G U JARA T T EC H N OLO G ICA L U N IV E R S...

GUJARAT TECHNOLOGICAL UNIVERSITY

CHEMICAL ENGINEERING

PROCESS CALCULATION

SUBJECT CODE: 2130504

B.E. Semester: III

Type of course: Fundamental Chemical Engineering Calculations & stoichiometry

Prerequisite: None

Rationale: The prime objective of this subject is to clear fundamentals of chemical engineering in a

simple and forthright manner and to provide the broad background for applying these principles to

industrial and theoretical problems.

After learning the course the students should be able:

To understand the importance of stoichiometry – material and energy balances

To deal with the laws of conservation of mass and energy

To apply principles of unit operations and chemical reaction engineering in problem solving

Teaching and Examination Scheme:

Teaching Scheme Credits Examination Marks Total

Marks L T P C Theory Marks Practical Marks

ESE

(E)

PA (M) PA (V) PA

(I) PA ALA ESE OEP

3 1 0 4 70 20 10 30 0 20 150

Course Contents:

Sr.

No.

Topic

Teaching

Hrs.

Module

Weightage

1 Dimensions and units:

Dimensions and system of units, Fundamental and derived units,

Dimensional consistency, Dimensional equations, Different ways of

expressing units of quantities and physical constant, Unit conversion and its

significance

5 9

2 Basic chemical calculations:

Calculations for mole, molecular weight, equivalent weight, etc.,

Composition of gaseous mixtures, liquid mixtures, solid mixtures, etc.,

Ideal gas law & other equations of state and their applications, Dalton law,

Raoult’s law, Henry’s law, Solutions and their properties

7 13

3 Material balance without chemical reactions:

Process flowsheet, Degree of freedom, Material balance with and without

recycle; Bypass and purge streams, Material balance around equipments

related to unit operations like absorber and stripper, distillation towers,

extractors, dryers, evaporators, etc. Material balance of unsteady state

operations.

8 15

4 Material balance involving chemical reactions:

Concept of limiting and excess reactants, percentage conversion, yield,

selectivity, etc., M aterial balance with chemical reactions - single and

multiple reactions, Material balance involving reactions with special

reference to fertilizers, petrochemicals, dyestuffs, electrochemical

industries, metallurgical industries, etc.

10 18

5 Energy balances:

Thermochemistry and 1st law of thermodynamics, Heat capacity of gases

9 17

and gaseous mixtures, liquids & solids, Sensible heat change in liquids &

gases, Enthalpy changes during phase transformation, Enthalpy changes

accompanied by chemical reactions, Standard heat of reaction, Adiabatic

reactions, Thermo-chemistry of mixing processes, Dissolution of solids,

etc.

6 Stoichiometry and Unit operations:

Distillation, Absorption and stripping, Extraction & leaching,

Crystallization, Psychrometric Operations, Drying, Evaporation etc.

7 13

7 Fuels and combustion:

Types of fuels, Calorific value of fuels, Problems on combustion of coal,

liquid fuels, gaseous fuels, etc., Proximate and ultimate analysis,

Combustion calculations, theoretical flame temperature, etc., Air

requirement and flue gases.

8 15

Reference Books:

1. “Stoichiometry”, B.I. Bhatt, S.M. Vora, McGraw Hill Publishing Company Limited, 4th edition,

2004.

2. “Basic Principles & Calculations in Chemical Engineering”, David M. Himmelblau, James B.

Riggs, PHI Learing Pvt. Ltd, 7th edition, 2006.

3. “Elementary Principles of Chemical Processes”, Richard M. Felder, Ronald W. Rousseau, Wiley,

3rd

edition, 2004.

4. “Chemical Process Principles Part-I: Material and Energy Balances”, O.A.Hougen, K.M.Watson,

R.A.Ragatz, CBS Publishers New Delhi, 2nd

edition, 2004.

5. “Stoichiometry and Process Calculations”, K.V. Narayanan, B. Lakshmikutty, Prentice-Hall of

India Pvt. Ltd., 2006.

6. “Industrial Stoichiometry: Chemical Calculations of Manufacturing Processes”, H.C.Lewis,

W.K.Lewis, A.H.Radasch, McGraw-Hill, 2nd

edition, 1954.

Course Outcome:

After learning the course, the students should be able to:

Establish mathematical methodologies for the computation of material balances and energy

balances

Present an overview of industrial chemical processes.

Develop a fundamental understanding of the basic principles of chemical engineering processes

and calculations.

Examine and select pertinent data, and solve material and energy balance problems.

Give examples of important application of material balances in chemical engineering processes.

Evaluate their own solutions and those of others to find and correct errors.

List of Open Source Software/learning website:

Students can refer to video lectures available on the websites including NPTEL.

Students can refer to the CDs which are available with some reference books for the solution of

problems using softwares/spreadsheets. Students can develop their own programs/ spreadsheets for

the solutions of problems.

ACTIVE LEARNING ASSIGNMENTS: Preparation of power-point slides, which include videos,

animations, pictures, graphics for better understanding theory and practical work – The faculty will

allocate chapters/ parts of chapters to groups of students so that the entire syllabus to be covered. The

power-point slides should be put up on the web-site of the College/ Institute, along with the names of the

students of the group, the name of the faculty, Department and College on the first slide. The best three

works should submit to GTU.

1

Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III (NEW) - EXAMINATION – SUMMER 2017

Subject Code: 2130504 Date: 02/06/2017 Subject Name: Process Calculation Time: 10:30 AM to 01:30 PM Total Marks: 70

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks. 4. Atomic Weights: C= 12, H=1, O= 16, S= 32, Na= 23, K= 39, Cl= 35.5, N= 14

MARKS

Q.1 Short Questions 14

1 The value of gas constant ‘R’ is ________ m3 atm/kmol K

2 At NTP, 1 atm = _____ mH2O

3 Define: Normality and Molarity.

4 A sample of water contains 2000 ppm solids. Express the concentration of

solids in the sample in weight percent.

5 Draw and explain with block diagram, distillation operation for a binary

system.

6 Define “Tie” and “Inert” material with example.

7 If cooling tower water available at 298 K is used at a rate of 1500 kg/h for

heat duty of 119647.78 kJ/h, calculate the outlet temperature of water

assuming specific heat of water to be 4.187 kJ/kg K.

8 Calculate the quantity of ethylene required for the production of 100 kg

ethylene oxide.

9 What is the composition of 100 kg 20 % oleum ?

10 In the production of sulphur trioxide, 100 kmol of SO2 and 200 kmol of O2 are

fed to a reactor. The product stream is found to contain 80 kmol of SO3. Find

the percentage conversion of SO2.

11 Define: Latent heat of vaporization and latent heat of sublimation

12 State Hess’s Law of constant heat summation

13 Convert: Wavelength 9000Ao to nm

14 Iron metal weighing 500 lb occupies a volume of 29.25 L. Calculate the

density of Fe in kg/dm3.

Q.2 (a) Explain Ideal gas law, Dalton’s law and Raoult’s law. 03

(b) A sample of caustic flakes contains 74.6% Na2O by weight. Determine the

purity of flakes. 04

(c) Carbon dioxide is dissolved to the extent of 38 litres per litre of solution

containing 27.5 wt. % A [mol. wt.= 79]. The volume of gas is measured at

101.325 kPa at 288 K. Calculate the weight % and mole % CO2 in the

solution. Density of the solution is 1.04 kg/L.

07

OR

(c) An aqueous solution of K2CO3 is prepared by dissolving 43 kg of K2CO3 in

100 kg of water at 293 K. Calculate the normality, molarity and molatity of

the solution. Density of the solution is 1.3 kg/l.

07

Q.3 (a) In a textile mill, a double effect evaporator system concentrates weak liquor 03

C2H4 + ½ O2 C2H4O

2

containing 4% (by mass) caustic soda to produce lye containing 25% solids

(by mass). Calculate the evaporation of water per 100 kg feed in the

evaporator.

(b) Explain recycle, bypass and purge streams with suitable diagram. 04

(c) Pure sulphur is burnt in a sulphur burner using dry air. Oxygen is used 20%

excess above that required for the complete combustion of sulphur to SO3.

The burner efficiency is such that only 30% of the sulphur burns to SO3 and

the remainder burns to SO2. Calculate: (a) the analysis of the resulting mixture

in mole% and (b) the weight of the gas produced per kg of sulphur burnt.

07

OR

Q.3 (a) Define: (a) Yield (b) Conversion (c) Limiting and excess reactant 03

(b) 100 kg mixture of 27.8% of acetone (A) and 72.2% of chloroform (B) by mass

is to be batch-extracted with a mixed solvent at 25° C. The mixed solvent of

an unknown composition is known to contain water (S1) and acetic acid (S2).

The mixture of the original mixture and the mixed solvent is shaken well,

allowed to attain equilibrium, and separated into two layers. The compositions

of the two layers are given below. Find the quantities of the two layers.

Composition, mass%

Layer A B S1 S2

Upper Layer 7.5 3.5 57.4 31.6

Lower Layer 20.3 67.3 2.8 9.6

04

(c) It is required to make 1000 kg of mixed acid containing 60% H2SO4, 32%

HNO3 and 8% water by blending (i) the spent acid containing 11.3% HNO3,

44.4% H2SO4 and 44.3% H2O, (ii) aqueous 90% HNO3, and (iii) aqueous 98%

H2SO4. All percentages are by mass. Calculate the quantities of each of the

three acids required for blending.

07

Q.4 (a) Explain: (i) Watson equation and (ii) Riedel Equation. 03

(b) Define the following terms with reference to air-water humidification

operation:

(1) Dry-bulb temperature

(2) Absolute humidity

(3) Humid heat

(4) Dew point

04

(c) Formaldehyde is produced by dehydrogenation of methanol.

The per pass conversion is 67%. The product leaving the reactor is fed to a

separation unit battery where formaldehyde is separated from methanol and

hydrogen. The separated methanol is recycled to the reactor. If the production

rate of formaldehyde is 1000 kg/h, calculate: (a) the combined feed ratio and

(b) the flow rate of methanol required to the process (as fresh feed). As shown

in the figure, the following operation is taking place in the dehydrogenation

plant.

07

OR

CH3OH HCHO +

H2

Methanol

(R)

Methanol (F) M

H

2

Separati

on

Units

Reacto

r

Formaldeh

yde

3

*************

Q.4 (a) Define and explain the following terms:

(1) Heat of formation

(2) Heat of combustion

(3) Heat of reaction

03

(b) Differentiate between: (i) Sensible Heat and latent heat (ii) Endothermic and

exothermic reactions. 04

(c) Calculate the consumption of 96% NaCl and 93% H2SO4 to produce 500 kg of

HCl if the conversion is 92%. The reaction that takes place is as follows:

07

Q.5 (a) In a double effect evaporator plant, the second effect is maintained under

vacuum of 475 Torr. Find the absolute pressure in kPa, bar and psi. 03

(b) Crude oil is found to contain 87.1% carbon, 12.5% hydrogen and 0.4%

sulphur (by mass). Its GCV at 25oC is measured to be 45071 kJ/kg oil.

