Fire combustion cycle

Natural gas also has an efficiency advantage in electricity generation. The economic and operational superiority of gas-fired combustion turbines and combined-cycle machines (and prospectively, the superiority of gas-powered fuel cells) relative to coal-and nuclear-powered steam turbines made the combination of natural gas and natural gas turbines the supply favorite of most electric utilities in the 1990s. 

Sullivan, L.D., Klepels, J.E., Coderre, W.J., and Fischer, W.H., "Coal-Fired, Open Cycle MHD Combustion Plasmas Chemical Equilibrium and Transport Properties Workshop Results", Paper 80-0091, AIAA 18th Aerospace Sciences Meeting, Pasadena, California, January 1980. 

Brandvoll, 0. and Bolland, O. Inherent C02 capture using chemical looping combustion in a natural gas fired power cycle. Journal of Engineering for Gas Turbines and Power, 2002, 126, 316. 

High temperature ceramic heat exchangers (HX) either in tube-in-tube or plate type design are promising candidates for the use in harsh corrosive and combustion environments. In contrast to tubes, plate-lype HX with integrated flow channels can contribute to an increasing efficiency of the heat transfer. Those HX can be used for heat recovery processes, thermo chemical splitting reactions or within externally fired combined cycles. 

Combined-Cycle Power Plant - A power plant that uses two thermodynamic cycles to achieve higher overall system efficiency e.g. the heat from a gas-fired combustion turbine is used to generate steam for heating or to operate a steam turbine to generate additional electricity. 

The functioning of these sprinklers can be initiated by an electronic detection system, or by heat-sensitive valves at each sprinkler head. When a fire is detected, a spray (or more recently, a mist) of water is emitted. The water absorbs the heat of the fire through a phase change to steam and thus arrests the combustion cycle. In certain appHcations where oil fires are expected, such as in restaurant kitchens, a special foam or gel replaces the water in the system. 

Brandvoll, 0. and Holland, O. (2002) Inherent CO2 capture using Chemical Looping Combustion in a Natural Gas Fired Power Cycle, Asme Turbo Expo 2002, Land, Sea Air, Amsterdam, pp. 1-7. 

O2/CO2 combustion in natural gas fired combined cycle with exhaust gas recirculation OJCO2 combustion of coal with exhaust gas recirculation Chemical-looping combustion... 

The application of oxy-combustion to a coal-fired steam cycle is illustrated in Fig. 10.6. Since combustion of coal in pure oxygen produces flame temperatures much higher than combustion in air, a portion of the C02-rich flue gas is typically recirculated back to the burner to limit the peak temperature in the combustion chamber. Different arrangements can be adopted Fig. 10.6 recycles a portion of the dry exhaust from the flue gas desulfurizer (FGD) back to the stream that transports the pulverized coal to the burner. A wet recycle stream, drawn just downstream of the electrostatic precipitator, provides additional inert gas to keep the furnace temperature close to that found in air fired boilers. 

Theoretically, oxy-combustion could also be applied to internal combustion cycles such as natural gas fired combined cycles (NGCC). In these cycles, however, the combustion products also serve as the working fluid, and the switch from air- to oxy-firing dramatically changes the composition of the exhaust, necessitating a complete redesign of the turbomachinery. Because of these significant technical and economic barriers, this approach is not under active development. 

This is driven by the heat of the flame promoting the pyrolysis of the polymer. The process will continue as long as the heat transmitted to the polymer is sufficient to keep its rate of thermal degradation above the level required to feed the flame, otherwise it will extinguish. The self-sustained combustion cycle occurs in both the condensed and gas phase. This means that in order to extinguish the flame by depressing the rate of chemical and/or physical processes taking place in one or both phases, polymers have to contain a variety of additives that may act as fire retardants or they have to be modified (chemical or physical modifications) to resist fire [2]. 

Walter E, Krartz HT, Almhen P. Lignite fired combined cycle heat and power plant using pressurized fluidized bed combustion. Proceedings of the 14th International Conference on Fluidized Bed Combustion, ASME, 1997, pp 359-369. 

Chemical Regeneration. In most MHD system designs the gas exiting the toppiag cycle exhausts either iato a radiant boiler and is used to raise steam, or it exhausts iato a direct-fired air heater and is used to preheat the primary combustion air. An alternative use of the exhaust gas is for chemical regeneration, ia which the exhaust gases are used to process the fuel from its as-received form iato a more beaeftcial oae. Chemical regeaeratioa has beea proposed for use with aatural gas and oil as well as with coal (14) (see Gas, natural Petroleum). 

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