Application of sectionalized single-step reaction approach (SSRA) and distributed activation energy model (DAEM) on the pyrolysis kinetics model of upstream oily sludge: Construction procedure and data reproducibility comparison

Abstract

As the dominant hazardous waste discharged from petroleum industry, the pyrolysis features of the upstream oily sludge (UOS) were scrutinized by way of TGA/DSC. The pyrolysis kinetics model of UOS was systematically constructed by sectionalized single-step reaction approach (SSRA) and distributed activation energy model (DAEM), and the data reproducibility was further evaluated. The results showed that when the pyrolysis operation temperature interval was set from 380 K to 1170 K, two weigh loss step, two endo/exothermic regions and three significant mass-loss peak were respectively emerged in TG, DSC and DTG curves, based on which the TG curves could be sectionalized into three stages. Attributing to the ∆E/Eα¯ value of each stage was higher than 10% but lower than 20% derived from the activation energy assessment, it is not only revealed three multi-step reactions were carried out in sequence with an individual dominant single-step reaction which was sufficient for the SSRA utilization, but also displayed a well fitted by the Gaussian distribution which satisfied the requirement of DAEM implementation. Based on the five-step construction procedure introduced in this paper, pyrolysis kinetics model of UOS could be successful established and interpret as SSRA-based and DAEM-based piecewise function. The latter exhibited a better performance on the data reproduction than the former because the nRSS value of the reproduced data derived from DAEM-based model was lower than 1.86%. The higher mathematical flexibility of DAEM-based model function was the major attribution to a better data reproducibility, also, it possessed a potential ability in predicting the reaction rate at an arbitrary reaction temperature once the heating ratio was preset.