1917] RURAL ENGINEERING. 685 



trical contact and the pressure is read on a pressure gage. Typical calibration 

 results are given. 



Tests of boilers with bagasse as fuel, E. W. Kerb (Louisiana Stas. Bui. 160 

 {1916), pp. 58, figs. 5).— Continuing work previously noted (E. S. R., 22, p. 115), 

 data are presented obtained from several series of boiler tests made at sugar 

 factories during the grinding seasons of 1909, 1910, 1914, and 1915. The general 

 purpose of these tests was to study the fuel economy of bagasse as affected by 

 varying the size and form of the combustion chamber, the air supply, the amount 

 of overload, and the size of grate. 



In 1909 twenty tests were made in five sugar factories, seventeen of which 

 were on bagasse-burning boiler plants and the remaining three on oil-burning 

 plants. The first plant has one 300-horsepower Stirling boiler with 3,000 sq. 

 ft. of heating surface for bagasse and four 125-horsepower horizontal return 

 tubular boilers for oil. The second factory has eight horizontal return tubular 

 boilers for bagasse, making a total of 9,097 sq. ft. of heating surface and 

 giving 758 horsepower. The third factory has four horizontal return tubular 

 boilers for bagasse, each having 1,260 sq. ft. of heating surface, making a total 

 of 421 horsepower. The fourth factory has nine boilers for bagasse, having 

 a total of 16,600 sq. ft. of heating surface and a capacity of 1,383 horsepower. 

 The fifth factory has five internally fired boilers with a total of 1,500 horse- 

 power. All the bagasse boilers have Dutch oven furnaces. 



The tests on these plants showed that decreasing the load on heavily over- 

 loaded boilers resulted in increased economy. Little change in economy could 

 be produced by attempts to reduce the air supply by closing the ash pit doors 

 or the fuel hopper doors. However, regulation of the draft by means of 

 the stack damper resulted in a substantial increase in economy. An increase 

 in evaporation of 26 per cent resulted from halving the furnace draft In a 

 plant having a very high chimney by partially closing the flue dampers. The 

 best fuel economy was found in furnaces having the highest temperatures. 

 The highest furnace temperatures were invariably in the furnaces having the 

 highest rates of combustion and the highest carbon dioxid content in flue 

 gases. The power development by the boilers with bagasse as fuel varied 

 from 0.89 to 1.12 horsepower per ton of cane per 24 hours, the average being 

 1.02. The total power development in the plant burning oil and bagasse to- 

 gether was 1.8 horsepower per ton of cane per 24 hours. 



In 1910 a series of tests was made in connection with experiments on the 

 question of bagasse drying. The tests were all made on a Stirling boiler with 

 1,000 sq. ft. of heating surface. It was found in these tests that boiler efficiency 

 is lowered by excessive draft. Forced draft gave higher efficiency than stacked 

 draft. This is attributed to the fact that the blower causes reduced vacuum 

 in the furnace and consequently less inleakage of air. The stack heat loss 

 was very high, the average being 45.16 per cent. 



In 1914 and 1915 tests were made for the purpose of securing data regarding 

 the effect of rate of combustion, volume of combustion chamber, form of com- 

 bustion chamber, methods of feeding bagasse, and leakage of air into the 

 setting upon boiler efficiency. Special attention was also given to the question 

 of flue gas analysis. The tests were made upon four typical bagasse boilers 

 and settings. 



It was found that no particular advantage was indicated in tests of a 

 boiler with a combustion space of unusual size and form. Higher efficiencies 

 were obtained with a boiler having a much smaller combustion space. The 

 highest efficiencies were obtained with higher rates of combustion. The high- 

 est rate of combustion obtained in any of the tests was 225 lbs. of bagasse per 

 square foot of grate surface per hour in a setting with a large combustion 



