What Is Scotch Marine Boiler? | Types of Scotch Marine Boiler | Parts of Scotch Marine Boiler | Working of Scotch Marine Boiler

What Is Scotch Marine Boiler?

Scotch marine boiler is a common boiler commonly used on ships in marine works. These boilers are a type of fire-tube boiler. Scotch or tank-type marine steam boilers are used for marine works, in particular, because of their compactness, efficiency in operation, & ability to use any type of water.

It does not require a brickworks setting and external flues. In this article, we will learn about the construction, working, advantages, and application of Scotch marine boilers.

It is the most common boiler used on ships in marine works. It is a type of fire-tube boiler. After readings these articles, you will be able to know their construction.

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Types of Scotch Marine Boiler:

There are two main types of Scotch Marine Boilers:-

• Single Finished Scotch Marine Boiler.
• Double Ended Scotch Marine Boiler.

#1. Single Finished Scotch Marine Boiler

This boiler consists of a circular boiler shell of a large diameter and a short length. Single-end Scotch boilers have a distance of up to 3.5 meters. It consists of one to four furnaces, and these furnaces enter from the front end of the boiler. The Scotch boiler was a very common marine boiler used in steamships in many countries.

• Single-end steam boilers can have a length of up to 3.5 meters.
• Single-end steam boilers consist of one to four furnaces, and these furnaces enter from the front end of the boiler.

#2. Double Ended Scotch Marine Boiler

Older double-ended Scotch Marine boilers typically had vertical Galloway tubes manufactured in the combustion chamber. They were meant to promote the circulation of water in the boiler and thus contribute to reducing stresses in the material.

• A double-ended steam boiler has a length of up to 6.5 meters.
• In double-end Scotch Marine boilers, the furnaces are present at both ends of them. And the numbers of furnaces vary from 2 to 4 at each end.

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Parts of Scotch Marine Boiler:

The following are the important manufacturing parts of Scotch marine boilers:-

• Furnace
• Combustion chamber
• Smoke
• Chimney
• Boiler Shell

#1. Furnace

It is space above the Greater & below the boiler; it is employed to burn solid fuel inside the boiler. Single-ended boilers are fired with four furnaces. The furnaces are usually corrugated for strength.

In thises type of boiler, each furnace has its own combustion chambers. It is used to burn fuel inside the boiler. A single-ended Scotch marine boiler is fired with four furnaces.

The furnaces are usually corrugated for strength. Each furnace has its own combustion chamber.

#2. Combustion chamber

This is the space, usually below the boiler shell, to burn fuel so that water kept in the shell can generate steam. The combustion chamber consists of a fine plate, which needs to be in place, i.e., the top plate, the backplate, two side plates, and the tube plate.

It is a part of the boiler where fuel combustion takes place. The combustion chamber consists of fine plates, which need to remain, i.e., the top plate, backplate, two side plates, and tube plates.

There are several horizontally placed smoke taps that connect the combustion chamber to the chimney.

#3. Smoke Box

The smokebox contains several smoking tubes that are placed horizontally and connect the combustion chamber to the chimney. The smoke passes through these smoking tubes and eventually enters the chimney. The smoke passes through these smoking tubes and eventually enters the chimney.

#4. Chimney

The chimney is used to expel fumes and burnt gases from the boiler. The gases that flow through the chimney are released into the atmosphere. It is used to flush out the smoke and burnt gases from the boiler. Exhaust gases are released into the environment through the chimney.

#5. Boiler Shell

The boiler shell is made of a steel plate. This protects the internal parts of the boiler. All important fittings of the boiler are fitted on the boiler shell. It is made of steel plates bent in a cylindrical form and rinse or welded together. The boiler shell must have sufficient capacity to contain water and steam.

It protects the interiors of the boiler. All the necessary fittings of the boiler are adjusted on the shell of the boiler.

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Working of Scotch Marine Boiler:

The fuels are injected into the furnace through a fire hole. The fuel in the furnace is ignited through a fire hole. The burnt fuel enters the combustion chamber. Fuel combustion takes place here.

The heat generated in combustion chambers is used to heat the water around the combustion chamber. Water is converted into steam, and it is supplied to the steam turbine. The exhaust gases after combustion pass through the smoke tubes and reach the chimney.

The chimney releases these fumes and exhaust gases into the atmosphere. It has a drum of diameter from 2–5 to 3–5 m which is placed horizontally. These steam boilers can be single-ended or double-ended. Single steam boilers can have lengths of up to 3–5 meters, while those for double-ends can be up to 6–5 meters.

