Issues regarding pressure control of the hydrocracking feedstock buffer tank
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The pressure control of the raw oil buffer tank in our unit is achieved using gas; I would like to ask if any other gases can be used as well. Also, doesn’t CH4 in the gas easily cause an increase in the catalyst bed level once it enters the reactor? Thank you
No, if it enters, it will only lead to a decrease in the purity of the recycled hydrogen; in other words, the probability of it entering is very low.
Some units use nitrogen; a small amount of it can enter, as part of what is dissolved in the feed oil. The quantity is very small and will not affect the bed temperature. Since the requirement for recycled hydrogen is that its methane content should not exceed 0.5%, this small amount has no significant impact
Nitrogen can also be used! CH4 has little impact on the crude oil!
Our factory uses nitrogen, and the results are very good. Personally, I think using gas to control pressure is not as safe in terms of preventing leaks as nitrogen.
Using nitrogen for control yields good results, but the cost is high; therefore, dry gas (natural gas) is currently used more often, and it also gives satisfactory results. As for methane, it mainly affects the purity of the recycled hydrogen, and in small quantities it has no impact on the catalyst.
The pressure control of the crude oil buffer tank is achieved using gas; the CH4 in this gas does not cause an increase in the catalyst bed level when it enters the reactor. After all, methane is already present in the recycle hydrogen, so it has no effect on the catalyst bed level. Nitrogen gas can also be used, but its effect is not as good as that of propane gas.
Our device is protected by nitrogen, which is fine; as long as the control valve works properly, not much nitrogen will be used
Firstly, the impact is minimal; secondly, the gas used can be recycled, saving resources!
The pressure control of the crude oil buffer tank is achieved using gas; the CH4 in this gas does not cause an increase in the catalyst bed level when it enters the reactor. Methane is also present in the recycle hydrogen, but it has no effect on the catalyst bed level. Nitrogen gas is also commonly used, but its effectiveness is not as good as that of gas.
From an economic perspective, nitrogen is not as good as gas； In terms of safety, gas is inferior to nitrogen. Methane that enters the bed is mainly dissolved in the feedstock. The actual amount carried into the reactor is limited, resulting in a limited impact on the bed temperature.
Both gas and nitrogen work; both have low solubility in wax oil. For pressure control, it is sufficient to maintain a positive pressure to prevent the wax oil from coming into contact with air, thereby preventing its oxidation
Even if it’s designed that way, try not to use it; instead, use nitrogen. 1) Gas is too dirty; 2) It’s unsafe
Hydrocracking units are generally controlled using fuel gas at the top, and the control is based on pressure difference. This post was last edited by Yang Hanlin on 2009-3-9 at 22:26
The design takes into account the fact that some plants lack sufficient nitrogen resources; therefore, gas is used for pressure supplementation, and this is done with the aim of saving energy
Nitrogen is also used. Gas protection is used to prevent oxygen from reacting with the aromatics and olefins in the oil, thereby avoiding the formation of sediment. Methane in the fuel gas does not enter the reaction system.
It is not methane that has a strong impact on the catalyst, but rather carbon monoxide and carbon dioxide in the fuel gas; the reaction of these substances with the catalyst to produce methane is an exothermic reaction that can make it difficult to control the temperature of the catalyst bed