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(11) Patent Number: KE 401   

(51) Int.CI.8: A 23F 3/00

(ll)Application Number: IUE/P/2005/000462

(22) Filing Date: 16/09/2005

(30)    Priority data:  !761/DEU2004  17/0912004  IN

(73) Owner:COUNCIL OF SCIENTIFIC AND INDUSTRIAL

RESEARCH of  Anusandhan Bhavan I, Rafi Marg, New

Delhi 110001, India

(72) Inventor:

GARIKAPATI, Dyva, Kiran, Babu of Institute of Himalayan Bioresource Technology, Post Box No. 6, Palampur, Himachal Pradesh 176 061 India;

DESIKACHAR, Ravindranath, Srigiripuram of Institute of Himalayan Bioresource Technology, Post Box No.6,

Palampur, Himachal Pradesh 176 061 India; KAR.,
Arindam of MIS Mesco Equipment (P) Ltd 2A Ganesh
Chandra A venue, Comerce House, 9th Floor, Flat SA

Kolkata, 700 013 India aod Maji Pankaj Kumar Of MIS

Mesco Equipment (P) Ltd 2A Ganesh Chandra Avenue,

Comerce House, 9th Floor, Flat 5A Kolkata, 700 013, India

(74) Agent/address for correspondence:

Waruinge & Waruinge Advocates, P. 0. BOX 72384, Nairobi
 

(54)Titie: A MOBILE TEA SHOOT PRECONDITIONING DEVICE FOR WITHERING DURING BLACK TEA MANUFACTURE

(57) Abstract:The mobile tea shoot preconditioning device of the present invention for withering during black tea manufacture comprises of a super structure consisting in combination a base plate mounted crank shaft mechanism, a plurality of pressure pads mounted at different heights and an anti-presswe plate consisting of a rigid top supporting an endless conveyor belt. The base plate having the crank shaft mechanism is capable of providing vertical relative movement between the anti-pressure plate consisting of a rigid top supporting an endless conveyor belt on which the tea shoots are placed in such a manner that the tea shoots on the said conveyor receives desired pressure through a plurality of pressure pads mounted at different heights on the super structure. The present invention provides a mobile tea shoot preconditioning device for withering during black tea manufacture which helps in reducing the total process time coupled with reduction in energy usage and is capable of working in continuous mode, resulting in enhanced productivity.

The present invention relates to a mobile lea shoot pre-con~ll~l-or

. withering during black tea manufacture. The present invention part,ca lji-•1 '% to a device which is mobile and helps in reducing the withering process time during black tea manufacture and also enhances productivity by enabling

5    processing in continuous mode. Thus, saving on the total manufacturing time and energy.

The  present  invention  is  particularly  useful  during  the process of black tea

manufacture from tea shoots harvested from bushes of Camellia sinensis (L) 0 1o   Kuntze as soon as possible at the field or arrival at the factory. The use of the device of the present invention enhances the rate of physical and chemical wither needed for the development of chemical attributes essential for making black teas, both orthodox and fragmented CTC teas.  The use of this device will also cut down the withering time from the conventional 10 to 20 hours to 4 Y, to 5 Y,

15    hours depending on the type of black tea to be made. Other benefits of using this device will result in saving of factory space needed for processing additional tea shoots that usually arrive at the factory during rush period. Since the preconditioning of tea shoots eliminates use of warm air used for achieving

physical and chemical withers, there is further saving on the energy to be used

20 during black tea processing. With suitable modification and addition, black tea manufacture can be made continuous, once the shoots are brought to the tea

, factory.


Reference  may  be  made  to  the  conventional,  hitherto  known  methods  of 25   processing  of tea  shoots to black tea,  both  orthodox and fragmented  CTC, involves several steps of which the most critical but time consuming step is
'withering'.During this step the tea shoots are allowed to undergo chemical changes called 'chemical wither' brought out through biochemical reactions inherent to shoots by spreading in open troughs or closed troughs in layers

30    through which either ambient or warm air is circulated respectively. The shoots are allowed to stay in troughs for 16 to 20 hours in case of open troughs and 10

to 12 hours in closed troughs to achieve the chemical wither needed for making black teas of desirable character or quality.

Reference may be made to patent no.:  GB2157409, wherein is described a

5    device for withering tea leaves continuously, which comprises a chamber having an inlet end and an opposite end, said chamber being provided with guide rails
for accommodating a plurality of trays in two (or more pairs of) runs. The trays are disposed in an inclined manner. A duct is provided for forcing hot air into said chamber, and there are also means for moving said trays through said chamber, 1o   means for carrying said trays at the end of a run to the next lower run, means, for returning  trays  through  a  lower  run,  and  means  for  lifting  said  trays  after discharging the withered tea leaves to the top run where green tea leaves are fed.

