i am going to use 2 thermal fuses. different temperatures on different parts of the system,one on the top of the drum at 110c and one near the base of the burn tube at 220c. one on each lead going to the pump and timer circuit. i thought about those thermal cut outs but not sure if they reset automatically when the temperature drops or if they have to be reset manually. agree for safety i would not trust electronic control if the stove is left unattended for any amount of time. i do like the idea though. it would be good to add some sort of flame failure as well. visions of coming in and finding 25ltrs of manky old engine oil all over the floor.
when i had it set up with the drip feed i used a one ltr can. just lass than the pot would hold so if it did flame out at least the pot would contain the oil.
as regards my flue, i have 2 metres horizontal going to 2 metres vertical outside the yurt. i use a boiler fan on top of the stack to heat the flue initially. this seems to work ok. the idea is when the thermal mass is dried out there should be enough residual heat to create enough draw. will take some pics when i remember.
You can get either or, manual reset, auto reset or even one shot that will only trip once. They are cheap and readily available, you can salvage them from domestic hot water heaters too, over here the ones from hot water heaters are manually resettable too.
Simple schematic for a pump and heater control with a high limit
Sensor for the biodiesel/glycerin layer
I forgot to mention there is a few different OS's supported on the pi, the most popular being linux but you can also run Android, FireFox, Risc etc. See here for an article on various pi OS's: http://www.makeuseof.com/tag/7...n-with-raspberry-pi/
If you decide to dive into the pi I would recommend starting with Qt for your coding, that way you can code right on the pi without having to worry about compiling etc, see here http://qt-project.org/wiki/Qt-RaspberryPi
.The other advantage is your Qt code is cross platform and will work not just on the pi but also your smart phone, desktop computer (any OS), tablet etc.
Simple schematic for a pump and heater control with a high limit
Sensor for the biodiesel/glycerin layer
Yubba yubba, If you look at RS Components online catalog you will see the full range of stats resettable and not.
If you want to be extra safe you can use 2 in series. That way both stats have to be closed for the pump to work but only one has to open to cut off the oil supply. The chances of two of these malfunctioning simultaneously are a zillion to one.
thanks will have a look. i am trying to design a sort of chicken waterer container system. i cant use the standard design as used in turk burners as i need to feed the oil in from above. what i have come up with is a never overflowing pot using a container with 2 tubes coming in from the bottom. 1 8mm for the feed to the burner and 1 10mm back to the oil supply. the whole thing needs to be above the oil supply tank to work. the oil is fed into the container from above using the pump. the 10mm tube is set just above the height of the 8mm tube so that if the pump relay fails on, the oil will still flow to the burner but at a fixed rate,any overflow will pour down the 10mm tube and back into the oil container. seems simple and foolproof as long as the overflow tube doesnt get blocked,hence the larger tube. could even go the 15mm. been scouring the web trying to find something similar but haven't found anything yet. would take a bit of fiddle time to get the flow right of course,but thats the fun bit. filed out tank connector so you can move the larger tube to the right position,then lock it in place.
talk about a picture saying a thousand words........
I think I understand what you mean but yes a diagram would make it easier. It is the one weakness of the pump system, the pump doesnt know if the oil is being burned or not and will continue to pump oil in regardless.
I used to heat my workshop with an alaska vaporizing pot burner. One day I lit it using very cold slightly wet wmo. The cold oil cooled the vaporizing pot to the extent that the flame could not get going properly but did not go out either. After a couple of hours I realized that something was wrong and turned it off. The problem was that the pump had filled the pot to almost overflowing and when I stopped pumping in cold oil it began to vaporize and burn at a dangerously high rate. The body of the stove and the first 2 m of the flue became bright red hot and I had to cool them with a water mister for about an hour before it settled down. I was a lot more careful after that.
yes i know one well. if my case i was using the needle valve system and used to open the needle valve fully to warm the coach up. one day i forget to turn it back down. left it for 10 minutes only to find the whole pot bright red plus the flue. took a while for it to cool down while i was misting the walls with a garden sprayer. just as spike found out. i was using kero at the time. wmo and biodiesel are a bit better behaved, but as he makes clear these things can be very danerous if not treated with respect. still working on a passive self limiting back up design. will post some drawing of progress.
