Part 27 (1/2)

VALUE OF ONE POUND OF MILL BAGassE AT DIFFERENT EXTRACTIONS

1: Per Cent Extraction of Weight of Cane 2: Per Cent Moisture in Bagasse 3: Per Cent in Bagasse 4: Fuel Value, B t u

5: Per Cent in Bagasse 6: Fuel Value, B t u

7: Per Cent in Bagasse 8: Fuel Value, B t u

9: Total Heat Developed per Pound of Bagasse 10: Heat Required to Evaporate Moisture[42]

11: Heat Available for Steaasse Equivalent to one Pound of Coal of 14,000 B t u

+----------------------------------------------------------------+ |+---+-----+----------+---------+---------+----------------+----+| || | | | | |Btu Value per| || || | | Fiber | Sugar |Molasses |Pound of Bagasse| || || | +-----+----+----+----+----+----+-----+----+-----+ || || | | | | | | | | | | | || || 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 || |+---+-----+-----+----+----+----+----+----+-----+----+-----+----+| || BASED UPON CANE OF 12 PER CENT FIBER AND JUICE CONTAINING || ||18 PER CENT OF SOLID MATTER REPRESENTING TROPICAL CONDITIONS || |+---+-----+-----+----+----+----+----+----+-----+----+-----+----+| ||75 |4264|4800|3996|624|451 |312|217 |4664 |525 |4139 |338|| ||77 |3922|5217|4343|574|414 |287|200 |4958 |483 |4475 |313|| ||79 |3515|5714|4757|514|371 |257|179 |5307 |433 |4874 |287|| ||81 |3021|6316|5258|442|319 |221|154 |5731 |372 |5359 |261|| ||83 |2412|7059|5877|353|256 |176|122 |6255 |297 |5958 |235|| ||85 |1620|8000|6660|240|173 |120| 83 |6916 |200 |6716 |208|| |+---+-----+-----+----+----+----+----+----+-----+----+-----+----+| || BASED UPON CANE OF 10 PER CENT FIBER AND JUICE CONTAINING || ||15 PER CENT OF SOLID MATTER REPRESENTING LOUISIANA CONDITIONS|| |+---+-----+-----+----+----+----+----+----+-----+----+-----+----+| ||75 |5100|4000|3330|600|433 |300|209 |3972 |678 |3294 |425|| ||77 |4807|4345|3617|566|409 |282|196 |4222 |592 |3630 |386|| ||79 |4452|4762|3964|524|378 |262|182 |4524 |548 |3976 |352|| ||81 |4018|5263|4381|473|342 |236|164 |4887 |495 |4392 |319|| ||83 |3500|5882|4897|412|298 |206|143 |5436 |431 |5005 |280|| ||85 |2833|6667|5550|333|241 |167|116 |5907 |349 |5558 |252|| |+---+-----+-----+----+----+----+----+----+-----+----+-----+----+| +----------------------------------------------------------------+

Furnace Design and the Coar manufacture there caasse available for fuel As the general efficiency of a plant of this description is measured by the amount of auxiliary fuel required per ton of cane, the relative i of this fuel is apparent

In modern practice, under certain conditions of asse of certain physical properties, the bagasse available froround will meet the total steam requirements of the plant as a whole; such conditions prevail, as described, in Java In the United States, Cuba, Porto Rico and like countries, however, auxiliary fuel is al to a great extent upon the proportion of fiber in the cane, which varies widely with the locality and with the age at which it is cut, and to a lesser extent upon the degree of purity of the ar, the use of the maceration water and the efficiency of the27 Babcock & Wilcox Boiler Set with Green Bagasse Furnace]

Experience has shown that this fuel iven aasse burned in one furnace between two boilers will give better results than the same quantity burned in a nuainst such practice on the grounds that the necessity of shutting doo boiler units when it is necessary for any reason to take off a furnace, requires a larger combined boiler capacity to insure continuity of service As a matter of fact, several se furnace, and the saving in original furnace cost by such an installation, taken in conjunction with the added efficiency of the larger furnace over the small, will probably more than offset the cost of additional boiler units for spares

The essential features in furnace design for this class of fuel are aas travel sufficient to enable the gases to be co surfaces are encountered Experience has shown that better results are secured where the fuel is burned on a hearth rather than on grates, the objection to the latter ely around the edges, where the fuel pile is thinnest When burned on a hearth the air for coh several rows of tuyeres placed above and syerate, and a proper ely the objection to grates and at the same time enable other fuel to be burned in the furnace when necessary This arrangerates and tuyeres is probably the better from a commercially efficient standpoint Where the air is adrate or hearth line, it ies on the fuel pile as a whole and causes a uniform combustion

