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Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
Lecture2  Wood, Charcoal And Peat @ Www.07 Met.Tk
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Lecture2 Wood, Charcoal And Peat @ Www.07 Met.Tk

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  • 1. Wood, Charcoal and Peat Fuel and Furnaces 19/09/2008
  • 2. Wood
    • It is domestic fuel, used in countries where forests are abundant
    • Main components are cellulose and lignin, which are compounds of Carbon, Hydrogen and Oxygen.
    • Minor components are resin and waxes
    • Water which is non-inflammable is present up to 25- 50% (fresh) and 10-15% (dry)
    • Ash content is < 1% but due to high oxygen content (up to 45%), its calorific value is very low (4000-5000Kcal/Kg)
  • 3. Proximate Analysis
    • Cellulose = 50%
    • Lignin = 30%
    • Resin + wax= 2%
    • Moisture = 15%
    • Ash = 0.5%
    • Water solubles = 2.5%
    • C.V = 4500Kcal/Kg
    • Density = 650 kg/m 3
  • 4. Ultimate Analysis
    • Ultimate analysis of typical air dries hard wood is as follow:
    • Carbon = 50%
    • Oxygen = 44%
    • Hydrogen = 6%
  • 5. Burning Characteristics of Wood
    • Easily ignitable
    • Smaller pieces more efficiently combustible as compared with large pieces.
    • Wood fines e.g sawdust burns quite easily and readily.
    • It can be made into binder less briquettes at high pressure
    • It burns with large non-smoky flames when burnt in excess air.
    • Ash formed on surfaces of large pieces prevent its further burning
  • 6. Uses of Wood
    • Domestic fuels in many areas of the world
    • Furniture making
    • To produce wood charcoal by its carbonization or destructive distillation
    • To produce producer gas by its gasification
    • Heating of homes in winter
    • Making tools for different applications
    • As fueling for steam engines, turbines to generate electricity
    • http://www.fao.org/docrep/X5328e/x5328e05.jpg
  • 7. Wood Charcoal
    • It is simply charcoal made by the carbonization (destructive distillation i.e heating in the absence of air) of wood at 600 o C
    • Stages of Carbonization of Wood:
    • When temperature is reached at 100-120 o C, the moisture of the wood is expelled first.
    • At 275 o C, initial decomposition of wood takes place resulting in the formation of little distillate gas containing acetic acid and water.
    • At 350 o C active distillation takes place till the process is exothermic producing liquid products (like acetic acid, methyl alcohol, pyroligneous acids and tar etc).
    • Gaseous products contain carbon monoxide, carbon dioxide, Nitrogen, Hydrogen and Hydrocarbons etc
    • From 350-600 o C, slow evolution of residual volatile matters (i.e gases) from the wood/charcoal left in the 3 rd stage
  • 8. Swedish Charcoal Formation
    • A - Fuel wood
    • B - Carbonization zone
    • C - Charcoal zone
    • http://www.fao.org/docrep/X5328e/x5328e07.htm#TopOfPage
  • 9. Products in Wood Carbonization
    • Solid product left after carbonization is charcoal.
    • Hot gases are cooled to separate wood gas and liquid into two layers.
    • Upper layer is pyroliginous acid (aqueous solution of acetone, methyl alcohol, acetone and wood spirit ) and lower is wood tar.
    • Wood tar can be fractionated into many chemicals. It is used as supplementary plant fuel.
    • Matured dense wood gives dense charcoal on carbonization
    • Yield per ton (1000 kg) of air dry wood
    • Acetic acid =50 kg Methanol=16 kg
    • Acetone and methyl acetone =8 kg
    • Soluble tars=190 kg
    • Insoluble tars=50 kg
  • 10. Carbonization Scheme
    • Carbonization of wood is carried out in:
    • 1-Open pits & Kilns (located in forests)
    • 2- Retorts (Factories)
    • In open pits, wood is burned in large heaps with restricted air. Yield of charcoal is 20%, have inferior qualities.
    • Kilns have parabolic shape having typical dimensions , radius= 3 meters, height = 2.5 meters and capacity = 30m 3 of stocked wood.
    • See Swedish Charcoal formation kiln.
    • Carbonization time in kilns is from 7-10 days
    • After it kilns are cooled down to get charcoal out of it.
  • 11. Metal Retorts Carbonization
    • It is done at low temperature of 350 o C. These are of four types:
    • Externally fired (heated) batch retorts
    • Externally fired continuous vertical retorts
    • Internally heated batch vertical retorts
    • Internally heated continuous vertical retorts
  • 12. Low Temperature Carbonization Products Properties
    • Charcoal yield is high (35%)
    • Ash content of charcoal is low (< 2.5%)
    • Volatile matter in charcoal is high (15%), hence it can be easily ignited and burns at low rates
    • Heating value of charcoal is high (7500Kcal/Kg)
    • Charcoal produced has high vapor adsorption capacity
  • 13. High Temperature Carbonization
    • It is carried out mainly for the production of town gas beside charcoal.
    • Carbonization temperature is 1000-1200 o C
    • Besides town gas (used for domestic ovens), valuable liquid chemicals like creosote (for wood preservation), turpentine, light & heavy oils are produced .
    • Products characteristics are:
    • Charcoal yield= 25%
    • C.V of charcoal= 8000Kcal/Kg
    • Gas yield= 850 Nm 3 gas/ton dry wood
    • Gross C.V of gas = 3000Kcal/ Nm 3
    • Composition of gas: CO 2 (13%), C m H n Unsaturated hydrocarbons (2%), CO (24%), CH 4 (15%), N 2 (1%), H 2 (45%)
  • 14. Uses Of Charcoal
    • Cooking fuel
    • Charcoal briquettes are widely used for outdoor grilling and barbecues in backyards and on camping trips.
