Template Student Laboratory Guide Oct 08 Plant 3A.doc2013 (1)

7/28/2019 Template Student Laboratory Guide Oct 08 Plant 3A.doc2013 (1)

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FACULTY OF ENGINEERING AND THE BUILT ENVIRONMENT

DEPARTMENT OF CHEMICAL AND METALLURGICAL ENGINEERING

NAME OF COURSE:

CHEMICAL ENGINEERING PLANT (IIIA)

NQF

LEVEL

NQF

CREDIT

S

QUALIFICATION & SAQA IDCOURSE

CODE

Diploma In CHEMICALENGINEERINGSAQA ID No.: NLRD49744..

(CMP33AT)

COMPILED BY : Mr M. Mosesane 2009

REVISED BY : Mr V. Hlongwane 2010

STUDENT LABORATORY


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COPYRIGHT : Tshwane University of Technology

Private Bag X680

PRETORIA

0001

Printed and distributed by :

FACULTY OF ENGINEERING AND

BUILT ENVIRONMENT


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ORGANISATIONAL COMPONENT CONTENTS:

1. Welcome.....................................................................................................................5

2. LABORATORY Staff...................................................................................................6

2.1 Contact Details......................................................................................................6

2.2 Staff availability.....................................................................................................6

3. Requirements, resources and recommended material.............................................7

3.1 Requirements for the course.................................................................................8

4. Code of conduct.......................................................................................................10

5 Attendance............................................................................................................14

5.1 LABORATORY, HEALTH & SAFETY RULES AND REGULATIONS...............14

BASIC RULES...........................................................................................................14

5.2 Responsibilities of students................................................................................14

6. Assessment..............................................................................................................15

6.1 Assessment methods and criteria......................................................................15

6.2 Assessment rules................................................................................................15

6.3 Marking system .................................................................................................15

6.4 predicate/Year mark...........................................................................................16

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6.5 Moderation ........................................................................................................17

6.6 Promotion requirements.....................................................................................17

7. laboratory course content and schedule..................................................................17

7.1 schedule of laboratory sessions and assignments.............................................17

7.2 Learning outcomes and assessment criteria.....................................................19

7.3 Generic outcomes and critical cross-field outcomes.........................................21

8. Glossary of terms ....................................................................................................21

9. Assessment Records ..............................................................................................21

10 Example of a practical report...............................................................................22

11. Appendices ...........................................................................................................26

11.1 Flocculation and coagulation.............................................................................26

11.2 sedimentation experiment.....................................................................................29

Up = true particles hindered velocity (m/s).................................................31

12. Example of a practical report.................................................................35

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SECTION A ORGANISATIONAL COMPONENT

1. WELCOME

Welcome to laboratory session of Chemical Engineering Plant IIIA. This part

of the course provides an introduction and represents advanced knowledge

in unity operation and is offered via experimental work, problem-based

work or project-based work over 8 weeks. The course is structured in such

a way as to master theoretical concepts and principles and various

practical skills to provide a sound foundation for the study of Distillation,

Absorption and Drying to complement the major courses in the qualification

and pave the way for more advanced learning in B-Tech in Chemical

engineering. We trust you will enjoy the course, and find it interesting and

informative.

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2. LABORATORY STAFF

2.1 CONTACT DETAILS

NAMECAMPU

S

ROOM

NO

TEL NO

E-MAIL

CONSULTA

TION

TIMES

ACADEMIC

FUNCTION

Dr R.

MbayaPretoria

(012) 382 3513

[email protected]

.za

Lecturer

Mr M.J

MosesanePretoria

B2

R127

(012) 382 4655

mosesanejm@t

ut.ac.za

08H00

16H00

Technologis

t

Mentors

2.2 STAFF AVAILABILITY

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If, after attending class and making every effort from your side to master

content, you still have problems with understanding key concepts or

principles or their application, lecturers are available for consultation.

To consult your lecturer, make an appointment by calling his office or see/

call the secretary at (012) 382 3597/3514 for an appointment.

To consult your technologist, make an appointment by calling his office at (

012) 382 4655 or call the secretary at (012) 382 3514.

3. REQUIREMENTS, RESOURCES AND RECOMMENDED

MATERIAL.

