CHEMICAL ENGINEERING CALCULATIONS PROBLEMS
1. Boron trichloride (BCl3) gas can be fed into a gas stream and for doping silicon. The
simplest reaction (not the only one) is
4BCl3 + Si → 3SiCl4 + 4B
If all the BCl3 not reacted is recycled, what is the mole ratio of recycled BCl3 to SiCl4 exiting
the separator? The conversion on one pass through the reactor is 87% and 1 mole per hour
of BCl3 is fed to the reactor.
, 2. Propane is dehydrogenated to form propylene in a catalytic reactor:
C3H8 → C3H6 + H2
The process is to be designed for 85% overall conversion of propane. The reaction products
are separated into two streams: the first, which contains H2, C3H6 and 0.656% of the propane
that leaves the reactor, is taken off as product, the second stream, which contains the balance
of unreacted propane and 5% of the propylene in the product stream, is recycled to the rector.
Calculate the composition of the product, the ratio (moles recycled/ moles fresh feed) and the
single-pass conversion.
1. Boron trichloride (BCl3) gas can be fed into a gas stream and for doping silicon. The
simplest reaction (not the only one) is
4BCl3 + Si → 3SiCl4 + 4B
If all the BCl3 not reacted is recycled, what is the mole ratio of recycled BCl3 to SiCl4 exiting
the separator? The conversion on one pass through the reactor is 87% and 1 mole per hour
of BCl3 is fed to the reactor.
, 2. Propane is dehydrogenated to form propylene in a catalytic reactor:
C3H8 → C3H6 + H2
The process is to be designed for 85% overall conversion of propane. The reaction products
are separated into two streams: the first, which contains H2, C3H6 and 0.656% of the propane
that leaves the reactor, is taken off as product, the second stream, which contains the balance
of unreacted propane and 5% of the propylene in the product stream, is recycled to the rector.
Calculate the composition of the product, the ratio (moles recycled/ moles fresh feed) and the
single-pass conversion.
