Hydrocarbon partial pressure, reduction

Advanced Cracking Reactor. The selectivity to olefins is increased by reducing the residence time. This requires high temperature or reduction of the hydrocarbon partial pressure. An advanced cracking reactor (ACR) was developed jointly by Union Carbide with Kureha Chemical Industry and Chiyoda Chemical Constmction Co. (72). A schematic of this reactor is shown in Figure 6. The key to this process is high temperature, short residence time, and low hydrocarbon partial pressure. Superheated steam is used as the heat carrier to provide the heat of reaction. The burning of fuel... 

In general, with decreasing hydrocarbon partial pressure, unsaturated components such as acetylene, ethylene, propylene, and butadiene increase whereas BTX, pyrolysis fuel oil, and saturated components such as methane, ethane, and propane decrease. Low hydrocarbon partial pressure can be attained either by high steam dilution or by low absolute pressure in the cracking coil, which is determined by furnace outlet pressure and pressure drop in the cracking coil. For each specific case there is an optimum steam dilution. Reduction of steam dilution influences yields, utilities, running times and, in the case of a new ethylene plant, of course, investment costs—but in different ways, either positive or negative. Thus, an optimization has to be carried out to identify the most economic steam dilution. 

Explosion Hazard of Organic Vapors, Reduction of. A process which comprises the treatment of wood with. hydrocarbon vapors at an elevated temp, after which compressed air is used to impregnate the wood with a preservative. Expln hazards are reduced by introducing steam at 10—20psi before applying the air. Steam is added in an amt equal to the partial pressure of die organic vapor in the closed space... 

As in the cobalt system, the reaction generates significant quantities of CH4 as a by-product (in some cases, the methane is the major product). The selectivity of homologated alcohol to hydrocarbon appears to be independent of the partial pressures of either CO or H2 127), and the authors suggest that this could be attributable, at least in the Mn system, to the relative rates of methyl migration to homolytic bond dissociation. In the iron system, methane is generated by simple reductive elimination from the HFe(CH3)(CO)4 intermediate. 

High copper loadings favor the formation of bulk oxides on this surface. At the same time with high copper contents the introduction of oxygen induces a decrease in the reduction of NO into nitrogen by propane. The presence of bulk copper oxides leads to the formation of a catalyst very active for the oxidation of the hydrocarbon molecule by oxygen. Because of the decrease in the reductant partial pressure NO cannot be converted into nitrogen. 

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