A single-ended boiler consists of one to four furnaces that enter from the front end of the boiler. A double-end boiler has furnaces at both ends and may have two to four furnaces at each end. Single-ended boilers are fired by four furnaces, as shown in the figure.

The furnaces are usually corrugated for strength. Each furnace has its own combustion chamber. The combustion chamber consists of a fine flat plate that needs to be in place, i.e., the top plate, backplate, two side plates, & the tube plate.

There are several horizontally placed smoke taps & that connect the combustion chamber to the chimney. The front & backplates of the shell are reinforced by longitudinal occupancy.

The wall of the combustion chamber is from the best heating surface. The furnace tube, smoke tube, and combustion chamber, all being surrounded by water, give a very large heatings surface area in proportion to the cubical size of the boiler.

The water seeps around the smokebox. The water level remains slightly above the combustion chambers. Flue gas from the combustion chamber is drafted through the smoke tubes, and finally, the chimney is lifted up. Smokeboxes are provided with a gate for cleaning tubes and smokeboxes.

• Fuel is burnt at the furnace, and hot burnt gases are produced. This hot burnt gas enters the combustion chamber. A large amount of heat is produced in the combustion chamber. The heat from the combustion chamber is used to heat the water surrounding it.
• The waters are converted into steam, & the steam is passed onto the turbine.
• The water surrounds the furnace, combustion chamber, and smoke tubes, and because of this, the Scotch Marine boiler provides a more heated surface for water.
• Burned exhaust gas travels from the smoke tubes to the chimney.
• The chimney releases these exhaust gases or fumes into the atmosphere.
• In this boiler, the water level is maintained slightly above the combustion chamber.

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Advantages of Scotch Marine Boiler:

Here, the different Advantages of the scotch marine boiler are as follows

• It is small in size.
• Boilers have the ability to operate any type of water.
• It has the ability to work in any type of water.
• This boiler does not require a brickwork setting and external flex.
• This boiler has considerable efficiency in operation.
• This boiler does not require a brickwork setting and external flues.

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Application of Scotch Marine Boiler:

Here, the different Applications of the scotch marine boiler are as follows

• These boilers are commonly used in marine works and ships.
• This is due to its compactness, efficiency in operation, and its ability to operate in any kind of water.
• These boilers are commonly used in marine works. The reason for this is its compactness, efficiency in operation, and ability to operate in any type of water.
• This boiler is used on ships.

Disadvantages of Scotch Marine Boiler:

Here, the different Disadvantages of the scotch marine boiler are as follows

• More floors area are required for a given output.
• Load variations cannot be easily controlled.
• It is used in small power plants.
• The rate of steam formation & steam quality is not much better than water tube boilers for suitable power generation.

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Frequently Asked Questions (FAQ)

Scotch Marine Boiler

Our two-pass, three-pass or four-pass Scotch Marine(Fire Tube) boilers are available in dry back, wetback, steam, or hot water versions; from 15 to 800 hp with pressures to 300 PSIG. Hurst Scotch Marine boilers are rated to 81% minimum efficiency.

Scotch Marine Boiler Working

Water is surrounded by the tube. The heat generated is much high and due to that, even the tube gets hot. Due to the heated tubes, the water starts getting heated and its phase is 1st water to saturated steam and saturated steam to superheated steam.

Scotch Marine Boiler Design and Operation

A Scotch marine boiler is a type of fire-tube boiler commonly used for marine applications and some industrial settings. It was named after the maritime industry in Scotland where it was widely adopted. The design and operation of a Scotch marine boiler are as follows:

Design:

1. Shell: The boiler has a cylindrical shell with a large diameter and a relatively short length. The shell is constructed using steel plates and is reinforced with stays to handle the internal pressure.
2. Furnace and Combustion Chamber: The furnace is located at the front end of the boiler, where the fuel (typically coal, oil, or gas) is burned. The combustion chamber is a space above the furnace where the hot gases from the fuel combustion pass through before entering the tubes.
3. Tubes: Numerous small-diameter tubes extend through the boiler shell, connecting the combustion chamber to the rear of the boiler. These tubes are surrounded by water and serve as the primary heat transfer surface. The hot gases pass through the tubes, transferring heat to the water.

Operation:

1. Fuel Combustion: The fuel, such as coal, oil, or gas, is burned in the furnace. The combustion process generates hot gases, including combustion products and unburned fuel particles.
2. Heat Transfer: The hot gases produced in the furnace pass through the combustion chamber and then flow through the tubes. As they travel through the tubes, the hot gases transfer their heat to the surrounding water, raising its temperature.
3. Water Circulation: The water in the boiler is circulated by natural convection or by a pump. The heated water becomes less dense and rises in the boiler, while the cooler water sinks and replaces it. This circulation ensures uniform heat distribution and prevents localized overheating.

