Wood Gas

Power controller made safe

2009-04-14T09:45:00.001-07:00

The power controller for the 240V AC centrifugal fan has now been packaged in an earthed metal casing.

The speed of any 240V AC motor can now be controlled from standstill all the way up to full speed.

Power controller for centrifugal fan

2009-04-08T07:22:00.000-07:00

I happened upon a very useful AC power controller on eBay. The Kemo M028N power control cost about £22, which is a lot cheaper than the equivalent variac. The device can handle anything up to 4000 watts at 240V or 2000 watts at 110V. However, a heat sink and fan will have to be employed for high power devices.

The photo above shows a quick test using a light bulb. The light is dimmed to its lowest possible level. Now, I need to rewire my centrifugal fan to handle AC again, after converting it to DC a few weeks ago. At last I have a controlable fan. No more excuses to avoid completing my downdraught gasifier.

More fan progress

2009-03-26T14:16:00.000-07:00

With many projects on the go, finding time to work on the wood gas project is not easy. Over the past two weeks a photovoltaic system had to be set up. However, it gave me the chance to run the car air conditioning fan on the deep cycle battery and the result was much more promising than running the fan on a wall wart. The fan is a little over-powered so I will need to add a potentiometer to slow the fan down.

The fan I constructed from an electric leaf blower, and built a plywood case for, is now running on an old converted 386 PC power supply. The power supply has a +12V and -12V output and I am using this to run the fan on 24V. That fan is a little under-powered.

Interestingly, the car fan doesn't work well on the PC supply unit and the converted leaf blower doesn't work well on the deep cycle battery. Maybe someone reading this article knows the answer why.

The next thing to do is to build a transition for the car fan so that it can be connected to my no-weld gasifier. At long last I might be firing up the no-weld gasifier during the next week or two. I shall buy some charcoal and run the gasifier as an updraught gasifier just to check the seals and the power of the fans. Then the gasifier will be re-plumbed as a downdraught gasifier if the fans are up to the task. Charcoal is to be used as the planned gasifier will be a small one and charcoal is better than wood for that purpose. Of course, charcoal will have to be made on-site in future.

Constructing a centrifugal fan #3

2009-02-19T03:55:00.000-08:00

The fan is almost complete. All that is needed now is a way of taming its huge power. Controls for moderating air input and output will have to be constructed.

Update 1 - After discussing my problem with other wood gasers I have changed to a lower power DC supply. With a variable resistor I will be able to find the optimal speed. The next task will be to make a transition for the fan casing so it can be connected to the wood gasifier.

Update 2 - Well, the DC worked but made the fan rotate in the opposite direction. So I converted from AC to DC and from blower to vacuum cleaner. After some thought, I turned the coils round, that reversed the magnetic field and now we have a blower again. Now onto making a transition.

Constructing a centrifugal fan #2

2009-02-16T07:20:00.000-08:00

The centrifugal fan is almost complete. As the fan runs on 240V AC a lot of care is being taken to make sure the fan does not endanger anyone.

The following photo shows the fan and a plywood former for a length of thin steel that will act as outside of the fan casing.

The next photo shows the rear of the fan with the AC motor. As you can see there are plenty of bolts holding everything together.

All that remains is for the front face and sides of the casing to be completed.

Automotive wood gas videos

2009-02-14T13:09:00.000-08:00

Here are a series of five videos on YouTube, demonstrating how an automotive wood gas generator works. The most detailed videos I have seen.

National Geographic - Car running on wood - Part 1

National Geographic - Car running on wood - Part 2

National Geographic - Car running on wood - Part 3

National Geographic - Car running on wood - Part 4

National Geographic - Car running on wood - Part 5

Handbook of Biomass Downdraft Gasifier Engine Systems

2009-02-07T05:57:00.000-08:00

I am adding the Handbook of Biomass Downdraft Gasifier Engine Systems to my list of gasification reading materials.

This document is available for sale on some websites but it's actually in the public domain.

The handbook covers all aspects of gasifier designing, building and use of woodgas as an engine fuel source.

PDF document - Handbook of Biomass Downdraft Gasifier Engine Systems

Stationary engine powered by updraught gasifier

2009-02-04T04:30:00.000-08:00

Here is a simple but very effective gasifier running an engine. The gasifier would appear to use a forced-draught as air input as there is a blower rather than a sucker.

The wood gas is taken from directly above the pyrolysis layer so it would make this an updraught gasifier rather than a downdraught gasifier, which takes gas from below the pyrolysis layer.

