SUPERCHARGING WITH PRODUCER-GAS.
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A New French Installation Which Permits Producer-gas to be Used in a Petrol Engine Without the Need for Altering the Compression.
ANEW charcoal gas-producer made its first appearance at the French Motor-Culture Week last October, where it carried off the first prize. This producer, which is known as the Malbay, has a supercharger incorporated in the system. From the immediate success obtained it would appear that the use of forced induction gives a very real advantage with producer-gas, whatever its value may be when petrol is the fuel employed.
One point in favour of the Malbay system is the fact that no alteration to the compression of an engine need be made when it is fitted. With the ordinary type of gas-producer for motor vehicles it is necessary to raise the engine compression in order to obtain satisfactory results, and this is usually done by machining the bottom face of the cylinder block. If the compression be not raised there is a very serious falling off in engine power.
The Malbay generator is on more or less standard lines. The fuel hopper is placed immediately over the furnace, and the latter is surrounded by a small annular boiler, as steam injection is used.
The air which enters the generator is first warmed by a muff on the engine exhaust pipe ; it is then saturated with steam and conducted downwards through spiral tubing to the base of the generator,
B24 where it escapes upwards into the furnace. The firebox is provided• with a rotating grid at the bottom ; this can be turned from the exterior for the purpose of cleaning the firebars and preventing caking of the burned fuel. Two successive cleaning processes are employed. The gas first passes into a cooler and washer containing water. Here it is thoroughly cooled and the larger particles of dirt are deposited in the water. The washer or cooler con
talus two compartments connected up by a number of small tubes. The chief feature of this portion of the appliance is the fact that the walls are air cooled, and the gas tubes are contained in an air jacketing. Cold air is driven through this jacketing by means of an ejector arrangement worked off the engine exhaust. From the first purifier and cooler the gas reaches a second chamber also containing water. The pipe conducting the gas into this chamber ends in a wide funnel, through which the gas is projected downwards on to the surface of the water. The upper part of the chamber is fitted with two trays of coke, and the gas is dried in passing upwards through these.
The Malbay compressor is rather similar in form to the " exhausters " commonly used in gasworks. It is a comparatively slow-speed blower, usually geared up at about 2 to 1 from the engine crankshaft, or even run at crankshaft speed. The arrangement consists of an exterior and interior drum, the interior drum being eccentric to the exterior one. Instead of the usual single vane running right through the interior drum as used in gas exhausters, the Malbay compressor is fitted with six vanes. These vanes work in and out in slots in the interior drum, and, under the influence of centrifugal force, they fly outwards and make contact with the inner surface of the exterior drum, being pushed back into their slots at the bottom of their revolution, where the surface of the eccentric drum approaches the inner surface of the exterior drum. The inlet and outlet ports are situated in the end cover plates of the blower.
The Malbay generator is fitted with a hand starting fan, but the usual practice is to start up on petrol and to turn over to gas after a few minutes' running.
We had an opportunity recently of witnessing the ease with which the Malbay apparatus can be started. Our visit to
the Malbay works was quite unexpected, and when we arrived a De Dion-Bouton stationary electric lighting set was about to be run for the first time on charcoal gas. The generator was new and untried, and the final pipe connections were being Made. We timed the start carefully, and from the moment when the engine was started up on petrol to the mo'tient when the inlet from the carburetter was closed and the gas cock opened exactly 4 minutes elapsed. In 41 minutes the lighting set was giving its maximum output of 50 amps. at 115 volts. The generator furnace was lighted by means
of an oily rag, about a minute after the engine had been started up on petrol.
The extreme steadiness of running under gas made a very favourable impression, and here the forced induction arrangement undoubtedly showed to be of great assistance. In its first experimental form, the Malbay apparatus was rather cumbersome, but in its latest commercial form it is smaller and more compact than the average portable gasproducer for automobile work. The Malbay should have a successful future overseas. It is made by It. Malbay, 122, Faubourg St. Martin, Paris.