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3.1 REQUIREMENTS FOR THE COURSE

3.1.1 PRESCRIBED RESOURCES

The following tables indicate what literature and other resources are

essential for successful completion of this course. You are strongly advised

to acquire all the prescribed resources.

PRESCRIBED RESOURCES

CATEGORY DESCRIPTION WHERE TO FIND COST LEVY

CALCULATOR Scientific Bookstore

COMPUTER Computer lab

HARDWARE Laboratory

Journal/Notebook ( not a

page or exam pad )

SOFTWARE

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EQUIPMENT SedimentationStudy Kit and

Jar test

equipment

COMPONENTS

3.1.2 RECOMMENDED RESOURCES

The following recommend resources will enhance your understanding andknowledge in this course, and you are encouraged to use the following

additional resources.

RECOMMENDED RESOURCES

CATEGORY AUTHOR NAME PUBLISHE

R

ISBN NO

BOOKS

MANUALS Laboratory

Manual

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GUIDES

RECOMMENDED ELECTRONIC MATERIAL & WEBSITES

VIDEO

CD

DVD

WEBSITES

4. CODE OF CONDUCT

Safety

Laboratory safety is the top priority and this requires all people in the lab to

be observing safe practices at all times!

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Safety glasses must always be worn by everyone in the laboratory.

Make sure you understand how the experimental apparatus works and

what all

of the adjustments do before you attempt to operate it.

Be sure you have asked, and received an answer, from the Technician

about any possible hazards related to your experiment before attempting

to operate it.

Care must be used in the handling of chemicals to avoid spills and to

avoid contact with the skin.

B. Laboratory Format and Procedures

1. Organization of Student Groups and Laboratory Projects

Students will organize into groups of five persons. Each group is to perform

three projects during the semester. (A roster of the groups and a schedule

of projects will be supplied separately.)

A group leader, who is in charge of directing the work for the lab,

should be selected by, and from among, the members of the group.

(This responsibility should rotate among the members.) All group

members must be prepared for the laboratory and contribute equally

to the laboratory work and preparation of the reports. However, the

group leader is in charge of assigning and coordinating tasks for the

laboratory period and maintaining the group notebook. He or she is

ultimately responsible for making sure that everything is done to

ensure a successful experiment.

2. Laboratory Session 1

At the beginning of the first session for a given experiment, a

paragraph describing the experimental plan and procedure

should be submitted to the Technician who is in charge at

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that time. A discussion between the Technician and the

students will take place to ensure that students have an

accurate plan of action.

3. Laboratory Session 2

The Technical report should be submitted to the Technician in charge of the

experiment. A summary discussion of the report with the instructor will be

conducted in the laboratory.

4. Session 3

The laboratory will be open to gather additional data if needed. The

lecturer will be available for consultations during the first hour of the

laboratory period. During this session examination of the experimental

apparatus for the next assigned project should be performed by each

group.

5. Final Technical Report .

The final Technical report is due at the beginning of the next scheduled

laboratory period following Session 3. There are no exceptions to this

deadline. The reports are to be submitted to one of the department

secretaries in the Chemical Engineering office or to the Technician. During

the week following the day on which the final report was submitted, the

group should schedule a meeting with the lecturer for the discussion of the

written report. Each member of the group should be prepared to defend

and/or discuss any part of the final report.

6. Laboratory Notebook

Part of the purpose of the chemical engineering laboratories is to learn

good laboratory and research practices. An important aspect of this is

safety. Another important aspect is record-keeping and documentation. In

industry you will find that all experiments have to be carefully recorded in

an official laboratory notebook and signed by the investigator on a daily

basis. To help foster these professional practices, each group is required to

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keep a laboratory notebook documenting the group's work. In the notebook

should be kept a neat, labeled and dated record of all work associated with

the experiment, including a copy of the precis, all raw data, the settings on

the experimental controls, any problems encountered in the experiment

and what was done to fix them and why, all calculations, a copy of your

progress report, etc. The laboratory notebooks will be handed in at the endof the semester and will contribute to the laboratory participation portion of

your grade.

7. Student Responsibilities in the Laboratory

Condition of Working Area. Students are responsible for the condition

of their working area at the end of each laboratory period.

