Date:03/06/2022 DAPCE 3171307

Definitions of Terms

1. Vortex Finder:

   A vortex finder is a component used in cyclone separators. It is an extended tube-like structure located at the top of the cyclone, designed to collect the cleaned gas phase and guide it out of the cyclone while allowing the separated particles to settle downward.

2. Migration Velocity:

   Migration velocity is the velocity at which particles suspended in a gas stream move toward the collection surface (such as filter media) under the influence of an external force, usually an electric field or gravity. It is a critical parameter in electrostatic precipitation.

3. Air to Cloth Ratio:

   The air to cloth ratio (ACR) is a parameter that defines the amount of gas volume passing through a unit area of filter cloth in a baghouse or filtration system. It is calculated by dividing the gas flow rate by the total filter cloth area. It affects filtration efficiency and pressure drop.

4. Liquid to Gas Ratio:

   The liquid to gas ratio (L/G ratio) is the ratio of the mass of liquid (usually water) to the mass of gas (often air) in a scrubber or absorption system. It indicates the amount of liquid available to interact with the gas for pollutant removal or absorption.

Comparison: Adsorption vs. Absorption Tower

Aspect	Adsorption Tower	Absorption Tower
Process Definition	Adsorption is the process of capturing and binding gases, vapors, or solutes on the surface of a solid material, known as an adsorbent.	Absorption is the process of dissolving a gas or vapor into a liquid, resulting in the transfer of the gaseous component into the liquid phase.
Phase Interaction	Gas phase pollutants are removed from the gas stream by sticking to the solid surface of the adsorbent.	Gas phase pollutants are absorbed into the liquid phase, forming a solution.
Medium Used	Adsorbent material (solid) is used to capture pollutants.	Liquid solvent is used to absorb pollutants.
Equilibrium	Adsorption reaches equilibrium when the adsorbent surface becomes saturated with adsorbed molecules.	Absorption reaches equilibrium when the concentration of the gaseous component in the liquid phase reaches a maximum level.
Regeneration	Adsorbent can be regenerated by desorbing the captured pollutants using heat or other methods.	Absorption solutions can be regenerated by various methods like distillation or chemical reactions.
Example Application	Removal of volatile organic compounds (VOCs) from industrial air streams using activated carbon.	Removal of acid gases (e.g., SO2, HCl) from flue gases using a scrubbing liquid.

Comparison: ID Fan vs. FD Fan

Aspect	ID Fan	FD Fan
Function	Induced Draft (ID) fans are used to create a negative pressure (suction) in the furnace or boiler to facilitate the flow of flue gases through the system.	Forced Draft (FD) fans are used to deliver fresh air or forced air into the combustion chamber of the furnace or boiler, helping in combustion.
Location	ID fans are typically installed on the outlet side of the system, pulling flue gases out.	FD fans are usually positioned on the inlet side, pushing air into the system.
Pressure	ID fans create a negative pressure or suction, helping in drawing flue gases through the system.	FD fans create a positive pressure, pushing air into the combustion chamber.
Applications	Commonly used in boilers, furnaces, and industrial processes to maintain proper draft and ensure efficient combustion.	Used in heating systems, power plants, and industrial processes to ensure adequate air supply for combustion.
Flow Control	ID fans help control the flow of flue gases, maintaining proper draft and preventing backflow.	FD fans control the flow of fresh air into the combustion chamber, affecting combustion efficiency.
Effect on Efficiency	The efficiency of ID fans impacts the ability to remove flue gases efficiently, affecting combustion performance.	FD fans impact combustion air supply, which affects combustion efficiency and overall system performance.

Auxiliary Equipment and Explanation

Auxiliary Equipment	Explanation
Cyclone Separator	Explanation: A cyclone separator is a device designed to remove particulates from a gas or liquid stream using centrifugal force. It operates based on the principle of creating a vortex that separates heavier particles from the gas stream. How It Works: The gas enters the cyclone tangentially, creating a swirling motion. Due to centrifugal force, heavier particles are thrown outward and collected at the cyclone's walls, falling into a collection hopper. Applications: Cyclone separators are commonly used as pre-filters to remove large particles before the gas stream enters more advanced filtration systems. Advantages: Simple design, low maintenance, can handle high gas flow rates, and effective for larger particles. Disadvantages: Less efficient for smaller particles, limited removal efficiency for fine particulates.
Electrostatic Precipitator (ESP)	Explanation: An ESP is a device that uses electrical charges to remove particulates and aerosols from gas streams. It employs the principle of charging particles, causing them to adhere to collector plates or electrodes. How It Works: Gas passes through an ionization section where particles receive an electric charge. Charged particles then migrate towards oppositely charged plates or electrodes, where they are collected and removed. Applications: ESPs are widely used in power plants, cement industries, and other heavy industrial processes to control particulate emissions. Advantages: High removal efficiency for a wide range of particle sizes, suitable for high gas flow rates. Disadvantages: Complex design, maintenance-intensive, sensitive to changes in gas composition.

