EP0139422B1

EP0139422B1 - Tobacco separator

Info

Publication number: EP0139422B1
Application number: EP19840305927
Authority: EP
Inventors: Anthony James Vecchio; John Holland Hudson, Jr.
Original assignee: AMF Inc
Current assignee: AMF Inc
Priority date: 1983-09-13
Filing date: 1984-08-30
Publication date: 1988-05-04
Also published as: DE3470829D1; GB8324443D0; EP0139422A1; ZW14784A1; JPS6087777A; CA1218576A

Description

This invention relates to a tobacco separator for separating tobacco into light and heavy fractions more especially for classifying or separating the laminae from the mid-rib or stem from threshed tobacco.
The complete threshing process comprises successive stages of threshing and separating. A typical threshing drum is described in our U.S. Patent No. 4,077,573.
In the simplest form of known pneumatic separator, it comprises a 'tower' separator chamber having a vertical duct with an up draught. The output from the threshing drum is thrown horizontally into the duct near the bottom of the chamber, and the vertical up draught is adjusted to allow the heavy stems to descend to a take-off conveyor, and the lighter tobacco laminae to be conveyed upwards by the air flow. Such a separator is described by Rowell et al in US Patent No. 3,164,548.
The disavantage of the above mentioned 'tower' separator is that there is some conflict between the light ascending particles and heavy descending particles, which reduces the efficiency.
An alternative design of a 'transverse' separator is shown in our US Patent No. 3,593,851 in which the air flow is horizontal across a chamber. The threshed products are thrown horizontally against the air flow into the top of the chamber by a winnower. The heavy stems are thrown to the far air inlet side of the chamber where they fall onto a take-off conveyor. The light laminae are thrown a lesser distance and are drawn back into the exhaust duct.
The disadvantage of the above mentioned 'transverse' air flow separator is that there is insufficient height to ensure that all the laminae are drawn off into the exhaust duct, so that several stages of separation are required to give efficient separation.
In a variant of the 'tower' type of separator the product is introduced by a fast conveyor, but there is a tendency for clumping of the product, which lowers efficiency.
The product is normally conveyed pneumatically between the stages of threshing and separating so that the tobacco has to be separated from the air before feeding into the next stage of thresher or separator.
Another 'tower' type of separator is known from UK Patent No. 959730 to Korber. In GB-A-959730 all the channels open into a common chamber whereby the disadvantage arises that initial separation does not take place.
A tangential separator is also known such as shown in the UK Patent No. 713,693 to Rowell (GB-A-713693).
A further disadvantage of existing separators is that the winnower with its high speed blades, causes degradation of the product. Also the unloader and its compartmented wheel of a tangential separator can cause degradation of the product.
Another disadvantage is that the take-off conveyor belt wears and has tracking problems.
An object of the present invention is to overcome these disadvantages.
According to the invention there is provided a tobacco separator for separating tobacco into light and heavy fractions, comprising:

- a separating chamber having a first inlet at its upper end for receiving from a threshing drum mounted in said inlet tobacco to be so separated, and a second inlet at its lower part for introducing an air draft into the separating chamber;
- a plurality of channels disposed one above the other and extending upwards from their lower ends into which the tobacco laden air draught enters atthe tower part of the separating chamber;
- an outlet passage in communication with all upper ends of said channels for receiving air with lighter tobacco therein; and
a vertical air passage arranged in communication with at least the lowermost of said channels for receiving an air draught laden with both light and heavy fractions of tobacco, with a communication at its upper end with said outlet passage, forming thereby the upper end of the at least one channel communicating with said outlet passage, and with an outlet at its lower end for removing the heavier tobacco components; characterised in that:
- said vertical air passage communicates solely and at its lower end with the lowermost of said channels and has its outlet for removing the heavier tobacco components controlled by a moving device;
. - said outlet passage is a horizontal passage and all said channels are connected independently of each other with said horizontal outlet passage, the lowermost channel by means of the vertical air passage;
- and said air draught inlet of the separating chamber is provided with a series of independently adjustable louvres located between said inlet and the channels.

