C. Finally, this gaseous stream passes through a heater and then enters the dryer, thus forming the closed system indicated in the paragraph previous. a) Draw the block diagram for the process described, indicating both known and unknown quantities, using the appropriate symbols and corresponding units. b) Calculate the mole fraction of C6H6 in the gas streams leaving the dryer and condenser. c) As part of the cooler / condenser design
The benzene-moistened pigment enters a dryer at a rate of 8000 kmol / h and contains 1.25 mol% C6H6. The removal of C6H6 is not complete, so the pigment still has some of this solvent when it leaves the dryer. On the other hand, a flow of 9500 m3 / h of N2 enters the dryer, measured at standard conditions and in free base of C6H6, accompanied by a certain amount of C6H6 vapor. At the outlet of the dryer, the gas mixture N2 – C6H6 is at 768 mmHg and 42.2 ° C, with a relative saturation of 75%. This gaseous stream enters a cooler / condenser from which two streams are obtained: one of liquid benzene and the other formed by a gaseous mixture of N2 and C6H6 vapor. The latter is at 760 mmHg of total pressure and at the saturation temperature of C6H6. This stream then passes through a fan, emerging at 1250 mmHg of total pressure with a dew point of 15.4 ° C. Finally, this gaseous stream passes through a heater and then enters the dryer, thus forming the closed system indicated in the paragraph
previous.
a) Draw the block diagram for the process described, indicating both known and unknown quantities, using the appropriate symbols and corresponding units.
b) Calculate the mole fraction of C6H6 in the gas streams leaving the dryer and condenser.
c) As part of the cooler / condenser design, calculate the operating temperature of this unit, in ° C.
d) By analyzing degrees of freedom in the overall process and in each process unit, show that you have enough information to calculate all the molar flows. Explain your answer.
e) Calculate the molar flux of the liquid C6H6 recovered in the cooler / condenser and the production of wetted pigment leaving the dryer, both in kmol / h.
f) If the price of C6H6 is USD 760.57 for each ton, how much are the economic losses, in MXN2 per kmol of wetted product leaving the dryer, due to the content of C6H6 that was not recovered?
g) Propose at least two measures to fully recover C6H6.
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