Regarding questions about high-temperature dechlorination in the reforming pre-hydrogenation section, everyone is welcome to share their views
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Dechlorination in the reforming unit takes place in two locations: high-temperature dechlorination after the pre-hydrogenation reactor, and low-temperature dechlorination using reforming hydrogen. 1. If dechlorination is intended to address issues related to ammonium salt clogging and corrosion, then why isn’t water injected before heat exchangers such as those used for pre-hydrogenation product feed or air cooling? (Water injection lines are generally provided, but they aren’t actually used.) 2. Could the high-temperature dechlorination process be moved after the pre-hydrogenation feed heat exchanger? This would reduce the temperature from 230 to 110, which is favorable for dechlorination (lower temperatures facilitate the adsorption of aluminum oxide), and it would also reduce investment costs
High-temperature dechlorination after the pre-hydrogenation reactor, low-temperature dechlorination of reforming hydrogen
First question: The precipitation of ammonium salts occurs within a certain temperature range, and the location of the water injection point depends on factors such as the raw materials used in the device and the process flow； Second question: This approach is also viable, but considering factors such as device pressure drop, the load on the recycle hydrogen compressor, and the process for replacing the dechlorination catalyst, this approach has no advantages in many aspects
Regarding the second point, if the high-temperature dechlorination section is moved after the pre-hydrogenation feed heat exchanger, it will be difficult to deal with the crystallization of ammonium salts in the heat exchanger. A lot of pre-hydrogenation still takes place with water injection between the heat exchangers. It's purely a personal opinion. :)
Regarding the first point, the location for pre-hydrogenation water injection is usually chosen between the pre-hydrogenation feed heat exchangers; the injection point is selected near the dew point temperature of the medium, which allows for the flushing of ammonium salts while also preventing corrosion caused by hydrogen chloride at its dew point.
The function of the pre-hydrogenation dechlorination tank is to adsorb inorganic chlorine, ensuring that downstream equipment is not corroded by HCL. Different temperature levels involve different types and amounts of dechlorinating agents. This requires communication with the dechlorinating agent manufacturer. However, regarding the location of the dechlorination tank, it is generally placed after the pre-hydrogenation reactor; but it can also be located between the feed heat exchangers. I have never seen it placed after the heat exchangers. In my opinion, this is mainly because HCL forms acid only at the dew point of water, thereby causing chlorine corrosion to the equipment. Therefore, high-temperature dechlorination is chosen.