Reference may be made to patent no.:GB633261, titled: Improvements in and

15    relating to the withering of tea, wherein tea is artificially withered by mechanic-ally milling the leaf with sufficient force to bruise it without crushing it, and then treating it under vacuum in a closed vessel internally heated to a temperature

approaching but not exceeding 100 F. Tea leaf is spread by a paddle-type device

12 over a belt conveyor 10 which feeds the leaf between a pair of oppositely

20    rotating fluted rollers 1 pressed together by spring means 2. The milled leaf is discharged into a vessel 3 provided with detachable covers 4 and 5, an internal heating coil 6 and a vacuum pump 19. The vessel, when full, is sealed and subjected for a period of 2 to 4 hours to a minimum vacuum of 16 inches of Hg., the maximum inlet temperature of the heating medium being 100 F.

25

Reference may be drawn to a tea withering apparatus disclosed in patent no.: GB460891, wherein is described a lea-withering installation which comprises a main withering loft having a separate withering chamber therein through which, in respect of the feeding or discharge of the tea leaf to or from the withering loft and
30    the separate •com- partment, the tea leaf moves in a direction transverse to the direction of movement of the tea leaf through the main loft, a unidirectional fan or
 
like device being disposed in the roof of the loft above the compartment so as to deliver drying medium thereto. There may be several such compartments each with a fan.

5 Reference may be made to patent no.:GB439952, wherein is disclosed a method of withering tea in a loft, air is circulated through the loft and its hygrometric state at entry is controlled to maintain as nearly as possible a predetermined ability to take up moisture at a point reached after passing the whole or a predetermined portion of the leaf in the loft, the arrangement being such that, if the air supplied

10 in the moistest of three or more alternative conditions gives a moisture-absorbing capacity below that predetermined at the point in question, a correction is applied causing drier but not substantially warmer air to be admitted, and if after this correction has been applied, the moisture-absorbing capacity is still below that predetermined at the point in question, a correction of a different kind is applied

15    still causing the air admitted to be drier whether or not it is warmer.

A further reference may be made to patent no.: GB189800314, which relates to apparatus for withering tea, which comprises a fixed ex1ernal casing and a frame

adapted to be rotated on an axis and serving as a support for tiers of perforated

20    trays on which the tea is laid. The apparatus may be covered with a piece of fabric stretched on the ring Hand serving to check the passage of air through the apparatus. The air, which may have Leen moistened by passing through damped tex1ile material, is forced into the apparatus through a pipe. The apparatus is fitted with a lifting-device by which the frame and its appendages can be lifted out

25    of the casing.


Reference may also be made to patent no.: GB189701406, titled: Improved apparatus for withering tea, and for various drying purposes, in which swinging trays are hinged at the bottom and can be raised, suspended, or turned over by

30    means of ropes or cords wound upon a roller or windlass, or any other device may be used to simu~aneously control the trays. In withering tea, these trays are
 
first made to recline downwards, and each is swung over in turn and the tea leaf spread out on it. The air-distributing system consists of a main pipe under the trays or frames, having nozzles or orifices, which discharge hot air upon the deflecting-boards to equally disperse the air current. By these arrangements,

5    vapour can escape from both sides of the trays without passing through the material under treatment. When the drying process is completed, the swinging

trays are raised to a vertical position and the material falls down upon the floor beneath, where sheets may be spread and arranged to run upon rollers to collect and bring in the material under treatment.
10

Reference may be made to M.G. Hampton. Green and semi-fermented teas. (In) Tea: Cuffivation to consumption. Chapter 14, K.C. Wilson and M.N. Clifford (eds.), Chapman & Hall: London, UK, 1992; 478-481, wherein the need for chemical wither and withering methods followed in factories by using different systems was

15    discussed. In open trough system, the tea shoots are spread in thin (25 to 50 mm thick) layers on shelf/bamboo racks fitted with Hessian or suitable perforated mesh and ambient air is passed through the system for 16 to 20 hours depending on the type of shoots and ambient conditions like temperature and humidity,

before further processing the shoots.  A variation of true open system is the open

20    trough in which the shoots are stored in cement structures called 'troughs'fitted with suitable mesh (about 32 perforation/in2) in 225 to 300 mm thickness. At one end of the trough, a fan is provided which can either force the circulation of ambient air or preheated/warm air through the system. This improvement reduced the space needed for storing the leaf for withering. However, the basic

25    time requirement of 16 to 20 hours is still not reduced. Further, in 'closedtrough' system the 'opentrough'is enclosed with windows and doors for circulation and operations. Mainly due to better control over the conditions, there is slight improvement in 'witheringconditions'resulting in reduction of withering time to around 10 to 12 hours.
30

The major drawbacks of the trough systems are that (i) the length of withering time is too long i.e., 10 to 20 hours before the shoots can be taken up for further processing, (ii) on high humidity or rainy or cold days when the temperatures are low, the time needed for withering are much longer, beyond 20 hours. (iii) The
5    ambient air on such days also needs to be heated or mixed with separately heated air to remove the moisture thus requiring additional energy and expenditure, (iv) the surface moisture due to morning dew or rain during days of plucking makes it necessary to remove the excess moisture/water separately for achieving unifonnity in withers, (v) due to uneven flow of harvested shoots during

1o    the seasons,. there are lean and rush days for the crop.  On rush days, the

amount of shoots invariably exceeds the existing capacity of trough  and the

factories are forced to go behind the schedule of the processing or process in

haste to produce teas of inferior quality.


