TRIALS OF VARIOUS TYPES OF MARINE  BOILERS

Grate Heating Surface burned in Stoke- Draught- Per jb. of coal. ated per Thermal of Description of Boiler . Area of Trial per sq. ft. hold- Inches of sq. ft. of Units per Boiler sq. ft. sq. ft . Hours. of Grate Inches of Water . Heating jb of Coal . 7Jo per Hour. water . Actual . From and Surface . at 212° F . lb. lb . 115 . Ordinary cylindrical single- 81 2308 25 14.2 Nil 0.36 8.56 10.26 4.26 14,267 69.7 ended; 3 furnaces; 155 lb „ „ 24 13.9 0.50 8'84 10.33 4'32 14,697 68•o working pressure; closed „ 9 30.3 o•81 0.39 7.93 9.27 8.46 14,686 61.4 stokehold system ' ,, „ 8a 29•I 0.65 0.32 8.84 10.34 9'05 14,612 68.4 Ordinary cylindrical single- 2876 in boiler, In Ash- ended; 3 furnaces; 210 lb 63.2 66 in air 13 20.6 pit 0.58 11.30 12.33 5.14 14,475 82.3 ashpit, Howden system working pressure; closed" heaters 1'53 Niclausse water-tube; 160 lb 46 1322 8 12.8 Nil 0.20 8.41 10.15 3.75 14,680 66.9 working pressure 8 21.9 „ 0.20 8•oi 9.40 6.11 14,760 62.1 37 20.2 0.29 7.62 9.00 5.44 14,600 60.5 34 990 9 14.0 0.10 0.23 8.77 10.50 4.17 14,640 69.8 Niclausse water-tube; 250 lb „ „ 9 22.0 0.27 0.23 7.68 9.06 5.74 14,640 60.4 working pressure 90 15.4 Nil Not ascer- 7.61 9.08 4.00 14,630 59'9 Babcock water-tube; ' in . tubes; 260 lb working r 36 Iwo 9 13.0 „ 0.26 9.31 I1.02 4.30 14,590 73.2 3ifi J 9 20.0 o•18 0.20 8.58 IOII 6.13 14590 67.0 tained pressure 90 14 5 Nil Not ascer- 8 09 9'53 4,18 63.1 tained 62 2167 28 18.4 „ 0.45 8.94 Io.61 4.61 14,520 70.7 24 19'2 „ 0.47 8.93 10'59 4.82 14,390 71.1 Babcock water-tube; I fa in .

12 20.5 0.42 9'42 11.04 5.41 14,080 75.8 tubes; 270 lb working 7 28.9 0•'50 Not ascer- 8.54 9.88 6.91 14,390 66.3 pressure tained 30 19.9 Nil 0.38 10•11 12.00 6•o1 14530 79.9 29 27.I o•66 0.23 9.96 11.67 8.05 14,630 77.1

Belleville water-tube with ( 44 910 in boiler 24a I5.8 Nil 0.36 9.65 II.46 4'94 14,697 77'2 economizers; 320 lb j " 447 in econo- 24 17.4 „ 0.39 9.33 I I.00 5.30 14,805 71.8 working pressure l „ miter; II 19.8 „ 0.43 9'39 11'03 6'38 14,578 73'3 ,, 1357 total 8 27.2 „ 0.39 8'28 9.79 7.78 14,611 65.0 56 2896 26 16.9 0.31 9.57 IT .45 3.12 14,750 75.0 26 18.2 „ 0.31 9.37 11.33 3.30 14,500 75.7 Yarrow water-tube; 14 in . „ „ 25 21.3 0.31 8.83 10.45 3.63 13,500 75.2 tubes; 250 lb working .. 30 35.4 0.53 0.26 8.82 10.59 6.04 14,430 70.9 pressure 8 41.9 0.86 0.31 8.24 9'94 6.69 14,500 66.3 8 33.7 0.31 0.30 8.39 9.93 5.47 14,680 65.4 8 39.8 0.82 0.24 8.85 10.43 6.81 14,530 69.5 71 26 16.1 Nil 0.39 7.95 9.50 3.24 14,500 63.8 26 17.7 „ 0.30 7.06 9.28 3.43 14,620 61.7 „ 2671 in boiler, 25 21.1 0.31 7.62 9.08 4.05 14,650 60:3 Durr water-tube; 250 lb „ 140 in super- 7 33.8 0.70 0.36 7.72 9'29 6.59 14,570 62.7 working pressure heater; -i 8 26.7 0.33 0.35 7.86 9.26 5.30 14,320 63.1 g p „ 2811 total I 8 34.6 I•II 0.20 8•o2 9.53 7.02 14,230 64.8 22 34.8 0.73 o•,6 6.84 8•o6 6.02 14,430 54'0 24 29'9 0.35 0.12 7.62 9.00 5.75 14,240 61.2 • . 20 19.9 Nil 0.21 7.30 8'33 3.66 14,240 58.6 ' In the first three trials no retarders were used in the tubes . In the last trial retarders were used . 2 In this trial retarders were used in the tubes . ' The first four trials were made with horizontal baffles above the tubes; the last two trials with the baffling described in the text . to represent the bulk of the coal used during the trial . The periodic records taken are the weights of the fuel used and of the ashes, &c., produced, the temperature and quantity of the feed-water, the steam pressure maintained, and the wetness of the steam produced . This last should be ascertained from samples taken from the steam pipe at a position where the full pressure is maintained . In order to reduce to a common standard observations taken under different conditions of feed temperatures and steam pressures, the results are calculated to an equivalent evaporation at the atmospheric pressure from a feed temperature of 212° F . (J .

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