Gasification Characteristics and Sodium Transformation Behavior of High-Sodium Zhundong Coal

Abstract

The Zhundong coalfield is a newly discovered superhuge coal deposit in China. Zhundong coal is considered as a potential resource for gasification, due to its high reactivity. However, the high sodium content in Zhundong coal could cause serious ash-related problems during its thermal utilization. This study was conducted to investigate the gasification characteristics and sodium transformation behavior of a typical high-sodium Zhundong coal. The gasification performance of Zhundong coal is greatly improved at elevated temperature, which is verified by both thermogravimetric analysis and bench-scale study in a bubbling fluidized bed reactor. Compared to Shigouyi coal, Zhundong coal shows better gasification reactivity at the same temperature, indicating better adaptability of Zhundong coal to fluidized bed gasification. Sodium in Zhundong coal chiefly exists as the water-soluble form. The temperature is a crucial parameter affecting the release and transformation of sodium. With increasing temperature, more sodium is released to the gas phase, primarily in the form of NaCl­(g). Sodium in the gasification fly ash mainly exists as NaCl, and a small amount of NaAlSiO4 is also identified, whereas the major crystalline phase of sodium in the bottom ash is NaAlSiO4. The formation of high-melting-point sodium containing NaAlSiO4 is beneficial for mitigation of bed agglomeration problems during high-sodium coal gasification.

Study on CO2 gasification properties of coal gasification wastewater slurry

“…It can be considered that in the process of high‐temperature gasification, these components have a more specific and complex impact on the thermal environment and the gasification reaction, which needs to be further studied. On the other hand, the results also show that some metal ions lose their catalytic ability due to the formation of complexes during the reaction 38 . Liang et al 39 indicated that water‐soluble, ion‐exchangeable, and HCl‐soluble alkali and alkaline earth metals can improve the reactivity of coal gasification with CO 2 , and insoluble alkali and alkaline earth metals cannot.…”

“…On the other hand, the results also show that some metal ions lose their catalytic ability due to the formation of complexes during the reaction. 38 Liang et al 39 indicated that water-soluble, ion-exchangeable, and HClsoluble alkali and alkaline earth metals can improve the reactivity of coal gasification with CO 2 , and insoluble alkali and alkaline earth metals cannot. In this paper, water-soluble alkali and alkaline earth metals such as NaCl, HCl-soluble alkali and alkaline earth metals such as CaSO 4 and MgSO 4 , and ion-exchangeable soluble alkali and alkaline earth metals such as Na and Ca carboxylates can all promote the gasification process, whereas insoluble alkali and alkaline earth metals (silicates and aluminosilicates) are termed as stable forms, which do not show catalytic activity in the gasification and combustion.…”

Chemical Composition Changes during the Commercial Entrained-Flow General Electric and Gaskombinat Schwarze Pumpe Coal Gasification Processes

“…The possibility of ash deposition and fouling will increase in the syngas purification system of the GSP gasification because of the volatility of Fe and Ca . The modes of occurrence of elements in coal have a remarkable influence on their release and transformation behavior during thermal conversion . The absence of the investigation of the modes of occurrence of elements makes it difficult to discuss their behavior during the coal gasification processes.…”

“…14 The modes of occurrence of elements in coal have a remarkable influence on their release and transformation behavior during thermal conversion. 49 The absence of the investigation of the modes of occurrence of elements makes it difficult to discuss their behavior during the coal gasification processes. 3.4.…”

Catalytic effect of alkali and alkaline earth metals in different occurrence modes in Zhundong coals

“…With the application of the method mentioned above, researchers focused their attention on the transformations and roles of AAEMs with different occurrence modes in the coal thermal conversion process. A number of studies have focused on the relationship between the occurrence modes of AAEMs in coal and their release behavior and ash formation during pyrolysis, combustion, and gasification . They found that some occurrence modes of alkali metals do not result in ash deposition.…”