GASEOUS FUELS 



105 



current of air is then forced or drawn through the red-hot 

 fuel. At the bottom of the producer, the oxygen of the air 

 forms carbon dioxide. As this rises through the fuel bed, 

 it gives up a part of its oxygen to carbon, thus forming the 

 carbon monoxide which escapes through the exit to the engine 

 or furnace. 



Now since the carbon in the producer is burned to carbon 

 monoxide only, it therefore liberates about 30 per cent, of its 

 energy. This serves to keep the fuel bed hot. In fact, the 

 temperature would soon rise too high for successful working. 

 In order to keep the temperature down and yet not waste 

 heat energy, a jet of steam is introduced into the producer. 

 As it rises through the red-hot bed of coal, the steam is de- 

 composed, liberating hydrogen, while the oxygen of the 

 steam unites with carbon to form more carbon monoxide 

 exactly as in the manufacture of water-gas. Heat is ab- 

 sorbed during this change. The hydrogen and the carbon 

 monoxide resulting are also delivered through the exit pipe 

 and are used as fuel. 



Producer gas differs from water-gas in that it contains all of 

 the nitrogen that was in the air used to feed the producer. 

 Since the nitrogen neither burns nor supports combustion, 

 the producer gas has a lower heat-producing ability than any 

 of the other gases mentioned. 



TABLE IV. COMPOSITION OF GASEOUS FUELS (APPROXIMATE) 



