Page 90 - Elements of Chemical Reaction Engineering 3rd Edition

62 Conversion and Reactor Sizing Chap. 2

7. Space time, t , and space velocity, EV, are given by

(S2-5)

UO
sv = - (52-6)
V
In evaluating space velocity, the entering volumetric flow rate is usu-
ally referred to standard temperature and pressure.
8. Other definitions:

LHSV = liquid hourly space velocity, h-'

GHSV = gas hourly space velocity, h-' at STP.

QUESTIONS AND PROBLEMS

The subscript to each of the problem numbers indicates the level of difficulty: A, least
difficult; D, most difficult.

In each of the questions and problems below, rather than just drawing a box around
your answer, write a sentence or two describing how you solved the problem, the
assumptions you made, the reasonableness of your answer, what you learned, and any
other facts you want to include. You may wish to refer to W. Strunk and E. €3. White,
The Elements of Style (New York: Macmillan, 1979) and Joseph M. Williams, Style:
Ten Lessons in Clarity & Grace (Glenview, Ill.: Scott, Foresman 1989) to enhance the
quality of your sentences.

P2-1A Without referring back, make a list of the most important items you learned
in this chapter. What do you believe was the overall purpose of the chapter?
P2-2A What if
(a) you needed to estimate the reactor volume necessary to achieve 98%
conversion using the data in Table 2-l?
Before solving (b) you were asked to use the data in Table 2-1 to calcuIate the CSTR reactor
the problems, volume at a temperature 100°C higher than the temperature at which the
state or sketch
qualitatively the data were taken?
expectedresults P2-3A Redo Example 2-7 for the cases when the intermediate conversions are
or trends. (a) 30%, and (b) 70%. The molar flow rate is 52 mol/min.
P2-4, The space time necessary to achieve 80% conversion in a CSTR is 5 h. Deter-
mine (if possible) the reactor volume required to process 2 ft3/min. What is
the space velocity for this system?
P2-5, There are two reactors of equal volume available for your use: one a CSTR,
the other a PFR. The reaction is second order (- rA = kC2 = kCio (1 - X)2),
irreversible, and is carried out isothermally.