John Crane dry gas seal inscription
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What is the impact of the pressure difference between the primary seal gas and the balance line? What impact will it have if the setting is 180 kp and 250 instead? System pressure 5.4mp
Here, we set it at 0.33 MPa. The outlet gas from the hydrogen circulation pump is used as the primary sealing gas, with a pressure of 7.4 MPa
I’m not quite sure whether the first-stage sealed gas entering the balance tube flows through it or goes inside the machine
The specified synthesis pressure is 0.18, but it’s actually 5.4
Keep flowing – most of it returns to the compressor, while a small portion is vented through the labyrinth secondary seal to the flare. That’s how our regulations describe it
1. An appropriate pressure difference ensures continuous injection of dry gas seal gas into the sealing chamber; once there, it enters the spiral groove of the dry gas seal to form a rigid air film that separates the stationary and rotating rings of the dry gas seal. If the pressure difference is too low, insufficient dry gas seal gas cannot be injected, preventing the formation of a rigid gas film. As a result, the stationary and rotating rings of the dry gas seal cannot be separated, leading to dry friction and damage to the dry gas seal. 2. Setting it at 180 kPa has little impact when the actual operating pressure is 250 kPa; this will result in a higher inlet flow rate for the primary seal. However, over 95% of the gas from the primary seal returns inside the machine, while only a small amount of the gas that leaks from the primary seal, along with the gas from the secondary seal (nitrogen), enters the flare through the primary leak path.