US2882612A - Apparatus for driving off moisture from sugar-cane bagasse - Google Patents

Description

April 21, 1959 s. l. GONZALEZ APPARATUS FOR DRIVING OFF MOISTURE FROM SUGAR-CANE BAGASSE Filed Aug. 28, 1956 r 5 Sheets-Sheet 1 [/v VENTOR.

A TTORNEYJ,

April 21, 1959 s. l. GONZALEZ 2,882,612

I APPARATUS FOR DRIVING OFF MOISTURE FROM SUGAR-CANE BAGASSE Filed Aug. 28, 1956 5 Sheets-Sheet 2 gas GOO 000 o g- 000 oocfi ooo 0 ooo 0oo 2000 i 000; oooqooo QI RQ figg gl 0 00 c500 000-- QQT 0 O 13 M I vf/ vroxz: 'W

ATTORNEYS.

April 21, 1959 s. l. GONZALEZ APPARATUS FOR DRIVING OFF MOISTURE FROM SUGAR-CANE BAGASSE Filed Aug. 28 1956 5 Sheets-Sheet 3 MM Bywa g VEENTORJ ATTORNEYS.

April 1959 s. l; GONZALEZ 2,882,612

APPARATUS FOR DRIVING OFF MOISTURE FROM SUGAR-CANE BAGASSE Filed Aug. 28, 1956 5 Sheets-Sheef4 [N VEINTOR:

A TTORNEYSA April 21, 1959 s. l. GONZALEZ 2,332,612

APPARATUS FOR DRIVING OFF MOISTURE FROM SUGAR-CANE BAGASSE 5 Sheets-Sheet 5 Filed Aug. 28, 1956 f/VVE/V 702' A TTORNE r iinited rates Patent APPARATUS FOR DRIVING OFF MGISTURE FROM SUGAR-CANE BAGASSE Santos Inclan Gonzalez, Hershey, Cuba Application August 28, 1956, Serial No. 606,695

3 Claims. (Cl. 3486)- This invention relates to the utilization ofsugar-cane bagasse as a fuel for the boiler-house furnaces of a sugar factory, and it has for itsobject to provide a method for driving off moisture from bagasse with a view to increasing the bagasse calorific value when it is burned.

The method of. this invention consists in heating the bagasse as it leaves the mills by means ofthevery combustion gases issuing to the atmosphere through the. fac tory chimney and by means of cold air that is heated by the combustion gases, allowing the bagasse to fallby gravity through vertical tubes exteriorly heated by com.- bustion gases and injecting heated air into said tubes to directly contact the falling bagasse, whereupon the bagasse falling through the lower opening of said tubes will be rendered completely dry. The result of burning such bagasse is to remarkably increase water evaporation in the boilers, a very important economy in fuel consumption at the boiler-house. being thereby attained.

Another object of the invention is to provide an apparatus comprising a chamber enclosed in a metal wall casing provided with a heat-insulating lining, within which are installed several series or groups of bagassegathering vertical tubes whichv are fed andv discharged by means of an endless conveyor disposed around said casing and comprising a plurality of rakes at the top portion of the conveyor. which are adapted to distribute the bagasse from the sugar-cane mills within. the bagassegathering tubes. At the bottom. portion: of the conveyor said rakes receive the dry bagasse discharged through. the gathering tubes and feed it into an inclined channel which will discharge it into suitable vehicles that will carry the bagasse to the place where it is to be burned. Within a small box at one end of said casing there is installed a series of vertical tubes having their upper ends open to the atmosphere and having connected to their lower ends a ventilator fan so that heated air will be conducted through a manifold tube and directed to a series of vertical tubes each positioned parallel to each bagassegathering tube. The vertical tubes extend into the. ba-

gasse-gathering tubes 4 distributing the heated air within.

each bagasse-gathering tube through a thinner perforated tube positioned centrally to each gathering tube. The lower ends of the perforated tubes terminate a certain height above the open bottom of each gathering tube wherein there is provided a rotatable gate for controlling the falling rate of dry bagasse, the gates of each three tubes being interconnected by means of motor-driven gears for controlling the discharge of bagasse. Within the casing there are installed two heaters, namely one heater for heating feed water for the boilers and another heater comprising two series of coil tubes disposed lengthwise of the casing. The second named heated receives water at one end of the casing to be heated and terminates at the other end in a water collector tube provided with a controlling valve to lead heated crude water to its destination.

