Question

Describe your solutions in detail, because partial credit will be given based on your work. If additional information is necessary in solving the problems, DO use your engineering sense and provide reasonable assumptions and explanations. You may use your calculator if necessary. Use a language of your choice. Note: The following information may be used. Gas constant, R-8.314 J(mol K)-8.314 kPa L/(mol K)-0.082 L atm/(mol K)-6.132 lbr ft/(gmol K)=1,987 cal/(mol K). Atomic mass of N-14; Atomic mass of O= 1 6; Atomic mass of S-32. Table 2. Typical cost of CSTR/batch reactors (2004) Price (US$) 29,000 Table 1. Typical cycle time for a batch process. Activity Charge feed to the reactor & agitate, t Heat to reaction temperature, t Carry out reaction, t Empty and clean reactor, tc Total time excluding reaction, frotal Volume Time (h) 5 gallons (18.9 liters) 50 gallons (189 liters) 500 gallons (1,893 liters) 1,000 gallons (3,785 liters) 4,000 gallons (15,141 liters) 8,000 gallons (30,283 liters) 0.5-1.0 0.5-2.0 38,000 70,000 85,000 150,000 (varies) 1.5-3.0 2.5-6.0 280,000 5. (30 pts.) The liquid-phase reaction, A+B- C, follows an isothermally in a flow system. The concentrations of the A and B feed streams are 2 M before mixing. The volumetric flow rate of each stream is 5 dm2/min, and the entering temperature is 300 K. The streams mixed immediately before entering. Two reactors are available. One is a gray 200-dm2 CSTR that can be heated to 77 °C or cooled to 0 °C. The other is a white 800-dm2 PFR operated at 300 K that cannot be heated or cooled but can be painted red or black. Note: k-0.07 dm/(mol min) at 300 K and EA=20 kcal/mol. elementary rate law and is carried out are (a) Which reactor and what conditions do you recommend? Explain the reason for your choice (for example, color, cost, space available, weather conditions, etc.). Back up your reasoning with the appropriate calculations. (b) How long would it take to achieve 90% conversion in a 200-dm batch reactor with CAo CB0=1 M after mixing at a temperature of 77 °C? (c) How long would it take to achieve 90% conversion in a 200-dm batch reactor with CAo CB=1 M after mixing at a temperature of 0 °C? (d) What conversion would be obtained if the CSTR and PFR were operated at 300 K and connected in series? (e) What conversion would be obtained if the CSTR and PFR were parallel with 5 mol/min to each? (f) What batch reactor volume would be necessary to process the same amount of species A per day as the flow reactors while achieving 90% conversion? You may keep Tables 1 and 2 in mind. operated at 300 K and connected in

Answer 1

Given > C A B phase vea ction lii each Shea m = 300 K En ingtemaperatire Reacho 2 PFR while CSTR Volume = g00 dm Volume ovdm i Design uation it> Yate laus -A KCACB it) Stoichionehry Ci-x) CAO v)lombine : 2malmo 3 - 2 k C-x)2 maomdin s mi/mia)» lo malníia 3 chm - ForAhemius eamation, find Kat T-350kK K(35Dx) 2000 1.987 D.oO 7 R 3 SD 300 2 8.45mmot, min K (350K) Solving for x omal/min Cx) oodm 2- Cmatn 8.d/mop. Min K Ap on yelving D.92 X

FDPFR dx Desig aation Rala laus -Y K h e i>Sto ichiomehny: CA ニ GCI-X tom bine V 2 dX Ao Va (1-X) -X) mom Fn=lomatnin 3 Cro VPFR 800 dm K o.07 dr/mal min Nou We CSTR woukd tonveon The be chosn for Satch reautos: NAO Dengn Eation K Rate lau T Stoichiomety Cix) ) CB CA We enation -h combinig k- X = KCAP p 2- k -x2 Belviogy dx dx , kc, G-x) V.-X2 X (J -X) Ko

) (mam) (-0.9 8.4 mol' mio |. 0S min Time trken the the dame eapation in Uticg 心 used at T='273K. Vahie co - x2 (kC kamation 2000 0 8.4S Xp K C273 k) 273 350 1-987 -3 dmmot min X 2.5chys 3543 min