15    Reference may also be made to the Indian Patent no. 187299 titled: Improved process for the manufacture of tea, wherein a process facilitated the reduction in withering time to 4 Y, to 5 Y, hours using only ambient air to achieve both

physical and chemical withers at the same time.   This patent suggested the

usefulness in tea manufacture and highlighted the advantages of saving energy

20    needed for heating ambient air, shortened withering time, increasing availability of factory space needed for withering and better utilization of both factory and labour/manpower. The major drawback in this method was that bei~g a manual, labour intensive procedure, application was not possible to process thousands of kg of green tea shoots handled on a daily basis even in normal sized factories.
25

From the hitherto known art, as herein above described, it is seen that these suffer from one or the other major drawbacks like (i) space constraint (ii) long leaf storage time (iii) need to use warm air to remove surface moisture, (iv) wastage of energy and machine time and manpower or (v) limiting the usefulness only to

30    small scale manufacture. Hence, there is a definite need to provide a tea shoot pre-conditioning device for withering during black tea manufacture.
 
The main object of the present invention is to provide a mobile tea shoot pre-conditioning device for withering during black tea manufacture, which obviates the drawbacks of the hitherto known prior art as detailed above.
5    Another object of the present invention is to provide a device for use as a tea shoot pre-conditioner that can increase the throughput and meet the requirement of normal sized factories at higher scale.

Still another object of the present invention is to develop a device which can have

10    flexibility of throughput of the pre-conditioned tea shoots to suit the needs of tea factories.

Yet another object of the present invention is to develop a device which can save on energy requirement during withering of tea shoots.

15

Another object of the present invention is to help the factories to process tea shoots in a shorter duration of time, w~hout loss in quality.

Yet another object of the present invention is to enable tea factories to overcome

20    limitations over leaf storage space faced during rush/glut crop periods.


Still another object of the present invention is to yield a choice of putting the device on wheels to make it mobile or grouted to the ground.

25    The mobile tea shoot pre-conditioning device of the present invention for withering during black tea manufacture comprises of a super structure consisting

in combination a base plate mounted crank shaft mechanism, a plurality of pressure pads mounted at different heights and an anti-pressure plate consisting of a rigid top supporting an endless conveyor belt. The base plate having the
30    crankshaft mechanism is capable of providing vertical relative movement between the anti-pressure plate consisting of a rigid top supporting an endless

conveyor be~ on which the tea shoots are placed in such a manner that the tea shoots on the said conveyor receives desired pressure through a plurality of pressure pads mounted at different heights on the super structure. The present invention provides a mobile tea shoot preconditioning device for withering during black tea manufacture which helps in reducing the total process time coupled with reduction in energy usage and is capable of working in continuous mode, resuHing in enhanced productivity.

The device of the present invention is particularly useful during the process of

10    black tea from tea shoots harvested from bushes of Camellia sinensis (L) 0. Kuntze as soon as possible at the field or arrival at the factory. The device is a mobile unit capable of varying the throughput between the range 1000 to 6000 kg/hr. The use of the device enhances the rate of physical and chemical wither needed for the development of chemical attributes essential for making black

15    teas, both orthodox and fragmented CTC teas. The use of device also cuts down the withering time from the conventional 10 - 20 hrs to 4 Y, - 5 Y, hours, depending on the type of black tea to be made. other benefits of using the device are saving of factory space needed for processing additional tea shoots

that usually arrive at the factory during rush period.  Since the pre-conditioning of

20    tea shoots eliminates use of warm air used for achieving physical and chemical withers, there is further saving on the energy to be used during black tea processing. With suitable modification and addition, black tea manufacture can be made continuous, once the shoots are brought to tea factories.

25    Accordingly the present invention provides a mobile tea shoot pre-conditioning device for withering during black tea manufacture, which comprises a super

structure consisting of three modules: (i) a horizontal rigid base plate having a

variable  crankshaft  mechanism,  (ii)  a  plurality  of  pressure  pads  unevenly

mounted in a variable gradient and (iii) an anti-pressure plate consisting of a rigid

30    top supporting a variable speed endless conveyor belt capable of holding tea shoots; the said modules being mounted in combination on to the said super
 
structure in such a manner that the said base plate mounted crank shaft mechanism is capable of providing relative vertical movement between the said plurality of pressure pads unevenly mounted in a gradient and the tea shoot carrying endless conveyor belt mounted on the said anti-pressure plate.

