ChE 4253 Design I Name:______

Mid-Term Exam, page 1 of 7

Open Book – Open Notes Exam

Problem 1______/20

Problem 2______/20

Problem 3______/20

Total ______/100

1.) 5 short answer problems – 4 points each.

a.) Assuming an annual interest rate of 7.8%, which costs more a 10 year long $1,250 annual maintenance contract or a new $12,000 pump after 5 years of service? (Ignore salvage values.)

b.) Determine the year 3 depreciation for a $20,230,000 (=CTDC) plant investment using a MARCS with a class life of 15 years.

c.) For the plant in b) above, there are sales of $1,320,000 and a cost of manufacturing of $550,000 (excludes depreciation). Determine the payback period (PBP) given a tax rate of 40.2%.

d.) For the plant in b) and c) above, what is the annual cost of maintenance, wages and benefits?

e.) A heat exchanger calculation in ProMax gives a required area of 100ft2 for thermo siphon boiling acrylonitrile (TBP=7C at 200 psig). Calculate the bare module cost (CBM) of a stainless-steel double-pipe version of this heat exchanger.

f.) Bonus Question: (extra 4 points) For the heat exchanger in e) above, what pressure drop is expected?

2.)  There are two reactions that can be used to produce acrylonitrile, AN.

C3H6 (propylene) + NH3 + 3/2 O2 à C3H3N (AN) + 3 H2O

and

C3H8 (propane) + NH3 + 2 O2 à C3H3N (AN) + 4 H2O

Determine which reaction is the best economically using gross profit analysis.

Data

MW / $/kg
propylene / 42.08 / $0.68
NH3 / 17.03 / $0.58581
O2 / 31.9988 / $0.22
propane / 44.1 / $1.1161
AN / 53.06 / $0.91
H2O / 18.01 / $0.0

3.)  For a nail polish remover product that consists of a 50/50 mole fraction mixture of toluene (C7H8) and methyl ethyl ketone (C4H8O), we need to know if it will wet nails just after washing your hands in water.

Properties Toluene
Molecular formula C7H8 or C6H5CH3
Molar mass 92.14 g/mol
Appearance: colorless liquid
Density 0.8669 g/mL /
Properties Methyl Ethyl Ketone
Molecular formula C4H8O
Molar mass 72.11 g/mol
Appearance Colorless liquid
Density 0.8050 g/cm3 /
Properties of Water
Molecular formula H2O
Molar mass 18.01528(33)g mol-1 Appearance: colorless liquid [1]
Density 1000kg m-3, liquid (4°C)
Surface Tension at 25 C = 72.14 mN/m /


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