The sulfur content exceeds the limit after desulfurization in the hydrogen production plant
Thread Content
The main feed conditions are as follows: 1. Hydrogen purification off-gas (25,000 NM3/h) + pre-hydrogenation light naphtha (distillate oil) (25 t/h); 2. Hydrogen purification off-gas (25,000 NM3/h) + pre-hydrogenation light naphtha (distillate oil + residue oil) (25 t/h); 3. Hydrogen purification off-gas (25,000 NM3/h) + saturated liquefied gas (26 t/h); 4. Natural gas. At present, two desulfurization tanks are in use for desulfurization treatment after the hydrogenation catalyst; these two tanks are operated in series. The sulfur content at the outlet of the first tank exceeds the specified limit (it has been in use for over 5 months), while the sulfur content at the inlet of the second tank is within normal limits. The customer specified that the sulfur content at the inlet should be between 65–70 ppmv. The volume of desulfurization agent used is approximately 70 m³. I am not very familiar with the hydrogen production process and its various parameters, so I hope everyone can offer some advice. From which aspects should I consider the issue of excessive sulfur content? Thank you!
The sulfur content in the feed gas is above the limit, and the desulfurizer is saturated! Or the optimal temperature for desulfurization may not have been reached; take a sample to check if there are any issues
What is the inlet temperature of your hydrogenation reactor? And what’s the approximate temperature for desulfurization? Is the temperature not high enough to achieve desulfurization saturation?
A suitable temperature for the hydrogenation reactor is 320–380°C, while for the desulfurization reactor it is 300–360°C. It’s also possible that the sulfur capacity has been exhausted and the catalyst needs to be replaced; generally, a desulfurization catalyst lasts around two years.
A temperature of 320–380°C is appropriate for the hydrogenation reactor, while 320–350°C is suitable for the reaction using zinc oxide as a desulfurization agent. Generally, after desulfurization, the sulfur content in the syngas exceeds the specified limits. After investigating the reasons for this, if it is determined that there are no changes in operating pressure, temperature, material flow rate, or impurity concentration, then it’s clear that sulfur has penetrated through the desulfurization bed, and it’s time to replace the desulfurization agent.
The sulfur capacity of the desulfurizer has been saturated; replace it. Pay attention to analyzing the sulfur content in the raw materials