Basic requirement for Ducting design ;
1. FD. Fan Capacity CFM, Cu.m/hr.
2. ID. Fan Capacity CFM, Cu.m/hr.
3. Exhaust gas Velocity. (Upstream – Loss in process – Downstream = less than atmosphere.)
4. Temp. Up stream – Down stream .
Please you see as simplify flow diagram attached. And put in data as much as possible that you have.