FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Fluidized bed sugar drier


INVENTOR
Arora Premkumar Kartarsingh, Kilburn Engineering Limited, Bhandup West, Mumbai
400 078, Maharashtra, India, an Indian National
APPLICANTS
Kilburn Engineering Limited, Bhandup West, Mumbai 400 078, Maharashtra, India, an Indian Company
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:


FIELD OF THE INVENTION
This invention relates to a fluidized bed sugar drier.
BACKGROUND OF THE INVENTION
Sugar is made mostly from sugarcane, especially in sugar cane growing countries like India. The sugarcane juice is extracted by crushing the cane in a crusher followed by concentrating the juice in concentrators by evaporation and clarifying the juice in clarifiers by sulphonation. The concentrated and clarified juice is crystallized in pan type crystallizers using steam. The crystallized sugar solution is passed through a vertical centrifuge to separate sugar crystals from the mother liquor. The mother liquor is recycled to the concentrators and the sugar crystals are dried, cooled and graded before being packed in bags for storage and transportation. Sugar crystals at about 70°C from the centrifuge are generally dried in a vibratory hopper drier essentially comprising a vibratory slat conveyor. The slats of the conveyor are supported on wooden springs and the movement of the conveyor resembles a walking 'grass hopper' and hence the drier is referred to as vibratory hopper drier in the sugar industry. Layers of sugar crystals travelling on and between pairs of upper and lower slats are dried by blowing hot air through the gaps between pairs of upper and lower slats. As the layers of sugar crystals are not evenly spread on and between pairs of upper and lower slats, the intensity of heat reduces across the layers of sugar crystals falling down from an upper slat to a lower slat and there is a large temperature gradient across the layers of sugar crystals. As a result, the sugar crystals are not uniformly dried. Non-uniform drying gives rise to lump formation and reduces the shelf life of sugar. Due to the large temperature gradient, thermal energy consumption of a vibratory hopper drier is increased, so also wastage of thermal energy by the drier. Because of the sliding movement of the sugar crystals on the
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slats, dust generation is very high. Hardly a small percentage of the sugar dust falling on the floor is swept and recovered and put into the concentrators. There is thus large amount of wastage of sugar as dust which flies around and collects on the sugar crystals. As the sugar crystals are not dried uniformly and are covered with sugar dust, they are not a very white and look dull. A slat conveyor usually extends right upto the bagging section and includes a large cooling section as the sugar crystals require increased cooling duration due to the non-uniform drying thereof Large cooling section increases the space requirement for occupation of the conveyor and also cost of the conveyor. The slats supporting springs require periodic replacement thereby increasing the maintenance cost of the drier.
OBJECTS OF THE INVENTION
An object of the invention is to provide a fluidized bed sugar drier which dries the sugar crystals uniformly and prevents dust generation and lump formation so as to reduce energy requirement for drying and impart luster and whiteness to the sugar crystals and to increase the shelf life of the sugar crystals.
Another object of the invention is to provide a fluidized bed sugar drier which prevents wastage of sugar and which recovers sugar almost completely.
Another object of the invention is to provide a fluidized bed sugar drier which is compact and cost effective.
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Another object of the invention is to provide a fluidized bed sugar drier which is easy to clean and maintain and which is hygienic and has long life.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a fluidized bed sugar drier comprising a drying chamber including sugar feed means at the inlet end thereof and sugar discharge means at the discharge end thereof, a vibratory plenum chamber comprising a channel member extending along the length of the drying chamber, the channel member being supported on a hollow support structure adapted to describe a sinusoidal movement in the forward direction, the hollow support structure being partitioned into a plurality of air compartments along the length thereof, the channel member comprising a plurality of openings along the length of the base thereof, the openings being formed with overhanging projections in the forward direction of the vibratory plenum chamber, the vibratory plenum chamber further comprising drive means connected to the support structure to impart sinusoidal movement to the plenum chamber, a plurality of air blowers disposed along the length of the vibratory plenum chamber in spaced apart relationship, each air blower being connected to each of the air compartments, the drying chamber having atleast one hood at the top thereof, atleast one cyclone separator connected to the hood and a water scrubber connected to the air outlet of the cyclone separator.
The following is a detailed description of the invention with reference to the accompanying schematic drawings, in which;
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Fig 1 is an elevation of the fluidized bed sugar drier according to an embodiment of the invention without the cyclone separators and the water scrubber;
Fig 2 is a plan view of the fluidized bed sugar drier of Fig 1 including the cyclone separators and water scrubber;
Fig 3 is an isometric view of the sugar drier of Fig 1:
Fig 4 is an isometric view of the plenum chamber of the sugar drier of Fig 1;
Fig 5 is a partial crosssectional view of the base of the channel member of the plenum chamber of Fig 4;
Fig 6 is an elevation of the cyclone separators of the sugar drier of Fig 2;
Fig 7 is an elevation of the water scrubber of the sugar drier of Fig 2;
Figs 8, 9 and 10 are elevation, plan and side view of the drive means of the sugar drier of Fig 1; and
Fig 11 is a crossectional view of the driven shaft of the drive means of Figs 8, 9 and 10.
