The binary interaction coefficients between sulfur and H₂S, CO₂or CH₄are not constant, but temperature dependent. Three-parameter temperature-dependent equations for the binary interaction coefficients between sulfur and solvents are proposed.

The study of hydrogen concentration distribution law of hydrogen-doped methane pipeline is directly related to the safety and stability of hydrogen-doped methane pipeline network. Based on the theory of fluid dynamics, this paper established a model of hydrogen-doped methane pipeline and simulated the operation and shutdown status of hydrogen-doped methane pipeline by adopting the computational fluid dynamics method and selecting the mixture multiphase model and standard k - ε turbulence model. This paper investigates the hydrogen concentration distribution law in hydrogen-doped methane pipelines as well as the influence law of different hydrogen-doping ratios, operating flow velocities, operating pressures, shutdown time and gas usage on the hydrogen concentration distribution in gas pipeline. The results show that: under the operation condition, there is a weak uneven distribution of hydrogen in the pipeline, the hydrogen-doping ratio, flow velocity, pressure on the hydrogen volume fraction of the change in the 0.9% or less, the effect can be ignored; in the shutdown status, there is a clear stratification phenomenon, the hydrogen-doping ratio increased from 10 to 25%, the change in the volume fraction of hydrogen in the 11.2% or less, a positive correlation; with the extension of the shutdown time to 900s, the pipeline firstly appeared obvious stratification phenomenon in the branch pipe, the thickness of the gas with hydrogen volume fraction above 40% on the upper wall surface of the branch pipe increased to 0.7 mm, and after the shutdown time was extended to 10 h, obvious stratification phenomenon appeared in the main pipeline, and the volume fraction of hydrogen near the top of the main pipe of about 16.5 mm was above 30%, which was positively correlated; In the shutdown status, the shutdown time has the greatest effect on the stratification phenomenon in the pipe, followed by the hydrogen-doping ratio, and the gas usage has the least effect.

The effect of gathering pipeline pressure, temperature, and key components on the solubility of monomeric sulfur in high-sulfur-content natural gas is directly related to the prediction and prevention of sulfur deposition in surface gathering pipelines. Based on our previous study on a prediction model of sulfur solubility in gas with a new formula for the binary interaction coefficient between sulfur and H₂S, a new gas–solid thermodynamic phase equilibrium solubility prediction model for monomeric sulfur in high-sulfur-content natural gas was improved based on the gas–solid phase equilibrium principle considering both physical and chemical solution mechanisms. Two new expressions for binary interaction coefficients between sulfur and CO₂ and CH₄, considering both temperature and solvent density, are proposed in this new solubility prediction model. In this paper, the main factors, such as the gathering pipeline pressure, gathering pipeline temperature, H₂S, and CO₂, affecting the solubility law of elemental sulfur in high-sulfur-content natural gas are investigated. The results show that the total solubility of elemental sulfur in high-sulfur-bearing natural gas tends to decrease with an increase in the gathering temperature, in which the increase in temperature promotes physical solution, and the physical solution mechanism prevails. Conversely, chemical solution is promoted, and the chemical solution mechanism prevails. With an increase in the gathering pressure, the total solubility of elemental sulfur in high-sulfur-content gas tends to increase, where the physical solubility decreases slightly at first and then increases continuously, with a pressure inflection point of about 2.0 MPa, and the pressure increase has a significant promoting effect on the chemical solubility of elemental sulfur. The increase in the H₂S concentration promotes the solution of elemental sulfur in the gas phase in general and significantly promotes the chemical solution of elemental sulfur. The effect on elemental sulfur solubility can be neglected when the molar concentration of CO₂ in the gas phase does not exceed 10%.

Soil characteristics have a decisive influence on the leakage behavior of hydrogen-blended natural gas pipelines, the gas migration and diffusion laws, and the hazard range. However, existing studies are mostly limited to idealized and homogeneous soil conditions, failing to truly reflect the key restrictive role of the complex heterogeneity of backfill soil on the leakage and diffusion process. At the same time, there is a significant deviation between the diffusion mode of the leaked gas and the simulation results under normal homogeneous soil conditions. To obtain the physical property parameters of soil heterogeneity, this study adopted soil ring knife tests combined with the kernel density estimation (KDE) method for actual measurements, and used the heterogeneous soil parameters to modify the leakage model of buried hydrogenated natural gas (HBNG). The research results show that the heterogeneity of soil significantly affects the diffusion of leaked gas. The horizontal diffusion range of gas in backfill soil is 0.44 m higher than that in typical loam soil and 0.28 m higher than that in typical sandy soil; with the increase of hydrogen blend ratio (HBR), the mass flow rate of gas in backfill soil shows a downward trend; the average relative error between the gas mass flow rate prediction model established based on soil heterogeneity characteristics and the simulation results is 1.24%. The results of this study can provide numerical reference basis for the optimization of actual engineering schemes.

Hydrogen is an important carrier of clean energy, and its transport through existing natural gas pipeline networks has become an international consensus for large-scale delivery. The existing large-scale, long-distance transportation of natural gas relies on buried pipelines. However, there are significant differences in the physical and chemical properties of methane and hydrogen. Hydrogen mixed into the natural gas pipeline network for transportation may cause hydrogen embrittlement in the pipeline, which can lead to leakage and explosion accidents, causing serious injury to the surrounding personnel and property. In this study, numerical simulation was used to explore the leakage and diffusion laws of buried high-pressure hydrogen-blended natural gas (HBNG) pipelines as well as the initial explosion time (IET) and leakage of HBNG in forming the ground surface explosion zone under different hydrogen blending ratios (HBRs), soil properties, pipeline pressure, burial depth, soil temperature, leakage hole diameter, and other influencing factors. The results demonstrate that soil properties significantly influence the diffusion characteristics of gas leakage. The increases in leakage hole diameter, pipeline pressure, HBRs, and soil temperature all contribute to an earlier IET. The formation of IET is significantly delayed with increasing burial depth. The increase in HBR will lead to a decrease in gas leakage, and the two are negatively correlated. Multivariate function prediction models of IET and mass flow rate were established by coupling multiple influencing factors with average errors of 4.7 and 2.67%, respectively. This study provides a numerical reference for optimizing the maintenance and repair plans and emergency response plans after the HBNG pipeline leakage.