Tubular reactor design—II A modified one dimensional model

• Published in: Chemical engineering science 1980, Vol.35 (4), p.897-904
• Main Authors: Ahmed, M., Fahien, R.W.
• Format: Article
• Language: English
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/0009-2509(80)85077-9

A modified one-dimensional model (MODM) is developed for tubular packed reactors with exothermic reactions. The radial temperature and conversion profiles are represented by equations whose parameters are functions of axial position. The parameters depend upon the centerline temperature and conversion, the mean temperature and conversion, and the conversion at the reactor wall. These five variables are represented in terms of five ordinary differential equations which are solved simultaneously. The heat loss to the surroundings is determined from the temperature gradient and the thermal conductivity at the pipe wall. The heat generation due to reaction is obtained from a cross-sectional average reaction rate. The model is used to simulate the oxidation of sulfur dioxide and the oxidation of naphthalene to phthalicanhydride. Although the MODM requires about half the computer time required for the two-dimensional model, it was nevertheless found to yield results of comparable accuracy for both the systems. The average values of conversion and temperature from the new model are also shown to be more accurate than those obtained with the conventional one-dimensional model (CODM). Furthermore the new model also accurately predicts the heat loss at the wall and provides information on the hot spot temperature and location whereas the CODM does not.