Normally, an updraught gasifier is not to be recommended but the use of charcoal rather than wood makes for a cleaner gas. Looking at the flame in the combustion chamber, there is certainly a blue flame there.

Later in the video, we see the wood gas being successfully ignited.

It is good to see such a simple but effective gasifier in operation.

Constructing a centrifugal fan #1

2008-11-21T06:09:00.000-08:00

A centrifugal fan is essential for running a downdraught gasifier. However, searching for a fan can almost be impossible or too expensive if you are lucky enough to find one. After purchasing How to Design and Build Centrifugal Fans enough information is at hand to build a fan from scrap materials.

In the picture below we can see one side of a fan cut out of a piece of plywood. The correct dimensions for the fan required are taken from the book.

In the next picture we can see two plywood framing pieces cut out for both sides of the fan. Below the framing pieces a sheet of light gauge steel has been cut from a vegetable oil can that will act as a shield to protect the plywood.

Centrifugal fans

2008-11-14T04:13:00.000-08:00

Probably the hardest task, when making a gasifier, is the blowing/suction fan. Thanks to the famous Gingery engineering family there is help at hand. How to Design & Build Centrifugal Fans for the Home Shop is packed with everything you need to know about constructing the right fan for the task at hand.

There are five chapters; fundamentals, design, construction, testing & measurement and applications.

After experimenting with various fans, that were woefully underpowered, I am sure this new book acquisition will help me to build the right fan. The applications chapter even has details on building a cyclone separator, ideal for cleaning ash out of your wood gas.

The book can be bought from Amazon - How to Design and Build Centrifugal Fans

Time to dust off my tools

2008-11-02T02:22:00.000-08:00

With all my vegetable crops taken in it's time to start tinkering again. I shall be concentrating on improving my wood gas stove, as a good stove is more of a priority, at the moment, than a gasifier producing engine fuel. I expect to be living rough over the winter whilst I look for some farmland to buy.

Improvements I want to make to my wood gas stove are; a wind shield for sheltering the stove whilst cooking outside, holders for suspending pots at different levels above the flame and a conversion to make the stove an indoor heater.

No-weld gasifier made from clay

2008-10-07T16:22:00.000-07:00

Here is a video showing another method for building a no-weld gasifier. This one uses clay as the basis for various chambers. Plumbing is still performed with steel tubes.

Many people are put off by the thought of having to employ welding to build a gasifier. The idea of building a fully functioning downdraught gasifier without recourse to welding, and still being to produce gas good enough for a generator, will hopefully get more people interested in building their own generator.

Build your own simple MIDGE gasifier (plans on the left-hand side) and see how simple it is to gasify wood. After you have understood the principles of gasification, and see how it applies to downdraught gasification, then it does not matter how you build your gasifier.

Wartime gas-powered van on Jersey Island

2008-07-18T09:02:00.000-07:00

This is a photograph of a gas-powered van on Jersey Island, prior to occupation by German forces.

The gas used was coal gas rather than wood gas and was pumped into the gas bag, on top of the vehicle, prior to travel. The vehicle's range was about 30 miles.

Prior to the discovery of North Sea gas, towns in the United Kingdom were supplied with coal gas, which was produced by the gasification of coal.

click image to enlarge

Operating Engines on Woodgas

2008-06-25T02:15:00.000-07:00

I have found a very useful slide show on wood gasification. There are 100 slides covering all aspects of wood gas theory, history and operation. No stone left unturned, a recommended read.

Slideshare - Operating Engines on Woodgas

Constructing a blower - continued

2008-06-20T15:12:00.001-07:00

The blower has been completed.

First, the end of the drum holding the fans was trimmed and tabbed so that it could accept the other end of the blower enclosure.

A hole was drilled in the drum end so that the wires from the fan could be fed to the outside. The wires are visible just below the bolts holding the fan in place.

The bottom off another 20-litre drum was cut off. This end of the enclosure was measured to provide just enough clearance above the fan.

Two holes were drilled into this part of the enclouse. These holes take tank connectors and act as the gas inlet and outlet.

The two ends of the enclosure were pressed together and the blower tested. The aperture for the gas inlet is a little small. It will enlarged when the rest of the gasifier is built.

Constructing the blower has given rise to some ideas for its integration into the gasifier so they will now be investigated.

Constructing a blower

2008-06-16T13:08:00.000-07:00

This is a work in progress and will be appended to the No-Weld Gasifier instructions in due course.

A blower is important in gasifier manufacturer, either for blowing air in or drawing wood gas out.

In the case of a downdraught gasifier, the blower is used in place of an engine to draw wood gas out of the gasifier until the gas is of sufficient quality for the engine to be started.

