Boiler Repairs Golders Green, Hampstead Garden Suburb, NW11, Boiler Breakdown Emergency Service

# 28/11/2017 à 06:21 JamesNer (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 never to boil the fluid.) The warmed or vaporized liquid exits the boiler for use in a variety of heating system or procedures applications,[1][2] including drinking water heating, central heating, boiler-based power generation, cooking food, and sanitation.

The pressure vessel of a boiler is usually manufactured from steel (or alloy steel), or of wrought iron historically. Stainless steel, of the austenitic types especially, is not found in wetted elements of boilers due to corrosion and stress corrosion breaking.[3] However, ferritic stainless is often used in superheater sections that won't be exposed to boiling drinking water, and electrically heated stainless shell boilers are allowed under the Western "Pressure Equipment Directive" for production of steam for sterilizers and disinfectors.[4]
In live steam models, copper or brass is often used since it is more easily fabricated in smaller size boilers. Historically, copper was often used for fireboxes (particularly for vapor locomotives), because of its better formability and higher thermal conductivity; however, in more recent times, the high price of copper often makes this an uneconomic choice and cheaper substitutes (such as metal) are used instead.

For a lot of the Victorian "age of vapor", the only material used for boilermaking was the highest grade of wrought iron, with assembly by rivetting. This iron was often extracted 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 instead moved towards the utilization of metal, which is more powerful and cheaper, with welded construction, which is quicker and requires less labour. It ought to be mentioned, however, that wrought iron boilers corrode far slower than their modern-day steel counterparts, and are less vunerable to localized stress-corrosion and pitting. This makes the longevity of older wrought-iron boilers significantly more advanced than those of welded steel boilers.

Cast iron might be utilized for the heating vessel of home drinking water heaters. Although such heaters are usually termed "boilers" in a few countries, their purpose is usually to produce hot water, not steam, and they also run at low pressure and stay away from boiling. The brittleness of cast iron makes it impractical for high-pressure steam boilers.
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The source of heating 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 elements. Nuclear fission can be used as a heat source for generating steam also, either straight (BWR) or, generally, in specialised temperature exchangers called "vapor generators" (PWR). Temperature recovery steam generators (HRSGs) use the heat rejected from other processes such as gas turbine.

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

Immediate method -immediate approach to boiler efficiency test is more functional or even more common

boiler efficiency =Q*((Hg-Hf)/q)*(GCV *100 ) Q =Total vapor circulation Hg= Enthalpy of saturated vapor in k cal/kg Hf =Enthalpy of give food to water in kcal/kg q= level of gasoline 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 fuel (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 gasoline in kcal/kg
ash percentage in combustible fuel
GCV of ash in kcal/kg
Boilers can be classified into the following configurations:

Container boiler or Haycock boiler/Haystack boiler: a primitive "kettle" in which a open fire heats a partially filled water pot from below. 18th century Haycock boilers produced and stored large amounts of very low-pressure steam generally, often hardly above that of the atmosphere. These could burn off wood or frequently, coal. Efficiency was suprisingly 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, water partially fills a boiler barrel with a little volume remaining above to accommodate the steam (steam space). This is the kind of boiler used in almost all steam locomotives. The heat source is in the furnace or firebox that needs to be kept permanently surrounded by water in order to keep up the temperature of the heating surface below the boiling point. The furnace can be situated at one end of a fire-tube which lengthens the path of the hot gases, thus augmenting the heating system surface which can be further increased by making the gases reverse direction through another parallel tube or a bundle of multiple tubes (two-pass or come back flue boiler); on the other hand the gases may be studied along the sides and then beneath the boiler through flues (3-move boiler). In case of a locomotive-type boiler, a boiler barrel stretches from the firebox and the hot gases go through a bundle of fire pipes inside the barrel which greatly increases the heating surface compared to a single pipe and further enhances heat transfer. Fire-tube boilers usually have a comparatively low rate of steam creation, but high vapor storage capacity. Fire-tube boilers burn solid fuels mainly, but are readily adaptable to people of the gas or water variety.

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

1950s design vapor locomotive boiler, from a Victorian Railways J class
Fire-tube boiler with Water-tube firebox. Sometimes the two above types have been combined in the following manner: the firebox consists of an set up of water tubes, called thermic siphons. The gases go through a typical firetube boiler then. Water-tube fireboxes were installed in many Hungarian locomotives,[citation needed] but have met with little success far away.
Sectional boiler. Inside a solid iron sectional boiler, sometimes called a "pork chop boiler" water is contained inside ensemble iron areas.[citation needed] These sections are assembled on site to create the finished boiler.
See also: Boiler explosion
To define and secure boilers safely, some professional specialized organizations such as the American Culture of Mechanical Engineers (ASME) develop standards and regulation rules. For instance, the ASME Boiler and Pressure Vessel Code is a typical providing an array of rules and directives to ensure compliance of the boilers and other pressure vessels with protection, security and design standards.[5]

