Blast furnace gas

Blast furnace gas

1. BLAST FURNACE GAS Presented BY M.Abdullah I rshad DDP-SP13-BEC-032 Shahzaib chuhdary DDP-SP13-BEC-085 Zagham Nadeem DDP-SP13-BEC-097 M.Ajmal DDP-SP13-BEC-107

2. 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.

3. 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.

4. 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

5. Oxygen in the air reacts with coke to give carbon dioxide: C (s ) + O 2(g)  CO 2(g) The limestone breaks down to form carbon dioxide: CaCO 3(s )  CO 2 (g) + CaO (s) Carbon dioxide produced in 1 + 2 react with more coke to produce carbon monoxide: CO 2(g ) + C (s)  2CO (g) Step Involved In Blast Furnace

6. The carbon monoxide reduces the iron in the ore to give molten iron : 3CO (g ) + Fe 2 O 3(s)  2Fe (l) + 3CO 2(g ) The limestone from 2, reacts with the sand to form slag (calcium silicate ): CaO (s ) + SiO (s)  CaSiO 3(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

7. 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

8. 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

9. Properties of blast furnace

10. Ignition Temperature It’s ignition temperature value range b/w 670 to 690 almost. Higher than many other fuel gases.

11. Calorific value Its calorific value is about 800-900 Contain more co, less H 2 and has a much lower calorific value than coke oven gas and other fuel.

12. 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

13. Density Its density is about 1.3 to1.4 (kg/Nm 3 ) Slightly heavier than air (1.28 ( kg/Nm 3 ) Other properties colourless , odourless and tasteless in nature

14. 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/cm 2 10-25gms of dust/Nm 3 Diameter of dust particles 0.1 micron to 5mm.

15. 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

16. Process

17. 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

18. 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.

19. 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 G as is drawn through the tube at stated rate for two minutes Carbon monoxide causes the colour of the yellow to dark brown to blue

20. Dark blue means concentration of about 1000 ppm of carbon monoxide in atmosphere

21. 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.

22. Uses of B.F Gas Blast Furnace stoves Soaking pits Reheating Furnace Billet heating Foundrary ovens Annealing furnaces Boilers Coke oven underfiring