Sulfur penetration in hydrogen production reactors
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When sampling the hydrogen peroxide desulfurization reactor, hydrogen sulfide was found inside – could it be that the catalyst has been penetrated? What caused it?
Use a few new sampling bags to take samples of the gas after desulfurization, as well as samples of the feed material before it enters the desulfurization reactor. Generally, if a certain number of samples can be obtained, it’s time to replace the catalyst.
If the process conditions meet the requirements of the desulfurization reaction, it is likely that the catalyst has been penetrated; it is recommended to replace the desulfurizing agent
What is the sulfur content? Aren’t these values within the normal range? If penetration occurs, it is necessary to switch to a desulfurization reactor to prevent poisoning of the conversion catalyst.
Analyze the export content, and then check whether the sulfur content in the raw materials exceeds the limit
By checking the raw material control parameters and conducting comparisons through sampling, it is acceptable for the level to remain within 0.5PPm during one shift; however, it might be due to an incorrect sampling method or errors in the measurements. Re-sampling for analysis is possible, and if the levels are still above the limit after three such analyses, it is necessary to modify the reactor and replace the catalyst online.
Analyzing trace amounts of hydrogen sulfide is quite difficult; generally, when measuring total sulfur, the accuracy is less than 0.5 ppmv. If laboratory analysis is to be accurate to less than 0.1 ppm, it is not possible at the moment. To monitor the sulfur content in zinc oxide at the outlet, in addition to analyzing the outlet sample, it is recommended to regularly analyze the sulfur content at the inlet as well. Then, the sulfur capacity of the zinc oxide bed can be calculated to determine its actual capacity; generally, the designed sulfur capacity for zinc oxide is 30%. By performing cumulative calculations, it is possible to assess the absorption capacity of the bed. Additionally, it is necessary to pay attention to whether the sulfur content at the inlet might suddenly increase (far above the design value); under the same space velocity, a sudden rise in the inlet sulfur content can lead to sulfur penetration. Usually there are two bed layers, one for absorption and the other as a guard bed. If it is monitored and operated properly, there will be no problems. We have been in operation for 13 years without any instances of penetration occurring. A reminder: pay attention to the accuracy of the analytical data from the laboratory. The sulfur content at the outlet of the zinc oxide reactor has exceeded the allowable limits significantly, yet the analytical data still showed normal values; this led to the poisoning and deactivation of the conversion catalyst – a very valuable lesson!