Such tuyeres connect with an annular space in which, where a blast is used, the air pressure is controlled by a blower

All experience with this class of fuel indicates that the best results are secured with high combustion rates With a natural draft in the furnace of, say, three-tenths inch of water, a corate surface per hour may be obtained With a blast of, say, five-tenths inch of water, this rate can be increased to 450 pounds per square foot of grate surface per hour

These rates apply to bagasse as fired containing approximately 50 per cent of moisture It would appear that the most economical results are secured with a combustion rate of approximately 300 pounds per square foot per hour which, as stated, may be obtained with natural draft

Where a natural draft is available sufficient to give such a rate, it is in general to be preferred to a blast

Fig 27 shows a typical bagasse furnace hich very satisfactory results have been obtained The design of this furnace may be altered to suit the boilers to which it is connected It htly in its proportions and in certain instances in its position relative to the boiler The furnace as shown is essentially a bagasse furnace and may be modified sonited in a pit A on a hearth which is ordinarily elliptical in shape Air for coh the tuyeres B connected to an annular space C through which the amount of air is controlled Above the pit the furnace widens out to form a combustion space D which has a cylindrical or spherical roof with its top ordinarily froases pass from this space horizontally to a second coh arches F to the boiler The arrangement of such arches is modified to suit the boiler or boilers hich the furnace is operated A furnace of such design embodies the essential features of aas travel

The fuel should be fed to the furnace through an opening in the roof above the pit by some mechanical means which will insure a constant fuel feed and at the same time prevent the inrush of cold air into the furnace

This class of fuel deposits a considerable quantity of dust, which if not relass-like clinker Ample provision should be as ducts and the boiler setting, and these should be thoroughly cleaned once in 24 hours

Table 45 gives the results of several tests on Babcock & Wilcox boilers using fuel of this character

TABLE 45

TESTS OF BABcock & WILcox BOILERS WITH GREEN BAGassE ____________________________________________________________________ | Duration of Test | Hours | 12 | 10 | 10 | 10 | | Rated Capacity of Boiler |Horse Power| 319 | 319 | 319 | 319 | | Grate Surface |Square Feet| 33 | 33 | 165 | 165 | | Draft in Furnace | Inches | 30 | 28 | 29 | 27 | | Draft at Damper | Inches | 47 | 45 | 46 | 48 | | Blast under Grates | Inches |||| 34 | | Terees F| 536 | 541 | 522 | 547 | | /CO_{2} | Per Cent | 138 | 126 | 117 | 128 | | Flue Gas analysis { O | Per Cent | 59 | 76 | 82 | 69 | | CO | Per Cent | 00 | 00 | 00 | 00 | | Bagasse per Hour as Fired | Pounds | 4980 | 4479 | 5040 | 5586 | | Moisture in Bagasse | Per Cent |5239 |5293 |5184 |5171 | | Dry Bagasse per Hour | Pounds | 2371 | 2108 | 2427 | 2697 | | Dry Bagasse per Square Foot| | | | | | | of Grate Surface per Hour| Pounds | 719 | 639 |1471 |1634 | | Water per Hour frorees | Pounds |10141 | 9850 |10430 |11229 | | Per Cent of Rated Capacity | | | | | | | Developed | Per Cent | 921 | 892 | 947 |1020 | |____________________________|___________|______|______|______|______|

Tan Bark--Tan bark, or spent tan, is the fibrous portion of bark re industry It is usually very high in its e of 65 per cent or about two-thirds of the total weight of the fuel The weight of the spent tan is about 213 tiround In calorific value an average of 10 saives 9500 B t u

per pound dry[43] The available heat per pound as fired, owing to the great percentage of moisture usually found, will be approxiht of the spent tan as fired is 213 as great as the weight of the bark as ground at the round bark produces an available heat of approximately 5700 B t u Relative to bituminous coal, a ton of bark is equivalent to 04 ton of coal An average cheen 604, oxygen 4074, ash 142

Tan bark is burned in isolated cases and in general the re ood fuel apply to its coe co to the fuel bed, and draft sufficient for high cos obtainable with this class of fuel will not be as high as ood fuel, because of the heat value and the excessive moisture content Mr D M Meyers found in a series of experie of from 15 to 208 horse power could be developed per square foot of grate surface with horizontal return tubular boilers This horse poould vary considerably with the method in which the spent tan was fired