In an embodiment of the present invention, the variable crankshaft mechanism is capable of providing 24 to 36 vertical movements per minute.

In  another  embodiment  of  the  present  invention,  the  variable  crankshaft

10    mechanism is provided with an adjustable crank plate with slots to vary the crank centers.

In yet another embodiment of the present invention, the variable crankshaft mechanism is provided with a reduction gear box or belt drive or chain drive or hydraulic system.

15

In still another embodiment of the present invention, the variable speed endless conveyor belt is driven by a drum type motor with variable speed of up to 40 rpm or by reduction gear box drive with mechanized speed variator or by steep pulley arrangement

20

In still yet another embodiment of the present invention, the variable speed endless conveyor belt is made up of material such as polyvinyl chloride (PVC) or fiber reinforced with rubber, nylon, metal reinforced fiber.

25    In another embodiment of the present invention, the rigid top of the anti-pressure plate is made of wooden planks or non-rusting material such as stainless steel, aluminum, brass, galvanized iron, alloys of steel, high density polyethylene

(HOPE).

In a further embodiment of the present invention, the said pressure pads is made up of non-rusting material such as stainless steel, galvanized iron, brass, copper, alloys of copper and stainless steel with or without Teflon coating.

In a still further embodiment of the present invention, the height of the plurality of pressure pads unevenly mounted in a variable gradient is adjusted singly or in groups.

In a yet further embodiment of the present invention, the height of the plurality of pressure  pads  unevenly  mounted  in  a  variable  gradient  in  relation  to  the 1o   conveyor belt is varied to impart pressure in a range between 50 to 150 gm/cm2

on to the tea shoots being carried on the said conveyor belt.

In another embodiment of the present invention, the rigid top supporting a variable speed endless conveyor belt is provided at the tea shoot charging end
15    with a detachable feed regulator.

In still another embodiment of the present invention, the super structure is provided with one or more pressure pad modules coupled with anti-pressure plate module in multi-tier configuration.

20

In the drawings accompanying the specification an embodiment of the device of the present invention is described.

Figure 1 of the drawings represents the side view of the device of the present

25    invention comprising of a super structure having in combination of a base plate (1, 7,8,9, 19,27) provided with a variable crank mechanism (2,3,4,5,6, 17,28) connected to an anti-pressure plate mechanism (10,11,12,13,14,15,16,18,26,29)

consisting of a rigid top (13) supporting an endless conveyor assembly (10, 11, 12, 16) and a plurality of pressure pads unevenly mounted in a variable gradient

30    (15,20,21,22,23,24,25,26).
 

Figure 2 of the drawings represents the front view of the device of the present invention consisting of the assembly depicted in figure 1.

In yet another embodiment of the present invention, the device comprises a super structure having in combination a base plate (1,7,8,9,19,27) provided with a variable crank mechanism (2,3,4,5,6, 17,28) connected to an anti-pressure plate mechanism (10,11,12,13,14,15,16,18,26,29) consisting of a rigid top (13) supporting an endless conveyor assembly (10, 11, 12, 16) and a plurality of pressure pads unevenly mounted in a variable gradient (15,20,21,22,23,24,

1o 25,26), wherein a crank drive (2) and electric motor (3) are mounted through supporting plate (9) on to the rigid base plate (1), the said crank drive (2) is connected to an electric motor (3) through coupling attachment (4), drive shaft (5) mounted on reduction gear box (6) fixed on horizontal cross members (7) and intermediate up-right members (8) fixed on the said rigid base plate (1); the said

15    anti-pressure plate mechanism (10,11,12,13,14,15,16,18,26,29) consists of endless conveyor belt (1 0) on adjustable electronically speed regulated drum type motor drive (11) at discharging end and an idle conveyor roller (12) at charging end supported by rigid top (13) at the bottom, a detachable hopper/bin
(14)    with side guard provided with up-rights (15) of varying lengths covering the

20    said entire conveyor belt from both sides and whole assembly is fixed on a movable horizontal frame work (16), the said movable horizontal frame work (16) is attached to the said crank system (2 and 28) through a vertical rod (17) and

attached through carrying springs (18) to the upper member (19) of the said rigid base plate (1); the plurality of pressure pads unevenly mounted in a variable

25    gradient (15,20,21,22,23,24,25,26) is provided with a pressure pad carrying structure (20) consisting of pressure pads (21) tightened on sustained shafts (22) with pressure adjusting springs (23) mounted for free movement of said shafts

(22) and sustained internal (24) and external (25) bolts is welded or bo~ed through up-rights (26) on the said upper members (19) of the said base plate (1)

30    provided with wheels (27) for mobility.


In still another embodiment of the present invention, the rigid top (13) is attached to the movable horizontal frame work (16) by up-rights (29).

