Gas pressure and flow rate
Thread Content
Is there an inevitable relationship between pressure and flow rate in gas pipelines? For example, after passing through the pressure regulating valve, the pressure decreases and the pipe becomes thicker – why is it designed this way? What happens if the pipe does not change in diameter?
After pressure reduction, if the diameter remains unchanged, too high a flow rate will lead to an increase in pressure drop. In addition, some media also suffer from erosion corrosion.
Under the same conditions, higher pressure results in a greater pressure difference, and thus a faster flow rate. After pressure reduction by the pressure regulating valve, the pressure difference increases and the flow velocity rises; the pipe becomes thicker. This is done to reduce the flow velocity, thereby minimizing erosion of the pipeline and protecting it.
In a gas pipeline, with the same diameter and the same volumetric flow rate, pressure has no relation to flow velocity. After passing through the pressure reducing valve, the pressure downstream of the valve is low, the fluid density decreases, which results in an increase in volumetric flow rate; if the diameter is not increased, the flow velocity downstream of the valve becomes too high. Only when the pipe becomes thicker and the flow velocity downstream of the valve drops to normal levels can the operational requirements be met.
Agree with the opinion from floor 3! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
Oh, I see. I remember that during the recent inspections to check the pipe wall thickness, they focused on elbows and areas where the diameter changed.