Combustion & Flame

By

Vishnu M Nair

Index• Basic needs• How to extinguish Fire• The Ignition temperature• Inflammable combustion• Rapid & Spontaneous Combustion• Zones Of Candle Flame• Explosion• Fuel• Fuel Efficiency• Global Warming• Acid Rain

BASIC NEEDS

Basic Needs

The major conditions for a fire to burn is1. The presence of Oxygen2. The presence of fuel3. The temperature to reach flash point

Combustion – A chemical process in which a substance reacts with oxygen to give off heat is called combustion.

Basics of Combustion and Flame

We now understand that fire be seen with the help of the above

Q1. What will you do if you see a uncontrolled fire?

How to extinguish fire?

The answer to that question is so simple. Fire can only burn with presence of oxygen and

fuel and if temperature is above flash point.So to extinguish fire remove away any of these

For Example1. By denying the access of oxygen Example: If fire is on a human body we should

cover him tightly with a blanket like that on the picture below

2. By taking away the fuel 3. By decreasing the temperature below flash

pointThis can be done by poring water over the fire

Q. What will you do if the fire is caused by an electric short circuit

In such a case DO NOT TRY TO EXTINGUISH IT WITH WATER.

As water may come in contact with electric shock which could lead to serious injuries or even DEATH

The Ignition Temperature

The lowest temperature at which a substance

catches fire is called its Ignition TemperatureIt is essential for a substance to reach its ignition

temperature to burn

Given here are some fuels and its ignition temperature

Sl no. Fuel Temperature

1 Diesel 210 degrees2 Petrol 246 degrees3 Butane 405 degrees4 Paper 450 degrees5 Magnesium 473 degrees6 Hydrogen 536 degrees7 Triethylborane -20 degrees

Inflammable substance

The Substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances

Some examples are: Petrol, Alcohol, Liquid Petroleum Gas

RAPID COMBUSTION AND SPONTANEOUS COMBUSTION

Rapid Combustion and Spontaneous Combustion

Rapid Combustion: Gas burns rapidly and produces heat and light. Such combustion is known as rapid combustion.

Rapid Combustion and Spontaneous Combustion

Spontaneous Combustion: The type of combustion in which a material suddenly bursts into flames, without the application of any apparent cause is called Spontaneous Combustion

Zones of Candle Flame

Explosion

When a cracker is ignited, a sudden reaction takes place with the evolution of heat, light and sound. A large amount of gas formed in the reaction is liberated. Such a reaction is called explosion.

Fuel

The substance that undergoes combustion is said to be combustible or FUEL

Fuel

Liquid

Solid

Gas

Know more on fuels

A Good Fuel – A good fuel is:-• Readily Available• Cheap• Burns easily in air• And does not leave any undesirable substance

behind.

Fuel Efficiency

The amount of heat produced on complete combustion of 1 kg fuel is called its calorific value. The calorific value is expressed in a unit called kilojoules per kg (kj/kg).

Fuel Calorific Value

Cow dung cake 6000-8000

Wood 17000-22000

Coal 25000-33000

Petrol 45000

Kerosene 45000

Diesel 45000

Methane 50000

LPG 55000

Biogas 35000-40000

Hydrogen 150000

BURNING OF FUELS LEADS TO HARMFUL PRODUCTS

Global Warming

Combustion of most fuels releases carbon dioxide in environment. Increased carbon dioxide in air is believed to cause global warming

A bear that lost his home because of ice melting

Acid Rain

Burning of coal and diesels releases sulphur dioxide gas. Oxides of sulphur and nitrogen dissolve in rain water and forms acids.

Such a rain is called acid rain.

Acid rain

THE END

DONE BYVISHNU

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