ZA200809744B

ZA200809744B - Dewatering apparatus for sugar cane

Info

Publication number: ZA200809744B
Application number: ZA200809744A
Authority: ZA
Inventors: Paul Thiel
Original assignee: Paulthiel
Priority date: 2008-04-30
Filing date: 2008-11-17
Publication date: 2009-11-25

Description

. FIELD OF THE INVENTION

This invention relates to a dewatering apparatus for sugar cane bagasse but not restricted to sugar cane bagasse.

BACKGROUND OF THE INVENTION

Diffusion is one of the methods used for the extraction of juice from cane in the process of the production of sugar. As a result of the water being added to the prepared sugar cane, known as Bagasse, the bagasse leaving the Diffuser has a high water content.

This bagasse must now be dried to a lower moisture content.

In the normal practice of drying the bagasse two milling units are used. Unfortunately the milling units are not only an expensive item to purchase but also expensive to maintain and are high consumers of power.

In order to be competitive it is essential for a factory to be efficient in all aspects of producing sugar which means it must be cost effective and energy efficient. It was for this reason that a dewatering device was developed.

In this invention the objective of the dewatering device is to replace one of the mills by reducing the moisture content of the bagasse to an acceptable level so that a single bagasse drying mill is not overwhelmed by the quantity of water and is therefore able to reduce the moisture content of the final bagasse to an acceptable level. A further object of the invention is to significantly reduce the energy requirements of the apparatus relative to prior art arrangements. The third objective is to reduce the annual maintenance costs for the drying of the Diffuser as the maintenance of this invention is greatly reduced when compared to the conventional Diffuser bagasse drying mills. The sum of these improvement is a more cost effective and consequently, competitive installation.

/ . THE INVENTION

According to the invention, the dewatering apparatus comprises a pair of housings supporting three rolls between them, the rolls being secured by bearings mounted in the housings; the rolls being configured in an unequal triangular format with an upper (top) roll, a roll on the side that the bagasse enters (feeder roll) and a roll at the outlet end (discharge roll); a hydraulic cap positioned above the top roller being used to maintain a constant pressure between the top and discharge rolls; an implement located between the feeder roll and the discharge roll to guide the bagasse from the feeder roll to the discharge roll; the top and discharge rolls being fitted with a scraper for removing bagasse from the roll; the rolls having circumferential grooves being generally V-shaped in section, the grooves having a profile with flat sections of greater width, at the crest of the grooves, than the flat sections at the base of the grooves, to facilitate drainage.

In the invention, the top and discharge rolls are vertically aligned directly below the hydraulic cap, up to and including a tolerance of five degrees either side of this vertical alignment as shown in figure 3.

This arrangement of rolls is in contrast with prior art three roller systems in which the feed and discharge rolls are located at an angle to the top roll which increases the force necessary to be able to exert the required load on the feed and discharge rolls.

Having the load directly above and in line with the top and discharge roll results in free floating of the top roll, no unnecessary loss of power to wear and consequently a reduction in power required to drive the invention.

In the preferred form of the invention, the pitch of the grooves on the lower rolls (feeder and discharge rolls) is between 75% and 85% of the depth of the grooves of the lower roll, the pitch of the grooves on the upper roll (top roll) may be equal to or greater than that of the grooves to the lower rolls. It has been established that a pitch of between 108% and 116% of the height of the grooves of the top roll, is most efficient.

. Also in the preferred form of the invention the included angle of the grooves on the lower roll is lower than that of the top roll. The angle is preferably between 27 and 32 degrees.

The grooving configuration described above functions: a) to permit easy drainage of the juice from the rolls, and b) to pressurize the bagasse sufficiently to remove the liquid without blocking the drainage from the rolls.

Many different configurations of grooving have been used in sugar cane mills over many years but as the requirements of the apparatus of the invention are slightly different to these mills the configuration used here are different to those used in the past and present.

The housings further include hydraulic caps which permit the top roll to maintain constant pressure on the bagasse at all times for obtaining optimum juice extraction.

Furthermore the top roll is able to oscillate.

EMBODIMENT OF THE INVENTION

An embodiment of the invention is described below with the accompanying drawings in which:

Figure 1 is a side view of a prior art, three roller system;

Figure 2 is a side view of a typical installation of an apparatus according to the invention;

Figure 3 is a side view of the apparatus showing the top roll and discharge roll;

Figure 4 is a plan view of the invention;

Figure 5 is a sectional view through the grooves of the feeder roll; and

Figure 6 is a sectional view through the top and feeder rolls in mesh. in Figure 1, a prior art three roller system is shown. It is clear that the hydraulic cap A and top roll B are aligned vertically, but that feed roll C and discharge roll D are at angles (in this example 45° and 42° respectively) thereto. Accordingly force exerted by the a oo - hydraulic cap onto rolls C and D is lost to a tangential or radial load exerted on the sides of the top roll bearing and mill housing. This results in excessive wear.

In Figures 2 to 4, an apparatus 10 for dewatering bagasse is shown to comprise a pair of housings 12 supporting a feeder roll 14, a top roll 16 and a discharge roll 18, between them in an unequal triangular configuration, (best viewed in Figure 2) and a hydraulic cap 19 exerting pressure on the top roll 16.

Bagasse enters at 20 and is compressed between the feeder roll 14 and the top roll 16 before being fed by a conveying implement (not shown) to be further compressed between the top roll 16 and discharge roll 18. In Figure 3, the alignment of the top roll 16, discharge roll 18 and hydraulic cap 19, is shown. The force exerted by the hydraulic cap extends linearly through the axis top and discharge rolls resulting in minimal tangential load loss and reduced wear and tear.

The rolls are grooved to enable water compressed from the bagasse to drain from the rollers. In Figure 5 the grooves have crests (22) with flat tops (24) which are wider than the flat bottoms (26) of the troughs of the grooves. This results in the grooves of two engaging rolls being in imperfect register which facilitates the drainage.

In Figure 6, the height (a) of the grooves of the feeder roli 14 are shown to be greater than the depth of the grooves of (b) top roll 16.

Similarly the included angle of the grooves of the lower roll is smaller than that of the grooves of the upper roll.

Claims

: B fi : CLAIMS:

1. The dewatering apparatus comprises a pair of housings supporting three rolls between them, the rolls being secured by bearings mounted in the housings; the rolls being configured in an unequal triangular format with an upper (top) rofi, a roll on the side that the bagasse enters (feeder roll) and a roll at the outlet end (discharge roll); a hydraulic cap positioned above the top roller being used to maintain a constant pressure between the top and discharge rolls; an implement located between the feeder roll and the discharge roll to guide the bagasse from the feeder roll to the discharge roll; the top and discharge rolls being fitted with a scraper for removing bagasse from the roll; the rolls having circumferential grooves being generally V-shaped in section, the grooves having a profile with flat sections of greater width, at the crest of the grooves, than the flat sections at the base of the grooves, to facilitate drainage.

2. The dewatering apparatus according to claim 1 in which the top and discharge rolis are vertically aligned directly below the hydraulic cap, up to and including a tolerance of five degrees either side of this vertical alignment.

3. The dewatering apparatus according to claim 1 in which the pitch of the grooves on the lower rolls (feeder and discharge rolls) is between 75% and 85% of the depth of the grooves of the lower roll.

4, The dewatering apparatus according to any of the above claims in which the pitch of the grooves on the upper roll (top roll) are equal to or greater than that of the grooves to the lower rolls.