US1923143A - Manufacture of sugar - Google Patents

Description

-Aug. 22, 1933. L, E, GQUNER 1,923,143

MAUFACTURE oF SUGAR 2 Sheets-Sheet 2 ATTORNEY Aug- 22, 1933. 1 E. GouNER MANUFAoTURE-OF SUGAR Filed April 18, 1950 ONM mw ma mm/ moved. The general laws governing the settling Patented Aug. 22, 1933 MANUFACTURE oF` SUGAR Leonidas E. Gouner, NewOrleans, La., assignor t-o Petree la Dorr Engineers, Inc., N. Y., a Corporation of Cuba New York,

Application April 1s, 1930. seal No. 445,360

10 Claims.

The present invention relates -to the construction and method of operation of apparatus used in the manufacture of sugar, and particularly in the manufacture of cane sugar. Q

.It is well known in the art that sugar juice expressed from the cane is treated with lime and subsequently heated to a temperature of approximately 212 F. to coagulate the albumin and prepare the suspended and coagulated solids therein for subsequent removal in suitable settling apparatus, such as a clarifier of the gravitational separator type. In such apparatus, the lighter particles rise to the surface of the heated liquid in the separator and are removedas scum therefrom, while lthe heavier-particles slowly settle to the bottom of the apparatus and form a sludge or mud, which is periodically or continuously reof suspended solids in sugar'juice are described by Deerr in his volume on Cane Sugar, pp. 269-270, and in essence comprise the initial formation of five distinct superposed zones varying in character from a top zone of clear liquid to a bottom zone of accumulated solids. After 4a certain time interval, the ve zones merge into three and nally into two zones, an upper clear liquid zone and a lower zone of accumulated solids. The clear juice may then be decanted and the solids or mud removed. The decanted juice is delivered to evaporators, where part of the water present is driven oif and crystallization of the sugar occurs. The presence of impurities in the juice delivered to the evaporators is considered to be highly disadvantageous as it delays crystallization of the sugar. The mud taken from the settling apparatus is delivered to suitable lter presses, wherein a portion of the sugar juice contained in the mud is recovered.-

'I'he general object ol my invention is to provide an improved construction, arrangement, and mode of operation of a gravitational separator., primarily intended for use in the continuous defecation of sugar cane juice. A further object of my invention is the provision 'of improved mechanism for removing the solid impurities in the form of mud and scum from the separator. A further object is vthe provision of improved construction and arrangement of means for regulating thedischarge of the decanted liquid from a plurality of sedimentation and decantation compartments in accordance with the supply of y juice to the separator. A further object is the provision of an improved tray or bale construction. A further object is the provision of means for eliminating or minimizing the gyratory movement and regulating the iiow of liquid in the upper portions of the sedimentation and decantation compartments. A further object is the provision -of a separator inwhich a large portion of the excess steam and gases delivered with the (Cl. 21o-55) heated juice is automatically removed without loweringthe temperature of the liquid to an undesirable extent.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specication. For a better understanding of the invention, however, and the advantages possessed by it reference should be had to the accompanying-drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawings:-

Fig. 1 is a sectional elevation of the improved 'gravitational separator of my invention with certainl parts removed for purposes of clarity;

is a section on the line 2&2 of Fig. l, with a portion of the tray surface broken away;

Fig. 3 is a horizontal section on the line 3 3 of Fig. 1 with a portion of the blade ring broken away;

Fig. 4 is a vertical section on the line 4 .4 of Fig. 1; and

Fig. 5 is a vertical section on the line 5 5 of Fig. 2.