    • In many non-industrialized countries, for instance in Africa , charcoal is used for everyday cooking by a large portion of the population. This is potentially a serious health problem when used indoors since carbon monoxide (CO) is a combustion product.
    • Industrial Fuel
    • Historically, charcoal was used in great quantities for smelting iron in bloomeries and later blast furnaces and finery forges . This use was replaced by coke during the Industrial Revolution .
  • 15. Uses Contd…
    • Automotive fuel
    • In times of scarce petroleum, automobiles and even buses have been converted to burn wood gas (gas mixture containing primarily carbon monoxide ) released by burning charcoal or wood in a wood gas generator .
    • Purification/Filtration
    • The porosity of activated charcoal accounts for its ability to readily adsorb gases and liquids; charcoal is often used to filter water or adsorb odors . Its pharmacological action depends on the same property; it adsorbs the gases of the stomach and intestines , and also liquids and solids (hence its use in the treatment of certain poisonings ). Charcoal filters are used in some types of gas mask to remove poisonous gases from inhaled air. Wood charcoal also to some extent removes coloring material from solutions, but animal charcoal is generally more effective.
  • 16. Composition of Charcoal
    • A typical composition of charcoal is given below:
    • C = 80%
    • O 2 & N 2 = 15%
    • H 2 = 2%
    • Ash = 3%
  • 17. Merits & Demerits of Charcoal
    • Merits:
    • High specific surface area as compared to coal (20 – 200 m 2 )
    • Low ash contents (< 3%)
    • High C.V (7500- 8000 Kcal/Kg)
    • Demerits:
    • Due to poor mechanical strength, it is crushed during operation.
    • It is easily swept away by gases
    • May prevent of proper flow of gases in furnace
  • 18. Wood Gasification
    • Hard wood is gasified in the presence of steam and air to make producer gas. This producer gas can be used as a fuel or for the synthesis of ammonia (by the removal of Hydrogen from it).
    • Gas yield = 1500 Nm 3 /ton of crude wood
    • C.V of wood gas = 1500 Kcal/Nm 3
    • Typical composition of wood gas:
    • CO 2 = 9%
    • CO = 25%
    • H 2 = 15%
    • CH 4 = 3%
    • N 2 = 48%
  • 19. Peat
    • Peat is the first stage in the formation of coal from wood (cellulose). It is the most immature coal. It has been formed by the gradual decaying of vegetable in the moist places.
    • It appears light brown and fibrous at surface of peat deposits.
    • with increase in depth the it become darker and vegetable structure disappears.
  • 20. Composition & Properties of Peat
    • It varies from place to place depending upon:
    • Nature of original vegetables matter
    • Depth in deposit
    • Age
    • Freshly mined peat contain up to 90% water and just 10% solid, it can not be utilized unless air dried to reduce the moisture content to 30% or less.
    • Its heating or C.V values are very much low due to high water content, and is only slightly greater than wood.
  • 21. Peat Contd…
    • Typical composition freshly mined peat
    • Moisture = 85%
    • Volatile matter = 8%
    • Fixed carbon = 4%
    • Ash = 3%
    • C.V = 650Kcal/Kg
    • Typical proximate analysis after sun dried
    • Moisture = 20%
    • Ash = 5%
    • Fixed Carbon = 25%
    • Volatile matter = 50%
    • C.V = 5000 Kcal/Kg
  • 22. Occurrence of Peat
    • Russia has largest peat deposits (60% of world reserve)
    • Besides, it occurs in Germany, Poland, America, Sweden, Norway, Ireland etc.
    • Peat is extracted by hand cutting and also by mechanical excavation method. Air drying of peat may require 40- 50 days
  • 23. Burning Characteristics of Peat
    • Offer low furnace temperature and efficiency due to its low C.V values
    • Have very low bulk density i.e 300 Kg/m 3 (compared to coal having 700 Kg/m3). Its transportation cost is high as it occupy more volume per unit weight also need more storage space.
    • Its friable nature causes appreciable losses on handling prior to its burning.
  • 24. Comparative analysis
    • A comparative analysis of peat charcoal and wood charcoal is given below:
    • % Elements Wood charcoal Peat Charcoal
    • Carbon 85 84
    • Hydrogen 3 2
    • O 2 + N 2 3.5 8
    • Ash 2.5 3
    • Moisture 6 3
    • C.V , Kcal/Kg 7500 7000
  • 25. Gasification of Peat
    • It is gasified in presence of steam and air to produce producer gas. Steam requirement is very low as compared to coal as peat itself contain enough moisture.
    • Gas produced very suitable for gas engines
    • Good quantity of ammonia can be recovered from the gas
    • A typical composition of gas contains:
    • CO 2 = 13%
    • CO = 18%
    • H 2 = 11%
    • CH 4 = 2.5%
    • N 2 = 55.5%
    • C.V of gas = 1000Kcal/Nm 3
    • Gas yield = 2500 Nm 3 /ton peat
  • 26. Uses of Peat
    • Used as domestic fuel in Great Britain
    • Steam and Power generation (USSR)
    • Gasified to produce producer gas and carbonized to get peat charcoal and by-products
    • Fertilizer or making fertilizers
    • Bedding/ litter for livestock
    • Horticulture
    • Electricity
  • 27. Other Non-Fossil Domestic Solid Fuels
    • These solid fuels includes:
    • Wood waste
    • Bagasse
    • Agricultural/ Vegetable wastes
    • Cattle dungs
    • Dry leaves/ twinges collected from forests
  • 28. Thanks for your Attention Questions are Welcomed ?

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