Patent Application
20120329630
The processing of sugar to produce refined sugar can include several steps, for example, an evaporation step followed by a crystallization process. During an evaporation step, sugar liquor may be concentrated to sugar syrup. Sugar crystals may also evaporate out of solution. The sugar syrup may then be sent to crystallizers for further processing to produce sugar crystals. The resulting mixture from the crystallization step is called massecuite, which may be composed of sugar crystals in a thick, viscous liquid (molasses). The massecuite may also contain dissolved sugar and organic and inorganic impurities. To isolate the sugar crystals, the massecuite may be processed through a continuous centrifuge to separate the sugar crystals from the liquid molasses.
Two ways of introducing a feed to a continuous centrifuge are believed to exist—a side feed arrangement where massecuite is fed to the bottom of a rotating conical basket down the outside of a fixed metal probe and a center feed arrangement where the feed is fed to the center of the rotating conical basket. Particularly, in a massecuite feed, it may be important to introduce the feed in such a way so as to avoid any damage to the sugar crystals. It may also be important to introduce the massecuite feed in such a way to achieve proper separation of the sugar crystals from the molasses.
Accordingly, there is a continual need for improved centrifuge systems, and components therewith, which deliver massecuite to a centrifuge to achieve improved separation with minimal damage of the sugar crystals from the molasses. It is believed that no one prior to the inventor has made or used an invention as described herein.
The system described herein is a screen clamp with integrated center feed that is designed to direct massecuite into a centrifuge basket for separation. The screen clamp with integrated center feed is also configured to secure the basket filtering screens within the centrifuge basket.
In one example, a screen clamp with integrated center feed is provided. The screen clamp comprises: a) a feed cone having a base and sidewall, wherein a center of the base has a feed opening and the sidewall has one or more discharge openings; and b) an outer flange attached to and extending along a bottom edge of the feed cone, wherein the outer flange is configured to secure a basket filtering screen to a centrifuge basket. The screen clamp may be configured to direct a massecuite feed entering the feed opening through the one or more discharge openings and onto the basket filtering screen. The screen clamp may further comprise a weir.
In another example, a continuous centrifuge comprising a centrifuge housing and a center feed arrangement disposed in the centrifuge housing is disclosed. The center feed arrangement comprises: a basket hub, a basket rotatable around a vertical axis and attached to the basket hub, a basket filtering screen attached to the basket, a screen clamp that fastens the basket filtering screen to the basket, the screen clamp comprising: a feed cone having a base and at least one sidewall extending downwardly from the base, wherein a center of the base comprises at least one feed opening and the bottom of the sidewall comprise one or more discharge openings, and an outer flange attached to and extending along a bottom edge of the feed cone, and a center feed pipe positioned to feed massecuite to the center of rotation of the conical screening basket. The center feed arrangement may be configured to direct a massecuite feed through the feed opening of the screen clamp and through the one or more discharge openings of the screen clamp to the conical screening basket.
Features and benefits of the various embodiments of the present invention will become apparent from the following description, which includes figures and examples of specific embodiments intended to give a broad representation of the invention. Various modifications will be apparent to those skilled in the art from this description and from practice of the invention. The scope is not intended to be limited to the particular forms disclosed and the invention covers all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the claims.
While the specification concludes with claims which particularly point out and distinctly claim the invention, it is believed the present invention will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings. In the drawings, like numerals represent like elements throughout the several views.
The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.