In still yet another embodiment of the present invention, the carrying springs (18) used to attach the said movable horizontal frame work (16) and the upper member (19) of the rigid base plate (1) is of flat or coil type.

In a further embodiment of the present invention, the height of pressure pad (21) is adjusted independently or in combination by means of internal (24) and/or

10    external (25) sustained bolts.

The constructional features of the device of the present invention depicted in figures 1 and 2 of the drawings, are as detailed below:

The device is a three layered/tiered open ended cage/tubular structure consisting

15    of base frame super structure assembly, assembly for moving conveyor and for pressure pad carriage system held together by a lower base member frame work, upper member frame work, intermediate upright member, upright carriage pressure pad, uprights to carry the anti-pressure plate. The upright members and uprights are welded or bolted at suitable intervals to hold the structures are

20    made of non-rusting steel or metal alloys of suitable size. The base frame super structure assembly has the super structure and housed the base frame for carrying the drive arrangement, cross member carrying the bridge block, drive shaft mounted on bridge bearing and adjustable crank plate with slots to vary the

crank centers, large end on pin to carry the connecting rod with adjustable crank

25    centers, large end carrying pin and coupling to attach gear box shaft to a 3 hp electric motor (1440 rpm) and a worm reduction gear box (40:1). The details of the parts of device are given as below :

A rigid base plate/member (1) of suitable shape such as square/round rods or

30    square/round tubes, channels etc., made up of cast iron or MS or alloy steel with L=2000 - 5500 mm or more, thickness = 5 to 20 mm is welded or bolted to the


horizontal cross members (7), L=850- 2500 mm of suitable material such as SS, MS, Cl, or alloys of non-rusting iron/copper and grouted to the floor through suitable foundation bolts or can be put on wheels (27) Diameter = 200 - 400 mm of SSIMS for easy mobility. The said super structure is primarily used for holding/supporting the entire device including 3 phase electric motor (3) of 2- 5 hp, 1440 rpm, fixed/adjustable crank drive (2) with slots to vary the crank centre is coupled (4) with suitable worm reduction (40:1) gear box (6) through a drive shaft (5) and attached to a vertical rod (17), L=400- 600 mm. The variable crank mechanism (2, 3, 4, 5, 6, 17 and 28) is fixed to the lower base plate (1, 7, 8,

10    9, 19 and 27) of the super structure with motor supporting plate (9) of suitable dimensions. The rigid base plate (1) of the super structure is further welded or bolted to the intermediate up-right members (8) of suitable height to

accommodate a  plurality of pressure  pads  unevenly  mounted  in  a  variable

gradient (15, 20, 21, 22, 23, 24, 25 and 26) with pressure pad carriage (20),

15    L=1100 - 3500 mm, W=800 - 2600 mm, thickness= 5 to 20 mm of suitable shape like angle iron, round/rectangular tubes/rods, channels made up of Cl, MS,

alloys of SS or copper is welded/bolted to upper member (19), L=2000- 5500 mm, thickness= 5 - 20 mm of super structure through up-rights (26) height=550 - 1600 mm of 6- 12 Nos., or more on both sides of suitable shape like angle

20    iron, round/rectangle tube/rods, channels made up of Cl, MS, alloys of iron/copper for carrying the pressure pads (21), L=650- 2000 mm, W=140- 500 mm, thickness= 50 - 200 mm, of 4 - 12 Nos., or more of suitable shape

preferably of rectangle made up of alloys of SS/copper without or with Teflon coating and each pad weighing 30-60 kg. The pressure pads (21) are attached

25    to threaded suspended/sustained shafts (22), 25 - 50 mm diameter, suitable lengths of 4 Nos., per pad with provision to vary the height of the pressure pad (21) from 75- 350 mm. Pressure control springs (23) compatible with diameter of suspended shaft (22) and internal (24) and external (25) sustained bolts - 4

Nos., each are attached to each comer of the rectangular pressure pad (21).

30    One end of vertical rod (17) is attached to crank system (2 and 28) and the other end is bolted to movable horizontal frame work (16), L=1950- 4900 mrn, W=700

-    2000 mm.  An adjustable electronically speed regulated drum type motor drive

(11)    with variable drive of any range 0-40 rpm or reduction gear box drive with mechanized speed variator, or step pulley arrangement is operated by suitable control box incorporating frequency converter and attached to movable horizontal frame work (16) and conveyor belt (10) of endless length L= 3100-9000 mm, W=700 - 2000 mm, thickness=3 - 7 mm made up of PVC, rubberized fiber, nylon or metal reinforced fiber. An idle conveyor roller (12) for carrying the

conveyor belt (1 0) is attached at a distance of 1550 - 4500 mm from electronically controlled conveyor drive (11). A rigid top (13), L=1350- 4300 mm,
10    W=700- 2000 mm, made up of wooden planks or any non-corrosive metals or metal alloys without or with Teflon coating is placed below the conveyor belt (10). The whole system, comprising of conveyor belt (10), rollers (11 and 12) rigid top

