Anyone Doing Co gen or alternative home heating?

[hca]

I have looked for ideas to move from electric heat in the boiler to an alternative, one is LPG which is easy to control, the other was wood, but on looking at you project I see waste oil is an option I had not thought about. As it works out here I figure LPG to cost the same as electric which leaves oil or wood as the fuel. Just as you need a way to get the heat output in the house, I need a way to get it in the boiler likewise in a controlled manner, I am not to keen on the idea of open flame under the reflux stack and the risks that entails as the product is 93% not 40ish like normal pot setup.

About 50 years ago we had a diesel fired boiler at home, I am sure your familiar with the blower system they use, it worked by venting the exhaust through exchange tubes the water tank, that's one way I could do it, another is via a fluid heat exchanger with water or super heated steam or maybe pump the mash through it.. Obviously it has to be properly built.

That boiler fed a layer of poly pipes in the concrete stab, a loop for every room on valve manifold. No cold bathroom floors, it was a very good and flexible system for the day.

But I need to be controlled in a linear manner,if using the exhaust a splitter vane driven with a positioner jack would suffice but there is the soot build up creating an insulating barrier. With a fluid transfer probably a speed controlled high temperature pump would be needed. So I have been mulling over ideas to measure and control an open flame heat source.

With the current setup I started with 2 Omron timers driving a contactor on the element supply giving adjustable pulse with as rate on the heat, but it was noisy and difficult to optimise as the volatile content of the pot boils away. I looked at what others were building on distilling forums, they were using cheap on/off SSRs with an adjustment on the rate. They all bang on about safety with the risk of fire, scalding and burns, but then use a common pot with 240volts on it and say a sparkie should wire it up. Not to keen on a sparkie who would. Some were using a pid controller which was at least safe.

So not yet retired I lashed out on PTC sensors, pid controllers and a current loop controllers linear SSR which gave good linear control and replaced all of the thermometers on the reflux stack. It was an epiphany, I could see the temps of everything inside the system, tweak the heating input and reflux control cooler and I over time really learnt how to understand and drive it to produce top quality product with minimal waste. Buy using pid controllers to replace all the thermometers with panel laid out like the machine made easy reading from a distance and each one had 2 set points outputs to drive an indicator.

I looked in to PLCs, all the big name ones were coming as OEM from a factory in China who had their own model for much cheaper and the software ware free. I had already made sure the PIDs all had modbus. So PLCs led me to look into SCADA, but it also was expensive software although it could also be used to look after a lot of other things around the place here. However the more you add to a PLC system the more expensive it gets.

In the end I found a 30EU SCADA program that runs in a raspi from a company that sell big system PC SCADA software, it had modbus and could use the raspi io, its stand alone so you can access everything on a web browser from your phone even. Also I found cheap arduinos could be made into modbus out stations connected via network and RS482 and no limit on the sensors available. We have terrifying up close lightning strikes here in the rainy season so inter building network is fibre for isolation, control via network means the copper cables are not needed thus maintaining isolation.

More recently one of the kids has been on about starting a micro distillery and wants me to build him the system which is a whole new ball game to my occasional use hobby machine. That's what brings be back to thinking about a cost efficient flame fired boiler and your project.

[george65]

Very interesting Info there.

I think hot water would be the way to go. It would not be hard to set up an arduino on a thermo couple to drive a solenoid valve so a very accurate temp could be maintained by regulating the water flow. Have you any idea of how much heat input you would want? I imagine after the mash was up to temp it wouldn't take much to keep it there.

Last couple of days I have ran some consumption tests and seems the burner is running very near if not 5Kw. I have been using a 3L Milk jug as a fuel tank it's it's lasted near as either way to 3 hours for 4 runs now. I have got the thing pretty dialed in on the pump at 1 sec on, 25 sec off. I did the extra holes in the burner and much to my surprise, It didn't clean up the burn a whole lot at all. In fact, I think it may have made it worse depending on how hot the burner is running. Yesterday it seemed pretty dirty but today seemed to clean up. I remember when I played with draft burners years ago I could never get them to run completely clean which was why I went to forced air burners. I can get them in any size to run with barely ash in the burner or the flue let alone soot. I also noticed that adding more secondary holes reduced the draft on the burner primary air inlet which is logical.
Despite the not clean running, I pulled out the diffuser plate this morning and was surprised to see it was completely clean on the bottom and just had a little soot on the top. It's probably running hot enough in the flame path to self clean. Once a metal gets near dull red the carbon will burn which is around 600oC .

Given I have got this one at 5 Kw with no trouble and primarily by limiting the draft naturally through the heater, I'm thinking a 2 Kw burner may be a lot more doable than I thought. Just reduce the size of the setup to limit heat loss and limit the draft which would also keep the thing hot and should be fine. I think rather than restricting the Flue, the way to go would be with the secondary air holes to limit the draw but provide plenty of air for complete combustion. I have had this thing running since before lunch today and haven't really had to touch it. It's running very close if not at an accurate 5KW burn bit With losses, I think I'd like more heat now. I think the limiting factor is the water tank itself. I tried blowing more air in the primary air hole and all that did was make the thing smoke more. Maybe forced air in the secondarys would be the way to go?