All power to the equipment and instruments should

be turned off, and steam and cooling water flowsshould be shut off.

Glassware used should be cleaned and dried.

Any equipment or instrumentation malfunctionsshould be reported promptly to the Technician orassistants.

Checkout before Leaving Laboratory. The students must have their

notebooks initialed by a Technician prior to leaving at the end of the

laboratory period. At that time the Technician will check the working area

and take information about any equipment or instrumentation problems.

8. Grading/Marking

Report grading is done by the lecturers who are in charge of a given

experiment. This grade will be based on the written report, the oral

defense and other pertinent factors (e.g., if you are totally unprepared to

do an experiment, you will be docked.) Grades for this course will be

determined by the grades on the three experiments as well as your

laboratory participation. The laboratory participation portion of your gradein will include how well you followed laboratory safety guidelines (did you

wear safety glasses at all times in the lab? did you follow the special safety

precautions required for each experiment?), attendance, tardiness,

participation, professionalism, how effective a group leader you were, and

the quality of your laboratory notebook. Both laboratory instructors and

teaching assistants will contribute towards this portion of your grade.

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5 ATTENDANCE

Regular attendance of the chemical engineering plant (IIIA) lectures is of

primary importance. It is the learners responsibility to sign the register

each week. A minimum attendance of 75% is mandatory for all courses

including practical In a 30 week year, 8 classes that have not been

attended and for which you have not furnished a valid doctors letter or

other proof of extenuating circumstances, amounts to 25% absenteeism.

This level of absenteeism will lead to exclusion from the final moderation at

the end of the year, which means that you will fail the course and will have

to repeat it the following year.

5.1 LABORATORY, HEALTH & SAFETY RULES AND REGULATIONS

5.1.1. LABORATORY RULES

BASIC RULES

Always wear a laboratory coat in the laboratory.

Do not wear open shoes in the laboratory.

Do not eat or drink in the laboratory.

No horse-playing in the laboratory.

Always ask the technician if you are not sure of anything.

5.2 RESPONSIBILITIES OF STUDENTS

It is your responsibility to make a success of learning in this course. To this

end you are encouraged to attend class, write practical reports and hand in

your assignments/projects on the set due dates.

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SECTION B LEARNING COMPONENT

6. ASSESSMENT

6.1 ASSESSMENT METHODS AND CRITERIA

Assessment of this laboratory course will include experimental work,problem-based work, Project-based works and assignments, as indicated in

the schedule under section 2.2. The purpose of assessment is to determine

whether you have achieved the learning outcomes. The various assessment

methods therefore will focus on criteria that will enable the lecturer(s) to

determine whether you have achieved the learning outcomes and

mastered the required skills. The assessment criteria relevant to each

learning outcome are detailed in section 2.

6.2 ASSESSMENT RULES

The general rules of TUT regarding assessment apply. You are advised to

familiarise yourself with these rules, as they are applied stringently.

6.3 MARKING SYSTEM

Subject Max Mark Actual Mark

1. Title Page 1

2. Abstract 6

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3. Introduction 2

4. Theoretical Background 3

5. Procedure 2

6. Results 6

7. Discussion of Results 10

8. Conclusion and

Recommendations

4

9. Literature Cited 1

10. Nomenclature 1

11. Organization and Neatness 2

Appendix

A1 Raw Data 2

A2 Data analysis and Sample

Calculations

10

TOTAL 50

6.4 PREDICATE/YEAR MARK

(Indicate how the laboratory mark will be calculated and any rules you have

in this regard. Also indicate the percentage it contributes to the

predicate/year mark. Distinguish between semester modules and year

subjects) Predicate marks are put on the faculty notice boards. If you

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have queries about your mark, you must immediately consult your

course lecturer (contact details are given above), before predicate

day. Once the predicate mark is entered on TUTs mainframe computer,

the mark cannot be changed.

6.5 MODERATION

The lecturer of the subject will be responsible to moderate all practical

report.

6.6 PROMOTION REQUIREMENTS

The leaner has to obtain the minimum of 50% in the practical report in

order to pass.

