Let’s learn steam boiler along with basics, definition, parts, working principle, types, advantages, disadvantages, applications.
Let’s explore steam boiler!
Let’s explore the basics of a boiler or a steam boiler. What do you mean by steam boiler? As the name suggests, it is clearly understood that it is an equipment which is used to boil water to form steam.
Normally, steam is produced, so it is called a steam boiler!
For example, to understand the basics, take a closed container or a closed vessel with some water. Now, if you boil it, what will happen?
Hence, it is understood that if we boil water, high-pressure steam will be produced. Now, this steam is used in many industrial plants like thermal power plants, nuclear power plants, etc. to produce power. Hence, steam boiler is an essential part of many industries.
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.
The invention of the steam boiler has been started at the end of the 1700s with a simple kettle type boiler.
In 1967, the boiler was further developed for industries. Mainly G. Babcock and S. Wilcox were founded steam-generating industrial boilers.
In 1679, Denis Papin further developed the steam boiler with a safety valve and started to use it in many industries.
In 1891, Stirling Boiler Company started to make boilers and boost the various industry with the application of steam boilers.
In 1907, Stirling Boiler Company and Babcock & Wilcox Company are joined and started to make the best quality, customized, various capacity boilers.
A steam boiler is a complex combination of,
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 in 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.
It’s a very common question that how does a steam boiler work? Let’s try to understand in the simplest way,
Water is readily available and it is the lowest cost, easily handled liquid. When we talk about thermal energy, water becomes the first choice.
We don’t understand the energy contains in the water normally, but if you transform the water into steam, it can easily get an idea!
It means huge energy can be generated from water.
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Let’s see the working process of a steam boiler in step by step,
We can classify steam boilers into various types based on their uses/applications.
Factors on which the boiler can be classified are;
The tube of the boiler will either contain water or flue gases. Therefore, there are two types of boiler on the basis of tube content.
As the name suggests, the tube consists of water, basically, a water tube boiler means, water is contained inside the tubes.
The Fire-tube boiler, as the name implies, the tube consists of fire. Basically, in fire tube boilers, fire is contained inside the tubes.
They are also called smoke tube boilers.
We are dealing with two types of steam boilers based on the circulation of water. They are;
Water is present in a vessel, if we heat it the density of the bottom portion is decreased in comparison to the density of the upper portion.
In a natural boiler, unequal expansion of parts of the boiler can be prevented as we have uniform temperature everywhere in the boiler. Also overheating of boiler plates can be minimized.
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.
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.
We have the following types of boilers according to fuel used;
There are three types of boilers on the basis of pressure.
Work at a pressure range of 15-20 bar. It is used for process heating.
Work at a pressure range of 20 to 80 bar. It is used for power generation and process heating.
Work at a pressure above 80 bar. Loeffler boiler is a high-pressure boiler.
On this basis, two types of steam boilers are;
The shell axis is horizontal here; an example is the Lancashire boiler.
The shell axis is vertical here; an example is the Cochran boiler.
According to this factor, types of boilers are;
Internally fired boiler:
Externally fired boiler:
On the basis of mobility, boilers are following types;
This type of boiler is stationary, used in industries (sugar, chemical, textile, etc.) for process work and generation of thermal power. Examples;
This boiler can be moved from one to another. Examples are locomotive and marine boilers.
From the beginning, steam boilers were used in transportation to run trains and ships.
Some of the recent applications are;
We need a boiler with the following properties;
To select a boiler among many, the following factors should be considered;
It is the ratio of energy received by water to the energy supplied by the fuel for steam production.
Steam boiler efficiency = Energy gained by water/Total energy input = ṁs (h2-h1)/ṁ CV X 100
Three types of fuel are used in the boiler which are;
This fuel is in solid form. It includes wood, coal, pet coke, and rice husks.
This type of fuel is in liquid form. It includes furnace oil, light diesel oil.
This fuel is in gaseous form.
Complete details of the steam boiler and boiler types are specified. Hope it clarifies your concepts and helps you understand steam boiler working.
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