Down Draft Biomass Gasifier 

Have you joined the drive on wood forum yet? We have a great group of guys in there to help with any information you could ever need on gassification

@@BigBeavrSlayer I am subscribed to a few of the drive on wood guys. I haven't joined the group mainly because of the difference between our gasifiers. They are able to run on way bigger chunks than I can. I built my gasifier as more of a clone to Flash001usa's gasifier. We have our air intake running right down the center of the hopper with a single "nozzle " right in the center as opposed to jets around the outside. I do enjoy their content and comment on things. They usually do reply to any questions I may have. I think I like Don manes Tracker the best. Always loved Trackers. I think his is charcoal only though. Probably for space reasons. Joe

@@mazdalorean dons was a wood machine in the beginning. There are lots of guys building charcoal system since they are so simple and most of them are running center single jets or single or double flutes. We would welcome you aboard the forum there are guys all over the world on the forum and we always like to help each other out no matter the design, fuel size, charcoal, wood, pellet or chips 👍

@@BigBeavrSlayer how do you join? Where do I go? Joe

Thank you for the reply. The system has been up and running for a while now, but I've been running into some issues. Specifically, the amount of tar gas is more than expected. It could be that I'm piping gas to the generator before the reduction zone is up to high enough temperature. Also the combustion zone is running very hot, especially at start up. I've had to place a shield around my inconel T/C to keep from melting. The temps stabilize once the reduction zone gets hot. Tar is causing the the intake valve to gum up and stick open. Biomass movement is good, with no clogging/bridging. Also, the generator is not producing anywhere near the rated amount of power (6800 watts). it's more like in the 2KW range. I reduced the volume of the reduction zone from what is shown in the video to increase gas movement through the system. It's clear that tar is not being consumed/cracked as hoped. Suggestions welcome. Anyway, I'm eager to resume work and publish more videos. BTW: VB.net software and Phidgets.com I/O hardware are working great.

Yes, feed stock is wood chips sifted across 1/4" screen to remove dust size biomass. Larger strips of bark and such are removed by hand. Bridging doesn't seem to be an issue. Wood pellets could work, but at a cost.

Thanks for the comment. This has been my understanding: the tar gas should be burned (not necessarily cracked) in the combustion zone. The byproducts (h2o, co2, co) is cracked/recombined in the charcoal-rich and hot reduction zone to produce h2, co and other light hydrocarbons. This is where the h2o and charcoal comes from as mentioned in your comment. I've not heard of water drip, but interesting. I think you're right about the too much shaking of the ash grate

@@biomassgasification3883 , so the way we start all these chemical reactions is by heating up the biomass in an oxygen restricted environment, causing the molecules to fragment off of the wood. There is a huge variety of long hydrocarbons that result in this process. The tricky part of gasification is heating these long hydrocarbons up in an environment that is hot enough to break down the bonds (or crack) the various combinations of molecules ( collectively called tars) . So the types of tars that are created completely depends on the environment in which they are made. You can pass the gas through an area that has too much heat and if it travels too fast through combustion, it makes more complex combinations that can become more difficult to break apart. The ideal situation is that the gas can spend more time in the high temperature environments, and through all of your specially designed heat transfer areas, be completely dried and pyrolysized before it gets to the combustion zone. It's also worth mentioning that when you start, and warm up your gasifier, it should be done entirely with charcoal. If you start with charcoal, you eliminate the possibility of tar being created until the system is warmed up. I have already had runs that looked really clean in the color of the flares, and after shutting down, I find tar captured in the filters. I contributed that to using raw pellets during the start up procedure. Lots of smoke equals lots of tar. You should see some moisture in your gas ( not lit ) , but if it's really smokey and the smoke dissappears after you light the flare, your still making tar . The all power labs gasifier has its zones set up a lot like yours. If you run it correctly, you won't end up gunking up the inside walls of the heat exchange surfaces. If you run it wrong, you end up coating these surfaces thereby insulating them, making all your heat transfer designs less effective. This is why I stuck with just using the engine exhaust temperatures to get as much heat into the air and fuel going in the gasifier and stuck with the more traditional approach of a larger cooling system for the outgoing gas. Yeah I waste some of the usable heat, but I never pass tar gas into an area that I can't physically clean. It's a trade off. All power labs have done all the research and if you run their gasifier within the suggested guidelines that they recommend, you won't end up making enough tar to cause any harm. But even with one of these gasifiers, if you don't keep the load on the gasifier consistent enough, your temps can drop to where you make tar. This is where the automation shines. It let's you know you are not within the acceptable range of pressures and temperatures and you can either increase the load to increase temperatures or decrease load , causing temperatures to go down. A famous quote from Jim Mason was you can't solve the tar problem, you can only try to manage it. Something to that effect. Hope this helps without getting you down. It can be very frustrating running these things. Even when I think I understand everything that's happening, I make mistakes. One important lesson to learn is in the use of check valves. If for any reason your blower shuts off while flaring off the gas, you have to remember the system operates in a vacuum and air will rush into the system as soon as the blower stops. This can create an explosive situation by mixing oxygen in with the outgoing gas. Point is, use check valves to prevent this from happening. Hope I'm helping. Joe

@@mazdalorean I appreciate the advice. Regarding the check valves, have you found off-the-shelf items, or did you fabricate them? I've not found anything that has a zero resistance in the forward (towards flare/engine) direction. All kinds of them for fluids, but not for high volume/low pressure gasses.

Thanks Victory. Interesting idea that I had not considered. In none of the papers that I have on down draft designs do they talk about turbulence or circular flow. They talk about calculating number and diameter of the nozzles vs diameter of the throat. My welds are much improved, except for SS. I'm thinking of using refractory cement to cast the combustion/reduction zones. Essentially what is shown in the video made out of SS.

@@biomassgasification3883 I would like to add to your design using refractory cement reinforced with stainless steel short round headless nails. The use of this material can be used at such higher temperatures that stainless steel could not withstand the continuous heat cycles. This is what two different engineers told me over the last two years. They both have experience over the years. You can use stainless steel but the life expectancy is not that great. Using real exotic alloys like inconel is just way to expensive. This is what both have stated from experience. Hope that helps fella.

Chris, for some reason RU-vid never notified me that you commented on this video. Just happened to look and found the comments. I have made so much progress since my last video. I will be posting something sooner or later. Just to give you a preview, I installed a stainless steel generator enclosure at the back of my garage that houses a 13,000 watt generator including wiring to connect to the house as well as an o2 sensor to eventually run the generator on wood. Also fabricated an elaborate exhaust to use the waste heat for use in the gasifier. I wired up a power distribution panel that allows me to adjust the load on my generator in 700 watt increments with the goal of dialing in the temperatures in the combustion zone to consistently crack the tars. I have been getting a lot done in the way of programming. Finally got the touchscreen panelview talking between the laptop, panelview and the plc. Working on laying out my screens now with the goal of not needing the laptop when running the gasifier to interact with the gasifier. Also made a condensate tank that will alert me when it's full. I just don't get too much time these days. Stay tuned because sooner or later I will post stuff. Thanks for watching and commenting. Joe

@@chriskwakernaat2328 I'm sorry Chris, I replied in the comments to the wrong video. My gasifier isn't the square one. Joe