Calculate its NCV at 25oC. Latent heat of water vapor at 25oC = 2442.5 kJ/kg

04

(c) A mixture of aniline and water containing 11.8% by weight of aniline is

cooled from 100 oC to 40 oC with the help of cooling water. Find the amount

of heat removed by cooling 100 kg of aniline mixture. The specific Cp= a +

bT + cT2 (kcal/kg oC)

Where constants a, b, c are:

For aniline: a= 1.407, b= 2.467 X 10-3, c= -6.08 X 10-6

For water: a= 0.6741, b= 2.8 X 10-3, c= 8.3 X 10-6

07

OR

Q.5 (a) A stream of carbon dioxide flowing at a rate of 100 kmol/min is heated from

298 K to 383 K. Calculate the heat that must be transferred using Cop.

Data:

Cop= a + bT + cT2 + dT3 , kJ/(kmol. K)

Gas a b X 103 c X 106 d X 109

Liquid 21.3655 64.2841 -41.0506 9.7999

03

(b) Discuss proximate and ultimate analysis of coal. 04

(c) The orsat analysis of the flue gases by mole is as given below: CO2- 11.4%,

O2- 4.2% and N2- 84.4%. Assuming that complete combustion takes place.

Calculate (i) the % excess air (2) find the C:H ratio in the fuel.

07

2 NaCl + H2SO4 Na2SO4 + 2

HCl

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III(New) • EXAMINATION – WINTER 2016

Subject Code:2130504 Date:04/01/2017

Subject Name:Process Calculation

Time: 10:30 AM to 01:30 PM Total Marks: 70 Instructions:



3. Figures to the right indicate full marks.

4. Mol. Wt: C=12, O=16, N=14, H=1, Na=23, K=38, Cl=35.5, S=32,

Q.1 Answer the following:

(i) The SI unit of pressure is _____________.

(ii) Density is a fundamental quantity. (True/False).

(iii) 1 atm = ___________ bar.

(iv) Unit of Luminous intensity is ___________.

(v) Number of mol of solute dissolved in 1 kg of solvent is known as ____.

(vi) Chlorine and Oxygen are monoatomic elements. (True/False).

(vii) What is the use of pH measurement?

(viii) Name equation of states for non-ideal gases.

(ix) Define limiting reactant.

x) The heat capacity of 1 kg of dry air and the moisture comtained in it is

known as _________

xi) Define relative humidity.

xii) Name the parameters determined in proximate analysis of coal.

xiii) Which is better for combustion process, gaseous fuel or liquid fuel?

xiv) External agent added to separate liquid mixtures by extraction process

is known as ______________.

14

Q.2 (a) A mixture of NaOH ( M = 40.0 g/mol ) and KOH ( M = 56 g/mol ) contains

60 % of KOH. Calculate the content of both components in the mixture in

mol %.

03

(b) Explain (i) Boyle’s law, (ii) Dalton’s law. 04

(c) 750m3 of air of 400C and 740mm Hg is flowing through a pipeline.

Calculate the molar flow rate and mass flow rate. What are the partial

pressures of O2 and N2?

07

OR

(c) Describe the different methods to solve material balance problem with

examples. 07

Q.3 (a) Metallic Aluminium weighs 100lb and occupies a volume of 16.8 L. Find

the density of Aluminium in kg/m3. 03

(b) Aqueous solution of triethanolmine (TEA) of molar mass 149 contains 50%

TEA by mass. Find the molarity of the solution if the density of the solution

is 1.05 kg/L.

04

(c) A coal containing 85% Carbon, & 8% H2 and remaining ash is burnt in a

furnace with 30% excess air. Assume complete combustion. Calculate:

(i) the quantity of air supplied per kg of coal burnt.

(ii) the composition of flue gases in wt%.

07

OR

Q.3 (a) A salt solution is to be made containing 65% by weight of salt. The two

solutions available contain 48% by weight of salt and 73% by weight of salt. 03

2

In what proportion these streams are to be mixed to get te desired solution.

(b) Answer in brief:

(i) Differentiate between fundamental quantity and derived quantity.

(ii) What is Joule-Thompson effect in gas throttling?

04

(c) Pure methane is completely burned with air in a combustor. The outlet gas

from the combustor is passed through a cooler where some of the moisture

is removed. The gas leaving the cooler contains 0.8335 mol. fraction of

Nitrogen. The combustion reaction taking place is:

CH4 + 2O2 CO2 + 2 H2O. Calculate:

(i) analysis of gas leaving the cooler

(ii) weight of water condensed per mole of methane burnt.

07

Q.4 (a) Write a short note on classification of fuels. 03


(i) Define GCV and NCV.

(ii) How to decide the quantity of excess air for combustion process?

04

(c) Vapor phase oxidation of ethyl alcohol using Copper catalyst at 5500C

produces acetaldehyde by the following reaction:

C2H5OH + 0.5 O2 CH3CHO + H2O.

The conversion is 30% and excess air supplied is 10%. Calculate the

composition of product stream if 100kg of C2H5OH per hour is fed to the

reactor.

07

OR

Q.4 (a) Explain ultimate analysis of coal. 03


(i) Differentiate between sensible heat and latent heat.

(ii) Define yield and conversion.

04

(c) Pure methane is heated from 303K to 523K at atmospheric pressure.

Calculate the heat added per kmole methane using CP data.

CP = a + bT + cT2 + dT3 . Data for methane:

a = 19.2494, b × 103 = 52.1135, c × 106 = 11.973, d × 109 = -11.3173

07

Q.5 (a) Explain extraction process. 03

(b) 100 kg of Cadmium at 270C is to be melted. The heat is supplied by steam.

Calculate mass of steam to be supplied.

Data:

Melting Point of Cadmium is 320.9 0C.

At. wt of Cadmium = 112.

Use Cp = 6 + 0.005T kcal/kmol0C where T is in 0C.

Latent heat of fusion = 2050 kcal/kmol.

Latent heat of steam = 210 kcal/kg

04

(c) 15000 kg/day of a mixture containing methyl ethyl ketone (MEK) and

butanol is to be separated into top product containing 99.5 mole% MEK.

The bottom product should not contain more than 1% of MEK. Feed

mixture contains 68 mole % of MEK. If 475 kmoles of vapor/day are

leaving the column, calculate: (i) top and bottom product obtained per day,(

ii) reflux ratio.

Data: Mol. Wt. of MEK = 72 and butanol = 74.

07

OR

Q.5 (a) Explain the significance of a Psychrometric chart. 03

(b) Show the material balance of a distillation column with a neat sketch. 04

(c) A multiple contact counter current extractor is employed to extract oil from

halibut livers with the help of ethyl ether. The fresh livers are charged to the 07

3

extractor at the rate of 1000 kg.h and contains 25.7% oil. Pure ether enters

the bottom of the extractor. The overflow from the extractor contains 70%

oil. The underflow rate is 0.23 kg solution/kg oil-free solids and is known to

contain 12.8% oil. All % are by mass. Determine:

(i) the percentage recovery of oil.

(ii) the flow rate of ether to the extractor.

*************

1



BE - SEMESTER–III(New) EXAMINATION – SUMMER 2016


Subject Name:Process Calculation Time:10:30 AM to 01:30 PM Total Marks: 70 Instructions:


2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks.

Q.1 Answer the following questions: 14

1 Write down four different units of pressure.

2 Define Dalton’s law.

3 Define mole.

4 Define degree of freedom.

5 What is Cox chart?

6 Define vapor pressure.

7 Define limiting reactant.

8 Define selectivity.

9 Define heat of reaction.

10 What is difference between sensible heat and latent heat?

11 If pipe diameter is increased at the same place in pipe line, what will happen to

kinetic energy per unit mass of incompressible fluid flowing through pipe?

12 Define excess reactant.

13 Define calorific value of fuel.

14 Define orsat analysis of flue gas.

Q.2 (a) An orifice meter is used to measure the flow rate in pipes. The flow rate is related to the

pressure drop by an equation of the form,

Pu C

Where, u = fluid velocity in m/s, P =Pressure drop in N/m2, =density of flowing

fluid in kg/m3, C is proportionality constant. What is the unit of C in the SI system of

units?

03

(b) What is the specific gravity of propane at 310.77K and 800 mmHg relative to air

at 288.55K and 760 mmHg?

04

(c) A natural gas has the following mole percent composition,

CH4 = 87%, C2H6 = 12% and C3H8 = 1%.

(1) What is the composition in weight percent?

(2) How many m3 will be occupied by 80 kg of gas at 9C and 600 kPa?

07

OR

(c) Vapour pressure benzene in the temperature range of 7.5 C to 104 C can be

calculated using the following Antoine equation.

10

1211log 6.9057

220.8P

t

Where, P = Vapour pressure in torr

t = Temperature in C

Convert the above equation in SI units.

07

2

Q.3 (a) Define Raoult’s law. What are the applications and limitations of Raoult’s law?

03

(b) A sugar solution contains 5.2% sugar by weight in water. How many kg of 1.2% solution

is required to dilute 100 kg of 5.2% solution to 4.2%?

04

(c) A distillation column separates 10000 kg/hr of a 50% benzene-50% toluene mixture. The

product D recovered from the condenser at the top of the column contains 95% benzene,

and the bottom W from the column contains 96% toluene. The vapor stream V entering

the condenser from the top of the column is 8000 kg/hr. A portion of the product from the

condenser is returned to the column as reflux, and the rest is withdrawn for use

elsewhere. Assumes that the compositions of the streams at the top of the column (V), the

product withdrawn (D), and the reflux (R) are identical because the V stream is

condensed completely. Find the ratio of the amount refluxed (R) to the product

withdrawn (D).

07

OR

Q.3 (a) Describe the reasons for performing bypassing and recycling operations in unit

operations. 03

(b) Tallow is essential glyceryl tristearate. It is desired to seponify the tallow with

caustic soda. For 100 kg of tallow, calculate (a) the theoretical requirement of

caustic soda, and (b) the amount of glycerin liberated.

Data Given: Molecular weight of glyceryl tristearate = 890 kg/kgmol

Molecular weight of caustic soda = 40 kg/kgmol

Molecular weight of sodium stearate = 306 kg/kgmol

Molecular weight of glycerin = 92 kg/kgmol

04

(c) Immobilized glucose isomerase is used as a catalyst in producing fructose from glucose

in a fixed-bed reactor (water is the solvent). For the system shown in the Figure 1, what

percent conversion of glucose results on one pass through the reactor when the ratio of

the exit stream to the recycle stream in mass units is equal to 8.33 ?

