[femomenal]

I currently work in the Facilities Engineering Department of an oil exploration and producing company. As part of an installation project, we are challenged for space as it is a brownfield installation. We want to combine two waste streams and pump both out of the same unit. The two streams are TEG and waste lube oil. Can anyone here give me issue which may arise as a result of mixing and pumping these two streams?
Responses are particularly sought with respect to the effects of this mixture on the pump pressuring them.
All responses are welcome and will be deeply appreciated.

[Arkcon]

Try a search on this sub-forum.  Some months back we had some questions form another oil-field engineer.  See if the responses/resources in that thread help you with your problems.

[curiouscat]

Temperatures? Pressures?

Have you tested miscibility?

[Enthalpy]

Triethylene glycol? The hydraulic fluid is water-based. I expect (do I remember having observed it?) that it doesn't mix with oil. Anyway, the density differs a lot, like 1050-1150 for polyglycol lube, and 800-900 for dense mineral lube oil.

Waste recycling would like them separated.

Both contain additives that may pass from one into the other, but as waste it's a small worry.

If your TEG is a real lube, with all due additives, a pump will accept it easily.

[femomenal]

And if this helps in any way, the TEG is also a waste stream that has been used to dry natural gas coming off an oil well, before the gas is sent to the compressor.
Read somewhere that glycol leaking into moving parts of a pump may result in blackening and pitting of the pump. What I do not know is if this applies to TEG as well.

[curiouscat]

Read somewhere that glycol leaking into moving parts of a pump may result in blackening and pitting of the pump. What I do not know is if this applies to TEG as well.

What is the MOC in the pump?

[femomenal]

Casing: Cast Iron
Impeller: Brass

[curiouscat]

Casing: Cast Iron
Impeller: Brass

So far as I can tell, no potential incompatibility.

Do you have a reference as to why you thought corrosion would result?

[femomenal]

http://www.machinerylubrication.com/Read/193/oil-glycol

See reference above.

[curiouscat]

http://www.machinerylubrication.com/Read/193/oil-glycol

See reference above.

That seems to describe a different situation so far as I can tell. That's gycol destroying lubricating properties.

You will be pumping glycol + lube. Not using the mix as a lubricant.

Totally different ball game. I think.

Not as high Temp. No very tight clearances. No high pressures.  Won't be exposed to thousands of cycles.

etc.

[femomenal]

Hey curiouscat, you respond as soon as I put up my questions. Thanks! Really appreciate your helpful responses.

May come back for more, when I lay my hands on more details. Thank you once again.

[curiouscat]

Hey curiouscat, you respond as soon as I put up my questions. Thanks! Really appreciate your helpful responses.

May come back for more, when I lay my hands on more details. Thank you once again.

Glad to help. 

[Enthalpy]

Then your polyethylene glycol is NOT a lubricant! If used to dry natural gas, it has absorbed water, and possibly has never been a proper lube will all antocorrosion, anti foam, wetting agents and the like - all that make a decent lubricant.

With water absorbed, the glycol will probably absorb H₂S from the natural gas - nothing good for corrosion.

Some time ago I used glycerine+water as a hydraulic oil. It destroyed a pump within very few weeks, despite having the proper viscosity.

I'd suggest to make at least a lab trial with the very liquids from the field but with a cheap pump whose failure has no consequence. Close the hydraulic loop.

[femomenal]

Hello people,

I have been able to lay my hands on more details. Find attached a side-by-side comparism of the two pumps. The pump are quite similar in both characteristics and performance, so either shouldn't have problems pumping the both waste lube oil or TEG-water (formed as a result of the TEG being used to dry natural gas).
The fluids are passed into a sump intermittently but not necessarily at the same time, and pumped out.

The issue comes back to the compatibility of the waste lube-oil and TEG-water. Would they react? Would the TEG "dehydrate" the lube oil and increase the viscosity up to the point where the pump can no longer handle it?
Someone mention something about foaming property of TEG. Don't think this comes to bear here as both pumps are similar anyways.

What do you think guys?

Thanks.

[curiouscat]

I think you'll do fine. Of course, only my opinion.