What is the process of combustion?
Combustion
Combustion processes which happen in very small volumes are considered micro-combustion. The high surface-to-volume ratio increases specific heat loss. Quenching distance plays a vital role in stabilizing the flame in such combustion chambers.
Carbon-burning process
The carbon-burning process or carbon fusion is a set of nuclear fusion reactions that take place in the cores of massive stars (at least 8 formula_1 at birth) that combines carbon into other elements. It requires high temperatures (> 5×10 K or 50 keV) and densities (> 3×10 kg/m).
Incineration
Incineration is a waste treatment process that involves the combustion of organic substances contained in waste materials. Incineration and other high-temperature waste treatment systems are described as "thermal treatment". Incineration of waste materials converts the waste into ash, flue gas and heat. The ash is mostly formed by the inorganic constituents of the waste and may take the form of solid lumps or particulates carried by the flue gas. The flue gases must be cleaned of gaseous and particulate pollutants before they are dispersed into the atmosphere. In some cases, the heat generated by incineration can be used to generate electric power.
Heat of combustion
By convention, the heat of combustion is defined to be the heat released for the complete combustion of a compound in its standard state to form stable products in their standard states: hydrogen is converted to water (in its liquid state), carbon is converted to carbon dioxide gas, and nitrogen is converted to nitrogen gas. That is, the heat of combustion, Δ"H°", is the heat of reaction of the following process:
Combustion (software)
The last version of Combustion was Combustion 2008. The end of its development was never officially announced, but the company was known to be concurrently developing a new compositing platform, Autodesk Toxik
Candoluminescence
When the fuel in a flame combusts, the energy released by the combustion process is deposited in combustion products, usually molecular fragments called free radicals. The combustion products are excited to a very high temperature called the adiabatic flame temperature (that is, the temperature before any heat has been transferred away from the combustion products). This temperature is usually much higher than the temperature of the air in the flame or which an object inserted into the flame can reach. When the combustion products lose this energy by radiative emission, the radiation can thus be more intense than that of a lower-temperature blackbody inserted into the flame. The exact emission process involved varies with the material, the type of fuels and oxidizers, and the type of flame, though in many cases it is well established that the free radicals undergo radiative recombination. This energetic light emitted directly from the combustion products may be observed directly (as with a blue gas flame), depending on the wavelength, or it may then cause fluorescence in the candoluminescent material. Some free-radical recombinations emit ultraviolet light, which is only observable through fluorescence.
Combustion engine
A combustion engine is an engine which generates mechanical power by combustion of a fuel. Combustion engines are of two general types:
Spontaneous combustion
The process may begin with microbiological activity (bacteria or mold), but at some point, the process has to become chemical. Microbiological activity will also limit the amount of oxygen available in the hay. Moisture appears to be quite important, no matter what process. At 100 °C, wet hay absorbed twice the amount of oxygen of dry hay. There has been conjecture that the complex carbohydrates present in hay break down to simpler sugars, which are more readily oxidized.
Combustion
Combustion of an organic fuel in air is always exothermic because the double bond in O is much weaker than other double bonds or pairs of single bonds, and therefore the formation of the stronger bonds in the combustion products and results in the release of energy. The bond energies in the fuel play only a minor role, since they are similar to those in the combustion products; e.g., the sum of the bond energies of CH is nearly the same as that of . The heat of combustion is approximately -418 kJ per mole of O used up in the combustion reaction, and can be estimated from the elemental composition of the fuel.
Combustion
The act of combustion consists of three relatively distinct but overlapping phases:
Paraho process
The Paraho process can be operated in two different heating modes, which are direct and indirect. The Paraho Direct process evolved from gas combustion retort technology and is classified as an internal combustion method. Accordingly, the Paraho Direct retort is a vertical shaft retort similar to the Kiviter and Fushun retorts, used correspondingly in Estonia and China. However, compared to the earlier gas combustion retorts the Paraho retort's raw oil shale feeding mechanism, gas distributor, and discharge grate have different designs. In the Paraho Direct process, the crushed and screened raw oil shale is fed into the top of the retort through a rotating distributor. The oil shale descends the retort as a moving bed. The oil shale is heated by the rising combustion gases from the lower part of the retort and the kerogen in the shale decomposes at about to oil vapour, shale oil gas and spent shale. Heat for pyrolysis comes from the combustion of char in the spent shale. The combustion takes place where air is injected at two levels in the middle of the retort below the pyrolysis section raising the temperature of the shale and the gas to to . Collecting tubes at the top of the retort carry shale oil mist, evolved gases and combustion gases into the product separation unit, where oil, water and dust are separated from the gases. For combined removal of liquid droplets and particulates, a wet electrostatic precipitator is used. Cleaned gases from the precipitator are compressed in a compressor. Part of the gas from the compressor is recycled to the bottom of the retort to cool the combusted shale (shale ash) and carry the recovered heat back up the retort. Cooled shale ash exits the retort through the discharge grate in the bottom of the retort. After processing, shale ash is disposed of. The liquid oil is separated from produced water and may be further refined into high quality products. The mixture of evolved gases and combustions gases is available for use as a low quality fuel gas for drying or power generation.
Theory and Construction of a Rational Heat Motor
The Diesel process is a hypothetical constant-pressure model, with four distinct processes, a so-called "cycle", meaning that these four distinct processes can be repeated over and over again. These distinct processes are the same processes that can be found in a four-stroke engine: intake, compression, combustion, exhaust. All four strokes combined form the "cycle", which is supposed to result in useful work. The Diesel process uses a special compression stroke based on the idea, that a gas can be compressed in a combined "isothermal-adiabatic" way. Isothermal means, that the temperature during compression does not change, thus requiring heat dissipation; adiabatic means, that the gas changes its volume, but "without heat dissipation". This means that there is no waste heat.
Lurgi–Ruhrgas process
The spent oil shale, still including residual carbon (char), is burnt at a lift pipe combustor to heat the process. If necessary, additional fuel oil is used for combustion. During the combustion process, heated solid particles in the pipe are moved to the surge bin by pre-heated air that is introduced from the bottom of the pipe. At the surge bin, solids and gases are separated, and solid particles are transferred to the mixer unit to conduct the pyrolysis of the raw oil shale.
