The boilers are most commonly used all over the world for different applications. There are multiple types of boilers, and the Lancashire boiler is one of them. It is a natural circulation boiler. The Lancashire boiler functions as a shell and tube heat exchanger, with the tubes facilitating the passage of exhaust gases, while the shell accommodates the flow of water. This article explains the Lancashire boiler working, components, and applications.
What is Lancashire Boiler?
The Lancashire boiler works according to the heat exchanger principle. A Lancashire boiler is an internal fire tube boiler in which heat is transferred from the exhaust gas to the water by a convection process. In 1844, William Fairbairn invented the Lancashire boiler.
It utilizes natural electricity to keep the water flowing in the boiler. Therefore, it is known as a natural circulation boiler.
This is an internally fired boiler because its furnace is installed inside the boiler. It produces low-pressure steam. The Lancashire boiler is a horizontally stationary fire tube boiler. This boiler has two flue tubes.
The thermal efficiency of the Lancashire boiler is around 80% to 90%. It has a diameter of 2 to 3 meters and a length of 7 to 9 meters. The Lancashire boilers are most commonly used for marines and locomotive engines.
Working of Lancashire Boiler
Lancashire boiler works on the heat exchanger principle. This is a shell and tube heat exchanger where the water circulates through the shell, and the exhaust gas flows through the tube.
Lancashire boiler works in the following way:
- First of all, the water is pumped into the economizer with the help of a feed pump.
- The economizer preheats the water by getting heat from the flow of gases. This preheating process also increases the efficiency of the boiler.
- After preheating, the economizer sends water into the shells of the boiler.
- As the water enters the boiler, the fire door starts burning the solid fuels.
- Due to the burning of solid fuels, heat is produced, which transfers to the flue gases.
- As the flue gases get heat, their temperature increases, and they start moving inside the fir tubes. These fire tubes fully submerge into the boiler water.
- The boiler has a small brick arc that stops the ashes’ entry into the boiler.
- When the flue gases move into the fire tubes, they transfer heat to the fire tubes.
- As the fire tubes get heat, they further transfer this heat to the boiler water through the convection process.
- The fire tube delivers 80 to 90% heat to the water.
- When the water gets heat from the fire tubes, the temperature of the water increases, and it converts into steam.
- A superheater uses to convert the produced steam into superheated condition.
- After all of these processes, the steam transfers to the desired area through a stop valve.
- As the flue gases pass through the fire tubes, they enter into the brickwork’s channel, where they make contact with the boiler shell and further heat up the water. This process increases the boiler efficiency.
- After all of these processes, the flue gases exit into the atmosphere via the boiler chimney.
Components of Lancashire Boiler
The major parts of the Lancashire Boiler are given below:
- Air preheater
- Safety valve
- Pressure Gauge
- Feed pump
- Ash pit
- Steam stop valve
- Blow off valve
- Water Level Indicator
- Fire door
- Fusible Plug
- Feed check valve
The shell is an outer component of the Lancashire boiler. It has a cylindrical shape. It provides protection to the internal parts of the boiler. The remaining components of the boiler are installed inside the shell of the boiler.
Read also: Different types of Boilers
2) Safety valve
The main objective of the safety valve is to prevent the boiler from busting. It uses to remove the steam from the boiler when the internal steam pressure exceeds the boiler bearing capacity. Therefore, a safety valve is a very important component of a boiler.
If you do not install a safety valve with your boiler, your boiler may bust when there is excess steam pressure.
3) Pressure Gauge
The pressure gauge uses to measure the internal pressure of the boiler. This gauge always installs with the boiler. It measures the internal pressure of the boiler and shows this pressure valve in the form of PSI. Through the pressure gauge, you can easily manage the pressure of your boiler.
4) Water Level Indicator
The water level indicator is also one of the important components of the Lancashire boiler. This unit indicates the water level of the boiler. As the water level becomes less than the desired level, the feed pump activates and pumps the water from the storage tank to the boiler.
Therefore, if you are a boiler operator, you must be familiar with this unit to maintain the water level of the boiler properly.
Read More: Different types of Pumps
5) Steam Stop Valve
The purpose of this valve is to stop the flow of steam into the steam delivery pipes from the boiler. When there is no more need of steam to the system, Turn OFF this valve, and steam will not flow into the steam delivery pipes.
Read Also: Different Types of Valves
6) Blow-off Valve
The blow-off valve is also known as a drain valve. It uses to eliminate useless wastes such as sludge, debris, and other debris from the boiler base. The removal of the sludge from the boiler is very important because sludges cause problems during the boiler working.
7) Fire door
A fire door is a place inside the boiler where solid fuel burns to produce flue gases. These gases circulate inside the boiler to convert water into steam.
8) Feed Check Valve
This valve of the boiler uses to introduce water from the feed pump into the boiler. It is a one-way valve, and it stops the water from flowing back from the boiler into the feed pump.
9) Fusible Plug
The fusible plug works in the same way as the safety valve. It also prevents the boiler from bursting.
