Hydrogen production --- Control of the temperature point for shutting off steam supply

Table of saturated steam pressure versus temperature Note: Pressure is gauge pressure. Pressure in MPa, Temperature in °C: 0.00 – 100.00; 1.00 – 179.88; 2.00 – 212.37; 3.00 – 233.84; 4.00 – 250.33; 5.00 – 263.92

OP, the information provided wasn’t clearly stated; the 350°C mentioned here likely refers to the temperature at the inlet of the conversion furnace tube, that is, the temperature after mixed heat exchange. However, this value is a bit too high. There is a saying that gas supply should be stopped when the outlet temperature of the conversion tube drops to around 500°C; the conversion tube then uses steam for cooling. Steam supply is ceased once the inlet temperature of the conversion tube falls to 250°C, after which nitrogen is introduced for cooling. Objective: Prolonged use of steam for cooling when the catalyst bed temperature is too high can cause the loss of active components in nickel-based catalysts, rendering the catalysts inactive due to spinel formation. The cooling rate of the furnace chamber is limited, typically at 80–100°C/h, while the heating rate is generally required to be 50–80°C/h. Steam cooling usually relies on externally supplied steam; when the temperature is below 250°C, condensation water forms. If liquid water enters the catalyst, it can cause the catalyst particles at the upper layer to become fragmented. Have you ever seen burned stones becoming fragile when wet?

It is sufficient to ensure that the steam temperature is not lower than the saturation temperature at that pressure; generally, it is required to be 30–50°C higher than the saturation temperature! The requirements aren’t that strict; it’s only necessary to ensure that the steam is free of water during the insurance period! It’s best to be around 380-420!

It’s related to the dew point temperature of steam, right?