Let’s discuss how to address the issue of excessive temperature rise in residue hydrogenation

It’s also residue oil; waiting for an expert to answer, hello to the original poster

I encountered this phenomenon once, where there was a localized temperature spike in a single bed layer; the exact cause was not identified. But it must be a problem with the raw materials; later I collected multiple samples of the raw materials and found no abnormalities. The most likely reason is that the raw material contains moisture or some other emulsion in certain areas; it is believed that such problems will not occur if the source of raw materials for large-scale installations is stable. If you need a pro, just look for a supplier! Require the source of raw materials~~~~~~~~~~~~~~~~~~~

It’s impossible to cool down after a temperature spike using just this amount of cold hydrogen; if it’s a true temperature spike, the temperature won’t drop unless there’s an urgent release of gas! After a few minutes, localized special reactions will surely cease, heat production will stop, and as a result, the temperature of the large amount of circulating hydrogen will drop! I still think it’s the emulsion causing the problem; as for what exactly it is, I guess I’ll have to ask those experts who specialize in darkening diesel!

How was it resolved, and what was the outcome?

This post was last edited by xgdhnlh on 2015-12-23 09:53. First, we need to analyze the process of residue hydrogenation; if it is residue hydrorefining, no spike in temperature will occur. Although the desulfurization and denitration reactions are exothermic, the sulfur content in the oil is limited, and these reactions will stop once the sulfur has been completely removed, that is, when the exothermic reaction associated with desulfurization comes to an end. Denitration, on the other hand, is the most difficult reaction among those carried out using current refining catalysts, so a significant rise in temperature cannot occur in a short period of time. Additionally, since no cracking catalysts are used, the conversion rate of the oil is very low, with only minor amounts of thermal cracking taking place. The devices where excessive temperature rises occur are primarily hydrocracking units. The cracking reaction of oils is an endothermic process; however, the heat released by the cracking catalyst during hydrogenation is much greater than the heat absorbed. As a result, when the temperature rises, it facilitates the progress of the cracking reaction, simultaneously leading to a vicious cycle of increasing temperatures within the reactor. This is what causes excessive temperature rises, allowing extremely high temperatures to be reached in a very short time. In the early stage of temperature rise (when the temperature increase in the bed is slight – within 10°C), this issue can be resolved by increasing the speed of the recycle hydrogen compressor, raising the flow rate of hydrogen used for quenching the bed, and simultaneously reducing slightly the outlet temperature of the reaction heater. If the bed temperature and its rate of increase are not brought under control, then it is necessary to consider activating the emergency pressure relief system.

I remember that the information I saw stated that in the hydrogenation refining stage of residue or coal tar, a large temperature rise can easily lead to excessive temperature elevation.

I think the information you’re looking at is quite old; catalysts are constantly being improved, and developers have long been working on ways to prevent the catalysts from reaching excessive temperatures. It is correct that the temperature rise in the refining section is significant, but the refining section transfers heat to the cracking reactor, which in turn causes the temperature in the cracking reactor to rise excessively. One can look at cases where such excessive temperature rises occurred – they all took place in the cracking reactor, not in the refining reactor. Therefore, in normal operation, current catalysts generally do not need to account for the risk of excessive temperature rise in the catalyst, unless the manufacturer insists on operating it beyond the designed parameters, in which case it is a separate matter!

Sorry, I’m only interested in the latest coal tar hydrogenation units from the past two years: lol. And I may not know much about other things, but catalysts are my specialty. In processes like coal tar hydrogenation, after hydrorefining, there are separation units such as hot high-pressure and cold high-pressure units, before proceeding to the hydrocracking unit; so how can a large amount of reaction heat from the refining stage be carried over to the cracking stage? Furthermore, if you can find a catalyst manufacturer in this world who can guarantee that no temperature spikes will occur in the fixed-bed hydrorefining section, please tell me their name. If such a miraculous catalyst really existed, why would anyone develop fluidized bed or slurry bed systems for the hydrogenation of low-quality oils such as residue and coal tar?

Contrary to what you said, what really troubles manufacturers is the problem of excessive temperature rise in the refining section; several such incidents have occurred in the past two years.

Haha, thanks! There are new sections and content to learn from now*.