GB2157409A

GB2157409A - Withering tea leaves

Info

Publication number: GB2157409A
Application number: GB08409521A
Authority: GB
Inventors: Torun Chandra Boruah
Original assignee: TEA RESEARCH ASS
Current assignee: TEA RESEARCH ASS
Priority date: 1984-04-12
Filing date: 1984-04-12
Publication date: 1985-10-23
Also published as: KE3824A; BR8501700A; MW985A1; SG63388G; GB2157409B

Abstract

A device for withering tea leaves continuously comprises a chamber (1) having an inlet end and an opposite end, said chamber being provided with guide rails (2) for accommodating a plurality of trays (3) in two (or more pairs of) runs. The trays are disposed in an inclined manner. A duct (19) is provided for forcing hot air into said chamber, and there are also means (7, 8) for moving said trays through said chamber, means (14) for carrying said trays at the end of a run to the next lower run, means (15, 16) for returning trays through a lower run, and means (18) for lifting said trays after discharging the withered tea leaves to the top run where green tea leaves are fed. <IMAGE>

Description

SPECIFICATION A device for withering tea leaves in a continuous and controlled manner The present invention relates to a device for withering tea leaves in a continuous and controlled manner.

There are various devices for withering of tea leaves in a controlled manner. In one type, leaf is spread thinly on tats inside a room into which a blast of hot air is forced. In another type, leaf is spread at a thickness upto 25 cm on a wire mesh or some fabric mesh over the top of a horizontal duct into which a blast of hot air is forced.

In all the aforesaid devices known in the art, uniformity in withering tea leaves is not achieved despite the fact that the rate of withering may be controlled by controlling the temperature of the hot air.

Another disadvantage of the known devices is that these essentially work in batches and occupy a considerably large space.

The primary object of the present invention is to wither tea leaves not only in a controlled manner bust also in continuous manner.

Another object of the present invention is to obtain a good uniformity in withering of tea leaves.

A further object of the present invention is saving of horizontal (floor) space by utilising a larger vertical space.

The present invention relates to a device having arrangements for continuous feeding and continuous discharge and since the tea leaves are thinly spread on trays a good uniformity in withering is obtained and with other arrangements in the device, the tea leaves are withered in a controlled manner and also in a continuous manner. A very important advantage of the device according to the present invention is that the trays for the tea leaves are disposed in an inclined position utilising a larger vertical space for saving horizontal (floor) space so that a larger vertical space is filled with tea leaves even with the thin spread on the trays for getting a high capacity while occupying a small area.

According to the present invention there is provided a device for withering tea leaves in a continuous and controlled manner comprising 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, said trays being disposed in an inclined manner, duct means for forcing hot air into said chamber, means for moving said trays through said chamber, means for returning trays through a lower run and means for lifting said tray after discharging the withered tea leaves to the top run where green tea leaves are fed.

The trays for the tea leaves are fitted with wheels that is upper wheels and lower wheels.

However, the track for the lower wheels is wider than the track for the upper wheels.

For the purpose of lifting the trays after dicharging the withered tea leaves, there is provided a pair of chain-and-sprocket mechanisms with hooks at regular intervals. Similarly a pair of chain-and-sprocket mechanisms with hooks are provided for carrying the trays to the lower run from an upper run. Means are provided at the end of the last run below the inlet end of the chamber for guiding and turning the trays upside down and for rolling down the trays after turning upside down.

The present invention will now be described by way of example with reference to the accompanying drawings.

Figure 1 shows the elevation of the device with the front cover removed; Figure 2 shows a tray used in the device.