As part of the no-weld ethos, a blower has been constructed from scrap. In this case a car air-conditioner fan and vegetable oil drums were used.

In the first photograph we see a typical car fan.

The intention is to build a metal casing around the fan. Gas can then be drawn via an inlet pipe and forced out by the fan through an outlet pipe to a flare. At the flare the gas can be bunt to determine its quality. To facilitate the construction of the blower the two halves of the fan casing were prized apart so that the fan could be bolted into the blower housing.

The "squirrel cage" of the fan can clearly be seen. At the rear is the motor and other end of the rotor shaft. This shaft would rub off the intended metal casing so the assembly had to be held clear.

In the next photo you can just about make out a sandwich of plywood which holds the fan proud of the metal drum. The fan was bolted to the drum through the plywood sandwich.

Exact details for attaching the fan to the drum will not be given as every car fan is different. It will be necessary for the builder to discover the best way for themselves.

The next stage of construction is to fit the other half of the drum and then attach the inlet and outlet pipes. The blower can then be tested to determine its suitability.

MIDGE stove update

2008-06-10T00:10:00.000-07:00

This article details changes we made to the original MIDGE stove. When building a wood gasifier, care must always be taken to prevent air from entering from where it should. If air is permitted to enter from anywhere other than where it should then the gasifier will not operate properly and can even explode under certain circumstances.

When first built, the combustion chamber rested precariously on four bolts attached to the outer chamber.

The weight of the combustion chamber pushed down on the bolts and allowed a sizeable air gap to appear between the top of the combustion chamber and the top lid. This gap allowed cold air to get to the secondary air holes from the top rather than entering through the primary air holes at the bottom.

To remedy this problem the hole on cowling lid was widened by cutting small tabs around the circumference of the hole so that the hole the combustion chamber could just pass through. The tabs were then folded back onto combustion chamber to lock it in place.

The area around the tabs was then sealed with fire cement to ensure there were no air gaps, as can be seen in the following photo.

Not only did this reduce the air gap but also meant that the supporting bolts could be removed from under the combustion chamber as the cowling lid now supported the combustion chamber.

Another test firing was performed. The air throughput was much enhanced resulting in much higher temperatures being read.

In the following photo we see a burn with a stove pipe on top of the stove, which increases the air throughput.

The draught was such that red hot particles of ash were ejected from the combustion chamber. A draught control that changes the size of the primary air intake may be needed. The very bright colour of the combustion shows great heat being generated. Small jets of gas can be seen emanating at the perimeter where the secondary air holes meet the wood gas.

Commercial MIDGE stoves are a waste of money

2008-05-27T07:55:00.000-07:00

Not only are commercial MIDGE stoves a waste of money but they also go against the spirit of wood gasification. Self-reliance is the key to wood gasification, the ability to provide for yourself and for others in times of hardship.

If there was an energy crisis then popping down to the shop for a MIDGE stove is not an option. There won't be any. Nor will there be an Internet for you to purchase one on either.

Another reason for not buying a commercial MIDGE stove is that for some reason they come with an integral battery operated fan to produce a stronger draught. The battery operated fan also goes against the spirit of wood gasification. Where are you going to get batteries from in an emergency?

A well-built gasifier simply doesn't need a forced draught. I have boiled water and cooked meals on my MIDGE stove. That is all they are meant to do and a handmade one does the job perfectly.

Read the plans. Find some cans. Make gas!

MIDGE stove plans - The Complete MIDGE (pdf)

No-weld downdraught gasifier #3

2008-05-27T07:23:00.000-07:00

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.

No-weld gasifier sections:

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

#2 - Building the combustion chamber

#3 - Completing the combustion tube

No-weld downdraught gasifier #2

2008-05-27T06:27:00.000-07:00

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

Ferrocement resources

2008-05-26T09:16:00.000-07:00

In a previous post we mentioned the possibility of using ferrocement as a way of building a no-weld gasifier. At the moment we are using lighter gauges of steel and bolting together our no-weld gasifier. To create airtight seals we are using fire cement.

It is not too far a step to start using ferrocement to seal the gasifier from air and wood leakages. There are also advantages to using ferrocement as a way of protecting the lighter steel gauges from excessive heat, which cause buckling.

For the time being we will continue without ferrocement and consider its use after a test run.

Ferrocement - resources

Electricity generator running on wood gas

2008-05-26T06:17:00.000-07:00

This is a very good presentation about what can be achieved with a simple wood gas powered generator.