07

Q.4 (a) Describe proximate analysis of coal. 03

(b) Calculate the enthalpy change in 24 gm of N2 if heated from 300 K to 1500 K at

constant pressure.

Data given: Heat capacity equation 0 2 3

PC a bT CT dT in J/(mol K)

For N2 a b c d

29 0.2199 x 10-2 0.5723 x 10-5 -2.871 x 10-9

04

(c) Define yield and conversion.

Monochloroacetic acid (MCA) is manufactured in a semibatch reactor by the

action of glacial acetic acid with chlorine gas at 100 C in the presence of PCl3

catalyst. 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 scale unit

which produces 5000 kg/day MCA, requires 4536 kg/day of chlorine gas. Also, 263

kg/day of DCA is separated into crystallizer to get almost pure MCA product. Find the

%conversion, %yield of MCA.

07

OR

Recycle

Fixed-Bed

Reactor

Feed

40%

Glucose

in water

4%

Fructose

Product

Figure 1

3

Q.4 (a) Calculate the standard heat of reaction for the following reaction:

3( ) 2( ) ( ) 2 ( )4 5 4 6g g g gNH O NO H O

Data given:

Species 3( )gNH 2( )gO ( )gNO 2 ( )gH O

0ˆ ( / )fH kJ mol at 25 C and 1 atm -46.191 0 90.374 -241.826

03

(b) For o-xylene, calculate (a) latent heatof vaporization at TB using Riedel equation,

and (b) latent heat of vaporization at 25 C using Watson equation.

Data given:

For o-xylene: Pc = 3732 kPa, Tc = 630.3 K, TB = 417.6 K

04

(c) Answer the following questions.

i. Briefly describe the term adiabatic reaction temperature.

ii. Describe Pressure-Enthalpy chart for any pure component. What is the

value of latent heat of vaporization at critical point? Why?

03

04

Q.5 (a) If 10 kg of C7H16 reacts completely with stoichiometric quantity of O2, how many kg of

CO2 will be found as product?

03

(b) If 3.2 moles of A, 1.1 moles of B & 2.4 moles of C are fed as reactant in the reactor,

which will be limiting reactant. Following reaction takes place in the reactor:

3 2 PrA B C oduct

04

(c) A multiple contact counter current extractor is employed to extract oil from

halibut livers with the help of ethyl ether. The fresh livers are charged to the

extractor at the rate of 1000 kg/h and contain 25.7 % oil (by mass). Pure ether

enters the bottom of the extractor. The overflow from the extractor contains 70%

oil (by mass). The underflow rate is 0.23 kg solution/kg of oil-free solids and is

known to contain 12.8% oil (by mass). Based on these operating conditions, make

the material balance and find the flow rate of ether to the extractor. Also, compute

the percentage recovery of oil.

07

OR

Q.5 (a) Crude of is found to contain 87.1% carbon, 12.5 % hydrogen and 0.4 % sulphur

(by mass). Its gross calorific value at 25 C is measured to be 45071 kJ/kg oil.

Calculate its net calorific value at 25 C.

Data given: Latent heat of water vapor at 25 C = 2442.5 kJ/kg

03

(b) Describe the classification of fuels.

04

(c) Compressed propane has been suggested as a source of economic power for

vehicles. Suppose that in a test 20 kg of C3H8 is burned with 400 kg of air to

produce 44 kg of CO2 and 12 kg of CO. What was the % excess air?

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III (New) EXAMINATION – WINTER 2015


Subject Name: PROCESS CALCULATION

Time: 02.30pm to 05:00pm Total Marks: 70 Instructions:




4. Consider Atomic weight : Si=28, Al=26.98, Mn=54.93, Bo=10.81, Zn=65.39

MARKS

Q.1 Short Questions 14

1 What is Ideal Gas Law?

2 1Atmospheric pressure = ----------- Psi.

3 Write down different forms of conversion of temperature.

4 What is mass flow rate?

5 What is Steady state process?

6 Define: Molarity.

7 Define: Molality.

8 Define: Normality.

9 Define: Conversion.

10 Define: Yield.

11 Define: Specific gravity of a gas

12 State that Roult’s law

‘

‘s

13 Find the molecular weight of KMnO4.

14 What is the equivalent weight of Al2 (SO4)3?

Q.2 (a) Vapour pressure of benzene in the temperature range of

280.65 K (7.5o C) to377.15 K (104oC) can be calculated.

By using the following Antoine equation.

log 10 p = 6.9057 – 1211.0

t + 220.8

Where, p=vapour pressure in torr (mm Hg) & t=temperature

in °C convert the above equation in SI Units.

03

(b) The diameter and height of a vertical cylindrical tank are

5ft and 6ft 6 inch respectively. It is full up to 75% height

with carbon tetrachloride, the density of which is 1.6

kg/litre. Find the mass in kilograms.

04

(c) In a double effect evaporator plant the second effect is

maintain under vacuum of 475 torr (mmHg).Find the

absolute pressure in Kgf/cm2, Kpa, atm, N/m2, bar.Psi,

and mmHg.

07

OR

(c) The analysis of a sample of glass yields 7.8%Na2O,

7.0%MgO, 9.7%ZnO, 2.0%Al2O3, 8.5%B2O3 and

65%SiO2 (by weight).Convert this composition into

mole%.

07

Q.3 (a) Iron metal weighing 500 lb occupies a volume of 29.25

litres. Calculate the density of Fe in gm/cm3. 03

(b) Using Watson equation, calculate latent heat of 04

2

vaporization of acetone at 313 K.

Data: Latent heat of acetone at 329.4 K = 29121 kJ/kmol

Critical temperature of acetone = 508.1 K.

(c) Cracked gas from a petroleum refinery has the following

composition by volume methane 45%, Ethane10%,

ethylene 25%, Propane 7%, Propylene 8%, n-Butane 5%

.Find (a) Average mol.wt.of gas mixture. (b)the

composition by weight and (c) Specific gravity of the gas

mixture.

07

OR

Q.3 (a) Explain standard heat of reaction and standard heat of

combustion. 03

(b) Discuss methods of solving material balance problems

without chemical reaction. 04

(c) It is required to make 1000 kg mixed acid containing

60%H2SO4,32%HNO3and 8%water by blending (i) the

spent acid containing 11.3% HNO3,44.4% H2SO4and

44.3%H2O (ii) aqueous 90% HNO3, and (iii) aqueous

98% H2SO4.All percentages are by weight. Calculate the

quantities of each of the three acids required for blending.

07

Q.4 (a) In a textile mill, a double-effect evaporator system

concentrates weak liquor containing 4 %( by weight)

caustic soda to produce a lye containing 25% solids (by

weight).Calculate the evaporation of water per 100kg

feed in the evaporator.

03

(b) Discuss uses of recycling and bypassing operation 04

(c) Soya bean seeds are extracted with hexane in batch

reactors. The flacked seeds Contains18.6% oil,

69.0%solids and12.4% moisture. At the end of the

extraction process cake is separated from the hexane oil

mixture. The cake analysis yields 0.8%oil, 87.7%solids

and 11.5% moisture. Find the percentage recovery of oil.

All percentage is on wt.basis.

07

OR

Q.4 (a) Pure methane is heated from 303 K to 523 K at

atmospheric pressure. Calculate the heat added per kmol

methane using the following data:

Cp = 19.2494 + 52.1135 x 10-3T + 11.973 x 10-6 T2

– 11.3173 x 10-9 T3 KJ/(Kmol-K)

03

(b) Using Antoine equation calculate the vapour pressure of acetic

acid at 316 K.

Data: A=6.5127 B= 1533.30 C= -50.8500

04

(c) What will be the yield of Glauber salt (Na2SO4.10H2O) if

a pure 32%solution is cooled to 293K (20oC) without any

loss due to evaporation? Data: Solubility of Na2SO4 in

water at 293K (20oC) is 19.4kgper 100kg water.

07

Q.5 (a) Define the term with reference to air-water

humidification operation :

(a) Dry-Bulb Temperature (b) Absolute Humidity

(c) Percentage Humidity

03

(b) Define the term with reference to air-water

humidification operation : (a) Relative Humidity (b)

Dew- Point (c) Humid Heat (d) Humid Volume

04

(c) The dry bulb temperature and dew point of a humid air

were found to be 302K (29oC) AND 291K (18oC) 07

3

respectively. The barometer reads 100kpa (750torr).

Compute (a) the absolute molal humidity (b) the absolute

humidity (c) the percentage RH (d) the percentage

saturation (e) the humid heat and (f) the humid volume.

OR

Q.5 (a) Define GCV and NCV for fuels. Give its importance. 03

(b) Give the names of the equipments used for measuring CV

of solid, liquid and gases. 04

(c) The Orsat analysis of the flue gases from a boiler house

chimney gives CO2: 11.4%, O2:4.2% and N2:84.4 %(

mole %).

Assuming that complete combustion has taken place,(a)

calculate the % excess air and (b) find the C:H ratio in the

fuel.

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER– III (NEW) EXAMINATION – SUMMER 2015


Subject Name: PROCESS CALCULATION

Time: 02.30pm-05.30pm Total Marks: 70 Instructions:




4. Atomic weight: C=12, H=1, N=14, S=32, Ca=40, Na=23, Cl=35.5, Mg=24, O=16

Q.1 (a) The conductance of a fluid flow system is defined as the volumetric flow rate,

referred to a pressure of one torr (133.233 Pa). For an orifice, the conductance C

can be computed from

C= 89.2 A (T/M) 1/2 ft3 / s

where, A = area of opening, ft2, T = temperature, 0R, M = Molar mass

Convert the empirical equation in SI units.

07

(b) Define: (i) limiting reactant (ii) selectivity (iii) excess reactant (iv) law of

conservation of energy (v) yield (vi) latent heat of vaporization (vii) calorific value

of fuel

07

Q.2 (a) The feed water to the reverse osmosis plant has dissolved solids to the extent of

5000 mg/L. The feed to product ratio (on mass basis) is 4:3. The treated water

(product) from the plant contains 600 mg/L of solids. Find the dissolved solids in

the reject stream.

07

(b) The analysis of a sewage gas sample from a municipal sewage treatment plant is

given below on a volume basis: Methane 68%, Carbon dioxide 30%, Ammonia

2%, and Traces of H2S, SO2, etc. Find (a) the average molar mass of the gas; and

(b) the density of the gas at NTP.

