THE ROTARY KILN. 



489 



cement apparatus, which have a tendency to heat large volumes of 

 air by means of the galvanized steel ducts, thus insuring air at a much 

 higher temperature for use as blast to the injector. The air-blast of 

 fans is distributed to the several injectors by means of galvanized steel 

 piping J, usually located directly in back of injectors. 



The pulverized coal as it drops into injector is taken into suspen- 

 sion by air-blast supplied to injector through blast-piping J and 

 fed through wrought-iron feed-pipes K into discharge end of kiln. 

 The feed-pipe usually enters kiln about 3 to 12 inches below the center. 



FIG. 123. Kirkwood gas-burner for rotary kiln. 



In extremely large kilns two feed-pipes are usually used so that cur- 

 rent of air containing the pulverized coal can be blown into different 

 points of the kiln at the same time. The volume of air admitted to 

 injector is regulated by blast-gate L. The length of the flame in the 

 kiln is dependent upon the velocity of the air as it leaves the feed-pipe. 

 Gas-burners for rotary kilns. Natural gas is at present utilized 

 as a kiln fuel at several Kansas plants. An Ohio plant when last visited 