Environmental impact of biodiesel
Carbon dioxide is one of the major greenhouse gases. Although the burning of biodiesel produces carbon dioxide emissions similar to those from ordinary fossil fuels, the plant feedstock used in the production absorbs carbon dioxide from the atmosphere when it grows. Plants absorb carbon dioxide through a process known as photosynthesis which allows it to store energy from sunlight in the form of sugars and starches. After the biomass is converted into biodiesel and burned as fuel the energy and carbon is released again. Some of that energy can be used to power an engine while the carbon dioxide is released back into the atmosphere.
Condensing boiler
One of the hot gases produced in the combustion process is water vapour (steam), which arises from burning the hydrogen content of the fuel. A condensing boiler extracts additional heat from the waste gases by condensing this water vapour to liquid water, thus recovering its latent heat of vaporization. A typical increase of efficiency can be as much as 10-12%. While the effectiveness of the condensing process varies depending on the temperature of the water returning to the boiler, it is always at least as efficient as a non-condensing boiler.
Oxygen
In the late 17th century, Robert Boyle proved that air is necessary for combustion. English chemist John Mayow (1641–1679) refined this work by showing that fire requires only a part of air that he called "spiritus nitroaereus". In one experiment, he found that placing either a mouse or a lit candle in a closed container over water caused the water to rise and replace one-fourteenth of the air's volume before extinguishing the subjects. From this he surmised that nitroaereus is consumed in both respiration and combustion.
Fire (disambiguation)
Fire is the rapid oxidation of a material in the chemical process of combustion.
Combustion
Fires occur naturally, ignited by lightning strikes or by volcanic products. Combustion (fire) was the first controlled chemical reaction discovered by humans, in the form of campfires and bonfires, and continues to be the main method to produce energy for humanity. Usually, the fuel is carbon, hydrocarbons or more complicated mixtures such as wood that contains partially oxidized hydrocarbons. The thermal energy produced from combustion of either fossil fuels such as coal or oil, or from renewable fuels such as firewood, is harvested for diverse uses such as cooking, production of electricity or industrial or domestic heating. Combustion is also currently the only reaction used to power rockets. Combustion is also used to destroy (incinerate) waste, both nonhazardous and hazardous.
Fire
Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition.
Coal liquefaction
Coal liquefaction is a process of converting coal into liquid hydrocarbons: liquid fuels and petrochemicals. This process is often known as "Coal to X", where X can be many different hydrocarbon-based products. However, the most common process chain is "Coal to Liquid Fuels" (CTL).
Waste management
Pyrolysis is often used to convert many types of domestic and industrial residues into a recovered fuel. Different types of waste input (such as plant waste, food waste, tyres) placed in the pyrolysis process potentially yield an alternative to fossil fuels. Pyrolysis is a process of thermo-chemical decomposition of organic materials by heat in the absence of stoichiometric quantities of oxygen; the decomposition produces various hydrocarbon gases. During pyrolysis, the molecules of object vibrate at high frequencies to an extent that molecules start breaking down. The rate of pyrolysis increases with temperature. In industrial applications, temperatures are above 430 °C (800 °F). Slow pyrolysis produces gases and solid charcoal. Pyrolysis hold promise for conversion of waste biomass into useful liquid fuel. Pyrolysis of waste wood and plastics can potentially produce fuel. The solids left from pyrolysis contain metals, glass, sand and pyrolysis coke which does not convert to gas. Compared to the process of incineration, certain types of pyrolysis processes release less harmful by-products that contain alkali metals, sulphur, and chlorine. However, pyrolysis of some waste yields gasses which impact the environment such as HCl and SO.
Phlogiston theory
The phlogiston theory is a superseded scientific theory that postulated that a fire-like element called phlogiston is contained within combustible bodies and released during combustion. The name comes from the Ancient Greek φλογιστόν "phlogistón" ("burning up"), from φλόξ "phlóx" ("flame"). It was first stated in 1667 by Johann Joachim Becher, and then put together more formally by Georg Ernst Stahl. The theory attempted to explain processes such as combustion and rusting, which are now collectively known as oxidation.
Engine
Combustion engines are heat engines driven by the heat of a combustion process.
Combustion
Adherence to these two principles is furthered by making material and heat balances on the combustion process. The material balance directly relates the air/fuel ratio to the percentage of in the combustion gas. The heat balance relates the heat available for the charge to the overall net heat produced by fuel combustion. Additional material and heat balances can be made to quantify the thermal advantage from preheating the combustion air, or enriching it in oxygen.
Barking dog reaction
In simple terms, the ‘Barking Dog’ reaction is a combustion process, in which a fuel (carbon disulfide, CS) reacts with an oxidizing agent (nitrous oxide, NO), producing heat and elemental sulfur. The flame front in the reaction is a zone of very hot, luminous gas, produced by the reactants decomposing.
Antoine Lavoisier
The relationship between combustion and respiration had long been recognized from the essential role which air played in both processes. Lavoisier was almost obliged, therefore, to extend his new theory of combustion to include the area of respiration physiology. His first memoirs on this topic were read to the Academy of Sciences in 1777, but his most significant contribution to this field was made in the winter of 1782/1783 in association with Laplace. The result of this work was published in a memoir, "On Heat." Lavoisier and Laplace designed an ice calorimeter apparatus for measuring the amount of heat given off during combustion or respiration. The outer shell of the calorimeter was packed with snow, which melted to maintain a constant temperature of around an inner shell filled with ice. By measuring the quantity of carbon dioxide and heat produced by confining a live guinea pig in this apparatus, and by comparing the amount of heat produced when sufficient carbon was burned in the ice calorimeter to produce the same amount of carbon dioxide as that which the guinea pig exhaled, they concluded that respiration was in fact a slow combustion process. Lavoisier stated, ""la respiration est donc une combustion,"" that is, respiratory gas exchange is a combustion, like that of a candle burning.
