The issue of the location for high-pressure water injection in diesel hydrogenation units
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In our unit, the high-pressure water injection point is located at the high-temperature exhaust outlet, while in many other units it is situated at the air-cooling inlet branch. What are the advantages and disadvantages of this? Thank you everyone.
Your method is prone to causing bias flow.
Generally, there are two water injection points in the design: one at the air-cooler inlet and the other at the inlet of the heat exchanger before the air cooler. During normal production, it is mainly used at the air-cooling inlet. Ammonium salts also crystallize at around 150°C; if there is an increase in pressure drop in the heat exchanger before air cooling, water injection should be resumed. Water injection into the heat exchanger affects its heat transfer efficiency.
At the air-cooling inlet -- in front of the hydrogen mixing heat exchanger--
The setting of the water injection points is very strict. To effectively flush the sediment, water flushing should be arranged upstream of where wet ammonium chloride may form. In the new device, a reasonable estimation of the chloride content can be used to determine the initial deposition point. If the water injection point is positioned too high, it will increase water consumption; sometimes the high oil temperature can cause the water to boil, which requires more water to be injected in order to ensure that at least 20% of the water remains in the liquid state. Whether to choose a single water injection point or multiple ones (for example, one injection point at each inlet of multiple sets of air coolers) involves many factors, which usually need to be analyzed one by one.