Hydrocarbon fuels, chemical availability

The catalytic activation of carbon monoxide is a research area currently receiving major attention from academic, industrial, and government laboratories. There has been a long standing interest in this area however, the new attention obviously is stimulated by concerns with the present and future costs and availability of petroleum as a feedstock for the production of hydrocarbon fuels and of organic chemicals. One logical alternative source to be considered is synthesis gas, mixtures of carbon monoxide and hydrogen that can be produced from coal and other carbonaceous materials. 

Some partial contributions to the total availability are then considered. Thus, a simple expression for the pressure availability of an incompressible fluid is developed. Formulae for the chemical availability of hydrocarbon fuels obtained by Szargut and Styrylska are then discussed and summarized in a separate table. Equations for the average value of the specific heat of various solid fuels between some fixed temperature and some other variable one are also given, as is a technique to estimate the lower heating value of a fuel of known atomic composition. Finally, a simplified approach used in approximating the thermal availability of tars is described. 

Table II. Chemical Availability of Hydrocarbon Fuels (based on Szargut and Styrylska s work)...

A basic requirement of burner combusting liquid fuels is a high-quality fuel atomization [9], necessary for complete evaporation and burnout in the area of the flame. If some fuel drops are not evaporated and combusted in the area of flame, concentrations of carbon monoxide and unburned hydrocarbons (UHCs) in flue gas increase rapidly. For the above mentioned reason most liquid fuel burners are designed as diffusion burners with fuel atomized in the combustion chamber. The fuel atomization system itself is rather dependent on physical and chemical properties of fuel and availability of auxiliary atomizing medium. Thus there are three basic types of atomization [10] (i.e., pressure, pneumatic, and rotary atomization). Besides these, there are other, less frequent types of atomization using vibrational, acoustic, ultrasonic, and electrostatic atomizers or flash liquid atomization. 

In cases where the polyethylene alone cannot be made to resist certain chemicals, such as hydrocarbon fuels, other materials can be extruded over the outer polyethylene jacket for an additional measure of protection for exposed cable. In these cases the added materials themselves may not be ideally suited for use as a stand-alone cable jacket due to certain material properties, cost, or other considerations. However, when extruded over a base polyethylene outer jacket the overall sheath combination results in composite structure that is resistant to a wide range of operating conditions and environmental concerns. Oversheaths consisting of nylon are available from some manufacturers and can be useful in heavy industrial environments where exposure to known aggressive chemicals is likely. Nylon also has been shown to improve the sheath s resistance to boring insects. 

John M. Vohs is the Carl V.S. Patterson Professor and chair of the Department of Chemical and Biomolecular Engineering at the University of Pennsylvania. He joined the faculty there after receiving a B.S. degree from the University of Illinois and a Ph.D. from the University of Delaware. Dr. Vohs research interest is in the field of surface and interfacial science, particularly the relationships between the local atomic structure of surfaces and their chemical reactivity. His work on structure-activity relationships for metal-oxide catalysts, especially those used for selective oxidation reactions and automotive emissions control systems, is widely known. In recent years, he has collaborated in the development of solid-oxide fuel cells that run on readily available hydrocarbon fuels, such as natural gas and diesel. Dr. Vohs has received numerous honors, including an NSF Presidential Young Investigator Award and two Union Carbide Research Innovation Awards, vohs seas.upenn.edu)... 

To put the volume of C4 s used in chemical manufacture in perspective with the amount used for fuel, one finds that approximately 6 percent of the butanes and about 11 percent of the butylenes were used as chemical raw materials. The trends that affect availability of C4 hydrocarbons for chemical and energy end uses are determined by the natural gas processors, petroleum refiners, and, to a growing extent, ethylene manufacture. 

Use of Isotopic Effects in the Determination of Electro-Organic Reaction Mechanisms. Much work has been carried out on the mechanism by which hydrocarbons can be clectrochemically oxidized. Were that easy, it might be possible to use available oil in electrochemical devices (fuel cells) to convert chemical to electrical energy 2—3 times more efficiently than do heat engines (Chapter 13). 

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