When your boiler’s safety stops working due to a problem then the fusible plug starts working in place of the safety valve. This valve removes the excess amount of pressure from the boiler. As the inner pressure becomes more than the boiler limit, the fusible plug opens and prevents the boiler from any damage.
10) Ash Pit
After the burning of solid fuel, it converts into ash. These produced ashes move into the ash pit. The ash pit only uses to collect the ash from the boiler.
As the same of the superheater represents that it uses to superheat the steam produced in the boiler. It converts the steam into very high-pressure and temperature steam.
This is an external part of the Lancashire boiler. The economizer takes heat from the flue gases and pre-heats the water.
The purpose of the economizer is to increase the boiler’s performance and efficiency.
13) Air Preheater
The air preheater has the same operation as an economizer. It also increases the efficiency of the boiler.
The objective of the air preheater is to recover heat from the exhaust gases by heating the air delivered to the furnace.
Almost all types of boilers have a manhole. This hole uses to fix the problems of the boiler’s internal parts. When there is any broken or failed part inside the boiler, the operator enters the boiler by using a Manhole to resolve the problem.
Construction of Lancashire Boiler
The Lancashire boiler has a large drum length from 9m to 10m and a diameter from 4m to 6m. This drum further has two fire tubes submerged in the water. The boiler has a cylindrical shell filled with water. The shell installs in the wall of brick to create multiple passages for the flue gases flow.
This boiler also has an economizer which preheats the water before the water enters the boiler. The fire tube tapers slightly to its rear end to rise the speed of the flue gas.
A fire door uses to burn solid fuel. As the flue gases get heat, they start flowing inside the fire tubes. The boiler consists of many other important parts such as a water gauge, safety valve, feed check valve, pressure gauge, etc.
The safety valve controls the internal steam pressure of the boiler and removes the excess pressure from the boiler. At the end of each side of the channel, there is a damper to regulate the airflow.
Advantages and Disadvantages of Lancashire Boiler
The advantages and disadvantages of Lancashire boilers are given below:
Advantages of Lancashire Boiler
- They have the capacity to fulfill the requirements of the load easily.
- These boilers have easy inspection and cleaning.
- The thermal efficiency of the Lancashire boiler is between 80% to 90%.
- These types of boilers have easy operation.
- They have high reliability
- It consumes less electricity because it is a natural boiler.
- The Lancashire boiler requires low maintenance.
- They have the capacity to produce a large amount of steam.
Disadvantages of Lancashire Boiler
- It requires more floor space.
- They have corrosion problems.
- It has large in size.
- These boilers have leakage issues.
- The main disadvantage of the Lancashire boiler is that it can generate only low-pressure steam.
- These boilers have inadequate area for the grate because of the small diameter of the flue tubes.
- They get extensive time to produce steam.
Applications of Lancashire Boilers
- The Lancashire boilers are most commonly used to run the steam turbine.
- These boilers also use to drive locomotive engines.
- These boilers use in different industries such as tire industries, sugar industries, textile industries, paper industries, etc.
- They are used in marine applications.
Difference between Water Tube Boiler and Fire Tube Boiler
|Water Tube Boiler
|Fire Tube Boiler
|The water tube boiler is an externally fired boiler.
|The fire tube boiler is internally fired.
|These are high-pressure boilers.
|These are medium or low-pressure boilers.
|They have pressure from 70 to 100 bar.
|They have pressure up to 20 bar.
|In this boiler, flue gases flow outside the tubes while water moves inside the tubes.
|In this boiler, water flows outside the tubes while flue gases flow inside the tubes.
|The cleaning and repair of the water tube boiler are easy.
|The cleaning and repair of the fire tube boiler are very hard.
|They have a high rate of steam production.
|They have a low steam production rate.
|There is a high risk of boiler burst.
|There is less risk of burst because of low pressure.
|It takes less floor area.
|It takes a large floor area.
|It has more efficiency than a fire tube boiler.
|It has less efficiency.
|It has an easy construction.
|It has complex construction.
|This boiler has a low maintenance cost.
|This boiler has a high maintenance cost.
|It has easy maintenance.
|The maintenance of this boiler is very hard.
|This boiler needs a small diameter of the shell.
|This boiler needs a large shell diameter.
|It can easily handle load fluctuation.
|It can’t handle load fluctuation.
|It has low weight.
|It has a high weight.
|These boilers are used for large industries.
|These are used for textile industries and sugar mills.
|Lancashire boiler and Benson Boiler are examples of the water tube boiler.
|Locomotive Boiler and Cornish Boiler are examples of fire tube boiler.
Who invented Lancashire boiler?
In 1844, William Fairbairn invented the Lancashire boiler.
How many numbers of flue tubes in Lancashire boiler is?
The Lancashire boiler has two flue tubes.
What is the difference between Lancashire Boiler and Cornish boiler?
The main difference between these two boilers is that the Cornish boiler has only one flue tube while Lancashire has two flue tubes.