The gravitational separator illustrated comprises a 4tank or shell A having an upwardly tapered top section A', a cylindrical middle section A2, and an inverted conical bottom section A3, Suitable columns A4 and braces A5 support the tank at its'lower end. The outer sides of the tank may well be covered in the usual manner with a layer` of heat insulating material to conserve the heat in the liquid contained therein. The upper end of the top section A contacts with, and is secured to the outer side of a casing B, the latter being constructed with an upper cylindrlcal section B and a lower inverted frustoconical section B2, which depends a substantial distance into the middle section of the tank A. The tank section A preferably contacts with the casing B adjacent to the junction of the casing sections B and B2. frusto-'conical in form, extends from the inner side of the casing section B2 upwardly to the upper level of the section B', as shown in Fig. 1. An annular plate B4 closes the upper end of the downwardly tapering ash chamber a formed by the casing Ba and section B. shaped plate C is positioned within an intermediate portion of the casing B3, with its horizontal section C secured to, and its vertical secspaced from, the inner side of the casing B3 to form a gutter Cil opening to an external discharge pipe C5. B5 is connected to the chamber a above the level of the plate C and through which inlet the juice is continuously delivered from the juice heater' or heaters. ings l?.6

Fig. 2

tion C2 A second casing B3, also An annular angle- A sugar juice inlet pipe A multiplicity of discharge openare arranged in a ring in the casing B3 adjacent to its junction with the casing section B2.

A pressure relief valve D is mounted on the plate B4 and arranged to automatically discharge steam and gases separated in the ash chamber a. The relief valve shown is of the balanced valve type, comprising an inlet pipe D', a valve body D2, a discharge pipe D3, and a valve disc D4 which is mounted on a pivoted valve lever D5. The lever D5 isexternally connected to a weight bar D5 which carries Aadjustable weights D' and D8 for balancing the valve and determining the valve operating pressure, respectively.

The tank interior is provided with a plurality of vertically spaced conical trays or bales E arranged in conjunction with the tank A to form a series of superposed sedimentation and decantation compartments b, c, d, e and f. Each of the trays is constructed by connecting a plurality of segmental transversely curved tray sections E along their contacting side edges E2 as shown in Figs. l and 2. Each tray forms the top wall for the subjacent chamber, the top wall of the chamber b being formed by the tank section A and the bottom wall of the chamber f by the conical tank section A3. Each tray is supported from the tank by suitable connections at the tray upper end and thus closes the upper end of the subjacent chamber. The trays are inclined at an angle substantially corresponding to the slope of the tank section A3, with the upper end of the uppermost trayv connected to the upper end of the tank section A2. The lower ends of the trays are cut away toform central openings E3, the peripheries of which are substantially in vertical alignment with the periphery of the lower discharge end of the casing section B2. It will be noted that the opening in the lowermost tray is substantially greater than in the upper trays, primarily because of the greater size of the compartment f as compared to the superposed compartments c, d and e."

In the settling and decantation operation hereinafter described, the-various compartments are filled with a heated mixture of sugar juice and suspended solids. When the liquid is in a substantially quiescent state, the solids gradually settle and deposit on the corresponding trays, the rate of settling being partly dependent on the quiescence of the liquid. The separated solids or mud accumulate at a relatively rapid rate and in continuously operated settling apparatus of the type described would quickly lower the capacity of the apparatus unless wholly or partly removed. Tray scraping mechanism of a generally well known type but specifically differing in construction, arrangement and effectiveness from that heretofore in use, is employed for this purpose.

Y The tray scraper mechanism preferably consists of a vertically disposed shaft F extending axially through the tray openings E3 and rotatably supported in a step box F' at the bottom of the apparatus and by vertically spaced bearings F2, F3 and F4. The shaft is arranged to be continuously rotated through a worm gear F5 and worm F5, from a suitable source of power at a relatively low rate, such as one revolution every fifteen or twenty minutes. The portion of the shaft F in or adjacent to each compartment is connected to two or more sweep arms H radially arranged relative to the shaft and inclined at an angle corresponding to the slope of the adjacent tray. Each arm is in the form of an angle beam with its lower end 'secured to the shaft F by two-part castings I-I clamped on the shaft and carrying a disc H2 downwardly concaved. Bracket arms H3 aid in supporting the sweep arms from the shaft. The shaft is normally rotated in a clockwise direction as seen in plan and with the vertical plate H4 of each arm at the fore-part thereof. Each horizontal arm plate H5 moving in proximity to the adjacent tray surface is provided with a plurality of radially spaced scraper blades or plows J flexibly connected to the arm, as shown in Figs. l and 2.

