1. STAGED COLUMN DESIGN K. M. Tanvir Ahmmed Lecturer, ChE, BUET

2. TYPES OF TRAY Bubble cap tray : old Sieve tray : simple Valve tray : modern usage

3. BUBBLE CAP TRAY

4. Advantages –flexible : operates satisfactorily at very high and low liquid flow rates Disadvantages –high entrainment: requires higher tray spacing –significant liquid gradient –problems with coking, high fouling mixtures –expensive –Poor turndown performance

5. BUBBLE CAP TRAY (CONT’D)

6. SIEVE TRAY

7. SIEVE TRAY (CONT’D) Advantages –easy to manufacture –inexpensive –considerable design information is available –efficiency is good at design condition –very good in fouling applications Disadvantages –turndown is poor (efficiency falls below the design condition) –not flexible

8. VALVE TRAY

9. VALVE TRAY (CONT’D) Advantages –better turndown ratio –more flexible –new industrial columns are more likely to have valve trays Disadvantages –Higher pressure drop than sieve tray –20% more expensive than sieve tray –more likely to foul or plug in case of dirty mixtures

10. VALVE TRAY (ONE-PIECE VALVE)

11. VALVE TRAY

13. VALVE TRAY (CAGED VALVE)

15. VALVE TRAY (FIXED VALVE)

16. VALVE TRAY