FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
TITLE OF THE INVENTION
VIBRATORY FLUID BED DRYER FOR DRYING FERMENTED LEAVES
APPLICANT
Kilburn Engineering Limited
of Plot No. 6, MIDC Industrial Area, Saravali,
Kalyan Bhiwandi Road, Thane 421 311,
Maharashtra, India;
An Indian Company
The following specification particularly describes the invention and the manner in which it is to be performed

FIELD OF THE INVENTION:
The present invention relates to vibratory fluid bed driers for drying fermented tea leaves.
BACKGROUND OF THE INVENTION:
Tea leaves plucked from tea plants in tea gardens or plantations are initially withered in withering troughs by passing hot air there through. Withering gives an elastic or plastic texture to the leaves so as to prevent tearing and breaking thereof during further processing. Withered tea leaves are generally processed into cut tear curl (CTC) tea or orthodox tea. CTC tea is granular, whereas orthodox tea is leafy.
One such dryer has been disclosed in our Indian patent 197877. However, it has been noticed that in the dryer disclosed in Indian patent 197877 there are inherent problems like side and top fly off and development of higher resistance in cold air mixing chamber. Ifigh resistance in the cold air mixing chamber resulting in a higher pressure drop and this lead to improper mixing of hot air and cold air in that zone. Moreover, in the dryer disclosed in patent no. 197877 there is difficulty in maintenance of the motors of the top part of dust extraction system since there motors are not easily accessible from outside.
Therefore the inventor felt the need to first indentify the root cause of the problems associated with the dryer of Indian patent no. 197877. Accordingly the inventor carried out various experiments with the dryer of 197877. The inventor tried to determine the air flow rate through different sections of the dryer and thereby evaluate the pressure drop across the various cardinal points of the dryer, such as the plenum chamber damper, cyclone system, etc, in cold condition. However owing to the inherent complexity the inventor had to redesign their experimental strategy and decided to carry out the experiments under Toad' and no load condition of the dryer. The experimental results were taken in varying conditions and- at various places where tea is grown and manufactured. Thus the inventor had

to conduct rigorous experiments before they could determine the cause of problem of side and top fly off and higher air resistance that were prevalent in the dryer of 197877.
Upon having determined the cause of the problems associated with the dryer of 197877, the inventor has now developed an improved vibratory fluid bed dryer for drying fermented tea leaves having minimal or no side and top fly off together with lower resistance in cold air mixing chamber.
Advantageously, in the proposed dryer the motors of the dust extraction system have been disposed in such a way to make them easily accessible from outside.
SUMMARY OF THE INVENTION:
Accordingly, the present invention provides a vibratory fluid bed dryer for drying fermented tea leaves comprising a dryer assembly and a hot and cold air blower attached to said dryer for supplying hot air into said dryer; said dryer assembly comprises:
- a plenum chamber connected to said hot and cold air blower,
- a drying chamber disposed above said plenum chamber , said drying chamber having a feed end and a discharge end,
- a perforated sheet separating said plenum chamber and said drying chamber , said perforated sheet being configured to allow hot air to enter said drying chamber from said plenum chamber,
- a feed distributor disposed adjacent to the feeding end of said drying chamber for feeding fermented tea leaves into said drying chamber,
- a vibrating mechanism for setting said plenum chamber and in turn said perforated sheet into vibration,
- at least a dust-extractor-cum-refiring assembly for arresting side and top fly off of said tea leaves and/or tea dust particles from said drying

chamber, said dust-extractor-cum-refiring assembly being disposed above said drying chamber comprising :
- an exhaust duct provided with at least an axial flow fan for removing tea dust particles from said fermented tea leaves produced during drying the tea leaves, and,
- at least six axial flow cyclones for refiring tea leaves and/or tea dust particles back to the drying chamber and for allowing only hot air to escape from said dust-extractor-cum-refiring assembly,

