Supplemental Instruction
IowaStateUniversity / Leader: / German Parada
Course: / ChE 210
Instructor: / Lamm/Scheider
Date: / 09/19/2011
1) Explain the difference between gauge and absolute pressure.
2) What is the absolute pressure at the top and at the bottom of a cubic container (side of 2 m) full of honey (SG=1.36). Assume standard atmospheric pressure. What can you say about gauge pressures at the top and at the bottom?
3) The atmospheric pressure was 742 mmHg on a stormy day in Iowa. What would the pressure reading be at the bottom of a 30m water tank? The tank is 2/3 filled.
4) A small cylindrical tank (height=1m, radius= 40cm) is full of an unknown engine oil. The tank is 75% full, and the manometer at the bottom of the tank reads 6.36 kPa, gauge. Find the density of the oil.
What would the specific gravity of the oil be?
5) Calculate the molar flowrate of benzene of a stream that flows at 100 mL/s
6) Find the mass of a tank containing corn syrup (SG=1.360). The tank is 2.5 m high and has a diameter of 4m. What would the weight of the corn syrup be in Lbf
7) Explain the difference between accumulation and generation.
8) What is the relation between continuous and a steady-state processes?
9) Give an example of a batch, a continuous and a semi-batch processes.
10) Completely label the flow chart for the following process
A stream carrying 3 kg/min of butanol at 20C is mixed with 1 kg/min of a 40:60 mixture of isopropanol and butanol at 50C. The exit stream has an unknown composition and temperature.
Carry out a DoF analysis, and determine whether this process is specified or not
11) Wet corn starch containing one-fourth water by mass goes through an air dryer in which 90% of the entering water is evaporated. Find the mass of water evaporated and the mass fraction of water in the dried corn starch coming out of the evaporator.
a-Completely label a flowchart for the sugar drying process
b-Write a basis of calculation for the process.
c-Perform a Degree of Freedom Analysis for the process.
d-Write a system of equations for the process and outline an efficient procedure to solve for the unknowns in the problem.
e-How would the flow rates change if less air (or cooler air) was run through the air drier?
12)You have been assigned to design an extraction unit to recover benzoic acid from an organic phase (hexane as solvent) into an aqueous phase (water as solvent). Two streams enter the unit: Pure water, and 45 mol/s of a solution of benzoic acid in hexane. Two streams exit the unit: A benzoic-acid rich aqueous solution, and a depleted organic phase.
The mol fraction of benzoic acid in the incoming organic phase is 0.30, and the target for the leaving organic phase is 0.15, with the rest of benzoic acid in the aqueous phase. Assume water and hexane are immiscible. The partition coefficient of benzoic acid for the operating conditions is 8.0 (K = mol fraction in water/mol fraction in hexane). How many moles of water are required to carry out the desired extraction?
Create flow chart, carry out DoF analysis and write down equations, indicating how you would solve the problem
Discussion questions:
- How would the problem change if the incoming molar flow of water was specified instead of the desired molar fraction of benzoic acid in the outlet?
- Instead of benzoic acid, this unit will now extract a very valuable protein. Assume K has not changed. How would you maximize the mol fraction on the water stream? What are some possible issues with this approach?
13) Three parts of hot air coming from a spray drying process are mixed with 2 parts of air at ambient temperature. The hot air has water vapor content three times higher than the content in ambient air. Consider that the air is a simple mixture of “dry air” and water vapor. As a result of the mixing, 15 Liters of air come from the mixing unit every minute, with a water vapor content of 20 wt.% by mass. What are the flow rates of the hot air and ambient air streams?
a-Completely label a flowchart for the sugar drying process
b-Write a basis of calculation for the process.
c-Perform a Degree of Freedom Analysis for the process. Do not calculate anything.
d-Write a system of equations for the process and outline an efficient procedure to solve for the unknowns in the problem.