lab manual for various experiments in chemical engineering

Download Lab manual for various experiments in chemical engineering

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An in-depth guide regarding various undergraduate level experiments in chemical engineering.

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  • Chemical Engineering Department, Birla Institute of Technology & Science Pilani, Pilani Campus

    1

    A LABORATORY MANUAL

    FOR

    Chemical Engineering

    Laboratory I

    Edited By

    Dr Suresh Gupta & Dr Hare Krishna Mohanta

    Department of Chemical Engineering,

    Birla Institute of Technology & Science (BITS), Pilani

    September 2014

  • Chemical Engineering Department, Birla Institute of Technology & Science Pilani, Pilani Campus

    2

    CONTENTS

    CYCLE - I

    S. No. Experiment Page No.

    1. a. Flow through Fluidized Bed (Gas and Water) b. Flow through Packed Bed (Gas and Water)

    3

    2 . a. Losses due to pipe fittings b. Losses due to friction in pipes c. Drag Coefficient determination

    10

    3. a. Bernoullis Theorem verification b. Discharge through venturi, orifice and rotameter c. Flow through tubular pipe

    22

    4. a. Pitot tube experiment (Air and Water) b. Reynolds Apparatus

    34

    5. a. Centrifugal pump characteristics b. Reciprocating pump characteristics

    42

    6. a. Heat Pipe demonstrator b. Thermal Conductivity of solids c. Thermal conductivity of liquids

    52

    7. a. Drop wise and film wise condensation b. Unsteady state heat transfer unit

    61

    8. a. Heat Transfer in agitated vessel b. Fluidized bed heat transfer unit

    76

    9. a. Parallel flow & Counter flow heat exchanger b. Shell and Tube heat exchanger

    83

    10. a. Plate type Heat Exchanger b. Finned tube heat exchanger

    92

    CYCLE - II

    S. No. Experiment Page No.

    11. Stefan-Boltzmann Apparatus

    151

    12. Cross-circulation drying apparatus 110

    13. a. Vapour in air diffusion b. Open pan evaporator

    114

    14. Simple/Differential distillation setup 120

    15. Batch crystallizer 125

    16. a. Steam distillation setup

    b. Vapor liquid equilibrium setup

    128

    17. Two phase flow 136

    18. Mass transfer with chemical reaction 141

    19. Adsorption in packed bed 144

    20. Humidification in wetted wall column 148

  • Chemical Engineering Department, Birla Institute of Technology & Science Pilani, Pilani Campus

    3

    EXPERIMENT NO. 1(a)

    FLOW THROUGH FLUIDIZED BED (AIR & WATER)

    1. Aim Study of hydrodynamic and bed characteristics for flow through fluidized beds.

    2. Objective

    To determine the minimum fluidization velocity experimentally as well as theoretically.

    To study the bed expansion characteristics of the fluidized bed (plot log NRe vs. porosity and pressure drop vs. NRe).

    3. Apparatus Stop watch, graduated cylinders, beakers

    4. Theory When a liquid or a gas is passed at very low velocity up through a bed of solid particles, the

    particles do not move, and the pressure drop is given by the Ergun equation. If the fluid

    velocity is steadily increased, the pressure drop and the drag on individual particles increase,

    and eventually the particles start to move and become suspended in the fluid. The terms

    fluidization and fluidized bed are used to describe the condition of fully suspended particles, since the suspension behaves like a dense fluid.

    Fluidized beds are used extensively in the chemical process industries, particularly for the

    cracking of high-molecular-weight petroleum fractions. Such beds inherently possess

    excellent heat transfer and mixing characteristics. These are devices in which a large surface

    area of contact between a liquid and a gas, or a solid and a gas or liquid is obtained for

    achieving rapid mass and heat transfer and for chemical reactions.

    The fluidized bed is one of the best known contacting methods used in the processing

    industry, for instance in oil refinery plants. Among its chief advantages are that the particles

    are well mixed leading to low temperature gradients, they are suitable for both small and

    large scale operations and they allow continuous processing. There are many well established

    operations that utilize this technology, including cracking and reforming of hydrocarbons,

    coal carbonization and gasification, ore roasting, Fisher-Tropsch synthesis, coking,

    aluminium production, melamine production, and coating preparations. Nowadays, you will

    find fluidized beds used in catalyst regeneration, solid-gas reactors, combustion of coal,

    roasting of ores, drying, and gas adsorption operations. The application of fluidization is also

    well recognized in nuclear engineering as a unit operation for example, in uranium extraction,

    nuclear fuel fabrication, reprocessing of fuel and waste disposal.