The fluidized bed sugar drier 1 as illustrated in Figs 1 to 11 of the accompanying drawings comprises a drying chamber 2 (Figs 1, 2, 3 and 4). 3 is a feed hopper provided at the inlet end of the drying chamber. 4 is a sugar outlet provided at the discharge end of
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the drying chamber. A vibratory plenum chamber comprising a channel member 5 extends along the length of the drying chamber. The base of the channel member is marked 5a and sidewalls of the channel member are marked 5b and 5c. The channel member is preferably made of stainless steel and is supported on springs preferably stainless steel springs 6 which are mounted on a hollow support structure 7 partitioned into a plurality of air compartments 8a, 8b and 8c by partition walls 8d and 8e along the length thereof. The base of the channel member is formed with a plurality of openings 9 along the length thereof (Figs 4 and 5). The openings are formed with overhanging projections 10 in the forward direction of the plenum chamber. A plurality of air blowers 11,12 and 13 are disposed along the length of the vibratory plenum chamber in spaced apart relationship and connected to air chambers 8a, 8b and 8c via openings Sf, 8g and 8h in the support structure respectively. Air blower 11 is a hot air blower. The heater and motor of the air blower 11 are marked 14 and 15 respectively. Air blowers 12 and 13 are cold air blowers. Air inlet and motor of the blower 12 are marked 17 and 18 respectively. Air inlet and motor of blower 13 are marked 19 and 20 respectively. The drying chamber is provided with three hoods 21, 22 and 23 at the top thereof. The hoods are connected to a common duct 24 which in turn is connected to two cyclone separators 25 and 26 via duct 27. Rotary outlet valves of the cyclone separators are marked 28 and 29 respectively (Fig 6). 30 is a water scrubber connected to the air outlet duct 31 of the cyclone separators (Figs 2 and 7). Water inlet and air inlet of the water scrubber are marked 32 and 33 respectively. Sugar solution outlet of the water scrubber is marked 34. Air outlet of the water scrubber is marked 33a and is provided with an air blower 35. 36 is the motor of the blower 35. 37 is the water pump of the scrubber 30. 38 is a drive means comprising an electric motor 39 having a driven pulley 40 mounted on the shaft 39a thereof (Figs 8, 9, 10 and 11). 41 is a driven shaft rotatably mounted on a pair of
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spaced apart upright members 42 and 43. 44 is a driven pulley mounted on the driven shaft 41 at one end thereof corresponding to the driver pulley on the motor shaft. The driver and driven pulleys are interconnected by belt 45. The driven shaft is formed with a cam profile marked 46. 47 is a first bearing mounted over the cam profile of the driven shaft. 48 is a cross pin mounted across a bracket 49 which in turn is mounted across the support structure. 50 is a second bearing mounted on the crosspin and coupled to the first bearing through a coupler 51. 52 is an access window for cleaning the support structure and channel member base from inside.
During operation of the sugar drier, the motor shaft 39a rotates and transmits the drive to the driven shaft 41 via the driver and driven pulleys 40 and 44 and belt 47 and causes the driven shaft to rotate in the clockwise direction. During rotation of the driven shaft, the bearing 47 transcribes a smooth and gentle up and down rotational movement over the cam profile 46 resembling motion along a smooth curvature or a sine wave in the forward direction. As a result, the plenum chamber 5 describes a sinusoidal movement in the forward direction. Wet sugar crystals (not shown) at about 70° from the centrifuge (not shown) are fed onto the plenum chamber through the feed hopper 3. The sugar crystals spread on the base of the plenum chamber and form a bed and move in the forward direction. Air (not shown) being blown through the openings 9 at the base 5a of the plenum chamber 5 lift up the sugar crystals slightly and also turn or swing them around. The air bubbles through the sugar crystals and comes into contact with all the sugar crystals and all around the sugar crystals. The air also gives a forward momentum to the sugar crystals. As a result of all this, the sugar crystals move forward on the plenum chamber like a fluidized bed. There is intense heat and mass transfer and heat and moisture is removed from the sugar crystals very effectively and the sugar crystals are
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dried uniformly and very fast during their forward movement along the plenum chamber. The dried sugar crystals are discharged through the sugar outlet 4. The exhaust air containing sugar particles is led into the cyclone separators 25 and 26 via the ducts 24 and 27. The sugar particles are separated in the cyclone separators and are collected via the rotary valves 28 and 29. The air in the cyclone separators is led into the water scrubber 30 via the duct 31. This air will contain minute particles of sugar crystals which were not separated in the cyclone separators. This air is wetted with water drops in the water scrubber. The sugar crystals in the air dissolves in the water and the sugar solution is recycled into the crystallizer (not shown) via the outlet 34 of the scrubber. Air practically free from sugar particles is let out through the water scrubber air outlet 33a with the help of the blower 35. The sugar is thus completely recovered and wastage is practically eliminated. Temperature gradient between the sugar crystals and exhaust air is considerably reduced because of the intense heat and mass transfer. Therefore, thermal energy requirement for drying of the sugar crystals is correspondingly reduced. Due to fluidization of sugar crystals, sliding of the sugar crystals on the base of the channel member is avoided and fine generation is reduced. Because of the uniform drying and elimination of dust generation, the sugar crystals will have excellent whiteness and luster. Besides lump formation is reduced and storage life of the sugar is increased. Since the plenum chamber and supporting springs are made of stainless steel, the drier is very hygienic and its maintenance cost is reduced. It is also easy to clean and keep the drier clean. Besides eliminating wastage of sugar, the life of the drier is also increased. Due to uniform and fast drying of the sugar crystals, the drier does not require a long cooling section. As a result, the drier is compact and requires reduced space for occupation. Cost of the drier is also reduced.
