The problem of high salt formation in diesel hydrotreating
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After passing through the reactor, the crude oil enters the heat exchanger, and then proceeds to the high-temperature fractionator. At present, the last heat exchanger in the high-temperature fractionator tends to form salt deposits due to low temperatures, around 170 degrees. The temperature cannot be increased further because of the load on the heating furnace. Is it reasonable to install a water injection system before this heat exchanger in order to carry out short-term flushing under the current conditions? Is there any other way?
Can’t raise the temperature by reducing the amount of cooling source in the heat exchanger, right? . . Then it seems the only option is to modify the injection process; reducing the sulfur and nitrogen content in the raw materials can only decrease the amount of salt formation. I remember an article saying that the salt crystallization temperature can be calculated. I’ll go back and check.
We are also facing the issue of low heat exchange efficiency here, but it is not believed to be caused by salt deposition. We believe it is the scale inhibitor that has caused scaling...
Over 170 degrees; ammonium chloride salts start to form crystals at temperatures below 200°C, so it’s normal for crystals to form at that temperature. After injecting water, how do you separate the water? Who might enter the stripping tower? This could lead to unstable distillation operations; it seems that you’re unable to control the chlorine content in the feed material.
High-rate water injection – the water is separated at high pressures. Control the N and Cl in the raw materials. The Cl content in hydrogen also needs to be controlled
Water indeed enters the distillation system through processes such as heat-driven high-boiling-point fraction removal, heat-driven low-boiling-point fraction removal, stripping, and distillation; the fluctuations in this distillation system are particularly large
Yes, reducing the sulfur and nitrogen content in the raw materials does not solve the problem of salt formation. So where is the most appropriate location to install the water injection points?
It seems that the current approaches to dealing with this issue involve injecting water, and there isn’t a really good solution; it’s just intermittent water injection. We’re waiting for experts to come up with a solution, and we’ll just observe
The water injection point is generally located at the inlet of the heat exchanger. The crystallization temperature of ammonium chloride is around 220 degrees, so it is necessary to ensure that water is injected before this point. In addition, specialized water injection nozzles are required to improve the efficiency of removing ammonium salts.
Do scale inhibitors cause scaling? Isn’t it meant to prevent scaling?