07

OR

(b) Heat capacity data for gaseous SO2 are reported in standard data book and also by

following equation C0mp = 43.458 + 10.634 × 10-3 T – 5.945 × 105/ T2 Calculate

the heat required to raise the temperature of 1 kmol pure SO2 from 300 to 1000 K,

using the above equation.

07

Q.3 (a) A sample of milliolite limestone, obtained from Porbandar, Gujarat, is found to

contain 54.5% CaO (by mass). If this CaO is present as CaCO3 in the limestone,

find the content of CaCO3 in the limestone.

07

(b) A solution of sodium chloride in water contains 20% NaCl (by mass) at 333 K.

The density of the solution is 1.127 kg/L. Find the molarity, normality and molality

of the solution.

07

OR

2

Q.3 (a) A 100 kg mixture of 27.8% of acetone (A) and 72.2% of chloroform (B) by mass

is to be batch-extracted with a mixed solvent at 298 K (250 C). The mixed solvent

of an unknown composition is known to contain water (S1) and acetic acid (S2).

The mixture of the original mixture and the mixed solvent is shaken well, allowed

to attain equilibrium, and separated into two layers. The compositions of the two

layers are given below.

Composition of immiscible Layers

Composition, mass%

Layer A B S1 S2

Upper layer 7.5 3.5 57.4 3.16

Lower layer 20.3 67.3 2.8 9.6

Find (a) the quantities of the two layers, (b) the mass- ratio of the mixed solvent to

the original mixture, and (c) the composition of the mixed solvent (mass basis).

07

(b) CO2 dissolved to the extent of 38 liter per liter of solution of 27.5% by weight DAPOL.

The volume of CO2 gas measured at 101.325 kPa and 288.7 K. Find Wt% and mole% of

CO2 in solution. Density of the solution is 1.04 kg/L. Molecular weight of DAPOL is 89.

07

Q.4 (a) The analysis of limestone gives 60% CaCO3, 33.5% MgCO3 and rest inerts. It is

treated with 12% aqueous sulphuric acid by mass to obtain pure CO2. An excess

of 15% of the acid over the stoichiometric amounts is used to ascertain that the

reaction goes to completion. Based on the treatment of 500 kg limestone,

calculate: (a) the amount of 100% (by mass) sulphuric acid required, (b) the

amount of the residue, (c) the analysis of the residue left in the vessel, and (d) the

moles of CO2 produced.

08

(b) Discuss the importance of recycling and bypassing operation. 06

OR

Q.4 (a) A fertilizer plant manufactures ammonia using water gas and producer gas as raw

materials. The compositions of the gases are given below.

Analysis , % of by volume

Component Water gas Producer gas

N2 2 63

H2 51 5

CO 43 25

CO2 4 5

Ar Nil 2

Total 100 100

Both the gases are mixed in proper proportions to provide a stoichiometric

mixture of nitrogen and hydrogen after converting carbon monoxide to cabon

dioxide using steam. Calculate:(a) the kmol of water gas and the producer gas

required to obtain 100 kmol of dry mixed gas, (b)the analysis of dry mixed gas,

and (c) the theoretical amount (in kg) of steam required to convert CO to CO2 per

100 kmol of dry mixed gas.

12

(b) Give classification of fuel in brief. 02

3

Q.5 (a) A thermic fluid is used as a heating medium in a particular process. A pump sucks

the thermic fluid at atmospheric pressure and 473 K. The circulation rate is 10000

L/h. The fluid discharged from the pump, passes through a heater where it receives

the heat from the product gases of combustion. The heat transfer rate is 232.6 kW.

The motor of the pump consumes 1.1 kW. The overall mechanical efficiency of the

pump and motor is 50%. The pressure of the fluid at the outlet of the heater is 100

kPa g. Assume Kinetic energy change, potential energy change, friction losses and

heat losses to the surrounding are negligible. If the mean specific gravity and mean

heat capacity of the fluid are 0.75 and 2.68 kJ/(kg.K) respectively at the operating

condition, calculate the outlet temperature of the fluid.

08

(b) Explain standard heat of reaction, standard heat of formation and standard heat of

combustion.

06

OR

Q.5 (a) Oil is to be extracted from meal by a continuous counter current extractor. The

unit is charged with 1000 kg/hr meal based on oil-free solids. Untreated meal

contains 0.4 kg oil and 0.025 kg benzene per kg oil-free meal. Fresh solvent is

benezene containing 1.5% oil (mass %). The ratio of the fresh solvent to the oil-

fresh meal is kept at 0.065 kg/kg. The solid meal retains 0.507 kg solution per kg

solid. The solution retained by the meal contains 11.83% oil (mass %). Make a

complete material balance find and the composition and the amount of overflow

from the extractor. The process is shown in diagram below.

Charge 1000 kg/hr meal

Liquid: 0.4 kg oil and

0.025 kg benzene per kg of solid

Extractor

Solvent Underflow

Oil : 1.5% Solid: 100 kg/hr

Benzene: 98.5% Solution: 11.83% oil, 88.17% benzene

09

(b) A producer gas with the composition by volume, 27.3% CO, 5.4% CO2, 0.6% O2,

66.7 % N2 is burnt with 20% excess air. If the combustion is 98% complete,

calculate the composition by volume of the flue gases.

05

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III • EXAMINATION – WINTER • 2014

Subject Code: 2130504 Date: 30-12-2014

Subject Name: Process Calculation

Time: 02.30 pm - 05.00 pm Total Marks: 70 Instructions:




4. Atomic weights: C:12, H:1,O:16, S:32, Cl:35.5,

Na:23,N:14,Mg:24,B:11,Si:28,Al:27,Fe:56,Zn:65

Q.1 (a) (i) The diameter and hieght of a vertical cylindrical tank are 5 ft and 6ft

respectively. It is full up to 65% hieght with carbon tetrachloride (CCl4), the

density of which is 1.6 kg/L. Find the mass in Kilograms.

04

(ii) Convert: (a) 2.1gm/cm3 to lb/ft

3 (b) 550 kPa to Torr (c) 700

oR to

oF 03

(b) A gas mixture has the following composition by volume: SO2-8.5%,O2-10 %

and rest is nitrogen.Find (1) the avg. Molar mass of the gas mixture, (2) the

composition by mass, and (3) the density of the mixture in kg/m3 at 473 K and

202.65 kPa gauge.

07

Q.2 (a) An aqueous soution of acetic acid of 35% concentration (by mass) has a density

of 1.04 kg/L at 25oC. Find the molarity, Normality and Molality of the solution.

07

(b) The analysis of a sample of glass yields 7.8% Na2O, 7.0% MgO, 9.7% ZnO,

2.0% Al2O3, 8.5% B2O3 and 65.0% SiO2 (by mass). Convert this composition

into mole%.

07

OR

(b) A waste acid from nitrating process contains 20% HNO3, 40% H2SO4, and 40%

water by weight. This acid is concentrated to contain 40% HNO3, 50 % H2SO4

by the addition of concentrated H2SO4 containing 99% H2SO4 and concentratd

Nitric acid containing 95% HNO3. Calculate the weight of waste and

concentrated acid that must be obtaining 1000 kg of desired mixture.

07

Q.3 (a) An aqueous solution of pyridine containg 27% (by wt.) pyridine and 73% (by

wt.) water is to be extracted with chloro-Benzene. The feed and solvent are

mixed well in batch extractor and the mixture is then allowed to stand for phase

separation. The exract phase conains 11% pyridine, 88.1%chlorobenzene and

0.9% water b weight. The raffinate phase contains 5% pyridine and 95% water

by weight. Calculate: (1) The quantities of two phases (2) The weight ratio of

solvent to feed based on 100 kg of feed.

07

(b) The feed to acontinous fractionating column analysed by weight 28% benzene

and 72% toluene. The analysis of the distilate shows 52 % (by weight) benzene

and 5 % (by weight) benzene was found in the bottom product.Calculate the

amount of distillate and bottomproduct per 1000 kg of feed per hour. Aslo

calculate the percent recovery of benzene.

07

OR

Q.3 (a) 2000 kg of wet solids containing 70% solids by weight are fed to tray dyer

where it is dried by hot air. The product finally obtained is found to contain 1%

moisture by weight, calculate: (1) kg of water removed from wet solids (2) kg of

the product obtained.

07

(b) Discuss about recycling and By passing operations. 07

2

Q.4 (a) In the Decon process for the manufacture of chlorine, a dry mixture of

hydrochloric acid gas and air is passes over a heated catalyst which promotes

oxidation of acid. Air is used in 30% excess of htat theoritically require.

Calculate the weight of air supplied per kilogram of acid.

07

(b) A solution of ferric chloride in water contains 64% FeCl3 by weight. Calculate

the amount of FeCl3.6H2O which will crystallise at 300 K from 1000 kg of feed

solution. The solubility of FeCl3 at 300 K is 68.3% by weight FeCl3.

07

OR

Q.4 (a) Gaseous benzene reacts with hydrogen in presence of Ni catalyst as:

C6H6 (g) +3H2 (g) ------- C6H12 (g). 30%excess hydrogen is used above that

required by above reaction. Conversion is 50% and yield is 90%. Calculate the

requirement of benzene and hydrogen gas for 100 moles of cyclohexane.

08

(b) Define: (1) Heat of reaction (2) Heat of combustion (3) Std. heat of formation

(4) Heat capcity.

06

Q.5 (a) Flue gas leaving the boiler stack at 523 K has following composition on mole

basis CO2- 11.31%, H2O-13.04%, O2-2.17% and N2-73.48%. Calculate the heat

lost in 1 kmol of gas mixture above 298 K using heat capacity data given below

Cp= a+bT+cT2+dT

3 in kJ/kmol K.

Gas a b*103 c*10

6 d*10

9

CO2 21.3655 64.2841 -41.0506 9.7999

H2O 32.4921 0.0796 13.2107 -4.5474

N2 29.5909 -5.141 13.1829 -4.968

O2 26.0257 11.7551 -2.3426 -0.5623

08

(b) (i) Calculate the heat of formation of glycerol liquid (C3H8O3) at 298 K from its

elements using Hess’s law. Data: Heat of foramtion of CO2 (g) = (-393.51

kJ/mol), Heat of formation of H2O (l) = (-285.83 kJ/mol), Heat of combustion of

glycerol liquid at 298 K= (-1659.10 kJ/mol).

03

(ii) Calcuate the standard heat of reaction of the following reaction and also

suggests weather reation is (Exothermic/Endothermic).

(COOH) 2(s) -------- HCOOH (l) +CO2 (g). using following Data:

Component ΔHoc, kJ/mol at

298K

(COOH)2(s) -244.76

HCOOH(l) -254.64

03

OR

Q.5 (a) Discuss proximate analysis and ultimate analysis of coal. 07

(b) The orsat analysis of the flue gases by mole is as given below: CO2-11.4%, O2-

4.2% and N2-84.4%. Assuming that complete combustion takes place. Calculate

(1) the % excess air (2) find the C: H ratio in the fuel.

