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Solid combustion efficiency

In AFBC units, heat is removed from the flue gas by a convection-pass tube bank. The particulates leaving the boiler with the flue gas consist of unreacted and spent sorbent, unburned carbon, and ash. Multiclones after the convection pass remove much of the particulate matter and recvcle it to the combustor, increasing the in-furnace residence time an improving combustion efficiency and sulfur retention performance. Bubbling PFBC units do not have convection-pass tube banks and do not recycle solids to the boiler. [Pg.2387]

A new system theory - the three-step model - of packed-bed combustion is formulated. Some new quantities and efficiencies are deduced in the context of the three-step model, such as the conversion gas, the solid-fuel convertibles, the conversion efficiency and the combustion efficiency. Mathematical models to determine the efficiencies are formulated. [Pg.42]

Some new concepts have been deduced in the context of the three-step model, for example, the conversion system, the conversion gas, the conversion efficiency, and the combustion efficiency. Two new physical quantities have been associated with the conversion gas. The physical quantities are referred to as the mass flow and the stoichiometry of the conversion gas. The conversion efficiency is a measure of how well the conversion system performs, that is, the degree of solid-fuel convertibles that are converted from the conversion system to the combustion system. The combustion efficiency is defined as the degree of carbon atoms being oxidised to carbon dioxide in the combustion system. In other words, the combustion efficiency is a measure of the combustion system performance. [Pg.44]

These results show that droplet vaporization must be different between the three flames. Droplet and fuel vapor transport must be significantly different for these flames and must affect combustion efficiency. The solid-cone nature of the spray flame was found to be preserved irrespective of the atomization gas. [Pg.257]

The fixed-carbon value is one of the values used in determining the efficiency of coal-burning equipment. It is a measure of the solid combustible material that remains after the volatile matter in coal has been removed. For this reason, it is also used as an indication of the yield of coke in a coking process. Fixed carbon plus ash essentially represents the yield of coke. Fixed-carbon values, corrected to a dry, mineral-matter-free basis, are used as parameters in the coal classification system (ASTM D-388). [Pg.60]

FIGURE 15.15 Combustion efficiency (%) of various PC/ABS materials calculated using the THE/ML measured in the cone calorimeter, and the heat release per ML for the complete combustion of the volatiles monitored in the PCFC. Systems that do not show flame inhibition show combustion efficiencies of around 1, according to the well-ventilated fire scenario of the cone calorimeter. Systems, in which adding aryl phosphates result in flame inhibition, show combustion efficiencies of around 0.8. When the release of phosphorus is reduced by competing reactions in the solid state, combustion efficiencies of between 0.8 and 1 are observed. [Pg.407]

Say, for example, it is not possible to suspend the necessary amount of particles in a thixotropic system, or that similarly in the hybrid it was not possible to burn the metal efficiently because the large quantities of metal particles must be projected into the flame from a decomposing surface creating only a small amount of gaseous components. Then it is possible to place small quantities of metal in both the liquid and solid to obtain higher combustion efficiency and thus performance. Figure IV.B. 1. represents this approach as the gelled hybrid (F). [Pg.108]

Figures 4, 5, and 6 show the solid conversion efficiencies of the three SRC and the reference coals in air in the DTFS at three temperatures (furnace wall temperatures of 2500, 2700, and 2800 F). The CSD and PFD SRC and WSB reference coal achieved a high solid conversion efficiency (>75%) in less than 50 milliseconds, while the ASD SRC and the KHB reference coal resulted in lower initial conversion efficiencies, less than 60%. The initial high degree of conversion of the CSD and PFD SRC results in relatively low amounts of residual char to be burned in the latter stages of combustion. Figures 4, 5, and 6 show the solid conversion efficiencies of the three SRC and the reference coals in air in the DTFS at three temperatures (furnace wall temperatures of 2500, 2700, and 2800 F). The CSD and PFD SRC and WSB reference coal achieved a high solid conversion efficiency (>75%) in less than 50 milliseconds, while the ASD SRC and the KHB reference coal resulted in lower initial conversion efficiencies, less than 60%. The initial high degree of conversion of the CSD and PFD SRC results in relatively low amounts of residual char to be burned in the latter stages of combustion.
In order to extrapolate the laboratory results to the field and to make semiquantitative predictions, an in-house computer model was used. Chemical reaction rate constants were derived by matching the data from the Controlled Mixing History Furnace to the model predictions. The devolatilization phase was not modeled since volatile matter release and subsequent combustion occurs very rapidly and would not significantly impact the accuracy of the mathematical model predictions. The "overall" solid conversion efficiency at a given residence time was obtained by adding both the simulated char combustion efficiency and the average pyrolysis efficiency (found in the primary stage of the CMHF). [Pg.218]

From an overall combustion efficiency standpoint, both the CSD and PFD SRC are relatively reactive solid fuels comparable in reactivity to subbituminous coal. The ASD SRC is relatively un-reactive in comparison. [Pg.222]

O Ferrocene is the common name given to a unique compound that consists of one iron atom sandwiched between two rings containing hydrogen and carbon. This orange, crystalline solid is added to fuel oil to improve combustion efficiency and eliminate smoke. As well, it is used as an industrial catalyst and a high-temperature lubricant. [Pg.214]

Based on the experience of these 75 t/h boilers, a 220 t/h CFBC boiler has been designed and is now being fabricated. A two-stage channel separator, as shown in Fig. 39, is used on these CFBC boilers. This is followed by multi-cyclones. By using this combination of gas-solid separators, and with fly ash reburn, the combustion efficiency has reached 97.5% for a 12,000-kJ/kg low-grade coal. [Pg.374]

Some concerns direcfly related to atomizer operation include inadequate mixing of liquid and gas, incomplete droplet evaporation, hydrodynamic iastabiUty, formation of nonuniform sprays, uneven deposition of liquid particles on solid surfaces, and drifting of small droplets. Other possible problems include difficulty in achieving ignition, poor combustion efficiency, and incorrect rates of evaporation, chemical reaction, solidification, or deposition. Atomizers must also provide the desired spray angle and pattern, penetration, concentration, and particle size distribution. In certain appHcations, they must handle high viscosity or non-Newtonian fluids, or provide extremely fine sprays for rapid cooling. [Pg.334]

It should be mentioned that the combustion technology is not limited to these major designs. In catalytic fluidized bed combustion of low-sulfur natural gas, for example, powder catalysts are operated in the turbulent flow regime where the gas-solid contact is optimal so as to maintain a high combustion efficiency [46]. [Pg.885]

Combustion efficiency is a characterization of the combustion systems ability to burn fuel. Burners producing a low level of unburned fuel while operating at low excess air levels are considered efficient. Combustion efficiency is different for various fuels and, generally, gaseous and liquid fuels burn more efficiently than solid fuels. [Pg.395]


See other pages where Solid combustion efficiency is mentioned: [Pg.943]    [Pg.216]    [Pg.495]    [Pg.29]    [Pg.39]    [Pg.85]    [Pg.3]    [Pg.409]    [Pg.104]    [Pg.322]    [Pg.205]    [Pg.213]    [Pg.1513]    [Pg.68]    [Pg.358]    [Pg.359]    [Pg.2141]    [Pg.70]    [Pg.435]    [Pg.944]    [Pg.192]    [Pg.29]    [Pg.39]    [Pg.2644]    [Pg.2654]    [Pg.97]    [Pg.225]    [Pg.2623]    [Pg.2633]    [Pg.2390]   
See also in sourсe #XX -- [ Pg.80 , Pg.81 ]




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