Abstract
In this work, char gasification of two coals (i.e., Shenfu bituminous coal and Zunyi anthracite) and a petroleum coke under a steam and CO2 mixture (steam/CO2 partial pressures, 0.025–0.075 MPa; total pressures, 0.100 MPa) and CO2/steam chemisorption of char samples were conducted in a Thermogravimetric Analyzer (TGA). Two conventional kinetic models exhibited difficulties in exactly fitting the experimental data of char–steam–CO2 gasification. Hence, a modified model based on Langmuir–Hinshelwood model and assuming that char–CO2 and char–steam reactions partially shared active sites was proposed and had indicated high accuracy for estimating the interactions in char–steam–CO2 reaction. Moreover, it was found that two new model parameters (respectively characterized as the amount ratio of shared active sites to total active sites in char–CO2 and char–steam reactions) in the modified model hardly varied with gasification conditions, and the results of chemisorption indicate that these two new model parameters mainly depended on the carbon active sites in char samples.
Highlights
Gasification is an important technology for the clean and efficient utilization of coal, petroleum coke, and other solid fuels, and is available for large-scale industry due to its high efficiency, high production intensity, and near-zero pollution emission [1,2]
The gasification of three different chars under a mixture of steam and CO2 was carried out using a Thermogravimetric Analyzer (TGA)
Initial gasification rates of these three chars all increased as steam partial pressure increased or as CO2 partial pressure decreased
Summary
Gasification is an important technology for the clean and efficient utilization of coal, petroleum coke, and other solid fuels, and is available for large-scale industry due to its high efficiency, high production intensity, and near-zero pollution emission [1,2]. Fundamental research of gasification processes identified the rate of char gasification as a significant factor controlling gasification behaviors. This was mainly attributed to the relatively slow kinetics of char–CO2 reactions and char–steam reactions under gasification conditions [3]. Chars are reacted with the gasifying agent mixtures consisting of steam and CO2. The researchers in [12] investigated the gasification reactivities of metallurgical coke in a mixture of steam and CO2 , but it was hard to analyze the intrinsic char–CO2 –steam reaction because the particle size of the tested samples was large (3–6 mm), which resulted in the effect of internal diffusion. Muhlen et al [13]
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