Boiler Repairs Manor Park, E12, Boiler Breakdown Emergency Service

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# 28/11/2017 à 06:17 JamesGop (site web)
A boiler is a closed vessel where water or other fluid is heated. The fluid does not boil. (In North America, the word "furnace" is generally used if the purpose is not to boil the fluid.) The heated or vaporized liquid exits the boiler for use in a variety of heating or procedures applications,[1][2] including water heating, central heating, boiler-based power era, cooking, and sanitation.

Materials
The pressure vessel of the boiler is usually manufactured from steel (or alloy steel), or of wrought iron historically. Stainless steel, especially of the austenitic types, is not found in wetted elements of boilers due to stress and corrosion corrosion cracking.[3] However, ferritic stainless is often found in superheater sections that will not come in contact with boiling drinking water, and electrically heated stainless shell boilers are allowed under the Western european "Pressure Equipment Directive" for creation of steam for sterilizers and disinfectors.[4]
https://en.wikipedia.org/wiki/Boiler
In live steam models, copper or brass is often used since it is more fabricated in smaller size boilers easily. Historically, copper was often used for fireboxes (particularly for vapor locomotives), due to its better formability and higher thermal conductivity; however, in newer times, the high price of copper often makes this an uneconomic choice and cheaper substitutes (such as steel) are used instead.

For much of the Victorian "age of steam", the only materials used for boilermaking was the highest quality of wrought iron, with set up by rivetting. This iron was from specialist ironworks, such as at Cleator Moor (UK), noted for the high quality of their rolled plate and its suitability for high-reliability use in critical applications, such as high-pressure boilers. In the 20th century, design practice moved towards the use of metal instead, which is more powerful and cheaper, with welded building, which is quicker and requires less labour. It should be mentioned, however, that wrought iron boilers corrode far slower than their modern-day steel counterparts, and are less susceptible to localized pitting and stress-corrosion. This makes the durability of old wrought-iron boilers far superior to those of welded steel boilers.

Cast iron might be utilized for the heating vessel of home water heaters. Although such heaters are usually termed "boilers" in some countries, their purpose is to produce warm water usually, not steam, and they also run at low pressure and stay away from boiling. The brittleness of cast iron helps it be impractical for high-pressure vapor boilers.
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Energy
The foundation of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, or gas. Electric steam boilers use level of resistance- or immersion-type heating system elements. Nuclear fission is also used as a heat source for generating steam, either directly (BWR) or, generally, in specialised warmth exchangers called "vapor generators" (PWR). High temperature recovery vapor generators (HRSGs) use heat rejected from other procedures such as gas turbine.

Boiler efficiency
there are two solutions to gauge the boiler efficiency 1) direct method 2) indirect method

Immediate method -direct approach to boiler efficiency test is more usable or even more common

boiler efficiency =Q*((Hg-Hf)/q)*(GCV *100 ) Q =Total vapor stream Hg= Enthalpy of saturated steam in k cal/kg Hf =Enthalpy of feed drinking water in kcal/kg q= quantity of gas use in kg/hr GCV =gross calorific value in kcal/kg like pet coke (8200 kcal/KG)

indirect method -to gauge the boiler efficiency in indirect method, we are in need of a following parameter like

Ultimate analysis of gasoline (H2,S2,S,C moisture constraint, ash constraint)
percentage of O2 or CO2 at flue gas
flue gas temperature at outlet
ambient temperature in deg c and humidity of air in kg/kg
GCV of fuel in kcal/kg
ash percentage in combustible fuel
GCV of ash in kcal/kg
Configurations
Boilers can be classified in to the following configurations:

Container boiler or Haycock boiler/Haystack boiler: a primitive "kettle" where a fire heats a partially filled drinking water container from below. 18th century Haycock boilers produced and stored large amounts of very low-pressure steam generally, hardly above that of the atmosphere often. These could burn off wood or most often, coal. Efficiency was very low.
Flued boiler with a couple of large flues-an early forerunner or type of fire-tube boiler.

Diagram of the fire-tube boiler
Fire-tube boiler: Here, drinking water partially fills a boiler barrel with a little volume still left above to accommodate the steam (steam space). This is the type of boiler used in all steam locomotives nearly. Heat source is in the furnace or firebox that needs to be kept permanently surrounded by water in order to keep up the temp of the heating surface below the boiling point. The furnace can be situated at one end of the fire-tube which lengthens the road of the hot gases, thus augmenting the heating system surface which can be further increased by making the gases invert direction through a second parallel pipe or a bundle of multiple tubes (two-pass or return flue boiler); additionally the gases may be studied along the sides and then beneath the boiler through flues (3-pass boiler). In case of a locomotive-type boiler, a boiler barrel stretches from the firebox and the hot gases pass through a lot of money of fire tubes inside the barrel which greatly increases the heating system surface in comparison to a single pipe and further increases heat transfer. Fire-tube boilers have a comparatively low rate of steam production usually, but high steam storage capacity. Fire-tube boilers burn off solid fuels mainly, but are easily adjustable to those of the liquid or gas variety.