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III (OLD) - EXAMINATION – SUMMER 2017

Subject Code: 130504 Date: 05/06/2017 Subject Name: Process Calculation Time: 10:30 AM to 01:30 PM Total Marks: 70

Instructions:




4. Atomic Mass: H:1, O:16, S:32, P:31, Cl:35.5, K:39, Mn:55, C:12, N:14, Zn:65.4, S:32

Q.1 (a) In a double effect evaporator plant, the second effect is maintained under

vacuum of 345 torr. Find the absolute pressure in kgf/cm2, kPa, atm, N/m2, bar,

psi and mm Hg.

07

(b) Convert the following:

(1) 300 g/l H2SO4 to normality (2) 2.75 N H3PO4 to g/l

(3) 150 g/L HCl to molarity (4) 3 M KMnO4 to normality

07

Q.2 (a) A gas mixture has the following composition by volume:

Ethylene: 35.6%, Benzene: 24.5%, Oxygen: 1.3%, Methane: 15.5%, Ethane

20.0%, Nitrogen: 3.1%.

Find: (a) the average molar mass of the gas mixture, (b) the composition by

mass and (c) the density of gas mixture in kg/m3 at NTP.

07

(b) The average molar mass of a flue gas sample is calculated by two different

engineers. One engineer uses the correct molar mass of 28 for N2 and

determines the average molar mass to be 30.08, the other engineer, using an

incorrect value of 14, calculates the average molar mass to be 18.74. (i)

Calculate the vol% of N2 in the flue gases. (ii) If the remaining components of

the flue gases are CO2 and O2, calculate the volume % of each of them.

07

OR

(b) A weight of 1.10 kg of carbon dioxide occupies a volume of 33 liter at 300 K.

Using the Van der Waals equations of state, calculate the pressure.

Data: For CO2, take a = 3.60 [(m3)2.kPa]/(kmol)2 and b = 4.3 x 10-2 m3/kmol.

07

Q.3 (a) In the Deacon process for manufacturing chlorine, hydrochloric acid gas is

oxidized with air. The reaction taking place is:

4HCl + O2 = 2Cl2 + 2H2O

If the air is used in excess of 30% of that theoretically required and if the

oxidation is 80% complete, calculate the composition by volume of dry gases

leaving the reaction chamber.

07

(b) The shift reaction is a very important reaction in the gas processing industry.

CO + H2O = CO2 + H2

If a and b are the percent carbon monoxide in the dry inlet and outlet gas

mixtures to and from the shift converter respectively. Prove that moles of CO

converted (x) per 100 moles of inlet gas mixture can be calculated by using the

formula.

x = 100(a – b)/[100 + b]

07

OR

Q.3 (a) Zinc sulphide ore containing 74% ZnS and 26% inerts are roasted in a burner.

Assume complete combustion of the ore to SO2 with dry air at 300K and 750

mm Hg. The burner is supplied with 55% excess air over the stoichiometric

amount required for the complete roasting of the ore. The gases are passed

through V2O5 catalyst bed were nearly 98% of SO2 gets converted to SO3. The

14

2

converter gases are passed through an absorption tower where all SO3 is

absorbed in the form of H2SO4 of 90% strength. It is desired to produce 1000

kg/h of 90% acid by spraying pure water at the top of absorption tower.

Calculate: (a) the analysis of the burner gases, (b) the analysis of the converter

gases, (c) the quantity of the ore to be roasted per hour and (d) the volumetric

flow rate of the air entering the converter in m3/h.

Q.4 (a) The heat capacity of carbon monoxide is given by the following equation.

Cp = 6.395 + 6.77 x 10-4 T + 1.3 x 10-7 T2

where Cp = cal/(gmol)C, T = 0C

What is the enthalpy change associated with heating carbon monoxide from

500 0C to 1000 0C?

06

(b) Obtain the expression relating the heat of reaction and the temperature of

reaction.

SO2(g) + ½ O2(g) = SO3(g)

Also calculate the heat of reaction at 700 K using the following Cp0 data.

Cp0= a + bT + cT2 KJ/Kmol K

H0f298 a b x 103 c x 106

(KJ/gmol-K)

SO2 -296.81 24.77 62.95 -44.26

O2 0.0 26.026 11.755 -2.3426

SO3 -395.72 22.04 121.6 -91.87

08

OR

Q.4 (a) A solution of ethyl alcohol containing 8.6% alcohol is fed at the rate of 1000

kg/hr to a continuous distillation column. The product (distillate) is a solution

containing 95.5% alcohol. The waste solution from the column carries 0.1% of

alcohol. All percentages are by weight. Calculate (a) the mass flow rate of top

and bottom products in kg/hr and (b) the percentage loss of alcohol.

07

(b) Isothermal and isobaric absorption of SO2 is carried out in a packed tower

containing Raschig rings. The gases enter the bottom of the tower containing

14.8% SO2 by volume. Water is distributed at the top of the column at the rate

of 16.5 liter per second. The total volume of the gas handled at 101.3 kPa and

303 K is 1425 m3/hr. The gases leaving the tower are found to contain 1% SO2

by volume. Calculate the %SO2 by weight in the outlet water.

07

Q.5 (a) A fuel gas constitutes of CO2: 3.4%, C2H4: 3.7%, C6H6:1.5%, O2: 0.3%,

CO:17.4%, H2: 36.8%, CH4: 24.9% and N2:12.0% (on mole basis). It is burnt

with air in a furnace. The Fyrite analyzer indicated 10 mole% CO2 (on dry

basis) in the flue gases. Find: (a) the percent excess air used and (b) the

complete Orsat analysis.

07

(b) Oil is to be extracted from meal by a continuous counter-current extractor. The

unit is charged with 1000 kg/hr meal based on oil-free solids. Untreated meal

contains 0.4 kg oil and 0.025 kg benzene per kg oil free meal. Fresh solvent is

benzene containing 1.5% oil (mass%). The ratio of fresh solvent to the oil fresh

meal is kept at 0.665 kg/kg. The solid meal retains 0.507 kg solution per kg

solid. The solution retained by the meal contains 11.83% oil (by mass). Make

the complete material balance and find the composition and amount of overflow

from the extractor.

07

OR

Q.5 (a) Discuss in detail about proximate and ultimate analysis of coal. 07

(b) Define Dry bulb temperature, Wet bulb temperature, Dew point, Absolute

humidity, Relative humidity, Humid heat and Humid volume for air-water

contact operation.

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III(OLD) • EXAMINATION – WINTER 2016


Subject Name:Process Calculation

Time: 10:30 AM to 01:30 PM Total Marks: 70 Instructions:

1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks.

Atomic weight: Ca=40, C=12, O=16, H=1, Mg=24, N=14, K=39, S=32

Q.1 (a) Vapor pressure of benzene in the temperature range of 7.5˚C to 104 ˚C can be

calculated using the following Antoine Equation

Where p = vapor pressure in Torr (mmHg) and

t= Temperature in ˚C

Convert above equation in SI Units.

07

(b) By titration, it was found that a sample of water contains hardness equivalent to

500 mg/L (ppm) CaCO3. Assuming that the water contains temporary hardness

in 60% Ca(HCO3)2 form, and 40% Mg(HCO3)2 form, find the concentrations of

both in water.

07

Q.2 (a) Ethanol is present in the aqueous solution to the extent of 1000 mg/L. Find

TOC and ThOD of the solution in mg/L.

07

(b) With the neat sketch explain the use of recycling, bypassing and purging

operations.

07

OR

(b) Convert followings:

1. 50 lb/ft3 to gm/cm3

2. 294 gm/L H2SO4 to Normality

07

Q.3 (a) Fresh juice contains 15% solids and 85% water by weight and is to be

concentrated to contain 40 % solids by weight. In single evaporation system, it

is found that volatile constituents of juice escape with water leaving the

concentrated juice with a flat taste. In order to overcome this problem, part of

the fresh juice bypasses the evaporator. The operation is shown schematically in

below figure.

Calculate (i) the fraction of juice that bypasses the evaporator and (ii) the

concentrated juice product per 100 kg fresh juice fed to the process.

07

(b) The NH3- Air mixture containing 0.2 kg NH3 per kg air enters into absorption

system where ammonia is absorbed in water. The gas leaving the system is 07

55 %

solids

Solids 15 % Solids Fresh

Juice

Evaporator Concentrated juice

40 % Solids By pass juice

15 % Solids

2

found to contain 0.004 kg NH3 per kg of air. Find the % recovery of ammonia.

OR

Q.3 (a) Gaseous benzene reacts with hydrogen in presence of Ni catalyst. 30% excess

hydrogen is used above that theoretical required. Conversion is 50% and yield

is 90%. Calculate the requirement of benzene and hydrogen gas for 100 moles

of cyclohexane produced.

07

(b) A distillation column separates 10000 kg/hr of a 50% benzene and 50%

toluene. The product recovered from the top contains 95% benzene while the

bottom product contains 96% toluene. The stream entering condenser from the

top of the column is 8000 kg/hr. A portion of the product is recycled to the

column as reflux and the remaining withdrawn as top product. Find the ratio of

the amount refluxed to the product.

07

Q.4 (a) Develop the energy balance equation for steady state flow of incompressible

fluid. 07

(b) Write a short note on analysis of coal. 07

OR

Q.4 (a) Calculate the heat required to raise the temperature of 1 kmol pure sulfur

dioxide from 300 to 1000 K. Use the following equation for CP data.

07

(b) An aqueous solution of K2CO3 is prepared by dissolving 44 g K2CO3 in 100 g

water at 293 K. Find molarity, normality and molality of the solution. Take

density of solution as 1.3 kg/lit.

07

Q.5 (a) Define latent heat. State various equations used to calculate latent heat. 07

(b) A sample of fuel oil has C/H ratio 9.33 (by mass) and contains sulfur to the

extent 1.3% (mass). The GCV of the fuel is measured to be 41785 kJ/kg at

25°C. Calculate its NCV at 25 °C. Latent heat of water vapor at 25 °C is 2442.5

kJ/kg.

07

OR

Q.5 (a) A heat exchanger for cooling hot oil uses 10000 kg/hr of cooling water, which

enters the exchanger at 294 K. The hot oil at the rate of 5000 kg/hr enters at 423

K and leaves at 338 K and has an average heat capacity of 2.51 KJ/kg K.

Calculate the outlet temperature of the water.

