Page 217 - Separation process principles 2

Table 5.4 (Continued)
Variable Specificationa
Case I, Case 11,
Component Number of
Recoveries Equilibrium
Unit Operation ND Specified Stages Specified
(f) Reboiled 2N + C + 3 1. Recovery of 1. Number of
stripping one key stages
(one inlet component 2. Bottoms flow
stream) 2. Reboiler heat rate
dutyd

(g) Distillation 2N+C+9 1. Ratio of vapor 1. Ratio of vapor
(one inlet distillate to liquid distillate to
stream, distillate liquid distillate
partial 2. Recovery of 2. Number of
condenser, Liquid light key stages above
partial component feed stage
reboiler, 3. Recovery of 3. Number of
both heavy key stages below
liquid and component feed stage
vapor 4. Reflux ratio 4. Reflux ratio
distillates) (> minimum) 5. Liquid distillate
5. Optimal feed stageb flow rate
(h) Extractive 2N + 2C + 12 1. Condensate at 1. Condensate at
distillation saturation saturation
(two inlet temperature temperature
streams, total 2. Recovery of 2. Number of
condenser, light key stages above
partial component MSA stage
reboiler, 3. Recovery of 3. Number of
single-phase heavy key stages between
condensate) component MSA and feed
4. Reflux ratio stages
(> minimum) 4. Number of
5. Optimal ' stages below
feed stageb feed stage
6. Optimal 5. Reflux ratio
MSA stageb 6. Distillate flow rate
(i) Liquid-liquid 2N + 2C + 5 1. Recovery of 1. Number of
extraction one key stages
(two inlet component
streams)

(j) Stripping (two 2N + 2C + 5 1. Recovery of 1. Number of
inlet streams) one key stages
component

ODoes not include the following variables, which are also assumed specified: all inlet stream variables (C + 2 for each stream); all element and unit
pressures; all element and unit heat transfer rates except for condensers and reboilers.
b~ptimal stage for introduction of inlet stream corresponds to minimization of total stages.
'For case I variable specifications, MSA flow rates must be greater than minimum values for specified recoveries.
d~or case I variable specifications, reboiler heat duty must be greater than minimum value for specified recovery.