Withering Troughs:
Are generally installed in the first floor of the factory. Green leaf is spread over a wire mesh (No.4/16 16gauge) which is fitted on plenum chamber. Height of the plenum chamber is 0.6-.76 m (2-2.5 feet) and leaf is loaded over the mesh to.20-.23 m (8-9″) height or 8-9 kg/sq. m. (2.5-3 kg/sq. ft.) of the withering trough. Size of the withering trough is 30.5 m (100′) long 1.8 m (6′) wider or 22.9 m (75′) long and 1.8 m (6′) wide. Better withering can be achieved with smaller trough 22.9 X 1.8 m (75′ x 6′). The trough should be fitted with a suitable fan to deliver the required quantity of air as per the size of the trough. To achieve proper withering the fan has to deliver 45 CFM air for every one square foot of trough area. For artificial withering hot air from the drier room is bulked with outside air and used. Fans are arranged in such a way that they can draw hot air from the drier and cool air from the atmosphere
Green Leaf Sifter:
Is designed to remove extraneous matter such as stones, metal pieces etc to avoid damage to CTC rollers. The green leaf sifter consists of a reciprocating tray powered with an electric motor. The reciprocating tray is fitted with a mesh through which leaves are passed and unwanted materials removed. Powerful magnets are fitted in the sifter which removes iron/steel particles from the green leaf.
Green Leaf Shredder:
Is a pre-conditioning machine. The machine shreds the leaves into small pieces before sending it to the rotorvane. Besides, the green leaf shredder helps to increase the rotorvane capacity and in efficient mixing of RC material to the withered leaf especially in the CTC type of processing. The machine consists of a cylinder in which the main shaft having knives (blades) rotate at a speed of 2500 RPM.
Orthodox Roller:
A conventional roller for orthodox rolling consists of three parts- the table, the hood and the pressure cap. Rotation of the machine is achieved through three crankshafts attached to the table. The level gear mechanism transmits power to one of the crankshafts at a time, while the other two rotate freely on their bearings and play an auxiliary role. The pressure cap applies pressure to the leaf mass during rolling, imparting the proper twisting and brushing action. It is the pressure applied during orthodox rolling that causes the extraction of sap and imparts twist to the leaf. In some kinds of rolling tables, both vertical and lateral pressures may be applied. Vertical pressure is applied with the help of pressure caps, whereas lateral pressure is applied by a cone fitted in the middle of the table. This cone also causes greater circulation of leaf than that provided by battens alone
Rotorvane:
consists of a cylindrical drum of a diameter of 200 cm (8″), 380 cm (15″) or 460 cm (18″), depending on the capacity. Inside the circumference of the drum, the resistors are fitted at appropriate distances. The main shaft which rotates inside the drum, has vanes at equal intervals. There is a worm arrangement in the main shaft which facilitates forward motion of the leaves into the drum. The leaves are crushed in between the vanes and resistors and discharged through the diaphragm. The RPM of rotorvane ranges from 30 to 35.
CTC-Rollers:
consist of a main shaft on which the segments are fixed by heat treatment on a mandrel form. The diameter of the roller is generally 200 cm (8″) and the latest senova rollers are of 330 cm (13″) diameter. Depending on the capacity of the rollers, their length varies from 600 (24″) to 910 cm (36″). Generally two rollers are fixed horizontally and parallel to each other and both rotate in opposite directions. The ratio of speed between the low speed and high speed rollers is 1:10 depending on the requirement of leaf or dust grade.
Fermentation Drum:
The fermenting drum is a simple cylindrical drum with conical feeding and discharge ends. The standard drum is 4.8 – 6.1 m (16-20 feet) long and has a diameter of 1.5 m (5 feet) at the cylindrical portion. The total length of the conical segment is four feet. The capacity of the drum will be 5.2 kg of rolled dhool for every square meter area of the drum.
Continuous Fermenting Machine:
helps to eliminate microbial contamination in tea. Micro organisms occur as contaminants during tea processing due to the presence of a layer of fermented juice on the processing machines and other equipments. The CFMs consist of a tray made up of conveyor racks with three to four tier systems like “quality” drier arrangements. The fermented dhools travel in a thin layer on the conveyor rack. Above or below the tray, UV lamps are fitted which are used to kill the external bacteria and triggers the activity of polyphenol oxidase, thereby hastening the biochemical reaction. Bright infusions are obtained in the continuous fermenting machine. This machine is generally used for NRC tea manufacture. In RC tea manufacture googhie sifter is used before CFM for granulation of tea.
ECP Drier:
The Endless Chain Pressure type driers consist of two or three individual tray circuits. When the leaf is fed into the feeding circuit, the spreader spreads the leaf uniformly on the tray. As soon as the leaf completes the run on top circuit, the tray carrying leaf are automatically tilted at the end of the circuit and the leaf falls on the mid circuit where direction of tray movement is opposite to that of top circuit. Thus the leaf is subjected to gradual high temperature from top to bottom circuit and drying is completed when the leaf reaches the bottom circuit. The total drying time is 20-22 minutes. The output of the drier is 200-250 kg made tea with the feeding moisture level of 55%. The inlet and exhaust temperatures may be maintained at 100°C and 55°C, respectively.
Fluid Bed Drier:
onsists of drying chamber, plenum chamber, air flow damper and dust collectors. The drying chamber is separated by a perforated grid plate through which high pressure hot air from the plenum chamber gets into the drying chamber for fluidisation. The plenum chamber is divided into four zones which have individual air control valves. These valves control the quantity of air to the individual zone and the direction of hot air entering the control dampers. At the top of the drying chamber two centrifugal exhaust fans are fitted with cyclone, one for refiring and the other for dust extraction. When the fermented dhool is fed into the drying chamber in the first zone it gets fluidised. With the help of pressurised hot air, water is removed by evaporation. The inlet and exhaust temperatures for FBD may be maintained at 250°F to 260°F and 150-160°F for achieving better quality.
Vibro Fluid Bed Drier:
works on the principle of ‘vibrating fluidized bed’. It works on pneumatic and mechanical power. The fermented teas are fed through a feed system into the drying chamber. Hot air from the heater is passed from underneath to the drying chamber through the perforated tray carrying wet teas. The tea leaf is effectively fluidised by a combination of air pressure and mechanical vibration.
Combination Drier:
Tempest drier is a combination of conventional and fluid bed drier. In the tempest drier on top of the drying chamber i.e., above the fluidisation zone there is a tray moving inside which carries the fermented leaf from the drum where surface moisture is removed by exhaust temperature. Since a certain percentage of moisture is removed from the leaf before entering into the fluidisation zone, the output of the drier is higher than conventional FBD.
Fibre Extractor:
This works on the principles of static electricity. There are 4 to 6 PVC rollers arranged in a row. The PVC rollers brushes against thick pads of felt which imparts a static electricity to developed on the PVC rollers. When tea is fed in to fibre extractor after firing, frictional force takes place between fibre and the rollers. As a result static electricity is produced. The PVC rollers act as positive charge (+) and fibre acts as a negative charge (-), thereby both attract each other and fibre is collected from the PVC rolle.
Sorter:
Is a simple machine which is used to grade the bulk tea from the fibre extractor into different grades according to their size. Generally the sorter is fitted with meshes of different size.