07

(b) Write short note on Classification of fuels. 07

*************

1



BE - SEMESTER–III EXAMINATION – SUMMER 2016


Subject Name:Process Calculation Time:10:30 AM to 01:30 PM Total Marks: 70 Instructions:


2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks.

4. Atomic wt.:

O :16, C:12,K:39,H:1,N:14,S:32,Zn:65.4,Cl:35.5,Cu:63.5,Ca:40,Fe:56,Na:23

Q.1 (a) The analysis of a sample of glass yields 7.8%Na2O, 7.0%MgO, 9.7%ZnO,

2.0%Al2O3, 8.5%B2O3 and 65%SiO2 (by weight).Convert this composition into

mole%.

07

(b) Answer the following:

1)Define: (i) Molarity (ii)Molality (iii)Normality

2) What is Ideal Gas Law?

3)1Atmospheric pressure = ----------- Psi.

4) Write down different forms of conversion of temperature.

5) What is Steady state process?

07

Q.2 (a) In a double effect evaporator plant the second effect is maintain under vacuum

of475torr (mmHg).Find the absolute pressure in Kgf/cm2, Kpa, atm, N/m2, bar,

Psi, and mmHg.

07

(b) A solution of Caustic soda in water contains 20% NaOH (by weight) at

333K(600C).The density of the solution is 1.196 kg/l.Find the Molarity,

Normality and Molality of the solution.

07

OR

(b) Cracked gas from a petroleum refinery has the following composition by

volume methane 45%, Ethane10%, ethylene 25%, Propane 7%, Propylene 8%,

n-Butane 5% .Find (a) Average mol.wt.of gas mixture. (b)the composition by

weight and (c) Specific gravity of the gas mixture.

07

Q.3 (a) Classify the material balance .Discuss the various methods involved for solving

material balance problems without chemical reactions. 07

(b) It is required to make 1000 kg mixed acid containing 60%H2SO4,32%HNO3and

8%water by blending (i) the spent acid containing 11.3% HNO3,44.4%

H2SO4and 44.3%H2O (ii) aqueous 90% HNO3, and (iii) aqueous 98%

H2SO4.All percentages are by weight. Calculate the quantities of each of the

three acids required for blending.

07

OR

Q.3 (a) Discuss in detail about recycling and by passing operations.

07

(b) Soya bean seeds are extracted with hexane in batch reactors. The flacked seeds

Contains18.6% oil, 69.0%solids and12.4% moisture. At the end of the

extraction process cake is separated from the hexane oil mixture. The cake

analysis yields 0.8%oil, 87.7%solids and 11.5% moisture. Find the percentage

recovery of oil. All percentage is on wt.basis.

07

Q.4 (a) A Mixture containing 47.5%acetic acid and 52.5% water (by weight) is being

separated by the extraction in a counter – current multistage unit. The operating

temperature is 297K (24oC) and the solvent used in pure isopropyl ether. Using

07

2

the solvent in the ratio of 1.3 kg/kg feed, the final extractoincomposition on a

solvent free basis is found to be 82%byweight of acetic acid. The raffinateis

found to contain 14% by weight of acetic acid on a solvent free basis. Calculate

the percentage of acid of the original feed which remains unextracted.

(b) What will be the yield of Glauber salt (Na2SO4.10H2O) if a pure 32%solution is

cooled to 293K (20oC) without any loss due to evaporation?

Data: Solubility of Na2SO4 in water at 293K (20oC) is 19.4kgper 100kg water.

07

OR

Q.4 (a) Temperature of pure Oxygen is raised from 350 to 1500K. Calculate the

amount of heat to be supplied for raising the temperature of 1kmoloxygen using

the following Cp0 data.

Cp0 = a +bT +cT2+ dT3 kg/kmol K

a bx102 cx106 d x103

26.0257 11.7551 - 2.3426 -0.5623

07

(b) A pilot plant reactor was charged with 50kg naphthalene and 200kg (98% by

mass) H2SO4.The reaction was carried out for 3 hours at 433K.The reaction

goes near to completion. The product distribution was found to be

18.6%monosulphate naphthalene (MSN) and81.4% disulphonate naphthalene.

Calculate: (a) the quantities of monosulphonate naphthalene (MNS) and

disulphonate naphthalene (DNS) products and (b) the analysis of the products.

07

Q.5 (a) The dry bulb temperature and dew point of a humid air were found to be 302K

(29oC) AND 291K (18oC) respectively. The barometer reads 100kpa (750torr).

Compute (a) the absolute molal humidity (b) the absolute humidity (c) the

percentage RH (d) the percentage saturation (e) the humid heat and (f) the

humid volume.

07

(b) Define the term with reference to air-water humidification operation :

(a) Dry-Bulb Temperature (d) Relative Humidity (g) Dew Point

(b) Absolute Humidity (e) Humid Heat

(c) Percentage Humidity (f) Humid Volume

07

OR

Q.5 (a) Discuss the brief about Proximate analysis and Ultimate analysis of coal. 07

(b) The Orsat analysis of the flue gases from a boiler house chimney gives CO2:

11.4%, O2:4.2% and N2:84.4 %( mole %).

Assuming that complete combustion has taken place,(a) calculate the % excess

air and (b) find the C:H ratio in the fuel.

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III EXAMINATION – WINTER 2015



Time: 2:30pm to 5:30pm Total Marks: 70 Instructions:




Atomic Weight: C=12, H=1, O=16, Cl=35.5, N=14, S=32

Q.1 (a) Vapor pressure of benzene in the temperature range of 7.5˚C to 104˚C can be

calculated using the following Antoine equation.

Where P= Vapor Pressure in Torr

t= temperature in ᵒC

Convert the above equation in SI Units

07

(b) 1. The volumetric flow rate of kerosene in an 80mm nominal diameter pipe is

7.5 imperial gallons per minute. Taking the density of kerosene as 0.8 kg/dm3,

find the mass flow rate in kg/s.

2. 240 Btu/lb ˚ F = _______ J/gm K

07

Q.2 (a) A vent Stream from ethylbenzene plant has a composition: 66% H2, 33% CH4

and 1 % other components. It is passed through a pressure swing adsorption unit

where hydrogen is recovered as 98% pure stream with 2 % CH4 as an impurity.

Recovery of hydrogen is 85% at a feed pressure of 50 bar. Calculate the

composition of reject stream.

07

(b) Explain in brief bypass, recycle and purge operation. 07

OR

(b) The feed water to the reverse osmosis plant has dissolved solids to the extent of

5000 mg/L. The feed to product ratio (on mass basis) is 4:3. The treated water

(Product) from the plant contains 600 mg/L of solids. Find the dissolved solids

in the reject streams.

07

Q.3 (a) Derive the energy balance equation for steady state flow process of an

incompressible fluid.

07

(b) The orsat analysis of the flue gases from a boiler house chimney gives CO2:

11.4%, O2: 4.2%, and H2:84.4 % (mole%). Assuming that complete combustion

has taken place, (a) Calculate the % excess air and (b) find C: H ratio in the

fuel.

07

OR

Q.3 (a) Write a short note on Proximate analysis of Coal. 07

2

(b) Chlorobenzene is nitrated using a mixture of nitric acid and sulphuric acid.

During the pilot studies, a charge consisted of 100 kg of chlorobenzene, 106.5

kg of 65.5% (by mass) nitric acid, and 108 kg of 93.6% (by mass) sulphuric

acid. After two hours of operation, the final mixture was analyzed. It was found

that the final product contained 2% unreacted chlorobenzene. Also, the product

distribution was found to be 66 % p-nitrochlorobenzene and 34% O-

nitrochlorobenzene. Calculate

(a) The analysis of charge

(b) The % conversion of chlorobenzene and

(c) The composition of the product mixture.

07

Q.4 (a) A mass of 1 kg of carbon dioxide occupies a volume of 33 L at 27 ˚C. Using the

van der Waals equation of state, calculate the pressure.

Data for CO2: take a=3.6 [(m3)2kPa]/[kmol]2, and b = 4.3*10-2 m3/kmol

07

(b) An aqueous solution of acetic acid of 35% concentration (by mass) has a

density of 1.04 kg/L at 25 ˚C. Find the molarity, normality and molality of the

solution.

07

OR

Q.4 (a) Glycerin, weighing 600 mg, is dissolved in pure water to make a final solution

of 1 liter. Find the TOC and ThOD of the solution.

07

(b) A gas mixture has the following composition by volume:

Component % Composition (by

vol)

Ethylene 30.6

Benzene 24.5

Oxygen 1.3

Methane 15.5

Ethane 25.0

Nitrogen 3.1

Find (1) The average molar mass of the gas mixture (2) The composition by

mass & (3) The density of the mixture in kg/m3 at NTP

07

Q.5 (a) Explain the classification of fuels. 07

(b) Chlorinated Diphenyl (Diphyl A-30) is heated from 40 ˚ C to 280 ˚C at the rate

of 4000 kg/h in an indirectly fired heater. In this particular temperature range,

the heat capacity of the fluid is given by the equation

kJ/kg K

Where T is in K.

Calculate the heat to be supplied to the fluid in the heater.

07

OR

Q.5 (a) Explain the followings terms:

1. Standard heat of formation and Standard heat of combustion

2. Sensible heat and latent heat

07

3

(b) Obtain an expression relating the heat of reaction and the temperature of the

reaction

SO2(g) + (1/2)O2(g) = SO3(g)

Using the same expression, calculate the heat of reaction at 502 ˚C

Following data for CP :

Component a b*103 c*106 d*109

SO3 22.036 121.624 -91.867 24.369

SO2 24.771 62.948 -44.258 11.122

O2 26.026 11.755 -2.343 -0.562

Standard heat of formation for SO3 and SO2 are -395720 and -296810 kJ/kmol

respectively.

07

*************

1

Seat No.: _____ Enrolment No.______

GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER– III EXAMINATION – SUMMER 2015

Subject code: 130504 Date: 02/06/2015 Subject Name: PROCESS CALCULATION Time: 02.30pm-05.30pm Total Marks: 70 Instructions:

1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks. 4. Atomic Weights: C:12, H:1, O:16, S:32, Zn:65.4, K:39. Mg: 24.3, N:14,

Cu:63.5, Fe:55.8, Ca: 40, Na : 23

Q.1 (a) An industrial-strength drain cleaner contains 5 kg of water and 5 kg NaOH. What are the weight fraction and mole fraction of each component in the drain cleaner container?

03

(b) The analysis of sewage gas sample from a municipal sewage treatment plant is given below on a volume basis.