Pyrolysis
Pyrolysis is most commonly used to the treatment of organic materials. It is one of the processes involved in charring wood. In general, pyrolysis of organic substances produces volatile products and leaves a solid residue enriched in carbon, char. Extreme pyrolysis, which leaves mostly carbon as the residue, is called carbonization.
Combustor
This is the main combustion air. It is highly compressed air from the high-pressure compressor (often decelerated via the diffuser) that is fed through the main channels in the dome of the combustor and the first set of liner holes. This air is mixed with fuel, and then combusted.
Intermediate air is the air injected into the combustion zone through the second set of liner holes (primary air goes through the first set). This air completes the reaction processes, cooling the air down and diluting the high concentrations of carbon monoxide (CO) and hydrogen (H).
Dilution air is airflow injected through holes in the liner at the end of the combustion chamber to help cool the air to before it reaches the turbine stages. The air is carefully used to produce the uniform temperature profile desired in the combustor. However, as turbine blade technology improves, allowing them to withstand higher temperatures, dilution air is used less, allowing the use of more combustion air.
Cooling air is airflow that is injected through small holes in the liner to generate a layer (film) of cool air to protect the liner from the combustion temperatures. The implementation of cooling air has to be carefully designed so it does not directly interact with the combustion air and process. In some cases, as much as 50% of the inlet air is used as cooling air. There are several different methods of injecting this cooling air, and the method can influence the temperature profile that the liner is exposed to (see "Liner", above).
Combustion models for CFD
Computational fluid dynamics modeling of combustion calls upon the proper selection and implementation of a model suitable to faithfully represent the complex physical and chemical phenomenon associated with any combustion process. The model should be competent enough to deliver information related to the species concentration, their volumetric generation or destruction rate and changes in the parameters of the system like enthalpy, temperature and mixture density. The model should be capable of solving the general transport equations for fluid flow and heat transfer as well as the additional equations of combustion chemistry and Chemical kinetics incorporated into that as per the simulating environment desired
Decarboxylation
The term "decarboxylation" literally means removal of a carboxyl group (-COOH) and its replacement with a hydrogen atom. The term relates the state of the reactant and product. Decarboxylation is one of the oldest known organic reactions, since it often entails simple pyrolysis, and volatile products distilled from the reactor. Heating is required because the reaction is less favorable at low temperatures. Yields are highly sensitive to conditions. In retrosynthesis, decarboxylation reactions can be considered the opposite of homologation reactions, in that the chain length becomes one carbon shorter. Metals, especially copper compounds, are usually required. Such reactions proceed via the intermediacy of metal carboxylate complexes.
Bio-energy with carbon capture and storage
Pre-combustion carbon capture refers to the process of capturing CO before the energy generations. It is often composed of five operating stations: oxygen generation, syngas generation, CO separation, CO compression, and power generation. Basically, the fuel will first go through a gasification process by reacting with oxygen to form a stream of CO and H, which is syngas. The products will then go through a water-gas shift reactor to form CO and H. The CO that is produced will then be captured, and the H, which is a clean source, will be used for combustion to generate energy. The process of gasification combined with syngas production is called Integrated Gasification Combined Cycle (IGCC). Normally, it would require an Air Separation Unit (ASU) to serve as the oxygen source. However, research proves that with the same flue gas, oxygen gasification has little advantage over air gasification, and they both have a similar thermal efficiency of roughly 70% using coal as the fuel source. Thus, the use of ASU is not really necessary in pre-combustion.
Pulverized coal-fired boiler
The concept of burning coal that has been pulverized into a fine powder stems from the belief that if the coal is made fine enough, it will burn almost as easily and efficiently as a gas. The feeding rate of coal according to the boiler demand and the amount of air available for drying and transporting the pulverized coal fuel is controlled by computers. Pieces of coal are crushed between balls or cylindrical rollers that move between two tracks or "races." The raw coal is then fed into the pulverizer along with air heated to about 650°F / 340°C from the boiler. As the coal gets crushed by the rolling action, the hot air dries it and blows the usable fine coal powder out to be used as fuel. The powdered coal from the pulverizer is directly blown to a burner in the boiler. The burner mixes the powdered coal in the air suspension with additional pre-heated combustion air and forces it out of a nozzle similar in action to fuel being atomized by a fuel injector in modern cars. Under operating conditions, there is enough heat in the combustion zone to ignite all the incoming fuel.
Cofiring
Co-firing (also referred to as complementary firing or co-combustion) is the combustion of two different fuels in the same combustion system. Fuels can be solid fuels, liquid fuels or gaseous, and its source either fossil or renewable. Therefore, use of heavy fuel oil assisting coal power stations may technically be considered co-firing. However, the term co-firing is used in the present technological framework to designate combined combustion of two (or more) fuels sustained in time, as a normal daily practice.
Combustion
Combustion of a liquid fuel in an oxidizing atmosphere actually happens in the gas phase. It is the vapor that burns, not the liquid. Therefore, a liquid will normally catch fire only above a certain temperature: its flash point. The flash point of a liquid fuel is the lowest temperature at which it can form an ignitable mix with air. It is the minimum temperature at which there is enough evaporated fuel in the air to start combustion.
Combustion pipette
A combustion pipette is an apparatus for the reaction of liquids under a mild electric current and a supply of oxygen. In this experiment the test solution is a mixture of agar and oxalic acid in the presence of an electrolyte called cadmium chloride and an oxidant potassium permanganate. The voltage applied is 105VDC and a current of about 300mADC.
Combustion
Rapid combustion is a form of combustion, otherwise known as a fire, in which large amounts of heat and light energy are released, which often results in a flame. This is used in a form of machinery such as internal combustion engines and in thermobaric weapons. Such a combustion is frequently called an explosion, though for an internal combustion engine this is inaccurate. An internal combustion engine nominally operates on a controlled rapid burn. When the fuel-air mixture in an internal combustion engine explodes, that is known as detonation.
Combustion
The rate of combustion is the amount of a material that undergoes combustion over a period of time. It can be expressed in grams per second (g/s) or kilograms per second (kg/s).
