EXPERIMENT MODULE
CHEMICAL ENGINEERING EDUCATION LABORATORY
STIRRED TANK
(TGK)
CHEMICAL ENGINEERING DEPARTMENT
FACULTY OF INDUSTRIAL TECHNOLOGY
INSTITUT TEKNOLOGI BANDUNG
2018
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 2
Contributor:
Dr. IDG Arsa Putrawan, Dr. Sanggono Adisasmito, Dr. Ardiyan Harimawan,
Yoga Sujatnika, Dinna Rizqi Awalia, Dr. Pramujo Widiatmoko
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 3
TABLE OF CONTENT
TABLE OF CONTENT ............................................................................................................. 3
LIST OF TABLE ....................................................................................................................... 4
LIST OF FIGURE...................................................................................................................... 5
CHAPTER I INTRODUCTION ................................................................................................ 6
CHAPTER II PURPOSE AND TARGET OF EXPERIMENT ................................................ 7
CHAPTER III EXPERIMENTAL DESIGN ............................................................................. 8
CHAPTER IV WORK PROCEDURE .................................................................................... 10
BIBLIOGRAPHY .................................................................................................................... 12
APPENDIX A RAW DATA TABEL ...................................................................................... 13
APPENDIX B CALCULATION PROCEDURE .................................................................... 15
APPENDIX C LITERATURE DATA .................................................................................... 17
APPENDIX D JSA CONTROL SHEET ................................................................................. 18
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 4
LIST OF TABLE
Table 1. Data of Tap Water Density and Viscosity Determination . . . . . . . . . . . . . . . . . . . 13
Table 2. Dimension of the Stirred Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 3. Data Characteristic Impeller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 4. Primary Experiment Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 5. Figure Observation of Flow Patterns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 5
LIST OF FIGURE
Figure 1. Simple Stirred Tank Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 2. Type of Stirrer (a) propeller, (b) turbine, (c) paddle . . . ... . . . . . . . . . . . . . . . . . 8
Figure 3. Preliminary Experiment Flow Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Figure 4. Primary Experiment Flow Diagram. . . . . . . ……... . . . . . . . . . .. . . . . . . . . . . . .11
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 6
CHAPTER I
INTRODUCTION
Stirring is an operation aimed at moving the stirred materials, generally carried out to mix
and disperse the material. The stirred material may be two dissolved liquids, solids in a
liquid, a gas in a liquid in bubbles form. Stirring may also be carried out to accelerate heat
transfer, for example by heating the fluid with a coil and / or a heating jacket.
Factors affecting stirring and mixing processes which are the tank configuration, type and
geometry of the agitator, position of the stirrer axis, stirrer rotation speed, and the physical
properties of the stirred fluid. Type and geometry of the mixer is closely related to the stirring
flow patterns that occur. Mixing in the tank occurs because of the rotational motion of the
stirrer in the fluid. This stirring motion 'cuts' the fluid and can cause a moving Eddy current,
creating a flow across the fluid part. The selection of type and geometry of the agitator is
based on the physical properties of the fluid, especially the viscosity. In addition to type and
geometry of the agitator, the speed of stirring also affects circular flow patterns. Excessively
high velocities can lead to whirlpool or so-called vortex. This vortex is not expected in
stirring because it leads to a decrease in the quality of stirring, the entry of air into the fluid,
and over flow of the fluid due to rising fluid surfaces.
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 7
CHAPTER II
PURPOSE AND TARGET OF EXPERIMENT
The purpose of the stirred-tank module experiment is:
1. Learn mixing process of component in a fluid which held in a stirred tank system.
2. Identify factors that affect the effectiveness of mixing.
The target of this experiment is to be able to practice:
1. Derive the correlation of mixing time with rotational speed through the analysis of
dimensionless numbers.
2. Derive the correlation of mixing time with the speed of rotation and time through
analysis of dimensionless numbers.
3. Carry out a visual observation of flow patterns and provide an analysis of the flow
patterns that occur.
4. Determine the optimum mixing conditions.
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 8
CHAPTER III
EXPERIMENTAL DESIGN
The schematic diagram of the stirred tank system circuit used for this experiment can be seen
in Figure 1. The type of agitator consists of 3, shown in Figure 2.