Diagram of a water-tube boiler.
Water-tube boiler: In this type, tubes filled with water are arranged inside a furnace in a true quantity of possible configurations. The water pipes connect large drums Often, the lower ones including drinking water and the top ones vapor and drinking water; in other situations, like a mono-tube boiler, water is circulated by a pump through a succession of coils. This kind generally provides high steam creation rates, but less storage capacity than the above mentioned. Water tube boilers can be designed to exploit any warmth source and are generally preferred in high-pressure applications because the high-pressure water/vapor is included within small size pipes which can withstand the pressure with a thinner wall.
Flash boiler: A flash boiler is a specialized kind of water-tube boiler in which pipes are close jointly and water is pumped through them. A flash boiler differs from the type of mono-tube vapor generator in which the tube is permanently filled up with water. Super fast boiler, the pipe is kept so hot that the water give food to is quickly flashed into vapor and superheated. Flash boilers got some use in cars in the 19th century which use continued in to the early 20th century. .

1950s design steam locomotive boiler, from a Victorian Railways J class
Fire-tube boiler with Water-tube firebox. Sometimes both above types have been mixed in the next manner: the firebox consists of an assembly of water pipes, called thermic siphons. The gases then go through a typical firetube boiler. Water-tube fireboxes were installed in many Hungarian locomotives,[citation needed] but have met with little success in other countries.
Sectional boiler. In a cast iron sectional boiler, sometimes called a "pork chop boiler" water is included inside solid iron areas.[citation needed] These sections are assembled on site to generate the finished boiler.
Safety
See also: Boiler explosion
To define and secure boilers safely, some professional specialized organizations such as the American Culture of Mechanical Designers (ASME) develop criteria and regulation codes. For example, the ASME Boiler and Pressure Vessel Code is a typical providing an array of guidelines and directives to ensure compliance of the boilers and other pressure vessels with protection, security and design standards.[5]

Historically, boilers were a way to obtain many serious injuries and property destruction due to badly understood engineering principles. Thin and brittle steel shells can rupture, while badly welded or riveted seams could start, leading to a violent eruption of the pressurized steam. When drinking water is changed into vapor it expands to over 1,000 times its original travels and volume down steam pipes at over 100 kilometres each hour. As a result of this, steam is a superb way of moving energy and high temperature around a niche site from a central boiler house to where it is necessary, but without the right boiler give food to water treatment, a steam-raising flower will suffer from range formation and corrosion. At best, this boosts energy costs and can result in poor quality vapor, reduced efficiency, shorter plant life and unreliable operation. At worst, it can result in catastrophic loss and failing of life. Collapsed or dislodged boiler pipes can also squirt scalding-hot vapor and smoke out of the air intake and firing chute, injuring the firemen who insert the coal in to the fireplace chamber. Extremely large boilers providing hundreds of horsepower to use factories could demolish entire structures.[6]

A boiler which has a loss of give food to drinking water and is permitted to boil dry out can be extremely dangerous. If give food to drinking water is then sent in to the vacant boiler, the small cascade of incoming drinking water instantly boils on contact with the superheated metal shell and leads to a violent explosion that cannot be managed even by security vapor valves. Draining of the boiler can also happen if a leak occurs in the steam source lines that is bigger than the make-up drinking water source could replace. The Hartford Loop was invented in 1919 by the Hartford Vapor Boiler and Insurance Company as a method to assist in preventing this problem from taking place, and therefore reduce their insurance promises.[7][8]

Superheated steam boiler

A superheated boiler on a steam locomotive.
Main article: Superheater
Most boilers produce steam to be utilized at saturation temperature; that is, saturated steam. Superheated steam boilers vaporize water and then further warmth the vapor in a superheater. This provides steam at much higher heat, but can reduce the overall thermal efficiency of the vapor generating vegetable because the higher vapor temperature takes a higher flue gas exhaust heat range.[citation needed] There are several ways to circumvent this problem, by giving an economizer that heats the feed water typically, a combustion air heating unit in the hot flue gas exhaust path, or both. A couple of benefits to superheated vapor that may, and will often, increase overall efficiency of both steam generation and its utilization: benefits in input heat range to a turbine should outweigh any cost in additional boiler problem and expense. There can also be practical limitations in using damp vapor, as entrained condensation droplets will damage turbine blades.

Superheated steam presents unique safety concerns because, if any system component fails and allows steam to flee, the ruthless and temperature can cause serious, instantaneous injury to anyone in its path. Since the escaping steam will initially be completely superheated vapor, detection can be difficult, although the extreme heat and sound from such a leak indicates its presence clearly.

