Ammonia Absorption into Water in a Packed Tower, VOF

Absorption of Ammonia into Water in Packed Tower, VOF, ANSYS Fluent CFD Simulation Tutorial

The present problem simulates the absorption of ammonia in the air inside an absorption tower using ANSYS Fluent software.

The adsorption process is one of the methods of separating the components of a gas mixture placed in the presence of a solvent (liquid phase). The basis of work in this adsorption process is the difference in solubility of the components in the gas phase.

Due to the contact of the gas phase with the liquid solvent, one or more gas phase components go to the liquid phase and separate from the gas stream. One of the applications of absorption towers in refineries is to separate ammonia from gas.

Airflow with one percent ammonia enters at a flow rate of 0.43 m/s from the nozzle at the bottom of the absorption tower chamber. At the same time, liquid water flows with a flow rate of 0.0332 kg/s from the nozzle at the top of the tower.

The interaction of ammonia in a gas stream with a stream of water as a solvent causes the absorption of ammonia by the water.

The present model is designed in three dimensions using Design Modeler software. The model is a vertical absorption tower So that the airflow with ammonia enters the tower chamber from the bottom nozzle and leaves the tower’s upper section.

The water flow enters the tower chamber from the top’s nozzle and leaves the tower’s lower section.

We carry out the model’s meshing using ANSYS Meshing software. The mesh type is unstructured. The element number is 478882.

Methodology

In this simulation, the VOF multiphase flow model is used; So that the airflow contains one percent ammonia and liquid water is considered a solvent.

Conclusion

At the end of the solution process, three-dimensional and two-dimensional contours related to pressure, velocity, vortex viscosity, density, water volume fraction, air volume fraction, and ammonia volume fraction were obtained.

The images show that the ammonia in the gas is absorbed by the water stream and separates the ammonia from the gas stream.