The invention is described with reference to the figures of the accompanying drawings, of which:

Figure l is a top plan view of the apparatus of this invention, showing a casing, divided into two portions by a. longitudinal partition.

Figure 2 is a top planview of a modified form of the invention similar to that of Fig. 1, showing the casing divided into two portions by a longitudinal partition but each portion of the casing being provided with a double number of bagasse gathering tubes than those illustrated in Fig. 1.

Figure 3 is a longitudinal vertical sectional view through the apparatus of Fig. 1 on line 33 of Fig. 1.

Figure 4 is a vertical cross-sectional view on line 4-4 of Fig. 1.

Figure 5' is a detailed perspective view of three endless conveyor rakes for feeding bagasse to the bagasse-gathering tubes.

Figure 6 is a detailed perspective view of the conveyor bottom plate at its top portion, showing the inlet openings through which the bagasse is fed into the. three gathering tubes of each group as illustrated in Fig, 4.

Fig. 7 is an outer elevational view of an outerly corrugated bagasse-gathering tube.

Figure 8 is an end view of same.

Figure 9 is an outer elevational view of an outerly corrugated cold air heating tube for injecting hot air into. each bagasse gathering tube.

Figure 1.0 is an end view of same.

The present method of driving off moisture from sugarcane bagasse consists in heating the bagasse that falls vertically through one gathering tube by means of the combustion gases from the boiler furnaces, which circulates outside the gathering tube, and also heating the ba gasse by means of hot air injected into the bagasse mass by'rneans of a thin perforated tube so as to thereby fully dry the bagasse which is discharged from the gathering tube and carried to the furnaces, and which has a much greater calorific value thanv the bagasse from the mills, and to obtain an evaporation yield at the boilers that is far greater than at present obtained by directly burning the bagasse from the mills, which has a water content ofat. least 60%.

The apparatus for. carrying out the method of this invention consists of a large casing of rectangular sece tion 1 installed at the location occupied by the smoke duct 2 which leads tothe conventional chimney 3 from the furnaces 4 and is isolated by means of a gate- 5. Said casing 1 is made of steel with an inner heat.- insulating lining and its: inner space is separated from the smoke duct 2 by aligned longitudinal partitions 6- and 7 inter-spaced by an opening provided with a gate 8 and spaced apart from the ends of the casing throughfree spaces 9 and 10 adapted to allow the passage of combustion gases from the furnaces/3. The casing 1. is divided into two portions by two metallic partitions,

one longitudinal partition 11 and another transversal' partition 12 to provide. a passageway 13 at the end of tition 11 there is' installed in a narrow space a series.

of coil tubes 15 in communication through a valve 16 with a crude water supply, said tubes 15 joining at'a collector 17 provided with a control valve-18 for passing hot. crude water to the desired destination. The

space between both rows of tubes 15 is provided with: a series of pivotally connected gates 19 operable by a. handle 19' and being open as the apparatus is started,

said gates beingregulated until. thedraughtwithin the casing 1 is fully normalized.

As illustrated in Fig. 3 of the drawings, cold air heaters are installed at the ends of the spaces into which the casing has been divided by the longitudinal partition 11. Each heater comprises a lateral box 20 adjacent the casing 1 and enclosing a series of vertical tubes 21 having outer longitudinal corrugations 22 as shown in Figs. 9 and of the drawings. Said tubes 21 have their reduced top ends passing across the top wall of the casing 1 and are open to the atmosphere, whereas the reduced bottom ends of the tubes 21 pass across the bottom wall of the casing 1 and join a collector 23 which is in communication with a ventila tor fan 24 adapted to force hot air into the bagasse mass from the mills, as will be explained hereinafter. The spaces between the longitudinal partition 11 and the longitudinal vertical walls of the casing are each adapted to contain a series of three bagasse-gathering tubes 25. These tubes 25 are mounted to extend between the top and bottom walls of the casing 1 and each tube is connected to a common register box of frustro-conical shape 26. The gathering tubes shall be 3-4 meters long and 75-90 cm. in diameter, and the register boxes shall be cm. high and of a diameter sufiicient to embrace the inlets and outlets of all three gathering tubes 25. Each bagasse gathering tube has an outer longitudinal corrugation 25' and carries at its axial line a thin perforated tube 27 ending at a distance from the bottom, and a rotatable gate 28 is installed in said space, the axis of all gates being connected by a transversal shaft 29 connected by bevelled gears 30 with a longitudinal shaft 31 driven by a Mr H.P. motor having a speed reducer. Each hot air injector tube 27 has its upper end bent to extend through the bagasse tube 25 where it communicates with a heater tube 32 similarly as the previously mentioned heater tubes 21, all tubes 32 joining at a horizontal tube 33 communicating with the ventilator fan 24 for drawing in heated air and forcing it through the injector tubes 27.

