It may be asked why producer gas has not come into general use and displaced imported fuels in times of peace. The reasons are many, but four predominate: (1) Higher first cost, (2) cumbersome equipment, (3) loss of power as compared to petrol, and (4) lack of flexibility.

That producer gas running costs are lower than petrol costs is undeniable. But the easy starting of the petrol engine, its flexibility of control, the smaller amount of space required for the carriage of fuel, as well as the network of pumps whereby petrol supplies are ensured at all times and all places (in other words the selling tech­nique of the oil companies), has kept imported motor fuels in the foreground, and producer gas has remained in the background—a scientific curiosity only.

In the year 186o Lenoir invented the first successful gas engine, which operated on coal gas. This gas was expen­sive and required large equipment for its manufacture. The natural outcome of this was the introduction of a system whereby large quantities of gas could be made quickly, with comparatively small equipment and from low-priced fuels such as coke, charcoal, wood etc. The gas producer satisfied all of these points and so was slowly introduced.

The modern gas producer is made up of three distinct elements, the efficient functioning of each being the deciding factor in the results achieved by the plant as a whole. These elements are:

1. The generator in which the fuel is burnt to produce the gas ultimately used in the engine. This is usually a cylindrical or rectangular metal container holding the fuel and into which air is admitted by means of either a grate or tuyere.

2. A scrubbing or cleaning element which removes from the gas any of the impurities it may contain. The means, of achieving this result are either dry or liquid cleaners, or in some cases a filter through which the gas is drawn.

3.  A cooler or radiator. As the gas is generated from the fuel by means of a fire, the temperature of which is, very high, it will have a correspondingly high temperature which results in a loss of engine power if it is not first cooled down to a temperature of about 130° F. This is done in the cooler, or radiator as it is often called, by passing the gas through a number of pipes which are air cooled.

In addition to the units just mentioned there must be some apparatus in which the producer gas and air mix to form a combustible mixture.

That a gas producer is an inconvenient, bulky, and in many cases, unsightly, piece of apparatus must be admitted. But some of this prejudice must vanish when we consider the important task that it is performing. Nature itself took millions of years to produce petroleum, so it is indeed a technological feat that man, with the aid of a very simple apparatus and some wood, can produce an efficient substitute. Giant hydrogenation plants capable of producing a satisfactory substitute fuel from coal have been built at enormous cost; but the producer gas plant is the only plant that can produce a satisfactory substitute for petrol and be built within the means of any individual.

This book will easily add to your general knowledge of this subject, and will help you as part of the motoring public give more thought to producer gas. Engineers, mechanics, students, experimenters and tinkerers will find the book thought provoking.

UP-DRAUGHT GENERATOR

The simplest form of generator is shown in Fig. 1 and consists essentially of a cylindrical or rectangular con­tainer to which has been fitted a removable air-tight lid to permit the introduction of fuel which is burned on a grate near the bottom of the generator. A door for the removal of ash and one or more holes for the entry of air are provided below the grate. The gas outlet is placed near the top of the container and connects through the scrubbers to the engine manifold.

An English firm, Messrs Solex, has produced a very interesting instrument, illustrated in Fig. 19, for use when an engine is running either on petrol or on producer gas, the two separate types of fuel being available at any time.* The carburettor, as Fig. 19 shows, is made up with an extension to its body so arranged that the carburettor can be cut off entirely from this extension by an interrupter throttle. On this happening, the main throttle from the producer is opened, and thereafter the supply of mixture to the engine is controlled by a third throttle in the ordinary manner.

1. Triple disk valve controlling flow of gas and air.
 

2. Knurled adjusting screw for varying spring pressure on the disk valve.
 

3. Idling gas adjustment screw.
 

4. Gas passage to rear of diaphragm.
 

5. Diaphragm operating the air valve to equalize pressure of air and gas.
 

6. Adjustment for outer spring of diaphragm.
 

7. Combined diaphragm inner spring adjustment and air choke.
 

8. Flange for bolting to the engine

THE PANHARD GENERATOR

FIG. 27 shows the Panhard generator, which is of the down-draught type.
 

It consists essentially of a hopper (A) to which has been fitted an air-tight lid to allow of admitting the fuel. This hopper in turn is formed by an elongation of the cylindrical body (E) which is closed at the lower end by an ash hopper (M). A refractory lining (H) is provided, a steel cylinder (F) being placed outside this. The lining rests on a plate which is riveted to the cylinder. A bell-shaped grate (I) mounted on a pivot can be oscillated by means of a lever (J), thus causing the ashes to fall down into the hopper, from which they .can be removed by means of a handhole (N). A second handhole (L) gives access to the combustion chamber. The lower portion of the hopper is made in the form of a truncated cone so as to deflect the charcoal into the centre of the combustion zone. which, as previously stated, has a refractory lining. A veilleuse, or vent, is fitted to enable sufficient draught to be created to keep the fire alight when the vehicle is stopped. This vent is closed during travelling. A fan (0) is provided to light the generator.

THE BRUSH-KOELA PLANT

The Brush-Koela gas producer is a plant which consists of a generator and two scrubbers; connected as shown in Fig. 32. The generator is of novel design, in as much as it incorporates both the cross-draught and up-draught principles, the former being used for start­ing and the latter system brought into operation for regular use. The change from one system to the other is made by a change over valve. Steam is admitted to the fire by being first vaporized by the hot exit gases. The fire grate is of the hanging basket type, and the starting tuyere is com­posed of carborundum in order to avoid the necessity of providing a water-cooling system which would only receive. occasional use.

This producer is entirely self-regulating, and has an exceptionally long operating range. An automatic air and gas mixing valve (described elsewhere) keeps the mixture in correct proportions under all conditions, and a special idling screw is fitted. These features make the producer particularly easy to handle in traffic.