Temperature of desulfurized lean stream in diesel hydrogenation cycle
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What is the temperature control range for the desulfurized lean stream in the diesel hydrogenation cycle? In our unit, the temperature of the desulfurization cycle hydrogen is 50°C, while that of the lean liquid is around 60°C. The hydrogen sulfide concentration in the cycle hydrogen is 200 ppm. Is there something wrong? Please advise
Keeping the temperature between 30 and 70 degrees is sufficient; higher temperatures significantly reduce the desulfurization efficiency. As the temperature rises, the lean solution also vaporizes, which affects the absorption of hydrogen sulfide. Once the temperature is under control, the sulfur content in the circulating hydrogen can be adjusted by controlling the amount of lean solution used. Is the hydrogen sulfide level at 200 ppm? Be careful with catalyst reduction
The hydrogen sulfide content in the raw material is around 3000 ppm; it shouldn’t be reduced, right?
The hydrogen sulfide level is too low after desulfurization, which is not beneficial for the catalyst; please adjust the desulfurization system promptly, otherwise the catalyst could indeed be reduced
We are a hydrocracking unit; the LAS temperature is below 20 degrees before it enters the reactor, the temperature of the recycle hydrogen is no more than 16 degrees, and the hydrogen sulfide content in the recycle hydrogen is around 300. Is your LAS temperature a bit too high? That wouldn’t be favorable for absorption, right?
This mainly depends on the temperature difference between the circulating hydrogen and the lean amine solution; normally, the temperature of the amine solution is higher than that of the circulating hydrogen. The higher the temperature of the amine solution, the worse the desulfurization effect, and it may even cause foaming in the amine solution, which further undermines the desulfurization performance. In regards to the situation you described, there seems to be nothing wrong with it literally; you can try reducing the flow rate of the lean amine solution and then analyze the concentration of hydrogen sulfide in the circulating hydrogen, in order to avoid situations where too low a hydrogen sulfide concentration affects the lifespan of the catalyst.
According to the guidelines provided by the catalyst manufacturers, the hydrogen sulfide content in the recycled hydrogen can be reduced to below 100 ppm as long as fresh material is supplied to the system; in this case, the catalyst will not be reduced
Our ammonia liquid temperature is 60 degrees, and the temperature of the circulating gas is around 53 degrees; the temperature difference is within 10 degrees. I think it was mentioned in the technical FAQs that the temperature difference should be kept between 4 and 8 degrees; I can’t remember the exact figures. Before desulfurization, the hydrogen sulfide level was over 20,000, while after desulfurization it was around 1,000. Let’s discuss it
Thank you everyone; the problem has been resolved. By lowering the temperature of the lean liquid to around 40 degrees, the desulfurization issue is solved.
Before desulfurization, hydrogen sulfide levels were over 10,000 PPm; after desulfurization, levels of around 10 PPM are still acceptable