Combustion devices

Fuel-bound NO. is formed at low as well as high temperatures. However, part of the fuel nitrogen is directly reacted to N2. Moreover, N2O and N2O4 are also formed in various reactions and add to the complexity of the formation. It is virtually impossible to calculate a precise value for the NO, emitted by a real combustion device. NO, emissions depend not only on the type of combustion technology but also on its size and the type of fuel used. 

Fuel switch. Since formation is fuel-dependent, switching fuel can reduce formation. The general trend is that from solid to liquid to gaseous fuel, the formation decreases. However, it should be emphasized again that this is also very much dependent on the combustion device. 

T. J. Tyson, "The Mathematical Modeling of Combustion Devices," paper presented at Proceedings of the Stationary Source Combustion Symposium, Vol. 

Once an undesirable material is created, the most widely used approach to exhaust emission control is the appHcation of add-on control devices (6). Eor organic vapors, these devices can be one of two types, combustion or capture. AppHcable combustion devices include thermal iaciaerators (qv), ie, rotary kilns, Hquid injection combusters, fixed hearths, and uidi2ed-bed combustors catalytic oxidi2ation devices flares or boilers/process heaters. Primary appHcable capture devices include condensers, adsorbers, and absorbers, although such techniques as precipitation and membrane filtration ate finding increased appHcation. A comparison of the primary control alternatives is shown in Table 1 (see also Absorption Adsorption Membrane technology). 

Because of the high operating temperatures, the unit must be constructed of metals capable of withstanding this condition. Combustion devices are usually constructed with an outer steel shell that is lined with refractory material. Refraclory-waU thickness is usually in the... 

Surface combustion devices are designed for fully premixing the gaseous fuel and air and burning it on a porous radiant surface. The close coupling of the combustion process with the burner surface results in low flame temperatures and, consequently, low NO formation. Surface materials can include ceramic fibers, reticulated ceramics, and metal alloy mats. This approach allows the burner shape to be customized to match the heat transfer profile with the application. 

With a solid fuel, such as coal or wood, a series of steps are involved in combustion. These steps occur in a definite order, and the combustion device must be designed with these steps in mind. Figure 6-6 shows what happens to a typical solid fuel during the combustion process. 

Control technologies employed for the handling of air emissions normally include the capture and recycling or combustion of emissions from vents, product transfer points, storage tanks, and other handling equipment. Boilers, heaters, other combustion devices, cokers, and catalytic units may require paniculate matter controls. Use of a carbon monoxide boiler is normally a standard practice... 

Elevated Flares See Flares for a general definition. The elevated flare, by the use of steam injection and effective tip design, operates as a smokeless combustion device. Flaring generally is of low luminosity up to about 20 % of maximum flaring load. Steam injection tends to introduce a source of noise to the operation, and a compromise between smoke elimination and noise is usually necessary. When adequately elevated (by means of a stack) this type of flare displays the best dispersion characteristics for malodorous and toxic combustion products. Visual and noise pollution often creates nuisance problems. Capital and operating costs tend to be high, and an appreciable plant area can be rendered unavailable for plant operations and equipment because of excessive radiant heat. 

Combustion is the entire process by which something is oxidized. It is part of the use of gasoline or diesel fuel in automobiles and trucks, as well as part of propulsion in aircraft either in jet engines or propeller engines. This latter association is so often made that the propulsive devices in aircraft are called combustors. Similarly, furnaces and boilers, that often involve flames for the production of heat, are combustion devices involving many of the elements of the complete process. Incinerators, too, are commonly associated with combustion of fuel in the form of waste materials. Other common manifestations of coiiibustioii are house, forest, and chemical fires ... 

Carbon dioxide has been implicated as a contributing factor in global warming. Increased global warming has been associated with increased release of carbon dioxide into the atmosphere attributed in part to an increase in the combustion of hydrocarbon fuels. Carbon dioxide is an inevitable consequence of the complete combustion of hydrocarbons in air. If combustion devices are made more efficient, less fuel is required and less carbon dioxide is released into the atmosphere. 

Despite the fact that thermo-acoustic instabilihes have been studied for more than a century, their control and elimination in practical combustion devices is still a problem that is difficult to master, particularly in devices with a high energy density such as aero-engines and rocket propulsion systems [24-28]. 

The difficult part of the problem is to identify and describe the mechanism by which the acoustic wave modulates the combustion rate. There are many possible mechanisms by which an acoustic wave can influence combustion, and the dominant mechanism varies with the design of the combustion device. Possible coupling mechanisms include... 

Localized extinction of the flame surface can readily occur in the turbulent combustion devices, where wrinkled flames interact with turbulent eddies and gas... 

Combustion device used in the recovery of sulfur values from spent sulfuric acid. 

Molecular chlorine should not be used in the process. The effluent should not result in a temperature increase of more than 3 °C at the edge of the zone where initial mixing and dilution take place. Where the zone is not defined, 100 m from the point of discharge should be used. Solid wastes should be sent to combustion devices or disposed of in a manner that avoids odor generation and the release of toxic organics to the environment. 

Tier I The focal point of Tier I is the waste feed. This tier limits the hourly feed rate of individual metals into the combustion device. These limits have been developed by U.S. EPA and can be found in Part 266, Appendix I.5 U.S. EPA established these feed rate limits by considering flue gas flows, stack height, terrain, and land use in the vicinity of the facility. It determined acceptable air quality levels for each type of metal as a function of terrain, stack height, and land use in the vicinity of the facility. This value is also the waste feed rate, as Tier I assumes that 100% of the metals that are fed into the unit will be released into the atmosphere. 

Power-vented combustion devices or combustion devices that use outside air. 

The bathroom, laundry, and kitchen exhausts would have to operate as normally installed and enough pressurization air would have to be added so that the intermittent operation of these exhausts would not overcome the time-averaged benefits of house pressurization. Combustion products are probably not an issue because there is no combustion device in the house. 

Thus, the technique can become counterproductive. A typical arrangement for selective non-catalytic reduction is shown in Figure 25.30. Aqueous ammonia is vaporized and mixed with a carrier gas (low-pressure steam or compressed air) and injected into nozzles located in the combustion device for optimum temperature and residence time10. NO, reduction of up to 75% can be achieved. However, slippage of excess ammonia must be controlled carefully. 

Studies have been conducted to expose animals to a constant, known concentration of HC1 as produced from the combustion of PVC (3,12). Concentrations of HC1 were dependent upon other experimental parameters in addition to the amounts of PVC burned. Thus, the technique does not lend itself to determination of an LCM based on PVC. Estimates can be made, however, by referring to published data which were obtained using the continuous combustion device (12). 

Biomass combustion devices, 3 686-688 Biomass conversion, for hydrogen production, 73 784... 

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