7. LABORATORY COURSE CONTENT AND SCHEDULE

This course comprises of an experimental component, problem-based

component and a project-based component. Your mastery of the required

skills is assessed at regular intervals. More importantly, the application of

theory is assessed through problem-based- or project-based assignments

or projects.

The following outline provides an overview of the content to be covered in

this course and the ways in which your progress will be assessed.

7.1 SCHEDULE OF LABORATORY SESSIONS AND ASSIGNMENTS

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DURATION THEME

EXPERIMENTAL/

PROBLEM-

BASED/

PROJECT-BASED

COMPLETION DATE*

Week 1-4SEDIMENTATION

(Learning Outcome 1)

To studydifferent settlingregimes and todetermine the

relationshipbetweenconcentrationand settlingvelocity.

To study theconcepts offlocculation andanti-flocculationand apply themto thickener

operation anddesign.

To be able tosize thickenersbased onparticle sizes,fluid viscosities,and desiredconsistencies.

SEDIMENTATION

Week 5-8Coagulation andflocculation

(Learning Outcomes 2)

To conduct jartest on a natural

Coagulation andflocculation

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surface water inorder toestimate anoptimumdosage ofaluminium

sulphate orferric sulphatefor the removalof suspendedmatter orcolour.

To observe therate of flocformation andsedimentation.

7.2 LEARNING OUTCOMES AND ASSESSMENT CRITERIA

The following tables clearly indicate what you have to achieve (the learning

outcomes) and how you will be assessed (assessment criteria) to determine

whether you have achieved the required knowledge and competences:

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LEARNING OUTCOME 1:

SEDIMENTATION, COAGULATION AND FLOCCULATION

Assessment criteria Assessment method

Report writing skills

Data collection and interpretation

Task performance

Written report(marking the report)

Questions and Answers

Observation

LEARNING OUTCOME 2

Assessment criteria Assessment method


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7.3 GENERIC OUTCOMES AND CRITICAL CROSS-FIELD OUTCOMES

8. GLOSSARY OF TERMS

The following technical terms are used in this course, and you should be

familiar with these terms and their meanings.

Flocculants, coagulation, settling velocity, rate of settling, sedimentation,

thickener

Sources used for the compilation of the glossary:

9. ASSESSMENT RECORDS

The following guideline for the preparation of report writing are attached to

serve as examples of the implementation of the assessment criteria and

assessment method, as listed in the table 3.1, and you should be familiar

with these examples to prepare and orientate yourself of how the various

assessment criteria are used and applied in the various assessment

methods.

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Compliance with Critical

cross-field Outcomes

Compliance with Generic

Engineering and Built

Environment Outcomes

Mathematics and Statistics

Communication and written skills


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10 EXAMPLE OF A PRACTICAL REPORT

Guidelines for the Preparation of Written Reports

A technical report is a medium commonly used by scientists and engineers

to communicate the results of their work. Frequently the report is the only

tangible product and thus the only evidence for evaluation of the work.

Consequently, it deserves careful attention to quality, packaging, and

distribution.

It is important that the writer(s) of an engineering report keep inmind the needs and interests of the anticipated readers of the

report. The laboratory report should be written with the same

professionalism that would be used to present the results of a major

industrial project. The people who will read it, and need to draw

conclusions from it, can be expected to have technical training, but

probably would not be familiar with the details of the work.

A good report of technical work quantitatively states significant results of

experiments and computations and explains how they were obtained, what

they mean, and how they are useful. The report should be clear, concise,

and accurate. Often the structure of the report must conform to specific

conventions. A format for laboratory reports that is to be used in this

course is given below.

1. Title Page

The title of the report is followed by names of the authors and laboratory

group, the date of submission, and identification of the institution or

organization supporting the work (Tshwane University of Technology,

Department of Chemical & Metallurgical Engineering, CMP33BT).

2. Abstract

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The abstract is a tightly written summary, typically 100 to 300 words long.

This section is important because it is the first impression your report will

make to a reader, and it could very well be the only part of it he or she will

read! (Because of its importance, it is a significant part of the overall

grade.) The abstract should be written as stand alone section of just text.

Its independence means that the use of symbols, tables, and graphs as wellas literature references should be avoided. A good abstract states the

principal objective of the investigation, describes the methodology used

and summarizes the results and conclusions in statements as quantitative

and as general as possible.

