Liquid And Gaseous Fuels Are Considered Better Fuels Than The Solid Fuels Because Of The Following Reasons 1c215n

Liquid and gaseous fuels are considered better fuels than the solid fuels because of the following reasons: 1. Liquid and gaseous fuels are easier to handle than solid fuels. 2. Liquid and gaseous fuels can be transported easily through pipelines whereas solid fuels cannot be transports in this way. 3. Liquid and gaseous fuels do not leave any residue after burning. 4. Liquid and gaseous fuels have higher calorific values than the solid fuels. In other words, for a given mass of the fuel, liquid and gaseous fuels produce more heat. 5. Liquid and gaseous fuels produce little or no smoke, whereas most of the solid fuels burn with smoke. 6. Liquid and gaseous fuels have relatively low ignition temperature and hence they burn more easily than solid fuels.

Disadvantages of Gaseous Fuels The main disadvantages of gaseous fuels are: 1. Very large storage tanks are needed for storing gaseous fuels. 2. They are highly inflammable, so chances of fire hazards are high in their use. 3. They are more costly than solid or liquid fuels. Smoke Smoke is a collection of tiny unburnt particles – very small carbon particles and tiny droplets of tar. Smoke is a collection of tiny solid, liquid and gas particles. Although smoke can contain hundreds of different chemicals and fumes, visible smoke is mostly carbon (soot), tar, oils and ash. Smoke occurs when there is incomplete combustion (not enough oxygen to burn the fuel completely). In complete combustion, everything is burned, producing just water and carbon dioxide. When incomplete combustion occurs, not everything is burned. Smoke is a collection of these tiny unburned particles. Each particle is too small to see with your eyes, but when they come together, you see them as smoke.

Smoke in a wood fire Wood is made up of:   

water volatile organic compounds – a compound is volatile if it evaporates (becomes a gas) when it is heated carbon

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minerals in the tree’s cells, like calcium, potassium and magnesium (which are non-burnable and become ash).

When you put wood on a hot fire, the smoke you see is the volatile organic compounds (hydrocarbons) evaporating from the wood. They start to evaporate at about 149°C. If the fire is hot enough, the hydrocarbons will burst into flames. Once they burn, there is no smoke because the hydrocarbons are turned into water and carbon dioxide.

Charcoal Charcoal is what is left after the hydrocarbons have been burnt off in wood. It glows because it is very hot and still has with the air (oxygen). After the fire has been burning for a while, most of the hydrocarbons (gases and smoke particles) have been released, and all that is left is charcoal, which is almost pure carbon with some minerals. The hot charcoal slowly burns with a red glow. There are no flames because charcoal will only produce carbon dioxide, which cannot be burned any further, unlike other vapours. Very little smoke is produced at this stage. The quicker a fire is reduced to glowing charcoal, the hotter it will be and the less smoke it will produce. The carbon combines with oxygen to produce carbon dioxide until all that is left at the end of the fire is the ash – the minerals. Charcoal is wood that has been heated to remove nearly all of the volatile gases and leave behind the carbon. That is why a charcoal fire burns with no smoke.