Dr. Lamm
Supplemental Instruction
Iowa State University / Leader: / Shawn V.
Course: / CH E 210
Instructor: / Dr. Lamm
Date: / 2-7-2016
Warm Up
Remember When…
In your own words, explain the difference between a continuous process and a batch process. Try to describe each process with an example.
In your own words, explain the difference between a transient and steady-state process. Why is it important to make the steady-state assumption for a process?
Practice Problems
Felder and Rosseau 4.46 p. 190
Mammalian cells can be cultured for a variety of purposes, including synthesis of vaccines. They must be maintained in growth media containing all of the components required for proper cellular function to ensure their survival and propagation. Growth media are prepared by blending a powder such as Dulbecco’s Modified Eagle Medium (DMEM) with sterile deionized water. DMEM contains glucose, buffering agents, proteins, and amino acids. Sometimes the growth medium can become contaminated with bacteria, which requires the use of antibiotics. The culture medium is also supplemented with fetal bovine serum (FBS), which contains growth factors for the cells.
Suppose an aqueous stream of cultured cells (SG = 0.90) contaminated with bacteria is split, with 75% being fed to a mixing unit to dissolve a powdered mixture of DMEM contaminated with the same bacteria found in the water. The ratio of impure feed water to powder entering the mixture is 4.4:1. The stream leaving the mixer is combined with the remaining 25% of the aqueous stream and fed to a filtration unit to remove all the bacteria that have contaminated the system, a total of 2 kg. Once the bacteria have been removed, the sterile medium is combined with FBS and an antibiotic mixture PSG (penicillin-streptomycin-L-glutamine) in a shaking unit to generate 5000 L of growth medium (SG = 1.2). The final composition of the growth medium is 66 wt% water, 11 wt% FBS, 8 wt% PSG, and the balance DMEM. Draw a completely labeled flow chart for this system.
Critical Thinking
You’re an engineer at a company and your supervisor needs you to evaluate a reactive process that she does not believe performs to process specification. The process is described below.
A stream of species A is fed to a reactor and combined with a recycle stream containing compounds A, B, and C. In the chemical reaction, one mole of A decomposes into 1 mole of B and 1 mole of C. The reactor has been said to have a single pass conversion of 0.25. However, after taking a sample you see that the composition of the outlet of the reactor indicates a lower single-pass conversion rate than expected. Think of all of the possible reasons why you might be observing a lower single pass conversion than expected.