Smoke
Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires (including stoves, candles, oil lamps, and fireplaces), but may also be used for pest control (fumigation), communication (smoke signals), defensive and offensive capabilities in the military (smoke screen), cooking, or smoking (tobacco, cannabis, etc.). It is used in rituals where incense, sage, or resin is burned to produce a smell for spiritual purposes. Smoke is sometimes used as a flavoring agent, and preservative for various foodstuffs. Smoke is also a component of internal combustion engine exhaust gas, particularly diesel exhaust.
Simple chemical reacting system
The simple chemical reacting system (SCRS) is one of the combustion models for computational fluid dynamics. This model helps us to determine the process of combustion which is a vital phenomenon used in many engineering applications like aircraft engines, internal combustion engines, rocket engines, industrial furnaces, and power station combustors. The simple chemical reacting system (SCRS) refers the global nature of the combustion process considering only the final species concentrations. The detailed kinetics of the process is generally neglected and it postulates that combustion does proceed via a global one-step without intermediates. Infinitely fast chemical reaction is assumed with oxidants reacting in stoichiometric proportions to form products. SCRS considers the reaction to be irreversible i.e. rate of reverse reaction is presumed to be very low.
Heat of combustion
Another definition, used by Gas Processors Suppliers Association (GPSA) and originally used by API (data collected for API research project 44), is the enthalpy of all combustion products minus the enthalpy of the fuel at the reference temperature (API research project 44 used 25 °C. GPSA currently uses 60 °F), minus the enthalpy of the stoichiometric oxygen (O) at the reference temperature, minus the heat of vaporization of the vapor content of the combustion products.
Fluidized bed combustion
Fluidized-bed combustion evolved from efforts to find a combustion process able to control pollutant emissions without external emission controls (such as scrubbers-flue gas desulfurization). The technology burns fuel at temperatures of 1,400 to 1,700 °F (750-900 °C), well below the threshold where nitrogen oxides form (at approximately 2,500 °F / 1400 °C, the nitrogen and oxygen atoms in the combustion air combine to form nitrogen oxide pollutants); it also avoids the ash melting problems related to high combustion temperature. The mixing action of the fluidized bed brings the flue gases into contact with a sulfur-absorbing chemical, such as limestone or dolomite. More than 95% of the sulfur pollutants in coal can be captured inside the boiler by the sorbent. The reductions may be less substantial than they seem, however, as they coincide with dramatic increases in carbon (monoxide?) and polycyclic aromatic hydrocarbons emissions.
Charring
Charring is a chemical process of incomplete combustion of certain solids when subjected to high heat. The resulting residue matter is called char. By the action of heat, charring removes hydrogen and oxygen from the solid, so that the remaining char is composed primarily of carbon. Polymers like thermoset, or most solid organic compounds like wood or biological tissue, exhibit charring behaviour.
Combustion
Uncatalyzed combustion in air requires fairly high temperatures. Complete combustion is stoichiometric with respect to the fuel, where there is no remaining fuel, and ideally, no remaining oxidant. Thermodynamically, the chemical equilibrium of combustion in air is overwhelmingly on the side of the products. However, complete combustion is almost impossible to achieve, since the chemical equilibrium is not necessarily reached, or may contain unburnt products such as carbon monoxide, hydrogen and even carbon (soot or ash). Thus, the produced smoke is usually toxic and contains unburned or partially oxidized products. Any combustion at high temperatures in atmospheric air, which is 78 percent nitrogen, will also create small amounts of several nitrogen oxides, commonly referred to as , since the combustion of nitrogen is thermodynamically favored at high, but not low temperatures. Since combustion is rarely clean, flue gas cleaning or catalytic converters may be required by law.
Chemical thermodynamics
Another useful term is the heat of combustion, which is the energy released due to a combustion reaction and often applied in the study of fuels. Food is similar to hydrocarbon fuel and carbohydrate fuels, and when it is oxidized, its caloric content is similar (though not assessed in the same way as a hydrocarbon fuel — see food energy).
Combustion
Combustion of gaseous fuels may occur through one of four distinctive types of burning: diffusion flame, premixed flame, autoignitive reaction front, or as a detonation. The type of burning that actually occurs depends on the degree to which the fuel and oxidizer are mixed prior to heating: for example, a diffusion flame is formed if the fuel and oxidizer are separated initially, whereas a premixed flame is formed otherwise. Similarly, the type of burning also depends on the pressure: a detonation, for example, is an autoignitive reaction front coupled to a strong shock wave giving it its characteristic high-pressure peak and high detonation velocity.
Combustion
Most commonly, the adiabatic combustion temperatures for coals are around (for inlet air and fuel at ambient temperatures and for formula_10), around for oil and for natural gas.
Combustion Resources
Combustion Resources worked under a grant from the US Department of Energy to research and optimize current designs of shale oil extraction. It seeked to eliminate carbon dioxide emissions from the shale oil production process. Pyrolysis occurs in a rotating kiln heated by hot gas flowing through an outer annulus. The hot gas is created by burning hydrogen generated in a separate unit by coal gasification followed by carbon dioxide separation. The geometry of the annulus enables the transfer of heat to the moving shale through a wall.
Emergency oxygen system
Combustion is the exothermic chemical reaction between oxygen and a fuel, producing a flame and smoke. Because oxygen is necessary to fuel a fire, oxygen-generating equipment on aircraft pose a significant fire hazard and have contributed to several aircraft fires, both on the ground and while in flight.
Combustion (film)
Combustion () is a 2013 Spanish action film directed by Daniel Calparsoro.
Heterogeneous combustion
Heterogeneous combustion, otherwise known as combustion in porous media, is a type of combustion in which a solid and gas phase interact to promote the complete transfer of reactants to their lower energy potential products. In this type of combustion a high surface area solid is immersed into a gaseous reacting flow, additional fluid phases may or may not be present. Chemical reactions and heat transfer occur locally on each phase and between both phases. Heterogeneous Combustion differs from catalysis as there is no focus to either phase individually but rather both examined simultaneously. In some materials, such as silicon carbide (SiC), oxide layers, SiO and SiO, which form on the surface enable the adsorption of water vapor from the gas phase onto the solid lowering partial pressures.
