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Part I

1. (20 Marks)

a) Ash wants to determine the bubble and dew point of a mixture of acetone, methanoland water. He intends to use the Ideal method to find those parameters. However, his

tutor is not happy with the method he used. Why? Name other possible methods thathe can use and describe them.

b) What are the differences between DSTWU column with a RADFRAC column.c) Compare the two component approaches and give an example of situation when these

approaches are used

Part II

1. (30 Marks) Eugenol is an allyl chain-substituted guaiacol. Eugenol is a member ofthe phenylpropanoids class of chemical compounds. It is a clear to pale yellow oily liquidextracted from certain essential oils especially from spices. Eugenol is used

in perfumeries, flavorings, essential oils and in medicine as a local antiseptic andanesthetic.

Figure 1 : Molecular Structure of Eugenol

a. Perform a Property Constant Estimation run based on following information:

Formular: C10H12O2Mass Density: 1.066 gm/ccMolecular weight: 164.2011 kg/kmol

Normal boiling point: 254 C

Antoine vapor pressure constants for 9 C< T < 253.2 C: P in mmHg.log10P=8.3157-2768.17T+256.135

Submit your Apsen File: Eugenol.bkp.

b. Setup a flowsheet model for a process feed stream which consist of 70 mol%

eugenol and 30 mol% propyl isobutyrate at 1 bar and 60 C. Assume ideal gas

law and Henrys law. Propyl isobutyrate is in Aspen Plus data bank.

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i. What would be the maximum temperature that the stream could be heatedto and be all liquid?

ii. What would be the minimum temperature that the stream is heated to and

be all vapors?

iii. What is the temperature at which the stream is 50%liquid/50% vapor?

iv. Plot the t-xy diagram of the system and verify your answers of i ), ii) andiii). Submit your Apsen File: Q2b-Eugenol.bkp.

v. Find the dew point of pure Eugenol at 1 bar and 60 C feed. Compare that

with the results of ii). Explain how to reduce the dew point of the mixture

of Eugenol and propyl isobutyrate at 1 bar and 60 C.

Part II (Choose One)

1. Ammonia is essential for plant growth, metal treating operations, neutralization of acids atmine sites and pharmaceuticals. Common industrial Ammonia synthesis processes usesyngas feed stream. The objective of this reactor project is to design an ammonia synthesis

plant and find the optimum operating conditions which will yield more than 2100 kmol/hrAmmonia and minimum nitrogen percentage conversion of 95%. An example of AspenPlus flowsheet is given below. Peng-Robinson property method is recommended.

1

COOLIN

2

COOLOUT

3

VAPREC

PURGE

FEED COMPFEED MIXFEED

PRODUCT

COMPREC

H X

SPLITTER

COMPRES1 RGIBBS

FLASH

COMPRES2

MIXER

The following information is given:

N2+H22NH3

An adiabatic RGibbs reactor is operated at a pressure of 100 bar. The input feed stream

for the process is 5500 kmol/hr at 40 C and 2 bar at the following mole percentages:

74.2 mol% H2, 24.7 mol% N2, 0.8 mol% CH4, and 0.3 mol% Ar.

Isentropic compressor is used to increase the pressure of the mixed input feed stream and

recycle stream to 100 bar before entering the reactor.

The Tube & Shell heat exchanger following the reactor uses Ammonia at 2 bar, -40C

and 200kmol/s as the refrigerant to cool down the process stream. Pressure drop in both

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hot side and cold side are 100 bar. Shortcut calculation for the design type simulation

with hot and cold streams outlet temperature approach is 5 C. Accept other defaults.

The flash vessel is also operated at -30 C and had a pressure drop of 5 bar. The purge is

operated at 6% of the flash tops stream.

a. Report the outlet temperature of the reactor in C , the heat duties of the heat

exchanger and flash vessel in kW.

b. Report the percentage conversion of Nitrogen and generation of Ammonia.

Explain if the required objective has been met?

c. Setup a Sensitivity Analysis to examine the effect of the pressure of reactor on

the generation of ammonia in the product stream. What is the optimum operating

pressure which will yield the 2100 kmol/hr Ammonia.

Submit your Aspen File: Q2-Ammonia.bkp.

d. What are the required additional parameters if RPLUG has to be used instead of

RGIBBS?

4. A mixture of 150lb/hr containing 40.0 wt% acetone and 60.0 wt% water at 100F and

pressure of 50psi is to be separated into two streams one enriched in acetone and

the other in water. The separation process consists of extraction of the acetone from

the water into methyl isobutyl ketone (MIBK) of feed 100 lb/hr. which dissolves

acetone but is nearly immiscible with water. The method used is NRTI. The pressure

and temperature of flash 1 are 50psi and 100F respectively. Draw the Aspen flowsheet

as below :

MIXER1FLASH1

FEED

MIBK1

PRODUCT1

WA1

MA1

VAPOROD

a) Report the mass flow of MA1 and WA1.

b) WA1 is mixed using a mixer with new feed of MIBK (MIBK2) of 100 lbs/hr (100 F and50 psi) and the product is flash distillated using flash 3 ( 100F and 50 psi )to produce

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Vaprod2, WA2, MA2. Find the diffusivity coefficient of MA2 and WA2. (HINT: Select

TXPORT and make sure it is liquid phase in prop-sets-TXPORT)

c) What flowrate of new MIBK (MIBK2) is necessary to achieve 93% purity of the water

stream? (Set the target spec upper limits to 400 lbs/hr with the tolerance level to 0.001)

d) Now, MA1 and MA2 are mixed using a mixer and distillated using rad frac to produce

the final product of freewater, acetone and MIBK. Report the stream table and the mass

fraction of freewater, acetone and MIBK. The reflux ratio is 1.5 with the distillate

federate of 0.99. Take the number of stages to be 10 with vapor-liquid-freewater as the

valid phases. Assume the calculation type to be equilibrium.