Regarding the operations of hydrofining
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Under normal conditions without overheating, several companies continuously feed cold hydrogen into the reactor. I would like to know more about this, as in my company we do not require the use of cold hydrogen as long as the temperature can be controlled. One reason is to maintain the amount of circulating hydrogen and its partial pressure at the inlet of the first bed layer; another reason is that in case of any abnormalities, if too much cold hydrogen is used under normal conditions, there will be little room for adjustment. PS: I just saw a post from a fellow member regarding the operation of the inlet temperature; it seems that cold hydrogen is constantly being fed into their workshop, so I wanted to ask that fellow member~!
In general, for modifications involving two reactors, some cold hydrogen is introduced; otherwise, the temperature becomes too high, resulting in poor product quality. Generally, as long as the temperature does not exceed the safety limit specified by the catalyst manufacturer and the product meets the required standards, it is not necessary to use cold hydrogen
My brother is so strange, haha. What kind of hydrogenation is that? How can there be no cooling involved? Wouldn’t the temperature get higher layer by layer? The higher the temperature, the faster the catalyst deactivates.
If the temperature can be controlled and the product meets quality standards, the inlet temperature should be reduced as much as possible to save energy; when the temperature rise can be controlled, as little cryogenic hydrogen as possible should be used, so that enough of it is available to handle any abnormalities. Here, for both gasoline and diesel hydrogenation, cold hydrogen is basically not used, while in hydrocracking, a small amount of cold hydrogen is continuously injected. We encountered a situation where hydrogenation of gasoline caused excessive temperature rise, so cold hydrogen was continuously injected, which led to insufficient amounts of circulating hydrogen; we even suspected that the design team had selected a compressor with too low a capacity. Later, when cold hydrogen injection was stopped and the inlet temperature was reduced, the temperature rise became easier to control, and there was also an excess of hydrogen available
Our cracking unit is constantly fed with cold hydrogen! Minimal feeding into the refining reactor; the most feeding occurs in the first cracking bed, while less feeding takes place in the second and third beds!
In the case of a refining reactor using coke gas and normal gas as feedstocks, it is generally possible to operate without the need for cold hydrogen injection. However, in the case of a reforming reactor where catalytic gas is used as the feedstock, cold hydrogen injection must continue; maintaining an appropriate degree of openness in the cold hydrogen control valve can effectively prevent excessive temperature rise in the bed under emergency situations.
Cooled hydrogen is mainly used to suppress the rise in bed temperature. In a normal reaction, if no cooled hydrogen is used, the bed temperature will increase from one layer to another, causing the catalyst to overheat or even reach critical temperatures. This indicates that the temperature has not yet reached the level necessary for an exothermic reaction to occur. Based on the performance of the catalyst and the properties of the feed oil, it can be concluded that the utilization rate of the catalyst is insufficient, as well as the quality of the feed oil being substandard. As for your products meeting the standards, I think your catalysts haven’t played much of a role at all.