Slug Flow in steam/condensate return line

[david6245]

Hello,

I have a 265 psig steam/condensate line return from a heat exchanger back to a flash steam drum. It is about 5 wt% vapor/95 wt% liquid, and 80 vol% vapor/20 vol% liquid. Liquid velocity is 3.5 ft/sec; steam velocity is 15 ft/sec.

We are experiencing slug flow as evidenced by regular oscillations in condensate flow/drum level/steam drum makeup valve opening, not to mention a visibly swaying pipe. The pipes were designed for 2-phase flow using the Baker Chart.

We are trying to remedy this problem now and I would like to ask for advice on the best way to mitigate the effects of slug flow. Placing a restriction orifice at our steam drum does not help reduce the amount of vapor due to our available pumping head and cooling requirements.

Will providing additional piping support do anything besides keep the pipe from failing catastrophically? Will we still have our oscillating flow?

Any help is greatly appreciated.

 

[SeanB]

Unfortunately steam/condensate systems can be very difficult. Do you have a control valve in your system? If it is located near the exchanger one option is to relocate the valve downstream as close as possible to the flashdrum to keep back pressure on the system and minimize flashing. Another option is to look at your current line size and either having to increase or decrease a line size to try to get you out of the slug flow regime.