TEMPERATURE CONTROL OF EXOTHERMIC REACTIONS

A selective hydrogenation process wherein at least two catalyst beds in series is controlled by predicting the inlet temperature to the first catalyst bed in the series required to maintain the concentration of the component being selectively hydrogenated in the effluent flowing from the second reactor within a desired concentration limit. This prediction is biased by a comparison of the actual concentration to the concentration limit. The thus biased prediction is utilized to manipulate the inlet temperature to the first reactor in the series. The inlet temperature to the second reactor to the series is controlled by establishing a prediction of the differential temperature across the second reactor in the series. The predicted differential temperature is compared to the actual differential temperature and the results of the comparison is utilized to control the inlet temperature to the second reactor in the series so as to maintain a desired relationship between the amount of the impurity selectively hydrogenated in the first catalyst bed and the amount of the impurity selectively hydrogenated in the second catalyst bed.