4" @ 60 PSI Pelton / Induction Generator / Grid Tie HELP!!!

[carpentermikep]

I have been invited as a guest at a hunting lodge in Upstate New York, I'll be up there in a few weeks on a "work weekend" and I would like to try to sell the camp on investing in hydro power. Its a blue collar hunting camp and there are professional welders, plumbers, and electrical lineman in the membership ranks; each masters of their own trade.   

Most importantly... there is a heavy flowing spring, feeding a creek, ON THE LAND, that falls about 200' over 1500' of run.   

I would like to encourage the camp to generate grid tied power using a home made pelton setup.  Most of the members are older than me (31) and many years more experienced in their trades... so I want to iron out all the issues in my plan before I approach them.   

My plan....

I intend to manufacture a pelton wheel about 18" diameter with 16 spoons.  Each spoon will be two halves of 3" diameter iron pipe, about 4" long, cut length wise, and welded together to make a "number 3" profile shape.  Each of these will be welded to a 10" diameter center steel hub using 3/4 rebar.  The center hub will be housed inside of a 55 gallon drum, positioned horizontally with pillow blocks on either end to support the pelton wheel on a 1" axle.  I would like to have 8 - 1" nozzles to redirect the 4" of flow spaced equally around the drum.  Around the drum there would be alternating 4x2 sanitary PVC T's and 4" 45 degree PVC elbows forming an octagon of 4" pipe.  The 2" side of each 4x2 t's would then convert to 1" pvc nozzles, pointed towards the spoons inside the drum.  Each of the 8 - 1" nozzles should be backed by 60+ PSI of flow.

Down the hillside I would like to bury 4" HDPE corregated drainage pipe in 250' lengths.   Approximately 6 x 250 will leave me at the very least 120' of head.  The drainage pipe would be connected using standard HDPE connectors, each encased in a block of concrete.   I am hoping by burying the corregated pipe it will hold the necessary pressure.  The drop could be as much as a 200'; hard to say as you walk through the woods.  Anyway... at the bottom of the hill, near the creek, still on the hunting camp land is a power line and power pole, so grid tie would be really easy without too much wire expense.  At the top of the hill there would be a filter jenny to keep out debris.

Expected cost of the project is about $2000.

My questions:

1)  I would like to use a single phase 220v 1750 RPM 5HP motor.  Does this seem like the right size "induction generator" for my setup?

2)  Does anyone have any links to a specific schematic for hooking up an induction generator, running off a steady flowing pelton turbine, directly to the power grid?  Or, could you specifically describe all of the parts in question including any phase balancing relays, reverse power relays, start/stop relays, and breakers etc.

3) The mechanical ends of things I feel like the camp can handle... we can weld together a rock solid pelton wheel.  We can dig a trench and create a filter to divert 4" of clean water down the hillside.  We can do the 4" pipe to 8 x 1" nozzle plumbing; no problem.  We can install a 200 amp power pack on the pole, no problem.  I'm just not sure about SAFELY and LEGALLY connecting the "induction generator" to the live grid.  What would we be up against to actually turn the system on legally?

4) How much electricity do you expect we would be able to create with this system?

5) Please poke as many other holes in my plan as possible... (and then help me patch them up if please  ).

Thanks,

carpenter mike

[dbcollen]

I think you need to rethink a few aspects of this project

1) for 200 ft head and an 1800rpm induction motor you would need a 6 inch pitch diameter pelton runner. (44% vjet @ 86psi) this is not even taking pipe drop into account.
2) corrugated pipe will not hold the pressure you are talking about, think of using sch40 pvc. Corrugated pipe will have poor flow characteristics.
3) your nozzles for 4 inch pipe flow would need to be more like 4 @ 1/2 inch which would flow about 300 gpm @ 86 psi.
4) the more water you try to flow through a pipe, the less pressure you have at the nozzles.

How much water do you have available to you?
max power through a pipeline occurs at approx 1/3 pressure drop dynamic
 
Just preliminary numbers, guessing at 300 gpm and 200 ft static head gets you;
max power at 133 ft dynamic head, 5.25 inch runner for 1900rpm (4) 9/16 nozzles = 275 gpm and 6.75 KW available, actual power out of the induction setup would be about 2 KW @ 30% efficiency.