An endless conveyor is installed about the casing 1 for each group of 3 bagasse-gathering tubes, which conveyor comprises two endless chains 34 and 36 mounted on sprocket wheels 35 at the corners of the casing, of which one is a motor wheel and the remainder are driven wheels. The link chains 34 and 36 carry pivotally movable rakes 38 which run on a bottom plate 39 above the entrance of the register box 26 common to each group of three gathering tubes 25, the bottom plate 39 having three large openings 40 corresponding to the tubes 25 of each group to allow the passage and gravity fall of the bagasse conveyed from the mills through an inclined channel 41. The rakes 38 are slidable on the bottom plate 39 between keepers 43.

The right top corner of the casing 1 has installed thereat a duct 43 which may be isolated by means of a gate 44 and affords communication between the easing 1 and an additional chimney 45 having three draught control ventilators 46 which may be regulated by the boiler operator. The vertical duct 13 situated beyond the vertical partition 12 has a rotatable gate 48 which may be opened when it is desired to use the convection chimney 3 or closed when it is desired to use the additional chimney 45.

Fig. 2 of the drawings illustrates a modified form of easing 1 having four series of banks of bagasse gathering tubes 25, each two series being separated by the longitudinal partition 11, which modification should be adopted for sugar factories of largest production capacity.

The operation of the apparatus is as follows: Moistened bagasse from the sugar-cane mills is discharged through the inclined channel 41 into the spaces between the rakes 38 of the endless conveyor and is distributed by said rakes 38 into the openings 40 of the gravity into three bagasse gathering tubes 25 off each group. Since the gathering tubes 25 are surrounded by the combustion gases from the furnaces 4 which circulate through and along the two spaces separated by the longitudinal partion 11, moistened bagasse falling along and within the gathering tubes 25 is indirectly heated in falling therethrough and at the same time it is heated directly by hot air injected in the bagasse mass through the perforated tubes 27 into which the air heated in tube heaters 21 is fed, the rate of fall of bagasse through the gathering tubes of each group being controlled by the rotatable gates 28. The result is that the bagasse falling through each lower register box 26 passes into the space between the rakes 38 at the lower portion of the endless conveyor to be conveyed to the inclined channel 42 and thereafter conveyed by means of vehicles or the like to the bagasse furnaces.

Hot air injected through the perforated tubes 27 into the bagasse gathering tubes is driven by ventilator fan 24 through the auxiliary heaters 32 adjacent the tubes 25, to be passed to the auxiliary perforated tubes 27, thereby allowing the bagasse to be dried more quickly, the evaporation steam being exhausted at the top portion of the gathering tube.

Otherwise, it would be possible to avoid the use of atmospheric air and the heaters 21 therefor. For this purpose, hot gases should be taken at the end of the casing 1 through one or more extractors, after their heat has been utilized to heat bagasse gathering tubes exteriorly, at the velocity and rate necessary to set the required draught, by closing the gate 48 adjacent the chimney 3, thereby rendering the latter not in use.

The latter procedure in which hot gases from the casing 1 are used, is the most recommendable, for such gases have a minimum moisture content and their control is easier.

It is likewise advisable to utilize only the amount of bagasse that is necessary for combustion, the remainder, which is usually a considerable volume, to be stored for use as a fuel where necessary.

The result obtained in the application of the apparatus to moistened bagasse from sugar-cane mills is surprising, because the dry bagasse discharged by the apparatus will have at the most a moisture content of 5% and its calorific value will be far more than that of the bagasse at present being burned at the furnaces of sugar factories, whereupon the yield in water evaporation in the boilers will reach a maximum, by utilizing the heat of the combustion gases which are produced in the present furnaces and which are allowed to freely escape to the atmosphere through the chimney.

The apparatus of this invention may likewise be used 1 to drive off moisture from the froth obtained from sugar juice clarifiers or from the filters.