(13) is placed on movable horizontal frame work (16). The detachable hopper/bin (14) having L=1550- 4500 mm, W=775- 2500 mm, thickness= 2- 5

15    mm, made up of wooden plank or anti-rusting alloy of iron and copper is mounted on movable horizontal frame work (16) with the help of uprights (15) of varying heights. The comers of movable horizontal frame work (16) is also fixed to upper member (19) frame work with the help of four numbers or more flat or coil type

carrying springs (18).  Feeding hopper (14) is attached to removable side guards

20    and detachable feed regulator. The rigid top (13) is attached to upper member (19) of the super structure through uprights (29) of appropriate height made up of any non-corrosive metal(s) or alloy(s).

Advantage  is  taken  of the  enhanced  metabolic  ability  of tea  shoots  under

25    stressed conditions. Stress is given to the tea shoots by applying controlled pressure (physical) repeatedly. This controlled stress triggers enhanced metabolic activity resulting in utilizing the chemical components present in the leaves and stems of the shoots. Because of control over the application of stress,

the shoots are intact with no breakages and look just like the shoots before the

30    application of stress. The biochemical reactions, in addition to bringing about the chemical changes, also generate heat which needs to be removed by circulation

of unheated ambient air rather than use warm or heated air to remove moisture which is the normal practice in open or closed trough system described in prior art. Desired chemical changes called 'chemicalwither'is thus achieved in the stressed tea shoots along with the desired loss of moisture from the shoots called 'physicalwither'in a much shorter time (4 Y, to 5 Y, hours) compared to 10 - 20 hours in prior art. The device has versatility to vary the throughput of preconditioning of tea shoots from 1000 kg to 6000 kg per hour and can be moved from place to place within the factory/field to suit the convenience. By attaching the device to a conveyor system, which can also act as a withering

1o trough and synchronizing with other processing machines in the tea factory, it is possible to make tea processing continuous once the shoots arrive at the factory, thus, converting the batch type/discontinuous tea processing into continuous mode. The invention helps in cutting power requirements needed for warming the air used during 'withering'Through. the use of the invention rush period crop

15    can be processed easily. By rescheduling the processing, the factories with the help of invention, can process fifty percent more crop with the existing infrastructure and manpower. All these result in cutting down the unit cost of manufacture of tea and hence, increase the profitability to the factories.

20    The novelty of the present invention resides in providing a mobile tea shoot preconditioning device which cuts down on the withering process time during black tea manufacture at an enhanced level of productivity both for batch processing and for processing on continuous basis.

25    The novelty of the present invention has been realized by providing a device capable of imparting pre-determined pressure at a desired rate on to tea shoots moving on a conveyor belt supported by a rigid top, wherein the non-obvious inventive steps are: providing a super structure consisting of three modules which in combination constitute the device of the present invention. The three

30    modules are: (i) a horizontal rigid base plate having a variable crank shaft mechanism, (ii) a plurality of pressure pads unevenly mounted in a variable

gradient and (iii} an anti-pressure plate consisting of a rigid top supporting a variable speed endless conveyor belt capable of holding tea shoots.

The following examples are given by the way of illustration of the present invention in actual practice and therefore should not be construed to limit the scope of the present invention.

In the following examples fresh tea shoots 1000 kg to 3000 kg harvested from tea plantation comprising of 40 - 85 % two and a bud was charged into the bin

10    (14) located at the charging end of the device and was loaded on to the device manually over the period of operation. Prior to the starting of the device the crank (2} was raised to its top dead centre of 350 mm from a possible range of

75 -  350 mm.  The speed of the crank was regulated in the range 12 -  30

cycles/min with help of appropriate reduction gears (6).  The pressure pads (21)

15    starting from feed end to discharge end were fixed at 250- 225- 200- 175-150 - 125 mm from crank bottom dead centre with the help of pressure spring

system comprising of suspended shaft (22). external and internal sustained bolts (24 & 25). The conveyor belt (10) speed was set from a range of 0- 10 m/rhin with the help of an electronically speed regulated roller drive (11). The motor (3)

20    of crank (2) system was switched on before starting the conveyor roller drive (11) located at the discharging end of the device. The shoots were continuously fed into the hopper/bin (14) at the charging end ensuring that the thickness of feed

was maintained at 350 mm at the top dead centre of the crank (2).  The tea

shoots coming out at discharging end was spread in withering trough for a period

25    of 4 Y, to 5 Y, hours w~h an intermittent switching off of fan for Y, hours after every 2 hours of operation. At the end, determined by physical feeling of the shoots and also by the conventional smell/ 'nose'of the shoots, after 5 hours in

the trough the shoots were declared right for processing.  The withered shoots

were weighed and the moisture content of shoots determined.  The shoots were

30    processed by commercially known Rotavane - CTC process, fermented and finally dried in a fluid bed dryer to get the end product, CTC -tea.