- a cyclone blower disposed adjacent to discharge end of said drying chamber for collecting the tea dust, said cyclone blower being operatively connected to a cyclone system, and
- a discharge chute , disposed at the discharge end of said drying chamber, for collecting dried tea leaves from said drying chamber.
According to a preferred embodiment of the invention, said dryer is provided with a pair of said dust-extractor-cum-refiring assembly.
According to a particular embodiment of the invention, said hot air blower is a double inlet, double width blower. Preferably, said double width air blower is provided with two dampers for regulating the flow of said hot air into said dryer.
According to another embodiment of the invention, said vibratory fluid bed drier is provided with rotating mixer disposed within said drying chamber for mixing said fermented tea leaves.
According to yet another embodiment of the invention, said dryer assembly is provided with a cold air blower and a mixing chamber for mixing cold air generated from said cold air blower with hot air generated from said hot air blower, and wherein said hot air blower is a double inlet, double width blower and wherein said plenum chamber is partitioned in two compartments, a first compartment for letting in hot air from said hot air blower and a second compartment for letting in premixed

hot and cold air from mixing chamber. Preferably, in the invented fluid bed dryer, the motor of each of said exhaust ducts is disposed vertically outside said exhaust duct.
According to a further embodiment of the present invention, said drying chamber is provided with regions of increased drying surface area. Preferably, each upstanding walls of said drying chamber has an intermediate tapered section for increasing the drying surface area of said drying chamber.
According to still another embodiment of the present invention wherein said hot air blower is coupled to a heater for generating hot air. The hot air flowing out from said cyclone system may fed into said heater's suction end to save energy. Preferably, said plenum chamber is partitioned in two compartments, a first compartment for letting in hot air from said hot and cold air blower, and a second compartment for letting in premixed hot and cold air from the mixing chamber.
The inventor carried out various experiments to calculate variation in the capacity and water evaporation load with the variation in the dimension of the drying chamber for CTC as well as for orthodox tea leaves. The inventor assimilated the data obtained from these experiments to obtain a range for the capacity and corresponding range of water evaporation load for a given dimension of a drying chamber. The technical specifications of invented dryers when used for the production of CTC tea and for the production of orthodox tea have been shown, by way of example, in figures 13 and 15 respectively, for the purpose of non-limitative illustration only. The capacity chart for CTC tea and for orthodox tea has been graphically represented in figures 14 and 16 of the accompanying drawings, for examplary purpose only. The variation in capacity of made tea and in water evaporation load of the invented vibratory fluid bed dryer with the change in size of the drying chamber has been illustrated in Table I below, which is arrived at by combining the results obtained and shown in figures 13 and 15.

TABLE I

Size of Drying Chamber (MM x MM) CAPACITY
(Kg / hr.) (MADE TEA) Water evaporation Load (Kg. / hr.)
450 x4880 105-115 115-215
1185x6600 210-250 300-435
1185x8250 315-410 425-790
1755x8800 430-525 600-1155
1755x11200 650-770 860-1480
The capacity mentioned above has been calculated , considering that feed moisture of Said fermented tea leaves is maintained between 55% to 66 % W/B and the temperature of said hot air generated from said hot and cold air blower is maintained between 120°C to 140° C and altitude maintained upto 500 meters.from sea level. The capacity will vary with the change in inlet moisture, temperature and attitude of teas
BRIEF DESCRIPTION OF THE DRAWINGS:
For better understanding various embodiments of the invention will now be described with reference to the accompanying drawings. It will, however, be appreciated that the embodiments exemplified in the drawings are merely illustrative and not limitative to the scope of the invention, because it is quite possible, indeed often desirable, to introduce a number of variations in the embodiments that have been shown in the drawings.
In the accompanying drawings:
Figure 1 schematically shows an elevation view of a particular embodiment of the invented vibratory fluid bed dryer.

Figure 2 schematically shows the top view of a set of six axial flow cyclones as viewed from 'A-A' of Figure 1.
Figure 3 schematically shows an elevation view of a dust-extractor-cum-refiring assembly of the vibratory fluid bed dryer illustrated in figure 1.
Figure 4 schematically shows an elevation view of the axial fan motor for dust-extractor-cum-refiring assembly
Figure 5 shows an isometric view of the hot air blower used in the vibratory fluid bed dryer of figure 1
Figure 6 schematically shows an. elevation view of the mixing chamber with multiple louver dampers according to the particular embodiment of the invention.
Figure 7 schematically shows an isometric cutaway view of the dust extractor axial motor according to the particular embodiment of the invention.
Figure 8 schematically shows as elevation view of hot and cold air blower of the vibratory fluid bed dryer illustrated in figure 1.
Figure 8(a) schematically shows the aerodynamically designed cold air duct provided with the hot and cold air blower shown in figure 8.
Figure 9 schematically shows an elevation view of the drying and the plenum chambers.
Figure 9 (a) shows a view of the drying chamber taken at line B-B of figure 9.
Figure 10 schematically shows a perspective cutaway view of a set of six axial flow cyclones.
Figure 10(a) schematically shows the view of an axial flow cyclone taken at line E-E of figure 10.