The chamber (1) is provided inside with a set of guide rails (2) for two (or more pairs of) runs of trays (3) fitted with wheels (4) the trays being disposed in an inclined position, the wheels (4) of the trays resting over the guide rails. The track (5) of the lower wheels being wider than the track (6) of the upper wheels. A pair of spring loaded mechanisms (7) driven by a pair of cams (8) are provided near the inlet of the chamber (1) to push the trays through the chamber in the top run.A pair of chain-and-sprocket-mechanisms (9), the chains being fitted with hooks (10) at regular intervals, and guide rails (11) extending from the top run inside the chamber (1), are provided near the inlet of the chamber (1) to lift the trays (3), to the chamber inlet, the hooks (10) being fitted at such intervals that when the trays are moved up, the trailing end of a tray is just above the leading end of the next tray. A mechanical spreader (12) is fitted above the guide rails (11) to charge the trays with green tea leaves. A pair of chain-andsprocket-mechanisms (13), the chain being fitted with hooks (14), are provided at the opposite end of the chamber to carry the trays from the top run to the next lower run.A pair of spring loaded mechanisms (15) driven by a pair of cams (16) are provided at this end to push the trays during their return journey through the chamber along the 2nd run. The total number of similar trays runs with similar mechanisms may be 2, 4, 6 or any even number. At the end of the last run, below the inlet to the chamber, a pair of circular guides (17) are provided to guide the trays and to turn them upside down after coming out from the chamber. Another set of guide rails (18) are provided here for the trays to roll down after turning upside down. An air duct (19) is connected to the chamber at the bottom for forcing in hot air. The air duct could be connected at the top or on a side also.

Working of the device Green ten leaves are fed to the mechanical spreader (12) which charges the trays (3) over the guide rails (11) while being carried up by the chain-and-sprocket-mechanisms (9) with the help of hooks (10). Each tray (3) charged with green tea leaves is carried upto the inlet of the chamber (1) when the spring loaded mechanisms (7) take over and push the tray (3) and while doing so push all the trays (3) ahead further into the chamber (1). Simultaneously a tray (3) is pushed out of the chamber (1) at the other end or opposite end and is received by the chain-and-sprocket mechanisms (13) with the help of hooks (14). The chain and sprocket mechanisms carry the tray (3) down to the next lower run for a return journey of the tray through the chamber (1).

The spring loaded mechanisms (15) then push the tray and along with it all the trays ahead into the chamber. Simultaneously a tray is pushed out of the chamber (1) at the former end, below the inlet position, and the tray is guided to swing down the circular guides (17) and to turn upside down, and hence to discharge the leaves on it, and then to roll down the guide rails (18), after which the tray gets engaged to the hooks (10) of the chains of the mechanisms (9) which lift up and carry the tray to the inlet position again.

The green tea leaves during their passage through the chambers in either direction gets withered by a blast of hot air supplied to the chamber (1) through the air duct (19). The degree of withering can be controlled by controlling the temperature, and hence the humidity of the blast of air, by varying the runthrough time of the trays through the chamber with the help of a common variable speed drive for the mechanisms (7), (9) and (15), or by varying the thickness of spread of the green leaf through some adjustments of the spreader (1 2).

Claims

1. A device for withering tea leaves in a continuous and controlled manner comprising a chamber having an inlet end and an opposite end, said chamber being provided with guide rails for accomodating a plurality of trays in two (or more pairs of) runs, said trays being disposed in an inclined manner, a duct for forcing hot air into said chamber, means for moving said trays through said chamber, 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.

2. A device as claimed in claim 1 wherein said trays are fitted with upper wheels and lower wheels.

3. A device as claimed in claim 2 wherein track for said lower wheels is wider than the track for said upper wheels.

4. A device as claimed in any of the preceding claims wherein said means for lifting said trays after discharging the withered tea leaves are a pair of chain- and-sprocket mechanisms with hooks.

5. A device as claimed in claim 4 wherein said hooks are fitted at intervals such that the trailing end of a tray is above the leading end of the next tray.

6. A device as claimed in claims 1 to 5 wherein means for moving said trays through the chamber are a pair of spring loaded pushing mechanisms driven by a pair of cams.

7. A device as claimed in claims 1 to 3 wherein means for carrying said trays to the lower run from the upper run are a pair of chain-and-sprocket mechanisms with hooks.

8. A device as claimed in claims 1 to 7 wherein means for returning said trays through the lower run are a pair of spring loaded pushing mechanisms driven by a pair of cams.

9. A device as claimed in any of the preceding claims wherein means are provided below the inlet end of said chamber for guiding and turning said trays upside down and for rolling down said trays thereafter.

10. A device as claimed in claim 1 to 9 wherein means for supplying conditioned air is an air duct connected to the chamber at the bottom top or side.

11. A device for withering tea leaves in a continuous and controlled manner substantially as herein described and with reference to the accompanying drawings.