Influence Mechanism of Water-Soluble Sodium on Zhundong Coal Pyrolysis

Abstract

An inherent water-soluble sodium-loaded coal sample was prepared using crown ether for this study. The pyrolysis process of an inherent water-soluble sodium-loaded coal sample and a water-soluble sodium compound-loaded coal sample was researched by thermogravimetric analysis (TGA). Also, the pyrolysis kinetics of the coal samples were analyzed and researched by the distributed activation energy model (DAEM). The results show that the inherent water-soluble sodium is mainly concentrated on coal particles, which further aggravates the degree of the pyrolysis reaction. The presence of sodium can promote the weight loss of coal samples in the preliminary stage of pyrolysis and the thermal condensation stage, block the escape of volatile matter during the main pyrolysis period, and inhibit the process of graphitization of char. The activation energy of pyrolysis increases with the carbon conversion rate, and the presence of sodium can reduce the activation energy under the same carbon conversion rate.

Co-Gasification Synergistic Characteristics of Sewage Sludge and High-Sodium Coal

“…This phenomenon is mainly because sodium can inhibit the evolution of coal char to graphitization in the process of thermal condensation, promote a high degree of disorder of the coal char microcrystalline structure, and facilitate the gasification reaction. In addition, sodium can erode and slot the surface of coal char particles during the gasification reaction, increasing the surface active sites and active surface area of coal char, and thus promoting the gasification reaction. , …”

“…In addition, sodium can erode and slot the surface of coal char particles during the gasification reaction, increasing the surface active sites and active surface area of coal char, and thus promoting the gasification reaction. 21 , 22 …”

“…In addition, sodium can erode and slot the surface of coal char particles during the gasification reaction, increasing the surface active sites and active surface area of coal char, and thus promoting the gasification reaction. 21,22 The theoretical TG curves of the samples were calculated according to the experimental TG curve of SS and CC by the weighted average method, 30 as shown in Figure 7. It can be seen that different coal blending ratios lead to different TG curves of samples, but the change trend of the whole gasification process is basically the same, which can be divided into three stages: drying desorption stage (50−250 °C), slow gasification stage (250− 750 °C), and fast gasification stage (750−900 °C).…”

“…High-sodium coal is prone to contamination and slagging during direct combustion and utilization, which hinders the efficient utilization of high-sodium coal. , However, the sodium element in high-sodium coal has a catalytic effect on the gasification process . Therefore, co-gasification of sewage sludge and high-sodium coal is conducive to the energy utilization of sludge, improving the calorific value of combustible gas, and providing a new way for the clean and efficient utilization of high-sodium coal.…”