blog.voyageprague.com

6453 комментарии

• Ссылка на комментарий 27.11.2017 23:58 отправлено Jamesgek

  A boiler is a closed vessel where drinking water or other fluid is heated. The liquid will not always boil. (In North America, the word "furnace" is normally used if the purpose is not to boil the fluid.) The warmed or vaporized fluid exits the boiler for use in various heating or processes applications,[1 - [2 - including water heating, central heating system, boiler-based power era, cooking food, and sanitation.
  
  Materials
  The pressure vessel of a boiler is usually manufactured from steel (or alloy steel), or historically of wrought iron. Stainless steel, especially of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion breaking.[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 creation 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 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 much of the Victorian "age of vapor", the only material used for boilermaking was the highest grade of wrought iron, with set up by rivetting. This iron was obtained from specialist ironworks, such as at Cleator Moor (UK), mentioned 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 shifted towards the use of steel instead, which is more powerful and cheaper, with welded structure, 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 susceptible to localized stress-corrosion and pitting. This makes the durability of old wrought-iron boilers considerably superior to those of welded steel boilers.
  
  Cast iron can be utilized for the heating vessel of domestic drinking water heaters. Although such heaters are usually termed "boilers" in a few countries, their purpose is to produce warm water usually, not steam, and so they run at low pressure and stay away from boiling. The brittleness of cast iron makes it impractical for high-pressure steam boilers.
  Boiler Repairs Penge, Anerley, SE20, Boiler Breakdown Emergency Service http://boiler-repairs-penge.co.uk - Show more!
  Energy
  The source of heat for a boiler is combustion of some of several fuels, such as wood, coal, oil, or 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 directly (BWR) or, generally, in specialised heat exchangers called "vapor generators" (PWR). 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 method of boiler efficiency test is more useful or even more common
  
  boiler efficiency =Q*((Hg-Hf)/q)*(GCV *100 ) Q =Total steam circulation Hg= Enthalpy of saturated steam in k cal/kg Hf =Enthalpy of feed water in kcal/kg q= level of energy 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 gas 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" in which a fireplace heats a partially filled water box from below. 18th century Haycock boilers produced and stored large volumes of very low-pressure steam generally, often hardly above that of the atmosphere. These could burn wood or frequently, coal. Efficiency was suprisingly low.
  Flued boiler with one or two large flues-an early forerunner or type of fire-tube boiler.
  
  Diagram of a 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 (vapor space). This is the type of boiler used in all steam locomotives nearly. The heat source is in the furnace or firebox that has to be kept completely surrounded by the water in order to maintain 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 causing the gases invert direction through another parallel tube or a bundle of multiple pipes (two-pass or come back 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 expands from the firebox and the hot gases go through a bundle of fire pipes inside the barrel which greatly escalates the heating 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 mainly burn off 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 kind, tubes filled up with water are arranged in the furnace in a genuine quantity of possible configurations. Usually the water tubes connect large drums, the lower ones comprising water and the top ones vapor and drinking water; in other instances, such as a mono-tube boiler, drinking water is circulated by a pump through a succession of coils. This type provides high vapor production rates generally, but less storage space capacity than the above mentioned. Water tube boilers can be made to exploit any temperature source and are generally preferred in high-pressure applications because the high-pressure drinking water/steam is contained 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 pipes are close jointly and water is pumped through them. A flash boiler differs from the type of mono-tube steam generator where the pipe is permanently filled with water. Super fast boiler, the pipe is held so hot that water feed is quickly flashed into steam and superheated. Flash boilers had 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 both above types have been mixed in the next manner: the firebox includes an assembly of water pipes, called thermic siphons. The gases then pass through a conventional firetube boiler. 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 ensemble iron sections.[citation needed - These sections are assembled on site to make 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 Technical engineers (ASME) develop criteria and regulation rules. 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 security, design and security standards.[5 -
  
