A boiler or steam generator is a device used to create steam by applying heat energy to water . Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure (7–2,000 kPa or 1–290 psi ) but, at pressures above this, it is more usual to speak of a steam generator .
55-532: Lidgerwood was a historic American engineering company famous for its boilers , winches , scrapers , hoists and cranes , particularly ones that helped build the Panama Canal . They later built logging yarders and aerial tramways , cable cars or ropeways. Lidgerwood winches had at least two specific railroad maintenance uses, and were used by railroad customers to move railroad freight cars into position for loading and unloading (and to move other cars out of
110-471: A "pork chop boiler" the water is contained inside cast iron sections. These sections are mechanically assembled on site to create the finished boiler. Supercritical steam generators are frequently used for the production of electric power . They operate at supercritical pressure. In contrast to a "subcritical boiler", a supercritical steam generator operates at such a high pressure (over 3,200 psi or 22.06 MPa ) that actual boiling ceases to occur,
165-401: A building. The amount of water vapor that can be stored in the air can be increased simply by increasing the temperature. However, this can be a double edged sword as most condensation in the home occurs when warm, moisture heavy air comes into contact with a cool surface. As the air is cooled, it can no longer hold as much water vapor. This leads to deposition of water on the cool surface. This
220-409: A cylindrical water tank around 27 feet (8.2 m) long and 7 feet (2.1 m) in diameter, and had a coal fire grate placed at one end of a single cylindrical tube about three feet wide which passed longitudinally inside the tank. The fire was tended from one end and the hot gases from it travelled along the tube and out of the other end, to be circulated back along flues running along the outside then
275-461: A given quantity of water by superheating it. As the fire is burning at a much higher temperature than the saturated steam it produces, far more heat can be transferred to the once-formed steam by superheating it and turning the water droplets suspended therein into more steam and greatly reducing water consumption. The superheater works like coils on an air conditioning unit, however to a different end. The steam piping (with steam flowing through it)
330-446: A great deal of heat wasted up the chimney . In later models, notably by John Smeaton , heating surface was considerably increased by making the gases heat the boiler sides, passing through a flue . Smeaton further lengthened the path of the gases by means of a spiral labyrinth flue beneath the boiler. These under-fired boilers were used in various forms throughout the 18th century. Some were of round section (haycock). A longer version on
385-424: A greater temperature gradient, which helps reduce the potential to form condensation . Any remaining heat in the combustion gases can then either be evacuated or made to pass through an economiser , the role of which is to warm the feed water before it reaches the boiler. For the first Newcomen engine of 1712, the boiler was little more than large brewer's kettle installed beneath the power cylinder. Because
440-404: A large number of bends and sometimes fins to maximize the surface area. This type of boiler is generally preferred in high pressure applications since the high pressure water/steam is contained within narrow pipes which can contain the pressure with a thinner wall. It can however be susceptible to damage by vibration in surface transport appliances. In a cast iron sectional boiler, sometimes called
495-427: A longitudinal welded seam. Welded construction for locomotive boilers was extremely slow to take hold. Once-through monotubular water tube boilers as used by Doble, Lamont and Pritchard are capable of withstanding considerable pressure and of releasing it without danger of explosion. The source of heat for a boiler is combustion of any of several fuels, such as wood , coal , oil , or natural gas . Nuclear fission
550-428: A rate which can vary according to the pressure above the boiling water. The higher the furnace temperature, the faster the steam production. The saturated steam thus produced can then either be used immediately to produce power via a turbine and alternator , or else may be further superheated to a higher temperature; this notably reduces suspended water content making a given volume of steam produce more work and creates
605-466: A rectangular plan was developed around 1775 by Boulton and Watt (wagon top boiler). This is what is today known as a three-pass boiler, the fire heating the underside, the gases then passing through a central square-section tubular flue and finally around the boiler sides. An early proponent of the cylindrical form was the British engineer John Blakey, who proposed his design in 1774. Another early proponent
