Pretest Unit Op Lab Sem 2 20152016 (1)

FACULTY OF CHEMICAL & NATURAL RESOURCES ENGINEERING

PRETEST

INSTRUCTIONS TO CANDIDATE:

Answer all the questions. Submit the answer of each experiment according to the experiment week to your instructor before start each of the experiments.

Pretest BKF 3731Unit Operation Lab

COURSE : UNIT OPERATION LABORATORY

COURSE CODE : BKF3731

LECTURER : FATMAWATI ADAM

IZIRWAN IZHAB

MOHD NAJIB RAZALI

MOHD ZULKIFLI MOHAMAD NOOR

NOOR SABRINA AHMAD MUTAMIM

SAIFUL NIZAM HASSAN

SHALYDA BINTI MD SHAARI

SITI KHOLIJAH ABDUL MUDALIP

SUNARTI ABD RAHMAN

ZATUL IFFAH MOHD ARSHAD

SESSION/SEMESTER : SESSION 2015/2016 SEMESTER II

SECTION/LECTURER: ______________

Name ID Number Group

QUESTION 1 (Crystallization)

a) The Van Hoff plot of Epsom salt in ethanol at 298, 308 and 318 K is y = -6860.4x +

15.154. Find the entropy S and enthalpy from this set of crystallisation data of Epsom

salt in ethanol solvent using Van Hoff plot.

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(7 Marks)

b) List TWO (2) effect of crystal solid shape in chemical engineering application.

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(3 Marks)


c) Arrange the steps of crystallisation process which begins from the solution until the

solid crystal form.

Crystallisation Solubility Nucleation Supersaturation Undersaturation

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(10 Marks)




QUESTION 2 (Thin Film Evaporator)

a) Describe the concept of thin film evaporator unit. Provide ONE (1) EXAMPLE of

thin film evaporator in industrial process.

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(4 Marks)

b) A single-effect thin film evaporator concentrates 9072 kg/h of sucrose solution (RI =

1.3346) entering at 311 K to a final concentration of sucrose (RI = 1.3353). The vapor

pressure of the evaporator is 101.325 kPa. The data for sucrose concentration with the

respective refractive index is shown in Table 1. Calculate the amount of vapor and

liquid product.

(Hint: Feed = Liquid + Vapor; FXF = LXL; XF is the feed concentration % (w/w) of sucrose;

XL is the final concentration % (w/w) of sucrose as concentrate).


Table 1: The refractive index at respective sucrose concentration

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Sucrose concentration % (w/w)

Refractive Index

0 1.33331 1.33452 1.33593 1.33744 1.3388

(10 Marks)


c) Explain the effect of increasing the vacuum pressure on temperature, flow rate and

the refractive index of distillate (vapor) and bottom (liquid) products in a thin film

evaporator.

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(5 Marks)




QUESTION 3 (Short Path Distillation)

a) Briefly discuss the concept of short path distillation?

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(4 Marks)b) Provide TWO (2) examples of short path distillation in industry.

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(3 Marks)

c) Describe the experimental method for short path distillation system.

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(8 Marks)


d) List the shutdown procedures for short path distillation unit.

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(5 Marks)




QUESTION 4 (Sieve Tray Distillation)

a) Draw the distillation unit block diagram when operated in total reflux condition.

Demonstrate the theoretically mass and energy balance for the system.

(6 Marks)


b) Explain the function of measuring device refractometer during sieve tray distillation

experiment.

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(2 Marks)

c) Describe the effects of having high reboiler power to the process in sieve tray distillation

experiment.

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(2 Marks)

d) Discuss on how the value of HETP can be used to evaluate the efficiency of a

fractionating column.

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(2 Marks)


e) Shown in table below are the data for the experiment. Complete the table with values for

mole fraction and HETP values. Show your calculation.

Column Height (mm) 1000

Refractive Index pure ethanol 1.3621

Refractive Index pure water 1.3317

Refractive Index mixture 1.3575

Heater Power (kW)

Distillate BottomsNumber of trays

HETP (mm)Refractive

IndexMole

FractionRefractive

IndexMole

Fraction

2.0 1.3582 1.3382 8

3.0 1.3550 1.3372 10

4.0 1.3426 1.3371 12

(18 Marks)




QUESTION 5 (Solid Liquid Extractor Unit)

a) Briefly explain the process flow of the Solid – Liquid Extraction experiment unit.

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(5 Marks)

b) Is there any effect of solid-liquid extraction efficiency when less amount of water at low temperature condition is used.________________________________________________________________________

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(3 Marks)


c) Is the solubility important for a short-period solid-liquid extraction of various sea salts?

State THREE (3) solubility criteria/character to affect a higher yield of extraction

process. List EIGHT (8) examples of soluble salts.

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(12 Marks)




QUESTION 6 (Absorption Column Unit)

a) Briefly describe the principle of absorption column.

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(4 Marks)

b) Explain the role of packed materials used in absorption column for gas absorption.

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(4 Marks)

c) The packed material employed in this experiment is Raschig rings or ceramic Intalox

saddle. The packed material employed in this experiment is Raschig rings or ceramic

Intalox saddle. Explain the effect of changing the packed materials on column efficiency

and operation.

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(4 Marks)


d) What is flooding point?

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(4 Marks)

e) List 2 precautions before handling packed absorption column.

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(4 Marks)




QUESTION 7 (Pressure Swing Adsorption)

a) Briefly explain the concept of pressure swing adsorption unit. Provide an example of

solid adsorbent and typical industrial process that use this technology.

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(5 Marks)

b) Figure 1 illustrates a breakthrough curve of oxygen adsorption in pressure swing

adsorption system which field with carbon molecular sieve. Provide explanation of

oxygen adsorption in the system based on the curve.


Figure 1: Breakthrough concentration curve

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(4 Marks)

c) State TWO (2) factors that affect the adsorption efficiency in PSA._____________________________________________________________________

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(2 Marks)


Concentration ratio, c/co

Time, t

0.05

d) Briefly discuss the oxygen and nitrogen hazard during handling PSA_____________________________________________________________________

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(4 Marks)

END OF QUESTION PAPER


Pretest Unit Op Lab Sem 2 20152016 (1)

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