Documentation:CHBE Exam Wiki/Midterm Exam 2 2016W/MT2 Question 1

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CHBE 241
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Chemical and Biological Engineering
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This wiki is intended to host past exams

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Past Exams
Final Exam 2016W
Midterm Exam 1 2016W
Midterm Exam 2 2016W
Problem Sets
Module 1 - Process Basics
Module 2 - Reactors
Module 3 - Separations 1
Module 4 - Separations 2
Module 5 - Non-reactive Energy Balances
Module 6 - Reactive Energy Balances

Ethylene oxide is a widely used feedstock in chemical synthesis produced at rates of over 20 million tonnes per year. It can be produced by the oxidation of ethylene under a silver catalyst. This reaction also competes with the complete combustion of ethylene. A block diagram for an ethylene oxide plant is shown below, with the species indicated in each stream along with the reaction for the synthesis of ethylene oxide from ethylene.
Image for CHBE 241 MT2 Q1

Question 1a [5 points]

If the single pass conversion of ethylene is 40% when considering only the desired reaction for producing ethylene oxide, what is the exiting flow of ethylene oxide from the reactor (in kmol/s)?

Question 1b [10 points]

Considering both the desired and undesired combustion reaction now, the selectivity of ethylene oxide to CO2 formed is 2.28. What is the exiting flow of CO2 from the reactor (in kmol/s)?

Question 1c [20 points]

If the ethylene oxide (EO) scrubber removes 10% of the entering ethylene (E) and the CO2 scrubber removes 90% of the entering CO2, what is the molar recycle ratio (flow of recycle/flow of fresh feed) for this process?

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