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#1732858384387660-499: A single fire tube, at one end of which was placed the fire grate . The gas flow was then reversed into a passage or flue beneath the boiler barrel, then divided to return through side flues to join again at the chimney (Columbian engine boiler). Evans incorporated his cylindrical boiler into several engines, both stationary and mobile. Due to space and weight considerations the latter were one-pass exhausting directly from fire tube to chimney. Another proponent of "strong steam" at that time
715-425: A smaller boiler that forms an integral part of the vehicle; stationary steam engines , industrial installations and power stations will usually have a larger separate steam generating facility connected to the point-of-use by piping. A notable exception is the steam-powered fireless locomotive , where separately-generated steam is transferred to a receiver (tank) on the locomotive. The steam generator or steam boiler
770-523: A supercritical pressure steam generator, as no "boiling" actually occurs in this device. Feed water for boilers needs to be as pure as possible with a minimum of suspended solids and dissolved impurities which cause corrosion , foaming and water carryover . The most common options for demineralization of boiler feedwater are reverse osmosis (RO) and ion exchange (IX). When water is converted to steam it expands in volume 1,600 times and travels down steam pipes at over 25 m/s. Because of this, steam
825-460: A third time beneath the boiler barrel before being expelled into a chimney. This was later improved upon by another 3-pass boiler, the Lancashire boiler which had a pair of furnaces in separate tubes side-by-side. This was an important improvement since each furnace could be stoked at different times, allowing one to be cleaned while the other was operating. Railway locomotive boilers were usually of
880-456: Is a crucial component of distillation , an important laboratory and industrial chemistry application. Because condensation is a naturally occurring phenomenon, it can often be used to generate water in large quantities for human use. Many structures are made solely for the purpose of collecting water from condensation, such as air wells and fog fences . Such systems can often be used to retain soil moisture in areas where active desertification
935-556: Is a good way of moving energy and heat around a site from a central boiler house to where it is needed, but without the right boiler feed water treatment, a steam-raising plant will suffer from scale formation and corrosion. At best, this increases energy costs and can lead to poor quality steam, reduced efficiency, shorter plant life and an operation which is unreliable. At worst, it can lead to catastrophic failure and loss of life. While variations in standards may exist in different countries, stringent legal, testing, training and certification
990-415: Is also used as a heat source for generating steam. Heat recovery steam generators (HRSGs) use the heat rejected from other processes such as gas turbines . In order to create optimum burning characteristics of the fire , air needs to be supplied both through the grate, and above the fire. Most boilers now depend on mechanical draft equipment rather than natural draught . This is because natural draught
1045-435: Is an integral component of a steam engine when considered as a prime mover . However it needs to be treated separately, as to some extent a variety of generator types can be combined with a variety of engine units. A boiler incorporates a firebox or furnace in order to burn the fuel and generate heat . The generated heat is transferred to water to make steam , the process of boiling . This produces saturated steam at
1100-422: Is applied to try to minimize or prevent such occurrences. Failure modes include: The Doble steam car uses a once-through type contra-flow generator, consisting of a continuous tube. The fire here is on top of the coil instead of underneath. Water is pumped into the tube at the bottom and the steam is drawn off at the top. This means that every particle of water and steam must necessarily pass through every part of
1155-422: Is directed through the flue gas path in the boiler furnace. This area typically is between 1,300–1,600 °C (2,372–2,912 °F ). Some superheaters are radiant type (absorb heat by thermal radiation ), others are convection type (absorb heat via a fluid i.e. gas) and some are a combination of the two. So whether by convection or radiation the extreme heat in the boiler furnace/flue gas path will also heat
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#17328583843871210-400: Is impractical to position steam locomotives over a lathe or to remove the wheels for re-profiling (although shop lathes do re-profile dis-mounted drive wheels when the locomotive is already disassembled). Instead, a winch – known colloquially as "The Lidgerwood" on some railroads – would move the locomotive while cutting heads were mounted on brake shoe brackets and forced against the wheels. As
