Hydrogen transport and nitrogen transport
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Everyone, I have a question that I hope you can help me solve: Hydrogenation units can operate with cold oil or hot oil, as well as with cold nitrogen or hot nitrogen. I’m confused here: which of these two steps comes first, the one before starting work, or the other? I’m also very puzzled as to why there are cold transport and hot transport methods I hope all of you can offer some help.
Nitrogen first, then oil; cold first, then hot. Thermal transport is closer to actual operating conditions.
The cold oil operation of the hydrogenation unit is carried out after the water circulation operation, to establish circulation in the feed oil. Then the furnace is turned on to raise the temperature and establish a cycle, with all flanges and pipelines being heat-tightened at a constant temperature of 250°C. The reaction system of the hydrogenation unit is purged with nitrogen, and the compressor is tested to prepare for future operation. During the heating of the furnace and the circulation of nitrogen, the catalyst is dried at this time.
Oils are much more permeable than water; they do not leak during transportation by water, but leaks can occur when transported by oil. The purpose of transporting oil is to prevent leaks in the equipment. When a new facility starts operating, with both new equipment and new staff, any type of accident could happen. Transporting oil also serves as a way to train new employees in their roles. For our new facility, the operating procedures include oil transportation, but we have never carried out such operations before
Nitrogen is mainly used for initial pressure building, leak detection, and catalyst drying； In the case of oil transportation, it is mainly to wash away the impurities within the system (such as the trays in the distillation section or catalyst dust, etc.)
Oil transportation tests all pumps and motors, removing water from the system to enable subsequent temperature elevation for hot-state testing. N2 at low temperature is used for rough airtightness, at high temperature it is used for drying, and then there is hydrogen airtightness
Thank you very much to everyone for your answers; I really learned a lot today……
Erquan, which Jade Emperor do you belong to? Heze or Zibo?
Nitrogen is used for initial purging, airtightness testing, and drying of the reaction system; cold oil operation and hot oil operation refer to the distillation section. The oil transfer in the reaction section is called sulfurized oil circulation, which facilitates the stabilization of the reaction at its initial stage.
What the original poster refers to as cold nitrogen operation and hot nitrogen operation means the airtightness of nitrogen in the reaction system, while cold oil operation and hot oil operation refer to the oil circulation in the distillation system