Steam boiler working principle and types of boiler pdf

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steam boiler working principle and types of boiler pdf

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This is most basic definition of boiler.

Steam Boiler Working principle and Types of Boiler

A fire-tube boiler is a type of boiler in which hot gases pass from a fire through one or more tubes running through a sealed container of water. The heat of the gases is transferred through the walls of the tubes by thermal conduction , heating the water and ultimately creating steam. The fire-tube boiler developed as the third of the four major historical types of boilers: low-pressure tank or " haystack " boilers, flued boilers with one or two large flues, fire-tube boilers with many small tubes, and high-pressure water-tube boilers.

Their advantage over flued boilers with a single large flue is that the many small tubes offer far greater heating surface area for the same overall boiler volume. The general construction is as a tank of water penetrated by tubes that carry the hot flue gases from the fire. The tank is usually cylindrical for the most part—being the strongest practical shape for a pressurized container —and this cylindrical tank may be either horizontal or vertical.

This type of boiler was used on virtually all steam locomotives in the horizontal "locomotive" form. This has a cylindrical barrel containing the fire tubes, but also has an extension at one end to house the "firebox". This firebox has an open base to provide a large grate area and often extends beyond the cylindrical barrel to form a rectangular or tapered enclosure. The horizontal fire-tube boiler is also typical of marine applications, using the Scotch boiler ; thus, these boilers are commonly referred to as "scotch-marine" or "marine" type boilers.

In the locomotive-type boiler, fuel is burnt in a firebox to produce hot combustion gases. The firebox is surrounded by a cooling jacket of water connected to the long, cylindrical boiler shell. The hot gases are directed along a series of fire tubes , or flues , that penetrate the boiler and heat the water thereby generating saturated "wet" steam. The steam rises to the highest point of the boiler, the steam dome , where it is collected.

The dome is the site of the regulator that controls the exit of steam from the boiler. In the locomotive boiler, the saturated steam is very often passed into a superheater , back through the larger flues at the top of the boiler, to dry the steam and heat it to superheated steam. The superheated steam is directed to the steam engine's cylinders or very rarely to a turbine to produce mechanical work. Exhaust gases are fed out through a chimney , and may be used to pre-heat the feed water to increase the efficiency of the boiler.

Draught for firetube boilers, particularly in marine applications, is usually provided by a tall smokestack. In all steam locomotives since Stephenson's Rocket , additional draught is supplied by directing exhaust steam from the cylinders into the smokestack through a blastpipe , to provide a partial vacuum.

Modern industrial boilers use fans to provide forced or induced draughting of the boiler. Another major advance in the Rocket was large numbers of small-diameter firetubes a multi-tubular boiler instead of a single large flue. This greatly increased the surface area for heat transfer, allowing steam to be produced at a much higher rate. Without this, steam locomotives could never have developed effectively as powerful prime movers. For more details on the related ancestor type, see Flued boilers.

The earliest form of fire-tube boiler was Richard Trevithick 's "high-pressure" Cornish boiler. This is a long horizontal cylinder with a single large flue containing the fire. The fire itself was on an iron grating placed across this flue, with a shallow ashpan beneath to collect the non-combustible residue.

As the furnace relied on natural draught air flow , a tall chimney was required at the far end of the flue to encourage a good supply of air oxygen to the fire. For efficiency, the boiler was commonly encased beneath by a brick -built chamber.

Flue gases were routed through this, outside the iron boiler shell, after passing through the fire-tube and so to a chimney that was now placed at the front face of the boiler. The Lancashire boiler is similar to the Cornish, but has two large flues containing the fires. It was the invention of William Fairbairn in , from a theoretical consideration of the thermodynamics of more efficient boilers that led him to increase the furnace grate area relative to the volume of water.

Later developments added Galloway tubes after their inventor, patented in , [2] crosswise water tubes across the flue, thus increasing the heated surface area.

As these are short tubes of large diameter and the boiler continues to use a relatively low pressure, this is still not considered to be a water-tube boiler. The tubes are tapered, simply to make their installation through the flue easier.

