This mixture undergoes a number of work-up steps.
1. Condensation
2. Separation
3. Purification and Drying
Bromine-generating Step
Hot brine rich in bromine ion is input to the reaction tower from above, while chlorine gas and water are introduced from the bottom of the reaction tower. In the reaction tower an oxidation-reduction reaction takes place, generating bromine:
2Br-(aq) + Cl2(g) → Br2(g) + 2Cl-(aq)
It is necessary to heat the system to prevent the bromine from remaining in solution. Heating is provided by steam, which actually serves two purposes:
Heating of the reaction tower above 100°C (100°C –120°C).
Removal of the bromine from the solution (the steam carries the bromine vapors with it).
The gas mixture containing the bromine vapors, residual chlorine and steam rises to the top of the tower, while the liquid brine accumulates at the bottom of the tower. The tower is packed with suitable filling materials (rings or disks made from resistant materials) to increase the contact area and the reaction time between the gases and the solution.
Bromine Separation Steps
A mixture of hot gases containing bromine, chlorine and water vapor leaves the top of the tower. This mixture undergoes a number of work-up steps.