Materials and Energy Balances: Please explain and draw a picture! Solvent S is u
ID: 979555 • Letter: M
Question
Materials and Energy Balances:
Please explain and draw a picture!
Solvent S is used to extract a drug D from ground-up plant matter, but S must be recycled to cut costs. A fresh feed of pure S is joined with a recycle stream containing pure S at a different mass flow rate, and the combined stream is fed into an extractor, where it mixes with 1 kg/min D. The mixture of D and S leaving the extractor is fed to a separator. There are two streams leaving the separator. The first contains a mixture of D and S. The mass of S in this stream is 5% of the total S fed to the extractor. The second stream contains pure S, which is recycled and fed back to a point upstream of the extractor. If the stream directly into the extractor is 100 kg S/min, how much S must be fed into the process to maintain steady-state?
answer choices:
5 kg/min
10 kg/min
20 kg/min
50 kg/min
100 kg/min
200 kg/min
not enough information to be determined
Explanation / Answer
S extracts D
S---->D
S is recycled to cut cost.
S------>s
Mixture of D and S ---> 1 kg/min
The mass of S in first stream ---> 5%
The mass of S in second stream -----> 95%
The S in direct stream ---> 100 kg/min.
Steady state S --->?
Steady state, S = 100 kg/min x 5% = 5 kg/min