application of threshold model with various tube wall temperatures for crude oil preheat train fouling

the propose of this paper is to introduce a new model for crude oil fouling in preheat trains of crude distillation unit. the experimental results of australian light crude oil with the tube side surface temperatures between 200-260 oc and fluid velocity ranged 0.25 to 0.4m/s were used. the activation energy of chemical reaction depends on the surface temperature has been calculated.  the model includes two parts. in the first part it deals with a term for fouling formation and the second part with a term for fouling removal due to chemical and tube wall shear stress respectively. by using the proposed model for australian crude oil based on saleh et.al.data the fouling formation rate has been calculated and the threshold curves to identify fouling and no fouling formation zones have been drawn. finally, a model was developed for various temperatures and shows better results in relation to available models.