and differentiating with respect to η and assuming that En+1 is large compared to 1 : àW _ ( l E)\nE an £>+>
K
'
Equation 2 can be used to compute the incremental amount of solute recovered from the last stage added. The only effect of variation in the extract still will be to raise or lower absolute recovery level in the extractor; but the optimum number of stages will not be affected. Passing to the extract still, two independent variables can be set. A design procedure might be to set a distillate composition (amount of solute remaining in the solvent) and compute an optimum distillation process to produce this. Annual cost of this optimum process is then added to the annual cost of additional product lost due to recycling of product in the solvent. This procedure is repeated for several distillate compositions until a minimum total cost is found. Finally, the solvent recovery process is optimized as mentioned previously.
specialists in
LIQUID SOLIDS
Niagara
separation
®
F I L T E R S
by C e n t r i f u g a l Extract i o n · Pressure Leaf and Continuous Vacuur or Pressure F i l t r a t i o n F i l t e r Media
Example
Design a process to separate 10,000 lb./hr. of 30 wt. % acetic acid in water using 85 vol. % ethyl acetate-15 vol. % benzene as a
CUT DOWNTIME! Adaptable, downtime. with speed automated
versatile NIAGARA FILTERS minimize Steady production line filtration and efficiency is attained with fully models of NIAGARA FILTERS.
SPEED . . . Save time and boost production with these NIAGARA advantages: fast wet or dry cake removal without manual labor; highest flow rates result of advanced hydraulic design. EFFICIENCY . . . Operating with process streams from 5 to over 1,000 gallons per minute, NIAGARA FILTERS can be adapted to automatically process hundreds of materials. Complete data in NIAGARA section of Chemical Engineering Catalog, or write Dept. IEN-460 for free bulletins.
TOWER
DIAMETER-FEET
Figure 3. Distillation costs as a function of tower diameter and distillate composition
A
Niagara
FILTERS
DIVISION
Of
American Machine and Metals, Inc EAST MOLINE,. ILLINOIS
Circle No. 4 on Readers' Service Card VOL. 52, NO. 4
·
APRIL 1960
51 A
