Boilers: Components, Types & Working Principle

In this article, I will share with you the components, types and working principles of boilers.


A boiler is a closed vessel in which water is heated and gets converted into steam and the steam is supplied to the point of use.


The steam produced from the boiler can be used for heating, cooling, cleaning and so many other domestic uses.


That is for hot water boilers that are used for domestic purposes.


We have steam boilers that are used for industrial applications, and those are the boilers I will be discussing in this article.


Boilers are considered for use in many domestic and industrial applications due to the following benefits;

  • Boilers have higher energy efficiency.
  • They also emit low emissions of toxic gases since they only use pure water.
  • Boilers provide an even distribution of heat.


For you to understand the working principle of steam boilers you have to know the components and their functions.


Components of boilers.

The components of the boilers are what enable the boilers to have higher efficiency.


Without some of these components, the boilers would have been less effective.


These are the main components of the boilers;

Pressure vessel; the pressure vessel contains the liquid or gas that is under high pressure and temperature.


A water level indicator; is an instrument that is used to show the level of water in a boiler.


Feed water tank; this is the tank that is used to store treated water that will be used by the boiler for steam generation.


Control panel; the control panel is used to control several measures of the steam that is produced by the boilers. These measures are pressure, temperature, burning fire rate, air supply, exhaust draft etc.


A pressure gauge; it’s used to measure the pressure value of the steam.


Feed pump; this is a pump that is used to pump water to the boiler. It also ensures a continuous supply of water in the boiler.


Stop valve; this valve is used to control the flow of the liquid in the boiler or the steam out of the boiler.


Safety valve; this valve is used to control the safety values of the boiler. If the pressure is too high within the boiler then it will be the function of the safety valve to bring it to a considerable range.


Blow off c*ck; it’s used to blow off mud, dirt and debris out of the water and also to empty the boiler tank.


A grate; is a platform where the fuel burns to produce the heat that is required to heat the water.


An economizer; it’s used as a heat exchanger that transfers the heat to the water entering the boiler thus increasing the energy content of the steam, and making the boiler efficiency.


You might like this: Boiler Economizers: Function, Types, Design And Operation and Requirements Of Steam Plant Economizer


Deaerator tank; this is a tank that is used to remove dissolved gasses in the feed water by the use of pressure. Removal of these dissolved gases e.g oxygen prevents corrosion of the boiler.


Burner; it’s used to provide heat by mixing oxygen and fuel with the help of an ignition device the heat is produced.


Superheater; it’s used to heat the steam before it’s taken to the turbine, this increases the energy content of the steam and reduces the saturation of the steam. A highly saturated steam causes corrosion of the boiler.


Air pre-heater; it’s used to heat the air in the air chamber before it enters the boiler to improve steam generation in the boiler.


You might like this: Air Preheaters in Steam Boilers: Function, Types and Working Principles


Boiler systems and their functions.

The boiler has several systems that result in its efficiency.


These are boilers’ systems;

Feed water system; the feed water system ensures that there is a continuous supply of water needed by the boiler and also regulates the water.


You might like this: Effects of Impurities of Feed Water In Boiler (+Prevention) and Feed Water Treatment: Types And How They Work


The combustion system or fuel system; is the system that is used to provide the heat needed to heat the water. This system combines oxygen and fuel and with the help of an ignition device, heat is produced.


This is a very important system of the boiler since without it there is no way the steam will be generated within the boiler.


You might like this: Overfeed & Underfeed Stokers: Classification and Working Principles and Pulverized Fuel Burner: Components, Types, Requirements and Working Principle


Steam system; this system of a boiler is essential as it collects and controls the amount of steam produced within a boiler. It’s the same system that directs the steam produced to the point of use via the pipes or tubes.


Chemical monitoring system; this system is used to evaluate the number of chemicals entering the boiler. The chemicals can be from the feed water tank or the chemical added to the boiler to treat water.


There has to be a moderate amount of chemicals within the boiler as much or fewer chemicals will affect the efficiency of the boiler.


A Reserved osmosis system; is a system used to treat water by using pressure to force the water across a semi-permeable membrane leaving impurities behind on the reject stream.



Types of boilers;

There are mainly two types of boilers according to the flow of water and hot gases;

  • Water-tube boilers.
  • Fire-tube boilers.


1. Water-tube boilers.

Water tube boilers are boilers that contain the water to be heated within tubes. These tubes containing water are heated and the heat is transferred to the water.


The heat flows over the tubes but it doesn’t come in contact with the water being heated.


There are further categories of water tube boilers; we have horizontal straight water tube boilers, bent water tube boilers and cyclone-fired water tube boilers.


Water-tube boilers have higher steam efficiencies since they generate superheated steam which makes them a preferred choice when it comes to power production and in applications where dry high-pressure steam is required.


Water-tube boilers are used in pulp and paper manufacturing industries due to their higher efficiencies.


You might like this: Advantages And Disadvantages Of Water Tube Boilers


2. Fire-tube boilers.

In fire tube boilers the products of combustion (hot gases) pass through tubes that are surrounded by water being heated.


The tube transfers its heat to the water surrounding the tubes.


You might like this: Advantages And Disadvantages Of Fire Tube Boilers


The fire-tube boilers are categorized further into the following boilers;

  1. Horizontal fire tube boilers.
  2. Vertical tubular fire tube boilers.
  3. Compact fire tube boilers.
  4. Short fire tube boilers.
  5. Horizontal return fire tube boilers.


Working principle of boilers.

We have different types of boilers but they all work under the same principle.


Boilers work on the principle of conversation of heat energy from the steam to kinetic energy that is used to drive the steam turbine to produce energy.


When the boiler is heated steam is generated, and the steam is directed via pipes to the point of use, it can be a steam turbine if energy production is required.


The steam energy is used to drive the steam turbine blades and eventually, this leads to the production of electricity via the generator.


Thanks for reading, if you have any questions leave your comment, and see you in my next article.


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