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Figure 12.5
Sensitivity study varying the water feed.
A sensitivity study was made varying the amount of water entering the process for
the purpose of determining the effect on the products and the composition and flow
rate of the reactor feed. The water feed rate was varied from 3 to 15 lbmol/hr. The
results are shown in Figure 12.5. The variables are defined below.
• H2PROD is the mole fraction hydrogen in stream 9.
• ORGPRD is the flow rate of water in lbmol/hr in stream 12.
• FLOS6 is the flow rate of stream 6 in lbmol/hr.
• XH2OS6 is the mole fraction of water in stream 6.
• XH2OS9 is the mole fraction of water in stream 9.
After about 13 lbmol/hr of water fed per 100 lbmol/hr of ethylbenzene, the material
balance is unstable.
1. The mole fraction of water in stream 6, the reactor feed (variable XH2OS6),
varies from about 0.011 to 0.074.
2. The mole fraction of water in stream 9, the hydrogen product (variable XH2OS9),
varies from 0.023 to 0.11, which corresponds to a change in the composition of
hydrogen (variable H2PROD), varying from 0.97 to 0.88.
3. The total reactor feed flow rate (variable FLOS6) varies from 284 to 327 lbmol/hr.
4. The flow rate of the organic product varies very little; however, rigorous distil-
lation has not yet been implemented.
The question of how much water to use in the process must be reviewed in light
of the foregoing results. Assuming that it is desired to produce as pure a hydrogen
product as possible, the remainder of the analysis will use a 3-lbmol/hr feed of water,
