Construction of Lancashire Boiler with Explained Parts
Lancashire Boiler- Everything You Need to Know
The Lancashire boiler is an old type of boiler, and even having passed decades, is still commonly used in several different types of plants. It is high demand in sugar mills, chemical plants, and textile industries where more amount of low-pressure steam is required for processing. The simple design, higher thermal efficiency and reliability are some of the major factors behind its popularity.
Lancashire boiler is a type of boiler. It is categorized as a fire tube boiler (wherein the flue gases produced from burning fuel pass through tubes surrounded by water in the boiler shell). This setup siphons off heat from the hot gases into the water, creating steam.
Lancashire boiler pressure is also in the range of 10 to 16 bar, it can be used for low— to medium-pressure steam process. (upon design and fuel, ca 8500 kg/h steam generator) The internal construction, flow of gases, and water circulation paths of the Lancashire boiler can be learnt with the help of its diagram, which makes it easier to do operation and maintenance.
Historical Background
The Lancashire boiler was invented by Sir William Fairbairn in 1844. Throughout the Industrial Revolution, industries required a reliable and efficient steam boiler, and this design was just that at the time. The Lancashire boiler had a large shell, two fire tubes,, and seating in brickwork, and was a long-lasting and efficient method of steam generation.
Fundamental Concept of Lancashire Boiler
Lancashire Boiler works on the principle of a Shell and Tube heat exchanger. In this design, hot flue gases flow through the fire tubes, and water fills the shell on the outside. E Energy is transferred (by conduction and convection) from the hot gases to the water in each shell, producing steam (in the upper part of the shell).
As it is a natural circulation boiler, the water flows due to the difference in density between hot and cold water, allowing the water to circulate within the boiler shell without the aid of mechanical pumps.
Lancashire Boiler Parts and Construction.
Components of Lancashire Boiler Construction The Lancashire Boiler consists of various significant components, all contributing to its effective and safe operation.
Main Shell
The first part of the boiler consists of a big horizontal cylinder, with a diameter of around 4–6m and a length of 9m–10m, which is the main boiler shell. It has both water and steam volume; the top half volume is steam, while the bottom half is water.
Fire Tubes
The shell consists of two big fire tubes with almost 40% of the shell diameter. These so-called fire tubes are where combustion gases pass, transferring heat to the water that surrounds them.
Furnace
At one end of the fire tubes is the furnace, which consumes solid fuels (such as coal). At the mouth of each fire tube is the grate (where the fuel goes).
Seating and Flue Passages in Brick
- The boiler sits on brickwork, forming three flue passages:
- Central flue in the centre of the fire tubes.
- Outer shell side flues.
- Flue under the shell at the bottom.
With these passages, hot gas could flow smoothly, and heat could be transferred to the water as much as possible. The flows are realized; thus, the Lancashire boiler diagram explains these passages.
Mountings and Accessories
The Lancashire boiler manual lists important mountings and accessories necessary to operate it safely:
- Bias gauge to read bias pressure.
- Water level metric to monitor water levels.
- Safety valves for letting off excess pressure.
- A heat exchanger is also known as an economizer, and it is used to preheat the incoming feedwater.
- An optional superheater improves steam quality.
- They keep the Lancashire boiler running safely and efficiently when in action.
In-depth Operation of Lancashire Boiler
FEEDING FUEL ON THE GRATE The Lancashire boiler is fired by feeding fuel (normally coal) on the grate. Gas is created within the fire tubes and moves through the complete duration of the fire tubes, transferring temperature to the surrounding water.
Exiting the fire tubes, the flue gases travel downwards through the bottom flue passage, losing more heat to the underside of the shell. The flue gases then pass through the side flue passages for more heat exchange before exiting out the chimney.
Hot gases enter from one end, pass over tubing or under a series of baffles, and go out through the other end in a series of passes around the shell for maximum heat transfer. This system consists of several passes, enabling gradual build-up of Lancashire boiler pressure so that steam generation is optimal in speed and efficiency.
This steam collects in the top section of the shell and can be used directly for processes or routed through a superheater to produce superheated steam.
Pros and Cons of Lancashire Boilers
As with any piece of equipment, the pros and cons of a Lancashire boiler must be weighed when determining its suitability for different industrial applications.
Advantages
Find a Way in Simple Construction and Operation
The Lancashire boiler construction is comparatively simple, which leads to easy operation and maintenance of the boiler. The Lancashire boiler manual provides operational directions for the operators.
1. High Thermal Efficiency
The efficiency of this boiler is extremely high, between 80-90% if installed with economizers and superheater.
2. Big Steam Production Ability
Its large water and steam capacity allows it to accommodate fluctuating loads, making it ideal for those industries that need continuous steam availability.
3. Natural Circulation
The natural circulation of the boiler minimizes power consumption because no additional circulation pumps have to be installed.
4. Cleaning and Inspection
Its horizontal design and big fire tubes enable internal cleaning as well as tube inspection, contributing to its longevity in operation.
Disadvantages
- Large Floor Space Requirement
- Wide layouts and brickwork seating need lots of square footage, which is not likely for smaller plants.
- Restricted to Low-Pneumatic Services
- The pressure range of the Lancashire boiler is also low due to which this boiler cannot be used in power generation which needs high-pressure steam.
Slow Startup
The high quantity of water also means that the boiler requires more time to come up to temperature and produce some steam, with less flexibility during rapid start situations.
Leakage Issues
Regular inspection is critical, given the many brick-lined flue passages through which the gas must flow, making a gas leak more likely.
Limited Grate Area
Grounded in the physics of combustion, the design limits the grate area by the diameter of the fire tube, restricting the ability to efficiently burn fuel and often resulting in combustion loss.
Uses of Lancashire Boiler
The Lancashire boiler is a low to medium-pressure application boiler, and it is used in:
- Sugar mills.
- Textile industries.
- Chemical processing plants.
- Food processing units.
- Paper mills.
Because of its robust design and very reliable nature, it is still common even with the advent of modern water tube boilers.
Conclusion
The Lancashire boiler continues to be important in industrial steam generation, particularly in applications requiring large volumes of low-pressure steam. Its simple design, high thermal efficiency, and ease of operation make it a preferred choice in many industries despite the emergence of newer boiler technologies.
When considering a boiler for industrial use, it’s essential to evaluate the Lancashire boiler’s advantages and disadvantages to determine if it fits the specific operational requirements. This historical yet practical boiler design can deliver years of reliable service with proper maintenance guided by the Lancashire boiler manual.
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