Transcript Staged Column Design

STAGED COLUMN DESIGN
K. M. Tanvir Ahmmed
Lecturer, ChE, BUET
TYPES OF TRAY
• Bubble cap tray : old
• Sieve tray : simple
• Valve tray : modern usage
BUBBLE CAP TRAY
BUBBLE CAP TRAY
• 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
BUBBLE CAP TRAY (CONT’D)
SIEVE TRAY
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
VALVE TRAY
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
VALVE TRAY (ONE-PIECE
VALVE)
VALVE TRAY
VALVE TRAY
VALVE TRAY (CAGED VALVE)
VALVE TRAY (CAGED VALVE)
VALVE TRAY (FIXED VALVE)
VALVE TRAY