Veer Narmad South Gujarat University 2010 B.E Process Calculation - 2 ( Sem3 )( Chemical ) - Question Paper
RN-8043
B. E. - II (Sem. Ill) (Chemical) Examination May/June - 2010 Process Calculation
[Total Marks : 100
Time : 3 Hours]
Instructions :
(1)
"N Seat No.
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Fillup strictly the details of signs on your answer book.
Name of the Examination :
B. E. - 2 (Sem. 3) (Chemical)
Name of the Subject:
Process Calculation
1&2
|
-Subject Code No. |
|
-Section No. (1,2,.....) |
(2) Attempt all questions.
(3) Assume suitable data necessary.
(4) Figure to the right indicates full marks.
(5) Atomic weight N = 14, H = 1, C = 12, O = 16, Cl = 35.5 Mg = 24.
(6) Use the separate answer-sheet for each section.
(a) Answer following questions : 8
(i) Find nitrogent (N) content of urea sample 2 containing 96.43% urea.
(ii) Define selectivity. 1
+ 3H2 > 2NH3
Calculate molal flowrate of hydrogen corresponding to nitrogen feed rate of 25 kmol/h if they are fed in stoichiometric proportion.
(vi) Define yield. 1
(b) In the production of formaldehyde, methanol is fed 12 to a steam heated horizontal vaporizer, which produces vapours at 358 K (85C) and 0.123 MPa g. Air is introduced with the help of blower. Compressed air is heated to 343 K(70C) and mixed in a controlled ratio with methanol vapours. The mixture contains approximately one volume of air for each volume of methanol vapours. Mixed gas is passed into the reactor and hot product gases from the reactor are cooled and scrubbed in a scrubber. Gases free from methanol and formaldehyde have following molar composition :
C02 = 4.8%, CO = 0.3%, CH4 = 0.3%, 02 = 0.3%,
H2 = 20.2% and N2 = 74.2%
The major reactions taking place in the reactor are : CH3OH HCHO + H2 HCHO -> CO + H2
CH3OH + \02 C02
CH3OH CH4 + \02 Calculate :
(a) The % conversion of methanol
(b) Yield of formaldehyde.
2 Attempt any two : 8x2=16
(i) (a) The diameter and height of a vertical cylindrical
tank are 5 ft and 6 ft 6 in respectively. It is full up to 75% height with carbon tetrachloride (CCI4) the density of which is 1.6 kg/1. Find mass in kilograms.
(b) Glycerin, weighing 600 mg is dissolved in pure water to make a final solution of 1 litre. Find the TOC and Thod of the solution.
(ii) An aqeous solution of monoethanolamine contains 20%
ME A (by weight). It is utilized for the absorption of C02. Rich solution from the absorber contains 40 volumes C02. Calculate C02 loading in terms of moles C02 dissolved per mole ME A assuming that density of the solution is 1.011 kg/1.
(iii) Nitrogen hydrogen mixture with a molar ratio of 1:3 is used for the manufacture of NH3. Where 18% conversion is achieved. After separating NH3 from product the unconverted gases are recycled. The feed contains 0.2 mole of argon per 100 moles of N2-H2 mixture. The toleration limit of argon entering the reactor is 6 parts to 100 parts of N2-H2 mixture by volume. Calculate :
(a) The fraction of recycle that must be continually purged.
(b) The overall yield of ammonia.
3 Attempt any two : 7x2=14
(i) The analysis of a sample of Babul bark yields 5.8% moisture, 12.6% tannin, 8.3% soluble non-tannin organic matter and the rest lignin. In order to extract tannin out of the bark, a counter current extraction process is employed. The residue from the extraction process is analysed and found to contain 0.92% tannin and
0.65% soluble non-tannin organic matter on a dry basis.
Find the percentage of tannin recovered on the basis of original tannin present in the bark. All analysis are given on weight basis.
(ii) Limestone is a mixture of calcium and magnesium carbonates and inert material. Lime is made by calcining the carbonates i.e. heating them until C02 is driven off by the reactions :
CaC03 CaO + C02
MgC03 MgO + C02
When 100 kg of limestone is calcined, 44 kg of C02 is obtained. If the limestone contains 10% inerts, calculate the complete analysis.
|
Ethylene |
30.6% |
|
Benzene |
24.5% |
|
Oxygen |
1.3% |
|
Methane |
15.5% |
|
Ethane |
25.0% |
|
Nitrogen |
3.1% |
Find :
(a) The average molecular weight of gas mixture
(b) The composition by weight
(c) The density of mixture in kg/m3 at NTP.