Keterangan gambar
C = height stirrer from the bottom of
the tank
D = diameter of the mixer blade
Dt = diameter of tank
H = height fluid in the tank
J = width baffle
W = width of mixer blade
Figure 1. Simple Stirred Tank Scheme
Figure 2. Type of Stirrer (a) propeller, (b) turbine, (c) paddle
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 9
The tools needed for this practicum are:
1. Set the stirred tank tool
2. Stopwatch
3. Viscometer
4. 25 mL Pycnometer
5. Measuring cylinder
6. Voltmeter
7. Multimeter as amperemeter
8. Pipette
9. Impeller
The list of materials required to carry out this practice is:
1. Tap water
2. Aqua DM
3. Solid grains that are not soluble in water
4. Dyes
The variations done in this experiment are:
1. The speed of the stirrer rotation
2. Type and size of stirrer, propeller, turbine, and paddle.
3. Position of the impeller is center and off-center.
4. Use of baffles.
5. Height of the impeller
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 10
CHAPTER IV
WORK PROCEDURE
The stirring module experiment consists of two parts: a preliminary experiment and a primary
experiment. The stirred tank experiment flow diagram is shown in Figure 3 and 4. A
preliminary experiment was conducted to measure the physical properties of the liquid in the
stirred tank, which are density and viscosity. Measurement of fluid density was carried out
with pycnometer, while the determination of viscosity is done with Ostwald viscometer. Both
tools are selected because they are simple and provide fairly accurate results for dilute
liquids.
The main experiment was conducted to observe the mixing time, which is the time required
to achieve the uniformity of the fluid component in the tank. This mixing time is analyzed by
observing homogeneity of color. Variation of stirring speed is done by speed regulator (but
recorded speed is listed in speed display). The power required for stirring may be calculated
by measuring the voltage and current used by the agitating motor. This voltage and current
measurement is performed using amperemeter and voltmeter mounted on the stirrer. After
measuring the mixing time, the experiment is a flow pattern observation. Observations were
made by observing the movement of granules in the fluid during stirring.
Figure 3. Preliminary Experiment Flow Diagram
Measurement of fluid
temperature with
thermometer
Determination of fluid
viscosity with Ostwald
viscometer
Determination of fluid
density with pycnometer
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 11
Figure 4. Primary Experiment Flow Diagram
Preparation of tools and materials
The impeller is mounted on the stirrer axis. The axis of the mixer is
attached to the stirrer motor. Connect to power and turn it on.
Initial current reading (Io) and initial voltage (Vo)
The stirring speed is adjusted according to the planned variation
Tap water is put into the tank according to the specified volume. Dyes are
inserted according to the specified volume. The mixing time to
homogeneous is recorded.
Solid grains are included for flow pattern observation. The flow patterns
are then drawn and / or recorded.
The reading of the final current (I) and the final voltage (V)
The above experiment series are repeated for variations of stirring type,
stirring speed, axis position, and baffle usage.
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 12
BIBLIOGRAPHY
Mc Cabe, W.L., Unit Operation of Chemical Engineering, 3rd Edition, McGraw-Hill Book
Co., New York, 1978
Perry, R., Green, D.W., and Maloney, J.O., Perry’s Chemical Engineers’ Handbook, 6th
Edition, McGraw-Hill, Japan, 1984
Brodley, and Hershey, Transport Phenomena: A Unified Approach, McGaw-Hill Book Co.,
New York, 1988, Chapter: Application of Mixing
Moo-Young et al., The Blending Efficiencies of Some Impellers in Batch Mixing, AIChEJ,
18 (1), 1972, pp. 178-182
Tatterson, and Gary, B., Fluid Mixing and Gas Dispersion in Agitated Tanks, McGraw-Hill
Book Co., New York, 1991, Chapter 1,2, and 4
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 13
APPENDIX A
RAW DATA TABEL
A.1. Determination of Density and Viscosity of Tap Water
Table 1. Data of Tap Water Density and Viscosity Determination
Repetition I II
Aqua dm temperature (oC)
Empty pycnometer mass (g)
Mass pycnometer + aqua dm (g)
Mass pycnometer + tap water (g)
Aqua dm retention time (s)
Tap water retention time (s)
A.2. Tool Configuration
Table 2. Dimension of the Stirred Tank
Characteristic Value
Diameter
Tank Height
Baffle Amount
Baffle Width
Baffle Thickness
Baffle Length
Table 3. Data Characteristic Impeller
Type Turbin Paddle Propeller
Diameter
Number of leaves
Width of leaves
Length of leaves
Thickness of leaves
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 14
A.3. Main Experiment
Table 4. Primary Experiment Data
Type of Impeller :
Position of Impeller :
Baffle/non-baffle :
N (rpm) Vo (volt) Io (mA) Vo (volt) Io (mA) Time (s)
A.4. Observation of Flow Patterns
Table 5. Figure Observation of Flow Patterns
Type of Impeller :
High speed
( ...rpm)
Low speed
(...rpm)
Baffle Centre
Off-centre
Non-baffle Centre
Off-centre
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 15
APPENDIX B
CALCULATION PROCEDURE
B.1. Determination of Density and Viscosity
… (1)
… (2)
B.2. Analysis of Dimensionless Numbers
1. Reynolds Number
The Reynolds number is a dimensionless number that expresses the ratio between the inertial
force and the viscous force. For systems with stirring, the Reynolds (Re) number is expressed
as:
…(3)
dengan ρ = fluid density, μ = fluid vicosity, dan D = Impeller diameter.