1265-400: Is named " saturated steam ". For example, saturated steam at atmospheric pressure boils at 100 °C (212 °F). Saturated steam taken from the boiler may contain entrained water droplets, however a well designed boiler will supply virtually "dry" saturated steam, with very little entrained water. Continued heating of the saturated steam will bring the steam to a "superheated" state, where
1320-672: Is occurring—so much so that some organizations educate people living in affected areas about water condensers to help them deal effectively with the situation. It is also a crucial process in forming particle tracks in a cloud chamber . In this case, ions produced by an incident particle act as nucleation centers for the condensation of the vapor producing the visible "cloud" trails. Commercial applications of condensation, by consumers as well as industry, include power generation, water desalination, thermal management, refrigeration, and air conditioning. Numerous living beings use water made accessible by condensation. A few examples of these are
1375-417: Is subject to outside air conditions and temperature of flue gases leaving the furnace, as well as chimney height. All these factors make effective draught hard to attain and therefore make mechanical draught equipment much more economical. There are three types of mechanical draught: The next stage in the process is to boil water and make steam. The goal is to make the heat flow as completely as possible from
1430-625: The Australian thorny devil , the darkling beetles of the Namibian coast, and the coast redwoods of the West Coast of the United States . Condensation in building construction is an unwanted phenomenon as it may cause dampness , mold health issues , wood rot , corrosion , weakening of mortar and masonry walls, and energy penalties due to increased heat transfer . To alleviate these issues,
1485-579: The Rainhill trials of 1829 Henry Booth , treasurer of the Liverpool and Manchester Railway suggested to George Stephenson , a scheme for a multi-tube one-pass horizontal boiler made up of two units: a firebox surrounded by water spaces and a boiler barrel consisting of two telescopic rings inside which were mounted 25 copper tubes; the tube bundle occupied much of the water space in the barrel and vastly improved heat transfer . Old George immediately communicated
1540-503: The water cycle . It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere . When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition . Condensation is initiated by the formation of atomic/molecular clusters of that species within its gaseous volume—like rain drop or snow flake formation within clouds —or at
1595-469: The 1-pass type, although in early days, 2-pass "return flue" boilers were common, especially with locomotives built by Timothy Hackworth . A significant step forward came in France in 1828 when Marc Seguin devised a two-pass boiler of which the second pass was formed by a bundle of multiple tubes. A similar design with natural induction used for marine purposes was the popular Scotch marine boiler . Prior to
1650-441: The boiler has no liquid water - steam separation. There is no generation of steam bubbles within the water, because the pressure is above the critical pressure at which steam bubbles can form. It passes below the critical point as it does work in a high-pressure turbine and enters the generator's condenser . This results in slightly less fuel use and therefore less greenhouse gas production. The term "boiler" should not be used for
1705-503: The coil as the fire would be automatically cut off by the temperature. Similar forced circulation generators , such as the Pritchard and Lamont and Velox boilers present the same advantages. Steam boilers are used where steam and hot steam is needed. Hence, steam boilers are used as generators to produce electricity in the energy business. It is also used in rice mills for parboiling and drying. Besides many different application areas in
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1760-435: The contact between such gaseous phase and a liquid or solid surface. In clouds , this can be catalyzed by water-nucleating proteins , produced by atmospheric microbes, which are capable of binding gaseous or liquid water molecules. A few distinct reversibility scenarios emerge here with respect to the nature of the surface. Condensation commonly occurs when a vapor is cooled and/or compressed to its saturation limit when
1815-448: The draft are available for review. The European standards for acceptance test of steam boilers are EN 12952-15 and EN 12953–11. The British standards BS 845-1 and BS 845-2 remain also in use in the UK. Condensation Condensation is the change of the state of matter from the gas phase into the liquid phase , and is the reverse of vaporization . The word most often refers to