Historically, boilers were a source of many serious injuries and property destruction due to badly understood engineering principles. Thin and brittle metal shells can rupture, while badly welded or riveted seams could start, resulting in a violent eruption of the pressurized vapor. When water is changed into steam it expands to over 1,000 times its original volume and moves down vapor pipes at over 100 kilometres each hour. Because of this, steam is a great way of moving energy and warmth around a niche site from a central boiler house to where it is necessary, but with no right boiler give food to water treatment, a steam-raising flower are affected from size formation and corrosion. At best, this boosts energy costs and can result in poor quality vapor, reduced efficiency, shorter plant life and unreliable procedure. At worst, it can lead to catastrophic failing and loss of life. Collapsed or dislodged boiler pipes can also spray scalding-hot vapor and smoke out of the air intake and firing chute, injuring the firemen who load the coal in to the fireplace chamber. Extremely large boilers providing hundreds of horsepower to use factories could demolish entire buildings.[6]

A boiler which has a loss of feed water and is permitted to boil dry out can be extremely dangerous. If give food to water is then sent into the unfilled boiler, the small cascade of inbound water instantly boils on connection with the superheated metallic shell and leads to a violent explosion that can't be controlled even by protection vapor valves. Draining of the boiler can also happen if a leak occurs in the vapor source lines that is larger than the make-up water supply could replace. The Hartford Loop was created in 1919 by the Hartford Steam Boiler and INSURANCE PROVIDER as a strategy to assist in preventing this problem from happening, and thereby reduce their insurance promises.[7][8]

Superheated steam boiler

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

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

Superheater operation is similar to that of the coils on an fresh air conditioning unit, although for a different purpose. The vapor piping is directed through the flue gas path in the boiler furnace. The temp in this field is typically between 1,300 and 1,600 °C (2,372 and 2,912 °F). Some superheaters are glowing type; that is, they absorb heat by radiation. Others are convection type, absorbing high temperature from a fluid. 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 heat range of the steam in the superheater goes up, the pressure of the vapor does not and the pressure remains the same as 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 power seed.
Main article: Supercritical steam generator
Supercritical steam generators are generally used for the production of electric power. They operate at supercritical pressure. As opposed to a "subcritical boiler", a supercritical vapor generator operates at such a high pressure (over 3,200 psi or 22 MPa) that the physical turbulence that characterizes boiling ceases to occur; the fluid is liquid nor gas but a super-critical fluid neither. There is absolutely no generation of steam bubbles within water, because the pressure is above the critical pressure point of which steam bubbles can develop. As the fluid expands through the turbine phases, its thermodynamic condition drops below the critical point as it can work turning the turbine which converts the power generator from which power is ultimately extracted. The liquid at that point may be considered a mix of steam and liquid droplets as it passes in to the condenser. This results in slightly less energy use and for that reason less greenhouse gas production. The term "boiler" shouldn't be used for a supercritical pressure vapor generator, as no "boiling" occurs in this device.
Boiler Repairs Golders Green, Hampstead Garden Suburb, NW11, Boiler Breakdown Emergency Service Boiler Repairs Golders Green, Hampstead Garden Suburb, NW11, Boiler Breakdown Emergency Service!..
Boiler fittings and accessories
Pressuretrols to control the vapor pressure in the boiler. Boilers generally have two or three 3 pressuretrols: a manual-reset pressuretrol, which functions as a basic safety by setting top of the limit of steam pressure, the operating pressuretrol, which handles when the boiler fires to maintain pressure, as well as for boilers equipped with a modulating burner, a modulating pressuretrol which controls the quantity of fire.
Safety valve: It can be used to relieve pressure and prevent possible explosion of a boiler.
Water level indications: They show the operator the level of liquid in the boiler, also known as a view glass, water measure or water column.
Bottom level blowdown valves: They offer a way for removing solid particulates that condense and lie on the bottom of a boiler. As the name indicates, this valve is located directly on underneath of the boiler usually, and is occasionally opened up to use the pressure in the boiler to drive these particulates out.
Constant 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 drinking water droplets to be transported over with the steam - an ailment known as priming. Blowdown is also often used to monitor the chemistry of the boiler drinking water.
Trycock: a kind of valve that is often use to manually check a liquid level in a container. Most commonly found on a drinking water boiler.
Flash container: High-pressure blowdown enters this vessel where the vapor can 'flash' safely and become found in a low-pressure system or be vented to atmosphere as the ambient pressure blowdown flows to drain.
Automatic blowdown/continuous heat recovery system: This system allows the boiler to blowdown only when makeup water is moving to the boiler, thereby transferring the maximum amount of heat possible from the blowdown to the make-up water. No flash tank is generally needed as the blowdown discharged is close to the temp of the makeup water.
Hand holes: These are metal plates installed in openings in "header" to permit for inspections & installation of tubes and inspection of inner surfaces.
Vapor drum internals, some 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 energy to the boiler to prevent it from jogging once the drinking water goes below a certain point. If a boiler is "dry-fired" (burned without water in it) it can cause rupture or catastrophic failing.
Surface blowdown range: It offers a way for removing foam or other light-weight non-condensible chemicals that tend to float on top of the water inside the boiler.
Circulating pump: It is designed to circulate drinking 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 series. This may be suited to the relative aspect of the boiler, just below the water level, or to the very best of the boiler.[10]
Top give food to: Within this design for feedwater injection, the water is fed to the very best of the boiler. This may reduce boiler fatigue caused by thermal stress. By spraying the feedwater over some trays water is quickly heated and this can reduce limescale.
Desuperheater tubes or bundles: A series of pipes or bundles of pipes in the water drum or the steam drum designed to cool superheated steam, in order to supply auxiliary equipment that does not need, or may be damaged by, dry steam.
Chemical substance injection line: A link with 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
Gasoline oil system:energy 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 plate:
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