Types of Fans with Sketches

Type of Fan	Sketch
Axial Fan
Centrifugal Fan
Radial Fan
Mixed Flow Fan
Axial-Flow Roof Ventilator

Various Types of Fans

• Axial Fans: These fans move air parallel to the fan's axis and are commonly used for ventilation and cooling.
• Centrifugal Fans: Also known as blower fans, they move air perpendicular to the fan's axis and are used for higher-pressure applications.
• Radial Fans: Similar to centrifugal fans, these have curved blades and are suitable for high-pressure systems.
• Axial-Flow Roof Ventilators: Specialized axial fans designed for roof ventilation to remove hot air from enclosed spaces.
• Inline Fans: Compact units installed within ductwork to boost airflow in confined spaces.
• Crossflow Fans: These fans create a wide, uniform airflow, commonly used in applications like air conditioning units.
• Propeller Fans: Simple axial fans with fewer blades, often used for moving large volumes of air at low pressures.
• Centrifugal Roof Ventilators: Designed for commercial and industrial buildings to exhaust air from enclosed spaces.
• Mixed-Flow Fans: Combining characteristics of axial and centrifugal fans, they offer higher efficiency and pressure capabilities.
• Radial-Tip Fans: These fans have blades with curved tips and are suitable for handling dusty or abrasive air streams.
• Backward-Curved Fans: Efficient and quieter centrifugal fans with blades curved away from the direction of rotation.
• Forward-Curved Fans: Centrifugal fans with blades curved towards the direction of rotation, often used in clean air applications.
• Mixed-Flow Roof Ventilators: Combining axial and centrifugal fan characteristics, they are suitable for various commercial applications.

Duct System and Basic Principles in Duct Design

Duct System: A duct system is a network of conduits or channels designed to carry air, gases, or liquids from one location to another. It is an essential component of HVAC (Heating, Ventilation, and Air Conditioning) systems, as well as various industrial applications.

Basic Principles in Duct Design:

• 1. Airflow Requirements: Determine the required airflow rate for the specific application, ensuring proper ventilation, cooling, or heating.
• 2. Pressure Drop: Minimize pressure drop along the duct system by selecting appropriate duct sizes, shapes, and layouts. Lower pressure drop enhances system efficiency.
• 3. Air Velocity: Maintain suitable air velocities within ducts to prevent issues like excessive noise, erosion, and accumulation of dust or debris.
• 4. Duct Material: Choose appropriate duct materials based on factors such as temperature, corrosion resistance, and insulation requirements.
• 5. Duct Sizing: Calculate the optimal duct size considering factors like airflow rate, velocity, pressure drop, and available space.
• 6. Duct Shape: Select duct shapes (round, rectangular, or oval) based on the specific requirements of the system, available space, and airflow distribution needs.
• 7. Duct Layout: Plan the layout of ducts, branches, and fittings to ensure efficient airflow distribution and minimize disruptions to surrounding structures.
• 8. Air Distribution: Design duct systems that provide uniform air distribution throughout the conditioned space, avoiding uneven temperature variations.
• 9. Insulation: Apply appropriate insulation materials to ducts in conditioned spaces to prevent heat loss or gain and maintain energy efficiency.
• 10. Noise Control: Incorporate design features to minimize noise transmission through ducts, such as using acoustic insulation and avoiding sharp bends.

Short Note on Hood

A hood is an essential component in an industrial ventilation system that captures and controls contaminants, fumes, dust, or gases generated during various industrial processes. It is designed to ensure the safety of workers, protect the environment, and maintain indoor air quality. Hoods are strategically placed at or near the source of emission to efficiently collect and contain the pollutants before they disperse into the surrounding air.