The abstract should provide ranges of the experimental parameters (e.g.

the Reynolds number was varied from 100 to 10000), report the most

important results and state how these values compare to expected (i.e.,

literature) ones. (e.g., values for the friction factor in the laminar flow

regime were consistently 15% higher that the predictions of Poiseuille

flow). If the value of a single variable or a short list of numbers is given,

the numbers should give the uncertainty (e.g., solubility at 25C was 25

3 moles/liter) and of course units should be included.

We recommend that you write the abstract last, when your thoughts are

most clearly in focus (i.e., you know all the answers and thus know what to

say!).

3. Table of Contents

A Table of Contents should be included in the report, including a listing of

the Abstract. Appendices should also be listed. All pages should be

numbered, including tables, figures, and appendices.

4. Introduction

The purpose of the Introduction is to place the work in the perspective of

prior work including key literature references, demonstrate its importance,

and state the specific objectives. The Introduction should not exceed two

pages.

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5. Theory

This section is a short, concise statement of the essential empirical and

theoretical relations to be used in interpreting the data or to be tested by

the data. Equations are usually stated with a reference, along with the

pertinent assumptions and limitations. Brief manipulations may beappropriate, but long derivations are relegated to an appendix. The

physical significance of equation parameters should be pointed out.

6. Experimental

A. Apparatus

The objective of this section of the report is to describe the

experimental set-up in enough quantitative detail to enable thereader to completely understand the experiment. Ranges of

independent variables are cited. The model and supplier of any

unique equipment should be cited. Also, a schematic diagram of the

experimental apparatus should be included.

B. Procedure

The objective of this section of the report is to describe the materials

and methods used to obtain the experimental data. Emphasis isplaced on general procedures that are not routine

7. Results

The data, or a representative fraction of them, must be included in this

section. They should be presented graphically. If there are only a few (i.e.

2-3) numbers, these could put into a table if they can be understood. Data

are often not presented in raw form, but are reduced and shown in the way

most clearly supporting the conclusions. Representation of scatter in datais essential. For example, the experimentally determined heat transfer

coefficient is meaningless unless it is accompanied by units and an

estimated uncertainty. Comparison of data with theoretical predictions

and/or previously published values should be included whenever possible.

This may require searching for information in reference books or research

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articles. Comment briefly on unique aspects of the results, in particular its

accuracy. Also comment on the range of the variables covered.

Each graph or diagram is assigned a number (e.g., Figure 1) and should

have a caption that is descriptive of the information contained in the figure.

A restatement of the information on the axes is not an acceptable title.

8. Discussion

All important interpretations which follow from the results and the

underlying theory are logically and quantitatively compared in the

Discussion section. The positive conclusions, comparison with literature

data, and the significance applicability, and reproducibility of the results

are stressed. Quantitative statements about the accuracy and precision of

the results are required. However, when a detailed error analysis isessential to the work, it should be relegated to an Appendix.

9. Conclusions and Recommendations

This section is a summary of the most significant conclusions developed in

the preceding section. Quantitative statements are best. Useful

recommendations to improve the experiment and to extend the work to

other systems, should be included here.

10. Literature Cited

Only references cited in the report are to be listed is this section since it is

not a bibliography covering all references but only the most pertinent ones.

Footnotes on individual pages of the report are not to be used. References

cited in the text of the final project report should give the last name of the

author (both authors when only two; first author et. al. when more than

two) and the corresponding page numbers. An example is given below.

The Reynolds number can be interpreted as the ratio of inertial to viscous

forces at work in the fluid (Denn 37-39).

References are to be listed in alphabetical order according to author or

equivalent and should not be numbered. Use Chemical Abstracts Service

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Source Index journal abbreviations. For the previous example the citation

would be the following:

Richard, J.F. and Zaki, W.N. 1954. Sedimentation and fluidization, Part 1,Transactions of the Institution of Chemical Engineers

. Coulson, J.M., Backhorst, J.R., Harker, J.H., and Richardson J.F. vol 2

4th ed,. Particle technology and separation process. 1991

11. Nomenclature

Symbols used in the report are defined immediately after they are

presented the first time. This section of the report lists all of the symbols

used. Units should be included.