The blades J are substantially rectangular in form and curved longitudinally and inwardly, as shown in Figs. 2 and 5 and arranged with each lower scraping edge J in contact'with a substantial portion of the upper surface of the corresponding tray. The lend of each scraper adjacent the supporting sweep arm contacts with the lower side of a hinge plate J2 hinged at J5 to the arm plate H5. The scraper end is positioned between ears J4 depending from the free end of the hinge plate. Pins J5 extending through the ears J4 and Scrapers J provide a pivotal connection for the scraper to the plate.

In scraper constructions heretofore in large diameter clarifiers it has been the practice to position the scrapers so that they do not contact with the 'tray surface but work free and above the trays. This has been necessitated because of the unevenness of the tray surface and jamming and breaking of the Scrapers and sweep arms that would otherwise occur. In such an arrangement, a substantial quantity of mud will always remain onthe trays. This bottom mud contains only a small amount of sugar liquids and is of a character tending to effect inversion or hydrolysis of the sugar liquids and therefore its removal is highly advantageous. The arrangement and curvature of the scrapers cause this deposited mud to be constantly moved toward the central discharge openings E3 in the trays, and through which it drops to the bottom of the clarifier.

The bottom of the clarifier terminates in a small cone G having a sharper inclination than the tank section A3 and to which cone a mud discharge pipe G is connected. A central tank supporting member G2 surrounds the cone G. The discharge pipe G' extends upwards alongside the tank and at a point above the normal liquid level in the clarifier is connected to a pump (not shown)l which discharges the mud to the filter presses. l

The sugar juice passes from the heaters through the inlet B5 into the flash chamber a, which being closed, causes the mass of juice to flow downwardly and out through the casing openings B5. The mass of liquid issuing from the openings B5 into the reaction chamber g, has a general path Yof flow downward. The normal liquid level in the reaction chamber g is maintained between the lines X-X and Z--Z by regulable liquid discharge means hereinafter described. AS long as the liquid in the reaction chamber remains above a certain temperature. the light impurities, such as fats and waxes, will rise to the surface in the form of scum and will be skimmed off the surface into the scum gutter C4 by a series of scum ploughs K. The ploughs K have an inclined lower edge K which contacts with the upper edge of the plate C, and are loosely attached to and supported from a ring plate K2. The plato K2 is mounted on spider arms K3 which are secured to and rotate with the operating shaft F. The scum passing over the edge of the plate C into the gutter is discharged through the scum discharge pipe C to suitable lter presses.

The liquid flows down through the lower portion of the reaction chamber g into the various sedimentation and decantation compartments, where the settling and separation of the heavy impurities occur. The conical form of these chambers tends to create a gyratory iiow of the liquid therein with consequent delay in the rate of settling. Vertical bailles in the form of T-bars M are provided to eliminate or minimize the gyratory ow. The bars M are arranged at the underside of the contacting edges of the tray sections E2 and the tray sections are secured together and the bales supported in the desired position by 'securing the base flanges M of the T-bars to the adjoining edges of the tray sections. The baiiles extend downwardly into the upper settling or clear liquid zone of the compartments and preferably extend substantially the full length of the tray sections. The baffles guide the ow of clear liquid radially outward towards the sides of the tank. Any particles of impurities carried along between the baiiles will drop out before the sides of the tank are reached.

An annular clear liquid discharge manifold is provided for each settling compartment by narrow annular plates N secured to the inner side of the tank and extending between the tank side and the underside of the trayswhereby a manifold triangular in vertical cross-section is formed at the upper end of each compartment. Clear liquid ow from each compartment into the corresponding manifold is permitted by openings N' in the plate N between each pair of baffles M.

One or more clear liquid discharge pipes P separately connect each compartment manifold to separate control boxes R in a reservoir R arranged as shown in Figs. 1 and 4. The control boxes are illustrated as rectangular in horizontal and vertical cross-section and separated from one another and from a common discharge box R2 by vertical partitions R3 and R4, respectively. One or more discharge pipes R5 connect the box R2 with the evaporators. The discharge of liquid from the various control boxes R to the discharge box R2 is regulated and controlled as hereinafter described by Weir valves S arranged in the partition R4. The portion of the partition R4 in front of each box R is cut awayfto form upper and lower fan shaped weir openings S and S2, respectively, arranged with their tapered ends adjacent but slightly spaced vertically. The weir openings, as shown in Fig. 1, extend above and below the desired normal liquid level in the reaction chamber. Between the ends of the openings, the partition is provided with a bearing for a horizontal valve operating shaft T on which a fan-shaped valve T' is mounted at the inner side of the partition R4. The valve T is of sufficient size to cover either Weir opening. A valve, operating lever T2 is secured to the shaft T externally of the corresponding control box and arranged for moving the valve relative to the Weir openings.

