Wastewater from the diesel hydrodesulfurization unit
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This post was last edited by sxf1028102800 on 2023-7-31 at 14:00. Regarding the reflux tank at the top of the diesel hydrocracking distillation column, part of the naphtha that comes out of this tank, along with some wastewater, is there any chance that this water is acidic? Where does this water usually go?
The wastewater coming from the top of the diesel hydrocracking distillation column is usually sent to a wastewater treatment system for processing. During the treatment process, wastewater is generally treated using physical, chemical, or biological methods to remove harmful substances such as organic matter and heavy metals, so that it meets environmental discharge standards. As for the acidity of the wastewater, it depends on the amount of acidic substances generated during the diesel hydrocracking process. During diesel hydrogenation, some acidic substances may be generated, such as hydrogen sulfide. However, in practice, measures are taken to reduce the formation of these acidic substances, or neutralization is carried out by adding alkaline agents. Therefore, the wastewater coming from the top of the diesel hydrodesulfurization fractionator may be slightly acidic, but it will not be strongly acidic. .
This post was last edited by qugd on 2023-8-21 at 12:55. If it’s water that has been separated through stripping, it may be acidic or neutral; in very rare cases, it could be alkaline (if ammonia is the main component, or if ammonia is injected at the outlet of the stripper to absorb hydrogen sulfide). This depends on the composition of impurities present during the hydrogenation process. Is it too troublesome to measure it with a pH test strip or a pH meter?
It is necessary to check how the process of the distillation system is set up; if the process involves stripping first and then distillation, the wastewater from the top of the distillation tower contains little to no hydrogen sulfide, and it can be used as water for injection in the reaction section and sent to the water injection tank； In the case of a process that involves distillation first followed by stabilization, the hydrogen sulfide concentration in the wastewater at the top of the distillation tower is very high; this wastewater must be sent to an acidic water stripping unit for treatment before it can be reused.
This water is not sulfur-containing wastewater; we call it oil-containing wastewater, which is generally used for injection.
It’s indeed acidic water. Two-phase separation and recovery can be achieved using static equipment liquid-liquid coagulators; feel free to discuss this further.
You’re called acidic water, but its pH value is usually on the alkaline side. This type of wastewater is referred to as sulfur-containing wastewater, and it is sent directly to the sulfur treatment unit for processing.
The main stripping tower located before the distillation tower removes almost all of the SN. The water in the reflux tank of the distillation tower is generally referred to as condensate water, and it is typically used as water for feeding into the reaction process