BOILEE No. 7. 85 



Dimensions of Boiler No. 7. 



Diameter of each shell, 60 in. 



Length between heads and length of tubes, . . . 15 ft. 

 Number of tubes ( collective ; 3 1-2 inches outside diameter, 348 



Area of heating surface, 5,646 sq. ft. 



Area of grate surface, 150 sq. ft. 



Area through tubes, . . . . . . 20 sq. ft. 



Height of chimney, 150 ft. 



Width of air spaces and metal bars in grates, . . . 3-8 in. 



Ratio of heating surface to grate surface, . . . 37.6 to 1 



Eatio of grate surface to tube area, 7.5 to 1 



Eesults of Tests. ( Two days. ) Boiler No. 7. 



Test No. 13. 

 Manner of start and stop and kind of run, .... Ordinary. 



Duration, 13.5 hrs. 



Coal consumed, dry ( including wood equivalent ),. . 20,476 Ibs. 



Percentage of ash, 14.2 percent. 



Water evaporated, 163,705 Ibs. 



Coal per hour, 1,516.7 Ibs. 



Coal per hour per square foot of grate, . . . . 10 1 Ibs. 



Water per hour, . . 12,125.9 Ibs. 



Water per hour per square foot of heating surf ace, . 2.1 Ibs. 



Horse-power developed, 404.2 H. P. 



'Boiler pressure, 86 Ibs. 



Temperature of feed-water, 102 deg. 



Temperature of escaping gases, 410 deg. 



Water per pound of coal, 7.90 Ibs. 



Water per pound of coal from and at 212 degrees, . . 9.18 Ibs. 



Water per pound of combustible from and at 212 degrees, 10.70 Ibs. 

 NOTE. The coal when fired contained 5 per cent, of water. 



The results of the test on Boiler No. 7 furnish an example 

 of the performance of a low grade of fuel in a large plant of 

 new boilers, where the conditions were favorable for obtaining 

 a good result. The evaporation per pound of coal compares 

 favorably with that produced in many cases with the best 

 grades of anthracite coal, and this is all that could be desired 

 from fuel composed largely of screenings. In this case the 

 screenings were evidently of good quality. 



