COMBUSTION AND FOSSIL FUELS

By Jayanarayan.J,

Mars House

WHAT IS COMBUSTION ? Combustion is defined as the process of

burning of a substance in the presence of air or oxygen with the liberation of light and heat.

Or Combustion or burning is the

sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species.

LETS SEE SOME IMAGES.

WHAT DO BURNING A SUBSTANCE PRODUCE ?• Burning a substance produces Light and heat

HOW IS LPG USEFUL TO US?• LPG is used for Cooking

COMBUSTIBLE SUBSTANCES

Substances that burn in air to produce light and heat are called combustible substances

Eg- Paper , Wood , Kerosene , LPG .

NON-COMBUSTIBLE SUBSTANCES

Substances that do not burn in air to produce light and heat are called combustible substances

Eg-Water , Sand , Glass , Cement .

SPONTANEOUS COMBUSTION

Spontaneous combustion is a type of combustion which occurs without an external ignition source. It is usually a slow process that can take several hours of decomposition/oxidation with heat build up to a point of ignition.

• Coal can spontaneously ignite when exposed to oxygen which causes it to react and heat up when there is insufficient ventilation for cooling.

• Pyrite oxidation is often the cause of coal spontaneous ignition in old Mine tailings.

• Pistachio nuts are highly flammable when stored in large quantities, and are prone to self-heating and spontaneous combustion.

• Large cow manure piles can spontaneously combust during conditions of extreme heat.

RAPID COMBUSTION

It’s a Type of combustion where lot of heat and light is released in a short time span.

Sometimes, a large volume of gas is liberated in combustion besides the production of heat and light.

COMPLETE COMBUSTION

In complete combustion, the reactant burns in oxygen, producing a limited number of products. When a hydrocarbon burns in oxygen, the reaction will only yield carbon dioxide and water. When elements are burned, the products are primarily the most common oxides. Carbon will yield carbon dioxide, nitrogen will yield nitrogen dioxide, sulfur will yield sulfur dioxide, and iron will yield iron(III) oxide.

INCOMPLETE COMBUSTION

Incomplete combustion occurs when there isn't enough oxygen to allow the fuel to react completely to produce carbon dioxide and water. It also happens when the combustion is quenched by a heat sink such as a solid surface or flame trap.

EXPLOSION

The sudden evolution of large quantities of gas creates excessive pressure that produces a loud noise. Combustion need not involve oxygen; e.g., hydrogen burns in chlorine to form hydrogen chloride with the liberation of heat and light characteristic of combustion.

THE END