Figure 11 schematically shows an isometric plan view of the drying chamber, according another embodiment of the invented vibratory fluid bed dryer, showing plenum chamber perforations and mixer.
Figure 12 schematically shows an elevation view of yet another embodiment of invented fluid bed dryer showing the hot air return from the cyclone system to the hot air blower.
Figure 13 illustrates the technical specifications of invented fluid bed dryers, having different dimensions, when used for the production of CTC tea, according to a particular embodiment of the invention.
Figure 14 graphically shows the capacity chart of invented fluid bed dryers of different dimensions when used for production of CTC tea.
Figure 15 illustrates the technical specifications of invented dryers, having different dimensions, when used for the production of orthodox tea.
Figure 16 graphically shows the capacity chart of invented fluid bed dryers of different dimensions when used for production of orthodox tea.
DETAILED DESCRIPTION OF THE DRAWINGS:
Referring to figure 1 of the accompanying drawing, the invented vibratory fluid bed dryer (1) for drying fermented tea leaves, according to a particular embodiment comprises a hot and cold air blower (2) and a dryer assembly (3); said hot and cold air blower (2) being attached to said dryer assembly (3) through a mixing chamber (4). Hot air from the blower (2) is mixed with cold air from the cold air blower (5) at the mixing chamber (4).
The dryer assembly (3) comprises a plenum chamber (6), connected to said hot and cold air blower (2), a drying chamber (7) disposed above said plenum chamber (6), a perforated sheet (8) separating said plenum chamber (6) and said drying chamber

(7), a feed distributor (9) provided to said drying chamber (7), a vibrating mechanism (10) attached to said perforated sheet (8), two rotating mixers (11) disposed inside said drying chamber (7), at least a pair of exhaust ducts (12) provided to said drying chamber (7), at least two sets of six axial flow cyclones (16), a cyclone blower (13) and a discharge chute (14) for collecting the dried tea leaves. The cyclone blower (13) is connected to the cyclone system (15).
The fermented tea leaves are fed into the drying chamber (7) by means of said feed distributor (9). Hot air from the plenum chamber (6) passes to the drying chamber (7) through the perforated sheet (8) and dries the fermented tea leaves that are conveyed through the feed distributor (9) into said drying chamber (7). The drying chamber (7) has a feed end adjacent to the feed distributor (9) and a discharge end adjacent to said discharge chute (14). The vibrating mechanism (10) vibrates plenum chamber (6) and in turn sets the perforated sheet (8) into vibration in such a way that the fermented tea leaves are set into a wobbling motion. The rotating mixers (11) inside said drying chamber (7), an isometric view of one of which is illustrated in figure 11, uniformly mix the tea leaves during drying of the tea leaves. The rotating mixers (11) are preferably driven by a motor drive. The pair of exhaust ducts (12) collect the tea dust produced during drying and reintroduce it to the drying chamber (7) and the cyclone blower (13) collects the tea dust at the end of the said drying chamber (7). The dried tea leaves are finally collected by the discharge chute (14). Each exhaust duct (12) together with its corresponding set of six axial flow cyclones (16) constitutes a dust-extractor-cum-refiring assembly (23), as shown in figure 3 of the accompanying drawings. Thus the dryer assembly (3) assembly is provided with a pair dust-extractor-cum-re firing assembly (23).
Referring to figures 2, 10 and 10(a) of the accompanying drawings, each set of six axial flow cyclones (16) are configured for refiring tea leaves and/or tea dust particles back to the drying chamber (7) and allow only hot air to escape from said dust-extractor-cum-refiring assembly (23) (as shown in figure 3). The axial flow cyclones (16) arrest the side and top fly off the tea leaves during the drying process.