The Scotch marine boiler differs dramatically from its predecessors in using a large number of small-diameter tubes. This gives a far greater heating surface area for the volume and weight. The furnace remains a single large-diameter tube with the many small tubes arranged above it. They are connected together through a combustion chamber — an enclosed volume contained entirely within the boiler shell — so that the flow of flue gas through the firetubes is from back to front.

An enclosed smokebox covering the front of these tubes leads upwards to the chimney or funnel. Typical Scotch boilers had a pair of furnaces, larger ones had three. Above this size, such as for large steam ships , it was more usual to install multiple boilers.

A locomotive boiler has three main components: a double-walled firebox ; a horizontal, cylindrical "boiler barrel" containing a large number of small flue-tubes; and a smokebox with chimney , for the exhaust gases. The boiler barrel contains larger flue-tubes to carry the superheater elements, where present. Forced draught is provided in the locomotive boiler by injecting exhausted steam back into the exhaust via a blast pipe in the smokebox.

Locomotive-type boilers are also used in traction engines , steam rollers , portable engines and some other steam road vehicles. The inherent strength of the boiler means it is used as the basis for the vehicle: all the other components, including the wheels, are mounted on brackets attached to the boiler. It is rare to find superheaters designed into this type of boiler, and they are generally much smaller and simpler than railway locomotive types.

The locomotive-type boiler is also a characteristic of the overtype steam wagon , the steam-powered fore-runner of the truck. In this case, however, heavy girder frames make up the load-bearing chassis of the vehicle, and the boiler is attached to this.

Certain railway locomotive boilers are tapered from a larger diameter at the firebox end to a smaller diameter at the smokebox end. This reduces weight and improves water circulation. A vertical fire-tube boiler VFT , colloquially known as the "vertical boiler", has a vertical cylindrical shell, containing several vertical flue tubes.

Horizontal return tubular boiler HRT has a horizontal cylindrical shell, containing several horizontal flue tubes, with the fire located directly below the boiler's shell, usually within a brickwork setting. Extensively used by Britain, before and in the early days of ironclads, the only protected place was below the waterline, sometimes under an armoured deck, so to fit below short decks, the tubes were not led back above the furnace but continued straight from it with keeping the combustion chamber in between the two.

Hence the name, and considerably reduced diameter, compared to the ubiquitous Scotch or return tube boiler. Further, on account of the length of the boiler, for an equal angle of inclination, the effect on the water-level is much greater. Finally, the unequal expansion of the various parts of the boiler is more pronounced, especially at the top and bottom, due to the increased ratio between the length and the diameter of the boiler; the local strains are also more severe on account of the comparatively feeble circulation in long and low boilers.

Also, the same length of a combustion chamber was much less effective on a direct tube than on a return tube boiler, at least without baffling. The immersion fired boiler is a single-pass fire-tube boiler that was developed by Sellers Engineering in the s. It has only firetubes, functioning as a furnace and combustion chamber also, with multiple burner nozzles injecting premixed air and natural gas under pressure. It claims reduced thermal stresses, and lacks refractory brickwork completely due to its construction.

Fire-tube boilers sometimes have water-tubes as well, to increase the heating surface. A Cornish boiler may have several water-tubes across the diameter of the flue this is common in steam launches. A locomotive boiler with a wide firebox may have arch tubes or thermic syphons. As firebox technology developed, it was found that placing a baffle of firebricks heat-resistant bricks inside the firebox to direct the flow of hot flue gasses up into the top of the firebox before it flowed into the fire tubes increased efficiency by equalizing the heat between upper and lower fire tubes.

To hold these in place, a metal bracket was used, but to prevent these brackets from burning and eroding away they were built as water tubes, with cool water from the bottom of the boiler moving upwards by convection as it heated, and carrying the heat away before the metal reached its failure temperature.

Another technique for increasing the heating surface is to include internal rifling inside the boiler tubes also known as Serve tubes. In homage to the Lancashire design, modern shell boilers can come with a twin furnace design.

