Hello,

Whenever I think of "slug flow" I immediately think "drain it". If I understand the description of the problem, the pipe is partially filled with product when the nitrogen is introduced. The nitrogen flows through the pipe at a fairly good velocity and it picks up a "puddle" of product (as a slug)and carries it in the direction of nitrogen flow. When the slug encounters any (or every) change of direction (the inside face of the pipe wall at a change in direction) it impacts the pipe wall transferring the flow energy to the pipe - BANG!!! I think you have a choice of thoroughly draining the pipe so that a "slug" cannot be formed or significantly slowing down the incoming flow of the nitrogen. The slug is formed when the "puddle" of residual product accumulates until the surface area reaches a "critical" size. The flow of gas over the surface of the "puddle" causes friction and when the "puddle" becomes large enough that area is great enough the friction allows the flowing gas to "scoop-up" the "puddle" and create a slug. Of course, if the entire pipe is partially (and contiguously) filled with product, slugs can form several places at once.

So, I think the cure is not in damping the energy (a typical approach to true "fluid hammer"), but rather in stopping it before it can begin.

Any other thoughts from my esteemed colleagues?

Best regards, John.