In this regime of combustion, thermal heat released from the combustion byproducts are transferred into the solid phase by convection; conduction and radiation both then conduct heat upstream (along with adverse convection within the gas phase). Heat is then convectively transferred to the unburnt reactants.
Biomass briquettes
Cofiring relates to the combustion of two different types of materials. The process is primarily used to decrease CO emissions despite the resulting lower energy efficiency and higher variable cost. The combination of materials usually contains a high carbon emitting substance such as coal and a lesser CO emitting material such as biomass. Even though CO will still be emitted through the combustion of biomass, the net carbon emitted is nearly negligible. This is due to the fact that the material gathered for the composition of the briquettes are still contained in the carbon cycle whereas fossil fuel combustion releases CO that has been sequestered for millennia. Boilers in power plants are traditionally heated by the combustion of coal, but if cofiring were to be implemented, then the CO emissions would decrease while still maintaining the heat inputted to the boiler. Implementing cofiring would require few modifications to the current characteristics to power plants, as only the fuel for the boiler would be altered. A moderate investment would be required for implementing biomass briquettes into the combustion process.
Combustion
Substances or materials which undergo combustion are called fuels. The most common examples are natural gas, propane, kerosene, diesel, petrol, charcoal, coal, wood, etc.
Homogeneous charge compression ignition
A mixture of fuel and air ignites when the concentration and temperature of reactants is sufficiently high. The concentration and/or temperature can be increased in several different ways:Once ignited, combustion occurs very quickly. When auto-ignition occurs too early or with too much chemical energy, combustion is too fast and high in-cylinder pressures can destroy an engine. For this reason, HCCI is typically operated at lean overall fuel mixtures.
HCCI is more difficult to control than other combustion engines, such as SI and diesel. In a typical gasoline engine, a spark is used to ignite the pre-mixed fuel and air. In Diesel engines, combustion begins when the fuel is injected into pre-compressed air. In both cases, combustion timing is explicitly controlled. In an HCCI engine, however, the homogeneous mixture of fuel and air is compressed and combustion begins whenever sufficient pressure and temperature are reached. This means that no well-defined combustion initiator provides direct control. Engines must be designed so that ignition conditions occur at the desired timing. To achieve dynamic operation, the control system must manage the conditions that induce combustion. Options include the compression ratio, inducted gas temperature, inducted gas pressure, fuel-air ratio, or quantity of retained or re-inducted exhaust. Several control approaches are discussed below.
Combustor
A combustor must contain and maintain stable combustion despite very high air flow rates. To do so combustors are carefully designed to first mix and ignite the air and fuel, and then mix in more air to complete the combustion process. Early gas turbine engines used a single chamber known as a can type combustor. Today three main configurations exist: can, annular and cannular (also referred to as can-annular tubo-annular). Afterburners are often considered another type of combustor.
Coal burner
A coal burner (or pulverized coal burner) is a mechanical device that burns pulverized coal (also known as powdered coal or coal dust since it is as fine as face powder in cosmetic makeup) into a flame in a controlled manner.
Coal burner is mainly composed of pulverized coal machine, host of combustion machine (including combustion chamber, automatic back and forth motion system, automatic rotation system, the combustion air supply system) control system, ignition system, the crater and others.
Combustion
In most industrial applications and in fires, air is the source of oxygen (). In the air, each mole of oxygen is mixed with approximately of nitrogen. Nitrogen does not take part in combustion, but at high temperatures some nitrogen will be converted to  (mostly , with much smaller amounts of ). On the other hand, when there is insufficient oxygen to completely combust the fuel, some fuel carbon is converted to carbon monoxide and some of the hydrogen remains unreacted. A more complete set of equations for the combustion of a hydrocarbon in the air, therefore, requires an additional calculation for the distribution of oxygen between the carbon and hydrogen in the fuel.
Radical (chemistry)
Combustion consists of various radical chain reactions that the singlet radical can initiate. The flammability of a given material strongly depends on the concentration of radicals that must be obtained before initiation and propagation reactions dominate leading to combustion of the material. Once the combustible material has been consumed, termination reactions again dominate and the flame dies out. As indicated, promotion of propagation or termination reactions alters flammability. For example, because lead itself deactivates radicals in the gasoline-air mixture, tetraethyl lead was once commonly added to gasoline. This prevents the combustion from initiating in an uncontrolled manner or in unburnt residues (engine knocking) or premature ignition (preignition).
Combustion
The quality of combustion can be improved by the designs of combustion devices, such as burners and internal combustion engines. Further improvements are achievable by catalytic after-burning devices (such as catalytic converters) or by the simple partial return of the exhaust gases into the combustion process. Such devices are required by environmental legislation for cars in most countries and may be necessary to enable large combustion devices, such as thermal power stations, to reach legal emission standards.
Oxy-fuel combustion process
Oxy-fuel combustion is the process of burning a fuel using pure oxygen instead of air as the primary oxidant. Since the nitrogen component of air is not heated, fuel consumption is reduced, and higher flame temperatures are possible. Historically, the primary use of oxy-fuel combustion has been in welding and cutting of metals, especially steel, since oxy-fuel allows for higher flame temperatures than can be achieved with an air-fuel flame.
Surface Combustion
Surface combustion is an engineering term which refers to process whereby a gaseous fuel is premixed with enough oxygen so that both the fuel and the oxygen are nearly completely used up.
Charring
Charring can result from naturally occurring processes like fire; it is also a deliberate and controlled reaction used in the manufacturing of certain products. The mechanism of charring is part of the normal burning of certain solid fuels like wood. During normal combustion, the volatile compounds created by charring are consumed at the flames within the fire or released to the atmosphere, while combustion of char can be seen as glowing red coals or embers which burn without the presence of flames.
Eddy break-up model
The eddy break-up model (EBU) is used in combustion engineering. 
Combustion modeling has a wide range of applications. In most of the combustion systems fuel and oxygen (or air) are separately supplied in the combustion chamber. Due to this chemical reaction and combustion occurs simultaneously in the combustion chamber. However, the rate of the chemical reaction is faster than the rate of mixing fuel and oxygen. Therefore, that rate of combustion is controlled by rate of mixing. Such cases, where formation of pre-mixture is difficult, are called diffusion combustion or diffusion flames.
