Page 543 - Elements of Chemical Reaction Engineering Ebook

Chap. 19 Questions and Problems 51 3

(e) Explore this problem and describe what you find. (For example, can you plot
a form of R(7J versus G(T)?) (f,) Discuss what you believe to be the point of the
problem. The idea for this problem originated from an article by Ben Horowitz.
The endothermic liquid-phase elementary reaction
A+B-+2C

proceeds, substantially, to completion in a single steam-jacketed, continu-
ous-stirred reactor (Table P8-4). From the following data, calculate the
steady-state reactor temperature:
Reactor volume: 125 gal
Steam jacket area: 10 ft2
Jacket steam: 150 psig (365.9"F saturation temperature)
Overall heat-transfer coefficient of jacket, U: 150 Btul h . ft2. OF
Agitator shaft horsepower: 25 hp
Heat of reaction, AH:, = +20,000 Btullb mol of A (independent of
temperature)

TABLE P8-4
Component
A 5 C
Feed (lbmollhr) 10.0 10.0 0
Feed temperature (OF) $0 80 -
Specific heat (Btullb mol."F* 51.0 44.0 47.5
Molecular weight 128 94 -
Density (lb/ft3) 63.0 61.2 65.0
*Independent of temperature.
(Am: T = 199°F)
(Courtesy of the California Board of Registration for Profes-
sional & Land Surveyors.)

P8-5, The elementary irreversible organic liquid-phase reacti.on
A+B-+C

is carried out adiabatically in a flow reactor. An equal molar feed in A and B
enters at 27"C, and the volumetric flow rate is 2 dm3/s.
Calculate the PFR and CSTR volumes necessary to achieve 85% conversion.
What is the maximum inlet temperature one could have so that the boiiling
point of the liquid (550 K) would not be exceeded even for complete
conversion?
Plot the conversion and temperature as a function of PFR volume (i.e., dis-
tance down the reactor).
Calculate the conversion that can be achieved in one 500-dm3 CSTR and
in two 250-dm3 CSTRs in series.
Vary the activation energy lo00 < E < 30,000 (caUmo1) and heat of reac-
tion 2000 < IAHRd < 25,000 (caUmo1) to learn their effect on the PFR
conversion profile.
Discuss the application of the runaway reaction criteria. What value of T,
would you use to prevent runaway if K = 3 at T, = 300 K?