On the application of steam traps for air and water removal in purging pipelines
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This post was last edited by To/For on 2017-11-9 at 22:50. As shown in the diagram, due to winter anti-freezing requirements, it is necessary to purge the water from the pipelines at 4.0 MPa and 2.2 MPa using nitrogen (the steam inlet valves of these pipelines have been closed and blind flanges installed; there is no steam in the pipelines – only water at room temperature). Since check valves function to prevent steam from passing while allowing water to flow, if nitrogen is introduced into the 4.0 MPa pipeline, will it be able to pass through the check valve and enter the 2.2 MPa steam pipeline? Similarly, if nitrogen is introduced into the 2.2 MPa steam pipeline, will it be able to pass through the check valve and enter the 4.0 MPa steam pipeline? I haven’t learned drawing; I just drew it using the drawing software that comes pre-installed on the computer. That circle is used to represent the steam trap – please take it as a rough approximation.
By introducing nitrogen into the 2.2 MPa steam pipeline, as long as the pressure in the 4 MPa pipeline does not exceed 2.2 MPa, the nitrogen should not flow into that 4 MPa pipeline. Flow can only occur in one direction when there is a relative pressure difference.
It depends on the type of trap you are using; generally, the trap does not allow air to pass through.
Thermostatic valves do not allow air to pass through, so there is no such thing as a mixture of nitrogen and water passing through the valve to remove water while allowing air to enter the next outlet; rather, they simply remove water
Your assumed scenario is that there is no steam in either pipeline, right? This depends on the type of steam trap; it’s not necessarily the case
Yes, there’s no steam at all, and nitrogen is filled into only one pipeline at a time