Referring to
The feed cone 105 comprises a base 120, which is the uppermost portion of the feed cone 105, and further comprises one or more sidewalls 125 extending downwardly from the base 120. The sidewall 125 may be angled outwardly from the base 120, such that the lower end of the feed cone 105 has a greater diameter than the upper end of the feed cone 105 i.e., the base 120. The lower end of the feed cone 105 is fully open or substantially open in order to be attached over a basket hub 300 as described below. In some examples, the sidewall 125 is angled outwardly from vertical between about 2 degrees and about 12 degrees. In other examples, the sidewall 125 is angled outwardly from vertical between about 4 degrees and about 11 degrees. In further examples, the sidewall 125 is angled outwardly from vertical between about 8 degrees and about 11 degrees. As depicted, the feed cone 105 is frusto-conical in shape. However, the feed cone 105 can take on other suitable shapes and configurations that may be apparent to one skilled in the art in view of the teachings herein. For example, the feed cone 105 may be cylindrical or frusto-pyramidal in shape. Where the feed cone 105 is cylindrical in shape, the sidewall 125 is not angled outwardly from the base 120, and the lower end of the feed cone 105 may have a diameter that is the same as the upper end of the feed cone 105.
The center of base 120 has a feed opening 130. The feed opening 130 is sized to permit massecuite to flow through the opening. The feed opening 130 may also be configured to allow for a massecuite center feed pipe to fit within the feed opening. In some examples, the feed opening 130 may be sized to be from about 3″ to about 8″. In other examples, the feed opening 130 may be sized to be from about 4″ to about 6″. The base 120 is depicted in
The outer flange 115 is positioned at the lower end of the feed cone 105 and extends upwardly. The outer flange 115 is attached to and extending along a bottom edge 155 of the feed cone 105. The outer flange 115 has an inner side 135 and an exterior side 140. A channel 145 is formed between the inner side 135 of outer flange 115 and the exterior side of sidewall 125 of feed cone 105.
As depicted in
The base 120 may also comprise one or more fastener openings 150 in the base. Without being bound by theory, it is believed that locating the one or more fastener openings 150 in base 120 can make the fasteners used within the one or more fastener openings 150 more accessible as compared to other types of screen clamps. Specifically, some screen clamps use fasteners located in the channel 145 area, which can make the fasteners erode quicker due to contact with the massecuite, make the fasteners less accessible, and make the fasteners harder to remove after contact with the massecuite (a sticky, viscous substance). In some examples, between 4 to 12 fasteners may be used within the one or more fastener openings 150; however, various amounts of fasteners are contemplated.
As depicted in
The sidewall 125 also comprises one or more discharge openings 110 configured to allow massecuite flow therethrough. The one or more discharge openings 110 are formed along a bottom edge 155 of the feed cone 105. As depicted in
Depicted in
The screen clamp 545 fits inside the bottom of the conical basket 530 and is attached to basket hub 525. When the screen clamp 545 is in place and secure, it pinches the bottom of the top screens 540 and backing screen 535 (to hole them in place) between the screen clamp 545 and basket 530. Thus, the basket hub 525 and screen clamp 545 secure the basket 530 and basket filtering screens 535, 540 together between the basket hub 525 and screen clamp 545. The screen clamp 545 may rotate within the centrifuge along with the basket assembly 500.
As noted above, massecuite is fed into the center of the screen clamp 545. The massecuite then flows to the bottom of screen clamp 545, through the one or more discharge openings 110, and up and over the outer edge of the outer flange 115. The massecuite then flows onto the basket filtering screens 535, 540. The screens 535, 540 have openings that are sized large enough to allow molasses to pass through, sized small enough to prevent a majority of the sugar crystals from passing through. In some examples, the screen openings are sized so as to prevent at least 60% of the sugar crystals from passing through. In some examples, the screen openings are sized so as to prevent at least 75% of the sugar crystals from passing through. In some examples, the screen openings are sized so as to prevent at least 85% of the sugar crystals from passing through. The top screen 540 may be made from thin (e.g., from about 0.3 mm to about 1.0 mm) chrome plated nickel or laser cut stainless steel. The top screen 540 may be made up of between two and five overlapping segments that are arranged evenly around the inside of the basket 530. As the basket assembly 500 rotates, the high gravitational force causes the sugar crystals to migrate up the top screen 540, while the molasses drains out through the openings in the basket filtering screens 535, 540 and basket 530.
