No-weld downdraught gasifier #2

In this section we detail the construction of the combustion chamber. This is where air from the outside meets hot char to form wood gas.

The combustion chamber is made from two ends of a 20-litre vegetable oil drum. A whole drum is too big so we just cut off what is needed from either end and then join the two ends together.

In the following photo we can see an old drum being cut with tin snips. Drill a hole (using a low setting on your drill) in the side of the drum so that the tin snips can be inserted into the drum wall. I won't give dimensions here. It is up to you to decide what sizes you need depending on what tins and drums you have available. Read the whole of this article before starting work.

Here we can see the two ends of the drum. Keep the strip of metal between the two ends as that will come in useful later.

The bottom end of the drum has tabs cut into its wall section. This allows the top end of the drum to be pushed over the tabs and locked in place.

Now, a hole is cut into the bottom of the drum. The hole has a diameter about 2 centimetres smaller than your chosen combustion tube.

Here we see the completed hole. The hole doesn't have to be accurate, just smaller than the combustion tube. You then cut tabs so that they can be bent up and cling to the combustion tube. This will help hold the tube in place.

Here we see the tabs bent up and clasping the inserted combustion tube. The tube is a tin of about 15 cm diameter with one end open and the other closed.

In the next section we will complete the combustion tube and show the combustion chamber and shroud joined together.

No-weld gasifier sections:

#1 - Introduction - materials and tools, building the combustion chamber shroud

#2 - Building the combustion chamber