TOBACCO SEPARATOR

Abstract: A tobacco separator is provided for separating light fractions (laminae) from heavy fractions (mid-rib or stem) from threshed tobacco. The separator comprises a separating chamber (10) having an upper first inlet (8) for receiving the material to be separated or classified, and a lower second inlet (9) for receiving a flow of air directed transversely of the material path from the first inlet, a plurality of channels (14-17) are disposed one above the other to receive the tobacco laden air from said inlet, a vertical air passage (20) in communica­ tion at its lower end with the lowermost of said channels; and an outlet passage (19) in communication with all said channels.

Description: TITLE: TOBACCO SEPARATOR This invention relates to a separator 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 US 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 disadvantage 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 'trasnverse' 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 t 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. A tangential separator is also known such as shown in UK Patent No. 713,693 to RoweIl. 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 tak-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 light fractions from heavy fractions, comprising a seprating chamber having an upper first inlet for receiving the material to be separated or classified, and a lower second inlet for receiving a flow of air directed transversely of the material path from the first inlet; a plurality of channels disposed one above the other to receive the tobacco laden air from said inlets, a vertical air passage in communication at its lower end with the lowermost of said channels, and an outlet passage in communication with said 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 lOB. The inlet compartment 10A has a horizontal air flow entering inlet 9 from a fan 11 through a duct 1?. 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 iOA by the drum, thus 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 14B-16B and then horizontally at 14C-16Cnd merge into a single outlet passage 19. The bottom opening 17 leads by a separate channel 17A 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. 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 at 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 a compartmented wheel 21, which is divided by vanes 21A into a series of compartments 21B. By providing three laminaeocollection 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 30" (76 cm) to 60" (152 cm) wide and the chamber 48" (132 cm) 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 11 and chamber air inlet 9. The system may use approximately 250 cubic feet per minute of air per inch of the width of the machine (2.78 cubic metres per minute per centimetre) and handles approximately 100 Ibs. (224 kg) of tobacco leaf per inch of width. The air may be separated from the clean laminae and recirculated back to the fan inlet.

Claims: CLAIMS: 1. A tobacco separator for separating light fractions from heavy fractions, comprising:a) a separating chamber (10) having an upper first inlet (8) for receiving the material to be separated or 'classified, and a lower second inlet (9) for receiving a flow of air directed transversely of the material path from the first inlet; b) a plurality of channels (14-17) disposed one above the other to receive the tobacco laden air from said inlets; c) a vertical air passage (20) in communication at its lower end with the lowermost of said channels; and d) an outlet passage (19) in communication with all said channels. r' 2. A separator as claimed in Claim 1, comprising a first compartment (10A) having said inlets and a second compartment (lOB) having an inlet side divided into a . ,. bottom opening (17) and a plurality of upper openings (14, 15, 16), said bottom opening (17) leading by one channel (17A) into the lower end of said vertical air passage (20) and said upper openings leading (14, 15, 16) to the other of said channels (14A, 14A, 14A), the latter extending upwards (14B, 15B, 15B) and then horizontally (14C, 15C, 16C) to the outlet passage, and a compartmented wheel (21) is provided at the bottom of said vertical air passage (20) for removal of tobacco stem. 3. A separator as claimed in Claim 1 or 2, wherein four said channels are provided. 4. A separator as claimed in Claim 1, 2 or 3, provided with an upwardly extending series of adjustable louvres (18) at the second inlet (9). 5. A separator as claimed in Claim 4, wherein the lowermost louvres are capable of being opened to a larger extent than the remaining louvres thereby to permit a high-velocity stream of air to pass along the bottom surface of the second compartment (lOB) to drive the tobacco stem towards the vertical air passage (20). 6. A separator as claimed in Claim 1, including a threshing drum mounted directly on said first inlet.

Inventors: HUDSON, JOHN HOLLAND, JR., VECCHIO, ANTHONY JAMES
Applicants: AMF INCORPORATED
Application year: 1984
Main classification: A24B5
IPC codes: A24B3, A24B5, B07B4, B07B11