Ethane 65% Carbon Monoxide 33% Ammonia 2% H2S, SO2 Traces

Find (a) the average molecular weight of the gas, and (b) the density of the gas at STP

04

(c) In case of liquids, the local heat transfer coefficient for long tubes and using bulk temperature properties is expressed by the empirical equation h= 0.023 G0.8 × k0.67 × cp

0.33/ (D0.2×μ0.47) where h= heat transfer coefficient, Btu/(hr ft2 0F) G= mass velocity of liquid, lb/(ft2s) cp= heat capacity, Btu/(lb 0F) D= diameter of tube, ft and K=Thermal conductivity in Btu/(hr ft 0F) μ = viscosity of liquid, (lb/ft s) Convert the empirical equation into SI units.

07

Q.2 (a) An aqueous solution of K2CO3 is prepared by dissolving 86 kg K2CO3 in

200 kg water at 293 K. Find molarity, normality and molality of the solution. Take sp. gravity of solution as 1.29.

07

(b) A mixture of CuSO4.5H2O and FeSO4.7 H2O weighs 100gm. It is heated in an oven at 378 K to evaporate the water of hydration. The mass of mixture after removal of water is 59.78gm. Calculate the mass ratio of CuSO4 to FeSO4 in the mixture.

07

OR (b) It is required to make 1000 kg mixed acid containing 60% H2SO4, 32%

HNO3 and 8% water by blending (i) spent acid containing 11.3% HNO3, 44.4% H2SO4, 44.3% H2O(ii) aqueous 90% HNO3 (iii) aqueous 98% H2SO4. All percentages are by weight. Calculate the quantities of each of three acids required for blending.

07

2

Q.3 (a) Explain the following terms with reference to chemical process (1) Process flow diagram (2) P & I diagram (3) Degree of freedom (4) Limiting component (5) Recycling operation (6) By passing operation (7) Excess component

07

(b) A heat exchanger for cooling hot oil uses 10000 kg/hr of cooling water, which enters the exchanger at 294 K. The hot oil at the rate of 5000 kg/hr enters at 423 K and leaves at 338 K and has an average heat capacity of 2.51 KJ/kg K. Calculate the outlet temperature of the water.

07

OR Q:3 Zinc sulphide ore containing 74% ZnS and 26% inerts are roasted in a

burner. Assume complete combustion of the ore to SO2 with dry air at 300K, 50% of the stoichiometric amount air required for the complete roasting of the ore. The gases are passed through V2O5 catalyst bed was nearly 98% of SO2 gets converted to SO3. The converter gases are passed through an absorption tower where all SO3 is absorbed in the form of H2SO4 of 90% strength. It is desired to produce 1000 kg/h of 90% acid by spraying pure water at the top of absorption tower. Calculate: (a) the analysis of the burner gases, (b) the analysis of the converter gases, (c) the quantity of the ore to be roasted per hour and (d) the volumetric flow rate of the air entering the converter in m3/h.

14

Q.4 The Analysis of limestone gives 60% CaCO3, 33.5% MgCO3 and rest

inert. It is treated with 12% aqueous sulphuric acid (by mass) to obtain pure CO2. An excess of 15 % of the acid over the stoichiometric amounts is used to ascertain that the reaction goes to completion. Based on the treatment of 500 kg limestone, Calculate (a) the amount of 100% (by mass) sulphuric acid required (b) the amount of residue (c) the analysis of the residue left in the vessel and (d) the moles of CO2 produced.

14

OR Q.4 (a) Pyrite ore is roasted in chamber plant for making sulphuric acid. The

gases leaving the roaster are at 775 K and have molar composition SO2 = 7.09%, O2 = 10.55%, SO3 = 0.45% and N2 = 81.91%. Calculate the heat content of 1 kmol gas mixture over 298.15 K by using the given heat capacity data: Component a b x103 c x 106 d x 109 ------------- -------- --------- ---------- --------- SO2 24.7706 62.9481 -44.2582 11.122 O2 26.0257 11.7551 -2.3426 -0.5623 SO3 22.0376 121.624 -91.8673 24.3691 N2 29.5909 -5.141 13.1829 -4.968

Where, Cp is in KJ/Kmol K and T in K.

07

Q:4 (b) Using Watson equation, Calculate laten heat of vaporization of (1) acetone at 400 K (2) carbon disulphide (CS2) at 450 K

07

3

T1 (Boiling point temp) K

Component Laten heat of vap at T1, K (kJ/kmol)

Tc K

n

329.4 Acetone(C3H6O) 29121 508.1 0.38 319.0 Carbon

disulphide(CS2) 26736 552.0 0.38

Q.5 (a) Define the following terms with reference to air-water

humidification operation: (1) Dry-bulb temperature (2) Absolute humidity (3) Percentage humidity (4) Relative humidity (5) Humid heat (6) Humid volume (7) Dew point

07

(b) 10,000 kg of an aqueous solution containing 29.6% (by wt.) anhydrous sodium sulfate at 413 K is charged to the crystallizer. During the cooling operation, 5% of the initial water is lost by evaporation and Na2SO4.10H2O is crystallized out. The mother liquor is found to contain 18.3% (by wt.) anhydrous sodium sulfate. Calculate the yield of crystals and the quantity of mother liquor. Molecular wt. of Na2SO4 = 142

07

OR Q.5 (a) Discuss Proximate and Ultimate analysis of coal 07 (b) A furnace is fired with fuel oil. The Orsat analysis of flue gases by

volume is as given below: CO2 = 10.6%, O2 = 6% and N2 = 83.4% Calculate:

(a) the percent excess air used and (b) the C: H ratio in the fuel oil, assuming that the fuel does not

contain nitrogen.

07

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III • EXAMINATION – WINTER • 2014







4. Atomic weights: C:12, H:1, N: 14, O:16, Na: 23, Cl:35.5, K:39

Q.1 (a) A gas mixture has the following composition by volume:

Ethylene: 30.6%, Benzene: 24.5%, Oxygen: 1.3%,

Methane: 15.5%, Ethane: 25.0%, Nitrogen: 3.1%. Find:

i) the average molecular weight of the gas mixture,

ii) the composition by weight, and

iii) the density of the mixture in kg/m3 at 101.3 kPa and 273 K.

08

(b) Find out value of the universal gas constant R in the following units:

i) atm.lit/mol.K

ii) J/mol.K

iii) cm3.atm/kmol.K

iv) kPa.m3/kmol.K

06

Q.2 (a) Classify the material balance. Discuss various methods involved for solving

material balance problems without chemical reactions.

07

(b) The conductance of a fluid-flow system is defined as the volumetric flow rate,

referred to a pressure of one torr (133.322 Pa). For an orifice, the conductance

C can be computed from

389.2 /T

C A ft sM

Where A = area of opening, ft2

T = temperature, oR

M = molecular weight

Convert the empirical equation into equation with SI units.

07

OR

(b) An aqueous solution of K2CO3 is prepared by dissolving 43 kg K2CO3 in 100 kg

water at 200c. The density of the solution is measured to be 1.3 kg/liter. Find out

molarity, molality and normality of the solution.

07

Q.3 (a) Explain importance of process flow sheet in chemical industry with a typical

example.

07

(b) Write a short note on recycling and bypassing operations. 07

OR

Q.3 (a) In the Deacon process for manufacturing chlorine, hydrochloric acid gas is

oxidized with air. The reaction taking place is:

4HCl + O2 → 2Cl2 + 2H2O

If air is used in excess of 30% of that theoretically required and if the oxidation

is 80% complete, calculate the composition by volume of dry gases leaving the

reaction chamber.

07

2

(b) Heat capacity data for gaseous SO2 are reported by following equation:

C0

mp = 43.458 + 10.634 ×10-3

T - 5.945 × 105/ T

2, J/mol.K

Calculate the heat required to raise the temperature of 1 mol pure sulphur

dioxide from 300 K to 1000 K.

07

Q.4 (a) Define the following:

i) heat of reaction

ii) heat of formation

iii) heat of combustion

iv) sensible heat

v) latent heat

vi) conversion

vii) yield

07

(b) Define GCV and NCV for fuels. Give its importance. Also give names of the

equipments used for measuring CV of solids, liquids and gases.

07

OR

Q.4 (a) In an electrochemical cell, the current is passed at the rate of 1130 amperes for

18000 seconds through a solution containing copper sulphate. At the end of the

process, 1.12 m3 oxygen (at NTP) is collected. Find: i) the amount of copper

liberated, and ii) the current efficiency of the cell.

07

(b) A solution of ethyl alcohol containing 8.6% alcohol is fed at rate of 1000 kg/h to

a continuous distillation column. The product is a solution containing 95.5%

alcohol. The waste solution from the column carries 0.1% alcohol. All % are by

weight. Calculate i) the mass flow rate of top & bottom product in kg/h and ii)

the % loss of alcohol.

07

Q.5 (a) Discuss in brief about proximate analysis and ultimate analysis of coal. 07

(b) Define the following terms with reference to air-water humidification operation:

i) dry-bulb temperature

ii) absolute humidity

iii) percentage humidity

iv) relative humidity

v) humid heat

vi) humid volume

vii) dew point

07

OR

Q.5 (a) The Orsat analysis of the flue gases from a boiler house chimney gives CO2:

11.4%, O2: 4.2% and N2: 84.4% (mol%). Assuming that complete combustion

takes place,

i) calculate the % excess air, and

ii) find C:H ratio in the fuel.

07

(b) A mixture of aniline and water containing 11.8% by weight of aniline is cooled

from 1000C to 40

0C with the help of cooling water. Find the amount of heat

removed by cooling 100 kg of mixture. The specific heat Cp can be expressed by

the equation. Cp = a + bT + cT2 (kcal/kg.

0C)

where the constants a, b, c are :

For aniline: a = 1.407, b = 2.467×10-3

, c = -6.08×10-6

For water: a = 0.6741, b = 2.8×10-3

, c = 8.3×10-6

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III • EXAMINATION – SUMMER • 2014







Q.1 (a) List the various systems of units and give the example of any four derived units in

each system of units. 07

(b) Explain Ideal gas law, Dalton’s law and Raoult’s law. 07

Q.2 (a) A continuous distillation column is used to regenerate solvent for use in a solvent

extraction unit. The column treats 200 kmol/hr or a feed containing 10 mol %

ethyl alcohol and the rest water. The overhead product is 89 mol % alcohol and

the bottom product is 0.3 mol % alcohol. The overhead is sent to the extraction

unit and bottom is waster. What is the daily requirement of make- up alcohol in

the solvent extraction unit?

07

(b) Explain the material balance of extractor. 07

OR

(b) Explain the material balance of crystallizer. 07

Q.3 (a) Write the general material balance equation and explain the concept of limiting

and excess reactant. 07

(b) Calculate the molar quantity of all the product materials when 1 kg-atom of sulfur

is burned with 20% excess air and will produce 95% SO2 and remaining SO3. 07

OR

Q.3 (a) Calculate the enthalpy of the tank filled with liquid having following data:

Pressure inside the tank=7000 kPa, volume of liquid=7.0685 m3

Volume of tank = 14.137 m3, Internal energy of liquid=5.3 * 10

9 J

07

(b) The molal heat capacity of CO is given by CP=26.586+7.582*10-3

T – 1.12*10-6

T2 where CP is in kJ/kmol K and T is in K. Calculate the meanmolal heat capacity

in the temperature range of 500-1000 K.

