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ConradOript (site web) Le 29/11/2017

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ConradOript (site web) Le 28/11/2017

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RomanRow (site web) Le 28/11/2017

Минут пять просматривал содержимое интернет, неожиданно к своему удивлению обнаружил неплохой вебсайт. Посмотрите: купить кредитную карту с пин-кодом . Для меня данный ресурс показался весьма важным. Всего доброго!

LeonardVam Le 28/11/2017

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Jamesriz (site web) Le 28/11/2017

A boiler is a closed vessel where drinking water or other fluid is heated. The fluid will not boil. (In THE UNITED STATES, the term "furnace" is normally used if the purpose is never to boil the liquid.) The heated or vaporized liquid exits the boiler for use in a variety of heating system or procedures applications,[1][2] including water heating, central heating, boiler-based power generation, cooking food, and sanitation.

Materials
The pressure vessel of a boiler is usually made of steel (or alloy steel), or of wrought iron historically. Stainless steel, of the austenitic types especially, is not used in wetted parts of boilers thanks to stress and corrosion corrosion cracking.[3] However, ferritic stainless steel is often found in superheater sections that won't come in contact with 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]
https://en.wikipedia.org/wiki/Boiler
In live steam models, copper or brass is often used because it is more easily fabricated in smaller size boilers. Historically, copper was often used for fireboxes (especially for steam 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 metal) are used instead.

For much of the Victorian "age of steam", the only material used for boilermaking was the best 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 own suitability for high-reliability use in critical applications, such as high-pressure boilers. In the 20th century, design practice instead relocated towards the use of metal, which is stronger and cheaper, with welded building, 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 durability of older wrought-iron boilers much more advanced than those of welded metal boilers.

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

Boiler efficiency
there are two methods to measure 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 give food to water in kcal/kg q= quantity 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 need a following parameter like

Ultimate analysis of energy (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 gas in kcal/kg
ash percentage in combustible fuel
GCV of ash in kcal/kg
Configurations
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 volumes of very low-pressure vapor generally, barely above that of the atmosphere often. These could burn wood or frequently, coal. Efficiency was suprisingly low.
Flued boiler with a couple of large flues-an early forerunner or kind of fire-tube boiler.

Diagram of a fire-tube boiler
Fire-tube boiler: Here, water partially fills a boiler barrel with a little volume still left above to support the steam (vapor space). This is the kind of boiler used in almost all steam locomotives. The heat source is inside a furnace or firebox that has to be kept permanently surrounded by water in order to maintain the temp 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 system surface which can be further increased by causing the gases reverse direction through another parallel pipe or a lot of money of multiple pipes (two-pass or return flue boiler); additionally the gases may be taken along the sides and then beneath the boiler through flues (3-move boiler). In case of a locomotive-type boiler, a boiler barrel extends from the firebox and the hot gases go through a lot of money of fire pipes inside the barrel which greatly increases the heating system surface in comparison to a single pipe and further enhances heat transfer. Fire-tube boilers have a comparatively low rate of vapor production usually, but high vapor storage capacity. Fire-tube boilers mostly burn solid fuels, but are easily adjustable to people of the liquid or gas variety.

Diagram of a water-tube boiler.
Water-tube boiler: In this type, tubes filled with drinking water are arranged inside a furnace in several possible configurations. Often the water pipes connect large drums, the lower ones filled with water and top of the ones vapor and drinking water; in other situations, such as a mono-tube boiler, drinking water is circulated by a pump through a succession of coils. This type generally gives high vapor production rates, but less storage space capacity than the above. Water tube boilers can be made to exploit any temperature source and are generally preferred in high-pressure applications since the high-pressure water/steam is included within small size pipes which can withstand the pressure with a thinner wall structure.
Flash boiler: A flash boiler is a specialized kind of water-tube boiler in which pipes are close collectively and water is pumped through them. A flash boiler differs from the type of mono-tube steam 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 steam and superheated. Flash boilers had some use in automobiles in the 19th century which use continued into 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 combined in the following manner: the firebox includes 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 met with little success in other countries.
Sectional boiler. Within a ensemble iron sectional boiler, sometimes called a "pork chop boiler" water is contained inside cast iron areas.[citation needed] These areas are assembled on site to produce the finished boiler.
Safety
See also: Boiler explosion
To define and secure boilers safely, some professional specialized organizations such as the American Society of Mechanical Technicians (ASME) develop requirements and regulation rules. For instance, 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 way to obtain many serious injuries and property destruction due to poorly understood engineering principles. Thin and brittle metal shells can rupture, while welded or riveted seams could open up badly, resulting in 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. 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 feed water treatment, a steam-raising plant are affected from level corrosion and formation. At best, this increases 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 failure of life. Collapsed or dislodged boiler pipes can also squirt scalding-hot steam and smoke out of the air intake and firing chute, injuring the firemen who insert the coal in to the fire chamber. Extremely large boilers providing a huge selection of horsepower to operate factories can potentially demolish entire structures.[6]

