Investigation of the Kinetics of Pressure Coal Char Hydrogasification

Abstract

The authors of the study focused on the problem of hydrogasifying coal extracted from a particular location. Since hydrogen is transparent to radiation, it can only be heated by convection. To achieve this, we developed a swirler and utilized Fluent software (version 19.0) to simulate the primary flow vectors and the temperature distribution of hydrogen in the hydrogasification reactor. The process was carried out under varying conditions, including temperatures ranging up to 1173 K, pressures of up to 8 MPa, and gas flow rates between 0.5 and 5 dmn3 min−1. The results showed that the carbon reactivity of the char was high up to a certain level of carbon conversion. In this study, the kinetic equations of the hydrogasification process were developed based on the theory of active centers. The researchers also evaluated the kinetic constants at the maximum reaction rate for the analyzed chars. The analysis was conducted for four extreme cases of process parameters, which included temperatures of 973 and 1173 K as well as pressures of 6 and 8 MPa. The results showed that the maximum hydrogasification reactivity of chars could be accurately described using equations for both the first- and second-order reactions toward hydrogen. This was likely due to the use of a narrow pressure range of 6–8 MPa during the experiments. The kinetic equations developed in the study could be used to model the process on a technical scale.