The other thing I'm thinking for more power is get an old car gas tank or 2 and weld a larger flue right through the middle. I could weld in some bolts through the sides before I put it together for greater gas disruption and heat transfer. I was also thinking a tube through the back of the burner itself through the flame front may pick up a bit of useful heat as well given how hot the now suspended legs on the thing are. I have the water heater on a stand with the burner held up tight underneath with an old car scissor jack. Crude but plenty effective.

I'll dump the tank tomorrow, check the temps best I can with my thermal gun and try to work out when I get a boil. Not as easy as it sounds as the stratification in the tank is very notable. I was draing from the bottom and when the thing was steaming at the top, I could still just hold my hand underneath the water coming out the bottom. Filling from the bottom I can take out 60% of the water and still get near boiling. Probably really needs a circ pump to stir it to get any real accuracy but should be close enough.

Been making a lot of boiling water which I have been using to water the weeds in the garden and along the lawn edges.
Very effective, safe, cheap and chemical free weed Killer and you can replant in the garden 30 Min later and don't even have to pull the weeds out. )

[hca]

Heat wise not a lot, there only one element as its made from a tea urn, the only suitable thing I could find at the time without making something from stainless or copper sheet, I use one phase for the control and another for the element and have considered adding a second element on the 3rd phase for boost in warm up. It takes an hour to come up to temp at 2.6 kw which is full tilt and second element would half that time. But I can switch in the temp PID above the pot below the reflux stack to hold it making vapor but not entering the reflux and sound a siren. So just go and do something for an hour and when you hear the alarm come back and its on hold waiting. Quite safe as no volatile vapor rising.

Next bring it up with a steady 1300 watts but no reflux, it will boil off the methanol and acetone fairly quickly and stop not really enough energy to lift the ethanol. That unhealthy stuff is used for firelighters. Next lower the reflux cooler bring it up to 1400 watts and sniff / wetlip check the product, if its ok up to 1950 watts and do the main run (hearts), it will slowdown while still 93%, the bring it up to 2100 and wait till the % drops a bit and the smell changes, also it get a bit oily. Sometimes tweak the input power and reflux position but mainly increase the reflux cooler flow to keep the water exit temp below 40 degrees because the boiling temp of alcohol holds it down, as it diminishes from the reflux coloum the vapors will heat up with the rising fusel oils and water percentage increasing.

Now its producing the headache material, what the chemists blend to maintain the constant Jack Daniels or Johnny Walker taste, to pull this its retract the reflux cooler probe and increase the cooling flow, power up to 2600 watts. At about 80% water it just stops, This recovered product is saved and put in the next mash. Press a couple of buttons on the remote and the rest in the pot tipped to the drain.

So its all about heat input and reflux control but at 2600 watts it enough for the pot size. But if the pot is 3/4 full its all different in fact 2600 watts struggle to lift the last of the tails with the air gap in the boiler. Off hand you would think if its not full it would need less power input but not so, you actually need more!

Stratification also occurs in the still also, its easy to measure the temps vary deeper in the pot with the alcohol water mix but I only measure the vapor lifting off. This off course happens in a cracker stack in the refinery, I have looked at modifying it to use idea this for a non stop run, dribble out water from the bottom and introduce mash midway up the still. But I cant figure the separation of the heads and tails and its already in a 6 meter high room.

But its all about power in to power out in the reflux and product coolers. There is mathematical calculation for all this but I have not got that far, I do have exit metering on both temp and flow in both reflux and product coolers but after all its hobby.

There a very roughly made video I threw together for a friend in France of it running with some description if you are interested.


So as you say, its ideally a lot of heat to start up then lesser and more controlled amount as the process runs. As you say hot water is probably best, Its certainly easiest, super heated steam is very dangerous and we get into pressurised system at high temps.

Fitting low pressure coils in the pot is easy enough, a matrix of small aircon return copper pipe would be ok, that's also the only copper pipe readily available here. Good speed control on a small single phase hot water pump is not realistic. A VFD on a 1/3 hp 3 phase pump would be good but expensive.

But on the assumption the seal is teflon or high temp plastic a pair of offset ball cock valves back to back would do the flow control driven with a dish positioner jack to split the flow from into the pot or bypass return would do. I love those jacks, 12 to 30v, turn counter, inbuilt travel limiters and reversing, and cheap, I use them everywhere.

Boilers, I don't know, but I have seen whats left of some they dragged from Glasgow to in the mountains of Eastern Victoria near home, must have killed a lot of bullocks and horses in the process. They all had the fire at the front and horizontal flues running to the back through the tank, I guess that idea was for efficiency as they knew it in the 1860s to run steam engines. Providing its boiling water and not super steam, maybe that's a way to go for heat extraction with a fairly light construction? It maximizes the heat transfer with a steady flow, may be heat rising in the tube upper can displace the boundary layer you mention?

To produce 5kw at a consumption rate around a litre an hour has me thinking.


For blowers, plenty of dc options from muffin fans to squirrel cage which are easily controlled with cheap Auduino PWM boards these days. I have a couple here on 24v wheel chair motors that cost bugger all, control with a pot or micro. Just nice for optimising your primary and secondary draft inputs maybe?

And Arduinos, they are great for these kind of jobs, the code and libraries are all there, Dont mess with Uno, Megas are are best, bigger faster and if your counting like flowmeters or sat jacks 6 input ints. I have put together a mongrel modbus program with lots of defined includes, basically define how many of what sensor you have, analog and digital IO and the they all fit in a register array. One day Ill put it on github.