Reactants preheating effect

It was observed that higher temperatures were reached in the reactor on changing the preheating method, the effect being more pronounced at 02 CH4 feed ratios lower than 0.7, due to the minor extent of the oxidation reaction. However, the trend of the temperature profile along the reactor was unchanged irrespective of the means of reactant preheating. 

In conclusion, thermodynamic analysis can provide the optimal operating conditions to achieve the best ATR performance. It has been found that preheating the reactants promotes H2 production. This effect is more pronounced at higher H20 CH4 ratios and at 02 CH4 molar ratios ranging from 0.1 to 0.7. Employing... 

We measured the heat of copolymerization in emulsion for copolymer containing 13.5 mole % styrene at 60°C. Measurements were made with a styrene feed at 20°C therefore, some reaction heat was used to warm the styrene to 60°C. Experiments indicated that this effect was partially compensated for by the heat of mixing because the mixing of styrene with the reactants was very slightly exothermic. If the styrene were preheated to 60°C, the effect would be to raise the measured heat of copolymerization by about 0.09 kcal./ mole. A value of 20.2 kcal/mole (i.e., 337 cal/g) was obtained for the heat of copolymerization. In order to elucidate this unexpectedly high finding, we also measured the heat of homopolymerization of acrylonitrile under similar emulsion conditions in the same apparatus a value of 22.1 kcal/mole was obtained. 

If the reactants are to be preheated, it should be done before mixing, unless a catalyst is necessary for the reaction to take place. Otherwise there is no assurance that the reaction would not begin inside the preheater, where it could not be controlled. Adding heat in the preheater(s) and removing it in the reactor is hardly economical. But once a reaction is initiated, it is often possible to bypass the preheaters without adverse effect. 

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