×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Wet weather flow pumping station

Wet weather flow pumping station

Wet weather flow pumping station

(OP)
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

RE: Wet weather flow pumping station

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"

RE: Wet weather flow pumping station

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.

 

RE: Wet weather flow pumping station

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.

RE: Wet weather flow pumping station

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/

RE: Wet weather flow pumping station

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.

RE: Wet weather flow pumping station

(OP)
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.








 

RE: Wet weather flow pumping station

(OP)
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?

RE: Wet weather flow pumping station

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/

RE: Wet weather flow pumping station

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..

RE: Wet weather flow pumping station

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

RE: Wet weather flow pumping station

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.

RE: Wet weather flow pumping station

(OP)
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.   

RE: Wet weather flow pumping station

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.  



  

RE: Wet weather flow pumping station

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.

RE: Wet weather flow pumping station

(OP)
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.


 

RE: Wet weather flow pumping station

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.


 

RE: Wet weather flow pumping station

Seems a lot of if's but's and maybe's so far, all of which is a comlete waste of time until minimum and peak flows are establised, system head and solids load is sorted out.

200mgd is a meaningless number without knowing min/max inflow rates.
 
Once this is information is available, the appropriate pump companies can then review the project and make meaningful comment and equipment selections.  

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)  

RE: Wet weather flow pumping station

(OP)
Dubmac

The pumps are definitely going to be non-clog type.  

RE: Wet weather flow pumping station

Well that's great news but would be understood by anyone who had any basic knowledge of waste water pumping, now how about something worthwhile, like nim/max flows.

Don't see what all the drama is about, give any decent pump application engineer the right information and a pump selection could be made in a couple of minutes.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)  

RE: Wet weather flow pumping station

Although the very large axial flow and mixed flow impellers we were discussing throughout the post have the ability to pass large solids due to their large passageways, they are not considered true Non-Clog impellers.

Non-clog impellers are very special 2 vaned impellers with rounded leading edges and oversized passageways that help to pass long stringy solids. Long stringy solids tend to accumulate at the impeller entrance and cause problems for the typical 4-5 vaned prop. or mixed-flow impeller with sharp leading edges; especially imbalance.

While in terms of specific speed, a Non-Clog impeller may have the "characteristic curve" of a mixed-flow impeller; the reverse cannot be said. Your mixed-flow turbine "water mover" does not have a Non-Clog impeller; nor does a prop pump.

Non-clog impellers are also extremely inefficient whereas prop and mixed flow impellers typically have the highest efficiencies of all centrifugal class pumps.

The distinction I was trying to make in your influent was whether your application was mostly drainage/stormwater overflow with intermittent waste solids, in which case a prop or mixed flow pump could be very acceptable, or whether the inflow was truly dedicated to raw sewage; whereas you should move to true Non-Clog impellers.

You say the impellers will definitely be Non-Clog and that is your call; so be it. Just remember there certainly is a distinction between the types; and before you get to the finer points of detailed flow and heads, you should be very clear in your mind that you need true Non-Clogs. Power consumption will be greatly affected. I think municipalities are still concerned with money??  



   

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources