Solid fuels

What are solid fuels?

Solid fuel is the various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion.

The solid fuels find little practical application at present because of the problems in handling the fuel as well as in disposing of, the solid residue or ash after combustion. 

Solid fuels compared to gaseous and liquid fuels, solid fuels are quite difficult to handle and storage and feeding are quite cumbersome.

Solid fuels are categories by following below :

• Biomass ( 5 C and 37 P )
• Charcoal (27 P )
• Coal (13 C and 64 P )
• Oil shale ( 7 C and 12 P )
• Peat ( 2 C and 4 P )
• Wood fuel ( 1 C and 9 P ) 

Now we can see all of the above in details :

Wood fuel :

Content of wood :

• Cellulose 
• Lignin 
• Resins 
• Inorganic material 
• Water ( 25 - 60 % )

Advantages of wood :

• Burns readily
• Soot and ash produced is small
• Ash is reused 
• Easily available 
• Suitable calorific value for domestic use 

Disadvantages of wood :

• A high percentage of water decreases the calorific value 

Peat :

Content of peat :

• Volatile matter ( 10.4 % )
• Fixed carbon ( 4.6 % )
• Moisture ( 85 % )

Advantages of peat :

• Used as fertilizer
• As for packing material 
• As boiler fuel in the form of briquettes 

Disadvantages of peat :

• High water content 
• Burns slowly 
• Low calorific value 
• Not economical 

Coal :

Content of coal :

• Highly complex organic matter 
• Varying quantity of water 
• Nitrogen ( 0.75 % to 1.75 % )
• Sulpher

There are different grades of coal :

• Anthracite ( 86-88 % )
• Bituminous ( 78-66 % )
• Sub-bituminous coal or black lignite 
• Pulverised coal  

Biomass :

Content of biomass :

• Lignin ( Phenolics 26 % )
• Cellulose ( Glucose 44 % )
• Hemicellulose ( Xylose 30 % )

Charcoal :

Content of charcoal :

• Fixed carbon 
• Hydrogen 
• Oxygen 
• Nitrogen
• Sulpher 
• Moisture 
• Ash