The invention will now be described by way of example with reference to the accompanying drawing which shows a schematic sectional view of the separator.
In the present invention there is provided a separating chamber 10 having an inlet compartment 10A and an outlet compartment 10B. The - inlet compartment 10A has a horizontal air flow entering inlet 9 from a fan 11 through a duct 12. A threshing drum 13 is mounted directly on top of the chamber 10 so that tobacco is thrown directly through an upper inlet 8 into the compartment 10A by the drum, this eliminating the need for a separate winnower and unloader.
The inlet compartment 10A is higher compared with known apparatus so that four side openings 14-17 can be accommodated to remove the tobacco laden air. Air enters the chamber on the opposite side from the passages through a . number of adjustable louvres 18 extending from the top to the bottom of the compartment 10A. The three uppermost openings 14-16 lead to channels 14A-16A which extend upwards at 14B16B and then horizontally at 14C-16C and merge into a single outlet passage 19. The bottom opening 17 leads by a separate channel 17C to the lower end of a vertical air passage 20, the upper end of which also leads to the outlet passage 19.
The air flow distribution is adjusted by the louvres so that the air is at a progressively higher speed towards the bottom of the compartment 10A, so that the top three openings 14-17, collect light laminae, and the opening 17 collects heavy stem or stem with laminae attached.
The vertical air passage 20 provides for a further removal of clean laminae i.e., without stem, which may be entrained by the stem. Lightweight particles from the passage 20 can pass via 17C to the passage 19.
The stem is conveyed from the compartment 10A to the vertical air passage 20 pneumatically, instead of by a conveyor band as in known apparatus.
The louvres nearest to the bottom of the compartment 10A is adjusted to give a high air velocity at the bottom surface (about double that of the velocity of the upper end of the compartment 10A), so that heavy stems, which tend to drop onto the surface are swept along into the bottom opening 17 and into the vertical air passages. The stem falls to the bottom of the vertical air passage and is removed by the compartmented wheel 21, which is divided by vanes 21A into a series of compartments 21 B.
By providing three laminae collection side passages 14-16 a greater opportunity is provided for clean laminae to be separated and a higher separating efficiency to be achieved.
The threshing drum 13 and separating chamber 10 can typically be made from 76 cm (30") to 152 cm (60") wide and the chamber 132 cm (48") high. The air must be uniformly distributed across the width of the chamber so air guides may be provided in the duct 12 between the fan 12 and chamber air inlet 9.
The system may use approximately 2.78 cubic metres per minute per centimetre (250 cubic feet per minute of air per inch) of the width of the machine and handles approximately 88 kg of tobacco leaf per centimetre of width. The air may be separted from the clean laminae and recirculated back to the fan inlet.

Claims

1. A tobaco separator for separating tobacco into light and heavy fractions, comprising:

- a separating chamber (10A, 10B) having a first inlet (8) at its upper end for receiving from a threshing drum (13) mounted in said inlet tobacco to be so separated, and a second inlet (12) at its lower part for introducing an air draft into the separating chamber;

- a plurality of channels (14-17) disposed one above the other and extending upwards from their lower ends into which the tobacco laden air draught enters at the lower part of the separating chamber;

- an outlet passage (19) in communication with all upper ends of said channels for receiving air with lighter tobacco therein; and

- a vertical air passage (20) arranged in communication with at least the lowermost (17) of said channels for receiving an air draught laden with both light and heavy fractions of tobacco, with a communication at its upper end with said outlet passage (19), forming thereby the upper end of the at least one channel communicating with said outlet passage (19), and with an outlet at its lower end for removing the heavier tobacco components; characterised in that:

- said vertical air passage (20) communicates solely and at its lower end with the lowermost (17) of said channels and has its outlet for removing the heavier tobacco components controlled by a moving device (21);

- said outlet passage (19) is a horizontal passage and all said channels are connected independently of each other with said horizontal outlet passage, the lowermost channel (17) by means of the vertical air passage (20);

- and said air draught inlet (12) of the separating chamber is provided with a series of independently adjustable louvres (18) located between said inlet (12) and the channels (14-17).

2. A separator as claimed in Claim 1, characterised in that the lowermost louvres are capable of being opened to a larger extent that the remaining louvres thereby to permit a high-velocity stream of air to pass along the bottom surface of the separating chamber to drive the tobacco stem towards the vertical air passage (20).