There are three types of flow regimes in the stirring system, namely laminar, transition and
turbulent. The laminar flow regime is obtained on the Reynolds number 10, while the
turbulent occurs at Reynolds number above 104 [Broadkey, 1988].
2. Fraude Number
The Fraude number (Fr) shows the ratio of the inertia force to the force of gravity, expressed
as:
… (4)
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 16
dengan Fr = Fraude number, N = Impeller rotating speed, D = impeller diameter, dan g =
gravity acceleration
Fraude numbers are mainly taken into account in the baffled stirring system. In this system,
the liquid surface shape in the tank is affected by gravity, can cause the formation of vortex.
The vortex shows a balance between the force of gravity and the inertia force.
3. Power Number
Power Numbers (Po) shows the ratio between the power produced by the flow and the inertia
force. Pressure changes due to flow distribution on the stirrer surface can be integrated
resulting in total torque and stirring speed. The power number is declared as:
… (5)
dengan Po = Power number, N = Impeller rotating speed, dan ρ = fluid density. Power used
is effective power, that is:
Peff = V.I – Vo.Io … (6)
The correlation between the Power numbers with Reynold and Fraude is expressed in the
following equations:
For system without baffle : Po = a Reb Fr
c
For system with baffle : Po = a Reb
where a, b, c = experimental constants. The equation can be dilinearkan with natural
logarithm making it easier to calculate.
B.3. Graph Making
The mixing time correlation curve and stirring flow are made by passing data ln (N.t) to ln
(NRe). The power demand correlation curve to the stirring flow is the ln (NPo) to ln (NRe),
whereas the optimum condition is the intercept point between graph N to t and P to t.
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 17
APPENDIX C
LITERATURE DATA
C.1. Water Density Data at Various Temperatures
Source: Perry’s Chemical Engineers’ Handbook
INSTRUCTIONAL LABORATORY CHEMICAL ENGINEERING DEPT.
FTI - ITB
STIRRED-TANK MODULE (TGK)
TGK – 2016/PW 18
APPENDIX D
JOB SAFETY ANALYSIS CONTROL SHEET
Material name Material properties Hazards and Repressive act
Fluid with low viscosity
Water
• Melting point 0 ˚C
• Boiling point 100 ˚C
• Good solvent
• Viscosity (0.86 cP at 26 ˚C)
• Colorless liquid, odorless
• Polar solvent
• General handling of
practicum materials
Accidents that may occur Repressive act
Water spilled Cleaned with mop.
Short-circuiting of electrical appliances. Immediately switch off the appliance, disconnect the
power supply.
Safety equipment
Laboratory coat Google
Stages of Experiment
Preparation Tools and Materials • Ensure that the power source is properly
installed in the agitator and the stirring motor is
mounted either on the support rod.
Experiment • Ensure that the stir bar rod is properly installed
when changing the type of stir bar.
• Make sure the test rack wheel is locked
Post Experiment • Disconnect all current connections on electrical
appliances
• Turn off the multimeter
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