tom LUBBERS – Efficient Gasification

Owner - The Log Boiler
View more information about Tom Lubbers.


Gasification is simply the process of burning smoke.  That process can be elaborate or it can be simplified. We use the simplified method, the elaborate method would be secondary air, downdraft, refractory brick all will give gasification but it’s basically getting the smoke to a high enough temperature for the smoke to ignite.

The triangle of fire consists of three equal parts of oxygen, spark and fuel.  If we can get those components evenly matched we are going to get the greatest amount of heat or BTU’s.  If I start changing that, and I change this fuel level and I put to much fuel and not enough oxygen I’m going to get a lot of smoke, low temperatures and low BTU’s.  The same holds true if I change the oxygen level.  If I put to much oxygen I don’t have enough fuel I’m going to bring in a lot of incoming air and cool my temperature and possibly go out of gasification mode, so it’s really crucial to obtain the most amount of heat, the most amount of BTU’s, the most amount of efficiency from the wood is to keep that triangle of fire as evenly legged as possible. To get the most out of that wood fuel we are using.

The circle of fuel really consists of an infinite level of burning.  We are using our wood fuel in log form and finishing in fine ash.  There’s an infinite level of processes taking place, an infinite level of temperature and an infinite number of requirements for oxygen.  So, if I can take that fuel one hour into the burn process I really need to match that up with the correct amount of oxygen.  When I’m three hours into the burn process I need to change that amount of oxygen and as the wood gets closer to charcoal I need very little oxygen to support that high heat, the high temperature.  I don’t want to get rid of that temperature I want to keep that inside of my firebox.  So, we need to control that environment. When we control that environment we measure exhaust temperature and we match that exhaust temperature with our incoming air. We can hold our exhaust temperature where we want it +/-5 degrees set it at the right temperature we get out internal temperature where we need it and the gasification takes place so we don’t go out of gasification.  But we don’t go higher then gasification either.  If we go too high we get too much exhaust temperature, we’re still gasifying in our main chamber but we are losing our efficiency and pushing all of our heat out of our chimney and that’s the last thing we want to do.  So, we set our external temperature, we hold that external temperature, we hit the minimum gasification temperature we want to hold and we keep it there the whole time. The controls, the computer and the blower do the rest and hold that temperature where it needs to be.  And that’s how we get the greatest efficiency with longest burn times and the greatest heat output from each log we put into the unit.

There’s a couple of different ways to gasify, we use a very simple method.   There are other methods, which include downdraft, secondary air, refractory brick; we just hold a minimal internal temperature to do gasification. Let me explain what that is, gasification is simply the burning of smoke.  If I can get that internal temperature high enough the smoke will ignite between 700 and 900 degrees the smoke will ignite.  Wood and smoke have nearly the same amount of fuel so if we can burn the smoke we really increase out internal temperature but we need to get that internal temperature high enough in order to burn the smoke.  By doing that we created that perfect triangle of fire throughout the whole process.  We’ve utilized that entire wood fuel from log form to the fine ash and we’ve gotten the most out of that wood, we got the great amount of efficiency and of course that gave the best amount of BTU’s, the best BTU’s in our clean burning environment.

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