Dust Catcher Operation Full Video | Blast Furnace | Tech It Eze

Dust Catcher Operation Full Video | Blast Furnace | Tech It Eze
Hi Friends.
Today, We will discuss about Dust catcher
Working principle
Design features
Advantages
Limitations
DUST CONCENTRATION IN RAW GAS
STEAM COIL USED TO AVOID MOISTURE CONDENSATION

A blast furnace gravity dust catcher is a simple, yet effective, device used to capture dust, mainly coarse particles and particulate matter emitted from the blast furnace.
Working principle:
Gases from the blast furnace enter the dust catcher through a duct.
The gases then pass through a chamber where the velocity is reduced, allowing the dust particles to settle due to gravity.
The settled dust is collected in a hopper or container for disposal or recycling.
The cleaned gases exit the dust catcher and are further treated or released into the atmosphere.
Design features:
Chamber shape: Typically a cylindrical chamber with a large volume to slow down the gas flow.
Inlet and outlet: Designed to minimize turbulence and ensure smooth gas flow.
Dust collection hopper: A cone-shaped or cylindrical container to collect the settled dust.
Drainage system: To remove collected dust and prevent build up.
Advantages:
Low maintenance: Simple design with few moving parts.
Low operating cost: No energy required for operation.
High efficiency: Can capture dust particles 40 to 60%.
Compact design: Can be installed in limited spaces.
Limitations:
Limited capacity: Not suitable for high-volume gas flows.
Particle size: Less effective for very fine particles less than 5 microns.
Gas velocity: Requires a relatively low gas velocity to ensure effective dust settling.
Gravity dust catchers are often used in conjunction with other air pollution control devices, such as Wet cyclones, Wet scrubbers, or dry electrostatic precipitators, or bag filter to achieve higher overall efficiency.
DUST CONCENTRATION IN RAW GAS
Blast furnace raw gas dust concentration can vary depending on factors like:
Coal quality: Higher ash content in coal leads to higher dust concentrations.
Coke quality: Coke with higher ash and volatile matter content contributes to higher dust levels.
Furnace operation: Factors like furnace temperature, reducing agent rate and slag composition impact dust generation.
Iron ore quality: Iron ore with higher silica and alumina content can increase dust concentrations.
Typical dust concentrations in blast furnace raw gas:- 10-20 g/Nm³
Dust composition:-
Carbonaceous matter -
Iron oxides -
Silica -
Alumina -
Other oxides and impurities
After passing through a gravity dust catcher, the blast furnace gas dust concentration is typically reduced to 5 to 15 g/Nm³
This represents a significant reduction 40-60% in dust concentration compared to the raw gas.
STEAM COIL USED TO AVOID MOISTURE CONDENSATION
Steam coil used as a heating coil in lower bottom cone of Dust Catcher (outside) to maintain temperature inside the dust catcher, so that condensation of the moisture do not occur, thus reducing the chances of dust jam in the side wall. Insulation of Dust Catcher wall also helps maintaining inside temperature.

Steam coil used as a heating coil in lower bottom cone of Dust Catcher outside to maintain temperature inside the dust catcher, so that condensation of the moisture do not occur, thus reducing the chances of dust jam in the side wall. Insulation of Dust Catcher wall also helps maintaining inside temperature.

Thermocouples used for measuring dust & gas temperature
In a blast furnace gravity dust catcher, the dust level and thermocouple readings are crucial parameters to monitor. Here's what they indicate:
Dust Level:
Measures the accumulation of dust in the catcher.
Indicates when the dust needs to be removed e.g., via hopper discharge.
Helps maintain optimal dust catcher performance.
Excessive dust levels can lead to: - Reduced gas flow - Increased pressure drop - Decreased dust separation efficiency - Potential damage to downstream equipment