Ergun Software for Bubbling Beds
Chemical Reaction Rate
Ergun Software can deal with two kinds of chemical reactions:
"Catalytic Reactions" : Kunii & Levenspiel or Wether's models are available for first order kinetics only. Special modules can be developed for industrial purposes where chemical kinetics are more complicated. In many cases (i.e., when the chemical reaction kinetics is not the limiting step) the problem can be treated as a first order reaction.
"Consumable Particles" : Shrinking core model, any kinetics - constant size particles. Conversion rates, as well as the details of calculation are given in a simple table. The kinetics of gas/solid reaction is acquired as a conversion/time table. Virtual expert helps the user to a better understanding of limiting steps.
The diagram beside shows the quite complicated calculations to be done (trial and error method) for the conversion rate calculation. Note that the gas/solid reaction kinetics depends on a number of interactive phenomena :
- Bubble / Suspension diffusion of the gas reactant (A).
- Bulk to surface of particle diffusion of the A molecules.
- Gas / Solid reaction kinetics at the surface of the particles
- The Residence Time Distribution of particles in the fluid bed reactor (the suspension phase is always considered as well mixed)
- Particle mean conversion rate needs to be integrated over particles size distribution (G in the diagram above).
Ergun Software performs all the above calculations in a few seconds. The "Virtual Expert" informs the user if any "Limiting Step" is predominant.
Ergun Design Technology
Algorithm used for "Consumable Particles" conversion rate calculation
Example of results window for "Catalytic Reactions"
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