Smoke-free combustion

It is interesting to note at this point that polynitrogen compounds are not only of great interest as explosives, but also as rocket propellants. For example, a specific impulse of 408 s and a combustion chamber temperature of 7500 I< have been predicted for N4 (rd) (and for N8 an 7sp of 500 s). From experience, since an increase in the specific impulse of 20 s results in a doubling of the payload, this would be a massive improvement. Furthermore, since polynitrogen compounds exhibit smoke-free combustion, they are also of big interest for tactical rockets. 

Ferrocene has found two interesting applications related to fuel. It is known to promote the smoke-free combustion of fuel. It also prevents knocking in the engine when used as an additive to a fuel. Ferrocene and... 

Fires. Combustion of any kind produces toxic particulate matter, smoke. The combustion can be natural such as a lightning-induced forest fire or unnatural such as the burning of fossil fuel for energy production, a petroleum refinery or plastics warehouse fire)22-23 In addition to particulates, fires produce PAHs, carbon monoxide, organic and inorganic cyanides, and free radicals that are toxicJ24-25 ... 

A lot of work has been done for the synthesis of azido nitroamino compounds, their properties and applications [32]. Reed and Dolah first started the study of this kind of compounds. Rosher, Morton, and Eimslic synthesized series of azido nitroamino compounds, and applied them as the composition of propellants. They notably rise the combustion/buming rate and specific impulse without influencing the pressure index. Their energy approximately equals that of HMX. Their detonation sensitivity is relatively low. They are widely applied in smoke-free propellants with low sensitivity to replace HMX. 

QUESTIOISI What causes a cool fire to be smoky and a hot one to be smoke free Can you give a molecular reason for the smoke Hint If the temperature is too low, combustion will be incomplete. 

Proper fuel atomization to ensxue complete combustion and smoke-free stack over the entire operating range of the gas turbine... 

The products manufactured are predominantiy paraffinic, free from sulfur, nitrogen, and other impurities, and have excellent combustion properties. The very high cetane number and smoke point indicate clean-burning hydrocarbon Hquids having reduced harmful exhaust emissions. SMDS has also been proposed to produce chemical intermediates, paraffinic solvents, and extra high viscosity index (XHVI) lubeoils (see Lubrication and lubricants) (44). 

Soot. Emitted smoke from clean (ash-free) fuels consists of unoxidized and aggregated particles of soot, sometimes referred to as carbon though it is actually a hydrocarbon. Typically, the particles are of submicrometer size and are initially formed by pyrolysis or partial oxidation of hydrocarbons in very rich but hot regions of hydrocarbon flames conditions that cause smoke will usually also tend to produce unbumed hydrocarbons with thek potential contribution to smog formation. Both maybe objectionable, though for different reasons, at concentrations equivalent to only 0.01—0.1% of the initial fuel. Although thek effect on combustion efficiency would be negligible at these levels, it is nevertheless important to reduce such emissions. 

In ideal combustion 0.45 kgs (1 lb.) of air combines with 1.8 kgs (4 lbs.) of oxygen to produce 1.2 kgs (2.75 lbs.) of carbon dioxide and 1.02 kgs (2.25 lbs.) of water vapor. Carbon monoxide, carbon dioxide, nitrogen and water vapor are the typical exhaust gases of ordinary combustion processes. If other materials are present they will also contribute to the exhaust gases forming other compounds, which in some cases can be highly toxic. Imperfect combustion will occur during accidental fires and explosion incidents. This mainly due to turbulence, lack of adequate oxidizer supplies and other factors that produce free carbon (i.e., smoke) particles, carbon monoxide, etc. 

For coloured smoke puffs, pigments based on metal chromates are utilised, the pigment being intimately mixed with a fuel such as magnesium. On combustion in free air, a smoke cloud is produced that has residual colour due to the chromate. 

As demonstrated, two aromatic carbon atoms must be burned to yield enough hydrogen to produce one water molecule. This process yields two carbon atoms which must be oxidized to either CO or C02. Without excess oxygen, free carbon-carbon reactions can result to produce amorphous soot and smoke. By increasing the amount of oxygen delivered into the fuel combustion process, the complete oxidation of all aromatic carbon to either CO or C02 is possible. 

There has been a great recent market demand for halogen-free fire-retardant polymers. Zinc borates are also multifunctional fire retardants in halogen-free polymers. They can promote char formation, reduce the Rate of Heat Release, smoke evolution, carbon monoxide generation, and afterglow combustion. When used in conjunction with metal hydroxides, they can also display synergy in fire test performance. 

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