water pumping windmill question 4

[inovermyhead]

Does anyone know the formula for calculating the distance a windmill will pump horizontally?
An 8ft windmill will lift water 180ft with a 1 7/8 cylinder pump. If my static water level is 60ft and the cylinder is @75FT I'm pumping up to the surface 60 ft. I would like to know how far I can pump after that point horizontally. Surely water will move easier horizontally than vertically.
other factors that may influence distance......
1 1/2" pvc pipe at the surface only
drop pipe is 1 1/2" galvanized
I'm at 220 ft above sea level
flow of water is not constant in the pipe
thank you

 

[Apakrat]

wind speeds above 40 mph or below 40mph?

Your shut down for hurricanes only is not a dispute by me.
Just used a guestimate based on grampa's home made wind gage used some 60 plus years ago and info the Internet wind generator people publish.

So what does everyone think?....... dig the tank at 500ft?

My view of condition at 500 ft. The friction loss, when the wind is at 40 mph, is estimated at 4 psi per 100 ft or a total of about 46 ft of loss from original 180 ft height.

This drag, during high wind conditions, could be considered a positive feature, actually acting as a drag-break.

Story- On record are two young Aggie graduates purchasing a large ranch near Jal, NM back in 1968. Seems the ranch had a windmill on about every other square mile an 15" deep native grass except for a circular grazed out area around the windmills.
The young owners scattered water troughs around the total grazing area, connected by gravity flow to the windmills with 3/4" black ABS pipe. Stay with Your windmill.

At 74th year working on IR-One2 PhD from UHK - - -

 

[Artisi]

" BigInch (Petroleum) 6 May 09 12:16
Did I mention sometimes they run in the dark? "

The best reply in Eng-Tips so far this year

 

[HEC]

All great discussion, but you are still missing the point. Where is the windmill operating and what are the prevailing wind conditions? This will determine the best location for the tank. Especially given the power from the turbine (windmill) will drop off approximately with the square of the windspeed. This will not only affect the volumetric flow but also the lift/discharge pressure available.
For the OP 500 ft of pipe is correct if your average wind speeds are around the 15 - 20 mph most of the time. If the winds are less than that for most of the time the windmill will sit there and stall. So the prevailing wind conditions will determine the maximum length of pipe that can be used.

Mark Hutton

 

[Artisi]

Article on windwill/solar pump.

http://www.cometwindmills.com.au/solar_v_wind.html

 

[BigInch]

HEC, Oh no. We're not missing the point and ...

Well ... not exactly.

First, as long as there is wind enough to lift the water to the surface + a bit or so, water will flow in a 1-1/2 inch horizontal pipe. The question then becomes not where to dig the tank, but how big to dig it. With a pipe inlet head of only 1 ft or so, a pipe length (from 0 to [∞]) , you will get a flow, which will be anywhere from 0 to a theoretical max of
piston speed * x-sectional area.

So, since now I managed to make this a question of only how big to make the tank, it demonstrates that tank location is independent of distance from the well head. I guess that's why when you see those nice artistic senia-colored photographs the stock tank is always in the immediate vicinity of the windmill. So, I go back to what Artisi said, "gravity flow to anywhere". If you had a 180 ft tall tank, you could pressure flow if you wanted to too. But he wants his tank far away for some reason, so add some pipe.

P.S. when I run these tiny flowrates in my Churchill program, I get only a few feet head loss, so I'm ignoring the system curve and

Then figuring only a known pump power from the wind and lifting to various heights above static water level, I get these flowrates, attached. Of course the pipe system curve should be added to be technically correct, but I have to do something other than this today.



**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[HEC]

BigInch,

Sorry if I caused offence, it was not intended. I do follow your argument, however if the discharge pressure on the pump is too high the pump/windmill will simply stall. There will be a maximum torque along the constant power curve where the turbine speed will be too low to keep it spinning and the pump will stall. The design point given by the OP is for a "moderate breeze" (4 on the beaufort scale). For some areas this is a good mild day, in relation to wind strength. In other areas the normal wind strength may be much lower, in which case the windmill will be stalled most of the time. This is my point.

Mark Hutton

 

[cvg]

my two cents - from the information provided, lift is 60 feet and pump will theoretically lift water 180 feet during a "moderate breeze". So there is 120 feet of resultant head which equates to approximately 50 psi at the ground surface. even though we don't have a pump curve it is reasonable to assume that the windmill will continue pumping water perhaps to the point that the wind decreases to a "light breeze" while still providing at least a few psi at the top of the well. Since the friction loss in the pipe is quite low at the design flow of 180 gallons per hour and would be even lower at reduced flows, the windmill should continue pumping, at a reduced flow rate even in a light breeze. If a light breeze cannot be maintained for any length of time, than perhaps a solar collector, water wheel or team of horses would be a more appropriate power source for your pump.

 

[Artisi]

http://www.cometwindmills.com.au/C_Pat 1 & 4.pdf

Gravity flow seems the best way to go, look at figure 2 on the above link which shows the discharge from the well above ground level - using this arrangement with the tank at ground level I guess the distance the tank can be form the mill is infinity.

The question really comes down to how far can the pumped flow that is varying from 0 to theoretical max be delivered thru the 1 1/2 pipe line at the variable pressures at the the well discharge enabling a reasonable flow to be maintained with all the variables acting on such an installation?

 

[inovermyhead]

HEC and CVG you are both on the right track, somewhat. HEC, Windmills will always stall whether I'm pumping directly to the surface or pumping a long distance, that is something I cannot control. Windmill owners realize that the windmill will pump 4-5 hours full capacity out of 24 hours. We choose the size of pump based on our water needs knowing that the wind will not blow 24 hours a day. I could have gone a high as a 3" pump which would have delivered 320 gallons an hour at the same wind speed and depth. It is more advisable to go with a smaller pump than needed as it is easier on the windmill motor and the windmill will continue to pump at slower wind speeds.
ARTISI, gravity flow is an option. Now we have another question..........If I were to to use gravity to flow to my tank 500' how high would I need my discharge at the windmill to keep it flowing at a resonable rate in 1 1/2" pvc pipe? I LOVE THIS FORUM!

 

[inovermyhead]

CVG, You stated that there will be 120 ft of resultant head wich equates to approximate 50 psi at the ground surface, is this correct? Please correct me if i'm wrong, the head psi would be determined by how many feet of water is in the pipe above the discharge point. This is an opened ended system. The windmill pulls the water to the surface and the water then flows horizontally. Where will the head pressure come from? Would I now need to install a stuffing box? I could also extend my head pipe (the pipe above the discharge point). My head pipe is 4' above the discharge point. I could extend it to about 20' above the discharge point or install a stuffing box.

 

[Artisi]

How about a tank at the mill at some pre-determined height which you can freely pump into, no stalling of the mill and it also ensures maximum capacity under all operating conditions - from there it can flow by gravity to the distant tank way off in the never-never.

As we don't know the mill flow rate at a head of lets say 80ft (standing water level to the discharge into the primary tank) how about assuming 5GPM - (no need to consider minimum flows) the flow thru your 1.5" PVC line from the primary tank to the final point is a function of the friction loss / distance / head available in the primary tank.

Using 1.5" sch 40# PVC pipe friction tables the head loss at 5GPM is 0.2ft / 100 feet of pipe run.

Therefore, calculating with a head in the primary tank of 20ft the distance from the primary tank to the final destination can be:

20 ft (head in the tank) / (0.2 friction loss per 100ft of pipe) = 100 x 100 = 10,000 ft pipe run.

If the final discharge point is lets say 3 ft above ground level the the available head reduces to 17ft / 0.2 x 100 = 8500ft pipe length.

You will need a stuffing box at discharge of the rising main from the well.

 

[BigInch]

HEC, No problem.

Maybe I just don't understand how you're using the term "stall". The usual IC engine interpretation is stop working, in which case I would assume flow = 0 and windmill rpm = 0. But for a windmill (with wind) rpm not stopped and a power input of P = k * Q * H / eff, and it means H is Max and Q is min for the current wind power output. Theoretically meaning Q and rpm cannot = 0, unless H went to infinity and the pump exploded, OK, yes.

Artisi,

Yes. inovermyhead almost gave the answer. He says "If I were to to use gravity to flow to my tank 500' how high would I need my discharge at the windmill to keep it flowing at a resonable rate in 1 1/2" pvc pipe? "
Theoretically as you approach zero flow, the distance you can flow approaches infinity, so the practical limit is found when you know what minimum flowrate is acceptable to you. (While still recognizing that lower flowates can and will occur, at least until you get to the point where pipe discharge head equals the back pressure on the pipe outlet, if ever.

He just didn't say what value he considers "reasonable".

CVG,

The 50 psi you mention is the maximum pressure, when Q = 0 "stalled" condition. The pressure could be much less, almost 0 psig, if system Q is max at pump runout flow.

Artisi,

Might be OK, IF 5 gpm is inovermyhead's idea of THE "reasonable" flowrate.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[cvg]

actually, the 50 psi is with Q=0 and wind blowing at a moderate breeze. This would be the assumption if you installed a shutoff valve at the top of the well (which I don't recommend doing) and then closed it. The windmill would continue to spin and try to pump but since the valve is closed, it would generate pressure, but no flow. Eventually, either the windmill would stall completely or you would blow out the pump.

See link and attached file

http://www.engineeringtoolbox.com/positive-displacement-pumps-d_414.html

I'm not sure what a stuffing box is but you should be able to just run your pipe directly from the well to the tank. I really don't see an advantage to using gravity flow which would require an additional tank or standpipe at the windmill.

 

[BigInch]

As I see it, if you can use gravity flow, you can lift and store as much water in the nearby tank as possible at any given time, since there would not be any backpressure on the pump, ever. It would always lift as much water as possible to only the height of the tank level and thereby maximize flowrate for that head. Then with gravity flow, you just design that pipe for whatever flowrate you want to move to some other place. Gravity costs nothing to use and won't come with the potential to reduce your potential supply from the well at the expense of increasing the pipe inlet head to move more water farther away. In other words, never any pipe friction losses burned up by pump head.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[cvg]

there are several reasons why gravity flow would not be beneficial.

1) ground elevation at the windmill is 2 - 3 feet lower than at the site 500 feet away. since the two tanks would be hydraulically connected, water surface elevation in the two tanks will eualize and be nearly the same. This will result in a a) remote tank which will not fill to the top, or b) you have to excavate the remote tank 3 feet into the ground to install it or c)you need a taller tank at the windmill in order to completely fill the remote tank.

2) Head loss (back pressure on the pump) to convey the water to the remote tank is approximately the same regardless whether it is pumped or flows by gravity. Gravity does not move water without a differential in head. Approximately the same pumping energy is required either way. Since posative displacement pumps have a nearly vertical pump curve, pumping rate does not vary much with pressure (see the reference I attached previously).

3) Depending on the head differential in the two tanks and the pipe size, it might take quite a long time for the water to move to the remote tank. This would require significant capacity in the first tank.

3) Two tanks will require more capital expenditure and more O&M.


I guess the main benefit of two or more tanks is that you can store water in case the wind stops blowing.

 

[Artisi]

cvg

The point was to have the primary tank located next to the mill elevated well above the final discharge point so gravity flow could take place, also the primary tank only needs to be large enough to retain a theoretical maximun flow from the mill which exceeds the outflow - a function of available head in the tank /friction loss/flow rate.

 

[cvg]

artisi
elevating tank 1 so that it can flow into tank 2 is certainly an option. However, the pump still has to work just as hard to pump up to elevated tank 1 as it would to pump directly to the remote tank 2. And according to the OP, the pump has plenty of capacity to do it. So unless you need the extra volume of storage in two tanks, than what's the point of spending the extra money for two tanks?

 

[BigInch]

I think the true benefit of a totally unrestricted pump discharge is that usually where you find these applications the most important consideration is to have access to water, any water, and the maximum amount of water possible. At least that's how it was down in Laredo and here in Spain too.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Artisi]

BigInch - where is Don Quixote?

 

[BigInch]

He can be found in any Spanish bookstore.

Thought you were going to get me on that one, didn't you?

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/