Fluid Dynamics within FGD Plants

Project Number 202

The board of trustees of the VGB RESEARCH FOUNDATION granted a budget for an additional project for simulating the reaction of flue gas desulphurization (FGD) in scrubbers.

The new project on the fluid dynamical calculations will supplement the former reaction kinetic VGB projects 135, 159 and 186 which is being executed at Duisburg University until September 2000. Head of the new project 202 will be Prof. Fahlenkamp of Dortmund University. The project is supported and managed by the VGB Working Panel "Flue Gas Cleaning Technology". The new findings are to be combined with the reaction kinetic calculation model of the projects 159/186 (publication: VGB Kraftwerkstechnik (English edition), June 1997, p. 466 to 472).

Scrubbers installed in power plants, preferably single-cycle scrubbers, are to be operated efficiently. The requirement for scrubbing efficiencies of 95% and > means enormous optimization efforts.

The project is aiming at the exact reproduction of the flow in SO₂ scrubbers by taking into account the material exchange. A commercial CFD programme is used for simulation which is adjusted to the flow in flue gas scrubbers. The following phenomena are considered when modelling the system:

• droplet loss and reduced droplet concentration,
• effect of secondary suspension for improving the efficiency of atomization and material transition.

The complex fluid dynamic effects are taken into account by the calculation method which reveals the optimum flow ratio, i. e. the necessary L/G ratio for the flue gas scrubber. The modification of the flow conditions aiming at a large material exchange surface can improve the desulphurization degree by some percentage.

The project results permit engineering activities in order to achieve a removal degree

• at a possibly low circulation degree or
• to achieve an even higher desulphurization degree with a given installation if emission taxes have to be paid according to the remaining SO₂ emissions.