Combustors combustion terms

For attaining higher combustion efficiencies with shorter tailpipes, a provision should be made for several flame holders in the combustion chamber. The optimum arrangement of the flame holders in the combustor in terms of the combustion efficiency, flame stability, and pressure loss should be found. The methodology suggested in sections 12.2 and 12.3 helps to solve this problem. 

The aerodynamic valves have a specially designed inlet (e.g., a profiled orifice in the inlet pipe, contoured diffuser, or a shrouding duct) in which the fluid flow characteristics act as a physical barrier (fluid diode) to the backflow of combustion products. Such pulse combustors are termed the valveless combustors. Example of valveless pulse combustor is shown in Figure 23.4 (Putnam et al., 1986). 

Fuel-rich propellants (FRPs) with high metal content find use in ram-rockets which operate with the combustion of fuel-rich hot gases generated in the primary chamber or combustor and ram air inducted from atmosphere to a secondary chamber or combustor for full combustion. The rocket system where energy for propulsion is derived in such a manner is termed an integrated rocket-ramjet (IRR). The major benefit of a ram-rocket is substantial reduction in the weight of rocket or missile as the oxidizer need not be carried along with the propellant fuel. Fuel-rich propellant formulations for ram-rockets consist of metal fuels, binder... 

Catalytic combustion for gas turbines has received much attention in recent years in view of its unique capability of simultaneous control of NOX) CO, and unbumed hydrocarbon emissions.1 One of the major challenges to be faced in the development of industrial devices is associated with the severe requirements on catalytic materials posed by extreme operating conditions of gas turbine combustors. The catalytic combustor has to ignite the mixture of fuel (typically natural gas) and air at low temperature, preferably at the compressor outlet temperature (about 350 °C), guarantee complete combustion in few milliseconds, and withstand strong thermal stresses arising from long-term operation at temperatures above 1000°C and rapid temperature transients. 

The fundamentals of combustion systems are yielding to treatment at the present time, but interrelationships of their effects in a real combustor require much additional study, particularly in regard to combustion efficiency. Full-scale engine performance has not been explained in terms of fuel vaporization effects (44), and a survey of vaporization literature cannot be applied to a real combustor as the sole criterion for performance... 

Several investigators have suggested that chemical-reaction kinetics control the performance of both ramjet and turbojet combustors (4, 96, 139). Second-order reaction equations were assumed to be the over-all rate determining step, and the influence of combustor inlet-air pressure, temperature, and velocity on combustion efficiency could be explained in terms of their effects on these second-order reactions. Combustion efficiency has been shown to vary inversely with a reaction-rate parameter of the form... 

Specifically, the work done at Plant Sweatt examined the applicability of 1x liquid synthetic fuels to a full scale, wall fired utility boiler 1n terms of boiler efficiency and emission characteristics. EPRI sponsored testing with synthetic fuels at other sites Included small scale combustors, a Combustion Engineering wall-fired utility boiler, a Combustion Engineering tangentially-f1red utility boiler, a combustion turbine and diesel piston engines with generally favorable results. 

PCDD/F formation in combustors is a side-reaction which, in terms of percentage yield, is inconsequential relative to the dominant oxidative reactions between organic matter and chlorine in MSW and oxygen in combustion air. Literature sources indicate that the quantity of HC1 in process gases is at best a secondary determinant in influencing PCDD/F yields, and is much less important than the temperature-time window.27,28... 

In the theoretical studies, a stoichiometric model was employed to describe the overall combustion process and to examine the effects of the biomass composition on a fuel s combustion behaviour in term of flue gas composition, heat output and combustion temperature under ideal conditions. Incorporation with the correlations derived from the experimental work allows prediction of heat efficiency likely to be realised in a real combustion situation for stoker combustors. Good agreement between predicted and empirical results gives confidence in applying the technique to evaluate combustion performance of various biomass fuels without have to undertake combustion trials. 

As part of the experimental phase of the program, Esso Research and Engineering (2i) is conducting combustion studies under a variety of conditions. The initial work (23) utilized a modification of the Longwell-Weiss reactor (24), termed a jet-stirred combustor (Figure 3). This... 

Afterburning is the most common term used to describe the combustion process employed to control gaseous emissions. The term afterburner is appropriate only to describe a thermal oxidizer used to control gases coming from a process where combustion was not complete. Incinerators are used to combust solid, liquid, and gaseous materials when used in this handbook, the term incinerator will refer to combustion of waste streams. Other terms used to describe combustion equipment include oxidizer, reactor, chemical reactor, combustor, etc. 

MW of power. Utilization of DME for power generation offers tremendous environmental benefits, in terms of CO SO and NO emissions. It burns in conventional gas turbines without modifications to the turbine or the combustors. Emissions produced by combustion of conventional fuels in gas turbines include nitrogen oxides, carbon monoxide, unburned hydrocarbons, and sulfur oxides. Dimethyl ether produces no sulfur oxide emission, as the fuel is sulfur free. It generates the least amount of NO CO, and unburned hydrocarbons as compared with natural gas and distillate, and lower CO2 emissions than the distillates. 

After the fuel valve moves from one position to another the flow rate of the fuel delivered to the combustors changes, but a delay due to the inertia of the fuel occms. The fuel enters the combustor and bums along its length at a finite burning rate. Completion of the combustion takes time and adds a further delay to the energy conversion process. A finite time is required for the burnt gas to pass through the power turbine and transfer part of its energy to the turbine. The turbine lead-lag block approximates these conversion processes. The number of lead and lag terms varies from one gas turbine type to another. 

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