A more recent development has been the reverse flame design where the burner fires into a blind furnace and the combustion gasses double back on themselves. This results in a more compact design and less pipework. The term "package" boiler evolved in the early- to midth century; it is used to describe residential heating boilers delivered to the installation site with all insulation, electrical panels, valves, gauges, and fuel burners already assembled by the manufacturer.

Other delivery methods more closely resemble prior practice from the coal burning era, when other components were added on-site to either a pre-assembled pressure vessel, or to a "knock-down" boiler, where the pressure vessel is delivered as a set of castings to be assembled on-site. As a general rule, factory assembly is much more cost-effective and the packaged boiler is the preferred option for domestic use.

Part-assembled deliveries are only used when necessary because of access limitations - e. Because the fire-flume boiler itself is the pressure vessel, it requires a number of safety features to prevent mechanical failure.

The fire-tube type boiler that was used in the Stanley Steamer automobile had several hundred tubes which were weaker than the outer shell of the boiler, making an explosion virtually impossible as the tubes would fail and leak long before the boiler exploded. In nearly years since the Stanleys were first produced, no Stanley boiler has ever exploded.

Each time a boiler cycles off and on, it can lose efficiency. When the fire starts combustion efficiency is usually lower until steady state conditions prevail.

When the fire stops the warm chimney continues to draw additional air from the interior space until it cools. Common provisions are to provide a primary piping loop with pump s and a secondary piping loop with pump s ; and either a variable speed controlled pump to transfer water from the primary loop to the secondary loop, or a 3-way valve to divert water from the secondary loop to the primary loop.

The efficiency increase depends on the fuel and the available energy to be recovered as a fraction of the total. Methane flue gas containing more available energy to recover than propane or fuel oil relatively less. The condensed water is corrosive due to dissolved carbon dioxide and sulfur oxides from the flue and must be neutralized before disposal.

The seasonal efficiency is an overall efficiency of the boiler over the entire heating season as opposed to the combustion efficiency which is the boiler's efficiency when actively fired, which excludes standing losses. The higher seasonal efficiency is partly because the lower boiler temperature used to condense the flue gas reduces standing losses during the off cycle. The lower boiler temperature precludes a condensing steam boiler and requires lower radiator temperatures in water systems.

The higher efficiency of operating in the condensing region isn't always available. To produce satisfactory domestic hot water frequently requires boiler water temperature higher than allows effective condensing on the heat exchanger surface. During cold weather the building's radiator surface area is usually not large enough to deliver enough heat at low boiler temperatures so the boiler's control raises the boiler temperature as required to meet heating demand.

These two factors account for most of the variability of the efficiency gains experienced at different installations. An intensive schedule of maintenance is needed to keep a high pressure railway steam boiler in safe condition. The tube plates, the fusible plug and the heads of the firebox stays should be checked for leaks. The correct operation of the boiler fittings, especially the water gauges and water feed mechanisms , should be confirmed. Steam pressure should be raised to the level at which the safety valves lift and compared with the indication of the pressure gauge.

The working life of a locomotive boiler is considerably extended if it is spared from a constant cycle of cooling and heating. The schedule for express engines was based on mileage.

Steam Boiler | Working Principle and Types Of Steam Boiler

Whether gas steam boiler principle is a substitute for coal-fired boilers and a secondary air for gas steam boiler, which is a boiler, for all of us, it is also a knowledge and understanding, have a comprehensive understanding and understanding, in order to ensure learning products, at the same time, you can get yourself some new knowledge from it, rather than nothing at all, which in turn affects the learning process of the product. Function gas boiler the ignition system that ignites the mixture of air and fuel, its main components are: the ignition transformer, the ignition electrode, a high voltage electrical cable fire. A more secure electronic ignition system called ignition pulse, is widely used Zhuoyi energy saving gas boiler manufacturers. Which facilitate saving, can simply press a finger, and safe, does not occur due to unexpected accidents occur flame, once the stall state occurs, the control system can close the solenoid valve, off the gas passage. Steam boiler is an energy conversion device, the energy input to the boiler fuel chemical energy, electrical energy, thermal energy and other forms of high temperature flue gas, and after converting the boiler, the steam output having a certain outside thermal energy, high-temperature hot water or an organic carrier.


