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A boiler is a closed vessel in which drinking water or other liquid is heated. The fluid does not necessarily boil. (In THE UNITED STATES, the word "furnace" is normally used if the purpose is never to boil the fluid.) The warmed or vaporized liquid exits the boiler for use in various processes or heating system applications,[1 - [2 - including drinking water heating, central heating system, boiler-based power era, cooking food, 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 used in wetted elements of boilers due to corrosion and stress corrosion breaking.[3 - However, ferritic stainless is often found in superheater sections that will not come in contact with boiling water, and electrically heated stainless steel shell boilers are allowed under the European "Pressure Equipment Directive" for production of steam for sterilizers and disinfectors.[4 - https://en.wikipedia.org/wiki/Boiler - https://en.wikipedia.org/wiki/Boiler In live steam models, copper or brass is often used because it is more fabricated in smaller size boilers easily. Historically, copper was often used for fireboxes (particularly for vapor locomotives), because of 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 group of vapor", the only materials used for boilermaking was the highest grade of wrought iron, with assembly by rivetting. This iron was from specialist ironworks, such as at Cleator Moor (UK), observed for the high quality of their rolled plate and its own suitability for high-reliability use in critical applications, such as high-pressure boilers. In the 20th century, design practice transferred towards the use of metal instead, which is stronger and cheaper, with welded structure, which is quicker and requires less labour. It ought to be noted, however, that wrought iron boilers corrode considerably slower than their modern-day metal counterparts, and are less susceptible to localized stress-corrosion and pitting. This makes the longevity of old wrought-iron boilers much more advanced than those of welded steel boilers.
Cast iron may be used for the heating vessel of home water heaters. Although such heaters are usually termed "boilers" in a few countries, their purpose is usually to produce hot water, not steam, and so they run at low pressure and stay away from boiling. The brittleness of cast iron helps it be impractical for high-pressure vapor boilers. Boiler Repairs Seven Sisters, N15, Boiler Breakdown Emergency Service http://boiler-repairs-seven-sisters.co.uk - Show more... Energy 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 system elements. Nuclear fission is also used as a heat source for producing steam, either straight (BWR) or, generally, in specialised high temperature 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 methods to gauge the boiler efficiency 1) direct method 2) indirect method
Direct 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 flow Hg= Enthalpy of saturated steam in k cal/kg Hf =Enthalpy of feed drinking water in kcal/kg q= level of fuel use in kg/hr GCV =gross calorific value in kcal/kg like family pet coke (8200 kcal/KG)
indirect method -to measure the boiler efficiency in indirect method, we are in need of a subsequent 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 energy 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 water box from below. 18th century Haycock boilers generally produced and stored large quantities of very low-pressure steam, often hardly above that of the atmosphere. These could burn wood or frequently, coal. Efficiency was very low. Flued boiler with one or two large flues-an early type or forerunner of fire-tube boiler.
Diagram of the fire-tube boiler Fire-tube boiler: Here, drinking water partially fills a boiler barrel with a small volume remaining above to support the steam (vapor space). This is the kind of boiler used in all steam locomotives nearly. The heat source is in the furnace or firebox that needs to be held completely surrounded by the water in order to keep up the heat range of the heating system 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 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); alternatively the gases may be taken along the sides and then beneath the boiler through flues (3-move boiler). In case there is 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 system surface compared to a single pipe and further improves heat transfer. Fire-tube boilers usually have a comparatively low rate of steam production, but high vapor storage capacity. Fire-tube boilers mostly burn solid fuels, but are readily adaptable to people of the gas or liquid variety.
