Oxidation Characteristics of the Semicoke From the Retorting of Oil Shale and Wheat Straw Blends in Different Atmospheres

Abstract

A new way of utilizing oil shale is its co-retorting with wheat straw for oil. However, the process generates a great amount of combustible solid semicoke waste. To utilize this waste effectively for heating the retorting process, the current work investigated its oxidation characteristics by employing a combined thermogravimetry-mass spectrometry (TG-MS) system, and discussed the effects of three parameters, including the wheat straw mass fraction of matrix samples, as well as different ambient gases and their O 2 volume fraction, on the oxidation of the semicoke. In the presence of O 2 , the whole oxidation process of semicoke samples mainly consists of two stages: the combustion stage (300-600 °C) in which water, CO, CO 2 and pollutants are mainly released, and the decomposition stage (600-1000 °C) in which carbonates and sulphates decompose to release CO 2 and SO 2 , respectively. In the combustion stage, increasing both the wheat straw proportion of the original sample and the O 2 volume faction can improve the combustion performance of the resulting semicoke blends. In the decomposition stage, the gasification reaction also occurs to produce CO. During the entire oxidation process, semicoke in 21% O 2 /79% CO 2 would give off less NOx and SO 2 than in air. And, SO 2 formation is also influenced by the O 2 fraction, especially above 900 °C.

Interactions of Oil Shale and Hydrogen-Rich Wastes during Co-pyrolysis: Co-pyrolysis of Oil Shale and Waste Tire

“… M exp = W / W 0 M sml = x normalo M normalo + x wt M wt where M exp and M sml individually represent normalized masses of the experimental sample and simulated sample, M o and M wt are the normalized masses of pure oil shale and pure waste tire at the same moment, and x o and x wt indicate the proportion of oil shale and waste tire in the blends’ sample, respectively. Furthermore, four parameters, the starting temperature of the pyrolysis reaction ( T 0 ), the terminal temperature of the pyrolysis reaction ( T f ), the maximum mass loss rate ( R m ), and the temperature ( T m ) corresponding to the maximum mass loss rate, were obtained from both the experimental and simulated mass loss data according to methods in references. , They were used to determine whether there existed a strong interaction between solid blends.…”

“…Furthermore, four parameters, the starting temperature of the pyrolysis reaction (T 0 ), the terminal temperature of the pyrolysis reaction (T f ), the maximum mass loss rate (R m ), and the temperature (T m ) corresponding to the maximum mass loss rate, were obtained from both the experimental and simulated mass loss data according to methods in references. 27,28 They were used to determine whether there existed a strong interaction between solid blends.…”

Remediation with Semicoke-Preparation, Characterization, and Adsorption Application

“…It has its naturally oxidized form occurring as leonardite [ 27 ]. Other described sources include oil shale during retorting processing under high temperatures that have been found [ 28 ]. Oil sands or tar sands have also been investigated as sources for SC production [ 29 ].…”

“…Characterization, therefore, enables identification and understanding of physicochemical transformations of the feedstock material after carbonization such as the establishment of high hydrogen-carbon (H/C) or oxygen-carbon (O/C) ratios. which determine their aromatic growth and maturation [ 28 ]. An understanding of its transformative process is therefore important t as it provides a theoretical understanding for its re-utilization [ 26 ].…”