Temperature rise in diesel hydrogenation unit
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How many reactors are there in each of everyone’s hydrogenation units, and are they connected in series or in parallel? As part of this major renovation of our facility, another reactor was added; now there are three reactors in series. The distillate oil from straight-run diesel as well as that from the reforming reactor – that is, the distillate oil coming out of the first reactor – enters the refining reactor, which is the second reactor, and from there it goes on to the third refining reactor. Due to the temperature rise, the temperature increase in the third reactor bed was significant; a large amount of cold hydrogen was injected, resulting in a very low hydrogen-to-oil ratio at the inlet of the first reactor. Currently, the pressure drop in the first reactor is 5 kilograms. I wonder if anyone else has encountered this situation – how should optimization be carried out when the plant just starts operating?
The temperature at the second reverse inlet can be a bit higher
I don’t understand what the original poster means: are your three reactors connected in series, or are reactors two and three connected in parallel after passing through the first reactor?
The temperature of the second reactor is determined by the temperature rise in the first one; if the second one rises, the third one will rise even more
Chai Jin is prompted to do this first: the straight-run diesel, along with the distillate oil coming out of the first reactor at high temperature, enters the second reactor, and from there it goes to the third reactor
The temperature distribution in the first two reactors is unknown. To prevent cold hydrogen from forming in the middle, reduce the feed temperature, or operate a portion of the long cycle appropriately
We have two units connected in series: the first unit is used for refining, with a temperature rise of around 60 degrees; the second unit is used for modification, with a temperature rise of only 15 degrees (the product has a low density, so the inlet temperature is kept very low)
The straight-chip feed can be divided into two streams: one stream is mixed with the output from Reactor 1 and fed to the inlet of Reactor 2, while another stream is mixed with the output from Reactor 2 and fed to the inlet of Reactor 3, thereby controlling the temperature at the reactor inlet； Gradually reduce the injection of cold hydrogen to the triple mirror.
The straight-chip feed can be divided into two streams: one stream is mixed with the output from Reactor 1 and fed to the inlet of Reactor 2, while another stream is mixed with the output from Reactor 2 and fed to the inlet of Reactor 3, thereby controlling the temperature at the reactor inlet； Gradually reduce the injection of cold hydrogen to the triple mirror.
1. Try to reduce the inlet temperature of the second reactor in order to lower the inlet temperature of the third reactor. 2. Take a sample of refined diesel for component analysis; if the total aromatic content is low, attempting to lower the temperature of the first reactor may help to reduce coking. 3. After the temperature drops, the amount of cold hydrogen can be reduced, and the light oil ratio in the first reactor can be increased. A too low light oil ratio in the first reactor will accelerate the coking process; this light oil ratio must be maintained, as a too low value will affect the degree of reaction. 4. Have the pressure and speed of the circulating hydrogen reached their maximum values? If so, then with the addition of another reactor and an increase in the processing volume, has it been re-evaluated whether the recycled hydrogen and fresh hydrogen can meet the operational requirements? If that doesn’t work, we can only reduce the amount of processing slightly.