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22CHE04 – Air Pollution Control

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Syllabus Copy

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Tutorial Plan

Event

CO1

CO2

CO3

CO4

CO5

Tutorial 1

100

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--

--

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Tutorial 2

50

50

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Tutorial 3

--

50

50

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Tutorial 4

--

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50

50

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Tutorial 5

--

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50

50

Tutorial 6

20

20

20

20

20

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S.No.

Course Outcomes

Topics

TL Methods

  1.  

CO1

Categorize air pollutants into primary (SO2, CO) and secondary (O3, PAN) types with industrial examples

Online Quiz

  1.  

CO2*

Gaussian plume modeling software using open-source software like ALOHA, SCREEN3 etc.

ICT usage/Activity based learning

  1.  

CO3*

Thermal power plant with onsite observations

Field Visit

  1.  

CO4*

Design and development of ESPs and Baghouses based on expert case studies

Expert Lecture

  1.  

CO5

Present case studies on drone-based pollution monitoring

Seminar

TL Method Plan

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Plume Modeling Tools – Planned CO2

ALOHA

AERMOD

SCREEN3

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Industrial Visit – Planned – CO3

Resource Person:

Mr.Nagarajan Ramachandran,

Associate President – Process Safety & Energy Transition, Chola MS Risk Services Limited, Chennai

Expert Lecture – Planned – CO4

Visit to Mettur Thermal Power Plant, Mettur

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Incinerator – Working and Construction

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Limited to larger particle size in the range of 40 to 60 µm

Gravity Settling Chamber

Types:

    • Simple expansion chamber
    • Multi tray settling
    • Baffled chamber

Several horizontal collection plates (N) to improve the collection efficiency of small particles (as small as 15mm in dia)

Howard settling

chamber

Horizontal settling chamber

The physical description of a gravity settler includes

  1. length,
  2. width,
  3. height,
  4. number of shelves,
  5. ancillary equipment – inlet and outlet, ducts, cleaning mechanisms, hoppers, etc.

Baffled chamber

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Gravity Settling Chamber – Operation and Maintenance

Failures in GSC

  • Excessive flow rates 🡺 corrosion/erosion or vibration
  • Recommended maintenance

Regular inspection –

        • Vibratory disturbance
        • Excessive pressure drop
        • Decreased efficiency

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Cyclone Separator

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Cyclone Separator – Operation and Maintenance

Operating Variables

    • Gas variables: temperature, pressure, and composition
    • Dust characteristics: particle size, size distribution, shape, density and concentration

Effect of Variables on Performance:

    • Gas density decreases and viscosity increases with higher temperature.
    • Gas density is negligible compared to particle density → no direct effect on efficiency.
    • Higher temperature → higher inlet velocity → increases particle velocity toward wall.
    • Higher viscosity → decreases particle velocity toward wall.
    • Net effect: Between 40–700 °F → efficiency is constant.
    • Above 1000 °F → viscosity dominates → efficiency decreases.
    • Gas composition can affect viscosity and density.

Airtight Operation Requirement

    • Cyclone dust collectors must be airtight.
    • Gaskets should be used to seal flange gaps.
    • Small leaks can cause entrainment and dust escape

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Baghouse Filters – Working

General Features

    • One of the oldest, simplest, and most efficient methods for removing particulates from gas streams.
    • Collect particles as small as 0.1 μm effectively; removes many as small as 0.01 μm.
    • Basic construction: woven or felted fabric through which dust-laden gases are forced.

Filtration Mechanisms

    • Woven fabrics: Dust forms cake → acts as sieving mechanism.
    • Felted fabrics: Minimal dust cake → collection via inertial forces, impingement, etc.

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Baghouse Filters – Operation and Maintenance

Baghouse Cleaning Methods

Particle removal methods include:

    • Shaking the bags
    • Blowing a jet of air from a reciprocating manifold
    • Pulse jet cleaning → rapidly expanding the bag with a short pulse of compressed air

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Electrostatic Precipitators – Working

Charging Mechanism

Process Steps

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Wet Electrostatic Precipitators – Working

Advantages of Wet ESP:

  • Preconditioning step, where inlet sprays in the entry section
  • A wetted collection surface to continuously flush away collected materials.
  • Low energy consumption
  • No dust resistivity problems
  • Efficient removal of fine particles

Disadvantages of the Wet ESP:

  1. Low gas absorption efficiency
  2. Sensitivity to changes in flow rate
  3. Dust collection is wet