Abstract
In view of the high dielectric constant of magnetic nanoparticles, this paper intends to use it as a new type of microwave absorbing medium to accelerate the microwave pyrolysis process of oily sludge. Microwave thermogravimetric reaction and pyrolysis product staged collection devices were established, respectively. The main stage of pyrolysis process of oily sludge was divided based on the thermogravimetric experiments. Mechanism was studied through the characteristics of pyrolysis products and reaction kinetics simulation. Experimental results showed that the addition of magnetic ZnFe2O4 particle did not change the microwave pyrolysis process of oily sludge and the pyrolysis efficiency could be improved. Pyrolysis process was divided into three stages, rapid heating and water evaporation stage (20~150 °C), light component evaporation stage (150~240 °C) and heavy component cracking stage (240~300 °C). Due to the addition of magnetic ZnFe2O4 particles, the content of C4~C12 increased by 3.5%, and the content of C18+ decreased by 4.1%, indicating that more recombinant components participated in the reaction pyrolysis to form light gas components. The kinetic analysis showed that the activation energy of oily sludge decreased by 36.49% and the pre-exponential factor decreased by 91.39% in stage III, indicating that magnetic nanoparticles had good catalytic activity.
Highlights
Published: 9 February 2022Oily sludge refers to sludge mixed with crude oil, various refined oils, residual oils and other heavy oils
The performance and efficiency of microwave pyrolysis are improved to some extent by adding microwave absorbent to oily sludge, the experimental results still show that the pyrolysis conversion or pyrolysis efficiency is still not ideal after adding some microwave medium, and the treatment cost and energy consumption are generally high
The kinetic equation of pyrolysis reaction was first established according to the Arrhenius law, the reaction mechanism function was determined by analyzing the characteristics of microwave pyrolysis products, and the function was solved by Coats–Redfern integral method
Summary
Sludge refers to sludge mixed with crude oil, various refined oils, residual oils and other heavy oils. The performance and efficiency of microwave pyrolysis are improved to some extent by adding microwave absorbent to oily sludge, the experimental results still show that the pyrolysis conversion or pyrolysis efficiency (pyrolysis efficiency refers to the Energies 2022, 15, 1254 percentage of material decomposed into biogas and bio-oil by heating [28].) is still not ideal after adding some microwave medium, and the treatment cost and energy consumption are generally high. This paper intends to carry out thermogravimetric experiments with magnetic nanoparticles combined with microwave pyrolysis of oily sludge on the self-established microwave thermogravimetric reaction and pyrolysis product staged collection devices. The process routine of magnetic nanoparticle enhanced microwave pyrolysis for oily sludge was studied through the characteristics of pyrolysis products and reaction kinetics simulation. This study will be of great significance for giving full exert to the unique advantages of microwaves, strengthening the effect of microwaves and improving pyrolysis efficiency
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