The discrepancy between pseudo-homogeneous one-dimensional model and peeudo-homogeneous two-dimensional model is studied. It is found that there are great differences between two models. This paper compares the maxim...The discrepancy between pseudo-homogeneous one-dimensional model and peeudo-homogeneous two-dimensional model is studied. It is found that there are great differences between two models. This paper compares the maximum and minimum values of the radial temperature in the hot spot in came that a single exothermic reaction is carried out, a correlation is obtlioed with peeudo-homogeneous one-dimensional model to describe the entire reactor behavier. A new runaway criterion, based on the occurrence of inflection in the hot spot locus, is developed for the case of pseudo-homogeneous two-dimensional model. This criterion predicts the maximum allowable temperature for safe operation and the regions of runaway, respectively. The calculated results show that, compared with the results based on pseudo-homogeneous one-dimensional model, runaway will easily occur when the radial temperature gradient has to be considered.展开更多
1 INTRODUCTIONWhen an exothermic reaction is carried out in a fixed bed reactor,there exists an axialtemperature profile exhibiting a maximum,known as the hot spot.In certain regions ofthe parametric sensitivity,the h...1 INTRODUCTIONWhen an exothermic reaction is carried out in a fixed bed reactor,there exists an axialtemperature profile exhibiting a maximum,known as the hot spot.In certain regions ofthe parametric sensitivity,the hot spot temperature undergoes very large increases forsmall changes in one or more inlet parameters,and this phenomenon is called runawayand the corresponding inlet condition is known as the critical.The reactor will be outof controlled beyond this condition and brings about a bad influence on process con-展开更多
基金Supported by the Tianjin Natural Science Foundation.
文摘The discrepancy between pseudo-homogeneous one-dimensional model and peeudo-homogeneous two-dimensional model is studied. It is found that there are great differences between two models. This paper compares the maximum and minimum values of the radial temperature in the hot spot in came that a single exothermic reaction is carried out, a correlation is obtlioed with peeudo-homogeneous one-dimensional model to describe the entire reactor behavier. A new runaway criterion, based on the occurrence of inflection in the hot spot locus, is developed for the case of pseudo-homogeneous two-dimensional model. This criterion predicts the maximum allowable temperature for safe operation and the regions of runaway, respectively. The calculated results show that, compared with the results based on pseudo-homogeneous one-dimensional model, runaway will easily occur when the radial temperature gradient has to be considered.
文摘1 INTRODUCTIONWhen an exothermic reaction is carried out in a fixed bed reactor,there exists an axialtemperature profile exhibiting a maximum,known as the hot spot.In certain regions ofthe parametric sensitivity,the hot spot temperature undergoes very large increases forsmall changes in one or more inlet parameters,and this phenomenon is called runawayand the corresponding inlet condition is known as the critical.The reactor will be outof controlled beyond this condition and brings about a bad influence on process con-