Fuel (generally coal) is burnt in a furnace and hot gasses are produced. These hot gasses come in contact with water vessel where the heat of these hot gases transfer to the water and consequently steam is produced in the boiler. Then this steam is piped to the turbine of thermal power plant.


Boiler: Definition, Types, Applications, Necessity, and Fuel Used [With PDF]

Both gas and oil fired boilers use controlled combustion of the fuel to heat water. The key boiler components involved in this process are the burner, combustion chamber, heat exchanger, and controls. The burner mixes the fuel and oxygen together and, with the assistance of an ignition device, provides a platform for combustion. This combustion takes place in the combustion chamber, and the heat that it generates is transferred to the water through the heat exchanger. Controls regulate the ignition, burner firing rate, fuel supply, air supply, exhaust draft, water temperature, steam pressure, and boiler pressure.

In the last session, we had discussed Lamont boiler , Benson boiler , Cochran boiler , Babcock and Wilcox boiler in a detailed way whereas, in today's session, we will discuss What is a Boiler? Selection of a boiler, Essentials of Good boiler, Classification of a boiler, Diagram of the boiler, Boiler Mountings, and Boiler Accessories in a detailed way. The working principle of the boiler is very simple. For bathing, especially in winter, you need to heat water so you should not feel coolness around you.

types of fire tube boiler and its construction and mounting

A steam boiler or steam generator is a closed vessel in which water is heated, vaporized and converted into steam at a pressure higher than atmospheric pressure. There are large number of boiler designs, but they may be classified according to the following ways:.

What is a Steam Boiler – Working Principle, Types of Steam Boilers

A fire-tube boiler is a type of boiler in which hot gases pass from a fire through one or more tubes running through a sealed container of water. The heat of the gases is transferred through the walls of the tubes by thermal conduction , heating the water and ultimately creating steam. The fire-tube boiler developed as the third of the four major historical types of boilers: low-pressure tank or " haystack " boilers, flued boilers with one or two large flues, fire-tube boilers with many small tubes, and high-pressure water-tube boilers. Their advantage over flued boilers with a single large flue is that the many small tubes offer far greater heating surface area for the same overall boiler volume. The general construction is as a tank of water penetrated by tubes that carry the hot flue gases from the fire. The tank is usually cylindrical for the most part—being the strongest practical shape for a pressurized container —and this cylindrical tank may be either horizontal or vertical.

Fire-tube boiler A fire-tube boiler is a type of boiler in which hot gases from a fire pass through one or many more tubes running through a sealed container of water. The heat of the gases is transferred through the walls of the tubes by thermal conduction, heating the water and ultimately creating steam. A wide variety of fire tube boiler options are available to you, such as natural circulation, once through. In a scotch boiler, the furnace is a large diameter tube, within the boiler, surrounded by water. Some older, large scotch boilers had two or three furnaces but modern boilers typically have only one.


This article discusses What is a Steam Boiler, Types of Steam Boiler, Working Principle, Advantages, Disadvantages, Characteristics and Its Applications.


Steam Boilers: Parts, Working principle, and Types of Boilers (PDF)

Second, the clear purpose boiler "coal to gas"

Generally, a steam boiler is a type of closed container, designed with steel for heating the water to generate steam by some energy source like burning of fuel with eventually. The vapor generated may be delivered at low-pressure for the industrial progression work in sugar industries, cotton mills, and for generating steaming water that can be utilized for heat up fixing at much low-force. The capacity of the boiler should have ten liters of water and the working pressure must be 3. This article discusses what is a steam boiler and its types used in power stations for generating steam. A steam boiler is a power generation device, used for generating steam by applying the heat energy to water. The present boilers are more useful because it works with high pressure than old ones.

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COMMENT 3

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  • Steam boiler is nothing but a closed vessel combustion chamber which generates steam at a desired pressure by the combustion of fuel to water. Florian V. - 22.03.2021 at 20:48
  • And also you can download the PDF file of this article at the end of it. Karel G. - 24.03.2021 at 18:13

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