Diagram of the water-tube boiler. Water-tube boiler: In this type, pipes filled with water are arranged in the furnace in a genuine amount of possible configurations. The water pipes connect large drums Often, the lower ones containing water and top of the ones water and steam; in other cases, like a mono-tube boiler, water is circulated by a pump through a succession of coils. This type gives high vapor creation rates generally, but less storage capacity than the above. Water pipe boilers can be made to exploit any high temperature source and are generally preferred in high-pressure applications since the high-pressure drinking water/steam is included within small size pipes which can withstand the pressure with a thinner wall. Flash boiler: A flash boiler is a specialized type of water-tube boiler where tubes are close collectively and water is pumped through them. A flash boiler differs from the type of mono-tube vapor generator where the tube is permanently filled with water. In a flash boiler, the pipe is kept so hot that the water give food to is quickly flashed into vapor and superheated. Flash boilers experienced 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 next manner: the firebox contains an set up of water pipes, called thermic siphons. The gases go through a conventional firetube boiler then. Water-tube fireboxes were installed in many Hungarian locomotives,[citation needed - but have fulfilled with little success far away. Sectional boiler. In a solid iron sectional boiler, sometimes called a "pork chop boiler" water is included inside solid iron areas.[citation needed - These areas are assembled on site to make the finished boiler. Safety See also: Boiler explosion To define and secure boilers safely, some professional specialized organizations like the American Society of Mechanical Technical engineers (ASME) develop specifications and regulation codes. For example, the ASME Boiler and Pressure Vessel Code is a standard providing an array of guidelines and directives to ensure compliance of the boilers and other pressure vessels with safety, design and security standards.[5 -
Historically, boilers were a source of many serious injuries and property destruction due to badly understood engineering principles. Thin and brittle steel shells can rupture, while welded or riveted seams could open up poorly, leading to a violent eruption of the pressurized vapor. When water is converted to vapor it expands to over 1,000 times its original volume and travels down vapor pipes at over 100 kilometres per hour. As a result of this, vapor is a superb way of moving energy and heat around a site from a central boiler house to where it is necessary, but without the right boiler give food to water treatment, a steam-raising herb are affected from level formation and corrosion. At best, this increases energy costs and can result in poor quality vapor, reduced efficiency, shorter plant life and unreliable procedure. At worst, it can lead to catastrophic failure and loss of life. Collapsed or dislodged boiler tubes can also spray scalding-hot vapor and smoke from the air intake and firing chute, injuring the firemen who insert the coal into the open fire chamber. Extremely large boilers providing a huge selection of horsepower to use factories can potentially demolish entire buildings.[6 -
A boiler which has a loss of give food to water and it is permitted to boil dry out can be hugely dangerous. If give food to drinking water is sent into the unfilled boiler then, the small cascade of inbound drinking water instantly boils on connection with the superheated metallic shell and leads to a violent explosion that cannot be managed even by security steam valves. Draining of the boiler can also happen if a leak occurs in the steam source lines that is larger than the make-up drinking water source could replace. The Hartford Loop was created in 1919 by the Hartford Steam Boiler and INSURANCE PROVIDER as a method to assist in preventing this condition from occurring, and thus reduce their insurance statements.[7 - [8 -
Superheated steam boiler
A superheated boiler on a steam locomotive. Main article: Superheater Most boilers produce steam to be utilized at saturation heat; that is, saturated steam. Superheated steam boilers vaporize the water and then further temperature the vapor in a superheater. This provides vapor at higher temperature, but can decrease the overall thermal efficiency of the vapor generating plant because the higher steam temp requires a higher flue gas exhaust heat.[citation needed - There are several ways to circumvent this problem, 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. There are benefits to superheated steam that may, and often will, increase overall efficiency of both vapor generation and its own utilization: gains in input temperatures to a turbine should outweigh any cost in additional boiler problem and expense. There can also be practical limitations in using damp steam, 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 high pressure and temperature can cause serious, instantaneous harm to anyone in its path. Since the escaping steam will at first be completely superheated vapor, detection can be difficult, although the extreme heat and sound from such a leak clearly indicates its presence.
