High temperature submersible pump

[Ideasworking]

Hello,

I would like to hear from other people who may have experience operating a submersible pump in very hot conditions.

My application is a submersible pump installed in a steam distribution manhole. The manhole fills with ground water and is heated by the steam line. Temperatures above the water level are tyipcally around 400 degree F. The water is obviously boiling. The manholes are located along side a public street and therefore I cannot mount anything above grade level. Hence the reason we are using a submersible pump.

The pumps we have installed in the past are rated for 195 degrees F, so these pumps tend to fail after 30 days. Unfortunately we have not had any success finding a pump with a higher temperature rating.

Can anyone suggest a possible solution?
Thanks in advance.
Lou

 

[MikeHalloran]

Sink an adjacent manhole, put the pump in that, and connect the manholes with a small pipe. That way, the ground will cool the water around the pump and protect the pump.

Without disturbing the surface, you can maybe get the same effect by boring horizontally from the manhole bottom, putting the pump in that chamber, and almost closing off the chamber.

Less effective, but maybe good enough: Divide the manhole at the bottom, again isolating the pump in a closed chamber with much of its external surface exposed to ground temperature.

Easiest to install: Put the pump at the bottom of a double- walled pipe, with just a small hole at the bottom to let in heated water. The jacket will probably need its own bilge pump unless you seal it, pressurize it with nitrogen, and install a pressure gage for monitoring. I'd probably trap a layer of foil between two layers of batting inside the jacket, too.






Mike Halloran
Pembroke Pines, FL, USA

 

[Ideasworking]

Thanks Mike,

All very good suggestions. We did sink a manhole adjacent to one of the manholes. However due to easement restrictions along the street the adjacent hole had to be fairly close and the water was still very hot. This is Canada and there is never snow above this steam line.

I will give your other ideas some thought.

Thanks,
Lou

 

[TenPenny]

One possible option would be a steam powered pump, like the Spirax Pressure Powered Pump. Don't know if it could work in your situation, though.

 

[Ideasworking]

Hello TenPenny,

Thanks for the response. Your suggestion is appreciated. Unfortunately we tried that and the minerals in the water baked to the pump forming a large clump of calcium and other minerals.

Just in case anyone else is reading this thread. I'm also interested in a level detection system for these manholes. So far we have tried floats, capacitance probes, and combination of current sensing relay and timer.

The plastic floats melt and the metal floats build up with mineral deposits.

The capacitance probes also fouled with mineral deposits very quickly.

The timer and current sensing relay has proven to be the best so far. The timer picks up once and hour and if the motor draws enough current the current sensing relay latches it in till the water is removed and the pump's current draw falls off. The problem with this solution is that the motor may run when there is no water. Which quickly shortens the life of the motor.

If anyone has some thoughts they would like to share, please do.

Thanks,
Lou

 

[MikeHalloran]

On second thought, the jacketed sump pipe won't work unless you have a way to get some heat away from the pump, e.g. a heat pipe or a cold water flush or something like that.

;---

Given the boiling water, I wonder if there's a way to rig up a percolator.

...

you've almost got one there. Suppose, and I'm really just speculating now, this might be a really bad idea for other reasons, suppose you sealed the top of the manhole and set it up so that the only vent was through a sparge pipe to a drain? Would the steam above the water push the water out?






Mike Halloran
Pembroke Pines, FL, USA

 

[Ideasworking]

Interesting idea...

I should apologize... I should have started this thread with more information. I don't think I could seal this concrete manhole well enough to have steam pressure buildup enough to push the water out. There is a 20" casing with a 12" steam line and a 6" condensate line running through this manhole. The cassing to the steam line is sealed with a link seal...well sort of sealed with a link seal and ground water pours in.

Thanks for the suggestion.

 

[JRLAKE]

I don't think protecting the pump from excessive temperature alone is going to help. Whenever you pump a boiling fluid the pump is going to suffer from cavitation.

 

[MikeHalloran]

Good point re cavitation; however, actual failure mode has not been stated.

Maybe an old fashioned steam driven reciprocating pump could work, if the mechanism were continuously submerged in, and lubricated by, the condensate. Has that ever been done?







Mike Halloran
Pembroke Pines, FL, USA

 

[pauljohn]

Just a thought on the high water switch.

Could you feed a tube into the water, fix a pressure switch at the top and let the rising water set of the switch by compressing the air in the tube. This way you could just have a bare metal tube in the water and all your electrical/switches etc. you could plumb wherever you wanted.

You could even fit a membrane in the tube somewhere so the switch itself was protected if necessary.

 

[pauljohn]

Now I'm thinking if you have major temp. fluctuations you would have a tough time setting the trigger point of the switch. You could only use this method if the pressure in the tube stayed fairly constant except when the water level changed.

 

[MikeHalloran]

-OR-...

Ditch the submersible pump. Forget the float switch. Install an eductor in the bottom of the manhole, and pump water through it continuously. Effluent will be water until the manhole is drained, then water/air/steam.
Of course, you'll need to install a pump somewhere, to power the eductor, and provide a flow of water.

Better, use a steam- powered ejector to do the same thing.

You seem to have plenty of steam available.

;-)



Mike Halloran
Pembroke Pines, FL, USA

 

[d23]

Ideasworking

We don’t know the flow required or space you have available, but you can get submergible motors from the petroleum industry that are rated for 400 degree F.

http://www.bakerhughes.com/centrilift/

http://www.slb.com/content/services/artificial/index.asp?

http://www.weatherford.com/weatherf...nts/production/esp_espsystemapplications.hcsp

Have you considered a vertical turbine where you have a vertical motor mounted above the water?

D23

 

[Ideasworking]

Hi d23

Thanks for the post. I have contacted the vendors you suggested.

Happy Holidays!
Lou

 

[EdStainless]

I see that d23 beat me to it. Centrilift and Reda both build sub pumps that will run in 400F and higher conditions. We used to run in wells as hot as 500F bottom hole (550F internal motor temp).

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Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[thewellguy]

Sun-star motors in Lubbuck Tx will also make submersible motors for high temp apps. I use then for standard water well motors, but I know they do high temp motors also.