The axial flow cyclones (16) act to return those tea leaves that attempt to fly off from the top and sides of the drying chamber (7) back into the drying chamber (7). The dryer (1) is mounted on a main frame (17).
In the invented fluid bed dryer (1) the motor (18) of each exhaust ducts (12); i.e. the motor of the duct extraction system is disposed at the top of the exhaust duct (12) as seen in figures 1, 3 and 4 of the accompanying drawings. This makes the motors (18) easily accessible to the maintenance personnel. The axial fan motor
(24) for dust-extractor-cum-refiring assembly (23) has been shown in figures 3 and
4 show the axial fan motor (24) for dust-extractor-cum-refiring assembly (23). A
cutaway view of the dust extractor axial fan (24) has been shown in figure 7.
Figure 5 shows an enlarged view of the hot and cold air blower (2). The hot and cold air blower (2) has an inlet (19) point and an outlet (20) point. The mixing chamber (4) is provided with multi-louver dampers (21) to control air mixing, as can be seen in figure 6. As seen in figure 8 and 8(a), the mixing chamber is provided with aerodynamically designed cold air duct (22) to assist correct mixing of the air from the hot and cold air blower (2) and cold (5) air blower (shown in figure 2 only).
The drying chamber (7) is provided with regions of increased drying surface area. As seen in figure 9(a) of the accompanying drawings each upstanding side walls
(25) of said drying chamber (7) has an intermediate tapered section to increase
drying surface area of the vibratory fluid bed dryer (1).
Figure 12 illustrates another embodiment of the invented vibratory fluid bed dryer (1). In this embodiment the hot air that comes out from the cyclone system (15) is feed back to the heater (26) of the hot and cold air blower (2) to reduce fuel consumption of the drier (1).
As seen in figure 9 of the accompanying drawings, the plenum chamber (6) is partitioned in two compartments, a first compartment (27) for letting in hot air from

said hot and cold air blower (2) and a second compartment (28) for letting in premixed hot and cold air from the mixing chamber (4).
As already mentioned, the foregoing description is illustrative of the invention and not limitative to its scope, because it will be apparent to persons skilled in the art to device other alternative embodiments without departing from the broad ambit of the disclosures made herein.

WE CLAIM
1. A vibratory fluid bed dryer for drying fermented tea leaves comprising a dryer assembly and a hot and cold air blower attached to said dryer for supplying hot air into said dryer; said dryer assembly comprises:
- a plenum chamber connected to said hot and cold air blower,
a drying chamber disposed above said plenum chamber , said drying chamber having a feed end and a discharge end,
a perforated sheet separating said plenum chamber and said drying chamber, said perforated sheet being configured to allow hot air to enter said drying chamber from said plenum chamber,
a feed distributor disposed adjacent to the feeding end of said drying chamber for feeding fermented tea leaves into said drying chamber,
a vibrating mechanism for setting said plenum chamber and in turn said perforated sheet into vibration,
at least a dust-extractor-cum-refiring assembly for arresting side and top fly off of said tea leaves and/or tea dust particles from said drying chamber, said dust-extractor-cum-refiring assembly being disposed above said drying chamber comprising :
- an exhaust duct provided with at least an axial flow fan for removing tea dust particles from said fermented tea leaves produced during, drying the tea leaves, and,
- at least six axial flow cyclones for retiring tea leaves and/or tea dust particles back to the drying chamber and for allowing only hot air to escape from said dust-extractor-cum-refiring assembly,

- a cyclone blower disposed adjacent to discharge end of said drying chamber for collecting the tea dust, said cyclone blower being operatively connected to a cyclone system, and
- a discharge chute , disposed at the discharge end of said drying chamber, for collecting dried tea leaves from said drying chamber.

2. The vibratory fluid bed dryer as claimed in claim 1, wherein said dryer is provided with a pair of said dust-extractor-cum-refiring assembly.
3. The vibratory fluid bed dryer as claimed in any of the above claims 1 and 2, wherein said hot air blower is a double inlet, double width blower.
4. The vibratory fluid bed dryer as claimed in claim 3, wherein said double width air blower is provided with two dampers for regulating the flow of said hot air into said dryer.
5. The vibratory fluid bed dryer as claimed in any of the above
claims, wherein said vibratory fluid bed dryer is provided with rotating mixer
disposed within said drying chamber for mixing said fermented tea leaves,
6. The vibratory fluid bed dryer as claimed in any of the above
. claims, wherein said dryer assembly is provided with a cold air blower and a
mixing chamber for mixing cold air generated from said cold air blower with hot air generated from said hot air blower, and wherein said hot air blower is a double inlet, double width blower and wherein said plenum chamber is partitioned in two compartments, a first compartment for letting in hot air from said hot air blower and a second compartment for letting in premixed hot and cold air from mixing chamber.
7. The vibratory fluid bed dryer as claimed in any of the above
claims, wherein the motor of each of said exhaust ducts is disposed vertically
. outside said exhaust duct.
8. The vibratory fluid bed dryer as claimed in any of the above
claims, wherein water evaporation load of said fluid bed dryer varies from 115
kg/hr to 215 kg/hr and wherein said fluid bed dryer is configured to produce
105 kg to 115 kg of dried fermented tea leaves per hour, considering that feed

