A steam boiler is a power generation device that generates steam by applying heat energy to water. It is in the form of a closed vessel made up of steel in which combustion of fuel occurs to produce heat energy. It is also called a steam generator.
A steam boiler is a critical part of a thermal powerplant, therefore, it’s important for us to have knowledge about the steam boiler.
Main Partsof Steam Boiler
A steam boiler is a complex combination of,
water space, and
Let’s try to understand each of the parts of the boiler to have a basic idea.
The boiler shell is a hollow cylindrical body made of steel. The heat transfer and steam generation will occur in this part. The ends of the shell are closed with endplates.
Here the combustion of fuel occurs to produce heat energy. The burner creates combustion in this chamber by burning various types of fuel. It lies over the grate and below the shell.
These are the fittings and devices for proper functioning and safety of the boiler (pressure gauge, safety valve, stop valve, etc.)
These are the integral devices fitted on the boiler to improve its efficiency (superheater, air preheater, economizer, etc.)
It is the space on which fuel is burnt. It is built of several cast-iron bars which are used to support fuel placed on it.
This space is exposed to hot gases on one side and water on the other.
Water space and steam space
These two areas are part of the shell. Water space is the volume occupied by water in the shell and steam space is the area where steam got collected inside the shell of the boiler.
Working Principle of Steam Boiler
It’s a very common question that how does a steam boiler work? Let’s try to understand in the simplest way,
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Water feeding to the shell of the boiler at operating pressure.
Fuel is burnt in a furnace and hot gases are produced.
These hot gases come in contact with water space.
The heat transfer occurs from hot gases to water in the shell.
The water gets heated and converted into steam.
The steam is collected in steam space for further use.
This steam can be used for power production, air conditioning and to perform any industrial process.
Types of Steam Boiler
We can classify steam boilers into various types based on their uses/applications.
Factors on which the boiler can be classified are;
In this type of boiler, pumps are used to maintain the continuous flow of water. The centrifugal pump creates the pressure for water circulation. Forced boilers are high pressure and high capacity boilers.
It has a higher rate of heat transfer; easy control of fluctuation load and steam generation is quick.
We can reduce the size and weight of the boiler by using forced circulation of water.
According to the number of tubes used
Based on the number of tubes, we have two types of boilers;
Single tube boiler
As the name specifies, a single tube boiler contains only one fire tube or water tube. Cornish boiler is a single tube boiler.
This boiler has a number of tubes for flue gases or water. An example of a multi-tube boiler is the Cochran boiler.
According to the heat source used
We have the following types of boilers according to fuel used;