07

Q.4 (a) Define: Sensible heat, Latent heat, Heat of reaction, Heat of solution, Adiabatic

reaction.

07

(b) Wood containing 40% moisture is dried to 5% moisture. What mass of water in

kilograms is evaporated per kg of dry wood?

07

OR

Q.4 (a) Explain the concept of recycle, bypass and purge stream. 07

(b) Calculate the yield of Na2SO4.10H2O if a pure 32% solution is cooled to 20 o

C

without any loss due to evaporation. Take solubility of Na2SO4 in water at 20 oC

is 19.4 kg/100 kg water.

07

Q.5 (a) Explain proximate analyses. 07

(b) Crude oil is found to contain 87.1% carbon, 12.5% hydrogen and 0.4% sulfur (by

mass). Its GCV at 25 oC is measured to be 45071 kJ/kg oil. Calculate its NCV at

25 oC. Latent heat of water vapor=2442.5 kJ/kg

07

OR

Q.5 (a) Explain ultimate analyses. 07

(b) The orsat analysis of the flue gases from a boiler house chimney gives CO2=

11.4%, O2=4.2% and H2=84.4%(mole %). Assuming that complete combustion

has taken place, calculate the % excess air.

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III • EXAMINATION – WINTER 2013







4. At. wt: Na = 23, O= 16, H=1, N=14, C=12, Cl=35.5, S=32.

Q.1 (a) Differentiate between intensive property and extensive property. 02

(b) Define: molarity, molality, normality and solubility. 04

(c) Iron metal weighs 200lb and occupies a volume of 11.7L. Find the density in

kg/m3.

04

(d) The available nitrogen in an urea sample is found to be 45% by mass. Find the

actual urea content in the sample. 04

Q.2 (a) Explain different methods of solving material balance problems without

chemical reaction with suitable examples. 08

(b) A natural gas has the following composition by volume: CH4 – 83.5%, C2H6 –

12.5% and N2 – 4%. Calculate (i) the average molecular weight and (ii) density

at standard condition.

06

OR

(b) Carbon tetrachloride is made as per the following reaction:

CS2 + 3Cl2 � CCl4 + S2Cl2

The product gases composition is as follows: CCl4 – 23.3%, S2Cl2 – 23.3%, CS2

– 1.4% Cl2 – 32% (mol %). If CS2 is the limiting reactant then calculate:

(i) Percentage of conversion.

(ii) Percentage of excess reactants used.

06

Q.3 (a) A spent lye sample contains 9.6% glycerol and 10.3% NaCl salt. It is

concentrated at the rate of 5000 kg/h in a double effect evaporator until the final

solution contains 80% glycerol and 6% salt. 4.5% glycerol is lost by

entrainment. All the percentage are by mass. Determine:

(i) the evaporation taken place in the system.

(ii) the amount of salt crystallized out from the evaporator.

07

(b) The analysis of 15000 L of a ags mixture at standard condition is as follows:

SO2 – 10%, O2 – 12% and N2 – 78%. How much heat must be added to this gas

to change its temperature from 300C to 425

0C? The Cpm values in cal/gmol

0C

are given as follows:

Gas SO2 O2 N2

Cpm at 300C 10 6.96 6.80

Cpm at 4250C 11 7.32 7.12

07

OR

2

Q.3 (a) Define: (i) Heat of formation (ii) heat of reaction. 02

(b) Differentiate between: (i) Sensible heat and latent heat (ii) Endothermic and

exothermic reactions. 06

(c) Heat capacity for gaseous SO2 is given by the following equation:

C0 = 43.458 + 10.634 × 10

-3 T - 5.945 × 10

5/T

2

Calculate the heat required to raise the temperature of 1 kmol pure SO2 from

300K to 1000K.

06

Q.4 (a) (i) Write a short note on proximate analysis of coal.

(ii) Define: GCV and NCV of fuel. 07

(b) A coal containing 87% Carbon, and 7% H2 and remaining ash is burnt in a

furnace with 40% excess air. Assume complete combustion. Calculate:

(i) the quantity of air supplied per kg of coal burnt.

(ii) the composition of flue gases in wt%.

07

OR

Q.4 (a) (i) Why excess air is provided for combustion process?

(ii) Write a short note on Orsat analysis. 07

(b) The flue gas from a furnace using a hydrocarbon fuel oil analyses as follows by

volume: CO2=16.5%, CO=0.2%, O2=1.5% and rest N2. Calculate:

(i) the percentage composition by weight of fuel burnt.

(ii) The percent excess air used.

07

Q.5 (a) With a neat sketch show the material balance for the following unit operation:

(i) distillation (ii) evaporation. 07

(b) A mixture containing 47.5% acetic acid and 52.5% water (by mass) is being

separated by the extraction in a counter-current multistage unit. Pure iso-propyl

ether is used as an solvent. The solvent to feed ratio is 1.3. The final extraction

composition on a solvent free basis is found to be 82% by mass of acetic acid.

The raffinate is found to contain 14% by mass of acetic acid on a solvent free

basis. Calculate the percentage of acid of the original feed which remains

unextracted.

07

OR

Q.5 (a) Discuss humidification operation and define the important parameters for air-

water system. 07

(b) A crystallizer is charged with 7500 kg of aqueous solution at 1040C containing

29.6% by weight of anhydrous Na2SO4. The solution is then cooled to 200C.

During this operation 5% of water is lost by evaporation. Glauber salt

crystallizes out. Find the yield of crystals. Data:

Solubility at 200C = 19.4 g Na2SO4 per 100g water.

Mol. Wt of Glauber salt (Na2SO4.10H2O) = 322.

07

*************

1/2


GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–III • EXAMINATION – SUMMER 2013

Subject Code: 130504 Date: 29-05-2013 Subject Name: Process Calculation Time: 02.30 pm - 05.30 pm Total Marks: 70 Instructions:

1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks. 4. Atomic mass: O: 16, C:12, K:39, H:1, N:14, S:32, Zn:65.4,

Q.1 (a) In the Caustic soda plant, in multiple effect evaporator, the second

effect is maintained under vacuum of 410 torr. Find the absolute pressure in kgf/cm2, kPa, atm, N/m2, bar, psi and mm Hg.

07

(b) An aqueous solution of K2CO3 is prepared by dissolving 86 kg K2CO3 in 200 kg water at 293 K. Find molarity, normality and molality of the solution. Take sp. gravity of solution as 1.3.

07

Q.2 (a) What is Fundamental quantity and Derived quantities? Give units of

following in terms of fundamental quantity: Area, Volume, Work, Power, Mass flow rate and Specific heat.

07

(b) A gas mixture has the following composition by volume: Ethylene: 31%, Benzene: 24%, Oxygen: 1%, Methane: 15%, Ethane: 25%, Nitrogen: balance. Find:

(a) the average molecular mass of the gas mixture and (b) the density of the gas mixture in kg/m3 at NTP.

07

OR (b) A weight of 1.10 kg of Carbon dioxide occupies a volume of 33 liter at 300 K.

Using the Van der Waals equation of state, calculate the pressure. Data: For CO2 , take a = 3.60 [(m3)2-kPa]/(kmol)2 and b = 4.3 x 10-2 m3/kmol

07

Q.3 (a) It is required to make 1000 kg mixed acid containing 60% H2SO4, 32% HNO3

and 8%water by blending (i) spent acid containing 11.3% HNO3, 44.4% H2SO4 and 44.3% H2O, (ii) aqueous 90% HNO3 and (iii) aqueous 98% H2SO4. All percentage are by weight. Calculate the quantities of each of the three acids required for blending.

07

(b) The average molecular mass of a flue gas sample is calculated by two different engineers. One engineer uses the correct molecular mass of 28 for N2 and determines the average molecular mass to be 30.08, the other engineers, using an incorrect value of 14, calculates the average molecular mass to be 18.74.

(a) Calculate the volume% of N2 in the flue gases. If the remaining components of the flue gases are CO2 and O2, calculate the volume % of each of them.

07

OR Q.3 (a) Classify the material balance. Discuss the various methods involved for

solving material balance problems without chemical reactions. 07

(b) Write short note on recycling and bypassing operations. 07

Q.4

Zinc sulphide ore containing 74% ZnS and 26% inerts are roasted in a burner. Assume complete combustion of the ore to SO2 with dry air at 300K and 750

14

2/2

mm Hg. The burner is supplied with 55% excess air over the stoichiometric amount required for the complete roasting of the ore. The gases are passed through V2O5 catalyst bed were nearly 98% of SO2 gets converted to SO3. The converter gases are passed through an absorption tower where all SO3 is absorbed in the form of H2SO4 of 90% strength. It is desired to produce 1000 kg/h of 90% acid by spraying pure water at the top of absorption tower. Calculate: (a) the analysis of the burner gases, (b) the analysis of the converter gases, (c) the quantity of the ore to be roasted per hour and (d) the volumetric flow rate of the air entering the converter in m3/h.

OR

Q.4 (a) With a typical example, explain the terms: Conversion, Yield, Selectivity, Limiting component and Excess component.

07

(b) The heat capacity of carbon monoxide is given by the following equation. Cp = 6.395 + 6.77 x 10-4 t + 1.3 x 10-7 t2 cal/(gmol 0C) Where ‘t’ is in 0C What is the enthalpy change associated with heating carbon monoxide from 500 0C to 1000 0C?

07

Q.5 Liquid benzene, C6H6 at 303 K is mixed and dissolved continuously in liquid

toluene, C7H8 at 373 K in the molar proportion 3:2 in an insulated mixing tank. If the heat of mixing is assumed to be zero, what is the temperature of the mixed solution? Heat capacity data for Benzene and Toluene: Temperature, K Heat capacity(c), KJ/kg.K Benzene Toluene ------------------ ----------------------------------- 283 1.591 1.524 338 2.018 - 358 - 2.236 Assume the variation of the heat capacity is linear with temperature, i.e. c = a + bT KJ/(kg.K) Where a and b are constants.

14

OR

Q.5 (a) Define the following terms with reference to air-water humidification operation:

(1) Dry-bulb temperature (2) Absolute humidity (3) Percentage humidity (4) Relative humidity (5) Humid heat (6) Humid volume (7) Dew point

07

(b) Discuss in brief about Proximate analysis and Ultimate analysis of coal. 07

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