Manufactured fuel


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Manufactured fuels slide describes carbonisation of coal and briquetting

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Manufactured fuel

  1. 1. MANUFACTURED FUELS By Alfa Sharma M.Tech (GET), 1st Semester Centre For Green Energy Technology Pondicherry University INDIA-60514
  2. 2. CARBONISATION • The process of converting coal into coke is called as carbonization of coal. • When a coking coal is heated in the absence of air, the porous, hard and strong residue left is called coke. • Coke is white, lustrous, dense porous coherent mass. Depending on the behavior of coal, when heated in the absence of air, the coal is classified into; (i) Non-coking coal which undergoes practically no fusing effect and also called as free burning coal. (ii) Coking coal which gives porous, hard and strong residue after heating in the absence of air. The residue is used for metallurgical purposes and is known as coke. They are quite strong and not crushed under the weight of ore, flux and coal in big furnaces.
  3. 3. Properties of Coke • Hard, Porous, Carbonaceous materials • Three important properties of coke; i)Purity - Ascertained by moisture,ash, sulphur,phosphorus content ii)Strength -By Shatter and Micum test iii)Reactivity -By specified minimum porosity calculation -It is also measured with respect to air,CO2,Steam,Sulphur
  4. 4. CARBONISATION LTC MTC HTC (at600˚C) (at800-1000˚C) (at1000-1400˚C)
  5. 5. Low Temp.Carbonisation(LTC) Generally used for production of soft coke or char or semi coke. High temperature gradient was employed for carbonisation in reasonable time as coal a poor conductor. Normally it is a economical upgradation method of low rank coal like lignite. The major products are semicoke, low temp. liquor,crude low temp.spirit and gas.
  6. 6. Karrick Process Carboniser Flow sheet
  7. 7. LTC(continued)……. Typical yield 600˚C Typical Yields(on dry basis) Semi-coke(clean fuel) 75-80% Tar 9-12% Liquor 5-7% Gas 100-120Nm/tonn
  8. 8. Properties of Gas by LTC • Specific gravity(in reference to air) - 0.6 • Calorific value - 6500Kcal/Nm3 Composition in percentage(%) CO2 4.0 CO 7.0 H2 33.0 N2 7.0 CnHn 4.0 CnH2n+2 45.0
  9. 9. Application of Products by LTC • Semicoke as highly reactive produce smokeless flame ideal for domestic solid fuel. • Also semicoke &char utilized for gasification into fuel or synthesis gas for chemicals and fertilizers industries. • The gas obtained is rich in HC’s(hydrocarbons)&poorer in H2 compared to that obtained by HTC(high temp.carbonisation). • Calorific value is high although yield is low. • Alternate source to biomass used for domestic hearths providing clean fuel concept.
  10. 10. HIGH TEMP.CARBONISATION(HTC) • Commercially practised in coke oven for coke and in gas retorts for gas. • Coke oven is of two types; a. Beehive type (coke completely burnt) b. By-product slot type (coke by product obtained) • Similarly gas retorts are of three types producing coal gas; a.Horizontal type retort b.Intermittant vertical retort c.Continuous vertical retort
  11. 11. (Beehive Coke Oven)
  12. 12. (Horizontal Gas Retorts)
  13. 13. Typical Yields from HTC Products Amount(in %) Coke 78-80 Tar 3.0 Crude benzol 0.8 Ammonium Sulphate 1.0 Coke oven gas 330Nm3 /tonne
  14. 14. Coke Oven gas Composition Constituents Amount(in%) H2 54 CH4 28 CO 7.4 N2 5.6 CO2 2.0 O2 0.4 CnHm 2.6 Gross calorific value =5020Kcal/Nm3 (dry condition) =4450Kcal/Nm3 (wet condition)
  15. 15. Difference between LTC &HTC Characteristics Low Temperature Carbonisation High Temperature Carbonisation 1. Heating temperature 500-7000C 900-1200°C 2. Yield of coke 75−80% 65−75% 3. Volatile matter content 5−15% 1−3% 4. Mechanical strength Poor Good 5. Calorific value 6500−9500 kcal/m3 5400−6000 kcal/m3 6. Quantity of by-product gases 130−150 m3/tone 300−390 m3/tone 7. Coke produced Soft Hard 8. Smoke produced Smokeless Smoky 9. In gas, percentage of (a) Aromatic hydrocarbons (b) Aliphatic hydrocarbons Lower Higher Higher Lower 10. Uses Domestic Metallurgy
  16. 16. BRIQUETTE • A briquette is a block of flammable material used as fuel to start and maintain a fire. • Common types of briquettes are charcoal briquettes and biomass briquettes. Parameter Value Briquette density, t/m³ 1.0-1.2 Heat content, MJ/Kg 19.3-20.5 Ash content, % 0.5-1.5
  17. 17. Briquetting • Briquetting consists in applying pressure to a mass of particles with or without addition of binders& converting to agglomerate. • Main objective is to convert low grade solid fuel to one of higher quality. (Generalised Briquetting Process)
  18. 18. Briquetting of Lignites • Briquetting used because of structural quality & as is obtained as fines during mining. • Briquetting requires no binder & comparatively low pressure suffices compaction of particles. • Some important parameters for briquetting; Particle size 8mm(after crushing from 250mm) Moisture 9-11%(reduced from50-56%) Pressure 1000kg/m³ Optimum temperature 70˚C
  19. 19. Briquetting of Bituminous Coal • Briquetting of fine grade coals like bituminous takes place with binders like coal,tar,pitch,petroleum bitumen . ( Typical Briquetting Process)
  20. 20. Parameters for briquetting:- Size 80%lessthan0.5 mm(coal) 93%less than 0.88mm(pitch binder) Moisture content 2-4% Briquetting pressure 150kg/m³ Optimum temperature 150-160˚C Pitch content(binder) 7-8%
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