Boiler Repairs Abbey Wood, SE2, Boiler Breakdown Emergency Service
DATEF2018/01/09(Tue) 17:41 No.3
A boiler is a closed vessel where water or other fluid is heated. The fluid will not boil. (In THE UNITED STATES, the word "furnace" is generally used if the purpose is never to boil the fluid.) The heated or vaporized liquid exits the boiler for use in various processes or heating applications,[1 - [2 - including water heating, central heating system, boiler-based power era, cooking food, and sanitation.
The pressure vessel of the boiler is usually made of steel (or alloy steel), or of wrought iron historically. Stainless steel, of the austenitic types especially, is not found in wetted elements of boilers credited to corrosion and stress corrosion cracking.[3 - However, ferritic stainless is often used in superheater sections that won't 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 - 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 (especially for steam 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 steam", the only materials used for boilermaking was the best 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 own suitability for high-reliability use in critical applications, such as high-pressure boilers. In the 20th century, design practice moved towards the use of steel instead, which is stronger and cheaper, with welded construction, which is quicker and requires less labour. It should be mentioned, however, that wrought iron boilers corrode much slower than their modern-day metal counterparts, and are less vunerable to localized stress-corrosion and pitting. This makes the durability of older wrought-iron boilers much superior to those of welded steel boilers.
Cast iron might be used 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 hot water usually, not steam, and so they run at low pressure and try to avoid boiling. The brittleness of cast iron helps it be impractical for high-pressure vapor boilers.
Boiler Repairs Abbey Wood, SE2, Boiler Breakdown Emergency Service http://boiler-repairs-abbey-wood.co.uk - Click here!..
The foundation of heating for a boiler is combustion of some of several fuels, such as wood, coal, oil, or natural gas. Electric vapor boilers use resistance- or immersion-type heating elements. Nuclear fission can be used as a heat source for producing steam also, either straight (BWR) or, generally, in specialised heat exchangers called "vapor generators" (PWR). Heat recovery steam generators (HRSGs) use heat rejected from other processes such as gas turbine.
there are two solutions to gauge the boiler efficiency 1) direct method 2) indirect method
Direct method -immediate approach to boiler efficiency test is more useful or even more common
boiler efficiency =Q*((Hg-Hf)/q)*(GCV *100 ) Q =Total vapor movement Hg= Enthalpy of saturated steam in k cal/kg Hf =Enthalpy of give food to water in kcal/kg q= quantity 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 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" where a fire heats a partially filled drinking water pot from below. 18th century Haycock boilers produced and stored large volumes of very low-pressure steam generally, often barely 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 little volume still left above to support the vapor (steam space). This is the kind of boiler used in all steam locomotives nearly. Heat source is inside a furnace or firebox that has to be held 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 a fire-tube which lengthens the road of the hot gases, thus augmenting the heating surface which may be further increased by making the gases reverse direction through a second parallel pipe or a bundle of multiple pipes (two-pass or return flue boiler); additionally the gases may be studied along the sides and then under the boiler through flues (3-pass 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 improves heat transfer. Fire-tube boilers have a comparatively low rate of vapor creation usually, but high vapor storage capacity. Fire-tube boilers burn off solid fuels mostly, but are easily adaptable to people of the liquid or gas variety.
Diagram of the water-tube boiler.
Water-tube boiler: In this kind, 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 the top ones water and steam; in other situations, such as a mono-tube boiler, water is circulated by a pump through a succession of coils. This type generally gives high vapor creation rates, but less storage space capacity than the above mentioned. Water tube boilers can be made to exploit any heat source and tend to be preferred in high-pressure applications since the high-pressure drinking water/steam is contained within small size pipes which can withstand the pressure with a thinner wall structure.
Flash boiler: A flash boiler is a specialized type of water-tube boiler where pipes are close collectively and drinking 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 pipe is held so hot that water feed is quickly flashed into steam and superheated. Flash boilers got some use in cars in the 19th century which 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 mixed in the following manner: the firebox consists of an assembly of water tubes, called thermic siphons. The gases pass through a conventional firetube boiler then. Water-tube fireboxes were installed in many Hungarian locomotives,[citation needed - but have fulfilled with little success in other countries.
Sectional boiler. Within a solid iron sectional boiler, sometimes called a "pork chop boiler" water is included inside ensemble iron areas.[citation needed - These areas are assembled on site to generate the finished boiler.
See also: Boiler explosion
To define and secure boilers safely, some professional specialized organizations like the American Society of Mechanical Technicians (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, security and design standards.[5 -
Historically, boilers were a source of 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 start poorly, leading to a violent eruption of the pressurized vapor. When drinking water is converted to 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 superb way of moving energy and warmth around a niche site from a central boiler house to where it is needed, but without the right boiler feed water treatment, a steam-raising vegetable will suffer from range formation and corrosion. At best, this raises energy costs and can result in poor quality steam, 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 out of the air intake and firing chute, injuring the firemen who fill the coal into the open fire chamber. Extremely large boilers providing hundreds of horsepower to use factories could demolish entire structures.[6 -
A boiler that has a loss of give food to water and is permitted to boil dry can be extremely dangerous. If nourish drinking water is then sent into the bare boiler, the small cascade of inbound water instantly boils on connection with the superheated metallic shell and leads to a violent explosion that cannot be controlled even by basic safety steam 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 supply could replace. The Hartford Loop was developed in 1919 by the Hartford Vapor Boiler and Insurance Company as a method to help prevent this problem from happening, and thereby reduce their insurance claims.[7 - [8 -
Superheated steam boiler
A superheated boiler on a steam locomotive.