12. Appendices

The appendices contain material of secondary importance: sample

calculations (a sample of all calculations done for the experiment must be

included in the report), error analysis, derivation of theoretical relations,and perhaps graphs, calibration curves and/or schematics. Note that the

appendices should be named in the order of which they appear in the final

project report. In other words Appendix A should be the first appendix

referred to in the text of the report.

11. APPENDICES

11.1 FLOCCULATION AND COAGULATION

JAR TEST PRACTICAL

BACKGROUND

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Coagulation and flocculation processes are an important part of water andwastewater treatment. Coagulation or destabilization of a colloidalsuspension results in joining of minute particles by physical and chemicalprocesses. Flocculation results in formation of a larger settleable structureby bridging. These processes commonly used to remove suspended matteror colour. Adsorption of ionic forms also occurs to varying degrees

depending on the constituents in the water or wastewater.

The jar test is a laboratory technique for determining the most effectivecoagulant, chemical dose, and operating pH for coagulation andflocculation, aluminium or iron salts may be used to coagulate particles andto form settleable flocs composed of the hydrous metal oxide precipitatesand impurities.

Coagulation and flocculation experiments may also be used, in conjunctionwith other tests, to study basic processes including, for example, thekinetics of reaction, and the removal of trace constituents from aqueoussolution.

OBJECTIVES

1. To conduct jar test on a natural surface water in order to estimate anoptimum dosage of aluminium sulphate or ferric sulphate for theremoval of suspended matter or colour.

2. To observe the rate of floc formation and sedimentation.

PROCEDURE

A. DETERMINE OF OPTIMUM COAGULANT DOSAGE

Collect 20 to 50 litres of natural surface water. Analyze the water for pH,turbidity, colour after filtration, and alkalinity. Alternatively, make up asynthetic water sample for testing. Record both the water temperature andambient air temperature.Calculate the amount of alkalinity required to react with the maximumdosage of aluminium or ferric sulphate. If necessary, augment the naturalalkalinity by the addition of 0.1 N Na2CO3 so that the alkalinity will be atleast 0.5 meq/l (25 mg/l as CaCO3).Measure exact 1 litre of water into each jar test reactor. Prepare portions of

the aluminium or ferric sulphate solution which will yield 10 to 50 mg/l asAl2O3 or Fe2O3 when added to the sample aliquots.Mix at 50 rpm to ensure water is completely mixed.Measure chemical volumes to achieve desired dose in each reactor.Increase mixing speed to 250 rpm. Add the chemicals to each reactor nearthe vortex. All reactors should be dosed at the same time.Rapidly mix for 1 min.Reduce mixing to 60 rpm for 9 min.; Observe the reactors at 3 min.

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intervals to detect the formation of flocs. Reduce mixing to 25 rpm for 4min.; Reduce mixing to 10 rpm for 2 min.Turn off mixers and allow particles to settle for 20 min.Measure the turbidity or colour, alkalinity, and pH of the liquid in each jarby sampling at the top, taking care not to disturb the sediment in sampling.Measure the depth of sludge in the beaker.

B DETERMINATION OF OPTIMUM pH

Repeat the jar test of Part A using the observed optimum dosage of ferricsulphate but adjusting sample pH to 6, 7, 8, and 9 with NaOH or H2SO4 priorto adding coagulant.Measure final pH, turbidity or colour of the supernatant of each sample.Measure the depth of sludge in the beaker.Plot turbidity or colour versus pH.

EFFECT OF MIXING (AGGREGATION KINETICS)

Prepare identical (optimum) coagulant dosages for all six beakers.Use the same rapid mix as before but vary the time of slow mix at 30 rpm.Use 5, 10, 15, 20, 30, and 45 minutes for the six jars respectively.Terminate mixing by carefully lifting the paddle from the beaker atappropriate time.Allow 30 minutes for settling.Measure the colour or turbidity and pH of the supernatant in each beaker.

