As I mentioned before when I did my rocket grill project, I wanted to find a way to take wood gas from the rocket stove and channel it to the side burner. Here’s some work I’ve done, though there is a lot more to do to get it working:
We see from the video that it is indeed possible to collect some wood gas from the rocket stove for combustion elsewhere. With some improvements, more gas should be able to be drawn off, certainly enough for a sustained combustion.
This has got me thinking about using a rocket stove to build a wood gasifier. Note the way the gasification grate is made. Here’s a video on how I built it for reference:
What would happen if we put a simple butterfly valve at the top of the heat riser. Start the stove as normal with the valve open. In a minute or two when gasification begins, the intake of a small engine is connected to the air intake of the grate (with the appropriate coolers and filters). As the engine is turned over, the butterfly valve is shut and the uncombusted wood gases are drawn through the air injection holes of the grate. From there, they pass through the coal bed, get cracked further, are cooled and filtered, and finally fed to the engine for combustion.
I see such a system as having a great potential for a small wood gas system. Wood can be added to the fire with no smoke production, start up times should be very fast, and construction is very easy.
It is a rough idea, but one I plan to develop as time allows. Let me know what you guys think in the comment section of the first video in this post. This would make a great open source project.
Spring is in full swing and grilling is one of my favorite outdoor pastimes. I had an old propane grill that needed a new burner assembly, but I decided instead of buying propane, why not grill with sticks from my yard?
If you have followed my blog for any length of time, you might recall my 13 block rocket stove. I decided to use this as the heart of my project. Here’s two videos that show how I got combined the rocket stove with the old propane grill and how I made the system better:
It only takes a couple of minutes to bring the grill up to temperature, so propane holds almost no advantage over wood. Nearly all the trees on my property are oak, so I have no shortage of hardwood to grill with.
A project I am currently working on is taking wood gas from the bottom of the heat riser. My plan is to use it to run the side burner with. I have successfully gotten wood gas from the inside of the stove, but not enough to sustain the burner. I’ll continue working on it. In the future, I plan to upload videos of the wood gas burner as well as some cooking videos that illustrate how well it works.
Forced air induction is a great feature to have on a wood burning device. It is like a supercharger, boosting the amount of oxygen available, increasing heat output. It also gives you greater control over the fire, which is great when you are trying to maintain a comfortable temperature indoors with a wood boiler. Here’s some details on how I added forced air induction to my DIY outdoor wood boiler:
It works by kicking the blower on and off based on the water temperature. Wood boilers are designed to run around 180*F. By setting the fan to kick off at 160*, natural induction allows it to slowly rise to the 180* mark, thus lowering BTU output and burning the wood slower. If you set the blower to kick off at 180*, BTU output is increased to 120,000 BTU per hour, taking the chill off the house rapidly, and consuming 22 pounds of wood an hour.
I have the furnace blower set to kick on at 165*. This compensates for the thermocouple having to read water temperature through the copper pipe, preventing boil overs. It turns off at 160*, allowing the water temperature to rise.
I’ve been experimenting with using an alarm to let me know when to add wood to the fire. So far, it has been a bit problematic. If I can work the bugs out, I’ll be sure to share that system.
I have yet to find a deal on a generator to convert to wood gas. Because of this, I’m going to have to build my own. Right now, my power back up system is made of a 24v computer UPS connected to two deep cycle batteries in series. These are maintained by grid power and give me up to 4 hours run time for my outdoor wood furnace. This is fine for short outages, but a good ice storm will leave me needing something better.
I recently picked up a couple of these alternators to use for my project:
At 840 watts, they produce more than the 650 I need to keep the wood furnace running at full heat output. I have a 3 hp small engine, which should produce adequate power even with wood gas to run this alternator.
The next phase of this project is to source the materials I will need to build a wood gasifier. This project has been a long time coming, but now that I have a welder, construction should go smoothly once I have all the materials needed.