Main article: Superheater
Most boilers produce steam to be utilized at saturation temperatures; that is, saturated vapor. Superheated vapor boilers vaporize the water and then further temperature the steam in a superheater. This provides steam at much higher heat range, but can reduce the overall thermal efficiency of the vapor generating vegetable because the higher vapor temperatures takes a higher flue gas exhaust temp.[citation needed - There are several ways to circumvent this issue, by giving an economizer that heats the give food to water typically, a combustion air heater in the hot flue gas exhaust route, or both. There are advantages to superheated vapor that may, and often will, increase overall efficiency of both vapor generation and its utilization: increases in input temp to a turbine should outweigh any cost in additional boiler complication and expense. There could be useful restrictions in using damp vapor also, 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 at first be completely superheated vapor, detection can be difficult, although the intense heat and sound from such a leak obviously indicates its presence.
Superheater procedure is similar to that of the coils on an air conditioning unit, although for a different purpose. The steam piping is directed through the flue gas path in the boiler furnace. The temperatures in this field is between 1 typically,300 and 1,600 C (2,372 and 2,912 F). Some superheaters are radiant type; that is, they absorb temperature by rays. Others are convection type, absorbing warmth from a fluid. Some are a mixture of both types. Through either method, the extreme temperature in the flue gas path will also high temperature the superheater steam piping and the steam within. While the temperature of the steam in the superheater increases, the pressure of the vapor does 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 herb.
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 steam 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 liquid is neither water nor gas but a super-critical liquid. There is absolutely no era of vapor bubbles within the water, because the pressure is above the critical pressure point of which vapor bubbles can form. As the liquid expands through the turbine levels, its thermodynamic state drops below the critical point as it does work turning the turbine which converts the electrical generator from which power is ultimately extracted. The fluid at that point may be a mixture of vapor and liquid droplets as it goes by in to 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 product.
Boiler Repairs Abbey Wood, SE2, Boiler Breakdown Emergency Service http://boiler-repairs-abbey-wood.co.uk - Click here...
Boiler fittings and accessories
Pressuretrols to regulate 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 the top limit of vapor pressure, the working pressuretrol, which settings when the boiler fires to keep up pressure, and 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 prevent possible explosion of the boiler.
Water level indications: They show the operator the amount of fluid in the boiler, known as a sight cup also, water gauge or drinking water column.
Bottom blowdown valves: They provide a way for removing solid particulates that condense and lie on underneath of the boiler. As the name implies, this valve is situated straight on underneath of the boiler usually, and is sometimes opened to use the pressure in the boiler to drive these particulates out.
Continuous blowdown valve: This enables a small quantity of water to escape continuously. Its purpose is to prevent 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 - 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 liquid level in a container. Most entirely on a drinking water boiler commonly.
Flash container: High-pressure blowdown enters this vessel where in fact the steam can 'flash' safely and be found in a low-pressure system or be vented to atmosphere while the ambient pressure blowdown moves to drain.
Automatic blowdown/constant heat recovery system: This system 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 makeup water. No flash container is normally needed as the blowdown discharged is close to the temp of the make-up water.
Hand openings: They may be metal plates installed in openings in "header" to permit for inspections & installing pipes and inspection of internal surfaces.
Vapor drum internals, some screen, scrubber & cans (cyclone separators).
Low-water cutoff: It really is a mechanical means (usually a float switch) that can be used to turn from the burner or shut off fuel to the boiler to avoid it from working once the 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 line: It offers a means for removing foam or other lightweight non-condensible chemicals that have a tendency to float together with water inside the boiler.
Circulating pump: It is designed 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 range. This may be fitted to the medial side of the boiler, just below water level, or to the top of the boiler.[10 -
Top give food to: Within this design for feedwater injection, the water is fed to the top of the boiler. This may reduce boiler exhaustion caused by thermal stress. By spraying the feedwater over a series of trays the water is quickly warmed which can reduce limescale.
Desuperheater tubes or bundles: A series of pipes or bundles of pipes in water drum or the vapor drum made to cool superheated steam, in order to provide auxiliary equipment that will not need, or may be damaged by, dry out vapor.
Chemical substance injection line: A link with add chemicals for controlling feedwater pH.
Main steam stop valve:
Main steam stop/check valve: It is utilized on multiple boiler installations.
Gas oil system:gas oil heaters
Other essential items
Inspectors test pressure measure attachment: