Advanced boiling water reactor
The advanced boiling water reactor is a Generation III boiling water reactor. The ABWR is offered by GE Hitachi Nuclear Energy and Toshiba; the ABWR generates electrical power by using steam to power a turbine connected to a generator. Kashiwazaki-Kariwa unit 6 is considered the first Generation III reactor in the world. Boiling water reactors are the second most common form of light water reactor with a direct cycle design that uses fewer large steam supply components than the pressurized water reactor, which employs an indirect cycle; the ABWR is the present state of the art in boiling water reactors, is the first Generation III reactor design to be built, with several reactors complete and operating. The first reactors were built on time and under budget in Japan, with others under construction there and in Taiwan. ABWRs were on order including two reactors at the South Texas Project site; the projects in both Taiwan and US are both reported over-budgeted. The standard ABWR plant design has a net electrical output of about 1.35 GW, generated from about 3926 MW of thermal power.
The ABWR represents an evolutionary route for the BWR family, with numerous changes and improvements to previous BWR designs. Major areas of improvement include: The addition of reactor internal pumps mounted on the bottom of the reactor pressure vessel - 10 in total - which achieve improved performance while eliminating large recirculation pumps in containment and associated large-diameter and complex piping interfaces with the RPV. Only the RIP motor is located outside of the RPV in the ABWR. According to the Tier 1 Design Control Document, each RIP has a nominal capacity of 6912 m3/h; the control rod adjustment capabilities have been supplemented with the addition of an electro-hydraulic Fine Motion Control Rod Drive, allowing for fine position adjustment using an electrical motor, while not losing the reliability or redundancy of traditional hydraulic systems which are designed to accomplish rapid shutdown in 2.80 s from receipt of an initiating signal, or ARI in a greater but still insignificant time period.
The FMCRD improves defense-in-depth in the event of primary hydraulic and ARI contingencies. A digital Reactor Protection System ensures a high level of reliability and simplification for safety condition detection and response; this system initiates rapid hydraulic insertion of control rods for shutdown. Two-out-of-four per parameter rapid shutdown logic ensures that nuisance rapid shutdowns are not triggered by single instrument failures. RPS can trigger ARI, FMCRD rod run-in to shut down the nuclear chain reaction; the standby liquid control system actuation is provided as diverse logic in the unlikely event of an Anticipated Transient Without Scram. Digital reactor controls allow the control room to and control plant operations and processes. Separate redundant safety and non-safety related digital multiplexing buses allow for reliability and diversity of instrumentation and control. In particular, the reactor is automated for startup and for standard shutdown using automatic systems only.
Of course, human operators remain essential to reactor control and supervision, but much of the busy-work of bringing the reactor to power and descending from power can be automated at operator discretion. The Emergency Core Cooling System has been improved in many areas, providing a high level of defense-in-depth against accidents and incidents; the overall system has been divided up into 3 divisions. Previous BWRs had 2 divisions, uncovery was predicted to occur for a short time in the event of a severe accident, prior to ECCS response. Eighteen SORVs, eight of which are part of the ADS, ensure that RPV overpressure events are mitigated, that if necessary, that the reactor can be depressurized to a level where low pressure core flooder can be used. Further, LPCF can inject against much higher RPV pressures, providing an increased level of safety in the event of intermediate-sized breaks, which could be small enough to result in slow natural depressurization but could be large enough to result in high pressure corespray/coolant injection systems' capacities for response being overwhelmed by the size of the break.
Though the Class 1E power bus is still powered by 3 highly-reliable emergency diesel generators that are safety related, an additional Plant Investment Protection power bus using a combustion gas turbine is located on-site to generate electricity to provide defense-in-depth against station blackout contingencies as well as to power important but non-safety critical systems in the event of a loss of offsite power. Though one division of the ECCS does not have high pressu
Beloyarsk Nuclear Power Station
The Beloyarsk Nuclear Power Station was the third of the Soviet Union's nuclear plants. It is situated by Zarechny in Russia. Zarechny township was created to service the station, named after the Beloyarsky District; the closest city is Yekaterinburg. Two earlier reactors were constructed at Beloyarsk: an AMB-200 reactor. Both were supercritical water reactors; the first unit had an indirect steam cycle. Although they were comparable in power to the Shippingport Atomic Power Station, the Soviet planners regarded the Beloyarsk reactors as prototypes, their main novelty was the use of superheated steam ran through a standard turbine thus resulting in a better efficiency compared to the earlier Obninsk Nuclear Power Plant pilot plant. The first Beloyarsk unit produced about 285 MW heat of which about 100 MW were converted to electricity; the second unit, which used two turbines, had a similar conversion efficiency of about 36%. Two reactors are now in operation: a BN-600 fast breeder reactor, generating 600 MWe gross and a BN-800 fast breeder reactor, generating 885 MWe gross.
The BN-800 is the largest fast neutron power reactor in service in the world. Three turbines are connected to the BN-600 reactor; the BN-600 reactor core has a diameter of 2.05 metres. It has 369 fuel assemblies, each consisting of 127 fuel rods with an enrichment of 17–26% 235U. In comparison, typical enrichment in other Russian reactors is in the range of 3–4% 235U. BN-600 reactors use liquid sodium as a coolant; as with most Russian nuclear power plants, the station lacks a containment building. Construction started on the larger BN-800 fast breeder reactor in 1987. Protests halted progress in 1988, but work resumed in 1992 following an order by President Boris Yeltsin. Financial difficulties resulted in slow progress. Construction costs have been estimated at 1 trillion rubles and the new reactor was expected to be finished in 2012–2015; the BN-600 was planned to be decommissioned in 2010 but its lifetime was expected to be extended to cover the gap. On 27 June 2014, controlled nuclear fission started in the BN-800 fast breeder reactor.
The newest reactor helps to close the nuclear fuel cycle and to achieve a fuel cycle without or with less nuclear waste. Russia was, at the date, the only country; however issues detected during low power operation required further fuel development work. On 31 July 2015, the unit again achieved minimum controlled power again, at 0.13% of rated power. Commercial operations are expected to start before the end of 2016, now with a power rating of 789 MWe. In December 2015, Unit 4 was connected to the national grid; the two gravest incidents at Beloyarsk Nuclear Power Plant struck the two reactors which are now shut down. In 1977 half of the fuel rods melted down in the ABM-200 reactor. Operators were exposed to severe radiation doses, the repair work took more than a year. In December 1978 the same reactor caught fire when parts of the roof fell on one of the turbines' oil tanks. Cables were destroyed by the fire, the reactor went out of control. Eight people who assisted in securing cooling of the reactor core were exposed to increased radiation doses.
In recent years there have been problems with leakage of liquid metal from the BN-600 cooling system. In December 1992 there was a leakage of radioactive contaminated water at the reactor. In October 1993 increased concentrations of radioactivity in the power plant fan system were found. A leakage the following month led to a shutdown. In January and May 1994 there was a fire at the power plant. In July 1995 another leakage of liquid metal from the cooling elements caused a two-week shutdown of the reactor. There is an increasing concern about radioactive contamination around the power plant. Several hotspots were discovered in the region, as the radiation monitoring effort was extended in recent years. Nuclear power in Russia Dollezhal, N. A.. "The uranium-graphite reactor and superheated steam power stations". Journal of Nuclear Energy. 7: 109. Doi:10.1016/0891-391990242-0. For the design of the first two reactors. Beloyarsk NPP, INSP programme Beloyarskaya NPP, official site Beloyarskaya NPP, manufacturer information
Critical point (thermodynamics)
In thermodynamics, a critical point is the end point of a phase equilibrium curve. The most prominent example is the liquid-vapor critical point, the end point of the pressure-temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas cannot be liquefied by pressure alone. At the critical point, defined by a critical temperature Tc and a critical pressure pc, phase boundaries vanish. Other examples include the liquid–liquid critical points in mixtures. For simplicity and clarity, the generic notion of critical point is best introduced by discussing a specific example, the liquid-vapor critical point; this was the first critical point to be discovered, it is still the best known and most studied one. The figure to the right shows the schematic PT diagram of a pure substance; the known phases solid and vapor are separated by phase boundaries, i.e. pressure-temperature combinations where two phases can coexist. At the triple point, all three phases can coexist.
However, the liquid-vapor boundary terminates in an endpoint at some critical temperature Tc and critical pressure pc. This is the critical point. In water, the critical point occurs at 22.064 MPa. In the vicinity of the critical point, the physical properties of the liquid and the vapor change with both phases becoming more similar. For instance, liquid water under normal conditions is nearly incompressible, has a low thermal expansion coefficient, has a high dielectric constant, is an excellent solvent for electrolytes. Near the critical point, all these properties change into the exact opposite: water becomes compressible, expandable, a poor dielectric, a bad solvent for electrolytes, prefers to mix with nonpolar gases and organic molecules. At the critical point, only one phase exists; the heat of vaporization is zero. There is a stationary inflection point in the constant-temperature line on a PV diagram; this means that at the critical point: T = 0 T = 0 Above the critical point there exists a state of matter, continuously connected with both the liquid and the gaseous state.
It is called supercritical fluid. The common textbook knowledge that all distinction between liquid and vapor disappears beyond the critical point has been challenged by Fisher and Widom who identified a p,T-line that separates states with different asymptotic statistical properties; the existence of a critical point was first discovered by Charles Cagniard de la Tour in 1822 and named by Dmitri Mendeleev in 1860 and Thomas Andrews in 1869. Cagniard showed that CO2 could be liquefied at 31 °C at a pressure of 73 atm, but not at a higher temperature under pressures as high as 3,000 atm. Solving the above condition T = 0 for the van der Waals equation, one can compute the critical point as T c = 8 a 27 R b, V c = 3 n b, p c = a 27 b 2. However, the van der Waals equation, based on a mean field theory, does not hold near the critical point. In particular, it predicts wrong scaling laws. To analyse properties of fluids near the critical point, reduced state variables are sometimes defined relative to the critical properties T r = T T c, p r = p p c, V r = V R T c / p c.
The principle of corresponding states indicates that substances at equal reduced pressures and temperatures have equal reduced volumes. This relationship is true for many substances, but becomes inaccurate for large values of pr. For some gases, there is an additional correction factor, called Newton's correction, added to the critical temperature and critical pressure calculated in this manner; these vary with the pressure range of interest. The liquid–liquid critical point of a solution, which occurs at the critical solution temperature, occurs at the limit of the two-phase region of the phase diagram. In other words, it is the point at which an infinitesimal change in some thermodynamic variable will lead to separation of the mixture into two distinct liquid phases, as shown in the polymer–solvent phase diagram to the right. Two types of liquid–liquid critical points are the upper critical solution temperature, t
Generation III reactor
A Generation III reactor is a development of Generation II nuclear reactor designs incorporating evolutionary improvements in design developed during the lifetime of the Generation II reactor designs. These include improved fuel technology, superior thermal efficiency enhanced safety systems, standardized designs for reduced maintenance and capital costs; the first Generation III reactor to begin operation was Kashiwazaki 6 in 1996. Due to the prolonged period of stagnation in the construction of new reactors and the continued popularity of Generation II/II+ designs in new construction few third generation reactors have been built. Generation IV designs are still in development as of 2017, are not expected to start entering commercial operation until 2020–2030. Though the distinction is arbitrary, the improvements in reactor technology in third generation reactors are intended to result in a longer operational life compared with used Generation II reactors; the core damage frequencies for these reactors are designed to be lower than for Generation II reactors – 60 core damage events for the EPR and 3 core damage events for the ESBWR per 100 million reactor-years are lower than the 1,000 core damage events per 100 million reactor-years for BWR/4 Generation II reactors.
The third generation EPR reactor was designed to use uranium more efficiently than older Generation II reactors, using 17% less uranium per unit of electricity generated than these older reactor technologies. An independent analysis conducted by environmental scientist Barry Brook on the greater efficiency and therefore lower material needs of Gen III reactors, corroborates this finding. Proponents of nuclear power and some who have been critical have acknowledged that third generation reactors as a whole are safer than older reactors. Edwin Lyman, a senior staff scientist at the Union of Concerned Scientists, has challenged specific cost-saving design choices made for two Generation III reactors, both the AP1000 and ESBWR. Lyman, John Ma, Arnold Gundersen are concerned about what they perceive as weaknesses in the steel containment vessel and the concrete shield building around the AP1000 in that its containment vessel does not have sufficient safety margins in the event of a direct airplane strike.
Other engineers do not agree with these concerns, claim the containment building is more than sufficient in safety margins and factors of safety. The Union of Concerned Scientists in 2008 referred to the EPR as the only new reactor design under consideration in the United States that "...appears to have the potential to be safer and more secure against attack than today's reactors."There have been issues in fabricating the precision parts necessary to maintain safe operation of these reactors, with cost overruns, broken parts, fine steel tolerances causing issues with new reactors under construction in France at the Flamanville Nuclear Power Plant. The first Generation III reactors were built in Japan, in the form of Advanced Boiling Water Reactors. In 2016 a Generation III+ VVER-1200/392M reactor became operational at Novovoronezh Nuclear Power Plant II in Russia, the first operational Generation III+ reactor. Several other Generation III+ reactors are under late-stage construction in Europe and the United States.
The next Generation III+ reactor to come online is a Westinghouse AP1000 reactor, the Sanmen Nuclear Power Station in China, scheduled to become operational in 2015. It has been completed and achieved criticality on June 21, 2018, entered into commercial operation on September 21, 2018. In the USA, reactor designs are certified by the Nuclear Regulatory Commission; as of October 2014 the commission has approved five designs, is considering another five designs as well. Generation III+ designs offer significant improvements in safety and economics over Generation III advanced reactor designs. Generation II reactor Generation IV reactor List of reactor types Nuclear Reactors Knowledge Base, IAEA Advanced Nuclear Power Reactors, World Nuclear Association, May 2008
A supercritical fluid is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist. It can effuse through solids like a gas, dissolve materials like a liquid. In addition, close to the critical point, small changes in pressure or temperature result in large changes in density, allowing many properties of a supercritical fluid to be "fine-tuned". Supercritical fluids occur in the atmospheres of the gas giants Jupiter and Saturn, in those of the ice giants Uranus and Neptune. In a range of industrial and laboratory processes, they are used as a substitute for organic solvents. Carbon dioxide and water are the most used supercritical fluids, being used for decaffeination and power generation, respectively. In general terms, supercritical fluids have properties between those of a liquid. In Table 1, the critical properties are shown for some substances that are used as supercritical fluids. Table 2 shows density and viscosity for typical liquids and supercritical fluids.
In addition, there is no surface tension in a supercritical fluid, as there is no liquid/gas phase boundary. By changing the pressure and temperature of the fluid, the properties can be "tuned" to be more liquid-like or more gas-like. One of the most important properties is the solubility of material in the fluid. Solubility in a supercritical fluid tends to increase with density of the fluid. Since density increases with pressure, solubility tends to increase with pressure; the relationship with temperature is a little more complicated. At constant density, solubility will increase with temperature. However, close to the critical point, the density can drop with a slight increase in temperature. Therefore, close to the critical temperature, solubility drops with increasing temperature rises again. All supercritical fluids are miscible with each other so for a mixture a single phase can be guaranteed if the critical point of the mixture is exceeded; the critical point of a binary mixture can be estimated as the arithmetic mean of the critical temperatures and pressures of the two components, Tc = × TcA + × TcB.
For greater accuracy, the critical point can be calculated using equations of state, such as the Peng Robinson, or group contribution methods. Other properties, such as density, can be calculated using equations of state. Figures 1 and 2 show two-dimensional projections of a phase diagram. In the pressure-temperature phase diagram the boiling separates the gas and liquid region and ends in the critical point, where the liquid and gas phases disappear to become a single supercritical phase; the appearance of a single phase can be observed in the density-pressure phase diagram for carbon dioxide. At well below the critical temperature, e.g. 280 K, as the pressure increases, the gas compresses and condenses into a much denser liquid, resulting in the discontinuity in the line. The system consists of 2 phases in a dense liquid and a low density gas; as the critical temperature is approached, the density of the gas at equilibrium becomes higher, that of the liquid lower. At the critical point, there is no difference in density, the 2 phases become one fluid phase.
Thus, above the critical temperature a gas cannot be liquefied by pressure. At above the critical temperature, in the vicinity of the critical pressure, the line is vertical. A small increase in pressure causes a large increase in the density of the supercritical phase. Many other physical properties show large gradients with pressure near the critical point, e.g. viscosity, the relative permittivity and the solvent strength, which are all related to the density. At higher temperatures, the fluid starts to behave like a gas, as can be seen in Figure 2. For carbon dioxide at 400 K, the density increases linearly with pressure. Many pressurized gases are supercritical fluids. For example, nitrogen has a critical point of 3.4 MPa. Therefore, nitrogen in a gas cylinder above this pressure is a supercritical fluid; these are more known as permanent gases. At room temperature, they are well above their critical temperature, therefore behave as a gas, similar to CO2 at 400 K above. However, they can not be liquified by pressure.
In recent years, a significant effort has been devoted to investigation of various properties of supercritical fluids. This has been an exciting field with a long history since 1822 when Baron Charles Cagniard de la Tour discovered supercritical fluids while conducting experiments involving the discontinuities of the sound in a sealed cannon barrel filled with various fluids at high temperature. More supercritical fluids have found application in a variety of fields, ranging from the extraction of floral fragrance from flowers to applications in food science such as creating decaffeinated coffee, functional food ingredients, cosmetics, powders, bio- and functional materials, nano-systems, natural products, biotechnology and bio-fuels, microelectronics and environment. Much of the excitement and interest of the past decade is due to the enormous progress made in increasing the power of relevant experimental tools; the development of new experimental methods and improvement of existing ones continues to play an important role in this field, with recent research focusing on dynamic properties of fluids.
The Fisher-Widom line, the Widom line, or the Frenk
Control rods are used in nuclear reactors to control the fission rate of uranium and plutonium. They are composed of chemical elements such as boron, silver and cadmium that are capable of absorbing many neutrons without themselves fissioning; because these elements have different capture cross sections for neutrons of varying energies, the composition of the control rods must be designed for the reactor's neutron spectrum. Boiling water reactors, pressurized water reactors and heavy water reactors operate with thermal neutrons, while breeder reactors operate with fast neutrons. Control rods are used in control rod assemblies and inserted into guide tubes within a fuel element. A control rod is removed from or inserted into the central core of a nuclear reactor in order to increase or decrease the neutron flux, which describes the number of neutrons that split further uranium atoms; this in turn affects the thermal power, the amount of steam produced and hence the electricity generated. Control rods stand vertically within the core.
In PWRs they are inserted from above, with the control rod drive mechanisms mounted on the reactor pressure vessel head. In BWRs, due to the necessity of a steam dryer above the core, this design requires insertion of the control rods from beneath; the control rods are removed from the core to allow a chain reaction to occur. The number of control rods inserted and the distance to which they are inserted can be varied to control activity. Typical shutdown time for modern reactors such as the European Pressurized Reactor or Advanced CANDU reactor is 2 seconds for 90% reduction, limited by decay heat. Chemical elements with a sufficiently high neutron capture cross-section include silver and cadmium. Other candidate elements include boron, hafnium, europium, terbium, holmium, thulium and lutetium. Alloys or compounds may be used, such as high-boron steel, silver-indium-cadmium alloy, boron carbide, zirconium diboride, titanium diboride, hafnium diboride, gadolinium nitrate, gadolinium titanate, dysprosium titanate and boron carbide - europium hexaboride composite.
The material choice is influenced by the neutron energy in the reactor, their resistance to neutron-induced swelling and the required mechanical and lifespan properties. The rods may have the form of tubes filled with neutron-absorbing pellets or powder, they can be made out of stainless steel or other neutron window materials such as zirconium, silicon carbide or cubic 11B15N. The burn up of the absorbing isotopes is another limiting lifespan factor, they may be reduced by capturing long isotope rows of the same element or by not using neutron absorbers for trimming. For example, in pebble bed reactors or in possible new type 7lithium-moderated and -cooled reactors that use fuel and absorber pebbles; some rare earth elements are less rare than silver. For example and yttrium, 400 times more common, with middle capturing values, can be found and used together without separation inside minerals like xenotime PO4, or keiviite 2Si2O7, lowering the cost. Xenon is a strong neutron absorber as a gas and can be used for controlling and stopping of helium-cooled reactors, but does not function in cases of pressure loss, or as a burning protection gas together with argon around the vessel part in case of core catching reactors or if filled with sodium or lithium.
Fission-produced xenon can be used after waiting for caesium to precipitate, when no radioactivity is left. Cobalt 59 is used as an absorber for winning of cobalt 60 for x-ray production. Control rods can be constructed as thick turnable rods with a tungsten reflector and absorber side turned to stop by a spring in less than 1 second. Silver-indium-cadmium alloys 80% Ag, 15% In and 5% Cd, are a common control rod material for pressurized water reactors; the somewhat different energy absorption regions of the materials make the alloy an excellent neutron absorber. It has good mechanical strength and can be fabricated, it must be encased in stainless steel to prevent corrosion in hot water. Although indium is less rare than silver, it is more expensive. Boron is another common neutron absorber. Due to the different cross sections of 10B and 11B, materials containing boron enriched in 10B by isotopic separation are used; the wide absorption spectrum of boron makes it suitable as a neutron shield. The mechanical properties of boron in its elementary form are unsuitable, therefore alloys or compounds have to be used instead.
Common choices are boron carbide. The latter is used as a control rod material in both BWRs. 10B/11B separation is done commercially with gas centrifuges over BF3, but can be done over BH3 from borane production or directly with an energy optimized melting centrifuge, using the heat of freshly separated boron for preheating. Hafnium has excellent properties for reactors cooling, it has good mechanical strength, can be fabricated, is resistant to corrosion in hot water. Hafnium can be alloyed with other elements, e.g. with tin and oxygen to increase tensile and creep strength, with iron and niobium for corrosion resistance, with molybdenum for wear resistance and machineability. Such alloys are designated as Hafaloy, Hafaloy-M, Hafaloy-N, Hafaloy-NM; the high cost and low availability of hafnium limit its use in civilian reactors, although it
A boiler is a closed vessel in which fluid is heated. The fluid does not boil; the heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation and sanitation. In a fossil fuel power plant using a steam cycle for power generation, the primary heat source will be combustion of coal, oil, or natural gas. In some cases byproduct fuel such as the carbon-monoxide rich offgasses of a coke battery can be burned to heat a boiler. In a nuclear power plant, boilers called steam generators are heated by the heat produced by nuclear fission. Where a large volume of hot gas is available from some process, a heat recovery steam generator or recovery boiler can use the heat to produce steam, with little or no extra fuel consumed. In all cases the combustion product waste gases are separate from the working fluid of the steam cycle, making these systems examples of External combustion engines; the pressure vessel of a boiler is made of steel, or of wrought iron.
Stainless steel of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion cracking. However, ferritic stainless steel is used in superheater sections that will not be exposed to boiling water, electrically-heated stainless steel shell boilers are allowed under the European "Pressure Equipment Directive" for production of steam for sterilizers and disinfectors. In live steam models, copper or brass is used because it is more fabricated in smaller size boilers. Copper was used for fireboxes, because of its better formability and higher thermal conductivity. For much of the Victorian "age of steam", the only material used for boilermaking was the highest grade of wrought iron, with assembly by riveting; this iron was obtained from specialist ironworks, such as those in the Cleator Moor area, noted for the high quality of their rolled plate, suitable for use in critical applications such as high-pressure boilers. In the 20th century, design practice moved towards the use of steel, with welded construction, stronger and cheaper, can be fabricated more and with less labour.
Wrought iron boilers corrode far more than their modern-day steel counterparts, are less susceptible to localized pitting and stress-corrosion. That makes the longevity of older wrought-iron boilers far superior to that of welded steel boilers. Cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are termed "boilers" in some countries, their purpose is to produce hot water, not steam, so they run at low pressure and try to avoid boiling; the brittleness of cast iron makes it impractical for high-pressure steam boilers. The source of heat for a boiler is combustion of any of several fuels, such as wood, oil, or natural gas. Electric steam boilers use resistance- or immersion-type heating elements. Nuclear fission is used as a heat source for generating steam, either directly or, in most cases, in specialised heat exchangers called "steam generators". Heat recovery steam generators use. There are two methods to measure the boiler efficiency: Direct method Indirect methodDirect method: Direct method of boiler efficiency test is more usable or more common.
Boiler efficiency = power out / power in = / * 100%Q = rate of steam flow in kg/h Hg = enthalpy of saturated steam in kcal/kg Hf = enthalpy of feed water in kcal/kg q = rate of fuel use in kg/h GCV = gross calorific value in kcal/kg Indirect method: To measure the boiler efficiency in indirect method, we need a following parameter like: Ultimate analysis of fuel 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 fuel in kcal/kg Ash percentage in combustible fuel GCV of ash in kcal/kg Boilers can be classified into the following configurations: Pot boiler or Haycock boiler/Haystack boiler: A primitive "kettle" where a fire heats a filled water container from below. 18th century Haycock boilers produced and stored large volumes of low-pressure steam hardly above that of the atmosphere. These could burn wood or most coal. Efficiency was low. Flued boiler with one or two large flues—an early type or forerunner of fire-tube boiler.
Fire-tube boiler: Here, water fills a boiler barrel with a small volume left above to accommodate the steam. This is the type of boiler used in nearly all steam locomotives; the heat source is inside a furnace or firebox that has to be kept permanently 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 surface which can be further increased by making the gases reverse direction through a second parallel tube or a bundle of multiple tubes. In case of a locomotive-type boiler, a boiler