Chloride content in hydrocracking feedstock
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Dear sea friends, what is the chloride ion content limit for the raw materials used in your company’s hydrogenation reforming units? What are the adverse effects of high chloride ion levels on the operation of the device? Could you give some advice? Thanks first!
Firstly, a high chloride ion content can have a toxic effect on the catalyst; it is necessary to consult with the catalyst manufacturer. Secondly, an excessive chloride ion level causes corrosion to the equipment, which is detrimental to safe production.
Post-Louis can cause chloride salt blockages; meanwhile, if the equipment is made of stainless steel, extra care is needed, as chloride ions are corrosive to stainless steel
Chloride ions must be strictly controlled in the hydrogenation feedstock, as they can corrode austenitic stainless steel
First, it is harmful to the catalyst, causing it to become poisoned; second, it is corrosive to the equipment; third, it forms ammonium salts that can clog the equipment.
The strict control requirement is no more than 1 ppm, with the maximum allowance increased to no more than 3 ppm.
State-owned enterprises such as Sinopec generally enforce strict controls with limits set at no more than 1 ppm; however, this is indeed difficult to achieve for local refineries that lack raw materials. It’s impossible to say exactly what level is safe – there’s no guarantee. Keep it as low as possible; enhance thickness measurement on the device.
This post was last edited by uyouu1 on 2015-9-7 09:00. Vacuum and atmospheric pressure electrodesalination is used to control the chloride ion content in the feed oil (with the actual salt content kept below 3 ppm); the chloride ion content in the feed hydrogen depends on the dechlorination efficiency of the upstream units (dechlorinating agents). When chloride levels are high, they react with ammonia to form ammonium salts that clog the hydrogen pipelines and heat exchangers; in severe cases, the amount of circulating hydrogen drops sharply, leading to shutdown. Of course, corrosion beneath the scale resulting from the deposition of ammonium salts is also something that needs to be taken into account.
The high chloride ion level is mainly caused by ammonium chloride crystals blocking the heat exchangers, as well as chloride-induced corrosion and corrosion beneath scale deposits. Ammonium chloride crystallizes at a high temperature, so it starts to crystallize even before water injection; excessive pressure drop forces shutdowns. Moving the water injection point forward can help alleviate this issue, but high-pressure heat exchanger tubes are prone to leakage, so duplex stainless steel could be an option. The most important thing is to control the chloride ion content in the raw materials – the lower, the better. If it’s not possible to keep it low, it should not exceed 20 PPM (based on experience; we have encountered such cases before).
Chloride ions cause severe corrosion to equipment! ! Moreover, it generates a large amount of ammonium chloride, which clogs the air coolers and heat exchangers. Additionally, it is also toxic to catalysts.
An increase in the chloride ion content of the raw material directly affects the KP value of ammonium chloride; at the same temperature, crystallization is more likely to occur. This is why, at the same location and temperature, an increase in the chloride content of the raw material leads to the crystallization of ammonium salts. Once ammonium salt crystals appear, water injection measures or a switch to water injection should be taken promptly. When injecting water, it is necessary to adjust the speed of the circulator immediately, as sudden changes in pressure drop will cause the entire system to operate faster, resulting in an increase in the amount of circulating hydrogen.