Capturing of sweating/condensation of pipe 4

[dindang]

Having a 10" line running at 16DegC below ambient temperature of 24DegC.
Its a line running around 16km on a pipe rack.
Normal practice is to provide cold insulation to prevent condensation.
Client wanting to save cost, is asking to explore other ideas to capture the condensate.
One such idea is maybe installing drip pans below the pipe to capture the condensate.
Appreciate if there are other ideas to share.

Thanks.

 

[TugboatEng]

If the pipe is not oriented vertically I think you'll find the drip pan costs more per foot than the pipe.

What is the material of the pipe? Condensation can cause significant corrosion over time. Insulation prevents condensation which prevents corrosion.

 

[dindang]

Unfortunately, it is horizontal most of the time.
Material is carbon steel and I did highlight to client on the corrosion which will result in cost to be much more over time.
However, they insist on proposing alternatives which led me to here.

Thanks very much for your inputs.

 

[1503-44]

It's a bit strange that the pipe is not insulated. I would think that over 16km, a significant change in temperature could occur. How are you keeping the pipe 16° lower than ambient temperature?
What is the real temperature profile of the pipeline? Why exactly is condensation become a problem in this case?

 

[btrueblood]

I would assume that some energy was expended getting the fluid in the pipe cold? And that energy is being lost due to heat transfer along the pipe, before the cooled liquid can get to where its going? Seems wasteful, inefficient, as well as a problem with dripping condensation.

edit: it's a fairly straightforward calculation to determine the lost power due to warming of the (let's assume) chilled water in the pipe, and the reduction in losses if insulated. Compare the costs of running without insulation to the cost to fully insulate the piping, determine the time required to achieve payback of the cost of insulation.

 

[EdStainless]

You need to try to estimate how much water you are talking about.
Remember that once the surface of the pipe has a layer of water the condensation nearly stops.
This means that the paint on the pipe needs to have a very smooth and shiny surface finish.
And now think about the logistics.
You catch trays can't just direct the water back 16km (or even split in the middle as 8km each way)
They would need some slope to assure flow, so they will will have to collect and then have the water flow into
another pipe below for directing to a collection point.
Even if this all lightweight PVC the labor to install it will be huge.
And they won't be getting clean water.
It will be loaded with whatever dirt and dust is in the area.
If there are salts in the soil then they will be in the water.
Sounds like a loser to me.




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P.E. Metallurgy, consulting work welcomed

 

[1503-44]

Right. Better to plant some tomatoes under it.

 

[LittleInch]

Client is stupid.

Not much you can do about tat other than show that the insulation costs X and won't result in corrosion of the pipe or the supports, Not insulating cost X x 3 and requires you to replace the pipe and its supports every 10 years. Plus the contents of your pipe warm up - not sure if this is a good thing or bad thing though...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TugboatEng]

The only way I see this working is to use annular pipes with a blower on one end to keep a fresh supply of air, therefore water coming into the space. This same fan could blow any accumulated water through the system so it could be collected. This will require corrosion resistant piping.

 

[1503-44]

Tomatoes was better.

 

[Compositepro]

Pipe insulation can contribute to sweating problems if it is not selected and installed properly. The insulation must be non porous and sealed to the pipe or you get sweating under the insulation, which then drips out. Insulation makes the pipe surface, and any air contacting the pipe, colder than without insulation. It also prevents evaporation.

 

[mk3223]

IMO, if the process requires to maintain the liquid at "colder" temperature, the cold insulation should be installed on the pipe.
Otherwise, the alternative is not to insulate the pipe. If this's okay to the piping in term of the material design, why to worry the condensation?