I have had a similar thing happen when I overprimed one of the thermobiles. I probably poured 2 litres of mixed WMO/kerro mixture into the dish (instead of the 1/3 pint)
The red hot colour slowly crept up the sides of the combustion chamber until it was all glowing.
It's an awfull feeling of panic just watching the thing, knowing there is little you can do about it.
after lots of searching i have found the word i was looking to describe what i was struggling with. looks promising as a no pump way to feed a ozerts/spike burner. as i thought there is lots of info when you know what to ask. the keyword is "siphon" what i am planning is called a bell siphon. cant see why it should't work. looks pretty foolproof. it does dump all the fuel into the stove at once, but that is not a problem once you get the amount right. if it goes wrong it just stops. a overflow to another container will catch the oil if it does stop. i was thinking of using a valve to set the inlet flow speed. its the same idea as those urinals that flush automatically. you could use a pump to return any overflow to the top tank.
Thats an clever mechanism and Im sure will be useful.
I had an interesting couple of hours today myself. I opened a 200 litre drum of WMO and suspected the oil was very wet so I filled a cup and switched over the supply hose on the pump to try out this oil. Sure enough as soon as the new oil reached the burner it began to crackle like a frying pan frying sausages but the temperature of the stove went up from 330 to 375°C. It wasnt a temporary increase, it stayed at that temp until I reconnected the dry oil. The burner also roared quite a bit louder. Ive read about oil/water emulsions before but was never convinced by the explanation of them
What seems to be happening is the water instantly turns into steam upon entering the primary pot and that means a much increased volume of gases are moving up through the secondary tube. This increases the venturi effect that draws in more air at the secondary air intakes, creating the lean burn that Ttommy mentioned a few pages back. This would explain the higher temp and the louder noise..
I tried to calculate how much water was in the oil but my carbide manometer ran out of tube at 5000ppm. Ill try a rescaled test tomorrow.
many many years ago (olden days) when I used a drip oil heater to heat my shop I also dripped water into the pot this greatly increased the heat out put and reduced the amount of wmo I needed. I thought it had something to do with the steam and also the increased oxygen in the burn pot.
" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
just tried the thermal cut out idea. i used a thermal fuse, doesn't work. i placed it on the flue after finding a suitable spot with the ir laser thermometer. stuck it down and turned the pump on to continuous. after a couple of minutes the flame hadn't changed much and the flue was the same temperature. i now had a half full pot of oil, if i hadn't turned off the pump i am sure the pot would have overflowed. not wanting to leave it i have been sitting in a nice warm yurt for 2 1/2 hours while the oil burned off. the influx of cold oil cools the pot down so no fast temperature rise.
of course the easiest option is to turn the thing off when you go out. it seems to happily burn for around an hour after i turn off the pump anyway. still trying to crack how to make it failsafe. i thing something mechanical using gravity is going to be the way forward.
My uncle tells me about an oil burning stove his family had when he was a kid. The family Business was a Bus company so used oil was in very plentiful supply.
He describes how the oil flow was so many drips per minute and the water was so many less. The water made the oil burn faster and hotter.
I researched this and the reason the water in oil makes it burn hotter is because the crackle is the water steaming as we have all worked out. It's a somewhat violent reaction to scale and what happens is the water basicaly atomises the oil when it spits it around giving it more surface area and therefore allowing a faster burn.
There is a tradeoff however in a couple of ways.
One is it takes energy and a good amount to get water to change phase from a liquid to a gas. With My WVO for the vehicle I always dry it because the car performs much better. It dosen't lose power with energy being used to change water to a gas.
The 2nd spinoff in a stove is that the water can create steam keeping the burner and flue cleaner.
I run water injection in my engine for this very reason and fully believe in it's cleaning abilities.
In updraft burners there was something I played with for helping the burn rate.
I didnt drill holes for the secondary combustion. I cut Triangles or "A's" with an angle grinder, just the uprights and left the bottom attached. I pushed the metal in so as to actualy cause a restriction to the airflow. If you look at wind tunnel vids and understand a bit about aerodynamics you see that behind a restriction is a low pressure system and that creates a negative pressure area or a vaccumm. In this case as the flame rises up the chiminey, Hit creates a hit pressure area as it passes the tabs pressing inwards and as it goes past there is a low pressure area which pulls the air in very well and also creates turbulance which mixes it.
You can see the effect working in the flame swirl. I tried The point of the "A" up and I tried it down and both appeared to work equally well.
That in my testes worked much better than holes. The main reason was I couldn't ever seem to put too many slots in the Combustor area and for a given length of section ( I use fire extinguisher bottles with the ends cut off) I could get a much cleaner burn as evidenced by less smoke and far greater heat. This was evidenced by how far up the thickwall pipe flue I could get to run red hot.
The other main thing to increasing power was to give the oil a preheat of sorts buy running it down the inside of the combustor rather than straight in the pot. The trick here is you have to keep the feed line cool or the oil will coke and carbonise blocking the pipe off. I made a tab at the top of the Combustor area and pused it out rather than in like all the rest and dribbled the oil down the side like that. I was careful to leave an uncut section from top to bottom so the oil didn't escape. It seems to work very well because it keeps the oil in the pan hotter.
Initially when I tried the idea I did have an amount of oil coming out one of the slots I cut but interestingly it was vaporising and the smoke was bing pulled in very quick. By co incidence the pan top where the combustor is attached in concave being an old pot lid and the oil gathered there and pretty much vaporised around it and was pulled in without any odour. It did however cause buildup after a while to with the theroy proven and wanting to try some other things I cut a new Combustor with all the open area I could get in the thing and that worked great.
I'm surprised in that the open area is obviously many times that of the diameter of the flue itself but the pull of the draft down to the pot seems plenty.
That said, wether with holes or slots in any amount, I have never been able to get perfectly clean combustion out of these things. I'd thing that was because of not enough air or mixing but I can throttle the thing right down on both primary air and fuel and it will have some visable smoke the whole time. Sometimes you have to look for it and when the thing is cranked it's unmissable but it is not the pure, clean, warm air smell only I can get with my forced air burners at infinately higher outputs down.
As far as all the controls go, I would just keep it simple with a pumped fuel feed.
I have NEVER had one of these burners go out yet and once up to heat, I can't imagine why it would.
Do other people have a problem with keeping them lit?
I would just use a timed pump to set the fuel flow. As long as it dosen't go out, I can't see any other problem. And, I can't see why they would go out.
Perhaps another way of doing this fuel thing could be a bit out of the box like a seperate bowl for a float. It could be like a carburettor on a car, as the fuel level drops the needle opens and admits more fuel and when it's at its level it shuts off. You could also use a float switch for a pump. These are readily available off fleabay. The other thing would just be for a high limit. If the level got to high it shuts off the pump or a solenoid on the fuel line. There are NO and NC float switches available.
It would not matter how remote the float chamber was from the burner, only the level would matter and it should be easy to keep the oil high enough so the inlet remained cool so the supply line which would be best as a larger diameter was more resistant to coking. Muself, I'd be looking at feeding the oil from the bottom of the pan as that's where the oil will be coolest.
Primary air feed is also far more regulating than the fuel level in the pot. I run mine in batch mode where I fill the burner pot with 4L of Oil and control the heat with the primary air. I can make that 4L of oil last 20 Min or 3 hours depending on the primary air. I never change the secondary air, it always runs with all the slots in the burn chamber wide open.
