New Orleans Pumps 2

[unclesyd]

I caught the tail end of an interview where it was mentioned that the electric motors that run the drainage pumps are 50 cycle and they have to have a special power plant up and running. I have a lot of information on the drainage system but no mention of the type motors except that the last pump installed had a synchronous motor.
I was just wandering if this true.

This is curious as my home near coal and ore mines and steel mills had a lot of 50 cycle equipment. In fact the company towns around the mines and mills had 50 cycle power, free, so everything electrical had to came from the company store.

 

[itsmoked]

Nice looking solution. Why can't they just sling with rope only 3k pounds?

 

[rmw]

Back to the early afternoon conversation, at such time as the levee's are repaired and ready to hold water, in addition to the installed pumps, they will bring in pumps from outside to augment the existing pumps. IMHO

rmw

PS, and on our nickel

 

[rmw]

A good report here:

http://www.nola.com/newslogs/breakingtp/

Check the post at 8:23 PM by Mark Schfleifstein titled "Surge, breach and 26 foot gouge"

rmw

 

[icelad]

Please help a poor dumb CIVILian

Thanks to SlideRuleEra excellent link I was reading on the New Orleans pumping system. I then Goggled some more and saw that they ran at 25 Hz (some articles had 50 Hz)

Couple of questions

Is there some advantage to running the motors like this….. like the speed vs torque trade off in gearing ( 10 speed bikes for example)

Do they need local generators for this or what kind of equipment do they use to change the cycles of the 60 Hz.

How does this work with the phasing etc


jraef

Reading on the capacity of these pumps... All 21 stations have a capacity of pumping a total of 47,000 cu ft of water per second times 7.48 for gallons times 60 for minutes times 60 for hours times 24 for days == 30,374,000,000 gallons per day compare this to Nashville Water (where I work) the water system (aprox 2600 miles of pipe) puts out
162,000,000 per day max of fresh water 162 MGD vs 30,374 MGD whew also 1,000,000 gallons equal 3.07 acre feet so the pumps whould drain 30,374 acres of water (47 and a half square miles) 3 feet and one inch deep per day

John

 

[itsmoked]

icelad [3 feet and one inch deep per day] that's certainly better news whew.

 

[jraef]

icelad,
Excellent math work there on the pumping capacity, although I am not going to double check it! I't's still 6-7 days of ALL of the pumps working and no more rain.

If you read one of my posts above, the oldest are/were 25Hz because that was one of the first power systems designed in the US, and NO jumped all over the concept early on to solve their problem. Yes, they had dedicated generation systems for them, those are down too of course.

This website gives a decent explanation as to why 25Hz was "chosen" in those early days.

http://www.technology.niagarac.on.ca/people/mcsele/Rankine.html

Apparently much of the equipment for NO was bought and moved from the Niagra area.

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[icelad]

I dont know the acreage of the basin but I the internet had 199 square miles 127,360 acres so 127,360 times 4 feet?? of flood water average 510,000 acre feet of water 165,900 million gallons pumping at 30,000 per day about 5 and a half days if they dont blow the levee and only pump it out all these are real rough figures but gives a general idea

John

 

[electricpete]

I am trying to put in perspective for myself the significance of the failure of those pumps.

If it takes perhaps 7 days or more to pump down the city but only a matter of hours to initially fill it up, then the pumping capacity would be insignificant compared to the rate of inrush of water through those breaches, right?

So it wouldn't have mattered whether pumps worked or not. The city would still be flooded. Do y'all agree with that conclusion?

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[icelad]

I would think the pumps where never meant to protect against levee breaks but was a method to pump the storm water run off out of the basin six inches of rain water would take a half day or so
John

 

[itsmoked]

electricpete no question, I agree in light of almost a mile of missing levee. Levee trumps.

It's just too bad the pumps weren't all mounted on tethered floatation with flexible hose so if a levee failed they would stay functional or at least onsite and not damaged. Instead of being drowned rats.

 

[electricpete]

That makes sense. You don't design pumps to cope with levee breaks, you design levee's not to break.

Just to clarify, I didn't mean that it is insignificant whether pumps work once they get the breaches fixed (that will be important).... I meant that it was insignificant that a few pumps malfunctioned on Monday since the present flooding situatio would be the same even if they had worked.

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[macmil]

I have to imagine that a significant amount of the pumping capacity is now compromised, mainly from the electrical supply aspect not to mention the pump motors if they were submerged, plus possible damage to the discharge piping. In view of the time required to inspect and repair that damage, I think that barge or pontoon mounted pumps powered by diesel generators with flexible and portable discharge piping could make a start, once the levees are repaired.

 

[dpc]

Keep in mind that these pumps have to pump **everything** out of New Orleans, not just water coming through the levees. Every drop of water from any source that goes into New Orleans must be pumped out.

The pumping system was never designed to deal with a major levee failure. It was sized to handle normal water inflows plus a major rainstorm.

An article in the local paper's website (

http://www.nola.com)

indicated that the Sewerage Board was working on critical pump stations to get them ready to run once the levee is plugged. However, it also said that the power plant they need to run the pump motors is not yet working.

 

[itsmoked]

I think that's right dpc. Isn't there a nuke they pulled the plug on pre Katrina?

http://www.nrc.gov/reading-rm/doc-collections/news/2005/05-031iv.html

Quotes:

[As a precautionary measure, the Waterford 3 nuclear plant near Taft, La., shut down when a hurricane warning was issued for St. Charles Parish on Saturday. It remains in an Unusual Event, the lowest of four emergency action levels. Electrical power for key safety systems on site is being supplied by the plant's standby diesel generators, following a loss of off-site power caused by instability in the regional electrical grid.]

Of interest:

[The Grand Gulf nuclear plant near Port Gibson, Miss., and River Bend Nuclear Station near Baton Rouge, La., were both operating at reduced power this morning. The plants operated through the storm, but voluntarily reduced power generation to assist in restoring stability to the electrical grid when a drop in energy consumption caused grid voltage to fluctuate.]

 

[unclesyd]

Supposedly all the pumps are ready to run and are waiting on the levee breach to be fix and last but not least the W&SB generating station to come on line. The statement was that they hope to have it online about the time the breaches are fixed. Supposedly they are going to deliberately breach the levees in a couple of areas to let some of the water run out by gravity. Hope it works.
These pumps would be hard to put on barges as most of them are in the 12' to 14' diameter range. The biggest pumps I've seen on dredges were 6' dia.
The pumps will move most anything in the system. Mr. Wood also invented an excellent sewage pump. His original sewage pumps have run since they were installed in the teens and twenties without ever being taken out of service.

 

[jraef]

Back to your point e-pete, I agree that the pump failures were insignificant in terms or causality, but I think it is now very significant in terms of delayed recovery. Wow, a pontoon float system, what a great idea. Just goes to show the arrogance involved in their thinking that it would never happen, instead of having a contingency plan for it if it did. So many publicly funded projects are like that: short sighted savings in lieu of long term reliability.

We have been having a similar fight on this in the SF Bay Area. After the last earthquake and bridge failure, a plan was made to replace the old Bay Bridge. The new span was designed specifically to withstand an 8.0 quake (maybe more, can't remember). Nevertheless, squabbles and political wrangling over alignment and property values delayed it so long that the cost went up astronomically. Then our “Governator” declared that the state would no longer fund the current design, saying it was too “extravagant” and we couldn’t afford it. His team proposed a cheaper design that would be, guess what, JUST LIKE THE ONE THAT FAILED!


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[itsmoked]

I must give credit to the float-a-pump idea to my better half. She suggested it 5sec after I told her the pumps were underwater.

 

[MikeHalloran]

Floating the pumps would not be so difficult, but where are you going to get a 12 ft diameter suction hose?



Mike Halloran
Pembroke Pines, FL, USA

 

[itsmoked]

Um... Good point. And what is the bending radius on that?!? You could always use rigid with rotating elbows. Means the pump need only be 24 or so feet away normally, then as it floated it would get closer/above.

 

[MikeHalloran]

OH. Duh. If you mount the pump on a barge, it can have a rigid suction pipe that only need extend a bit below the barge's waterline. As it empties out the city, the barge sinks with the water level and eventually comes to rest on a pad in the sump.

So all you really need is a flexible discharge tube. Which actually could be done with rotating elbow joints, or the spherical joints they use in dredge pipes. The joints don't have to be particularly leak- resistant; just let the pump pick up whatever runs out.

Additionally, you may need to put a trap in the discharge tube so the vacuum pumps can prime the pump, so you need a good- size barge. I've been to New Orleans; they've got big barges everywhere in various states of construction and disrepair.





Mike Halloran
Pembroke Pines, FL, USA