APPARATUS

Jar test apparatus and beakersMagnetic stirrer plus magnetic stirring barsSpectrophotometer or colour comparatorTurbidimeterpH meterAssorted measurement pipettes (1, 5, 10 ml) and volumetric pipettes to 50mlBuretteGlass or plastic funnelsRingstands and rings

MATERIALS

Aluminium sulphate solution, 1 g/l or ferric sulphate solution,1 g/l H2SO4, 2 litres each, 5 x 10-2 M,10-2 M NaOH,, 1 litre, 10-1 MSodium carbonate, 1 litre each, 5 x 10-2 M, 10-2 MIndicators: methyl orange, phenolphthalein

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Synthetic water sample: Add suspended matter with a kaolin,montmorillonite, illite, or bentonite clay and/or the colour with extract fromboiled leaves or with instant coffee to raw water. Turbidity might beincreased to about 40 turbidity units and colour to about 80 colour units(Clay suspension sample should be mixed for 3 days).Buffer solution

Whatman #1 filter paper

REPORT

Prepare tables which facilitate comparisons of coagulant dosages withalkalinity, pH, colour, turbidity, and other changes observed. Plot theinverse of turbidity and colour versus coagulant dosage as part of theanalysis. Plot turbidity versus coagulant dose at different settling times to

determine the influence of floc formation and settling characteristics on theselection of coagulant dosage.Comment on the differences between coagulation with iron and aluminiumsalts. Define the pH ranges over which each salt should result in effectivecoagulation.Determine the rate of aggregation for a particular coagulant dose and pHby plotting the reciprocal of the turbidity versus time. (This would representa second order reaction with respect to turbidity). Also plot the natural logof the reciprocal turbidity (representing a first order reaction) versus time.Determine which gives the best straight line fit of the data and determinethe slope.

References

Richard, J.F. and Zaki, W.N. 1954. Sedimentation and fluidization, Part 1,

Transactions of the Institution of Chemical Engineers.

Coulson, J.M., Backhorst, J.R., Harker, J.H., and Richardson J.F. vol 2 4th ed,.

Particle technology and separation process. 1991.

Geankoplis, C.J Transport Processes and Unit Operations, 3rd., Prantice-Hall,

1993

11.2 SEDIMENTATION EXPERIMENT

1. INTRODUCTION

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Sedimentation is the partial separation or concentration of suspended solid

particles from a liquid by gravity settling. It is a strong function of liquid

viscosity and density, particle size, and concentration of the solution. With

that in mind, experiments can be performed that will allow the engineer to

determine settling times and velocities for liquid-solid suspensions and

slurries. This would enable thickeners to be designed for specific industrialtask.

The sedimentation process is particularly important in the preparation of

industrial or domestic water and purification of wastewater. Many process

applications are also found in metallurgical industry. The beer brewing

industry also has many applications dealing with batch settling and use of

flocculants. Certain clarifiers are added to the beer in order to flocculate

sediment particles so they may later be filtered.

The objective of this experiment is to do settling experiments of the type

that are used to size thickeners for specific industrial applications and to

interpret the results in the context of equipment design.

Objectives:

To study different settling regimes and to determine the relationshipbetween concentration and settling velocity.

To study the concepts of flocculation and anti-flocculation and applythem to thickener operation and design.

To be able to size thickeners based on particle sizes, fluid viscosities,and desired consistencies.

2. Theory

The theoretical ideas used in analysing sedimentation problems

are studied extensively in Chemical Plant course. The methods and

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concepts and concepts covered in this experiment are dealt with in

that class and can be found in the text (2). The main calculations

in the lab are done using the Richardson-Zaki equation and the

Kynch method. The student is urged to have a good grasp of these

concepts when performing this experiment and discuss the aspects

of them thoroughly in the report.

Most correlations used to size thickeners require that the particles behave

according to Stokes law operation is that the Reynolds number must be

less than 0.3. Richardson and Zaki have developed a means to relate the

actual velocity of the particle. With the terminal velocity calculated, Stokes

law can be solved for the diameter of the particle. The Richardson-Zaki

equation is as follows:

=U

UP

T

= Void fraction for the concentration

n = proportional exponent

UP = TRUE PARTICLES HINDERED VELOCITY

(M/S)

UT = terminal velocity, from Stokes law (m/s)

The value of the proportional exponent can be found by:

n = 4.6 + x/D

Where x = particle diameter, in meters

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D = vessel diameter, in meters

Stokes law:

( )v

d g P Ps l=

2

1 8

The Kynch method is a graphical approach that is used to find the settling velocity of a

slurry or suspension over time. However, there are several other constraints that apply

to the Kynch method that should also be kept in mind, such as neglecting wall effects,

assuming uniform particle shape and size, and that the particle velocity reaches zero

at large times .The Kynch method involves constructing tangents to the settling height

and times curves, and the slope of each of these tangents is the velocity at that time.