There are flame sensors available as used on conventional burners and I saw one for the Arduino the other day.
i have thought about the cooled tube in the side of the pot idea. i am a bit reluctant to try that with the present pot as it is cast iron and i am not sure i could get a good seal. it is also curved which doesn't help. if the outlet tube was on the bottom i could use the chicken feeder system. getting a brass fitting to stay sealed to a cast iron pot would be tricky. not sure if you can braze cast iron. that would be one way around it. finding a steel pot would be another.
did some figures for the bell siphon. if i can get it to work, dumping 150 cc of oil in the burner at a time should be ok. that will put 20mm of oil in the bottom which should be fine. just need to see if such a small siphon will work ok.
after puzzling over how to make fairly failsafe method to run the spike burner from a peristaltic pump i think i have come up with a good way to do it. to recap i am using a 555 timer circuit to drive the pump. if the circuit should fail and the pump stays on this would lead to the oil level getting to dangerous levels. what i propose is to have another identical timer circuit set to switch for slightly longer. the output from timer circuit A is used to drive timer circuit B which drives the pump. if either circuit fails on the oil volume will only increase slightly. i know 555 timers drift a little but this should not make a great deal of difference. the chances of both circuits failing on is possible but highly unlikely.
Hi guys, long time no see.
Just an up date on the Burner control software I developed a few pages back. I have been running a burner on this in my workshop all winter and have refined it to the point where I am happy.
I added 3 LEDs to the circuit on pins 2, 4 and 6
I changed the adjustment to alter the pulse rather than the interval.
I use it to control an Aspen peristaltic pump that delivers 6 litres per hour if run continuously.
I added a fail safe, if the temp of the flue goes beyond a preset level the oil supply is turned off for 60 secs and then the Arduino checks to see if the temp has fallen sufficiently before switching the pulse on again.
This setup can now compensate for wide variation in oil quality.
I have printed the program below so anyone who wants to use or adapt this program is very welcome.
// Project .. A self regulating oil supply to a burner.
#define pump 8
float voltage = 0;
int celsius = 0;
float sensor = 0;
int hotTemp = 60; //adjustable temp above which pulse decreases
int coldTemp = 40; //adjustable temp below which pulse increases.
int tooHot = 80; //switch off for 1 minute.
int pulse = 2600; // time the pump is on in milliseconds
int interval = 4000; // time between pulses in milliseconds
int adjust = 300; // time that the sketch will increase or decrease pulse.
pinMode (2, OUTPUT); //sets pin 2 as output and lights blue LED.
pinMode (4, OUTPUT); //sets pin 4 as output and lights green LED.
pinMode (6, OUTPUT); //sets pin 6 as output and lights red LED.
pinMode (pump, OUTPUT); //sets pin 8 as output and switches on pump
void loop ()
//read the temp sensor and convert to degrees C
sensor = analogRead(0);
voltage = (sensor*5000) / 1024; //convert raw value to millivolts
voltage = voltage - 500; //remove voltage offset
celsius = voltage/10; //convert millivolts to celsius
if (celsius <= coldTemp)
digitalWrite (2, HIGH); //lights the blue LED.
delay (pulse + adjust); //increases fuel flow to aid fast startup.
digitalWrite (2, LOW);
delay (interval );
else if (celsius > coldTemp && celsius <=hotTemp)
digitalWrite (pump, HIGH);
digitalWrite (4, HIGH); //lights the green LED.
digitalWrite (4, LOW);
else if (celsius > hotTemp && celsius <= tooHot)
digitalWrite (6, HIGH); //lights the red LED.
delay(pulse - adjust); // cuts back fuel flow to reduce temp.
digitalWrite (6, LOW);
delay (interval );
digitalWrite(6, HIGH); //lights red led
digitalWrite (6, LOW);
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