Fuel production oxidation

The Beckstead-Derr-Price model (Fig. 1) considers both the gas-phase and condensed-phase reactions. It assumes heat release from the condensed phase, an oxidizer flame, a primary diffusion flame between the fuel and oxidizer decomposition products, and a final diffusion flame between the fuel decomposition products and the products of the oxidizer flame. Examination of the physical phenomena reveals an irregular surface on top of the unheated bulk of the propellant that consists of the binder undergoing pyrolysis, decomposing oxidizer particles, and an agglomeration of metallic particles. The oxidizer and fuel decomposition products mix and react exothermically in the three-dimensional zone above the surface for a distance that depends on the propellant composition, its microstmcture, and the ambient pressure and gas velocity. If aluminum is present, additional heat is subsequently produced at a comparatively large distance from the surface. Only small aluminum particles ignite and bum close enough to the surface to influence the propellant bum rate. The temperature of the surface is ca 500 to 1000°C compared to ca 300°C for double-base propellants. 

At still higher temperatures, when sufficient oxygen is present, combustion and "hot" flames are observed the principal products are carbon oxides and water. Key variables that determine the reaction characteristics are fuel-to-oxidant ratio, pressure, reactor configuration and residence time, and the nature of the surface exposed to the reaction 2one. The chemistry of hot flames, which occur in the high temperature region, has been extensively discussed (60-62) (see Col ustion science and technology). 

A solid propellant is a mechanical (heterogeneous) or a chemical (homogeneous, or colloidal) mixture of solid-state fuel and oxidizer-rich chemicals. Specially-formed charges of solid propellant (grains) arc placed in the combustion chamber of the solid rocket motor (SRM) at a production facility. Once assembled, the engine does not require additional maintenance, making it simple, reliable and easy to use. 

One extremely important point to realize is that different propellant types may have different rate-controlling processes. For example, the true double-base propellants are mixed on a molecular scale, since both fuel and oxidizing species occur on the same molecule. The mixing of ingredients and their decomposition products has already occurred and can therefore be neglected in any analysis. On the other hand, composite and composite modified-double-base propellants are not mixed to this degree, and hence mixing processes may be important in the analysis of their combustion behavior. 

The basic approach taken in the analytical studies of composite-propellant combustion represents a modification of the studies of double-base propellants. For composite propellants, it has been assumed that the solid fuel and solid oxidizer decompose at the solid surface to yield gaseous fuel and oxidizing species. These gaseous species then intermix and react in the gas phase to yield the final products of combustion and to establish the flame temperature. Part of the gas-phase heat release is then transferred back to the solid phase to sustain the decomposition processes. The temperature profile is assumed to be similar to the situation associated with double-base combustion, and, in this sense, combustion is identical in the two different types of propellants. 

Figure 20, a magnitude schematic view of zone 1 in Fig. 19, depicts this effect. These exothermic oxidative reactions in zone 1 can release sufficient heat to expel partially combusted products, pyrolysis products, and fuel and oxidizer fragments into the gas phase, where they can intermix and burn completely. The maximum flame temperature will then be reached in the luminous zone, where the largest portion of the heat is released. However, a relatively... 

In this burner configuration, fuel is injected directly into the combustion chamber and hence, one would initially categorize it as a nonpremixed burner. However, the overall combustion process is quite complex and involves features of nonpremixed, partially premixed, and stratified combustion, as well as the possibility that the autoignition of hot mixtures of fuel, air, and recirculated combushon products may play a role in stabilizing the flame. Thus, while one may start from simple concepts of nonpremixed turbulent flames, the inclusion of local exhnchon or flame lift-off quickly increases the physical and computational complexity of flames that begin with nonpremixed streams of fuel and oxidizer. 

For several hours after a meal, while the products of digestion are being absorbed, there is an abundant supply of metabolic fuels. Under these conditions, glucose is the major fuel for oxidation in most tissues this is observed as an increase in the respiratory quotient (the ratio of carbon dioxide produced to oxygen consumed) from about 0.8 in the starved state to near 1 (Table 27-1). 

Enzymes are efficient catalysts for cathodic and anodic reactions relevant to fuel cell electrocatalysis in terms of overpotential, active site activity, and substrate/reaction specificity. This means that design constraints (e.g., fuel containment and anode-cathode separation) are relaxed, and very simple devices that may take up ambient fuel or oxidant from their environment are possible. While operation is generally confined to conditions close to ambient temperature, pressure, and pH, and power densities over about 10 mW cm are rarely achieved, enzyme fuel cells may be particularly useM in niche environments, for example scavenging trace H2 released into air, or sugar and O2 from blood. Thus, trace or unusual fuels become viable for energy production. 

Contrary to traditional fuel cells, biocatalytic fuel cells are in principle very simple in design [1], Fuel cells are usually made of two half-cell electrodes, the anode and cathode, separated by an electrolyte and a membrane that should avoid mixing of the fuel and oxidant at both electrodes, while allowing the diffusion of ions to/from the electrodes. The electrodes and membrane assembly needs to be sealed and mounted in a case from which plumbing allows the fuel and oxidant delivery to the anode and cathode, respectively, and exhaustion of the reaction products. In contrast, the simplicity of the biocatalytic fuel cell design rests on the specificity of the catalyst brought upon by the use of enzymes. 

Flow diagram of the process for hydrogen and distillate fuel production from residual oil using iron oxides and steam. 1 = Cracking reactor, 2 = distillation column, 3 = hydrogen generator, and 4 = hydrodesulfurization reactor. 

The main difference between a fuel cell and a battery is that the fuel and oxidants are not integral parts of the fuel cell, but instead are supplied as needed to provide power to an external load, while the waste products are continuously removed. Where hydrogen is supplied as the fuel to the anode and oxygen to the cathode, this waste product is only water. 

See also Fluidized-bed entries Fluid-bed direct oxidation process, 10 656 Fluid-bed dryers, 9 122-123, 130-131 two-stage, 9 125 Fluid-bed roasters, 16 141 Fluid catalytic cracking (FCC), 11 678-699, 700-734 18 651, 653 20 777 24 257, 271. See also FCC entries Fluidized-bed catalytic cracking (FCC) clean fuels production and, 11 686-689 defined, 11 700... 

Fuel octane number, 72 392, 395 Fuel oil, as a petroleum product, 78 669 Fuel oil additives amine oxides, 2 473 fatty amines, 2 534 Fuel properties, of ethers, 70 574 Fuel sources, chemical industry, 70 136 Fuel spills, hydrazine, 73 588 Fuels production, hydrocracking for, 76 842-844 Fuel sulfur, 70 54... 

A fuel cell is an electrochemical conversion device. It produces electricity from fuel and an oxidant, which react in the presence of an electrolyte. The reactants flow into the cell, and the reaction products flow out of it, while the electrolyte remains within it. Fuel cells are different from electrochemical cell batteries in that they consume reactant, which must be replenished, whereas batteries store electrical energy chemically in a closed system. The chemical energy of the fuel is released in the form of an electrical energy instead of heat when the fuel is oxidized in an ideal electrochemical cell. Energy conversion by a fuel cell depends largely... 

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