Additives combustion improvers

US Navy Smoke Abatement Additive Combustion Improver No 2 (Cl-2). COMNAVAIR-PACNOTE 470, NAVAIRPAC 742, Sec 1, P2... 

Additives for Improving Combustion and for Reducing Smoke and Soot Emissions... 

Because there seldom is only one specific problem associated with the fuel being used, most fuel treatments are blends of active agents, such as combustion improvers and slag modifiers. In addition, fireside problems tend to be interrelated, so that, for example, inefficient fuel combustion leads to heavy sooting in the combustion area and dry smutting from the exit gases. 

NOTE Where smoke suppression is required (e.g., in a boiler fired on poor-quality heavy fuel oil) and a typical liquid combustion improver product is employed, to achieve a 35% reduction in unbumed particles may require the addition of 2/3 pint of additive per 2,500 gallons of fuel (approximately 0.33 liters per 10m3). Doubling the smoke particle reduction to 65%, however, may require triple the feed rate of the additive. 

In aircraft jet fuels, for example, especially those for aircraft of the supersonic type, the chief problem so far encountered has been thermal stability prior to combustion. The fuel must be used as a cooling agent, and the resultant exposure to heat accelerates the formation of gum and sediment. These cause plugging of filters and fuel nozzles, and lacquering of heat-exchanger surfaces. Research to date has indicated that some additives are effective in improving jet-fuel stability (52), especially if the fuel has first been rigorously refined, but these additives are not combustion improvers in the sense discussed in this paper. 

Ge Tetraethyl lead has been widely used as a gasoline additive to improve combustion but is being phased out because of the toxic hazard associated with all lead compounds. 

The mechanism of action for diesel fuels is not well characterized due to the complexity of its petroleum hydrocarbon mixture. The presence of additives that improve fuel combustion or prevent microbial growth may contribute to toxicity. Based on research conducted with individual components of diesel fuels, the primary mechanism of action for central nervous system (CNS) depression from diesel fuel is the reversible, physical interaction of the aromatic and aliphatic hydrocarbons with cell membranes. Renal toxicity is possibly attributed to oxidative metabolites of some of the aromatic constituents. Eye and skin injury are attributable to direct irritant action and the high lipid solubility that may dissolve protective skin oils and allow penetration into the skin tissue. The dermal carcinogenesis observed in rodents subjected to chronic dermal exposure to diesel may be attributed to the genotoxic activity of PAHs and the promoting activity of repeated dermal injury. 

Unleaded gasolines, in use today, comprise higher concentrations of BTEX compounds (Fig. 6.3) and branched chain hydrocarbons. Oxygenated additives such as methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), methanol and ethanol are also used as antiknock and combustion improvers. 

Reductions in corrosion and deposit formation in oil fired equipment have been achieved with these chemicals in addition to improved combustion. The availability includes powders, water solutions and organo-metallic compounds. 

Gas turbine inlet air cooling to increase density of air to improve the overall efficiency of the combustion cycle as manifested by improvement in the heat rate. It is also noteworthy that eooling will serve to pre-filter and reduce velocity and hence the pressure drop across the inlet air filters providing additional performance improvement. 

Other recent developments include the incorporation of a fire retardant, which retards the combustion of the solvent, and a new additive to improve the wetting of the separator. It is difficult to use these additives in the gel-type electrolytes employed in lithium-ion polymer cells. This may be one reason for the lower market share experienced by lithium-ion polymer cells. 

Oii Additives. Long-chain polymethacrylates increase the viscosity of oil as temperature increases and are therefore used as additives to improve the performance of lubricating oils and hydraulic fluids in internal combustion engines... 

Imtenan, S., Masjuki, H.H., et al, 2015. Evaluation of n-butanol as an oxygenated additive to improve combustion-emission-performance characteristics of a diesel engine fuelled with a dhesel-Calophyllum inophyllum biodiesel blend. RSC Advances 5 (22), 17160—17170. 

Improving the cetane number by additives results in better engine behavior, as would be predicted by the combustion mechanisms in the diesel engine (noise reduction, better operating characteristics, particularly when cold). Nevertheless, concerning certain items such as pollution emissions, it may be better to obtain a higher cetane number rather by modification of the... 

Diesel fuels, like gasoline, are formulated with additives that affect the process of combustion, in this case to improve the cetane number. Diesel fuels also contain detergents for irijection systems as well as compounds for improving the fuel s low tempierature rheology. Finally, decreasing particulate emissions is a problem of increasing concern, but the mechanism of action to promote this effect is not clearly understood. 

Unlike spark-induced combustion engines requiring fuel that resists autoignition, diesel engines require motor fuels, for vhich the reference compound is cetane, that are capable of auto-igniting easily. Additives improving the cetane number will promote the oxidation of paraffins. The only compound used is ethyl-2-hexyl nitrate. 

Flammability. The results of small-scale laboratory tests of plastic foams have been recognized as not predictive of their tme behavior in other fire situations (205). Work aimed at developing tests to evaluate the performance of plastic foams in actual fire situations continues. All plastic foams are combustible, some burning more readily than others when exposed to fire. Some additives (131,135), when added in small quantities to the polymer, markedly improve the behavior of the foam in the presence of small fire sources. Plastic foams must be used properly following the manufacturers recommendations and any appHcable regulations. 

Some beehive ovens, having various improvements and additions of waste heat boilers, thereby allowing heat recovery from the combustion products, may stiU be in operation. Generally, however, the beehive oven has been replaced by waH-heated, horizontal chamber, ie, slot, ovens in which higher temperatures can be achieved as well as a better control over the quality of the coke. Modem slot-type coke ovens are approximately 15 m long, approximately 6 m high, and the width is chosen to suit the carbonization behavior of the coal to be processed. For example, the most common widths are ca 0.5 m, but some ovens may be as narrow as 0.3 m, or as wide as 0.6 m. 

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