Water injection issues in continuous reforming units

In actual production operations, we do not add water during the reforming reaction or regeneration.

Water was added during both the reformation reaction and regeneration

During normal production, if only the regeneration section is in use, there is no need to inject water

No water was injected in either the reaction or regeneration sections

This post was last edited by qugd on 2012-2-6 at 21:08. The reforming process involves the catalytic rearrangement of linear hydrocarbons into rings along with dehydrogenation; the active center of the catalyst is usually chlorine, and the loss of chlorine occurs due to trace amounts of water in the reaction system (in reforming reactions, oxygen present as oxides or free oxygen leads to the formation of water). Neither the semi-regenerative reforming process nor the continuous regenerative reforming process involves the intentional addition of water, but due to the loss of chlorine, an appropriate amount of chloride is added using a dosing pump to replace the chlorine that has been lost from the catalyst. This relationship between chlorine and water is called the water-chlorine balance. If the water content in the system is high, it will cause severe chlorine loss, thereby reducing the reforming activity of the catalyst. Therefore, during the processing of the reformed crude oil, impurities and trace oxides in the feed are removed through pre-hydrogenation, while the water content in the feed is reduced to 15 ppm or even lower using a pre-distillation tower (this value can vary depending on the specific process design; 15 ppm is not a fixed value). In addition, the oxygen content in the trace hydrocarbons of the reformation feed should also be monitored in order to estimate the approximate amount of water generated, thereby assessing chlorine loss and determining the amount of chloride that needs to be added. Trace amounts of water in the recycled hydrogen also need to be strictly controlled, as do trace amounts of carbon monoxide and carbon dioxide (continuous reforming typically uses chromatography to monitor these two parameters in the recycled hydrogen); these carbon oxides may be introduced during catalyst regeneration.

I have spent some time working in both IFP and UOP’s continuous reforming units. There’s one thing I’m not clear about: where is water injected during catalyst regeneration? I really don’t know; could it be a new technique? For processes such as reformation water injection, chlorine injection, and sulfur injection, there are specialized injection pumps. As mentioned above, water is generally not injected during reformation for two reasons: Most reformation units in China use a straight-run naphtha pre-hydrogenation process, and due to the limitations of the dehydration efficiency of the stripping towers, the water content in the reformation feed is relatively high. This results in the water content in the reformation cycle hydrogen reaching or even exceeding the standards set by catalyst manufacturers, hence there is no need for additional water injection. II. Due to the water-chlorine balance (those who are not familiar with this should read the UOP General Operating Manual carefully), the higher the water content, the greater the amount of chlorine that needs to be injected. As a result, more chlorine is carried along in the reforming products. This chlorine can cause corrosion in the pipelines and may also form ammonium salts with NH3 present in the reforming products, thereby blocking downstream pipelines. Therefore, most reprocessing facilities prefer to operate at a low level of reprocessing rather than inject water. Of course, if the catalyst suffers severe chlorination damage, it is possible to wash away the chlorine by adding water appropriately, but the capacity of the downstream systems must be taken into consideration.

Water needs to be added when the reforming reaction system is too dry. For the reforming units in the IFP regeneration process, the regeneration system can become too dry, resulting in insufficient oxygen chlorination of the catalyst and a decrease in its activity after regeneration. One of our plant’s IFPII reforming units experienced an issue of an excessively dry regeneration system; a dew point analyzer showed that the water content in the regeneration recycle gas was extremely low, less than 5 ppm. At this point, adding water to the reformation feed has no effect; the water injection point in the regeneration system is located before the electrothermal oxidation, and it is necessary to calculate the correct amount of water to be injected.

As a supplementary note, our company’s IFP regeneration series includes the Regen B process and UOP’s CycleMax; neither of these regeneration methods involves a water injection step. I’m not sure what type of unit is located upstairs – is it a Regen C or a Regen C2 regenerator? I’ve only seen this kind of process described in books; it turns out that such models are also used in China. I’ve learned something new!

Our company is Axens REGEN C-2. The regeneration system injects water before the inlet heater in the oxychlorination zone to control the water-chlorine balance. Of course, there is also a water injection system on the reformation feed pipeline.

May I ask what exactly is meant by \"severe chlorine poisoning\" on the 7th floor? Have you seen it or do you know anything about it? When there is a large amount of chlorine present, if you still inject a large volume of water, what happens as a result? Have you tried that? You certainly aren’t an expert in handling equipment, and your understanding of the relevant processes is also poor.