  Historically, boilers were a way to obtain many serious injuries and property destruction as a consequence to badly understood engineering principles. Thin and brittle metal shells can rupture, while welded or riveted seams could start poorly, resulting in a violent eruption of the pressurized steam. When water is changed into vapor it expands to over 1,000 times its original quantity and moves down vapor pipes at over 100 kilometres per hour. Because of this, vapor is a superb way of moving energy and high temperature around a site from a central boiler house to where it is needed, but with no right boiler give food to water treatment, a steam-raising seed are affected from scale development and corrosion. At best, this increases energy costs and can lead to poor quality steam, reduced efficiency, shorter plant life and unreliable operation. At worst, it can result in catastrophic failure and loss of life. Collapsed or dislodged boiler pipes can also aerosol scalding-hot steam and smoke from the air intake and firing chute, injuring the firemen who insert the coal in to the fireplace 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 drinking water and is permitted to boil dry can be extremely dangerous. If feed water is then sent in to the bare boiler, the small cascade of inbound water instantly boils on contact with the superheated steel 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 steam source lines that is larger than the make-up water supply could replace. The Hartford Loop was invented in 1919 by the Hartford Steam Boiler and Insurance Company as a strategy to help prevent this condition from occurring, and therefore reduce their insurance promises.[7 - [8 -
  
  Superheated steam boiler
  
  A superheated boiler on a steam locomotive.
  Main article: Superheater
  Most boilers produce vapor to be used at saturation temperature; that is, saturated vapor. Superheated steam boilers vaporize the water and then further high temperature the steam in a superheater. This provides vapor at higher heat range, but can reduce the overall thermal efficiency of the steam generating place because the higher steam heat takes a higher flue gas exhaust heat range.[citation needed - There are several ways to circumvent this problem, typically by providing an economizer that heats the feed water, a combustion air heater 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 steam generation and its utilization: benefits in input temperatures to a turbine should outweigh any cost in additional boiler complication and expense. There could be practical restrictions in using wet steam 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 escape, 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 extreme heat and sound from such a leak clearly indicates its presence.
  
  Superheater procedure is similar to that of the coils on an air conditioning unit, although for a different purpose. The vapor piping is directed through the flue gas path in the boiler furnace. The temperature 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 warmth by rays. Others are convection type, absorbing heat from a fluid. Some are a mixture of the two types. Through either method, the extreme heat in the flue gas path will also heat the superheater steam piping and the steam within. While the heat range of the vapor in the superheater rises, the pressure of the vapor will 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 damage to the turbine blading and associated piping.
  