Catalytic combustion
Catalytic combustion is a chemical process which uses a catalyst to speed desired oxidation reactions of a fuel and so reduce the formation of undesired products, especially pollutant nitrogen oxide gases (NO) far below what can be achieved without catalysts. The process was discovered in the 1970s at Engelhard Corp.
Cool flame
Whereas in a usual flame molecules break down to small fragments and combine with oxygen producing carbon dioxide (i.e. burn), in a cool flame, the fragments are relatively large and easily recombine with each other. Therefore, much less heat, light and carbon dioxide is released; the combustion process is oscillatory and can sustain for a long time. A typical temperature increase upon ignition of a cool flame is a few tens of degrees Celsius whereas it is on the order of 1000 °C for a conventional flame.
Combustor
Can combustors are self-contained cylindrical combustion chambers. Each "can" has its own fuel injector, igniter, liner, and casing. The primary air from the compressor is guided into each individual can, where it is decelerated, mixed with fuel, and then ignited. The secondary air also comes from the compressor, where it is fed outside of the liner (inside of which is where the combustion is taking place). The secondary air is then fed, usually through slits in the liner, into the combustion zone to cool the liner via thin film cooling.
Engine
"Combustion" refers to burning fuel with an oxidizer, to supply the heat. Engines of similar (or even identical) configuration and operation may use a supply of heat from other sources such as nuclear, solar, geothermal or exothermic reactions not involving combustion; but are not then strictly classed as external combustion engines, but as external thermal engines.
Smouldering
The fundamental difference between smouldering and flaming combustion is that smouldering occurs on the surface of the solid rather than in the gas phase. Smouldering is a surface phenomenon but can propagate to the interior of a porous fuel if it is permeable to flow. The characteristic temperature and heat released during smouldering are low compared to those in the flaming combustion (i.e., ~ vs. ~). Smouldering propagates in a creeping fashion, around , which is about ten times slower than flames spread over a solid. In spite of its weak combustion characteristics, smouldering is a significant fire hazard. Smouldering emits toxic gases (e.g., carbon monoxide) at a higher yield than flaming fires and leaves behind a significant amount of solid residue. The emitted gases are flammable and could later be ignited in the gas phase, triggering the transition to flaming combustion.
Gas combustion retort process
Crushed raw oil shale is fed into the top of the retort, and it moves downward by gravity. When moving downward, oil shale is heated by the rising recycled gases, which cause decomposition of the rock. Recycled gases enter the retort from the bottom. Gases are heated on the lower part of retort by descended spent shale. On their way up, gases move through the combustion zone, where air and dilution gases are injected causing combustion of gases and carbonaceous residue of spent shale (char). The heat from combustion brings the temperature in the retorting zone above of the burning zone to the necessary level for retorting. The incoming raw oil shale cool oil vapors and gases, which then leave the top of the retort as a mist.
Combustion
In the case of fossil fuels burnt in air, the combustion temperature depends on all of the following:
External combustion engine
"Combustion" refers to burning fuel with an oxidizer, to supply the heat. Engines of similar (or even identical) configuration and operation may use a supply of heat from other sources such as nuclear, solar, geothermal or exothermic reactions not involving combustion; they are not then strictly classed as external combustion engines, but as external thermal engines.
Deflagration
Deflagration (Lat: "de + flagrare", "to burn down") is subsonic combustion propagating through heat transfer; hot burning material heats the next layer of cold material and ignites it. Most "fires" found in daily life, from flames to explosions such as that of Black powder, are deflagrations. This differs from detonation, which propagates supersonically through shock waves, decomposing a substance extremely quickly.
Methane
Methane's heat of combustion is 55.5 MJ/kg. Combustion of methane is a multiple step reaction summarized as follows:
Peters four-step chemistry is a systematically reduced four-step chemistry which explains the burning of methane.
Valveless pulsejet
The combustion events driving a pulsejet are often informally called explosions; however, the correct term is deflagrations. They are not detonations, which is the combustion event in Pulse Detonation Engines (PDEs). The deflagration within the combustion zone of a pulsejet is characterized by a sudden rise in temperature and pressure followed by a rapid subsonic expansion in gas volume. It is this expansion that performs the main work of moving air rearward through the device as well as setting up conditions in the main tube for the cycle to continue.
Exothermic process
Simply stated, after an exothermic reaction, more energy has been released to the surroundings than was absorbed to initiate and maintain the reaction. An example would be the burning of a candle, wherein the sum of calories produced by combustion (found by looking at radiant heating of the surroundings and visible light produced, including increase in temperature of the fuel (wax) itself, which with oxygen, have become hot CO and water vapor,) exceeds the number of calories absorbed initially in lighting the flame and in the flame maintaining itself. (i.e. some energy produced by combustion is reabsorbed and used in melting, then vaporizing the wax, etc. but is (far) outstripped by the energy produced in breaking carbon-hydrogen bonds and combination of oxygen with the resulting carbon and hydrogen).
Carburizing
Early carburization used a direct application of charcoal packed around the sample to be treated (initially referred to as case hardening), but modern techniques use carbon-bearing gases or plasmas (such as carbon dioxide or methane). The process depends primarily upon ambient gas composition and furnace temperature, which must be carefully controlled, as the heat may also impact the microstructure of the remainder of the material. For applications where great control over gas composition is desired, carburization may take place under very low pressures in a vacuum chamber.
Fire
A flame is a mixture of reacting gases and solids emitting visible, infrared, and sometimes ultraviolet light, the frequency spectrum of which depends on the chemical composition of the burning material and intermediate reaction products. In many cases, such as the burning of organic matter, for example wood, or the incomplete combustion of gas, incandescent solid particles called soot produce the familiar red-orange glow of "fire". This light has a continuous spectrum. Complete combustion of gas has a dim blue color due to the emission of single-wavelength radiation from various electron transitions in the excited molecules formed in the flame. Usually oxygen is involved, but hydrogen burning in chlorine also produces a flame, producing hydrogen chloride (HCl). Other possible combinations producing flames, amongst many, are fluorine and hydrogen, and hydrazine and nitrogen tetroxide. Hydrogen and hydrazine/UDMH flames are similarly pale blue, while burning boron and its compounds, evaluated in mid-20th century as a high energy fuel for jet and rocket engines, emits intense green flame, leading to its informal nickname of "Green Dragon".