1870-406: The engine's power was derived from the vacuum produced by condensation of the steam, the requirement was for large volumes of steam at very low pressure hardly more than 1 psi (6.9 kPa ). The whole boiler was set into brickwork which retained some heat. A voluminous coal fire was lit on a grate beneath the slightly dished pan which gave a very small heating surface; there was therefore
1925-493: The flat cars then the train of flat cars was moved to where the material was to be unloaded and the plow was pulled over the decks, forcing the material laterally off the flat cars where it fell to the embankment. Boiler (power generation) A boiler or steam generator is used wherever a source of steam is required. The form and size depends on the application: mobile steam engines such as steam locomotives , portable engines and steam-powered road vehicles typically use
1980-445: The fuel expended to produce it. Another way to rapidly produce steam is to feed the water under pressure into a tube or tubes surrounded by the combustion gases. The earliest example of this was developed by Goldsworthy Gurney in the late 1820s for use in steam road carriages. This boiler was ultra-compact and light in weight and this arrangement has since become the norm for marine and stationary applications. The tubes frequently have
2035-412: The generator causing an intense circulation which prevents any sediment or scale from forming on the inside of the tube. Water enters the bottom of this tube at the flow rate of 600 feet (183 m) a second with less than two quarts of water in the tube at any one time. As the hot gases pass down between the coils, they gradually cool, as the heat is being absorbed by the water. The last portion of
2090-457: The generator with which the gases come into contact remains the cold incoming water. The fire is positively cut off when the pressure reaches a pre-determined point, usually set at 750 psi (5.2 MPa), cold water pressure; a safety valve set at 1,200 lb (544 kg) provides added protection. The fire is automatically cut off by temperature as well as pressure, so in case the boiler were completely dry it would be impossible to damage
2145-405: The heat source to the water. The water is confined in a restricted space heated by the fire. The steam produced has lower density than the water and therefore will accumulate at the highest level in the vessel; its temperature will remain at boiling point and will only increase as pressure increases. Steam in this state (in equilibrium with the liquid water which is being evaporated within the boiler)
2200-402: The hot gases exiting the firebox; the saturated steam flows backwards from the wet header towards the firebox, then forwards again to the dry header. Superheating only began to be generally adopted for locomotives around the year 1900 due to problems of overheating of and lubrication of the moving parts in the cylinders and steam chests . Many firetube boilers heat water until it boils, and then
2255-403: The indoor air humidity needs to be lowered, or air ventilation in the building needs to be improved. This can be done in a number of ways, for example opening windows, turning on extractor fans, using dehumidifiers, drying clothes outside and covering pots and pans whilst cooking. Air conditioning or ventilation systems can be installed that help remove moisture from the air, and move air throughout
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2310-552: The industry for example in heating systems or for cement production, steam boilers are used in agriculture as well for soil steaming . The preeminent code for testing fired steam generators in the USA is the American Society of Mechanical Engineers (ASME) performance test code, PTC 4. A related component is the regenerative air heater. A major revision to the performance test code for air heaters will be published in 2013. Copies of
2365-458: The locomotive moved against the cutting heads, its wheels were cut back to a desirable profile. In a locomotive maintenance facility of the steam engine era (until, generally, the mid-1950s in the US) the place where this was done was sometimes known as the "Lidgerwood Track". Maintenance of a railroad embankment may require material (soil, rock, etc.) to be moved from where it is deposited by erosion near
2420-429: The molecular density in the gas phase reaches its maximal threshold. Vapor cooling and compressing equipment that collects condensed liquids is called a "condenser" . Psychrometry measures the rates of condensation through evaporation into the air moisture at various atmospheric pressures and temperatures. Water is the product of its vapor condensation—condensation is the process of such phase conversion. Condensation