Dustin

[dbcollen]

Ran the pipe drop calcs, 1500 ft of sch40 4 inch will flow max power at 280 gpm (4)  9/16 nozzles would be close, and still about 2.0KW @ 30% efficiency.
Your estimate of $2000 seems really conservative, I would think with the permits that will be required, the project cost would exceed $10k.

Dustin

[hydrosun]

I agree with dustin, find out how much water you have available before making any other plans.
 Home made pelton spoons are a false economy. That is where your efficiency comes from. A properly designed system can go way over 50% efficient. You can buy low cost individual spoons to make different sized wheels. Check online, I don't remember the contact.
 I've seen an induction motor to grid intertie. It used a motor starter switch to connect the grid to the motor as the  water was turned on to speed up the turbine past the slip speed.  An electromagnet held up a weighted arm that connected to a deflector to block the water when the grid fails. It is manually lifted into place to start. This wasn't a legally sanctioned grid intertie so I don't know what would be required by your utility.
 I may be working on a system this year that will have all the approvals, but I'll have someone else design the controls and switching gear.
chris

[hydrosun]

The source for pelton spoons is h-hydro.com.  My low cost pipe of choice is gasketed sewer pipe with the joints glued. Last time I checked on 4 inch pipe it was running about $1.20/ foot. Although another system got pipe through his plumbing supply job for under $1/foot.
You also have to figure out an intake. I've been using coanda screen from hydroscreen.com with great success.
 A $2000 budget on a project of this size is very optimistic, unless you can scrounge a lot of the materials.
Chris

[XeonPony]

http://www.smallhydropower.com/induction.htm

http://www.qsl.net/ns8o/Induction_Generator.html

http://users.aber.ac.uk/iri/WIND/TECH/MISC/MotorsAsGenerators.html

Here are some great sites in reguards of how to size and convert induction motors to generators, there is one more site that was exceptional that is in the form of a pdf file:  http://www.redrok.com/cimtext.pdf

[carpentermikep]

thanks for your help!

>>>>I think you need to rethink a few aspects of this project
for 200 ft head and an 1800rpm induction motor you would need a 6 inch pitch diameter pelton runner. (44% vjet @ 86psi) this is not even taking pipe drop into account

I have checked at the hydro store and I've seen the spoons...  we have a member that crafts metal spiral staircases for a living, he says he can make spoons for us.   He was going to fabricate "pelton" type double well spoons.  What does "6 inch pitch" mean?  I'm a bit confused.  His raw material would be two halves of pipe, cut and welded using his magic.   His finished spoons were to be about 5 x 4, with a fin in the middle similar to the pelton design.  

>>>>corrugated pipe will not hold the pressure you are talking about, think of using sch40 pvc. Corrugated pipe will have poor flow characteristics.

Aren't we supposed to cut down the flow quite a bit at the nozzle; wouldn't that negate the need for high speed flow characteristics?  Also, the plumber on call at the lodge indicates that HDPE farm pipe (with the green line) from the local Tractor Supply Co. should hold at least 50 psi so long as its buried properly and the joints are cased in concrete.   The pipe is $105/250ft roll.  A real bargain... even if I can only use it for the first 750 feet of run because of pressure issues.   If it burst; we'll redo from that point on in PVC.    If we can keep it corrugated, that would be $600 expense in pipeline; good for budget.

>>>>your nozzles for 4 inch pipe flow would need to be more like 4 @ 1/2 inch which would flow about 300 gpm @ 86 psi.

so... if I'm using 4 at 1/2" nozzles... would that be the same as 8 @ 3/8 nozzle?  I like the 8 nozzle configuration I have drawn up and I understand that adding nozzles actual increases the power because there is more flow on each spoon.  I was hoping more nozzles would also overcome any hillbilly engineering in the spoon design.  My plan was to have it all go into 8 -1" as I said, because that was equal in area to the 4" pipe coming down.  I could see how adding a 1" x 3/8" pvc coupling at the end of each would act to create back pressure in the line; a nozzle.

>>How much water do you have available to you?

I could keep the 4" pipe wide open 365/year.

>>max power through a pipeline occurs at approx 1/3 pressure drop dynamic

so 4" pipe dropped down to 8 x 3/8 nozzles... would that achieve a 1/3 pressure drop?  I need help with this math.  Not sure what formulas you are using.

 
Just preliminary numbers, guessing at 300 gpm and 200 ft static head gets you;
max power at 133 ft dynamic head, 5.25 inch runner for 1900rpm (4) 9/16 nozzles = 275 gpm and 6.75 KW available, actual power out of the induction setup would be about 2 KW @ 30% efficiency.


2000 watts per hour / 24 hours per day ?  

or about...

20 cents per hour... $1752 per year.

hrmmm... the goal is more than that.  how can we maximize this number?  The goal is 10 Kwh.  What is the highest horsepower motor I could turn off of a 4" line with 200' head?

[carpentermikep]

The source for pelton spoons is h-hydro.com.  My low cost pipe of choice is gasketed sewer pipe with the joints glued. Last time I checked on 4 inch pipe it was running about $1.20/ foot. Although another system got pipe through his plumbing supply job for under $1/foot.
You also have to figure out an intake. I've been using coanda screen from hydroscreen.com with great success.
 A $2000 budget on a project of this size is very optimistic, unless you can scrounge a lot of the materials.
Chris

Thanks for the link.  I had already shown it to our steel worker.  I am hoping to use at least the beginning of the pipeline in corregated pipe... I have been assured it should hold up a good way down the hill without bursting; but we really had not considered putting nozzles on when I last talked.  The corregated pipe is under 45 cents per foot and I would really like to use it at least up top.  For the intake we were planning on using 300 feet of Slotted HDPE (about $150) in a medium gravel filled trench beginning a few hundred feed from the spring head.  It would give it a "sinking creek" effect.   I do think that many of the materials will be scrounged.  Like I said, its a blue collar hunting camp... many long years of collecting odds and ends from many different trades.  200 amp service... free, wires free, steel free.  motor, free.  The only real cost is specialty breakers and relays and pipe cost to get down the hill and wrapped around a turbine.   

[dbcollen]

the most power you will be able to get from 1500 ft of 4 inch smooth pipe will occur at 280 gpm, if you try to use more water the power will be less.
The pipe is capable of flowing more water, but the losses due to friction in the pipe will be greater, reducing the power available. If everything was working at 100% efficiency in an ideal world, the1500 ft long 4 inch smooth wall pipe can only provide 6.67KW PERIOD, what you will see out after the losses from the pelton runner and the induction generator will be a fraction of that. Sorry, I didn't write the laws of physics, and nobody has figured out a way to break them.

Dustin

[carpentermikep]

Fair enough... where would I be if we upgraded to 6" pipe?   There is plenty enough water on the land.  Near the spring head, there are actually 4 springs, each capable of filling a 4" pipe full bore, they all empty into a pond and the pond currently overflows into a creek, but a 6" line could be stuck into pond fairly easily and still get us 120' of head without getting off of the property.  Could we get closer to that 10kwh mark? 

I appreciate the pragmaticism of your advice.  I feel like I am on a rapid learning curve.  I really want to iron out a concrete plan before presenting to the lodge.

With a 4" setup setup, is a 5hp 3 phase 1750 motor the best choice?  What about a 6" setup... would a 10hp 3 phase 1750 be best? 

I am now seeing 6" corrugated pipe traveling about 1500' from the pond with about 120' of head.  It would convert into a 4" octagon loop with 8 nozzles... each 1/2"  spraying onto 6" diameter spoons.  (watching the budget climb... )  Upgrading from 1500 feet of 4" to 1500 feet of 6" will raise the pipeline budget from $650 to close to $2000. 

Also, how are you calculating all of these numbers (ie max power at 280 gpm, size of nozzles, 6.67kwh, etc.)?  Are there charts or do you have some kind of java applet you could point me to?

thanks again,

Mike

[XeonPony]

My main idea for power for my self is 400w, for every horse power of the motor you can only get about 45% of the power, so for 400 watts I selected a 1.5Hp induction motor, for a good safety factor and keeping my ballast capacitor bank small.

So that was my logic, I hope it will help you.

[carpentermikep]

My main idea for power for my self is 400w, for every horse power of the motor you can only get about 45% of the power, so for 400 watts I selected a 1.5Hp induction motor, for a good safety factor and keeping my ballast capacitor bank small.

So that was my logic, I hope it will help you.

ok... so as I recall... 1 HP = 745 watts.  But you're saying working as an induction generator setup, I only get 45% capacity.   so...

1 x .45 x 745 = 335 watts

you chose a 1.5 x .45 x 750 = 502 ; but you're calling it 400? 

None the less... lets stick with this logic. 

I'm after 10,000 watts... so:

10000 / 750 / .45 = 29.6

I would need a 30 hp motor to generate 10kwh of power?

yikes...

I don't expect even 6" of flow at 60 psi is going to turn that.  Am I wrong?  I was thinking it would be able to push about a 10 hp motor.

[hydrosun]

Argh, I spent a bunch of time last night answering all these questions and the posting just dissapeared.  I have charts in a, hydro design catalog that I got 20 years ago, for nozzle flow, pressure drops and rpm of different diameter peltons. Some of the info is available online, but I don't have the links at hand.

One key thing you need to understand is that a pipe of a certain diameter can carry more water the smoother the inner surface. For instance a pvc pipe has half the pressure loss as a similar sized steel pipe. On a corregated pipe there will be swirls and back eddies slowing down the water. The only way I can estimate the pressure drop is to discount the outside 1/2 inch as stalled water and use the inner full flow to calculate the size of the pipe. So a 4 inch pipe might be comparable to a 3 inch and a 6 inch comparable to a 5 inch. Someone else might have a better solution using the degree of roughness in the formula to calculate the pressure drop.  Pressure drop on a 5 inch pipe is about 50% higher than 6 inch. to get a rough idea of the relations between pipe sizes I like to square the diameter. so a 4 inch pipe is 16, 5 inch is 25, 6 inch is 36. Those numbers give a quick indication of the proportions between pipe sizes. Cross section formula involving pi is the same for all.

The charts show head loss in feet for a hundred feet of pipe at different flows.`A 6 inch pvc pipe running 300 gpm loses less than 10 feet head in 1500 feet. So your 200 feet static becomes 190 feet. The power at 50% efficiency is 5700watts. Running 600gpm would lose about 35 feet, so 165 feet head and 600 gpm is about 9900 watts. A 6 inch pelton  would spin about 1850 rpm at this head. A little slow for a 1800 rpm induction motor plus slip. The efficiency would suffer a bit.   I think the largest size nozzle that can be used on a 6 inch pelton is a 1 inch nozzle. A 1 inch nozzle at 165 head will let out about 250 gpm. More than two nozzles on a turbine will interfere with the free flow of water out of the spoons and cause a loss of power. To avoid that you could put two pelton wheels side by side on the same shaft. Two 1 inch and a 5/8 would get you close  to the 600 gpm.  
A 6 inch pelton has the jet of water hitting the spoons 6 inches from the center of the shaft. That determines the rpm at different heads. The closer to the center the higher the rpm. Just like shorter blades on a wind generator. By matching the turbine rpm with motor rpm plus 10% slippage you can direct couple without the losses of pulleys and belts.  Everytime the gpm increases the pressure drop increased and lowers the rpm. so you lose power in the pipe and power in getting out of the most efficient transfer of energy from water to wheel.

You still need to get an accurate number for gpm water flow. Full flow of a pipe depends on the speed of the water. It's critical that you get that info before you put in anything. All the calculations depend on that.
Chris

[XeonPony]

well the 40% I gave was to ensure a high level of safety factor for surge loads, remember that when using an induction motor as a generator driving other inductive loads tends to mess things up in the sense of noise and possible colaps of the generators field requiring a restart of the system.

[dbcollen]

Power out is really dependent on the motor, some are better than others, I am running a cap excited 1hp 3ph 1200rpm motor at 100hz loaded, and getting 1500 watts from it, used for battery charging.  Being grid connected and having the grid supply the VARs for the field, I would imagine you could get the Full load Amp rating from the motor, (around 1kw per Hp) Your limitation will be motor heating, not lack of field, as the field is supplied by the grid. Do not use any capacitors for power factor correction, because it will cause the motor to self excite and has the potential to make an "island". As long as your section of grid has a lagging power factor the motor cannot self excite if the grid goes down.

Dustin

[rotty]

Your requirements are similar to my system.
I have 1800' with a 60 foot drop (28 psi).
I suggest you go with 6" pipe sch40 pipe  (smooth  wall) and use long radius turns  or the largest pipe you can afford.
I also suggest your do some type of survey (use a weir) as the the year around water capabilities of the stream.

Try this link http://www.h-hydro.com/
He has turgo wheels with spoons. I also suggest you down load his spread sheets and run the numbers. This way you can try many different senarios and only burn electrons instead of money.
I would also not connect to the grid, otherwise lots of redtape and permits.

According to the spread sheets,
with a 4" sch 40 pipe you could get a max ~5200 watts, two jets at 0.819 dia (300gpm) and a 5.87" diameter turgo wheel for ~ 1900rpm full load
with a 6" max power is > 14kw at 2 jets 1.375" (850 gpm)and a 5.48" dia turgo. As you can see the bigger the pipe with less friction loss, your available power goes up drastically.

I believe your cost are going to be more than 2k$ for pipe. I would suspect closer to 2$ a foot and that is surplus/good scrounger.

Are you planning on a frequency controlled system? Then add the cost for a controller. I would oversize the motor so it does not over heat/stress it.
5200watts is ~7 hp at 100% efficient, which it is not. The best you could hope for is ~ 50% system efficiency from water power to electrical power.
I am not trying to discourage your but help with realistic expectations.

Also you may want to think about some how to filter the water so you do not clog your jets, and maintanence of the system.

I wish I had your water drop so I could have more power.
If you have any questions, PM me.

[Vtbsr]

Hi, carpentermikep. I would not go with the grid tie. Try to get 100 ft head. This should be enough power with out the total penstock you wanted to run with the corrigated . That pipe can crush and might plug up with the rough surface inside. Run srd 35 the green gasketed pvc pipe. I would run a Harris type pelton about 5 inch dia wheel. Use the one with adjustable field strength. For nozzles, 1-   1/2 inch, 1-    3/8  inch, 2-   1/4 inch.  Run the DC into 8 Trojen L-16 battieries set up for 48 volt, and inverter xw xantrex.  Since this is a camp you won't need much power when no one is there during the week. The bat bank will carry the wide loads that will turn on and off when people are there. You will need a  120 gallon water tank for the diversion load. When the power is not being used the excess will run through a c-40 and into a 1500 watt element in the tank. You get the extra of, free hot water. This system should work with out, a lot of problems.  I  know of a fellow that had a grid tie system. The grid turned the motor and if it over speed the power would flow back to the grid. His intake plugged and the system ran like a motor for days before he noticed. How is the lodge set up right now? Do you have LP gas ect. Good luck

[hydrosun]

The appeal of doing it offgrid is the possibility of getting it done quickly without going through  the permit process. Dustin mentioned the cost of permits, but the delays may be more important.  I've done many small offgrid hydro systems quietly. Just finished one yesterday as part of an SEI class.
 I looked at one potential grid tie system that the owner spent 10 years getting all the approvals. At that point he was older and no longer interested in putting in the system. I've no idea how long your permit process would be. On one system I've done some design, the owner is expected to try to navigate the permit process. When the utility is involved, it would be impossible to avoid all the paperwork, and permit fees. Even if all the water flow is on your property.
Using one Harris would limit your output to about 1000 to 1500 watts depending on the head you choose to use.
The other side of an off grid system is identifying the loads that would be run by the system. On grid you just offset some or all of your power use.
So sizing an offgrid system to your needs wouldn't be as simple a system as grid tie, but might be an quicker project for a do-it-yourself.
If you decide to go that route I can provide more info on designing the system.
Chris