With the apparatus constructed and arranged as described, the preferred method of operation comprises the introduction of the sugar juice from the heaters at a temperature sufficient to effect the rise of the lighter impurities in the liquid in the reaction chamber and the consequent formation of a thick scum on the surface of the liquid. As the liquid enters the flash chamber a, a substantial portion of the excess steam 3 and gases is separated from the liquid by a flashing action due to the lower pressure in the chamber. Any desired pressure can be maintained in the flash chamber due to the construction and operation of the relief valve D. The liquid then flows downwardly through the flash chamber and reaction chamber. In the latter, the liquid level is normally between the lines X-X and Z-Z and the scum is constantly swept off by the ploughs Ki into the gutter C4 from which it is delivered to the lter presses. The top of the reaction chamber being open to the atmosphere, gases in the liquid may freely escape therefrom. The liquid delivered to the various compartments passes through the process of sedimentation and decantation heretofore described. The mud constantly deposited on the tray surfaces is worked towards the corresponding central tray opening, and nally reaches the bottom cone G and discharge pipe G. The tray Scrapers are constructed and arranged to sweep over the entire tray surface at a rate suilicient to effect the removal of the vmud eiiciently but without agitating the liquid sufficiently to lengthen the rate of settling.

The liquid passes out of the sedimentation and decantation compartments b f through the separate pipes P leading to the corresponding control boxes R. The supply of sugar juice to the apparatus from the heater is highly variable because of the wide differences inamount and character of the cane operated on by the mills and consequent variations in the amount of juice expressed. In consequence, the liquid level in the reaction chamber g would often rise sufciently to cause clear juice to overflow into the scum gutter C4 with a corresponding loss, or increase in the cost of operation to recover the juice in the scum filter presses. By the present invention, the liquid level in the reaction chamber is maintained at a level suiiicient to permit the removal of the scum thereon by the ploughs K, and any undesirable increase in liquid level is prevented by an effective regulation of the discharge of clear liquid from the individual control boxes. The control boxes and weir openings are so arranged that when the liquid in the reaction chamber is at its normal level, the lower weir openings will be closed by the valves T and will be maintained closed until the clear liquid begins to run over the upper weir into the discharge chamber. Because of the Weir construction, any overcharge of liquid to the reaction chamber will be distributed equally to all the control boxes, and thereby prevent disturbances of the liquid in the various compartments and an undesirable increase in liquid level in the reaction chamber. The present control arrangement eliminates the necessary continuous regulation of the effective levels of the discharge pipes by sliding sleeves heretofore in use. Individual regulation of the control valves is made when the operator notes a cloudy condition of the liquid in the corresponding control box. Such a condition indicates that the rate of flow through the corresponding compartment is greater than the rate of settling therein. The effective hydrostatic head on the liquid therein is therefore decreased by further closing the lower weir opening of the control valve until this condition no longer exists.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:-

1. Gravitational separator apparatus comprising a plurality of conical trays arranged to form a series of superposed sedimentation and decantation compartments, a liquid outlet pipe connected with each of said compartments near the top thereof for permitting a flow of liquid therefrom, a central discharge opening in each of said trays, a vertically disposed shaft passing through said discharge openings, sweep arms mounted on said shaft and extending substantially parallel to the upper surface of each of said trays, a plurality of rearwardly curved scrapers at the'rear of each of said sweep arms and arranged to contact with the upper surface of the corresponding adjacent tray, and a hinged connection between the forward portion only of each of said Scrapers and the adjacent sweep arm.