As I mentioned in the build video, I was planning several modifications to make the stove more efficient and user friendly. Here is a video that shows what I have done so far to accomplish just that:
As you can tell, I’m bringing more heat indoors with a lot less being wasted out the flue. There are still many things I plan to do to make the stove even better and I’ll be sure to continue documenting the modifications I make.
The circulation system I designed is very simple, yet it has many safety features built in. It is also the expensive part of the whole setup, with the exchanger being $107, the pump $75, the thermal switch $15, and the piping being around $100. I already had the blower from my old central heating system and the blower box was built from scrap wood. The boiler itself was under $100 to build.
This really isn’t bad when you consider the cost of a modern gasification boiler.
Here’s my video on how I hooked up my outdoor wood boiler to a very simple heat exchanger system:
I recently purchased a infrared thermometer for obtaining data on my stove projects. Tonight, I let the stove come up to operating temperature and run for an hour before taking measurements. The results are interesting.
The ambient air temperature tonight is 61 *F. On the body of the stove, the temperature is between 180 and 197 *F. The stovepipe measured 343 *F. The door was really cooking at 572 *F. Coming in at the coldest was the belly of the stove at 112 *F.
I tried measuring the temperature of the grate, but it was too hot. My thermometer only goes to 716 *F. I’ll have to use a thermocouple for internal temperature readings.
From these observations, we learn a few things. First, that door must be insulated as it is bleeding heat. Second, the water tank is definitely pulling heat from the fire as the stove pipe is colder than the door. Lastly, my homemade insulation does a good job at keeping the heat in the fire.
Wood heat has gotten expensive with upcoming EPA regulations going into effect. The new gasification wood stoves and boilers promise cleaner emissions and better efficiency, but will take a couple of years to pay for themselves. I’m not claiming to have built a boiler that outperforms them, but it is smokeless and will pay for itself in a month.
Here’s the full video on building the boiler itself:
In my next video, I’ll show how I bring the heat indoors and safeguard the system against power outages.
I plan to release the first video by the end of this week. This video will show the construction of the boiler itself. The next video will detail how to hook it up to a pump and exchanger to bring the heat inside. The final video will show modifications I make to the stove to make it even more efficient.
In the mean time, I hope you enjoyed the preview video!
While carburetors have disappeared on automobiles, they are still found on small engines. They are notorious for being the cause of many small engine problems. To counter this, I decided to build an experimental vapor carburetor from a couple of gate valves, pipe fittings, and a old propane tank. Here’s what I came up with:
We can see from this video that the basic principles work remarkably well, though this design isn’t very portable. A couple of things are needed to make this better. First, an air filter is needed. Some sort of anti backfire device would be good as well. A piece of stainless steel scrub pad inside the air intake T-fitting would do the trick. Last, but not least, a more portable design.
Vapor carburetors are often made out to be a magical device that can turn a car into a 100+ mpg beast. Its simply not going to happen. A car that requires 20 hp to propel it 60 mph with 100% efficiency could get 134.4 mpg. We know the overall efficiency of a car is nowhere near that. How about a more realistic number like 30%? The car would get a tad over 40 mpg, a number that is still very difficult to obtain.
Many vapor carburetor designs are supposed “crack” gasoline into lighter more volatile fuels, this being the mechanism behind the 100+mpg claims. The problem with that idea is that these lighter fuels have lower amounts of energy, requiring more fuel consumption to get the same power output. There is no free lunch out there.
That doesn’t mean we can’t develop cars with better fuel mileage. With the incredible efficiency of modern fuel injection systems, we just aren’t going to get better mileage by changing the fuel delivery system. Finding ways to utilize waste heat and recovering energy lost in braking stand to give better mileage results than a magical vapor carburetor.
At any rate, the vapor carburetor is easy to build and can be tuned to work with many small engines. The vapor carburetor lacks the more complicated mechanisms and tiny fuel passages of modern small engine carburetors, which should lead to better reliability. There is great potential for computer controlling one of these, which would lead to better small engine life.