Sulfur content in recycle hydrogen of hydrofinishing unit
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I would like to ask everyone for advice. Our plant is a diesel hydrocracking unit, and we are facing a problem: the hydrogen sulfide content in the recycle hydrogen varies periodically depending on the daily temperature. When the temperature is low, the hydrogen sulfide level decreases, and the bypass line of the recycle hydrogen desulfurization tower is almost fully open; in such cases, the hydrogen sulfide content can drop as low as 200 PPM； When the temperature is high, the hydrogen sulfide level increases; the bypass lines of the circulating hydrogen desulfurization tower are almost completely closed, and the hydrogen sulfide concentration can reach up to 600 PPM. I was wondering if anyone has encountered a similar situation
Could it be that the higher ambient temperature causes the temperature of the lean solvent entering the unit to rise, thereby affecting its ability to absorb hydrogen sulfide?
What should be the temperature of the desulfurization lean solution when it enters the desulfurization tower? Do you have control? Still no control?
Generally, it is necessary to ensure that the circulating hydrogen level is 5-6 units lower than that of the lean liquid℃
There is control; the lean solution is kept at 44 degrees
The temperature of the lean liquid remains unchanged, at 44 degrees
On my end, I can’t maintain such a large temperature difference; generally, I keep it within 3 degrees
If it can’t be found due to one’s own efforts, it is recommended to check the amine solution regeneration section
It seems to be affected by changes in high-temperature gas temperature; the air-cooled tube bundle can be cleaned, and a lower desulfurization temperature yields better desulfurization results
The cyclic hydrogen sulfide content has always been 0
You may want to monitor whether there are any changes in the system temperature after air cooling, the feed temperature of the amine solution, the concentration of the amine solution feed, and the amount of amine solution fed