Fig. 6. Effect of thermostat temperature (T = 393, 423, 450 ◦ C) on temperature pro- files in tubular reactor at residence time 2.1 s.
that the endothermic process of ethanol dehydration in tubular reactor is characterized by strongly pronounced “cold spot”. The increase in thermostat temperature from 393 to 450 ◦ C leads to the increase in ethanol conversion (see Table 2). It is important to mention that the concentration of ethylene in a dry gas is suffi- ciently high (>98 mol.%) and it practically does not change in all the examined range of thermostat temperatures (390–460 ◦ C). The lowest index of ethanol to raw ethylene consumption C = 1.7 kg/kg was obtained at thermostat temperature 423 ◦ C. With a further increase in thermostat temperature, the index of ethanol/raw ethy- lene consumption increases because of the increase in by-products formation at temperatures higher than 423 ◦ C.
The effect of residence time on temperature profiles in tubular reactor and corresponding process parameters at a constant ther- mostat temperature 423 ◦ C are presented in Fig. 7 and Table 3. Less sensitive cold spot profiles are observed for variation of residence time in comparison with Fig. 6. The ethanol conversion rises with an increase of residence time. At temperature 423 ◦ C, the ethylene concentration in dry gas does not depend on the residence time