  Supercritical steam generator
  
  Boiler for a charged power seed.
  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 higher pressure (over 3,200 psi or 22 MPa) that the physical turbulence that characterizes boiling ceases to occur; the fluid is neither liquid nor gas but a super-critical liquid. There is 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 phases, its thermodynamic state drops below the critical point as it does work turning the turbine which changes the power generator that 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 leads to less fuel use and for that reason less greenhouse gas production slightly. The word "boiler" shouldn't be used for a supercritical pressure vapor generator, as no "boiling" occurs in this device.
  Boiler Repairs Penge, Anerley, SE20, Boiler Breakdown Emergency Service http://boiler-repairs-penge.co.uk - Boiler Repairs Penge, Anerley, SE20, Boiler Breakdown Emergency Service>>>
  Accessories
  Boiler accessories and fittings
  Pressuretrols to control the steam pressure in the boiler. Boilers generally have two or three 3 pressuretrols: a manual-reset pressuretrol, which functions as a security by setting top of the limit of vapor pressure, the working pressuretrol, which controls when the boiler fires to keep pressure, as well as for boilers equipped with a modulating burner, a modulating pressuretrol which settings the amount of fire.
  Basic safety valve: It is utilized to relieve pressure and stop possible explosion of the boiler.
  Water level indicators: They show the operator the level of fluid in the boiler, also known as a view glass, water measure or water column.
  Bottom level blowdown valves: They provide a way for removing solid particulates that condense and lie on the bottom of a boiler. As the name implies, this valve is located straight on underneath of the boiler usually, and is occasionally opened up to use the pressure in the boiler to push these particulates out.
  Continuous blowdown valve: This enables a small level of water to flee continuously. Its purpose is to avoid 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 vapor - an ailment 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 commonly found on a drinking water boiler.
  Flash container: High-pressure blowdown enters this vessel where in fact the vapor can 'flash' safely and be used in a low-pressure system or be vented to atmosphere while the ambient pressure blowdown moves to drain.
  Automatic blowdown/continuous heat recovery system: This system allows the boiler to blowdown only when makeup water is flowing to the boiler, thereby transferring the maximum amount of heat possible from the blowdown to the make-up water. No flash tank is normally needed as the blowdown discharged is close to the heat range of the make-up water.
  Hand holes: They may be metal plates installed in openings in "header" to allow for inspections & installing tubes and inspection of inner surfaces.
  Steam drum internals, a series of display, scrubber & cans (cyclone separators).
  Low-water cutoff: It is a mechanical means (usually a float change) that is utilized to turn off the burner or shut down gas to the boiler to prevent it from working once the water runs below a certain point. If a boiler is "dry-fired" (burned without drinking water in it) it can cause rupture or catastrophic failure.
  Surface blowdown collection: It provides a way 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 made to circulate water back again 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 range. This may be fitted to the relative part of the boiler, just below water level, or to the top of the boiler.[10 -
  Top give food to: In this design for feedwater injection, water is fed to the very best of the boiler. This may reduce boiler exhaustion caused by thermal stress. By spraying the feedwater over a series of trays water is quickly warmed which can reduce limescale.
  Desuperheater pipes 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 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 vapor stop/check valve: It is utilized 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 measure attachment:
  Name plate:
  Registration dish:

  Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript
  
• Ссылка на комментарий 27.11.2017 23:42 отправлено Online Essay Help

  essay buying easy essay help buy essay buy essay papers

  Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript
  
• Ссылка на комментарий 27.11.2017 23:27 отправлено Yakunpep

  504 Gateway Time-out
  
  
  unsusa ArriceCruro Snisefreeree
  Seantato appoxdach EasetaCoact
  Prunse itene Floossy
  Arrengatt Analorgo sepImmummambcic

  Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript
  
• Ссылка на комментарий 27.11.2017 22:58 отправлено Joehap

  instant online payday loan example here onlineloans.us.com best cash loans online

  Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript
  
• Ссылка на комментарий 27.11.2017 22:39 отправлено Staci

  voyance caen avis voyance gratuite 100 formule magique voyance voyance en ligne gratuit voyance medium serieux gratuit voyance qui marche vraiment voyance en ligne
  sans attente gratuite voyance en directe voyance carte ordinaire gratuite voyance gratuite sans attente pas cher voyance numerologie gratuite fiabilite
  voyance par telephone consultation voyance tchat de voyance 100 gratuit voyance serieuse pas cher voyance saumur
  49 voyance perpignan et alentours signification carte voyance voyance toulon voyance gitane
  avis voyance par telephone serieuse pas cher magique voyance qui connait un bon site de voyance gratuite voyance audiotel serieuse voyance serieuse par tel site de voyance par telephone
  gratuit voyance pas cher sans attente voyance gratuite tirage tirage carte pour voyance gratuit
  meilleur site de voyance gratuite voyance tarot amour gratuit tchat gratuit voyance en direct jeu de
  tarot voyance gratuit horoscope voyance astrologie voyance gratuite voyance gratuite pour le travail voyance et magie gratuite immediate voyance carte en ligne voyance gratuite tchat travail tarot gratuit voyance tchatche voyance gratuit voyance par sms
  pas cher voyance en ligne tchat gratuit voyance dunkerque voyance gratuite immediate
  sans attente telephone une voyance gratuite par chat voyance le havre site
  de voyance serieux tchatche voyance gratuit oracle voyance gratuite la
  boule voyance

  Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript