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Renewable Energy Questions/Discussion => Solar (heating or electric) => Topic started by: eraser3000 on October 20, 2016, 11:20:46 pm

Title: New Electric Booster Boiler
Post by: eraser3000 on October 20, 2016, 11:20:46 pm
Will be 20KW using 20 - 1KW Elements
The reason for this is for finer control and less of a hit on inverters.
Its easier on inverters to PWM an SSR on a small element than it is on a larger one.

So Im going to use SSRs on all these elements and build a custom PID control to control them.

Elements are Tempco 1000w - 480volt single phase elements.  Threads are 1/2 NPT.

I started by taping a piece of string in a spiral around the piece of 6" tubing.

I then marked and drilled all of the holes progressing from 1/8" to 5/8".
Then I cut 1/2" heavy wall couplings and cut off a small portion with about 6 threads.
Then I TIG welded them on around the spiral.

[attachimg=4]
[attachimg=3]
[attachimg=1]
[attachimg=2]
[attachimg=5]


Title: Re: New Electric Booster Boiler
Post by: bj on October 21, 2016, 06:13:13 am
  Nice work.  Tig is the best way on something like that.
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 24, 2016, 11:05:14 pm
Thanks BJ, I really enjoy TIG welding can't say that about stick or MIG.
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 24, 2016, 11:18:04 pm
I finally got around to the Plasma table and cut out the top and bottom.
[attachimg=1]
I roughed a quick sketch in Fusion 360 and had some quick and dirty G-Code.
[attachimg=6]

(Contour1)
N20 M36 T6
(Through cutting)

N25 G0 X4.37 Y-0.0722
(TURN ON CUTTING)
N30 M7
(POINT-PIERCE)
N35 G4 X5.
N40 G1 Y-0.4122 F40
N45 G3 X4.62 Y-0.6622 I0.25
N50 Y0.6578 J0.66
N55 Y-0.6622 J-0.66
N60 X4.87 Y-0.4122 J0.25
N65 G1 Y-0.0722
(TURN OFF CUTTING)
N70 M8
N75 G0 X0.3845 Y-2.3183
(TURN ON CUTTING)
N80 M7
etc.................


Here the top placed.
[attachimg=2]

Then I cut and chamfered 1" heavy wall couplings.
[attachimg=3]

Then I welded them inside and out.
[attachimg=4]

And now lid is on, time for grinding and painting.
[attachimg=5]
Title: Re: New Electric Booster Boiler
Post by: DJ on October 25, 2016, 03:51:40 am

So what is the setup of this going to be?
Are you going to use it like an instant on demand heater or have it going to a storage tank?
Are you going to run all 20 elements at once or modulate them depending on available power at the time?

With 20Kw available, the water even with 1" flow is sure going to get a decent heat rise in a single pass. 

I have been playing with a modified gas water heater. Took the gas ring out and fire it with a modified waste oil burner.  I can sink about 20Kw into that without too much inefficiency in flames blowing right out the top.  I'd like to get a 400L tank. That way I could fire the thing every 2-3 days and be able to drop more heat in as well.

I'm trying to work out more about the controllers you linked to. I still don't fully understand their capabilities as I know nothing about them but I'll keep researching. they would seem to be ideal for controlling something like a burner and having some safety devices built in as well.
Title: Re: New Electric Booster Boiler
Post by: bj on October 25, 2016, 06:57:56 am
  Totally agree on Tig.  Mig has it's uses, but have never bothered to own a machine.
  Great project,  turning out nice.
 
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 25, 2016, 08:44:24 am
On a side note the TIG welder power consumption was around 3500 watts during welding.
Title: Re: New Electric Booster Boiler
Post by: rossw on October 25, 2016, 09:29:56 am
With 20Kw available, the water even with 1" flow is sure going to get a decent heat rise in a single pass. 

By my calculations - a very modest 15 litres/minute flow will only heat water by 19 degrees C at that power.
Even if it was running at full power with only 5 litres/minute flow the temperature rise is just over 57 deg C.

Yes, it's decent - but it's fairly easily managed.
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 25, 2016, 09:31:16 am
DJ:
I am going to modulate them.
So if turbine output is 580watts only 1 element will be PWM and using a AC RMS current sensor for the feedback I'll let the PID controller do its thing. If wind output is 13500watts then 13 elements will be fully on and element 14 will be 50% on.

I am hoping for a good rise in one pass and plan to flow 10 gallons per minute through it.

I currently have about 1200 gallons of storage tank in the room and have another room with much larger tanks to be plumbed in at a later time.
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 25, 2016, 10:19:39 am

I have been playing with a modified gas water heater. Took the gas ring out and fire it with a modified waste oil burner.  I can sink about 20Kw into that without too much inefficiency in flames blowing right out the top.  I'd like to get a 400L tank. That way I could fire the thing every 2-3 days and be able to drop more heat in as well.

I'm trying to work out more about the controllers you linked to. I still don't fully understand their capabilities as I know nothing about them but I'll keep researching. they would seem to be ideal for controlling something like a burner and having some safety devices built in as well.

Sounds like a great project would love to see some pictures .
If you need a hand with the controller end of it let me know.
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 25, 2016, 10:23:29 am
Thanks Ross

With 20Kw available, the water even with 1" flow is sure going to get a decent heat rise in a single pass. 

By my calculations - a very modest 15 litres/minute flow will only heat water by 19 degrees C at that power.
Even if it was running at full power with only 5 litres/minute flow the temperature rise is just over 57 deg C.

Yes, it's decent - but it's fairly easily managed.
Title: Re: New Electric Booster Boiler
Post by: DJ on October 25, 2016, 10:19:37 pm
With 20Kw available, the water even with 1" flow is sure going to get a decent heat rise in a single pass. 

By my calculations - a very modest 15 litres/minute flow will only heat water by 19 degrees C at that power.
Even if it was running at full power with only 5 litres/minute flow the temperature rise is just over 57 deg C.


Summer water temps here straight out the tap can easily be above 20o. add another 19 and you are well at shower temps.  Would be a good shower at 15l min. New and upgraded plumbing here is mandated to be limited to 50o so if you backed the flow down to 10L min, youd be very close I'd say.

5L min which is more on the mark for the hot water side would be way too hot at 57 and would need to be mixed with cold to give you a reasonable temp and would be perfectly adequate as an instant heater.

Given the power of most storage heaters and that I have never seen a single phase instant heater do that sort of output, I'd still say it's a decent heat rise in one pass!  :0)


Quote
I currently have about 1200 gallons of storage tank in the room and have another room with much larger tanks to be plumbed in at a later time.

Why SO much hot water?  Are you using it to space heat as well?
You keep throwing out figures that would better suit a hotel than a home.
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 25, 2016, 10:55:29 pm
Painted
[attachimg=1]

I added a little 90 in there for support since the whole thing will be supported just by the 1" pipe.
[attachimg=2]

Booster Boiler is going to be added on top of existing boiler.
This boiler takes the excess split phase 240 from the Solar String inverters. From another post.
http://www.anotherpower.com/board/index.php/topic,1203.0.html
[attachimg=3]

1200 Gallon Tank Insulated and wrapped.
[attachimg=4]

A couple manifolds the tank feeds.
[attachimg=5]
[attachimg=6]

DJ, Boiler system needs to be big to support the place here, I have a lot of square footage and it gets very cold in the winter.

My evacuated tube system also feeds the tanks.
http://www.anotherpower.com/board/index.php/topic,1198.0.html
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 26, 2016, 10:32:09 pm
Well it holds air!
[attachimg=1]
Title: Re: New Electric Booster Boiler
Post by: oztules on October 27, 2016, 12:41:00 am
A sobering thought on direct heating of water.
I was working on a rheem instant hot water unit, and noticed the nameplate stated that it uses over 55kw for the 25lpm model for 25C temp increase.... it is not easy stuff.

..........oztules
Title: Re: New Electric Booster Boiler
Post by: rossw on October 27, 2016, 01:03:17 am
I was working on a rheem instant hot water unit, and noticed the nameplate stated that it uses over 55kw for the 25lpm model for 25C temp increase.... it is not easy stuff.

17:00:28-27/10/16| [RossW]   !kwheat 55 25
17:00:28-27/10/16| -RossBot- 55.00 Kilowatts input will heat water at 25.00 litres/min by 31.55 deg C

I wonder what their losses are... or if they're leaving some "wiggle room"?
(45kW should manage 25.8 deg C rise)
Title: Re: New Electric Booster Boiler
Post by: oztules on October 27, 2016, 03:48:23 am
This is not a calorimeter.... it's a gas hot water  unit, and as such has burning hot gas pouring out the top exhaust... I'm guessing this is where it is.
 To heat on the run we need a big delta T or a long time of interface between the "heat source and the heated material".

As we are heating water running past quite quickly before it exits the heat zone, we need a big differential to transfer the heat across the barrier quickly.... and so any of the gas still hotter than the water is lost energy... and there is a truck load of that pouring out the exhaust.

Incomplete burning due to excess gas compared to the  storchiometry, ie being a bit rich to keep it burning nicely, but still hot means a slight smell of gas in the exhaust. It has a 3 stage burner system to allow for throttling, and this won't help either, as the flame bed is not always complete at the lower regions... ie being a low pressure system, the flow rate suffers when all three flame beds are active.... so they need to be a bit rich in the "slower" range, so they lean off, but are still effective when the three fire up all together on the same gas stream... clutching at straws now......

The safety system includes a forcing fan, which will also cause the flame heat to be air cooled and scattered about. I think it is there to scavenge any excess gas out of the units, and stopping heat spots near the flame areas and casing.

Sound convincing???.. I have run out of ideas now....


...........oztules
Title: Re: New Electric Booster Boiler
Post by: rossw on October 27, 2016, 05:40:07 am
This is not a calorimeter.... it's a gas hot water  unit, and as such has burning hot gas pouring out the top exhaust...

Ahh, yes, and that perfectly explains the difference. (For reasons unknown, I thought you'd found an electric one - most of the ones I've seen are rated in MJ, not kW)

(Part of the reason most gas burners *NEED* hot flue gas is because of the sulfur (SO2)  disolves in the water vapor and forms sulfuric acid which eats out the heat exchanger, flue etc. (I wonder if the various nitrogen oxides (NOx) form nitric acid too?))

Title: Re: New Electric Booster Boiler
Post by: oztules on October 27, 2016, 02:05:27 pm
odd...
"Ahh, yes, and that perfectly explains the difference. (For reasons unknown, I thought you'd found an electric one - most of the ones I've seen are rated in MJ, not kW)"

It's taken 10 years to see you fluff your lines like this.... so I'm gonna make the most of it, as I know it won't happen again :) :) :) :)


 MJ is a measure of energy, which is pointless in a lpm temp change calculation. It's equivalence would be kwh... which tells us nothing about how fast we can heat how much water..... only that we have energy available to heat an unknown amount of water an unknown amount of degrees above perhaps ambient T... so there would have to be a time base there as well such as MJ/H ..... ie the difference between a mars bar and a hand grenade... similar energy, different power outcomes. :)

Actually we have propane, (LPG not LNG) here, so really only CO2 and H2O.... energy for bond dissociation of N2 is probably not there except for minuscule conversions.... it is not like the temp and pressure available in an engine (  otto cycle) environment.

The sulphur is also not in the fuel persay, but there will be  tiny amounts because of the perfume they add ( C2H5SH) ethyl mercapton  ( stench gas)... so we have essentially   C3H8 only. The N2 bond is one of the strongest bonds in chemistry, so unlikely to be broken in this sort of reaction... add shock and pressure to the heat, and I suspect a different outcome.... but not at 1atm.   Stench gas is toxic, but at the concentrations ( tiny) they use is harmless.

We can thank vultures for this... it was noticed that vultures would circle around areas that had gas leaks in the early natural gas lines in USA, and so they realised it was a useful thing to add to LPG as an indicator too... and they increased it in the natural gas where it was lower ppm in some gas reserves. It occurs naturally in natural gas apparently.

I have completely and totally used up all my  smartarsedness  with your energy-power snafu.....so it boils down to this.... .

It is still a big whack of power in a little box... just for a shower......





.............oztules
Title: Re: New Electric Booster Boiler
Post by: DJ on October 27, 2016, 05:53:14 pm
A sobering thought on direct heating of water.
I was working on a rheem instant hot water unit, and noticed the nameplate stated that it uses over 55kw for the 25lpm model for 25C temp increase.... it is not easy stuff.

..........oztules

Water heating takes immense amounts of power as you point out.  This is why I have gone with using a waste oil burner.
I have the heat exchanger from  gas heater that was used in an Olympic pool. It's rated at 200 Kw and my burners can over power it easily. I also have a smaller spa heater and a water heater I have converted.

The water heater is only a small one at 125L but once I get it up to heat, the thing will run as continuous basically.  The kids have tried to run it out but I can run it hard enough that it will keep up with demand.  Just have to watch when they are finished and get out that it does not over heat before the next one gets in.  I'm looking at controls to fix that problem.

The thing works so well I have plumbed it into the house ht water circuit.  I have valves so I can Feed from the electric or the oil burner Heater.
I'm on the lookout for a 400L unit to convert. With this I would only need to do a fire up every 2-3 days on what we use on average.  I would set this up as a feed for the electric heater.  Even if the Oil powered heater was a bit cool, it could be feeding water at say 40o to the electric heater instead of say 15o therefore making the electric heat up faster and cost less.

I have a 70Kl Swimming pool and I can heat that from winter temps to 35+ in 24 Hours.  Takes a 44 gallon drum full of oil and a bit more But it's awesome to have a pool party in winter that's for sure.
I was going to use the pool as my thermal storage for home heating but I have been looking at moving for some time so haven't bothered setting that up.
I did use another 125 L heater this year this winter for home heating.  Had the burner going controlled by a fuel pump on a timer that just pumped for 2 sec then switched off for 4 and circulated the water with a small electric pump.  The high tech heat exchanger was a car radiator with an electric fan.
The system worked really well and we were very cosy but it needed refining.

My house is basically a front and back area with a door between, the back could be too warm and the front too cold. It really needed another radiator in the front section or what I was thinking would be even better, Run the existing radiator into the house and after that have another Under the quite well sealed floor area to allow the whole place to heat up.

Again looking to move so not worth the effort here but the wife has been encouraging me to do it anyway for Summer.
We had a very warm day ( or what seemed like it) a few weeks ago.  I just pumped water directly from the pool  through the radiator and it made for very effective poor mans AC.  I figure the pool will always be cooler than the ambient summer temps and It might be effective to spray the return water to cool it or blow a fan over the top at night.

Evaporation isn't an issue, I put some IBC's Under the downpipes years ago and with the summer rains always have more than enough water to offset the evaporation that occurs. Often one good rain shower overfills the pool level on it's own and theres really no problem with running it a bit low. I have a lot of margin between high and low to play with.
The Mrs wants me to put the Radiator in the front section of the house so we can have the bedrooms Cool to sleep  at night. The front AC broke so no point replacing that now, plus we never liked it on while we were sleeping as it always gave us Chills no matter where we set it.

Not that I'm worried, but it also is a lot less power to run a 300W pump than an AC unit.

The other unit I have is a spa size heater rated at 100Kw which will be plenty of over kill for the home heating and has the various sensors from the gas burner control that I can tap into to control the oil burner.  At this stage I see it as basicaly a constant burn system with safety  cutouts but even a high and low burn rate would make the thing entirely practical.  I could set the low burn under what I normally need and the high above and just have a thermostat switch between the 2 as needed.

That's the great thing with my burners.  Commercial units seem to have about a 4:1 turn down ratio. I have read of some Gas units with a 10: turndown ratio. I can get a 50:1+ on my oil burners without much trouble at all. Anything from a Litre an hour to a litre a Minute on the same burner.  If I had the thing idling at 10 KW and burning at 40, That would be all I'd need and just cycle between the 2.

The other option of course depending on where we end up,  is to just Co gen my Lister engine and make heat with that and tap off the power as a side benefit which is really the best way to look at those sort of setups. 
Title: Re: New Electric Booster Boiler
Post by: rossw on October 27, 2016, 06:13:13 pm
It's taken 10 years to see you fluff your lines like this.... so I'm gonna make the most of it

It's a fair cop! Yes, of course I "meant" MJ/H but it's not what I said - well picked :)



Quote
Actually we have propane, (LPG not LNG) here, so really only CO2 and H2O....

Same here, and probably explains why I see far far less issue than we did at our old place, which had town-gas (LNG). The old pool heater (gas) rusted up in very short order.


Quote
We can thank vultures for this... it was noticed that vultures would circle around areas that had gas leaks

Well there you go, I've learned something :)

Quote
It is still a big whack of power in a little box... just for a shower......

Absolutely :)




.............oztules
[/quote]
Title: Re: New Electric Booster Boiler
Post by: rossw on October 27, 2016, 06:22:22 pm
I'm on the lookout for a 400L unit to convert. With this I would only need to do a fire up every 2-3 days on what we use on average.

I have two, 2000 litre tanks. They are heated by whatever "available heat" we have. A 60-tube evac tube solar collector feeds directly to one. The generator (complete with exhaust heat recovery) and the 50kW wood-fired boiler both heat both tanks (via heat-exchangers in the bottom).

You'll want to super-insulate your tanks. We seem to lose a fair bit of heat - even if you use almost none, if we don't add heat at all, we only get about 4 days storage of water hot enough for normal domestic use. (I'll just add in here - that we don't actually store any "hot" potable water. Our domestic "hot" water is the domestic "cold" water passed through a copper coil in the top of each storage tank).

Title: Re: New Electric Booster Boiler
Post by: DJ on October 27, 2016, 11:30:56 pm

The tanks I was referring to were actually gas hot water heaters which will already be Insulated... to a point anyway.

I see a gross inefficiency in them being the tube that runs through the centre where the flame/ vent normally is.  On my 125 heater, you can feel the thermo siphon effect once the flame is off with the air being drawn through  which would be a heat loss. I have read that is significant which I don't doubt for a second and also that the pilot light normally running when they are on gas is a significant amount of energy a day that compensates.

I was thinking I would need some sort of Solenoid operated shutter on the top of the flue for this to seal off the vent and stop/ significantly slow the draft losses.

I did think about insulating regular IBC tanks.  Do you think a layer or 2 of house fibreglass roof batts would be sufficient? I guess there is going to be a point where the heat loss happens no matter what you do. The thing would be to get as neat that as cost effectively as possible.

I have been looking at the evacuated tubes as well. Here they are not economical compared to used PV I can backfeed and use a normal cheap heating element but I am interested in them none the less.  What I can't seem to find is any sort of specification on their output.
Panels are all rated so I know how much power they produce but I can't seem to find anything that tells me what a Tube does.

All I have found is something that says the output of a 10 tube collector is equal to 648W. this is bugger all and seems to conflict with my other belief from what I have read that these things are super effective at heating water.  Is there something else at play here? The same article said a 30 Tube collector had a 2Kw output.  Given the cost of that and the cost of even a new installed PV system, there has to be something else or why would you even think of Tubes for water heating?

At least with PV, once the water is up to temp the power can go to other things. With Tubes it just does nothing..... which is something else I can't figure, how does the thing shutdown or stop heating once the water is up to temp or do you get 150o Water at 30PSI in the right conditions?
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 28, 2016, 08:55:40 am
The specifications on mine show differently:
Category(Ti-Ta),  Clear Day 2000Btu/ft2/day,  Mildly Cloudy 1500 Btu/ft2/day,  Cloudy Day 1000 Btu/ft2/day
A (-9F) 47,000 36,000 24,000
B (9F) 46,000 34,000 22,000
C (36F) 43,000 31,000 19,000
D (90F) 36,000 25,000 13,000
E (144F) 29,000 18,000 7,000

(Ti) – Temperature Inlet: Refers to temperature of fluid entering manifold.
(Ta) – Temperature Ambient: Refers to the ambient temperature, or the outside air temperature.
(Ti-Ta) – Refers to the inlet fluid temperature subtracted from the outside ambient temperature. For example, if the temperature
entering the manifold is 100F, and the outside air temperature is 80F, the Ti-Ta would be 20F.

http://www.solarpanelsplus.com/pdfs/spec-sheet-spp-30a-revb.pdf

From experience I think that is pretty accurate.  I am normally in the D Category.  So for me 36K btu each is great. That 10.5 KW.  It really starts adding up when you have several in series as you can get huge deltas at fairly substantial flow rates.




Title: Re: New Electric Booster Boiler
Post by: eraser3000 on October 30, 2016, 06:38:30 pm
A little more progress.

[attachimg=1]
Title: Re: New Electric Booster Boiler
Post by: bj on October 31, 2016, 06:25:39 am
  Looking great.
Title: Re: New Electric Booster Boiler
Post by: eraser3000 on November 17, 2016, 09:43:29 am
Looks like spaghetti.
[attachimg=1]
But its functional.  Next step will be to clean it up and insulate a little more.
[attachimg=2]
Handles a load nicely.
[attachimg=3]
Title: Re: New Electric Booster Boiler
Post by: bj on November 18, 2016, 06:55:12 am
  Functional has to be first, otherwise continuing would be fruitless.  ;)
  Coming along nicely.  Very interesting project.