Wet weather flow pumping station

[Lan123]

I am trying to find out the types of pumps that can be used at a 200 mgd 150 ft head Wet weather flow (some municipal sewage inflows also can be exepcted) pumping station.

So far I have vertical end suction, submersible, archimedean screw (If the lift is low), horizontal spilt case (though mainly used in clear water applications). Are there any other pumps that I can add to this list?

Thanks in advance

 

[jamesengineer]

It depends on a few other factors.

What will the maximum solids content of the fluid be?
Progressing cavity pumps are good for large solid contents.

Will these pumps be drawing from a well or tank?

How many pumps will there be? 200MGD is a big old pumping station.

Main types of pumps are centrifugal,Progressing cavity pumps, archimmedes, ram pumps.



"Two hands working can do more than a thousand clasped in prayer"

 

[DubMac]

Lan123

Look at Non-Clog pumps. These are typically used in water intake stations which will encounter solids of all types. What differentiates it as a Non-clog is the very wide, open impeller.

When you say vertical end suction, this is probably what you are talking about. WOuld typically be termed a Non-Clog column pump to manufacturers. This same pump end can also be arranged in a horizontal configuration.

The size you are talking about is only made by a few manufacturers: Flowserve (old Worthington), ITT-Goulds, ITT-Allis-Chalmers, Fairbanks-Morse (now Pentair), etc. Go look at one of their websites under the water-wastewater section.

Archimedes won't work at 150' head. Splitcase won't be apllicable if the solids are significant.

Progressive cavity pumps are excellent for this service, but the volumes you are talking about are too big for any to handle.

Another solution would be to look at a macerator or some type of chopper ahead of the pump if solids are very intermittent. That way you might be able to consider splitcases.

 

[bimr]

Axial and mix flow pumps are used for stormwater for flows in excess of 100,000 gallons per minute.

http://www.flowserve.com/files/Files/Literature/ProductLiterature/Pumps/ps-40-3-ea4.pdf

http://www.cascadepump.com/ver.html

http://www.fmpump.com/EngineeredProduct_fm_af_8200.aspx

You may have difficulty finding a suitable pump with the high head that you mention.

 

[bimr]

Most of these wet weather pump stations have some very coarse screens to keep the large items in the water (such as 2 x 4's and logs) from damaging the pumps.

 

[stanier]

Try dry mounted submersible pumps from ABS , ITT Flygt, Grundfos & KSB. You may need some in series to achive the head.

"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.

http://waterhammer.hopout.com.au/

 

[Pumpsonly]

First of all, it is advisable to install multiple pumps for the total flow. The required head is also considered very high for storm water drainage. If it is correct, you will have to go for vertical end-suction pump.This type of pumps are deigned for solid handling capability. Axial flow pump will not give you the required head of 150 ft.

 

[Lan123]

Folks thanks for all your feedbacks.

Jamesengineer: unfortunatly at this point I don't have the solids contents. But the influent will comprise of municipal wastewater, infiltration and road drainage. So the solids can go high. The sewer will be conveying the wastewater to a wetwell. Pumps will be in the drywell.

Dubmac: Agree Non-clog pumps could be a solution.

bimr: I will also be looking at the axial and mix flow pumps and look look at the links you have suggested. Yes there will be a bar rack to prevent large objects damaging the pumps.

Strainer; Dry mounted subs are also a possibility.

Pumpsonly: I will consider what you have proposed. Anyway I will be talking to the pump manufacturers.

 

[bimr]

This application is within the flow range of mixed flow pumps.

http://www.flowserve.com/files/Files/Literature/ProductLiterature/Pumps/ps-40-6-e.pdf

 

[Lan123]

How can the back spining of the pumps prevented during a pump shut down. Can the check valve or cone, plug valves or reflux valves that are coupled to the pump VFD (If any) do the job?

 

[stanier]

Dry mounted submersibles are preferred because your pump station may get flooded. Keep your switch gear above flood level. Rememeber the generators at Fukishima!

I dont see why these have to be mounted vertically as the motors are designed to be submerged. The companies mentioned have the runs on the board in Europe for emergency flood mitigation systems. Pumps are designed to handle sewage. They have non clog impellers that can pass 100mm spheres.

"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.

http://waterhammer.hopout.com.au/

 

[Pumpsonly]

Pumping the flow and head as required with a single pump installation will need a driver of about 6500HP.
By going for multiple pumps installation will offer you with wider choice of pump type, vendors and driver option and most important of all, the availability of the equipment in times need.

Do put all your eggs in one basket..

 

[bimr]

Many of these pump stations have a discharge above the water surface. Sometimes flap gates are used on the discharge

 

[DubMac]

Try a Non-reverse ratchet on the driver to keep from reverse rotation. Cna get them either supplied with motor or as add-on accessory. I think either Falk or Rexnord makes one.

 

[Lan123]

Folks thanks for all the valuable contributions. What are the main difference between a can pump and a vertical turbine pump? Aren't they essentially axial flow "propeller" pumps. Ofcouse VT pump need a sump but not the canned pump.

 

[DubMac]

It sounds like you already know the difference between a canned pump and a vertical pump; there really is none. A canned pump is simply a vertical turbine dropped into a can. This is done for various reasons; not the least of which is to negate the need to build an expensive and real estate hogging sump. API services will use canned pumps to seal the pumpage from atmosphere and to take advantage of handling very low NPSHA services (such as condensate).

Axial flow is a designation that has only to do with the impeller design and can be approximately defined as pumps with impellers with a specific speed of 10,000 or higher. These are large water movers; typically huge volumes, very low heads (usually under 20 or so feet). They are many times called propeller pumps and are almost always single stage.

Mixed flow pumps would be pumps that also move large amounts of water but produce more head than an axial flow, maybe up to about 50-70 feet or so; their impellers would have specific speeds in the range of about 4-10,000. These are usually single stage also, though I have seen a couple of multistage mixed-flows if I recall.

Johnston Pump Company (now swallowed up by Sulzer) used to make nothing but vertical pumps. They had some fantastic engineers (Herman Gruetink, John Dicmas) that put out an incredible amount of writings on everything vertical. If you can locate any old catalogs or papers, you can learn all you need to know about verticals.

Your situation is very interesting in that the head you are trying to generate is much, much higher than typically seen with such large volumes to be moved. I would be interested to hear (if you are able to discuss) more about the reason why the head is so high.

 

[Pumpsonly]

The Non-reverse ratchet on a vertical pump motor does not stop the pump from back spinning caused by back flow of the liquid.
It only prevents the motor from driving the pump in the wrong rotation in case the motor is started in the wrong rotation due to phase reversal or wrongly connected power leads.

The most used method of preventing back flow after pump shut down is with a check valve near to pump discharge and is a must in multiple pump installation with common discharge header.
You did not give details on the make up of the of 150 ft discharge head is mostly friction head or static.

Looks like your project is still at a very preliminary stage.

 

[bimr]

DubMac,

What is the reference that you are quoting for the discharge heads on the axial and mixed flow pumps?

For example, page 6 of this brochure for mixed flow pumps shows discharge heads to 350 feet for mixed flow pumps:

http://www.flowserve.com/files/Files/Literature/ProductLiterature/Pumps/ps-40-6-e.pdf

 

[Lan123]

DubMac,

Although the head is an estimate, yet I believe this value will not deviate very much from the final head. The incoming sewers are very deep which makes the static head to increase. Therefore Pumps need to pump against a higher head. The project is still at its inception. I will keep you posted with more information as we progess.

 

[DubMac]

bimr,
Not quoting any specific references on mixed-flow head capabilities, basing it more on convention. I don't guess I know if there is any true engineering spec or "rule" that defines upper limit of mixed-flow head; as there is with the flow (specific speed). Obviously, looking at the catalog, Flowserve can build a mixed-flow that goes up to 350' (actually they use Cascade bowls/impellers, don't have their own). I wonder if it is using multiple stages; or maybe running pretty fast?? I don't know of anyone else that goes that high in a mixed flow single-stage. Would like to see the individual model information for that bad-boy.

To Pumpsonly: I am surprised at your statement on NonReverse Ratchets. Have used them for many years to do just that: stop the pump from spinning backwards; they absolutely will keep the entire pumpshaft from reversing rotation. Of couse to stop the water from backflowing, a check valve should be installed. As to the reason people use NRR's on verticals; yes, mostly to prevent wrongly wired motor from unscrewing things below. However, the best way to prevent this is to ALWAYS uncouple the pump from the motor anytime electrical work is done; especially in large machines.

Lan123,
One of the first things you should determine would be the amount, size, type of solids you need to handle. This will help determine whether or not you need to go with Non-Clog impellers or not. If you do need to go to Non-Clogs; at your volumes you are looking at very special pumps. They will be ENORMOUS. Non-Clogs are able to handle long stringy solids better than typical Propeller or Mixed flow impellers.

One of the areas you should familiarize yourself with the most are the different bearing arrangements offered by the pump vendors. These will be sleeve types and you should familiarize yourself with the different materials, lubrication designs, and bearing carriers. This may be the area of most differentiation among the vendors.