Part 29 (1/2)

Fro burners, individual burners have not as large a capacity as the stea class In some tests on a Babcock & Wilcoxburners, the maximum horse power developed per burner was approxiely one of proper relation between furnace volun--Too n for the use of this class of fuel Provided a good type of burner is adopted the furnace arrange air for combustion into the furnace are the all important factors No matter what the type of burner, satisfactory results cannot be secured in a furnace not suited to the fuel

The Babcock & Wilcox Co has hadof oil as fuel and an extended series of experiments by Mr E H Peabody led to the develop29 shows such a furnace applied to a Babcock & Wilcox boiler, and with slight modification it can be as readily applied to any boiler of The Babcock & Wilcox Co

manufacture In the description of this furnace, its points of advantage cover the requireeneral

The atomized oil is introduced into the furnace in the direction in which it increases in height This increase in furnace volume in the direction of the flah mixture of the oil with the air, and the consequent coases before they co surfaces In such a furnace flat flame burners should be used, preferably of the Peabody type, in which the flame spreads outward toward the sides in the fore directly on the heating surfaces, and the furnace can handle any quantity of flaer of tube difficulties The burners should be so located that the flae to any extent on the side walls of the furnace, an even distribution of heat being secured in this manner The burners are operated froh which the operatorthe burners The burners can be removed, inspected, or cleaned and replaced in a few h a checkerwork of fire brick supported on the furnace floor, the openings in the checkerwork being so arranged as to give the best econo 29 Babcock & Wilcox Boiler, Equipped with a Peabody Oil Furnace]

With steah the front of the boiler in stationary practice, it is usually in the direction in which the furnace decreases in height and it is with such an arrangeh the loss of tubes ee directly upon the tube surfaces and tube troubles from this source may arise, particularly where the feed water has a tendency toward rapid scale formation Such difficulties may be the result of a blowpipe action on the part of the burner, the over heating of the tube due to oil or scale within, or the actual erosion of the metal by particles of oil improperly atomized Such action need not be anticipated, provided the oil is burned with a short fla burners have a less velocity of projection than those froher end of the furnace, should not lead to tube difficulties provided they are properly located and operated This class of burner also will give the most satisfactory results if introduced so that the flames travel in the direction of increase in furnace voluood results secured withburners and Babcock & Wilcox marine boilers in which, due to the fact that the boilers are fired froh the front are in this direction

Operation of Burners--When burners are not in use, or when they are being started up, careon the floor of the furnace before it is ignited In starting a burner, the ato wad of oil-soaked waste held before it on an iron rod To insure quick ignition, the steam supply should be cut down But little practice is required to beconition has taken place and the furnace brought to an even heat, the steam should be cut down to the minimum amount required for atomization This amount can be determined from the appearance of the fla oil will drop to the furnace floor, giving a scintillating appearance to the flame The steam valves should be opened just sufficiently to overco action

Air Supply--Fro, the quantity of air for combustion may be minimized As with other fuels, when the amount of air admitted is the minimum which will completely consume the oil, the results are the best The excess or deficiency of air can be judged by the appearance of the stack or by observing the gases passing through the boiler settings A perfectly clear stack indicates excess air, whereas sned furnaces the best results are secured by running near the sht variation in the air supply will affect the furnace conditions in an oil burning boiler more than the same variation where coal is used, and for this reason it is of the utas analysis beboilers With the air for coulated by adjustment of any checkerwork or any other device which as analysis should show, for good furnace conditions, a percentage of CO_{2} between 13 and 14 per cent, with either no CO or but a trace

In boiler plant operation it is difficult to regulate the steam supply to the burners and the damper position to meet sudden and repeated variations in the load A device has been patented which autoulates by means of the boiler pressure the pressure of the steam to the burners, the oil to the burners and the position of the boiler daood results in plant operation where hand regulation is difficult at best, and in many instances is unfortunately not even attempted

Efficiency with Oil--As pointed out in enuher efficiencies are obtainable with the former With boilers of approxined furnaces and burners, an efficiency of 83 per cent is possible oran allowance of 2 per cent for steam used by burners, a net efficiency of 81 per cent The conditions under which such efficiencies are to be secured are distinctly test conditions in which careful operation is a prime requisite With furnace conditions that are not conductive to the best coure e properly designed plants, however, the first na conditions, the nearness to which it is reached depending on the intelligence of the operating crew It must be remembered that the use of oil fuel presents to the careless operator possibilities for wastefulness reater than in plants where coal is fired, and it therefore pays to go carefully into this feature

