CHM ENG 140 Study Guide - Midterm Guide: Continuous Stirred-Tank Reactor, Chemical Engineering, Reaction Rate Constant

Consider a system with two CSTRs in series (i.e., the output from the first reactor becomes the input to the second reactor). Assume a pollutant enters the system and undergoes first-order decay with a rate constant k.

(a) What mean residence time, θ = V/Q, is required in the first reactor to achieve 90 percent removal in that reactor (i.e., C1/Cin = 0.1, where C1 is the steady-state outlet concentration for a fixed inlet concentration Cin)? Express your answer as θ = f(k).

(b) If the two reactors are designed so that a total of 90% removal is attained from the inlet of reactor 1 to the outlet of reactor 2, what is the mean residence time θ required for each tank? (The total system residence time is 2θ.) Express your answer as θ = f(k).

Four CSTRs of equal volume are to be used in series. The influent flow has a concentration of 170 mg/L of the compound A and the flowrate is 160 L/min. Compound A degrades is the system according to first order kinetics with a rate constant of 0.2 hr^-1. The system must achieve a removal efficiency of 95.3%. You must include the units when submitting your answer.

What is detention time for each reactor?

Determine the volume of each reactor?

If a single CSTR has a detention time equal to the total of the detention times for the four CSTRs in series, what will be the effluent concentration of A?

If instead of a single CSTR that has a detention time equal to the total of the detention times for the four CSTRs in series, you designed a plug-flow reactor (with this same volume), what will be the effluent concentration of A?