Key Functions of Hoods:

• Containment: Hoods effectively contain the pollutants at the source, preventing their release into the work environment.
• Capture Efficiency: Well-designed hoods maximize the capture of pollutants, minimizing exposure to workers.
• Directional Control: Hoods direct the flow of contaminants away from workers, equipment, and critical areas.
• Airflow Control: They regulate the airflow to ensure pollutants are drawn into the hood and properly exhausted.
• Compatibility: Hoods are tailored to the specific process and pollutant characteristics, optimizing their effectiveness.
• Connection to Exhaust System: Hoods are connected to an exhaust system that transports the captured pollutants to filtration or treatment devices.

Types of Hoods:

There are various types of hoods designed for different applications:

• Local Exhaust Hoods: Placed directly at the emission source to capture contaminants immediately.
• Canopy Hoods: Used to capture pollutants generated by processes like cooking or chemical reactions.
• Ductless Hoods: Incorporate filtration mechanisms to remove pollutants before releasing air back into the environment.
• Slot Hoods: Designed as thin, horizontal openings to efficiently capture contaminants.
• Enclosure Hoods: Completely enclose the process area to prevent pollutants from escaping.

Hoods play a crucial role in maintaining a safe and healthy work environment by preventing the dispersion of harmful substances and contaminants. Proper design, placement, and maintenance of hoods are vital for effective industrial ventilation.

Operation and Maintenance of Bag Filter

Operation:

A bag filter, also known as a fabric filter, is an air pollution control device used to remove particulate matter from gas streams. It operates by passing the gas through a series of fabric filter bags, where particles are captured on the surface or within the fabric media. Here's how it works:

1. Filtration: Dirty gas containing particulates enters the bag filter system.
2. Particle Capture: The gas flows through the fabric filter bags, and particulates are captured on the surface or within the filter media.
3. Clean Gas Outlet: Filtered gas exits the system through the clean gas outlet.
4. Cleaning Cycle: Over time, captured particles accumulate on the filter bags, leading to increased pressure drop. To maintain efficiency, the bags are periodically cleaned through techniques like reverse air, pulse jet, or shaker mechanisms.

Maintenance Issues:

• Bag Cleaning: Regular cleaning of filter bags is essential to prevent excessive pressure drop and maintain filtration efficiency. The choice of cleaning method depends on the system's design and the type of pollutants.
• Bag Replacement: Over time, filter bags degrade due to wear and tear from particle impacts and cleaning cycles. Regular replacement ensures effective filtration.
• Leakage Detection: Periodic inspections are necessary to identify and repair any leaks or damage in the filter system that could lead to bypassing of particulates.
• Monitoring Pressure Drop: Monitoring pressure drop across the filter helps determine when cleaning or replacement is required, optimizing efficiency and energy consumption.
• Material Compatibility: Bag material must be compatible with the gas composition to avoid degradation or corrosion. Proper selection ensures longer bag life.
• Sealing and Gasketing: Ensuring proper sealing and gasketing throughout the system prevents air leaks that can affect filtration efficiency.
• Instrument Calibration: Regular calibration of pressure sensors and control instruments helps maintain accurate pressure drop readings and control of the cleaning cycles.
• Emergency Shutdown Plan: Having a shutdown plan in place for maintenance activities prevents uncontrolled release of particulates during maintenance.

Proper operation and diligent maintenance are crucial for the bag filter's performance and longevity, ensuring effective particulate removal and compliance with environmental regulations.

Operation and Maintenance of Cyclone Separator

Operation:

A cyclone separator is a simple and widely used device for removing particulate matter from gas streams through centrifugal force. It operates based on the principles of inertia and pressure difference. Here's how it works:

1. Inlet: Gas with particulates enters the cyclone through the inlet.
2. Centrifugal Force: The gas swirls in a spiral motion, creating centrifugal force that pushes heavier particles toward the cyclone's walls.
3. Particle Separation: Due to centrifugal force, particles move outward and downward, eventually falling into the collection hopper at the bottom of the cyclone.
4. Clean Gas Outlet: The cleaned gas exits the cyclone through the upper outlet.

