Other Organic Fuels

The number of possible organic fuels is enormous. Considerations in selecting a candidate include  

Extent of oxidation This will be a primary factor in the heat output per gram of the fuel. 

Boiling point/volatility If the fuel readily vaporizes or sublimes, the storage life of the mixture will be brief unless precautions are taken in packaging to prevent loss of the material. 

Chemical stability An ideal fuel should be available commercially in a high state of purity, and should maintain that high purity during storage. Materials that are easily air oxidized, such as aldehydes, are usually poor 

Solubility Organic fuels frequently double as binders, and some solnbility in water, acetone, or alcohol is required to obtain good binding behavior. 

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For a good spark effect, the fuel must contain particles large enough to escape from the flame prior to complete combustion. Also, the oxidizer must not be too effective, or complete reaction will occur in the flame. Charcoal sparks are difficult to achieve with the hotter oxidizers potassium nitrate (KNO 3) -with its low flame temperatures - works best. Some gas production is required to achieve a good spark effect by assisting in the ejection of particles from the flame. Charcoi, other organic fuels and binders, and the nitrate ion can provide gas for this purpose. 

To go further, particularly with higher weight alcohols like glycerol or other organic fuels (glucose, saccharose,. ..) we have to combine most of the physical chemical and analytical techniques, available today, and preferably working in situ. 

DMFCs have potential near-term applications mainly in the portable power source market, as they are smaller, lighter, simpler, and cleaner than conventional batteries. Liquid methanol is consumed directly in a DMFC, which implies a higher energy density of the fuel cell system. But the power densities achievable with state-of-the-art DMFCs are still very small in comparison to hydrogen-fuelled PEMFCs. One of the major problems lies in the use of liquid methanol solution on the anode of the DMFC, which, on the one hand, keeps the ionomeric membrane water saturated (and thus no humidification is needed) but, on the other hand, does not keep fuel (methanol or any other organic fuel, e.g., formic acid, ethanol) and water from permeating to the cathode side, since the basic PFSA membranes are permeable to both methanol and water. - The fuel and water crossover from anode to cathode hampers the performance of the air cathode. 

Finally, combustion calculations regarding common hydrocarbons and other organic fuels require accurate experimental data. Therefore, the usual data required for these computations are reported in Table 17.3. 

Contaminants/impurities at the anode are mainly brought in by the fuel feed stream. Impurities in the hydrogen fuel, such as CO, H2S, NHj, organic sulfur-carbon, as well as carbon-hydrogen compounds, are primarily from the manufacturing process, in which natural gas or other organic fuels are reformed to produce hydrogen. In this section, several major anode contaminants, such as CO H2S, and NH3, will be discussed. 

In the standard method, the metal enclosure (called the air chamber) used to hold the hydrocarbon vapors is immersed in water before the test, then drained but not dried. This mode of operation, often designated as the wet bomb" is stipulated for all materials that are exclusively petroleum. But if the fuels contain alcohols or other organic products soluble in water, the apparatus must be dried in order that the vapors are not absorbed by the water on the walls. This technique is called the dry bomb" it results in RVP values higher by about 100 mbar for some oxygenated motor fuels. When examining the numerical results, it is thus important to know the technique employed. In any case, the dry bomb method is preferred. 

AH other organic waste-process and vent streams are burned in a dare, in an incinerator, or in a furnace where fuel value is recovered. Wastewater streams are handled in the plant biological treatment area. 

Incineration. Gases sufftciendy concentrated to support combustion are burned in waste-heat boilers, dares, or used for fuel. Typical pollutants treated by incineration are hydrocarbons, other organic solvents and blowdown gases, H2S, HCN, CO, H2, NH, and mercaptans. VOC... 

Segregate stocks of chlorine from acetylene, hydrogen, ammonia and fuel gases and ensure no accidental contact with ethers, hydrocarbons and other organics and finely divided metals. Never mix chlorine with another gas in the cylinder. 

The commonest alcohol (see Alcohols) and therefore often called simply alcohol . It is used as a solvent, as a fuel and in the manufacture of many other organic compounds. 

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