2. Gravitational separator apparatus comprising a plurality of conical trays arranged to form a series of superposed sedimentation and decantation compartments, a liquid outlet pipe connected with each of said compartments near the top thereof for permitting a flow of liquid therefrom, a central discharge opening in each of said trays, a vertically disposed shaft passing through said discharge openings, sweep arms mounted on said shaft and extending substantially parallel to the upper surfaces of each of said trays, a plurality of hinged plates connected to radially spaced points on each of said sweep arms, and a hinged scraper pivotally mounted on each of said hinge plates and arranged with a lower curved contact edge in contact with the upper surface of the corresponding adjacent tray.

3. Gravitational separator apparatus comprising a plurality of vertically spaced conical trays arranged to form a series of superposed sedimentation and decantation compartments, each of said trays being formed by a plurality of transversely curved imperforate plate sections with their side edges in contact, a radially extending baie at the underside of each pair of contacting plate edge portions adapted to substantially minimize gyratory flow in the sub-jacent compartment, and means securing said plate sections and bafe together.

4. Gravitational separator apparatus comprising a plurality of vertically spaced conical trays arranged to forma series of superposed sedimentation and decantation compartments, each of said trays being formed by a plurality of transversely curved imperforate plate sections with their side edges in contact, a radially extending T-bar at the underside of each pair of contacting plate edge portions, and means for securing said sections and T-bar together with the vertical section of said T-bar depending in the subjacent compartment and being adapted to substantially minimize gyratory iiow therein.

5. Gravitational separator apparatus comprising a tank, a plurality of vertically spaced conical trays arranged in said tank to form a series of superposed sedimentation and decantation compartments, a liquid outlet pipe connected with each of said compartments adjacent to the junction of the Lipper' tray wall of said compartment and said tank, an annular plate connecting said upper tray wall and tank immediately below the corresponding liquid outlet pipe, and openings formed in said plate member for the passage of liquid from said compartment to said liquid outlet pipe.

6. Gravitational separator apparatus comprising a tank, a plurality of vertically spaced conical trays arranged in said tank to form a series of superposed sedimentation and decantation compartments, a liquid outlet pipe connected with each of said compartments adjacent to the junction of the upper tray wall of said compartment and said tank, an annular plate connecting said upper tray wall and tank immediately below the corresponding liquid outlet pipe, vertical baffles depending from the undersides of said tray surfaces and extending radially thereon towards the sides of said tank, and openings formed in said plate member between each pair of vertical baffles for the passage of liquid from said compartment to said liquid outlet pipe.

7. Gravitational separator apparatus comprising a series of superposed sedimentation and decantation compartments, a liquid outlet pipe connected with each of said compartments near the top thereof for permitting a flow of liquid therefrom, a plurality of separate discharge control boxes separately connected to said pipes, a weir discharge opening from each of said boxes, and valve means for regulating the effective area of each of said weir openings in accordance with variations in the supply of liquid to said apparatus.

8. Gravitational separator apparatus comprising a series of superposed sedimentation and decantation compartments and an upper reaction chamber, a scum overflow gutter in said chamber, a liquid outlet pipe connected with each of said compartments near the top thereof for permitting a flow .of liquid therefrom, a plurality of separate discharge control boxes separately connected to said pipes and at the level of said chamber, a weir discharge opening from each of said boxes, and valve means for regulating the effective area of each of said weir openings in accordance with variations in the liquid level in said chamber relative to said scum gutter.

9. Gravitational separator apparatus comprising a series of superposed sedimentation and decantation compartments, a liquid outlet pipe connected with each of said 'compartments near the top thereof for permitting a flow of liquid therefrom, a plurality of separate discharge control boxes separately connected to said pipes, an upper normally open weir opening and a lower normally closed Weir opening in each of said boxes,4 and Valve means normally closing said lower weir opening and operable to regulate the effective area thereof in accordance with variations in the supply of liquid to said apparatus.

l0. Gravitational separator apparatus comprising a series of superposed sedimentation and decantation compartments, a liquid outlet pipe connected with each of said compartments near the top thereof for permittingI a fiow of liquid therefrom, a reaction chamber arranged above said compartment, a closed flash chamber surrounding said reaction chamber, and a pressure relief valve connected to said flash chamber for automatically removing gases dashing from said liquid in said chamber.

LEONIDAS E. GOUNER.

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