Maintenance Issues:

• Regular Inspection: Periodic inspections are necessary to ensure the cyclone's structural integrity and identify any wear, corrosion, or damage.
• Collection Hopper: The collection hopper needs to be emptied regularly to prevent excessive particle buildup, which can lead to reduced efficiency and increased pressure drop.
• Pressure Drop Monitoring: Monitoring pressure drop across the cyclone helps indicate when maintenance is required and if there are any blockages.
• Wear Protection: In cases of abrasive particles, wear-resistant linings or coatings can be used to extend the cyclone's lifespan.
• Efficiency Testing: Periodic testing of the cyclone's efficiency ensures it is performing as expected and meeting required emission standards.
• Sealing and Gaskets: Proper sealing and gasketing are essential to prevent leaks that could affect the cyclone's performance.
• Anti-Static Measures: In applications with explosive materials, anti-static measures may be needed to prevent static buildup and potential hazards.
• Emergency Shutdown Plan: Having a plan in place for maintenance activities prevents unintended releases of particulates during maintenance.
• Component Replacement: Over time, parts like the vortex finder and dip tube may need replacement due to wear or corrosion.

Proper operation and maintenance are crucial to the cyclone separator's efficiency in removing particulates and ensuring compliance with environmental regulations.

Short Note on Spray Tower

A spray tower, also known as a spray chamber or spray scrubber, is an air pollution control device used to remove pollutants from a gas stream by introducing a liquid spray. It operates on the principle of contact between the gas and the liquid spray, which results in the absorption or dissolution of contaminants into the liquid phase. Spray towers are commonly used for controlling emissions of gases and particulate matter in various industrial processes.

Key Features and Operation:

• Spray Nozzles: The tower is equipped with spray nozzles that disperse a fine liquid mist into the gas stream.
• Gas-Liquid Contact: As the gas and liquid come into contact, pollutants are absorbed or react with the liquid, leading to their removal from the gas phase.
• Absorption and Scrubbing: Spray towers are effective for removing acidic gases, such as sulfur dioxide (SO2), as well as particulate matter and volatile organic compounds (VOCs).
• Scrubbing Liquids: The choice of liquid depends on the contaminants being targeted. Water, chemicals, or alkali solutions may be used as scrubbing liquids.
• Counterflow or Crossflow: Spray towers can have a counterflow or crossflow configuration, depending on the direction of gas and liquid flow.
• Demisting Section: A demisting or mist eliminator section is often included to remove liquid droplets from the gas before it exits the tower.

Applications:

Spray towers are utilized in various industries for emissions control, such as:

• Removal of sulfur dioxide (SO2) and acid gases from flue gases in power plants and industrial boilers.
• Control of particulate matter in cement and mineral processing plants.
• Removal of volatile organic compounds (VOCs) and odorous compounds from chemical and petrochemical processes.
• Control of fumes and dust from metal smelting and refining operations.

While effective, the design and operation of spray towers require careful consideration of factors such as gas-liquid contact time, liquid flow rate, spray nozzle design, and overall system configuration. Regular maintenance and monitoring are essential to ensure optimal performance and compliance with environmental regulations.

Short Note on Spray Tower

A spray tower, also known as a spray chamber or spray scrubber, is an air pollution control device used to remove pollutants from a gas stream by introducing a liquid spray. It operates on the principle of contact between the gas and the liquid spray, which results in the absorption or dissolution of contaminants into the liquid phase. Spray towers are commonly used for controlling emissions of gases and particulate matter in various industrial processes.

Key Features and Operation:

• Spray Nozzles: The tower is equipped with spray nozzles that disperse a fine liquid mist into the gas stream.
• Gas-Liquid Contact: As the gas and liquid come into contact, pollutants are absorbed or react with the liquid, leading to their removal from the gas phase.
• Absorption and Scrubbing: Spray towers are effective for removing acidic gases, such as sulfur dioxide (SO2), as well as particulate matter and volatile organic compounds (VOCs).
• Scrubbing Liquids: The choice of liquid depends on the contaminants being targeted. Water, chemicals, or alkali solutions may be used as scrubbing liquids.
• Counterflow or Crossflow: Spray towers can have a counterflow or crossflow configuration, depending on the direction of gas and liquid flow.
• Demisting Section: A demisting or mist eliminator section is often included to remove liquid droplets from the gas before it exits the tower.

Applications:

Spray towers are utilized in various industries for emissions control, such as:

• Removal of sulfur dioxide (SO2) and acid gases from flue gases in power plants and industrial boilers.
• Control of particulate matter in cement and mineral processing plants.
• Removal of volatile organic compounds (VOCs) and odorous compounds from chemical and petrochemical processes.
• Control of fumes and dust from metal smelting and refining operations.

While effective, the design and operation of spray towers require careful consideration of factors such as gas-liquid contact time, liquid flow rate, spray nozzle design, and overall system configuration. Regular maintenance and monitoring are essential to ensure optimal performance and compliance with environmental regulations.