The most important restriction of the Kynch method is that system must

obey Stokes law. Stokes lawcompares the drag force that resists a settling sphere in

a fluid .the viscosity of that fluid and the shear it creates, and the pressure drag of the

moving sphere, to the terminal velocity of the particle. To prove that a given system of

the particles are within the

Stokes law region, the single particle Reynolds number is calculated. This value must

be below 0.3 for Stokes law to the valid. If this is true, then the settling velocity of the

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particles can be as a function of system characteristics, like particle and fluid densities,

as well as the diameter of the particle.

4. APPARATUS:

To perform this experiment, graduated glass cylinders with a total height of

approximately 1 m are used. The diameter of the cylinder is 0.05 m. The cylinders

should be thoroughly washed and filled with varying concentration of a suspension and

glass beads for the experiment. The suspension to be examined is aC a C O

3 , which is

combined with water to simulate batch settling of fine particles, while glass beads are

mixed with octanol to simulate coarse particles. The settling times are kept by using

the stopwatches provided.

5. METHOD:

The settling experiment is conducted in a cylinder. The suspension C a C O 3 is prepared

at different concentration by weight (to be determined by laboratory supervisor). The

suspension is prepared by mixingC a C O

3 of known quantity with water. The test

column is filled with the suspension up to 0.7 m and agitated with compressed air or

well shaken for about 1 min to provide uniform concentration throughout the depth.

The solids profiles are then determined at different moments of time after agitation.

In addition to profile determination settling of the interface is measured as a function

of time to estimate settling parameters. Graphs at height against time are plotted as

the experiment proceeds. for final compaction reading, a period of 24 hours should

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elapse. Gradients of the initial settling period should be deduced, in order to plot the

initial mass settling rate against concentration.

To determine concentration at any point on the settling curve, a graphical method

employed by Kynch is employed. On the time vs. height graph, a tangent is drawn to

the settling curve, it cuts the vertical axis at a certain point.

The following quantities should be tabulated from reassured data:

Concentration %

Initial solid weight

used (kg)

Volume per unit

weight (m3/kg) *

Height when critical

point reached (m)

Sedimentation Volume

=

H T u b e A r e a

I n i t i a l S o l i d s W e i g h t

C R

Final Sedimentation

height (m)

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Final Volume =

H T u b e A r e a

I n i t i a l S o l i d s W e i g h t

f

Richard, J.F. and Zaki, W.N. 1954. Sedimentation and fluidization, Part

1, Transactions of the Institution of Chemical Engineers.

Coulson, J.M., Backhorst, J.R., Harker, J.H., and Richardson J.F. vol 2 4th ed,.

Particle technology and separation process. 1991.

Geankoplis, C.J Transport Processes and Unit Operations, 3rd., Prantice-Hall,

1993

12. EXAMPLE OF A PRACTICAL REPORT

TSHWANE UNIVERSITY OF TECHNOLOGY

DEPARTMENT OF CHEMICAL AND METTALURGICAL ENGINEERING

REPORT GRADING FORM

Name of Student: ____________________________________________________

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Student Number: _____________________________________________________

Title of Report: ______________________________________________________

Term: _______________________________ DATE: __________________

Subject Max Mark Actual Mark

1. Title Page 1

2. Abstract 6

3. Introduction 2

4. Theoretical Background 3

5. Procedure 2

6. Results 6

7. Discussion of Results 10

8. Conclusion and

Recommendations

4

9. Literature Cited 1

10. Nomenclature 1

11. Organization and Neatness 2

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Appendix

A1 Raw Data 2

A2 Data analysis and Sample

Calculations

10

TOTAL 50

Signed: ____________________________________

Comments:

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