For the reformation pretreatment unit, what is the basis for choosing full-range hydrogenation or partial hydrogenation?
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As the title suggests: for the reformation pretreatment unit, in some cases distillation is carried out first followed by hydrogenation (partial hydrogenation), while in other cases hydrogenation is done first and then separation (full fraction hydrogenation). What is the basis for making this choice? What are the differences between these two processes?
In my opinion, for reformation processes with a low throughput and a single feed source – such as when only straight-run oil is used as the raw material, with relatively constant impurity levels that do not change significantly – fractional distillation followed by hydrogenation is appropriate. For reformation processes with high throughput, where the raw materials have a high degree of selectivity and impurity levels can vary greatly, full-range hydrogenation should be used in order to protect the reformation catalyst and ensure the ability of the plant to operate over extended periods of time.
The main consideration is the handling of tail oil; if untreated tail oil is to be processed in the plant, it must first be fractionated and then hydrogenated. If it is to be used as feedstock for ethylene cracking, it needs to be hydrogenated first
What was said upstairs makes sense; it mainly comes down to the utility of dewaxing oil (which contains sulfur). However, if it is to be used as feedstock for ethylene cracking, hydrogenation is not necessary, as ethylene cracking units are not sensitive to sulfur. Even when the sulfur content is low, sulfur still needs to be added.
It turns out that hydrogen desulfurization is not required for ethylene cracking; it’s probably to ensure loading safety