    When a fluid is admitted at the bottom of a packed bed of solids at a low flow rate, it passes

    upward through bed without causing any particle motion. If the particles are quite small, flow

    in the channels between the particles will be laminar and the pressure drop across the bed will

    be proportional to the superficial velocity (Vo) and for turbulent situations, pressure drop

    across the bed increase nonlinearly with the increase in the superficial velocity. As the

    velocity is gradually increased, the pressure drop increases, but particles do not move and the

    bed height remains the same. At a certain velocity, the pressure drop across the bed

    counterbalances the force of gravity on the particles or the weight of the bed, and any other

    further increase in velocity causes the particles to move and the true fluidization begins. For a

  • Chemical Engineering Department, Birla Institute of Technology & Science Pilani, Pilani Campus

    4

    high enough fluid velocity, the friction force is large enough to lift the particles. This

    represents the onset of fluidization once the bed is fluidized pressure drop across the bed

    remains constant, but the bed height continues to increase with increasing flow.

    Figure 1 Fluidization regimes

    In order to determine the pressure drop through a fixed bed for any flow condition, the Ergun

    equation (1952) can be used:

    dp is the size of particles (m)

    L is the height of the bed (m)

    is the viscosity of sir (N/m2.s)

    U is the average superficial velocity (m/s)

    is the bed voidage or porosity is the density of air/water (kg/m3) P is the pressure drop across the bed (N/m2)

    The average Reynolds number based on superficial velocity which is given by,

    If the Reynolds number is less than 10 then it is laminar flow and is greater than 2000 it is

    turbulent flow. The rest of the values lie in the transition regime. If the flow rate of air/water

    Q is measured in litres, A is the bed cross-sectional area and U is the superficial velocity in

    m/s, then

  • Chemical Engineering Department, Birla Institute of Technology & Science Pilani, Pilani Campus

    5

    Theoretically at incipient fluidization (the stage in the fluidized bed where the force on the

    solid is enough to balance the weight of the solid material),

    P is in mm of manometer

    The pressure drop at fluidization can also be predicted by the equation,

    p is the particle density (kg/m3)

    is the fluid density (kg/m3) g is the gravitational force (m/s

    2)

    Minimum fluidization velocity

    Umf, the minimum fluidizing velocity, is frequently used in fluid-bed calculations and in

    quantifying one of the particle properties. This parameter is best measured in small-scale

    equipment at ambient conditions. The correlation given below can then be used to back

    calculate dp. This gives a particle size that takes into account effects of size distribution and

    sphericity. The correlation can then be used to estimate Umf at process conditions. If Umf

    cannot be determined experimentally, use the expression below directly.

    Assumption: - Consider the uniform particle size.

    Remf = (1135.7 +0.0408Ar) 0.5

    - 33.7 (Wen and Yu correlation for particles dp> 100 m)

    /Re mffpmf Ud

    23 / gdAr fsfp (Ar is the Archimedes Number)

    For particles of dp < 100 m, Baeyens and Geldart (1977) can be used,

    5. Experimental procedure

    1. The height of the static bed Z1 i.e. when there is no flow of water/air (porosity 1) was noted.

    2. The flow of air/water in the column is started and the flow rates from the rotameter were noted.

    3. The corresponding bed heights and pressure drop values were noted. 4. The flow rates were increased steadily and similar data were collected at different intervals.

    5. 6 to 8 readings of flow rates were varied and reading were taken. 6. Steady state flow rate of water was ensured at each point.

  • Chemical Engineering Department, Birla Institute of Technology & Science Pilani, Pilani Campus

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    6. Observations and calculations

    Particle size = 8 mm

    Porosity = 0.6

    Inside diameter of the column (D) = 0.055m

    Cross-sectional area of fluidized column

    = 0.002375 m

    Density of water (at T0C) = 1000 kg/m3 Viscosity of water (at T

    0C) = 0.798*10

    -3 kg/m-s

    Density of air = 1.1687 kg/m3

    Viscosity of air = 1.8633x10-5

    Pa.s

    Velocity V (m/s) = volumetric flow rate of water / cross section area of column

    Initial height of static bed in the column (Z1)

    Porosity of the fluidized Bed: If Z1 and 1 are the height and porosity of the static bed and Z2

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