blast furnace gas
TRANSCRIPT
BLAST FURNACE GAS
Presented BY
M.Abdullah Irshad DDP-SP13-BEC-032
Shahzaib chuhdary DDP-SP13-BEC-085
Zagham Nadeem DDP-SP13-BEC-097
M.Ajmal DDP-SP13-BEC-107
Blast Furnace Gas
It is the by-product of blast furnaces that is
generated when the iron ore is reduced
with coke to produce molten iron.
Blast Furnace It is a tall cylindrical furnace
made of steel.
It is narrow at the top and has
an arrangement for the
introduction of ore and outlet for
gases.
Heated with help of Hot Gases.
The function of a blast
furnace is to reduce and
convert iron oxides into
liquid iron
The blast furnace is a huge,
steel stack lined with
refractory brick.
Purpose Of B.F.G
Oxygen in the air reacts with coke to give carbon dioxide:
C(s) + O 2(g) CO2(g)
The limestone breaks down to form carbon dioxide:
CaCO3(s) CO2 (g) + CaO(s)
Carbon dioxide produced in 1 + 2 react with more coke to
produce carbon monoxide:
CO2(g) + C(s) 2CO(g)
Step Involved In Blast Furnace
The carbon monoxide reduces the iron in the ore to give
molten iron:
3CO(g) + Fe2O3(s) 2Fe(l) + 3CO2(g)
The limestone from 2, reacts with the sand to form slag
(calcium silicate):
CaO(s) + SiO(s) CaSiO3(l)
The excess limestone from the second reaction reacts
with the sand (coming from minerals in iron ore) and
forms calcium silicate (slag)
CaO(s)+SiO(s) --> CaSiO3(l).
Slag and molten iron are drained from the bottom of the
furnace and gas produced exits through holes in the top
of the furnace
Composition Of Blast Furnace Gas
C0 (22-25)%
H2 (4-5)%
CO2 (16-20)%
N2 (51-55)%
O2 (0.2-0.5)%
Little amount of NH3, H2S Almost Nill
Yield Of B.F.G
• About 3 tons of blast furnace gas is
generated for 1 ton of pig iron produced,
the coke rate of furnace being 600-900
kg\ton pig iron
• Volumetric yield of B.F.G is about 2000-
2200 Nm3\ton pig iron
Ignition Temperature
• It’s ignition temperature value range b/w 670 to 690
almost.
• Higher than many other fuel gases.
Calorific value
• Its calorific value is about 800-900
• Contain more co, less H2 and has a much lower calorific
value than coke oven gas and other fuel.
Flame temperature
• The value of flame temperature is about 1450°C.
• Lower as compare to other
fuel gases.
Fuel Flame Temperature
acetylene 3,100 °C
candle 1,000 °C (1,800 °F)
carbon monoxide 2,121 °C
cigarette 400-700 °C (750-1,300 °F )
ethane 1,960 °C
hydrogen 2,660 °C
natural gas 2,770 °C
oxyhydrogen 2,000 °C
propane 2,820 °C
Density
• Its density is about 1.3 to1.4 (kg/Nm3)
• Slightly heavier than air (1.28 (kg/Nm3)
Other properties
• colourless, odourless and tasteless in nature
B.F.gas Processing nd cleaning
• B.F.gass leave the furnace at 125-350°C
• With pressure is about 0.5-1.5 kg/cm2
• 10-25gms of dust/Nm3
• Diameter of dust particles 0.1 micron to 5mm.
• It is very poisonous gas. Due presence of carbon
monoxide. Carbon monoxide is harmful when breathed
because it displaces oxygen in the blood and deprives the
heart, brain, and other vital organs of oxygen. Large
amounts of CO can overcome you in minutes without
warning causing you to lose consciousness and suffocate.
Poison Gas
Characteristics Of Blast Furnace Gas•It has a very low calorific value of 800 to 900 kcal/Nm,
depending upon blast furnace coke rate
•It has got a low theoretical flame temperature
•It has a low rate of flame propagation
•It has a high specific gravity
•It burns with non-luminous flame
Poisonous effect of B.F Gas
• Man inhales B.F gas
• React with hemoglobin form Carboxyhaemoglobin
• Effect Dizziness, headache and shivering
• Prolonged exposure in excess of the gas will kill the man exposed.
Determination of Low C0 concentration In atmosphere
Palladosulphite tubes
• A small tubes is packed with short length of plain white silica gel
followed by a length of gel impregnated with yellow
potassiumpalladosulphite each end of the glass tube is drawn to a
fine point and sealed
• Gas is drawn through the tube at stated rate for two minutes
• Carbon monoxide causes the colour of the yellow to dark brown to
blue
Uses of B.F Gas
• Low calorific value but large quantity of the gas produced
it is one of the most important fuels in an integrating iron
and steel plant.