Temperature in the desulfurization tank drops by 50 degrees in natural gas hydrogen production
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I’m seeking help from fellow industry professionals. In our company’s natural gas hydrogen production facility, the inlet temperature of the zinc oxide medium-temperature desulfurization tank is 410 degrees, while the outlet temperature is only 360 degrees; in other words, the temperature does not increase after passing through the desulfurization tank, but instead decreases by 50 degrees, which is a rather significant drop. Before the desulfurization tank, there is a cobalt-molybdenum hydrogenation converter, and the temperature rises by 2 to 3 degrees there. The sulfur content at the system inlet is only 20 to 30 PPM
There are several possible reasons: First, the thermometer is broken, resulting in distorted temperature readings； Second, the insulation effect is poor, resulting in excessive heat loss in winter ； Third, the insulation material absorbs water during the rainy season.
This phenomenon can be divided into several types: the situation mentioned by the experts on floors 1 and 2, where a decrease in temperature occurs due to changes in the ambient temperature; since the heat dissipation area remains the same, a drop in the ambient temperature results in a lower temperature. 2. The gas flow rate entering the desulfurization tank decreases; although the inlet temperature remains the same, the amount of heat carried by the gas is reduced due to this lower flow rate. As this heat is lost through radiation, the outlet temperature drops. Regarding the operating temperature of the desulfurization system, the operating temperature of the cobalt-molybdenum catalyst should be maintained within the range of 350–400°C; as long as the conversion rate of organic sulfur is achieved, it is preferable to operate at a lower temperature. The desulfurization reaction temperature range for zinc oxide is fairly wide, typically between 300 and 400°C. The goal is to monitor the sulfur content at the desulfurization outlet to ensure it meets the specified process requirements; as long as this value does not exceed the limits, a temperature 50°C lower should not pose any problems, although at lower temperatures zinc oxide has a lower sulfur capacity.
There are two possibilities: 1. The sulfur content in natural gas is low, or practically zero, so no heat is released； 2. Insulation issues, instrument problems.
Natural gas contains little sulfur, so it releases less heat.
The sulfur content in natural gas is at the PPM level; even if a reaction occurs, the amount of heat released is very small. If the thermometer is accurate, it indicates that the heat dissipation from the desulfurization tower is excessive, and the drop in temperature is mainly due to heat dissipation.