Page 55 - Elements of Chemical Reaction Engineering Ebook

26 Mole Balances Chafj. 1

(a) After reading each page, ask yourself a question. Make a list of the most
important things that you learned in this chapter.
(b) Listen to the audios on the CD Lecture Notes and pick one and say
why it could be eliminat
What iE:
(a) the benzene feed stream in Example 1-4 were not preheated by the prod-
uct stream? What would be the consequences?
(b) you needed the cost of a 6000-gallon and a 15,000-gallon Pfaudler reac-
tor? What would they be?
(c) the exit concentration of A in Example 1-3 were specified at 0.1 % of the
entering concentration?
(d) the volume of the movable piston in Example 1-2 varied in a mannir
similar to a car cylinder, V = V,, + V, sin ot?
(e) only one operator showed up to run the nitrobenzene plant, what would
be some of your first concerns?
Calculate the volume of a CSTR for the conditions used to calculate the
plug-flow reactor volume in Example 1-3.
Calculate the time to reduce the number of moles ofA to 1 % of its initial value
in a constant-volume batch reactor for the reaction and data in Example 1-3.
What assumptions were made in the derivation of the design equation for:
(a) the batch reactor?
(b) the CSTR?
(c) the plug-flow reactor (PFR)?
(d) the packed-bed reactor (PBR)?
(e) State in words the meanings of -rA, -rA, and rA. Is the reaction rate
-r, an extensive quantity? Explain.
What is the difference between the rate of reaction for a homogeneous system, -rA,
and the rate of reaction for a heterogeneous system, -rd? Use the mole balance to
derive an equation analogous to Equation (1-6) for a fluidized CSTR containing cat-
alyst particles in terms of the catalyst weight, W and other appropriate terms.
How can you convert the general mole balance equation for a given species,
Equation (1-4), to a general mass balance equation for that species?
The United States produces 24% of the world‘s chemical products. According to
the yearly “Facts and Figures” issue of Chemical and Engineering News (C&E
News, June 24, 1996), the following were the 10 most produced chemicals in 1995:

Chemical Billions of Pounds Chemical Billions of Pounds
1. HzS04 95.36 6. NH3 35.60
2. NZ 68.04 7. H,P04 26.19
3. o* 53.48 8. NaOH 26.19
4. C2H4 46.91 9. C3H6 25.69
5. CaO 41.23 10. Cll 25.09

(a) What were the 10 most produced chemicals for the year that just ended?
Were there any significant changes from the 1995 statistics?
The same issue of C&E News gives the following chemical companies as the
top 10 in total sales in 1995. (Also see http:Nwww.chemweek.com)