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The plenum chamber and the supporting springs need not be made of stainless steel. They can also be made of other mechanically strong and clean and hygienic materials. The hot air blower is optional and is required only when the drier has to operate under cold conditions and the sugar crystals are to be initially heated up to remove moisture partially. The cold air should be otherwise good enough to remove the heat of the sugar crystals and the moisture and ensure uniform drying of the sugar crystals. It is understood that the rate and volume of the air being blown through the openings at the base of the plenum chamber should be effectively controlled to ensure uniform drying of the sugar crystals and also to slightly lift up and turn around the sugar crystals and to give forward movement to the sugar crystals. The number of air blowers and cyclone separators can vary. There can be more than one water scrubber. The side walls of the plenum chamber will prevent the fluidized bed of sugar from dropping down from the sides. The overhanging projections 10 of the openings 9 at the base 5a of the plenum chamber 5 will prevent the sugar crystals from falling down through the openings. They will also provide smooth slide over surfaces for the sugar crystals. The drive means for the plenum chamber can be of a different configuration or construction. The cam follower need not be a bearing. The cam follower comprising a bearing will ensure smooth and friction free rotation and reduce wear and tear to the cam profile. The second bearing is optional but because of the second bearing the load on the crosspin is effectively borne by the second bearing and damage to the crosspin is minimized. It also gives certain amount of flexibility to the crosspin. As a result, the life of the cross pin is increased. The cyclone separator and water scrubber construction can vary. The construction and configuration of the plenum chamber also can vary. Such variations of the invention are obvious to those skilled in the art and are to be construed and understood to be within the scope of the invention.
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We claim:
1. A fluidized bed sugar drier comprising a drying chamber including sugar feed means at the inlet end thereof and sugar discharge means at the discharge end thereof, a vibratory plenum chamber comprising a channel member extending along the length of the drying chamber, the channel member being supported on a hollow support structure adapted to describe a sinusoidal movement in the forward direction, the hollow support structure being partitioned into a plurality of air compartments along the length thereof, the channel member comprising a plurality of openings along the length of the base thereof, the openings being formed with overhanging projections in the forward direction of the vibratory plenum chamber, the vibratory plenum chamber further comprising drive means connected to the support structure to impart sinusoidal movement to the plenum chamber, a plurality of air blowers disposed along the length of the vibratory plenum chamber in spaced apart relationship, each air blower being connected to each of the air compartments, the drying chamber having atleast one hood at the top thereof, atleast one cyclone separator connected to the hood and a water scrubber connected to the air outlet of the cyclone separator.
2. The sugar drier as claimed in claim 1, wherein the sugar feed means comprises a feed hopper and the sugar discharge means comprises a sugar outlet.
3. The sugar drier as claimed in claim 1 or 2, wherein the channel member is made of stainless steel and is mounted on stainless steel springs which in turn are supported on the support structure.
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4. The sugar drier as claimed in anyone of claims 1 to 3, which comprises three air blowers one of which is a hot air blower and is disposed at the inlet end of the plenum chamber and other two air blowers are cold air blowers disposed after the hot air blower.
5. The sugar drier as claimed in anyone of claims 1 to 4, which comprises three hoods and two cyclone separators which are connected to the hoods through a common duct extending along the length of the drying chamber.
6. The sugar drier as claimed in anyone of claims 1 to 5, wherein the drive means comprises an electric motor having a driver pulley mounted on the shaft thereof, a driven shaft disposed parallel to the motor shaft and rotatably mounted on a pair of spaced apart upright members, a driven pulley mounted on the driven shaft at one end thereof corresponding to the driver pulley on the motor shaft, the driver and driven pulleys being interconnected by a belt, a cam provided on the driven shaft and a cam follower engaged over the cam and connected across the support structure through a cross connector means.
7. The sugar drier as claimed in claim 6, wherein the cam is integrally formed on the driven shaft.
8. The sugar drier as claimed in claim 6 or 7, wherein the cam follower comprises a first bearing and the cross connector means comprises a crosspin rigidly connected across a bracket which in turn is connected across the support structure and a second bearing mounted on the crosspin and coupled to the first bearing.
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9. The sugar drier as claimed in any one of claims 1 to 8, wherein the support structure is provided with an access window.
Dated this 15th day of September 2008

(Prita Madan) ofKhaitan&Co
Kilburn Engineering Limited By their Agent & Attorney
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