ChE 250

Spring 2000

Problem Set #5

Due Thursday, March 2

Read Sections 4.6-4.7 from Felder and Rousseau.

1. Do F&R problem 4.40 - ammonia oxidation

2. Do F&R problem 4.43 - chlorine manufacture

3. Do F&R problem 4.59 - ethylene oxide reactor

4. Your neighbors know that you are studying chemical engineering and have come to you for advice concerning the ooperation of their gas furnace. A "handyman" came to their door with an offer to check the performance of their furnace at no expense. The handyman explained that if the CO₂ content of the gases leaving the chimney is above 15%, the situation is dangerous to their health, violates city code, and can cause "chimney rot." He carefully took a sample of the gases leaving the chimney and reported that the gases contained 30% CO₂ on a dry basis. He has offered to arrange for the purchase and installation of a safe new high-efficiency furnace for a "bargain" price.

a) Suppose that they are burning natural gas. (We'll model natural gas as 100% methane, and model air as 79% (v/v) N₂, 21% O₂.) If the furnace is operating with 35% excess air, as suggested in the installation manual, what is your estimate of the mole percentage of CO₂ in the chimney gases (dry basis). What is your advice to your neighbors?

b) Other fuels that can be burned are listed below, with empirical chemical formulae. If each is burned with 35% excess air, determine the % CO₂ in the stack gases produced. Present your results in a table, and comment on the consequences for CO₂ emissions, greenhouse gas levels, and global warming.

Fuel Formula Use

Fuel oil (CH₂) _n industrial boilers

Coal CH_x (x ~ 0.9) electrical power plants, Victorian houses

Coke C steelmaking

Hydrogen H₂ fuel cells, prototype cars, space shuttles