Heating water with wood gas

2008-05-23T06:46:00.000-07:00

I was experimenting with Big MIDGE last night. Attempting to find out the minimum amount of wood chips I would need to boil 1 litre of water. Not much was the answer. Approximately 200g is the amount of wood chips required.

It is surprising how efficient these MIDGE stoves are. They produce no smoke, can be used indoors so long as there is adequate ventilation, and produce little ash. They give off an awful lot of heat and most of it is directed precisely where you want it.

Upcoming experiments include constructing a heating coil from copper pipe and attempting to heat a larger mass of water using the thermosiphon effect. I would like to heat enough water for one or two showers, washing the dishes and a cup of coffee per day.

Ultimately I would like a larger gasifier that during the course of a day can heat a large heat store. This store would be a heavily insulated tank holding 10,000 or more litres of water. The intention would be to heat the store to provide enough heat for a week of hot water and underfloor heating.

A wood gasifier is ideal for this as it is very efficient. Most of the heat generated would go into the store. The wood chips would be simply created from waste wood mass. There would be no need to fell large trees, which could then be sold on for income rather than my burning here. Besides, chainsaw work, bucking and splitting does my back no good at all.

Operating a wood gas stove

2008-05-23T06:40:00.000-07:00

I have created a better video of the MIDGE stove in operation. I'm no Orson Welles but I do come in on budget.

The stove is a particular type of gasifier known as an 'inverted downdraught gasifier'. Essentially, that makes it an upside-down downdraught gasifier. The difference being that the wood gas is immediately burnt in the inverted gasifier but in the normal configuration it is tapped off for running an internal combustion engine.

The inverted downdraught gasifier in its most basic form consists of one can suspended inside another. The outer can acts as a cowling permitting air to enter its primary air holes where it can pass into the inner can. The inner can has holes at the bottom, in the form a grating which aids combustion of the fuel, and a ring of secondary air holes at the top which create an air/fuel mixture with the wood gas.

Fuel consists of wood chips. This permits easy fuel collection from broken tree boughs and the sort of waste that owners of log burning fires reject. The chips are packed down into inner combustion can and a small amount of some flammable liquid (spirit or paraffin) is dripped on top so as to get the fuel to sustain a hot flame long enough for char formation.

A fire is lit on top of the fuel, which results in a char layer forming. Beneath this layer is the pyrolysis layer where wood is converted into hot wood gas. Combustion continues down through the wood chips, converting the chips into charcoal which is then reduced to wood gas. The wood gas rises up, meets hot air at the secondary air holes and ignites.

You can think of a MIDGE stove as a device for making charcoal, which is then reduced to various volatile gases and a small amount of ash. The operation is very efficient, is virtually smokeless and yields little ash.

YouTube - Wood Gas Stove

No-weld downdraught gasifier #1

2008-05-21T06:08:00.000-07:00

Much is made of wood gasifiers being useful in emergencies. However, most are made in today's time of relative plenty. Constructors have ample time to source materials and then weld them together with state of the art equipment.

What if we were in an emergency? What if the materials available were not of a high grade? What if welding facilities were either not available or inappropriate given the materials we had? All of these questions made me think of building a no-weld gasifier, using common materials that anyone might have and tools that could easily be found.

In these times of dwindling resources, scrap metal is snapped up by scrap dealers and is hard to find. In an emergency, looking for quality scrap metal might not be an option. Here are some typical scrap tins that you might find in your house or on a rubbish tip.

Tools used were the kind that can either be found around the home or easily procured. No welding was permitted so fixings either had to be bolted together or merely rested on top of each other. Sealing to prevent gas escaping or air getting to where it shouldn't be had to be done with fire cement, which can be found in most hardware stores.

The larger tins are 20-litre vegetable oil drums and are ideal for building the main housings for a gasifier. These drums can easily be cut with tin snips but care must be taken when cutting thin steel as any jagged edges can easily scratch your skin. The metal will not clean and any dirt can enter wounds and cause infection.

This photo shows the top cut off a drum. A serrated edge can clearly be seen.

Serrated edges can be cut into tabs and then tapped down so that no sharp edges are in harm's way.

A firm surface under that part of the drum being tapped prevents the drum being put out of shape.

The result is an open-topped drum that can be used to house the combustion chamber of a gasifier. The fitting at top left of the drum is a tank connector. Any wood gas produced will be sucked out through this port.

Close-up of the tank connector. Connecting it is simply a matter of making a hole in the drum and screwing both parts of the connector either side of the drum wall. No welding required.

In the next section we will build the combustion chamber that sits inside this gas collection drum.

No-weld gasifier sections:

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

#2 - Building the combustion chamber