Wood Gas: No-weld downdraught gasifier #3

In this section we complete the combustion tube inside the combustion chamber. Then we marry the combustion chamber to its shroud.

You will remember that we had introduced the combustion tube into the hole at the bottom of combustion chamber. Tabs were cut to hold the tube in place.

After checking that the tube has an idea fit we remove it. Four holes are drilled into the side walls of the combustion tube. These holes will take a bolt each so that they take the weight of the tube.

Next, a restraining band is made from a thin strip of steel (such as was leftover when cutting the 20-litre drum. Four holes are drilled into this band so that it can be held in place by the four bolts on the side wall of the combustion tube.

Holes are drilled into the bottom, closed end, of the combustion tube. This allows ash to fall out of the tube.

A disk of metal sheet is cut and entered into the combustion tube. It rests upon the bolt heads and acts as a throat inside the combustion tube. A hole (or holes) will be cut into this to allow char to fall into the combustion tube.

The combustion tube is placed back into the combustion chamber such that the tabs holding the tube in place are caught between the tube and the restraining band. This band holds the combustion tube firmly in place.

The combustion chamber was turned upside-down and the gap between the combustion tube and chamber sealed to prevent air from bypassing the char.

Here we can see the combustion tube sitting on top of the shroud we made in section #1. On top of the combustion chamber sits a hopper. Details of the hopper will be given in section #4.