Superheater operation is similar to that of the coils on an fresh air conditioning unit, although for a different purpose. The steam piping is directed through the flue gas path in the boiler furnace. The heat in this field is normally between 1,300 and 1,600 °C (2,372 and 2,912 °F). Some superheaters are glowing type; that is, they absorb high temperature by rays. Others are convection type, absorbing warmth from a liquid. Some are a combination of both types. Through either method, the extreme heat in the flue gas path will heat the superheater steam piping and the steam within also. While the temp of the vapor in the superheater rises, the pressure of the steam will not and the pressure remains exactly like that of the boiler.[9] Virtually all steam superheater system designs remove droplets entrained in the steam to prevent harm to the turbine blading and associated piping.

Supercritical steam generator

Boiler for a charged power place.
Main article: Supercritical steam generator
Supercritical steam generators are generally used for the production of electric power. They operate at supercritical pressure. In contrast to a "subcritical boiler", a supercritical steam generator operates at such a higher pressure (over 3,200 psi or 22 MPa) that the physical turbulence that characterizes boiling ceases to occur; the liquid is neither water nor gas but a super-critical liquid. There is absolutely no era of vapor bubbles within water, because the pressure is above the critical pressure point at which steam bubbles can form. As the fluid expands through the turbine stages, its thermodynamic state drops below the critical point as it can work turning the turbine which converts the electrical generator from which power is eventually extracted. The fluid at that time may be a mixture of steam and liquid droplets as it goes by into the condenser. This results in less fuel use and for that reason less greenhouse gas production slightly. The word "boiler" should not be used for a supercritical pressure steam generator, as no "boiling" occurs in this device.
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Accessories
Boiler fittings and accessories
Pressuretrols to control the steam pressure in the boiler. Boilers generally have 2 or 3 3 pressuretrols: a manual-reset pressuretrol, which functions as a security by setting the upper limit of vapor pressure, the working pressuretrol, which handles when the boiler fires to maintain pressure, and for boilers equipped with a modulating burner, a modulating pressuretrol which controls the amount of fire.
Basic safety valve: It is utilized to relieve pressure and stop possible explosion of the boiler.
Water level signals: They show the operator the level of fluid in the boiler, known as a view cup also, water measure or water column.
Bottom level blowdown valves: They offer a way for removing solid particulates that condense and rest on the bottom of the boiler. As the name implies, this valve is situated directly on the bottom of the boiler usually, and is occasionally opened to use the pressure in the boiler to push these particulates out.
Continuous blowdown valve: This allows a small level of water to flee continuously. Its purpose is to avoid the water in the boiler becoming saturated with dissolved salts. Saturation would business lead to foaming and cause water droplets to be carried over with the vapor - a condition known as priming. Blowdown is often used to monitor the chemistry of the boiler water also.
Trycock: a kind of valve that is often use to manually check a water level in a container. Most found on a drinking water boiler commonly.
Flash tank: High-pressure blowdown enters this vessel where the vapor can 'flash' safely and be used in a low-pressure system or be vented to atmosphere while the ambient pressure blowdown flows to drain.
Automatic blowdown/continuous heat recovery system: This technique allows the boiler to blowdown only when make-up water is flowing to the boiler, thereby transferring the utmost amount of heat possible from the blowdown to the makeup water. No flash tank is normally needed as the blowdown discharged is near to the temperatures of the makeup water.
Hand holes: These are steel plates installed in openings in "header" to permit for inspections & installation of pipes and inspection of internal surfaces.
Vapor drum internals, some display screen, scrubber & cans (cyclone separators).
Low-water cutoff: It is a mechanical means (usually a float change) that is utilized to turn from the burner or shut down fuel to the boiler to avoid it from jogging once the drinking water moves below a certain point. If a boiler is "dry-fired" (burnt without drinking water in it) it can cause rupture or catastrophic failure.
Surface blowdown series: It provides a means for removing foam or other light-weight non-condensible chemicals that have a tendency to float together with water inside the boiler.
Circulating pump: It is designed to circulate water back to the boiler after they have expelled some of its heat.
Feedwater check valve or clack valve: A non-return stop valve in the feedwater collection. This can be fitted to the medial side of the boiler, just below the water level, or to the very best of the boiler.[10]
Top feed: With this design for feedwater injection, the water is fed to the very best of the boiler. This can reduce boiler fatigue triggered by thermal stress. By spraying the feedwater over some trays water is quickly heated and this can reduce limescale.
Desuperheater pipes or bundles: Some tubes or bundles of tubes in water drum or the vapor drum made to cool superheated steam, in order to supply auxiliary equipment that does not need, or may be damaged by, dry out steam.
Chemical injection line: A connection to add chemicals for controlling feedwater pH.
Steam accessories
Main steam stop valve:
Steam traps:
Main steam stop/check valve: It is used on multiple boiler installations.
Combustion accessories
Fuel oil system:gas oil heaters
Gas system:
Coal system:
Soot blower
Other essential items
Pressure gauges:
Feed pumps:
Fusible plug:
Inspectors test pressure gauge attachment:
Name dish:
Registration dish:
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