Reasons for leakage in hydrogenation high-pressure heat exchangers
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We ask all fellow sailors to actively share their views on the causes of leaks in hydrogen high-pressure heat exchangers, as well as the precautions to take during startup and shutdown
Internal leakage or external leakage? Internal leaks are usually attributed to corrosion or poor quality, while external leaks can often be resolved by tightening the thread lock ring or applying pressure to enhance sealing – I don’t know that much about equipment-related knowledge.
For threaded lock-ring heat exchangers, pay attention to the pressure difference between the tube side and shell side during startup and shutdown; this pressure difference should not exceed the design value
There are too many reasons for heat exchanger leaks, and they can arise from various aspects; issues such as stress during installation and restricted expansion play a role as well； Regarding the equipment, the materials used for flange gaskets and bolts are not appropriate ； Irreasonable operation procedures, failed pressure testing, medium corrosion, incorrect commissioning steps, etc ； The key points to note at the start of operation are ensuring that the pressure testing is successful, thoroughly purging the shell and tube sections as required. When putting the equipment into use, it is essential to start with cold conditions before moving to warm ones, and to drain any condensate in between. During regular operation, large temperature fluctuations should be avoided; regular sampling and analysis at the inlet and outlet points are necessary. Proper insulation should be maintained. When shutting down the equipment, it should be cooled down first after being heated up, and the equipment should be cleaned regularly to ensure proper maintenance.
It doesn’t specify the type of heat exchanger, nor whether there is internal or external leakage
Locking ring heat exchangers generally experience internal leakage after coming to a stop due to thermal expansion and contraction; even if the inner ring bolts are tightened, the outer ring needs to be thermally tightened once operation resumes.
Our unit has leaked several times due to issues with the tube bundle material. Also, an excessive pressure difference in the reactor might be a factor as well
Let’s talk about the leakage areas of the two HH high-exchange units we have. E103: Internal leakage due to erosion corrosion of the circumferential weld of the tube sheet heat exchange tubes; minor external leakage resulting from the failure of the sealing gasket. The E101 tube sheet backer pad failed, causing internal leakage. It should be noted that the above two diesel hydrogenation units have been in operation from November 2010 to September 2019, for a total of 8 years, without any maintenance
If there are no significant fluctuations in the equipment, and the properties of the crude oil remain stable, it is beneficial for the heat exchanger, with no risk of damage.