Fuel rich combustion

Hall R J and Boedeker L R 1984 CARS thermometry in fuel-rich combustion zones Appl. Opt. 23 1340-6... 

The plant is designed to satisfy NSPS requirements. NO emission control is obtained by fuel-rich combustion in the MHD burner and final oxidation of the gas by secondary combustion in the bottoming heat recovery plant. Sulfur removal from MHD combustion gases is combined with seed recovery and necessary processing of recovered seed before recycling. 

The key elements of the ATR technology are the burner and the catalyst. The burner provides proper mixing of the feed streams, and the fuel-rich combustion is taking place... 

Under fuel-rich combustion conditions, in addition to sulfur dioxide, the stable sulfur products are found to be hydrogen sulfide, carbonyl sulfide, and elemental sulfur. 

Nitramine composite propellants composed of HMX or RDX particles and polymeric materials offer the advantages of low flame temperature and low molecular mass combustion products, as well as reduced infrared emissions. The reduced infrared emissions result from the elimination of COj and H2O from the combustion products. To formulate these composite propellants, crystalline nitramine monopropellants such as HMX or RDX are mixed with a polymeric binder. Since both HMX and RDX are stoichiometrically balanced, the polymeric binder acts as a coolant, producing low-temperature, fuel-rich combustion products. This is in contrast to AP composite propellants, in which the binder surrounding the AP particles acts as a fuel to produce high-temperature combustion products. 

Before we examine the oxidation pathways available to aromatic systems, it is first instructive to review the most notorious role of these compounds in combustion chemistry their propensity to lead to soot formation. Soot is a byproduct of fuel-rich combustion, and soot particles can affect respiration and general health in humans." Soot production is a result of polycyclic aromatic hydrocarbon (PAH) formation in flames as reactive hydrocarbon radical intermediates combine to grow... 

Acetylene can be produced by pyrolysis of coal and by fuel-rich combustion of alkanes, a process that also produces soot or carbon black, the major ingredient in automobile tires. Acetylene can also be made with nearly stoichiometric efiiciency by decomposing calcium carbide, CaC, which is produced by pyrolyzing limestone and coke,... 

CO Carbon monoxide—exhaust emission resulting from incomplete combustion and/or fuel-rich combustion. 

The physical and chemical properties of synthetic crudes are different from those of petroleum. Increased NO and soot production are the principal problems of the combustion of synthetic fuels, and control concepts for these two problems are in conflict. Fuel-rich combustion decreases NO but augments soot production, while fuel-lean combustion decreases (and can eliminate) soot production but augments NO emissions. Moreover, control procedures can affect combustion efficiency and heat-transfer distribution to the chamber surfaces. Table I, taken from Grumer (6), illustrates some specific relevant properties of synthetic liquid fuels and petroleum-based fuels. The principal differences between these fuels as related to their combustion behavior are summarized in Table II. 

A further point is that the equilibrium levels of TFN under fuel-rich combustion conditions are very low. The stable form of nitrogen is N2. In practical combustors, however, equilibrium is not attained because of the slow rates of both chemical and physical (mixing) processes. The chemical processes consist of reactions convering fuel-nitrogen species to N2, the reaction of NO with hydrocarbon species to form HCN, and the subsequent slow conversion of HCN to N2. 

The model combustor used in the present study was a copy of one configuration (Configuration 2C) evaluated under the DOE/NASA Low N0x Heavy Fuel Combustor Concepts Program, and consisted of four component sections fuel preparation, fuel-rich combustion, air quench, and fuel-lean combustion sections (2). All of the test fuel was injected into a rich combustion... 

Thompson D (1994b), Chemosphere 29 2583-2595.. .Thermodynamic considerations in dibenzodioxin and dibenzofuran formation concentrations of chlorinated dioxins and furans in model fuel-rich combustion gases"... 

Consequently, a qualitative difference was observed in chem-ion behavior between fuel-lean and fuel-rich combustion. The ion yield... 

Note that this definition differs slightly from the one commonly used in industry in which the stoichiometry is usually defined as the total oxidizer flow divided by the fuel flow. The problem with the definition commonly used in industry is that the stoichiometry must be recalculated whenever the oxidizer composition changes and that stoichiometric conditions change for each oxidizer composition. This is not a concern if air is always used as the oxidizer, which is the case for the vast majority of combustion processes. The benefit of the definition used here is that stoichiometry is independent of the oxidizer composition, so stoichiometric conditions are the same for any oxidizer composition. In Equation 1.2, S = x/1 = x. Theoretically, for the complete combustion of CH4, S = 2.0. Actual flames generally require some excess 02 for complete combustion of the fuel. This is due to incomplete mixing between the fuel and oxidant. For the fuel rich combustion of CH4, S < 2.0. For the fuel lean combustion of CH4, S > 2.0. 

IMPULSE PRODUCTION BY INJECTING FUEL-RICH COMBUSTION PRODUCTS 331... 

---