The Billet and Schultes packing parameters are used where available because they allow for liquid hold-up in the packing.  If Billet-Schultes parameters are not available, the modified Generalized Pressure Drop Correlation (GPDC) as described by Kister is used.  This method uses the empirically-derived packing factor (Fp) that is specific to each type of packing.  The packing factor method was found to be less accurate in predicting column flooding than Billet Schultes.

The simulation outputs were provided to the packing vendor as a deliverable to demonstrate the capability of the model to analyze packing performance.

Industry Type

  • Tower Packing Manufacturing

Utilized Skills

  • Simulation tool development
  • Packed tower design

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