When coking can happen in mechanical seal
When coking can happen in mechanical seal
(OP)
Hello All:
I would like to know what is the mechanism of hydrocarbon coking in the atmospheric side of the mechanical seal. Does it happen only in hot hydrocarbon? Do we need to use steam quench for low temperature hydrocarbon in order to minimize coking?
Best Regards,
I would like to know what is the mechanism of hydrocarbon coking in the atmospheric side of the mechanical seal. Does it happen only in hot hydrocarbon? Do we need to use steam quench for low temperature hydrocarbon in order to minimize coking?
Best Regards,





RE: When coking can happen in mechanical seal
trust this helps
RE: When coking can happen in mechanical seal
RE: When coking can happen in mechanical seal
Steam quench (Plan 62) is specified to cool the atmospheric leakage and prevent coke formation when temperature is above 177ºC or known coking service.
Probably some coke will be formed on services at lower temperature as the hydrocarbon pass through the hot seal faces. Steam would help to cool seal leakage on the atmospheric side but would also heat up the process side and make the situation worse. Therefore I would not recommend steam quench for the solely reason to minimize coke formation if the process side is less than 150ºC.
In the past, steam quench has also been used with single seal and viscous hydrocarbon (such as asphalt), to keep the products thin and avoid damage at start up. Now a day, due security concern, we would think twice before using just a single seal for high temperature service.
Best regards
RE: When coking can happen in mechanical seal
RE: When coking can happen in mechanical seal
It may take place even at lower temperature if heat generated in Mechanical Seal is not removed properly.
My recommendation would be to go for API Plan 21 , ensuring flushing temperature below 120 deg C. By doing this you may be able to get rid of quenching.
RE: When coking can happen in mechanical seal
RE: When coking can happen in mechanical seal
A nitrogen quench will not cool as well as steam, but will keep oxygen away from the faces to prevent coking.
RE: When coking can happen in mechanical seal
Imagine a slug of water in contact with the hot seal faces- sudden vaporization of the water could be bad- physical shock, and sudden contact with cold water could be bad- thermal shock. Both of these could cause a brittle seal face to fracture.
Steam traps near the seal will help, or an old solution is to wrap the steam line around the discharge of a hot pump.