It is obvious that changes may be made in the construction details of the casing for the bagasse gathering tubes and of the tubes themselves, without thereby altering the essential character of the invention which is such as claimed hereinafter.

What I claim is:

1. An apparatus for driving ofi moisture from sugarcane bagasse at sugar factories having a boiler furnace and a chimney, comprising a heat insulated metallic casing of rectangular shape arranged adjacent the smoke duct leading from the furnace to said chimney, a longitudinal partition in said casing dividing the same interiorly into two compartments, a series of bagasse conducting tubes arranged vertically on both sides of said partition in the path of combustion gases from the boiler furnaces, air heater tubes arranged vertically at one end of said casing and positioned in the path of the combustion gases from said furnaces, conveyor means on said casing for distributing moistened bagasse from the sugar-cane mills to the upper ends of the vertical bagasse conducting tubes, said conveyor means being arranged to convey bagasse discharged from said bagasse tubes to a discharge opening in said casing, blower means for drawing heated air through said second mentioned tubes and injecting the same into the bagasse during its falling movement through said vertical bagasse conducting tubes, and ducts for leading the combustion gases to a conventional chimney after they have yielded their calorific value.

2. An apparatus for driving off moisture from sugarcane bagasse at sugar factories, including a boiler furnace and a chimney, comprising a heat insulated metallic casing of rectangular shape mounted adjacent said chimney for receiving combustion gases from said chimney, a partition in said casing providing a sinuous passageway for said gases, a series of vertical bagasse conducting tubes arranged on both sides of said partition and extending between the top and bottom walls of said casing, the lower portions of said vertical bagasse conducting tubes being shaped to provide open register boxes, the passage of the combustion gases being controlled in two opposite directions around the vertical bagasse conducting tubes by means of said partition, gates arranged in the flow path of said gases for controlling the passage thereof to said pathway, a hot air perforated injection tube mounted in each vertical conducting tube descending along the center thereof and terminating in spaced relation from the lower end of said conducting tube, groups of air heating tubes arranged at one end of the casing and in the path of the combustion gases, blower means for drawing heated air through said last mentioned tubes and forcing it into the injector tubes mounted within the vertical bagasse conducting tubes, an endless conveyor arranged on the casing and movable above and below said bagasse conducting tubes, conveyor flights on said conveyor for distributing moistened bagasse to the upper ends of said bagasse conducting tubes and receiving the treated bagasse as it is discharged from the lower ends of said tubes.

3. An apparatus for driving off moisture from sugarcane bagasse at sugar factories, including a boiler furnace and a chimney, comprising a casing of rectangular shape installed at the passageway for the combustion gases from the boiler furnaces into said chimney, said casing being made of metal and having an inner heat insulating lining, a longitudinally extending partition in said casing for dividing the same, a cross section partition adjacent the passage of combustion gases leading to the chimney, a series of vertical bagasse gathering tubes arranged in groups of three and mounted to extend through the top and bottom walls of the casing, register boxes on the upper and lower ends of said tubes, rotatable gates in said tubes for regulating the rate of fall of the moistened bagasse through said vertical bagasse conducting tubes, motor means for controlling said gates, gearing connecting said motor means to the gates in said tubes, rotatable gates for controlling the passage of combustion gases around said vertical bagasse conducting tubes in two opposite directions, a perforated injector tube mounted in and descending along the center of each bagasse conducting tube with its lower end in spaced relation from the lower end of its respective tubes, a series of air tubes at one end of the casing arranged in the path of the combustion gases, blower fan means for drawing air after it is heated through said air injection tubes, a water heater arranged lengthwise of said casing adjacent the longitudinal partition thereof, an endless conveyor installed around the casing having rake flights for distributing moistened bagasse to the upper register boxes of the vertical bagasse conducting tubes and arranged to receive dried bagasse discharged from the lower register boxes of the bagasse conducting tubes for conveying said dried bagasse to a discharge point, and a heater for feed water for boilers which are installed in the duct for the passage of combustion gases to the spaces in the casing occupied by the groups of vertical bagasse conducting tubes.

References Cited in the file of this patent UNITED STATES PATENTS 322,257 Chase et al July 14, 1885 746,822 Gorham Dec. 15, 1903 1,509,280 Baker et al. Sept. 23, 1924 1,863,803 Pantenburg .Iune 21, 1932 2,480,146 Lee Aug. 30, 1949

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