Why does the sulfur content exceed the limit every time fresh methanol is added?
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The fresh methanol feed inlet is located at the entrance from Section 1 to Section 2 of the thermal regeneration tower. After each fluid top-up, the sulfur content goes a bit high, but it returns to normal after two hours~!
Which part is exceeding the limit? Is it excessive in the lean solution or in the syngas?
This phenomenon is relatively complex; it may be due to changes in the composition of the feed and variations in feed temperature affecting the thermal regeneration tower, which in turn causes fluctuations in the thermal regeneration system and results in methanol of substandard quality. As a consequence, the addition of fresh methanol leads to inadequate desulfurization performance.
Adding new methanol should be done slowly. No, too fast a speed will result in inadequate stripping and regeneration of H2S!
I agree with the view from the 4th floor; the location where methanol is added is inappropriate, which causes fluctuations in the thermal regeneration tower. As a result, the regeneration of lean methanol is incomplete, and the sulfur content in the lean methanol is high, leading to excessive total sulfur levels in the purified gas.
We exceeded the limit when adding methanol last time as well, but we added it directly to the lean methanol tank!
It turns out this problem is quite common; almost every time we carry out fluid replenishment, the levels temporarily exceed the limits. Later, it got a little better after cleaning the methanol storage tank, which was quite dirty
Each time methanol is added, the amount should be controlled; it cannot be too much, to avoid affecting the regeneration process
When making up the amount, keep it under control and avoid excessive amounts to prevent affecting the temperature distribution in the thermal regeneration tower
Most of them are fed into the second stage of the thermal regeneration tower, so no problems should arise. Introduce a small amount of material into the system in a steady manner, and increase the temperature of thermal regeneration in advance during this process.