15


Example-1

The device of the present invention as shown in figures 1 and 2, was preset with a crank (2) cycles of 18 per minute, the six pressure pads (21) starting from feed end to discharge end were set at differential gradient of 250 - 225 - 200 - 175 - 150- 125 mm and the electronic roller (11) speed set at 2 meters per minute to ensure approximately 3 impressions at each pressure pad (21). Thousand kilograms of tea shoots comprising of 55 percent two and a bud were fed into the bin (14) at the feeding end ensuring 350 mm thickness at the maximum dead

10    centre of the crank (2). The crank was sella 350 mm at top dead centre and 250 mm at bottom dead centre. The entire 1000 kg of shoots could be preconditioned for wither in 20 min and were lifted manually from the floor at the discharging end of the device and spread in an open cement trough fitted with air circulating fan

used in the factory for withering the tea shoots.  At the end of 5 hours, when the

15    shoots had developed the 'nose'/smelland also had the physical feel of wither, the shoots were weighed and processed further by Rotavane - CTC, fermentation and dried to get, CTC -tea. A small sample of withered shoots was taken for determining the moisture content and results are tabulated in Table 1

below.

20

Table 1

Quality of tea leaves

    Shoots fed    Time  taken  for    Weight    Percent    Taster's    opinion   
        preconditioning    after    moisture in    on Tea infusion   
            wither    leaf               
                               
                           
                               
Example 1    1000 kg    20 min    750 kg    71%    Brisk    having   
                    useful strength   

Example-2

The device of the present invention as shown in figures 1 and 2, was preset with a crank (2) cycles of 18 per minute, the six pressure pads (21) starting from feed end to discharge end were set at differential gradient of 250 - 250 - 200 - 200 - 125- 125 mm with the help of outer and inner nuts (24 & 25) on suspended shafts (22) and the electronic roller (11) speed set at 2 meter per minute to ensure approximately 3 impressions at each pressure pad (21). Thousand kilograms of tea shoots comprising of 55 percent two and a bud were fed into the

10    hopper/bin (14) at the feeding end ensuring 350 mm thickness at the maximum dead centre of the crank (2). The crank was set to 350 mm at top dead centre and 250 mm at bottom dead centre. The entire 1000 kg of shoots could be preconditioned for wither in 20 min and were lifted manually from the floor at the discharging end of the device and spread in an open cement trough fitted with air

15    circulating fan used in the factory for withering the tea shoots. At the end of 5 hours, when the shoots had developed the 'nose'/smelland also had the physical feel of wither, the shoots were weighed and processed further by Rotavane - CTC, fermentation and dried to get, CTC - tea. A small sample of withered

shoots was taken for determining the moisture content and results are tabulated 20 in Table 2 below.

Table 2 Quality of tea leaves

Shoots fed Time taken for Weight Percent Taster's opinion preconditioning after moisture in on Tea infusion
wither    leaf

Example 2   1000 kg    20 min    714 kg    69%    Cups  are  bright

coloring    with

strength    and

moderate

briskness

The main advantages of the mobile tea shoot pre-conditioning device of the

present invention for withering during black lea manufacture are:

1.    The device overcomes the limitation of prior art in that the amount of tea leaf/shoots that can be precondttioned for withering can be increased to suit the requirement in a normal black tea processing factory.

2.    With improvisation in one or all of the following process parameters namely the thickness of feed, the speed of conveyer belt and the frequency of th~ movement of the crank drive the out put of the device can be varied over a wide range.

10    3. The thickness of feeding the shoots may be controlled and made uniform with provision of hopper.

4.    A suitable device can handle different types of shoots of different germplasm like pure chinary, pure assamica or hybrid used by the tea factory.

15    5. Integrating the device of the present invention into an existing tea manufacturing set up through a suitable conveyor system and air circulation system, withering of tea shoots may be made continuous which at the end of desired period and the treated shoots be synchronized with

other processing machines like rolling task! Rotavane and CTC, fermentor

20    and drying systems to give the end product 'BlackTea'.

6.    Reduces factory space needed for withering of shoots.

7.    Will result in substantial saving of energy needed for withering of shoots.

B.    Better utilization of factory infrastructure and manpower is possible.

9.    Reduction  in  withering  time  will  help  the  factories  process  more

25    leaf/shoots provided at the field level due to better yielding clones, rush period crop due to enhanced rate of growth of shoots or unforeseen conditions like labour absenteeism, due to holidays, strike etc.