Referring to
Also depicted in
The sugar discharge passageway 610 is the passage created between the labyrinth 625 and the housing 620 of centrifuge 605. The separated sugar crystals fall through sugar discharge passageway 610 and exit out of sugar discharge outlet 630. There may be one or more sugar discharge outlets associated with centrifuge 605. The molasses discharge outlet 615 may be disposed at a lower end of the basket assembly 500. The molasses separated from the sugar crystals may be discharged through the molasses discharge outlet 615. There may be one or more molasses discharge outlets associated with centrifuge 605.
In operation, as shown in
The massecuite feed may be delivered into basket assembly 500 from a storage or supply tank (not pictured) or may come directly from a prior sugar processing step, e.g., crystallization. The feed flows into the basket assembly 500 through the massecuite center feed pipe 400 to a feed opening 130 in the screen clamp 100.
The vertical centrifuge massecuite feed pipe 400 can deliver a homogeneous massecuite feed, which by gravity and centrifugal force, forces the massecuite down and out evenly through to the bottom of the basket assembly 500 as it rotates. The massecuite center feed pipe 400 may also have a feed water pipe 635 configured to deliver low viscosity fluids, e.g., feed water, surfactants, partially diluted molasses or a combination thereof to the massecuite center feed pipe 400 for mixing with the massecuite feed. As used herein “low viscosity fluids” means fluids with a viscosity that is at least less than the viscosity of the massecuite feed. The addition of these low viscosity fluids can reduce the massecuite viscosity. Specifically, the addition of surfactants can reduce the surface tension of the massecuite and facilitate the separation of sugar crystals from the liquid molasses, i.e., purging. The total amount of low viscosity fluids added may range from about 0% to about 8% by weight of massecuite. In another example, the total amount of low viscosity fluids added may also range from about 0% to about 6% by weight of massecuite.
The massecuite center feed pipe 400 may further comprise a steam jacket 640. Steam may enter the steam jacket 640 through a steam inlet, which optionally is regulated through a control valve. The steam jacket 640 may work to increase the temperature of the massecuite fluid entering the centrifuge 605. Increasing the temperature of massecuite can reduce the massecuite viscosity, thereby improving the massecuite flow and separation of the sugar crystals. The temperature of the massecuite fluid may be measured using a temperature sensor and controlled by an automatic temperature controller, which throttles the control valve to admit the required amount of steam for providing and maintaining a desired temperature. Of course, the massecuite fluid temperature may be increased and/or maintained by other methods. For example, massecuite fluid temperature may be increased and/or maintained by indirect methods, such as, contact with a stationary or rotating heated surface.
While several devices and components thereof have been discussed in detail above, it should be understood that the components, features, configurations, and methods of using the devices discussed are not limited to the contexts provided above. In particular, components, features, configurations, and methods of use described in the context of one of the devices may be incorporated into any of the other devices. Furthermore, not limited to the further description provided below, additional and alternative suitable components, features, configurations, and methods of using the devices, as well as various ways in which the teachings herein may be combined and interchanged, will be apparent to those of ordinary skill in the art in view of the teachings herein.
Versions of the devices described above may be actuated mechanically or electromechanically (e.g., using one or more electrical motors, solenoids, etc.). However, other actuation modes may be suitable as well including but not limited to pneumatic and/or hydraulic actuation, etc. Various suitable ways in which such alternative forms of actuation may be provided in a device as described above will be apparent to those of ordinary skill in the art in view of the teachings herein.
Versions of the devices described above may have various types of construction. By way of example only, any of the devices described herein, or components thereof, may be constructed from suitable metals, ceramics, plastics, or combinations thereof. Various suitable ways in which these and other modifications to the construction of devices described herein may be carried out will be apparent to those of ordinary skill in the art in view of the teachings herein.
Having shown and described various versions in the present disclosure, further adaptations of the devices and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Several of such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For instance, the examples, versions, geometries, materials, dimensions, ratios, steps, and the like discussed above are illustrative and are not required. Accordingly, the scope of the present invention should be considered in terms of the following claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.