Petrochemistry
Refineries then execute processes that cause various physical and chemical changes in the crude oil and natural gas. This involves extremely specialized manufacturing processes. One of the important process is distillation, i.e., separation of heavy crude oil into lighter groups (called fractions) of hydrocarbons. There are two processes of distillation: CDU process and VDU process. The objective of the CDU process is to distill and separate valuable distillates (naphtha, kerosene, diesel) and atmospheric gas oil (AGO) from the crude feedstock. The technique used to carry out the above process is called complex distillation. On the other hand, the objective of the VDU process is to recover valuable gas oils from reduced crude via vacuum distillation. Two of the fractions of distillation are fuel oil and naphtha, which are familiar to consumers. Fuel oil, is used for heating for diesel fuel in automotive applications. Naphtha is used in gasoline and also used as the primary source for petrochemicals.
Clarke's equation
In combustion, Clarke's equation is a third-order nonlinear partial differential equation, first derived by John Frederick Clarke in 1978. The equation describes the thermal explosion process, including both effects of constant-volume and constant-pressure processes, as well as the effects of adiabatic and isothermal sound speeds. The equation reads as
Charring
Coke and charcoal are both produced by charring, whether on an industrial scale or through normal combustion of coal or wood. Normal combustion consumes the char as well as the gases produced in its creation, while industrial processes seek to recover the purified char with minimal loss to combustion. This is accomplished by either burning the parent fuel (wood or coal) in a low-oxygen environment or by heating it to a high temperature without allowing combustion to occur. In industrial production of coke and charcoal the volatile compounds driven off during charring are often captured for use in other chemical processes.
Chemical energy
Another useful term is the heat of combustion, which is the energy mostly of the weak double bonds of molecular oxygen released due to a combustion reaction and often applied in the study of fuels. Food is similar to hydrocarbon and carbohydrate fuels, and when it is oxidized to carbon dioxide and water, the energy released is analogous to the heat of combustion (though not assessed in the same way as a hydrocarbon fuel — see food energy).
Adiabatic flame temperature
We see that the adiabatic flame temperature of the constant pressure process is lower than that of the constant volume process. This is because some of the energy released during combustion goes into changing the volume of the control system. One analogy that is commonly made between the two processes is through combustion in an internal combustion engine. For the constant volume adiabatic process, combustion is thought to occur instantaneously when the piston reaches the top of its apex (Otto cycle or constant volume cycle). For the constant pressure adiabatic process, while combustion is occurring the piston is moving in order to keep the pressure constant (Diesel cycle or constant pressure cycle).
Engine
The internal combustion engine is an engine in which the combustion of a fuel (generally, fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber. In an internal combustion engine the expansion of the high temperature and high pressure gases, which are produced by the combustion, directly applies force to components of the engine, such as the pistons or turbine blades or a nozzle, and by moving it over a distance, generates mechanical work.
Combustion (software)
Combustion was a computer program for motion graphics, compositing and visual effects.
It is commonly likened to Adobe's After Effects, and shares a timeline based interface with Autodesk Media and Entertainment's (formerly "Discreet") higher-end compositing systems Inferno, Flame and Flint. This is in contrast to the node based interface used by some other compositing applications.
Combustion
Spontaneous combustion is a type of combustion which occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self-heating which rapidly accelerates to high temperatures) and finally, ignition.
For example, phosphorus self-ignites at room temperature without the application of heat. Organic materials undergoing bacterial composting can generate enough heat to reach the point of combustion.
Combustion models for CFD
The major consideration during any general combustion process includes the mixing time scale and the reacting time scale elapsed for the process. The flame type and the type of mixing of flow streams of the constituents also have to be taken into account. Apart from that as far as the kinetic complexity of the reaction is concerned, the reaction proceeds in multiple steps and what appears as a simple one line reaction actually completes after a series of reactions. Also the transport equations for mass fractions of all the species as well as the enthalpy generated during the reaction have to be solved. Hence even the simplest combustion reaction involves very tedious and rigorous calculation if all the intermediate steps of the combustion process, all transport equations and all flow equations have to be satisfied simultaneously. All these factors will have a significant effect on the computational speed and time of the simulation. But with proper simplifying assumptions Computational fluid dynamic modeling of combustion reaction can be done without substantial compromise on the accuracy and convergence of the solution. The basic models used for the same are covered in the following paragraphs.
Burning (disambiguation)
Burning is combustion, a high-temperature reaction between a fuel and an oxidant.
Combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion in a fire produces a flame, and the heat produced can make combustion self-sustaining. Combustion is often a complicated sequence of elementary radical reactions. Solid fuels, such as wood and coal, first undergo endothermic pyrolysis to produce gaseous fuels whose combustion then supplies the heat required to produce more of them. Combustion is often hot enough that incandescent light in the form of either glowing or a flame is produced. A simple example can be seen in the combustion of hydrogen and oxygen into water vapor, a reaction commonly used to fuel rocket engines. This reaction releases 242 kJ/mol of heat and reduces the enthalpy accordingly (at constant temperature and pressure):
Proceedings of the Combustion Institute
The Proceedings of the Combustion Institute are the proceedings of the biennial Combustion Symposium put on by The Combustion Institute. The publication contains the most significant contributions in fundamentals and applications fundamental research of combustion science combustion phenomena. Research papers and invited topical reviews are included on topics of reaction kinetics, soot, PAH and other large molecules, diagnostics, laminar flames, turbulent flames, heterogenous combustion, spray and droplet combustion, detonations, explosions & supersonic combustion, fire research, stationary combustion systems, internal combustion engine and gas turbine combustion, and new technology concepts. The editors-in-chief are Volker Sick (University of Michigan) and Alison Tomlin (University of Leeds).
