0.024 mol/mol.
The Stripper reboiler duty has been optimized to 85.5 Million Btu/Hr (21.54 Million kcal/hr) for each of the two parallel CO2
Strippers. Optimization results in a 4.0 percent reboiler energy reduction, to an improved energy use of 48080 Btu/LbMole
(26700 Kcal/KgMole) of CO2 removed. Lean solution circulation has been reduced in optimization by 8.5% to an optimized
flow rate of 3571 gpm (13.52 m3/min). The economic value of the CO2 Stripper reboiler savings would be approximately
$496,000 US Dollars per year, based on 350 days/year operation, 83% Fuel System efficiency and $7.00/MM Btu HHV
energy cost in the US. (July-Aug 2006) The sieve trays in the CO2 Absorber are calculated with Design II as operating at 70%
flood at the top tray and 90% flood at the bottom tray. The sieve trays in the Stripper columns are calculated as operating at
55% flood at the top tray and 85% flood at the bottom tray. Thus, another advantage of plant optimization is improving
equipment capacity.
needed to expand plant production. The plant illustrated in the Base Case aims to expand production capacity from 1550
STPD (1406 mt/d) to 1800 STPD (1633 mt/d) Ammonia production. The existing CO2 Absorber and CO2 Stripper columns
operate in the Base Case at very high percentage flood loadings with their existing tray internals. By defining revisions to the
column internals, it is possible to develop a heat and material balance for the desired higher production case, where the CO2
Absorber and CO2 Stripper columns will work, overcoming costly column equipment replacement. In this example, the trays in
the CO2 Absorber are replaced with two beds of random dumped stainless steel packing. The depths of packing for two beds
are selected to be 25 feet in for the bottom bed and 20 feet for the top bed. The packing for both of the beds is chosen as
Norton Type IMPT, 50 mm size. In the Stripper columns, the bottom 6 trays are replaced with new sieve trays having 11%
open area, increased from the original 7% open area.