Regarding the airtightness acceptance criteria for hydrogenation units
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Does any expert know what the acceptable hourly hydrogen leakage rate for a hydrogenation unit is in terms of gas tightness? I’ve seen cases where a leakage rate of ≤0.15 MPa per hour under static pressure is considered acceptable, and others where ≤0.45 MPa per hour is deemed acceptable. Are there any specific standards or formulas for this? Thank you
This is the standard for a hydrogenation unit in China: Shut off the hydrogen supply valve and observe the dynamic pressure drop; if this value is greater than 0.3 MPa/h, continue to check for leaks and tighten relevant connections.
We require a pressure drop of greater than 0.17 MPa/h
We require the pressure drop to be no more than 0.04 MPa/h
Air-tightness evaluation criteria: 1. All flanges and valves must be airtight at low temperatures; no bubbles should appear when tested with soapy water. 2. During the hydrogen pressure test of the reaction system, once the specified temperature is reached (if the reactor is equipped with a catalyst, the reactor temperature is maintained at 150–170 degrees; if it is in the drying phase prior to loading the catalyst, the reactor temperature is 350–370 degrees), the supply of new hydrogen to the reaction system is stopped (after shutting down the hydrogen compressor), and there is no significant drop in the pressure of the reaction system. 3. After the temperature in all parts of the reaction system becomes uniform with no significant changes, the pressure drop of the system should be no more than 0.28 MPa/h, or the leakage rate should be no more than 1.5%.
It’s that book. Could you upload it so I can take a look? Thank you.
The general requirement is that it should not be greater than 0.25 MPa/h; relevant information can be found in the book \"Process Calculation and Technical Analysis of Hydrocracking Units\" written by Li Liquan.
For the hydrogen integrity testing of this hydrogenation unit, it is generally conducted in the hot state rather than the cold state. In the hot state, it is not possible to check for gas leaks using soapy water; instead, a hydrogen detector or paper tape leak detection method must be used. Otherwise, the results cannot be guaranteed.