CFD Simulations of Allothermal Steam Gasification Process for Hydrogen Production

Abstract

The article presents an experimental laboratory setup used for the empirical determination of the gasification of coal samples in the form of solid rock, cut out in the form of a cylinder. An experimental laboratory set enabled a series of experiments carried out at 700 °C with steam as the gasification agent. The samples were prepared from the coal seam, the use of which can be planned in future underground and ground gasification experiments. The result of the conducted coal gasification process, using steam as the gasification agent, was the syngas, including hydrogen (H2) with a concentration between 46% and 58%, carbon dioxide (CO2) with a concentration between 13% and 17%, carbon monoxide (CO) with a concentration between 7% and 11.5%, and methane(CH4) with a concentration between 9.6% and 20.1%.The results from the ex-situ experiments were compared with the results of numerical simulations using computational fluid dynamics (CFD) methods. A three-dimensional numerical model for the coal gasification process was developed using Ansys-Fluent software to simulate an ex-situ allothermal coal gasification experiment using low-moisture content hard coal under atmospheric conditions. In the numerical model, the mass exchange (flow of the gasification agent), the turbulence description model, heat exchange, the method of simulating the chemical reactions, and the method of mapping the porosity medium were included. Using the construction data of an experimental laboratory set, a numerical model was developed and its discretization (development of a numerical grid, based on which calculations are made) was carried out. Tip on the reactor, supply method, and parameters maintained during the gasification process were used to define the numerical model in the Ansys-Fluent code. A part of the data were supplemented on the basis of literature sources. Where necessary, the literature parameters were converted to the conditions corresponding to the experiment, which were carried out. After performing the calculations, the obtained results were compared with the available experimental data. The experimental and the simulated results were in good agreement, showing a similar tendency.

A Thermal-Hydrological-Mechanical-Chemical Coupled Mathematical Model for Underground Coal Gasification with Random Fractures

“…The drying range of coal is generally 20-300 • C, and the pyrolysis reaction of coal begins to occur after about 300-400 • C. Due to the highest temperature of underground coal gasification reaching more than 1000 • C, the transition from drying of coal to pyrolysis reactions is very fast. There is almost no specific boundary, which can be simplified to the same reaction rate r 1 [32]. Gasification reactions are divided into solid phase and gas phase reactions, and the temperature range is about 500-1000 • C. The coal drying reaction is as follows:…”

The Usage of UCG Technology as Alternative to Reach Low-Carbon Energy

“…During the experiments of brown coal gasification in the mentioned two generators in laboratory, tar samples were taken and analyzed in an accredited laboratory [36]. Table 2 shows a chemical analysis of the individual components of tar from about 650 kg of brown coal, and they were compared with the threshold values for synthetically produced pollutants.…”

A Review of Laboratory and Numerical Techniques to Simulate Turbulent Flows

“…Consequently, this lack of understanding of turbulent flows is possibly the most serious obstacle to reach a systematic description of many important engineering and environmental phenomena. Only to quote some, the reduction in energy losses in the movement of cars (Ferraris et al [9], Palanivendhan et al [10], Igali et al [11], Kurec and Piechna [12]) trains (Wang et al [13] and [14], Zhang et al [15]) and aircrafts (Bollt and Bewley [16], Varshney et al [17], Miller et al [18]), the improvement in the efficiency of engines (Kazmouz et al [19], Balmelli et al [20], Krastev and Di Ilio [21]) and the reduction in their noise (Zhong et al [22], Polacsek et al [23], Jun et al [24]), the dispersion of pollutants released in the atmosphere (Bellini et al [25], Huertas et al [26], Defforge et al [27], Di Bernardino et al [28]) or in the ocean (Liang et al [29], Chen et al [30], Lee et al [31]), the weather forecasts (Chiniforoush et al [32], Tsiringakis et al [33], Verbitsky and Khodzinskaya [34]), the atmospheric boundary layers (Di Bernardino et al [35], Lu and Li [36], Tkachenko et al [37]), Barbarosa et al [38]),the mixing and combustion in chemical reactors (Soto et al [39], Janoszek and Masny [40], Mularski and Modli ński [41]), the optimization of turbines (Pacciani et al [42], Duthè et al [43], Yang et al [44]), the study of the air flowing through the lungs (Wu et al [45]…”