2475-498: The scheme to his son Robert and this was the boiler used on Stephenson's Rocket , outright winner of the trial. The design formed the basis for all subsequent Stephensonian-built locomotives, being immediately taken up by other constructors; this pattern of fire-tube boiler has been built ever since. The 1712 boiler was assembled from riveted copper plates with a domed top made of lead in the first examples. Later boilers were made of small wrought iron plates riveted together. The problem
2530-581: The steam is heated to a temperature above the saturation temperature, and no liquid water can exist under this condition. Most reciprocating steam engines of the 19th century used saturated steam, however modern steam power plants universally use superheated steam which allows higher steam cycle efficiency. L.D. Porta gives the following equation determining the efficiency of a steam locomotive , applicable to steam engines of all kinds: power (kW) = steam Production (kg h )/Specific steam consumption (kg/kW h). A greater quantity of steam can be generated from
2585-402: The steam is used at saturation temperature in other words the temperature of the boiling point of water at a given pressure (saturated steam); this still contains a large proportion of water in suspension. Saturated steam can and has been directly used by an engine, but as the suspended water cannot expand and do work and work implies temperature drop, much of the working fluid is wasted along with
2640-412: The steam pressure alone drove the piston and was then exhausted to atmosphere. The advantage of strong steam as he saw it was that more work could be done by smaller volumes of steam; this enabled all the components to be reduced in size and engines could be adapted to transport and small installations. To this end he developed a long cylindrical wrought iron horizontal boiler into which was incorporated
2695-419: The superheater steam piping and the steam within as well. While the temperature of the steam in the superheater is raised, the pressure of the steam is not: the turbine or moving pistons offer a "continuously expanding space" and the pressure remains the same as that of the boiler. The process of superheating steam is most importantly designed to remove all droplets entrained in the steam to prevent damage to
2750-485: The track to a place where the embankment has been eroded away, or a railroad may need to simply widen the cut and fill sections. One method to do this was to mount a winch on one flat car (colloquially known as the Lidgerwood Car and in some cases labeled as such) with a line connected to a plow that was configured to slide along the decks of many flat cars. Soil material was shoveled (manually or by power equipment) onto
2805-461: The turbine blading and/or associated piping. Superheating the steam expands the volume of steam, which allows a given quantity (by weight) of steam to generate more power. When the totality of the droplets is eliminated, the steam is said to be in a superheated state. In a Stephensonian firetube locomotive boiler, this entails routing the saturated steam through small diameter pipes suspended inside large diameter firetubes putting them in contact with
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#17328583843872860-419: The way). As the successor company is still in business it is probable that they continue to be used in the railroad industry for moving cars through current (2013) times. Railroad wheels need to have a specific profile. As the profile wears into degraded shapes their performance becomes irregular and eventually unsafe. Most wheels are re-profiled using some variation of a wheel lathe or milling machine; but it
2915-454: Was producing big enough plates, so that even pressures of around 50 psi (344.7 kPa ) were not absolutely safe, nor was the cast iron hemispherical boiler initially used by Richard Trevithick. This construction with small plates persisted until the 1820s, when larger plates became feasible and could be rolled into a cylindrical form with just one butt-jointed seam reinforced by a gusset ; Timothy Hackworth's Sans Pareil 11 of 1849 had
2970-479: Was the American engineer, Oliver Evans , who rightly recognised that the cylindrical form was the best from the point of view of mechanical resistance and towards the end of the 18th century began to incorporate it into his projects. Probably inspired by the writings on Leupold's "high-pressure" engine scheme that appeared in encyclopaedic works from 1725, Evans favoured "strong steam" i.e. non condensing engines in which
3025-488: Was the Cornishman, Richard Trevithick . His boilers worked at 40–50 psi (276–345 kPa) and were at first of hemispherical then cylindrical form. From 1804 onwards Trevithick produced a small two-pass or return flue boiler for semi-portable and locomotive engines. The Cornish boiler developed around 1812 by Richard Trevithick was both stronger and more efficient than the simple boilers which preceded it. It consisted of
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