2-Phase, Mult-Orifice, Restricting 'Sparger'...

[dgsbsme]

I am trying to inject flashing (60psig to ~45psig) condensate into an 8"Ø, 180°F Water line. The 60psig condensate tank has a level control valve. I am trying to get someone to convert the controls to Off/On style operation to minimize pressure drop (thus flashing) at the level control valve.

The orifice plate I am trying to come up with will go on the end of an 2"Ø (or 2½" or 3") elbow inserted into the horizontal 8"Ø at its centerline, jetting downstream. Its purpose is to drop the lion's share of the pressure, and to keep the steam 'bubbles' away from the sides of the 8"Ø, 180°F water pipe (Sch 10S St.St.) to prevent cavitation type damage. The thinking is, higher velocity, directed down the centerline will result in smaller bubble stream diameter and condensing before reaching the pipe wall.

I have started by calculating a pseudo-density from the mass flow rate divided by the total volumetric flow rate (at upstream conditions). Then using the total volumetric flow rate divided by the number of orifices (eg. 9 orifices at 3/8"Ø). Someone else suggested figuring steam and condensate separately, each at its own density and using the sum of those calcs... that gave ~4 orifices at 3/8"Ø.
Clearly, no less than one of these approaches is wrong.

Anyone have a quick & dirty solution to this?

 

[dfish67]

Would the heat balance work out if you cooled the condensate by pumping a portion of the 180F water into the condensate line prior to the pressure drop? Maybe you can eliminate the flashing all together and the hassles that go with it (and the disturbing noise).

Damon

 

[sailoday28]

What is the pressure of the 180F water line at the point of injection? Is there other than injection flow in the 8" line.
Is this a typo or range of upstream pressure? 60psig to ~45psig)
What are the elevation differences between condensate source and outlet of orifice? Based on this and line losses-
What are the conditions (P and T and quality) of the condensate upstream of the orifice?
What is the max flow from the condensate tank?

 

[dgsbsme]

The 180°F water line is ~10psig at the point we will be injecting the hot condensate. It is carrying ~800gpm of the 180° water. I wish I could inject some into my hot line.

The 60psig to ~45psig is the range from the hot source (60psig flash tank) to the pressure immediately before the orifice plate. I'm looking to drop ~35psi across the orifice plate to minimize pressure drop (and flashing) in the Level Control Valve at the 60psig flash tank. There is some static head helping me as the 60psig tank is ~ 20 feet above the proposed injection point.

The pressure and temperature on the upstream side of the orifice plate should be saturation for 45psig.

There are actually two 60psig flash tanks involved... each with their own LCV and their condensate lines joining down stream (but well upstream of the proposed injection point on the 180° line). One yields 31gpm, the other 20gpm for a total of 51gpm. Flashing that from 60 to 45psig comes out something like 391#/hr flash, 49.7gpm condensate.

I would have preferred to run two separate lines all the way to the hot water collection tank with the LCVs relocated there and a dip tube/sparger below liquid level to conserve all the mass and heat, but that would cost more money... you know the song.

 

[dgsbsme]

Just a bump to check for more ideas...

 

[sterl]

Don't know what the budget constraints are but the 180 deg pipe could be used to cool the flow upstream of the orifice plate and the smaller orifice would manage upstream pressure, effectively subcooling the condensate...Flash could be brought to near-nothing and if I got this about right, it appears that about 12-sq ft of surface would knock out the 391 lbs/hr.

That could take the form of welding a half-pipe at say 5" to the outside of the 180-deg 8" pipe, or is that too pricey?