Table 48 gives some representative tests with oil fuel

TABLE 48

TESTS OF BABcock AND WILcox BOILERS WITH OIL FUEL

_______________________________________________________________________ | | | | | | |Pacific Light|Pacific Light|Miami Copper | | | and Power | and Power | Coeles, | | Miami, | | | Cal |Redondo, Cal| Arizona | |_____________________________|_____________|_____________|_____________| | | | | | | | Rated Capacity | Horse | | | | | of Boiler | Power | 467 | 604 | 600 | |__________________|__________|_____________|_____________|_____________| | | | | | | | | | | Duration of Test | Hours | 10 | 10 | 7 | 7 | 10 | 4 | | | | | | | | | | | Steae | Pounds | 1564| 1569| 1847| 1849| 1834| 1895| | | | | | | | | | | Terees | | | | | | | | Feed Water | F | 626| 611| 934| 1012| 1577| 1566| | | | | | | | | | | Degrees of | Degrees | | | | | | | | Superheat | F | | | 837| 1443| 1034| 1396| | | | | | | | | | | Factor of | | | | | | | | | Evaporation | |12004|12020|12227|12475|11676|11886| | | | | | | | | | | Draft in Furnace | Inches | 02 | 05 | 014| 19 | 12 | 22 | | | | | | | | | | | Draft at Damper | Inches | 08 | 15 | 046| 47 | 19 | 67 | | | | | | | | | | | Terees | | | | | | | | Exit Gases | F | 438 | 525 | 406 | 537 | 430 | 612 | | _ | | | | | | | | | Flue | CO_{2} | Per Cent | | | 143 | 121 | | | | Gas | O | Per Cent | | | 38 | 68 | | | | analysis|_CO | Per Cent | | | 00 | 00 | | | | | | | | | | | | | Oil Burned | | | | | | | | | per Hour | Pounds | 1147 | 1837 | 1439 | 2869 | 1404 | 3214 | | | | | | | | | | | Water Evaporated | | | | | | | | | per Hour from | | | | | | | | | from and at | Pounds | 18310| 27855| 22639| 40375| 21720| 42863| | 212 Degrees | | | | | | | | | | | | | | | | | | Evaporation frorees per | Pounds | 1596| 1516| 1573| 1407| 1547| 1334| | Pound of Oil | | | | | | | | | | | | | | | | | | Per Cent of | | | | | | | | | Rated Capacity | Pounds | 1136| 1729| 1086| 1938| 1049| 2071| | Developed | | | | | | | | | | | | | | | | | | B t u per | | | | | | | | | Pound of Oil | B t u | 18626| 18518| 18326| 18096| 18600| 18600| | | | | | | | | | | Efficiency | Per Cent | 8315| 7946| 8329| 7602| 8070| 696 | |__________________|__________|______|______|______|______|______|______|

Burning Oil in Connection with Other Fuels--Considerable attention has been recently given to the burning of oil in connection with other fuels, and a combination of this sortthe boiler capacity to assist over peak loads, or to keep the boiler in operation where there is the possibility of a temporary failure of the primary fuel It would appear froives satisfactory results from the standpoint of both capacity and efficiency, if the two fuels are burned in separate furnaces Satisfactory results cannot ordinarily be obtained when it is attempted to burn oil fuel in the same furnace as the primary fuel, as it is practically impossible to admit the proper amount of air for combustion for each of the two fuels simultaneously The Babcock & Wilcox boiler lends itself readily to a double furnace arrange 30 shows an installation where oil fuel is burned as an auxiliary to wood

[Illustration: Fig 30 Babcock & Wilcox Boiler Set with Coas Tar--Water-gas tar, or gas-house tar, is a by-product of the coal used in the htly heavier than crude oil and has a co, it should be heated only to a temperature which makes it sufficiently fluid, and any furnace suitable for crude oil is in general suitable for water-gas tar Care should be taken where this fuel is used to install a suitable apparatus for straining it before it is fed to the burner

[Illustration: Babcock & Wilcox Boilers Fired with Blast Furnace Gas at the Bethlehem Steel Co, Bethlehem, Pa This Company Operates 12,900 Horse Power of Babcock & Wilcox Boilers]

GASEOUS FUELS AND THEIR COMBUSTION

Of the gaseous fuels available for steaas, natural gas and by-product coke oven gas

Blast furnace gas, as implied by its name, is a by-product froasification of the solid fuel in a blast furnace results, 1st, through coh contact with the incandescent ore (Fe_{2}O_{3} + C = 2 FeO + CO and FeO + C = Fe + CO); and 3rd, through the agency of CO_{2} either formed in the process of reduction or driven froed either as ore or flux

Approximately 90 per cent of the fuel consumed in all of the blast furnaces of the United States is coke The consumption of coke per ton of iron made varies from 1600 to 3600 pounds per ton of 2240 pounds of iron This consumption depends upon the quality of the coal, the nature of the ore, the quality of the pig iron produced and the equipe consumption, and one which is approximately correct for ordinary conditions, is 2000 pounds of coke per gross ton (2240 pounds) of pig iron The gas produced in a gas furnace per ton of pig iron is obtained froen coht of the gaseous constituents of the flux and the weight of air delivered by the blowing engine and the weight of volatile coht of gas will be found to be approxiht of the coke burned, or 10,000 pounds per ton of pig iron produced

With the exception of the sen as en, ordinarily less than 01 per cent, the calorific value of blast furnace gas is due to the CO content which when united with sufficient oxygen when burned under a boiler, burns further to CO_{2} The heat value of such gas will vary in most cases from 85 to 100 B t u per cubic foot under standard conditions In modern practice, where the blast is heated by hot blast stoves, approxias is used for this purpose, leaving 85 per cent of the total for use under boilers or in gas engines, that is, approxi iron produced In a as serves ordinarily as the only fuel required Table 49 gives the analyses of several saas

TABLE 49