A boiler that has a loss of feed water and is permitted to boil dry can be extremely dangerous. If give food to drinking water is then sent into the vacant boiler, the tiny cascade of inbound water instantly boils on contact with the superheated metallic shell and leads to a violent explosion that can't be controlled even by basic safety 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 Vapor Boiler and Insurance Company as a method to assist in preventing this condition from happening, and thereby 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 used at saturation temp; that is, saturated steam. Superheated steam boilers vaporize the water and then further temperature the steam in a superheater. This provides vapor at much higher temp, but can decrease the overall thermal efficiency of the vapor generating herb because the higher steam heat range requires a higher flue gas exhaust temp.[citation needed] There are several ways to circumvent this problem, typically by giving an economizer that heats the give food to drinking water, a combustion air heater 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 utilization: benefits in input temperatures to a turbine should outweigh any cost in additional boiler problem and expense. There could be practical limitations in using moist vapor also, as entrained condensation droplets will harm turbine blades.

Superheated steam presents unique safety concerns because, if any system component fails and allows steam to flee, the temperature and pressure 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 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 steam piping is directed through the flue gas route in the boiler furnace. The heat range in this area is normally between 1,300 and 1,600 °C (2,372 and 2,912 °F). Some superheaters are radiant type; that is, they absorb high temperature by radiation. Others are convection type, absorbing temperature from a fluid. Some are a combination of the two types. Through either method, the extreme warmth in the flue gas route will also heat the superheater steam piping and the vapor within. While the temperature of the vapor in the superheater rises, the pressure of the vapor 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 avoid harm to the turbine blading and associated piping.

Supercritical steam generator

Boiler for a power vegetable.
Main article: Supercritical steam generator
Supercritical steam generators are frequently used for the production of electric power. They operate at supercritical pressure. As opposed to a "subcritical boiler", a supercritical steam generator operates at such a high pressure (over 3,200 psi or 22 MPa) that the physical turbulence that characterizes boiling ceases that occurs; 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 at which vapor bubbles can form. As the liquid expands through the turbine stages, its thermodynamic state drops below the critical point as it does work turning the turbine which converts the power generator that power is eventually extracted. The liquid at that point may be considered a mix of vapor and liquid droplets as it passes in to the condenser. This results in less fuel use and therefore less greenhouse gas production slightly. The word "boiler" should not be used for a supercritical pressure vapor generator, as no "boiling" occurs in this product.
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Accessories
Boiler fittings and accessories
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 protection by setting top of the limit of vapor pressure, the working pressuretrol, which settings when the boiler fires to maintain pressure, and for boilers outfitted with a modulating burner, a modulating pressuretrol which settings the amount of fire.
Protection valve: It is used to alleviate 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 sight glass, water measure or water column.
Bottom level blowdown valves: They provide a means for removing solid particulates that condense and lie on the bottom of the boiler. As the name indicates, 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 quantity of water to escape continuously. Its purpose is to prevent water in the boiler becoming saturated with dissolved salts. Saturation would lead to foaming and cause drinking water droplets to be carried over with the steam - a disorder 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 found on a water boiler commonly.
Flash container: High-pressure blowdown enters this vessel where the steam can 'flash' safely and become used in a low-pressure system or be vented to atmosphere as the ambient pressure blowdown moves to drain.
Automatic blowdown/continuous heat recovery system: This system allows the boiler to blowdown only once make-up water is moving 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 close to the temperatures of the make-up water.
Hand holes: They are metal plates installed in openings in "header" to allow for inspections & installing tubes and inspection of internal surfaces.
Steam drum internals, a series of display, scrubber & cans (cyclone separators).
Low-water cutoff: It is a mechanical means (usually a float switch) that is utilized to turn from the burner or shut down gas to the boiler to prevent it from running once the drinking water goes 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 collection: It offers a way for removing foam or other light-weight non-condensible substances that have a tendency to float together with the water inside the boiler.
Circulating pump: It is made to circulate drinking water back to the boiler after it has expelled a few of its heat.
Feedwater check valve or clack valve: A non-return stop valve in the feedwater collection. This may be suited to the relative part of the boiler, below water level just, or to the top of the boiler.[10]
Top give food to: With this design for feedwater injection, water is fed to the top of the boiler. This can reduce boiler exhaustion triggered by thermal stress. By spraying the feedwater over a series of trays the water is quickly warmed and this can reduce limescale.
Desuperheater tubes or bundles: Some tubes or bundles of pipes in water drum or the steam drum designed to cool superheated vapor, in order to supply auxiliary equipment that will not need, or may be damaged by, dry out steam.
Chemical substance injection line: A link with add chemicals for controlling feedwater pH.
Steam accessories
Main vapor stop valve:
Steam traps:
Main steam stop/check valve: It is utilized on multiple boiler installations.
Combustion accessories
Energy 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 plate:
Registration plate: