Issues regarding the medium-pressure steam generator in diesel hydroprocessing units
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A diesel hydroprocessing unit under construction. A medium-pressure steam generator is located between the hydrorefining reactor and the hydroprocessing reactor. The inlet temperature of the reforming reactor is controlled by regulating the liquid level of this device. I have no prior experience with such equipment; since the boiler feed water relies on upstream systems, if the supply of water is interrupted during operation, the boiler will likely run out of water very quickly. If the water supply is restored later, can water be added directly? Is there any risk involved? I wonder if anyone has similar equipment in their setups. Appendix: The outlet temperature of the first reactor is 360+
I’ve never encountered this setting~~~ It’s definitely dangerous to add water directly to a dry pot; if it’s possible to do so, add water after the temperature has dropped~~~
No piping has been seen on site; it’s not possible to cut it out based on the drawings.
This post was last edited by xgdhnlh on 2015-6-13 at 10:04. Without seeing the drawings and relevant documents, it’s not possible to provide an accurate answer. However, based on your description, there are significant safety hazards in this design: 1. If the steam generator does not have a refined oil bypass line, it cannot be put back into use once the drum runs dry. The process of restarting the drum is similar to that of restarting a heat exchanger – first the cold side is activated and then the hot side; if heat is applied to the hot side without first removing the cooling medium, the cold medium will vaporize instantly due to the high temperature, causing a sudden sharp increase in pressure within the drum. In mild cases, this may lead to the safety valve opening, while in severe cases, explosion could occur； 2. Since the drum cannot be put back into use due to dry-boiling, the inlet temperature of the reforming reactor rises significantly, and there are no means to adjust it. So I think maybe you misread the drawings; the designers wouldn’t make such a big mistake!
There should be a bypass line to adjust the temperature of the cracking section. It is best to remove this. After all, it is heat exchange between water and the reaction products, and a leak is not good for the cracking catalyst.
I’ll take a look on my way by to see if there’s anything I can learn
Judging from the steps for starting the heat exchanger (first introducing the cold stream, then the hot stream), there should be a problem if the intermediate steam generator is reused after it becomes dry. If such a situation occurs, this condition should be taken into account when designing the steam generator, but it may be difficult to do so in practice. Increase the heat exchanger bypass lines or expand the volume of the drum, and improve the reliability of the deoxygenated water supply to avoid such operating conditions.
This is the first time I’ve encountered such a design; in the past, cold hydrogen was used to control the inlet temperature of the reactor. We added a secondary line to our existing cold hydrogen pipeline, opening this secondary line first and then controlling the main valve. If it is designed as you described, and if the drum is interrupted, it will affect the inlet temperature of the reactor; this will increase the amount of cold hydrogen used to control the temperature between the different bed layers, and in severe cases it can lead to a spike in temperature
Not to mention whether water can be supplied directly, even just the heat exposure on the way there would be too much for the heat exchanger to handle; problems are likely to occur