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Process conditions for the natural gas steam reforming process: (1) Pressure. From a thermodynamic perspective, low pressure is favorable for the reforming reaction. From a kinetic perspective, in the early stages of the reaction, increasing the system pressure is equivalent to increasing the partial pressure of the reactants, which accelerates the reaction rate. However, in the later stages of the reaction, the reaction reaches equilibrium; with high concentrations of reactants, increasing pressure actually reduces the reaction rate. Therefore, from a chemical perspective, the pressure should not be too high. However, from an engineering perspective, appropriately increasing the pressure is beneficial for heat transfer, as it ① reduces power consumption, ② improves heat transfer efficiency, and ③ enhances the value of waste heat from superheated steam. In summary, the methane-water vapor conversion process is generally carried out under pressure, at around 3 MPa. (2) Temperature: From a thermodynamic perspective, the equilibrium concentration of methane is low at high temperatures; from a kinetic perspective, high temperatures increase the reaction rate, resulting in a low residual methane content at the outlet. Due to the adverse effect of pressure on equilibrium, the temperature must be increased to compensate. However, at high temperatures, the material of the reaction tube cannot withstand the conditions, so the conversion process needs to be carried out in two stages. The first stage of conversion takes place at around 800°C, with a residual methane level of about 10% on a dry basis at the outlet. In the second conversion reactor, the temperature is 1000°C, and the methane content at the outlet is reduced to 0.3%. (3) Water-to-carbon ratio: A high water-to-carbon ratio helps prevent carbon deposition, and the residual methane content is also low. Experiments show that when there are no unsaturated hydrocarbons in the feed gas, carbon precipitation occurs at a temperature of 400°C if the water-to-carbon ratio is less than 2; whereas when the water-to-carbon ratio is greater than 2, carbon precipitation takes place only at a temperature as high as 1000°C ； However, when there is a higher amount of unsaturated hydrocarbons present, carbon precipitation will occur at temperatures of ≥400°C, even if the water-to-carbon ratio is greater than 2. To prevent carbon deposition, the water-to-carbon ratio is generally maintained at around 3.5 during operation. (4) Gas flow velocity: A high gas flow velocity within the reaction furnace tube facilitates heat transfer, reduces the temperature of the outer wall of the furnace tube, and extends its service life. When the catalyst activity is sufficient, high flow rates can also enhance production and increase capacity. However, the flow rate should not be too high, otherwise the bed resistance will increase and energy consumption will rise.