4 (a) Answer the following questions briefly : 4x1=4
(i) Define calorific values - GHV and NHV of fuel.
(ii) Write the Watson equation used in computing the latent heat of vaporization.
(iii) Enumerate the applications of Hess's law.
(iv) What is recycle ratio?
(i) Explain the proximate analysis of coal.
(ii) The gross calorific value of gaseous propane is 2219.71 kJ/mol at 298 K. Calculate its net calorific value if the latent heat of vaporization of water is 2442.5 kJ/kg at this temperature.
(c) Solve the followings : 2x5=10
(i) Temperature of 1 mole of pure oxygen is raised from 350 K to 1500 K. Calculate the heat required
o
using Cp data.
Cp = a + bT + cT2 + dT3 kJ/(k mol K)
Where a = 26.0257
b = 11.7551 x 103
c = -2.3426 x 106
d = -0.5623 x lO-9 RN-8043] 4 [Contd...
(ii) Calculate the latent heat of vaporization of o-xylene at its normal boiling point using Riedel equation. Normal boiling point of o-xylene is
417.5 K. The critical temperature and critical pressure of o-xylene are 630.3 K and 3730 kPa.
5 Attempt any two : 2x8=16
(i) A fuel gas has the following composition by volume :
|
Species |
% by volume |
|
C2 5H4 2 (illuminants) |
7.0 |
|
Cj 2H4 4 (paraffins) |
11.2 |
|
O O |
2.1 |
|
CO |
33.8 |
|
H2 |
40.6 |
|
02 |
0.5 |
|
n2 |
4.8 |
(a) Calculate the theoretical number of moles of oxygen for the combustion of 1 mole of the gas.
(b) Calculate % molar composition of the flue gases formed by burning the fuel gas with 30% excess air. Assume all the combustile components are burnt to C02 and H20.
(ii) Monochloroacetic acid (MCA) is manufactured in a Semibatch reactor by the action of glacial acetic acid with chlorine gas at 373 K. MCA thus formed will further react with chlorine to form dichloroacetic acid (DCA). To prevent the formation of DCA, excess acetic acid is used. A small-scaled unit which produces 5000 kg/day MCA requires 4536 kg/day of chlorine gas. Also, 263 kg/day of DCA is separated in the crystallizer to get almost pure MCA product.
Find :
(a) % conversion
(b) % yield of MCA and
(c) Selectivity.
CHgCOOH + Cl2 CH2ClCOOH + HC1
(MCA)
CH2 Cl COOH + Cl2 CHC12 COOH + HC1
(DC A)
(iii) A coal with the following specifications is burnt with 100% excess air :
|
Constituents of coal |
% by weight |
|
C |
50.22 |
|
H |
2.79 |
|
S |
0.37 |
|
N |
2.05 |
|
O |
18.04 |
|
Moisture |
7.0 |
Calculate (a) The theoretical requirement of 02 per kg of the coal (b) Flue gas analysis.
(ii) Liquid Benzene at 303 K is mixed and dissolved continuously with liquid toluene which is at 373 K in the molar ratio 3:2 (Benzene: toluene) in an insulated tank. If the heat of mixing is assumed to be zero, what is the temperature of the mixed solution? Molecular weights of benzene and toluene are 78 kg/kmol and 92 kg/kmol respectively. The heat capacity Cp of these liquids follows :
Cp = a + bt where T is absolute temperature.
Data :
|
T(K) |
Cp of Benzene kJ/kg-K |
Cp of Toluene kJ/kg-K |
|
283 |
1.591 |
1.524 |
|
338 |
2.018 | |
|
358 |
2.236 |
(iii) Evaluate heat of reaction for S02 + 02 S03 occurring at 1 atm. pressure and 775 K. The
heat capacity follows Cp = a+ bT + cT2 + dT3 in
kJ/(kmol K). Heat of reaction at 298.15 K is -98910 kJ/kmol of S02 used up.
|
Species |
a |
b x 103 |
d x 109 | |
|
S02 |
24.771 |
62.9481 |
-44.2582 |
11.122 |
|
02 |
26.0257 |
11.7551 |
-2.3426 |
-0.5623 |
|
so3 |
22.0376 |
121.624 |
-91.8673 |
24.3691 |
RN-8043] 7 [ 200 ]
Attempt any two : 2x7=14
(i) In a water cooling tower, air enters at height of 1 mt above the ground level and leaves at the height of
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Attachment: |
| Earning: Approval pending. |