moisture of said fermented tea leaves is maintained between 55% to 66 % W/B and the temperature of said hot air generated from said hot and cold air blower is maintained between 120°C to 140° C and altitude maintained upto 500 meters from sea level.
9. The vibratory fluid bed dryer as claimed in claim 8, wherein the dimension of said drying chamber is 450 mm X 4880 mm.
10. The vibratory fluid bed dryer as claimed in any of the above claims, 1 to 7 wherein water evaporation load of said fluid bed dryer varies from 300 kg/hr to 435 kg/hr and wherein said fluid bed dryer is configured to produce 210 to 250 kg of dried fermented tea leaves per hour , considering that feed moisture of said fermented tea leaves is maintained between 55% to 66 % W/B and the temperature of said hot air generated from said hot and cold air blower is maintained between 120°C to 140° C and altitude maintained upto 500 meters from sea level.
11. The vibratory fluid bed dryer as claimed in claim 10, wherein the dimension of said drying chamber is 1185 mm X 6600 mm.
12. The vibratory fluid bed dryer as claimed in any of the above claims, 1 to 7 wherein water evaporation load of said fluid bed dryer varies from 425 kg/hr to 790 kg/hr and wherein said fluid bed dryer is configured to produce 315 kg to 410 kg of dried fermented tea leaves per hour, considering that feed moisture of said fermented tea leaves is maintained between 55% to 66 % W/B and the temperature of said hot air generated from said hot and cold air blower is maintained between 120°C to 140° C and altitude maintained upto 500 meters from sea level.
13. The vibratory fluid bed dryer as claimed in claim 12, wherein the dimension of said drying chamber is 1185 mm X 8250 mm.

14. The vibratory fluid bed dryer as claimed in any of the above claims, 1 to 7 wherein water evaporation load of said fluid bed dryer varies from 600 kg/hr to 1155 kg/hr and wherein said fluid bed dryer is configured to produce 430 kg to 525 kg of dried fermented tea leaves per hour, considering that feed moisture of said fermented tea leaves is maintained between 55% to 66 % W/B and the temperature of said hot air generated from said hot and cold air blower is maintained between 120°C to 140° C and altitude maintained upto 500 meters from sea level.
15. The vibratory fluid bed dryer as claimed in claim 14, wherein the dimension of said drying chamber is 1755 mm X 8800 mm.
16. The vibratory fluid bed dryer as claimed in any of the above claims, 1 to 7 wherein water evaporation load of said fluid bed dryer varies from 860 kg/hr to 1480 kg/hr and wherein said fluid bed dryer is configured to produce 650 kg to 770 kg of dried fermented tea leaves per hour , considering that feed moisture of said fermented tea leaves is maintained between 55% to 66 % W/B and the temperature of said hot air generated from said hot and cold air blower is maintained between 120°C to 140° C and altitude maintained upto 500 meters from sea level.
17. The vibratory fluid bed dryer as claimed in claim 16, wherein the dimension of said drying chamber is 1755 mm X 11200 mm.
18. The vibratory fluid bed dryer as claimed in any of the above claims, wherein said drying chamber is provided with regions of increased drying surface area.
19. The vibratory fluid bed dryer as claimed in claim 18, wherein each upstanding walls of said drying chamber has an intermediate tapered section for increasing the drying surface area of said drying chamber.

20. The vibratory fluid bed dryer as claimed in any of the above claims, wherein said plenum chamber is partitioned in two compartments, a first compartment for letting in hot air from said hot and cold air blower, and a second compartment for letting in premixed hot and cold air from the mixing chamber.
21. The vibratory fluid bed dryer as claimed in any of the above claims, wherein said hot air blower is coupled to a heater for generating hot air.
22. The vibratory fluid bed dryer as claimed in claim 21, wherein said hot air flowing out from said cyclone system is fed into said heater's suction end.