Combustion
In a perfect furnace, the combustion air flow would be matched to the fuel flow to give each fuel molecule the exact amount of oxygen needed to cause complete combustion. However, in the real world, combustion does not proceed in a perfect manner. Unburned fuel (usually and ) discharged from the system represents a heating value loss (as well as a safety hazard). Since combustibles are undesirable in the offgas, while the presence of unreacted oxygen there presents minimal safety and environmental concerns, the first principle of combustion management is to provide more oxygen than is theoretically needed to ensure that all the fuel burns. For methane () combustion, for example, slightly more than two molecules of oxygen are required.
Ethane
Combustion occurs by a complex series of free-radical reactions. Computer simulations of the chemical kinetics of ethane combustion have included hundreds of reactions. An important series of reaction in ethane combustion is the combination of an ethyl radical with oxygen, and the subsequent breakup of the resulting peroxide into ethoxy and hydroxyl radicals.
Premixed flame
A premixed flame is a flame formed under certain conditions during the combustion of a premixed charge (also called pre-mixture) of fuel and oxidiser. Since the fuel and oxidiser—the key chemical reactants of combustion—are available throughout a homogeneous stoichiometric premixed charge, the combustion process once initiated sustains itself by way of its own heat release. The majority of the chemical transformation in such a combustion process occurs primarily in a thin interfacial region which separates the unburned and the burned gases. The premixed flame interface propagates through the mixture until the entire charge is depleted. The propagation speed of a premixed flame is known as the flame speed (or burning velocity) which depends on the convection-diffusion-reaction balance within the flame, i.e. on its inner chemical structure. The premixed flame is characterised as laminar or turbulent depending on the velocity distribution in the unburned pre-mixture (which provides the medium of propagation for the flame).
Nikolay Dobrokhotov
combustion of fuel at high temperatures is determined by the conditions of mixing it with oxygen. The chemical reaction of combustion occurs very quickly and does not limit the rate of fuel combustion process;
Inexact differential
A fire requires heat, fuel, and an oxidizing agent. The energy required to overcome the activation energy barrier for combustion is transferred as heat into the system, resulting in changes to the system’s internal energy. In a process, the energy input to start a fire may comprise both work and heat, such as when one rubs tinder (work) and experiences friction (heat) to start a fire. The ensuing combustion is highly exothermic, which releases heat. The overall change in internal energy does not reveal the mode of energy transfer and quantifies only the net work and heat. The difference between initial and final states of the system’s internal energy does not account for the extent of the energy interactions transpired. Therefore, internal energy is a state function (i.e. exact differential), while heat and work are path functions (i.e. inexact differentials) because integration must account for the path taken.
Internal combustion engine
An internal combustion engine (ICE) is a heat engine where the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is applied typically to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy.
Micro-combustion
Micro-combustion is the sequence of exothermic chemical reaction between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species at micro level. The release of heat can result in the production of light in the form of either glowing or a flame. Fuels of interest often include organic compounds (especially hydrocarbons) in the gas, liquid or solid phase. The major problem of micro-combustion is the high surface to volume ratio. As the surface to volume ratio increases heat loss to walls of combustor increases which leads to flame quenching.
Ember
An ember is formed when a fire has only partially burnt a piece of fuel, and there is still usable chemical energy in that piece of fuel. This happens because the usable chemical energy is so deep into the center that air (specifically oxygen) does not reach it, therefore not causing combustion (carbon-based fuel + O → CO + HO + C + other chemicals involved). It continues to stay hot and does not lose its thermal energy quickly because combustion is still happening at a low level. The small yellow, orange and red lights often seen among the embers are actually combustion. There just is not enough combustion happening at one time to create a flame. Once the embers are completely 'burned through', they are not carbon as is commonly believed (carbon burns, and is not normally left behind), but rather various other oxidized minerals like calcium and phosphorus. At that point they are normally called ashes. See: Wood ash for more on the residue that is left.
Propane
Propane combustion is much cleaner than unleaded gasoline combustion, and cleaner than natural gas combustion, because of the extremely high hydrogen content in propane. Propane burns hotter than home heating oil or diesel fuel because of the very high hydrogen content. Natural gas, known as methane shipped to your home or office, doesn't have the high hydrogen content of propane as used in North America. The presence of C–C bonds, plus the multiple bonds of propylene and butylene, create organic exhausts besides carbon dioxide and water vapor during typical combustion. These bonds also cause propane to burn with a visible flame.
Internal combustion engine
Not all of the fuel is completely consumed by the combustion process. A small amount of fuel is present after combustion, and some of it reacts to form oxygenates, such as formaldehyde or acetaldehyde, or hydrocarbons not originally present in the input fuel mixture. Incomplete combustion usually results from insufficient oxygen to achieve the perfect stoichiometric ratio. The flame is "quenched" by the relatively cool cylinder walls, leaving behind unreacted fuel that is expelled with the exhaust. When running at lower speeds, quenching is commonly observed in diesel (compression ignition) engines that run on natural gas. Quenching reduces efficiency and increases knocking, sometimes causing the engine to stall. Incomplete combustion also leads to the production of carbon monoxide (CO). Further chemicals released are benzene and 1,3-butadiene that are also hazardous air pollutants.
Combustion analysis
Combustion analysis is a method used in both organic chemistry and analytical chemistry to determine the elemental composition (more precisely empirical formula) of a pure organic compound by combusting the sample under conditions where the resulting combustion products can be quantitatively analyzed. Once the number of moles of each combustion product has been determined the empirical formula or a partial empirical formula of 
the original compound can be calculated.
Combustion chamber
A combustion chamber is that part of an internal combustion engine (ICE) or a reaction engine in which the fuel/air mix is burned.
Pyrolysis
Pyrolysis differs from other processes like combustion and hydrolysis in that it usually does not involve the addition of other reagents such as oxygen (O, in combustion) or water (in hydrolysis). In practice, it is often not practical to achieve completely O- or water-free conditions, especially as pyrolysis is often conducted on complex mixtures. The term has also been applied to the decomposition of organic material in the presence of superheated water or steam (hydrous pyrolysis), for example, in the steam cracking of oil. Pyrolysis has been assumed to take place during catagenesis, the conversion of buried organic matter to fossil fuels.