It is a fire tube boiler because the flue gases pass via the fire tube, which is housed within the boiler shell. Steam is produced at low pressure by this boiler. Because the furnace is housed within the boiler, it is an internally fired boiler.
Flue gases often flow via the fire tube. It is a fire tube boiler because it is located within the boiler’s body or shell. Because the furnace used to be within the boiler, the Lancashire Boiler is an internally fired boiler. This boiler uses natural circulation and produces steam at low pressure.
Well, in this reading, I’ll be exploring what Lancashire is, its application, principle, diagram, construction, parts, advantages and disadvantages & how it works.
Let’s Get Started!
What Is Lancashire Boiler?
The Lancashire boiler is a fire tube boiler with natural circulation that fires horizontally and internally. This boiler has a maximum evaporation capacity of 8500 kg of steam per hour and can raise steam to a pressure of one bar, steam is produced at low pressure by this boiler.
Because the furnace is housed within the boiler, it is an internally fired boiler, in the sugar and chemical product sectors, where steam is needed for processing tasks, this boiler is very popular. In the year 1844, Sir William Fairbairn created this boiler. It is a fire tube boiler because the flue gases pass via the fire tube, which is housed within the boiler shell.
Lancashire boilers are widely used in modest installations, providing electricity for industry operations and heating buildings. They are commonly used in paper, textile, sugar, and tire sectors.
Fire-tube boilers, also used in steam locomotives, operate as heat exchangers, with hot boiler gases circulating outside tubes containing water. These natural circulation boilers function as shell and tube heat exchangers, transferring heat from exhaust gases to water through convection.
A boiler is a heat exchanger with a sizable drum, fire tubes, and brickwork. The drum has two fire tubes, making up 40% of the shell’s diameter. The water drum is situated over the brickwork, with gaps between the bricks and the drum. Flue gases pass through the side, bottom, and fire tubes, transferring more heat to the water.
Water fills half of the drum, leaving the top empty for steam. The furnace is located at one end of the fire tubes, while the low brick prevents ash and unburned fuel from flowing into the fire tubes. The boiler includes additional mountings and accessories like an economizer, super heater, safety valve, pressure gauge, and water gauge for better functionality.
How Does Lancashire Boiler Works?
Heat exchangers of the shell and tube type are used in Lancashire boilers. Burning occurs at the grate. The economizer raises the temperature of the water as it is pushed into the shell. Water is now halfway into the shell. The water surrounds the fire tube completely.
Flue gases are produced at the grate when the fuel is charged. The fire tube is the first barrier that these flue gases go through. The water receives 80–90% of its heat from these fire tubes. The bottom tube is where the backward flue gases exit after giving water an additional 8–10% of their heat.
The residual flue gases exit via the side tube, which transfers 6-8% of the heat to the water. Brick acts as a thermal insulator since it is a lower conductor of heat.
The steam generated inside the drum shell is extracted from the top side and, if necessary, passes via a super heater. For process operations, the steam created is so removed.
The Lancashire Boiler system comprises various components, including a water level indicator, pressure gauge, safety valve, steam stop valve, feed check valve, blow off cock, man hole, fusible plug, grate, and fire door.
The water level indicator measures the water level, while the pressure gauge measures the steam pressure within the boiler. The safety valve prevents excessive steam pressure from damaging the boiler.
The steam stop valve halts and allows steam to enter the steam pipe, while the feed check valve regulates water flow from the feed pump to the boiler. The blow off cock removes sediments at the bottom of the boiler, while the man hole allows for maintenance or cleaning.
The boiler’s furnace extinguishes the fire when the water level drops below dangerous levels. The grate is used for burning coal, and a fire door allows fuel to be burned inside or outside the boiler. The ash pit collects fuel after burning.
The Lancashire boiler is a natural circulation boiler with high thermal efficiency of 80-90%, allowing it to generate large amounts of steam. It is reliable, easy to clean, and meets load requirements.
However, it requires more time to generate steam, has limited grate area due to small diameter fire tubes, cannot generate high pressure steam, requires more floor space, and has leakage issues.
