Mance: Quarry Industry of Southern Indiana 



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The air blast is heated by an economizer which receives its heat 

 from the hot gases as they leave the producer. The storage of 

 the gas before it is used in the engine makes it possible to re- 

 move tar or other impurities, and hence bituminous coals, lignite, 

 or peat can be used. 



In the down-draft producer the gases are drawn downward 

 thru the coal bed instead of upward as in the other types. In 

 this way the tar and tarry vapors which would distill off of the 

 new coal as it is fed to the fire are drawn down into the hot fuel 

 bed and burned into fixed gases which can be delivered to the 

 engine in gaseous form. The down-draft producer is well adapted 

 to bmming low-grade coals in which the loss of the tar would be 

 serious. In large installations where by-products recovery is 

 practicable, the other types can successfully compete with the 

 down-draft type. 



I will not attempt here to go into the details of construction 

 of the different types of gas producers. The development of the 

 gas producer has been rapid and there is already an extensive 

 hterature of the subject. The work of the United States Bureau 

 of Mines on the gas producer and its development in this country 

 has done much to give us a better imderstanding of its operation. 

 The following publications of the U. S. Bureau of ]\Iines, Wash- 

 ington, D.C., treat of various phases of the producer-gas problem 

 and are for free distribution: namely. Bulletins 4, 7, 13, and 31, 

 and Technical Papers 9 and 20. 



Producer-gas installations in the United States at the present 

 time number over 1.000, ranging in power from 15 horse-power 

 up to several thousand. The total horse-power is over 300,000. 

 During the period from 1909 to 1912 the nimiber of producer-gas 

 plants of over 500 horse-power rating which were using bituminotis 

 coal increased 118 per cent and the toal horse-power increased 

 89 per cent. 



Producer gas is in reality a mixture of gases, and may be 

 classed under the three following heads: air gas, mixed gas, water 

 gas. The first of these results when the gas producer is blown 

 with, dry air: mixed gas results when the producer is blown 

 alternately with air and steam; and when the producer is blown 

 with steam, water gas results. In all cases the amount of car- 

 bon in the coal is the factor that chiefly determines the value of 

 the gas. The incomplete combustion of a pound of carbon into 

 carbon monoxide yields 4,450 B.T.U.. and the gas formed carries 

 with it to the engine the additional 10,231 B.T.U. that would 



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