Superheater procedure 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 route in the boiler furnace. The heat range in this area is between 1 typically,300 and 1,600 °C (2,372 and 2,912 °F). Some superheaters are radiant type; that is, they absorb heat by radiation. Others are convection type, absorbing high temperature from a fluid. Some are a combination of the two types. Through either method, the extreme heat in the flue gas path will also temperature the superheater vapor piping and the vapor within. While the heat range of the vapor in the superheater rises, 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 avoid damage 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 used for the production of electric power frequently. 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 no generation of vapor bubbles within water, because the pressure is above the critical pressure point of which vapor bubbles can develop. As the fluid expands through the turbine phases, its thermodynamic state drops below the critical point as it does work turning the turbine which converts the electrical generator that power is ultimately extracted. The fluid at that point may be considered a mixture of steam and liquid droplets as it passes in to the condenser. This results in less fuel use and for that reason less greenhouse gas production slightly. The term "boiler" should not be used for a supercritical pressure vapor generator, as no "boiling" occurs in this product. Boiler Repairs Seven Sisters, N15, Boiler Breakdown Emergency Service http://boiler-repairs-seven-sisters.co.uk - Click here!.. Accessories Boiler accessories and fittings Pressuretrols to regulate the steam pressure in the boiler. Boilers generally have 2 or 3 3 pressuretrols: a manual-reset pressuretrol, which functions as a safety by setting top of the limit of steam pressure, the operating pressuretrol, which handles when the boiler fires to keep up pressure, and for boilers outfitted with a modulating burner, a modulating pressuretrol which controls the amount of fire. Protection valve: It is utilized to relieve pressure and stop possible explosion of the boiler. Water level indicators: They show the operator the amount of liquid in the boiler, also called a view glass, water measure or drinking water column. Bottom level blowdown valves: They offer a way for removing solid particulates that condense and rest on underneath of a boiler. As the name implies, this valve is usually located directly on the bottom of the boiler, and is occasionally opened to use the pressure in the boiler to force 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 lead to foaming and cause drinking water droplets to be transported over with the vapor - a condition known as priming. Blowdown is often used to monitor the chemistry of the boiler water also. Trycock: a type of valve that is often use to manually check a water level in a tank. Most entirely on a water boiler commonly. Flash container: High-pressure blowdown enters this vessel where in fact the vapor can 'flash' safely and become found in a low-pressure system or be vented to atmosphere while the ambient pressure blowdown flows to drain. Automatic blowdown/constant heat recovery system: This technique allows the boiler to blowdown only once make-up water is flowing to the boiler, thereby transferring the utmost amount of heat possible from the blowdown to the make-up water. No flash tank is normally needed as the blowdown discharged is near to the temperature of the make-up water. Hand holes: They may be steel plates installed in openings in "header" to allow for inspections & installation of pipes and inspection of internal surfaces. Vapor drum internals, a series of display, scrubber & cans (cyclone separators). Low-water cutoff: It really is a mechanical means (usually a float switch) that is used to turn off the burner or shut off fuel to the boiler to prevent it from working once the water runs below a certain point. If a boiler is "dry-fired" (burnt without drinking water in it) it can cause rupture or catastrophic failing. Surface blowdown range: It offers a means for removing foam or other light-weight non-condensible substances that have a tendency to float on top of water inside the boiler. Circulating pump: It is designed to circulate drinking water back again to the boiler after they have expelled a few of its heat. Feedwater check valve or clack valve: A non-return stop valve in the feedwater collection. This may be fitted to the relative aspect of the boiler, just below water level, or to the very best of the boiler.[10 - Top feed: Within this design for feedwater injection, the water is fed to the very best of the boiler. This can reduce boiler fatigue caused by thermal stress. By spraying the feedwater over some trays the water is quickly heated which can reduce limescale. Desuperheater tubes or bundles: Some pipes or bundles of pipes in the water drum or the steam drum designed to cool superheated vapor, in order to provide auxiliary equipment that will not need, or may be damaged by, dry out steam. Chemical 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 can be used on multiple boiler installations. Combustion accessories Gas oil system:gasoline 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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