Calculation of the Methane Pyrolysis Reactor Taking into Account the Non-Isochority of the Process of the Reaction

Based on the results of the analysis of literature sources, the kinetics of the methane pyrolysis process is described. Examples of calculating plug-and-play reactors and mixing reactors for a conversion rate of 0,99 at a methane capacity of 6000 kg/h are given. It is shown that the volume of a plug-flow reactor should be more than 20 times the volume of a plug-flow reactor. Comparison of calculations by kinetic equations for an isochoric process and a process that takes into account the increase in the value of the reaction mass, due to which the formed sample of the reaction of hydrogen. The effect of temperature on the core volume has been performed and the optimum temperature has been chosen 1250°С

Machine Learning-Guided Equations for Super-Fast Prediction of Methane Storage Capacities of COFs

Covalent organic framework (COF) is a prominent class of nanoporous materials under consideration for vehicular methane storage. However, evaluating a COF for its methane capacity involves multiple experimental or computational steps, which is expensive and time consuming. Consequently, the discovery of high-capacity COFs for methane storage is very slow. Here we developed equations for super-fast prediction of deliverable methane capacities of COFs from a small number (3 to 7) of physically meaningful and measurable crystallographic features. We provided a set of equations with different fidelities for on-demand predictions based on the accessibility of crystallographic features. We found that an equation with only three crystallographic primary features, as variables, can predict deliverable capacities of 84,800 COFs with a root-mean-square error (RMSE) of 10 cm³ (standard temperature and pressure, STP) cm^-3 and mean absolute percentage error (MAPE) of 5%. However, the highest fidelity equation developed here contains seven crystallographic primary features of COFs with RMSE and MAPE of 8.1 cm³ (STP) cm^-3 and 4.2%, respectively. With that, we predicted methane storage capacities of 468,343 previously unexplored COFs using the highest fidelity equation and identified several hundred promising candidates with record-setting performance. CUBE_PBB_BA2, a hypothetical COF not yet synthesized, sets the new record of balancing gravimetric (0.396 g g-1) and volumetric (221 cm³ (STP) cm^-3) deliverable methane storage capacities under the pressure swing between 65 and 5.8 bar at 298K. Also, 3D-HNU5, a previously synthesized COF, has shown the potential to achieve the gravimetric and volumetric methane storage U.S. Department of Energy target (0.5 g g^-1 and 315 cm³ (STP) cm^-3) simultaneously with uptakes of 0.755 g g^-1 and 334 cm³ (STP) cm^-3 at 100 bar/270 K.

Machine Learning-Guided Equations for Super-Fast Prediction of Methane Storage Capacities of COFs

Covalent organic framework (COF) is a prominent class of nanoporous materials under consideration for vehicular methane storage. However, evaluating a COF for its methane capacity involves multiple experimental or computational steps, which is expensive and time consuming. Consequently, the discovery of high-capacity COFs for methane storage is very slow. Here we developed equations for super-fast prediction of deliverable methane capacities of COFs from a small number (3 to 7) of physically meaningful and measurable crystallographic features. We provided a set of equations with different fidelities for on-demand predictions based on the accessibility of crystallographic features. We found that an equation with only three crystallographic primary features, as variables, can predict deliverable capacities of 84,800 COFs with a root-mean-square error (RMSE) of 10 cm³ (standard temperature and pressure, STP) cm^-3 and mean absolute percentage error (MAPE) of 5%. However, the highest fidelity equation developed here contains seven crystallographic primary features of COFs with RMSE and MAPE of 8.1 cm³ (STP) cm^-3 and 4.2%, respectively. With that, we predicted methane storage capacities of 468,343 previously unexplored COFs using the highest fidelity equation and identified several hundred promising candidates with record-setting performance. CUBE_PBB_BA2, a hypothetical COF not yet synthesized, sets the new record of balancing gravimetric (0.396 g g-1) and volumetric (221 cm³ (STP) cm^-3) deliverable methane storage capacities under the pressure swing between 65 and 5.8 bar at 298K. Also, 3D-HNU5, a previously synthesized COF, has shown the potential to achieve the gravimetric and volumetric methane storage U.S. Department of Energy target (0.5 g g^-1 and 315 cm³ (STP) cm^-3) simultaneously with uptakes of 0.755 g g^-1 and 334 cm³ (STP) cm^-3 at 100 bar/270 K.

Permeability Changes of Coal Cores and Briquettes under Tri-Axial Stress Conditions

The paper is dealing with the permeability of coal in triaxial state of stress. The permeability of coal, besides coal’s methane capacity, is the main parameter determining the quantity of methane inflow into underground excavations. The stress in a coal seam is one of the most important factors influencing coal permeability therefore the permeability measurements were performed in tri-axial state of stress. The hydrostatic three-axial state of stress was gradually increased from 5 MPa with steps of 5 MPa up to a maximum of 30 MPa. Nitrogen was applied as a gas medium in all experiments. The results of the permeability measurements of coal cores from the “Zofiówka” mine, Poland, and three mines from the Czech Republic are presented in this paper. As a “reference”, permeability measurements were also taken for coal briquettes prepared from coal dust with defined porosity. It was confirmed that the decreasing porosity of coal briquettes affects the decreasing permeability. The advantage of experimentation on coal briquettes is its good repeatability. From the experimental results, an empirical relation between gas permeability and confining pressure has also been identified. The empirical relation for coal briquettes is in good correspondence with published results. However, for coal cores, the character of change differs. The influence of confining pressure has a different character and the decrease in permeability is stronger due to the increasing confining pressure

The Outburst Risk as a Function of the Methane Capacity and Firmness of a Coal Seam

In most coal basins that are currently being exploited, gas and rock outbursts pose a considerable safety threat. The risk of their occurrence is frequently assessed by means of a parameter known as the methane capacity of coal. In a lot of countries, the evaluation of the mechanical properties of coal is conducted by means of another parameter: the firmness of coal. Due to the laboratory investigations and in situ observations carried out by the authors of this paper, it was possible to determine a function space in which the outburst risk can be described as a function of the methane capacity and firmness of a coal seam. This, in turn, made it possible to link the „gas factor” to the „mechanical factor”, and thus provide a more comprehensive risk analysis.