10.    Huge gardens having several divisions/sections from which the shoots are collected but centrally manufacture the black tea may establish the device

30    at suitable collection points, treat the shoots, collect in suitable ventilated trolley mounted system and shift to the factory for loading on to troughs/

18

continuous withering systems and process the shoots even faster than the normal processing time. The treatment at leaf collection centers will result in gaining the time lost due to storage of shoots at the collection centers before transportation to the factories.

11.    Due to the present invention, the shoots coming as suggested in 11 can be discharged/ unloaded on to a continuous withering system and other

processing system. Thus, the factory can process more crop with the existing processing facility.

12. The present invention gives the choice of putting the device on wheels to I 0 make it mobile or grouted to the ground.
13.    Further increase in throughput is achieved by suitably stacking or arranging the conveyor and pressure pad systems adjacent to one another and accordingly increasing the horse power of the motor crank assembly.

We claim:

1.    A mobile tea shoot preconditioning device for withering during black tea manufacture, which comprises a super structure consisting of three modules: (i) a horizontal rigid base plate having a variable crankshaft mechanism, (ii) a plurality of pressure pads unevenly mounted in a variable gradient and (iii) an anti-pressure plate consisting of a rigid top supporting a variable speed endless conveyor belt capable of holding tea

shoots; the said modules being mounted in combination on to the said

10    super structure in such a manner that the said base plate mounted crank shaft mechanism is capable of providing relative vertical movement between the said plurality of pressure pads unevenly mounted in a gradient and the tea shoot carrying endless conveyor belt mounted on the said anti-pressure plate.

IS

2.    A device as claimed in claim 1, wherein the variable crankshaft mechanism is capable of providing 24 to 36 vertical movements per minute; and is provided with a reduction gear-box or belt drive or chain

drive or hydraulic system; and an adjustable crank plate with slots to vary

20    the crank centers.

3.    A device as claimed in claim 1-2, wherein the variable speed endless conveyor belt is driven by a drum type motor with variable speed of up to 40 rpm or by reduction gear box drive with mechanized speed variator or

25    by steep pulley arrangement.

4.    A device as claimed in claim 1-3, wherein the height of the plurality of pressure pads unevenly mounted in a variable gradient in relation to the

conveyor belt is adjusted singly or in groups to impart pressure in a range

30    between 50 to150 gm/cm2on to the tea shoots being carried on the said conveyor belt.

20
 

5.    A device as claimed in claim 1-4, wherein the rigid top supporting a variable speed endless conveyor belt is provided at the tea shoot charging end with a detachable feed regulator.

6.    A device as claimed in claim 1-11, wherein the super structure is provided with one or more pressure pad modules coupled with anti-pressure plate module in multi-tier configuration.

7.    A device as claimed in claim 1-12, wherein the device comprises a super

10    structure having in combination a base plate (1,7,8,9,19,27) provided with a variable crank mechanism (2,3,4,5,6, 17,28) connected to an anti-pressure plate mechanism (10,11,12,13,14,15,16,18,26,29) consisting of a rigid top (13) supporting an endless conveyor assembly (10, 11, 12, 16)

and a plurality of pressure pads unevenly mounted in a variable gradient

15    (15,20,21,22,23,24, 25,26), wherein a crank drive (2) and electric motor (3) are mounted through supporting plate (9) on to the rigid base plate (1), the said crank drive (2} is connected to an electric motor (3) through coupling attachment (4), drive shaft (5) mounted on reduction gear box (6) fixed on horizontal cross members (7} and intemnediate up-right members (8) fixed

20    on the said rigid base plate (1); the said anti-pressure plate mechanism (10,11,12, 13,14,15, 16,18,26,29) consists of endless conveyor belt (10) on adjustable electronically speed regulated drum type motor drive (11) at discharging end and an idle conveyor roller (12) at charging end

supported by rigid top (13) at the bottom, a detachable hopper/bin (14)

25    with side guard provided with up-rights (15) of varying lengths covering the said entire conveyor belt from both sides and whole assembly is fixed on a movable horizontal frame work (16), the said movable horizontal frame

work (16) is attached to the said crank system (2 and 28) through a vertical rod (17) and attached through flat or coil type carrying springs (18)

30    to the upper member (19) of the said rigid base plate (1); the plurality of pressure pads unevenly mounted in a variable gradient

21
 

(15,20,21,22,23,24,25,26) is provided with a pressure pad carrying structure (20) consisting of height adjustable pressure pads (21) tightened on sustained shafts (22) with pressure adjusting springs (23) mounted for free movement of said shafts (22) and sustained internal (24) and external (25) bolts is welded or bolted through up-rights (26) on the said upper members (19) of the said base plate (1) provided with wheels (27) for mobility.

8.    A device as claimed in claim 7, wherein the rigid top (13) is attached to the

10    movable horizontal frame work (16) by up-rights (29).

9.    A device as claimed in claim 7-8, wherein the height of pressure pad (21) is adjusted independently or in combination by means of internal (24) and/or external (25) sustained bolts.

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