Hello everyone,

I would like to answer the question of what the maximum volumetric flow of natural gas is theoretically possible given the conditions. For some context, a control valve on a natural gas feed line was upsized with the assumption that the valve was the constraint of flow in the system. After the valve was replaced to one of larger size, the maximum flow has shown to be less than before on a smaller control valve. The new valve design included an orifice plate downstream of the valve which is the suspected restriction.

To simplify the problem at hand, I would like to calculate the maximum flow possible on the outlet side while completely ignoring this upsized valve and orifice plate. This would rule out that the valve is the restraint and hopefully provide some understanding of the limits of the system.

The feed natural gas line is a six-inch pipe that distributes the flow to 18 one-inch diameter holes. Initially, I attempted to model this scenario as a nozzle in SolidWorks, where the inlet is the six-inch diameter feed at 165 psig, 70F that converges to an outlet with the sum of cross sectional area of the 18 outlet holes. The outlet condition was that the environmental/surrounding pressure is 35 psig. The simulation did not run- stating that the velocity of flow was supersonic. This in turn led me to believe that the problem could be answered by assuming compressible fluid choked flow. I used a Purdue question as a resource (https://engineering....zle_Reading.pdf), but the mass flow of the natural gas was 560.4 kg/min which then converted to 32,980 cf/min. This flow is high and I am not sure if my calculation is correct. The goal is to answer if 20,000 cf/min of natural gas is possible to be discharged on the outlet side. In this problem- I am excluding any major and minor losses, just to be able to answer what is the maximum discharge flow of NG out of these 18 holes, and does it exceed 20,000 cf/min.

I hope that sheds some light on this case. I will clarify what I can if I missed parts. Please guide me on what tools to use to answer this problem.

Thank you!

Sincerely,

ukrche