ESPs are used in steel mills for reducing particulate emissions from blast furnaces, basic oxygen
furnaces, and sinter plants.
In a blast furnace, iron ore is reduced to molten iron, commonly called pig iron. Blast furnaces
are large, refractory-lined steel shells. Limestone, iron ore, and coke are charged into the top of
the furnace. The gases produced during the melting process contain carbon monoxide and particulate
matter. Particulate matter is removed from the blast furnace gas by wet ESPs or scrubbers,
so that the gas (CO) can be burned "cleanly" in blast furnace stoves or other processes.
Both plate and tube-type ESPs having water sprays to remove dust from collection electrodes
are commonly used for cleaning blast furnace gas.
Basic oxygen furnaces (BOFs) refine iron from the blast furnace into steel. A BOF is a pearshaped
steel vessel that is lined with refractory brick. The vessel is charged with molten iron
and steel scrap. A water-cooled oxygen lance is lowered into the vessel, where oxygen is
blown to agitate the liquid, add intense heat to the process, and oxidize any impurities still contained in the liquid metal. The hot gases generated during the oxygen blow are approximately
1090 to 1650°C (2000 to 3000°F). These are usually cooled by water sprays located in
the hood and ducting above the BOF. The cooled gases are then sent to an ESP or scrubber to
remove the particulate matter (iron oxide dust). The iron oxide dust can have high resistivity,
making the dust difficult to collect in an ESP. This problem can usually be reduced by conditioning
the flue gas with additional moisture. Plate ESPs that are rapped or sprayed with water
to remove dust from collection plates are commonly installed on BOFs.
In a sinter plant, materials such as flue dusts, iron ore fines (small particles), coke fines, mill
scale (waste that occurs from various processing steps), and small scrap are converted into a
high-quality blast furnace feed. These materials are first fed onto a traveling grate. The bed of
materials is ignited by burning gas in burners located at the inlet of the traveling grate. As the
bed moves along the traveling grate, air is pulled down through the bed to burn it, forming a
fused, porous, red-hot sinter. The resulting gases are usually sent to an electrostatic precipitator
to remove any particulate matter. If oily scrap is used as a feed material, care must be taken
to prevent ESP collection plates from being coated with tarry particulate matter. Controlling
the amount of oily mill scale and small scrap processed in the sinter plant can help alleviate
this problem. Plate ESPs are commonly used in sinter plants.
furnaces, and sinter plants.
In a blast furnace, iron ore is reduced to molten iron, commonly called pig iron. Blast furnaces
are large, refractory-lined steel shells. Limestone, iron ore, and coke are charged into the top of
the furnace. The gases produced during the melting process contain carbon monoxide and particulate
matter. Particulate matter is removed from the blast furnace gas by wet ESPs or scrubbers,
so that the gas (CO) can be burned "cleanly" in blast furnace stoves or other processes.
Both plate and tube-type ESPs having water sprays to remove dust from collection electrodes
are commonly used for cleaning blast furnace gas.
Basic oxygen furnaces (BOFs) refine iron from the blast furnace into steel. A BOF is a pearshaped
steel vessel that is lined with refractory brick. The vessel is charged with molten iron
and steel scrap. A water-cooled oxygen lance is lowered into the vessel, where oxygen is
blown to agitate the liquid, add intense heat to the process, and oxidize any impurities still contained in the liquid metal. The hot gases generated during the oxygen blow are approximately
1090 to 1650°C (2000 to 3000°F). These are usually cooled by water sprays located in
the hood and ducting above the BOF. The cooled gases are then sent to an ESP or scrubber to
remove the particulate matter (iron oxide dust). The iron oxide dust can have high resistivity,
making the dust difficult to collect in an ESP. This problem can usually be reduced by conditioning
the flue gas with additional moisture. Plate ESPs that are rapped or sprayed with water
to remove dust from collection plates are commonly installed on BOFs.
In a sinter plant, materials such as flue dusts, iron ore fines (small particles), coke fines, mill
scale (waste that occurs from various processing steps), and small scrap are converted into a
high-quality blast furnace feed. These materials are first fed onto a traveling grate. The bed of
materials is ignited by burning gas in burners located at the inlet of the traveling grate. As the
bed moves along the traveling grate, air is pulled down through the bed to burn it, forming a
fused, porous, red-hot sinter. The resulting gases are usually sent to an electrostatic precipitator
to remove any particulate matter. If oily scrap is used as a feed material, care must be taken
to prevent ESP collection plates from being coated with tarry particulate matter. Controlling
the amount of oily mill scale and small scrap processed in the sinter plant can help alleviate
this problem. Plate ESPs are commonly used in sinter plants.
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