Advantages of Using a Scotch Marine Boiler

This produces higher resistance and efficiency to fouling. As this boiler has a large diameter shell that contains water and steam and also a steam chest, the disengaging area produces good quality steam without the addition of mechanical separation.

Scotch Marine Boiler Manufacturers In the USA

There are several manufacturers in the United States that specialize in Scotch marine boilers. Here are some well-known manufacturers:

1. Cleaver-Brooks: Cleaver-Brooks is a leading manufacturer of industrial boilers, including Scotch marine boilers. They offer a range of models and sizes to suit various applications and industries.
2. Hurst Boiler & Welding Company: Hurst Boiler is another reputable manufacturer that produces Scotch marine boilers. They have been in operation for over 50 years and provide boilers for various industries, including commercial, industrial, and institutional sectors.
3. Johnston Boiler Company: Johnston Boiler Company has been manufacturing boilers since 1864. They offer a range of Scotch marine boilers that are known for their durability and efficiency.
4. Superior Boiler Works, Inc.: Superior Boiler Works is a manufacturer based in Hutchinson, Kansas. They produce a range of Scotch marine boilers for industrial, commercial, and institutional applications.
5. York-Shipley Global: York-Shipley Global is a manufacturer of boilers and combustion systems, including Scotch marine boilers. They offer customized solutions and have a long history in the industry.

Scotch Marine Boiler Maintenance and Troubleshooting

Maintaining and troubleshooting a Scotch marine boiler is crucial to ensure its safe and efficient operation. Here are some maintenance and troubleshooting guidelines for Scotch marine boilers:

Maintenance:

1. Regular Inspections: Schedule regular inspections by qualified personnel to check for any signs of wear, corrosion, or leaks. Inspections should include the boiler’s internal and external components, such as the shell, tubes, combustion chamber, and safety devices.
2. Water Treatment: Implement a proper water treatment program to prevent scale, corrosion, and fouling. This may include regular testing of water quality, chemical treatment, and periodic blowdown to remove impurities.
3. Cleaning and Soot Blowing: Clean the boiler’s fireside and waterside surfaces regularly to remove soot, ash, and scale buildup. Use appropriate cleaning methods and tools recommended by the manufacturer. Soot blowing may be required to remove deposits from the tubes.

Troubleshooting:

1. Insufficient Steam Production: If the boiler is not generating enough steam, check for low water levels, fuel supply issues, or blocked or scaled tubes that can impede heat transfer. Ensure proper fuel and air flow rates and verify that all control valves are operating correctly.
2. High Fuel Consumption: If the boiler is consuming excessive fuel, it could indicate combustion inefficiencies. Check for air leaks in the combustion chamber, ensure proper burner operation and fuel atomization, and inspect for fouled or damaged heat transfer surfaces that reduce boiler efficiency.
3. Low Water Pressure or Water Leaks: Inspect all water connections, valves, and fittings for leaks. Check the water supply pressure and verify that the feedwater pump is functioning correctly. Address any leaks promptly to prevent further damage.

Scotch Marine Boiler Efficiency and Fuel Consumption

They can take gas, natural gas, propane, diesel oil, or heavy oil as fuel, and they can achieve up to 81% fuel-efficiency.

Scotch Type Hot Water Boiler

The Scotch type boilers are the steam boilers running as flame-smoke typed, high efficiency, with high volume of water and fully cylindrical. Scotch type boilers may be run by the solid fuel in case of a special design. Scotch type boilers are the commonly used boilers by industrial plants.

The Fire Tubes in a Scotch Marine Boiler Are

The Scotch Marine Boiler is a fire-tube boiler, in that hot flue gases pass through tubes set within a tank of water. The general layout is that of a horizontal cylinder. One or more large cylindrical furnaces are in the lower part of the boiler shell. Above this is a large number of small-diameter fire-tubes.

Parts of Marine Boiler

• Safety valve.
• Main steam stop valve.
• Air vent cock.
• Two gauge glass level indicators.
• Feed check valve.
• Scum blow down valve.
• Bottom blow down valve.
• Salinity cock or test cock.

Boiler Internal Parts

• Burner. One of the most important parts of a boiler is the burner.
• Combustion Chamber.
• Heat exchanger.
• Aquastats.
• Backflow Valve.
• Circulator pumps.
• Controls.
• Deaerators/Condensers.

Boiler Furnace Types

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