US3785765A - Rotary tobacco dryer - Google Patents

Rotary tobacco dryer Download PDF

Info

Publication number
US3785765A
US3785765A US00227693A US3785765DA US3785765A US 3785765 A US3785765 A US 3785765A US 00227693 A US00227693 A US 00227693A US 3785765D A US3785765D A US 3785765DA US 3785765 A US3785765 A US 3785765A
Authority
US
United States
Prior art keywords
drum
tobacco
dryer
air
dryer according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00227693A
Other languages
English (en)
Inventor
L Rowell
J Cartmell
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Tobacco Canada Ltd
Original Assignee
Imasco Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imasco Ltd filed Critical Imasco Ltd
Application granted granted Critical
Publication of US3785765A publication Critical patent/US3785765A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
    • A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
    • A24B3/00—Preparing tobacco in the factory
    • A24B3/04—Humidifying or drying tobacco bunches or cut tobacco

Definitions

  • a tobacco dryer which comprises a rotating substantially cylindrical drum in which the tobacco is dried.
  • the drum has a first end and a second end and the tobacco which is to be dried enters the first end of the drum and leaves at the second end of the drum.
  • Process air which has a low absolute humidity is introduced into the drum at the second end and flows through the drum in the opposite direction to the flow of tobacco, so as to pick up and remove from the drum, moisture released from the tobacco.
  • a gas fired burner located within the dryer housing produces heating air. This heating air is forced over the exterior surfaces of the rotating drum at a velocity between 500 feet per minute and 3,500 feet per minute so as to increase the heat conductance through the rotating drum.
  • the dryer is also provided with a controlled water spray which is introduced into the second end of the rotating drum and thereby controls the moisture content of the tobacco leaving the dryer.
  • This novel drying device also exhibits a dynamic operating range which is wider than many known devices by increasing the quantity of heat transferred through the dryer drum surface by moving the heating air over the drums exterior surface at high relative velocities.
  • the dryer of the present invention further increases the quantity of heat transferred to the tobacco by forcing heating air at high velocities through hollow paddles which are arranged on the interior of the drying drum.
  • tobacco dryers be capable of operating over a wide range of loads. For example, one week a dryer might be required which is capable of drying tobacco-at the rate of 10,000 pounds per hour, and that same dryer the next week, might be required to dry tobacco at the rate of 2,500 pounds per hour, representing a loading change on the dryer of approximately 400 percent.
  • This type of load change can be thought of as a long term load change.
  • a tobacco dryer capable of handling this type of long term load change must necessarily have a wide dynamic range of efficient operation. r
  • Steam drying units are one type of known device for drying tobacco.
  • a steam dryer consists generally of a long rotating jacketed steam .heated tubular shaped drum through which is passed the tobacco to be dried. Steam pipes are arranged longitudinally within the steam heated tubular drum to form paddles. Steam is fed through rotary joints and radially extending steam pipes to the steam heated drum and to the pipes making up the paddles, and in this manner head energy is transferred via the pipes and drum walls to the tobacco tumbling within the drum.
  • the quantity of heat transferred to the tobacco is directly dependent on the surface temperature of the steam system which, of course, is dependent on the temperature of the steam circulating within the system. If the long term load on the dryer changes, the amount of heat energy released by the steam must vary accordingly, to compensate for this load change.
  • the steam drying system requires a boiler room and pipes interconnecting the boiler room with the drying unit.
  • the boiler room is costly and less efficient compared with the present inventionwhich generates all of the tobacco drying heat within the drying unit itself.
  • the tobacco dryer of the present invention has a rotating drum which is free of steam pipes, rotating joints and radially oriented steam pipes. These obstacles tend to afford places within the dryer where tobacco can hang up, producing gum and overvdrying the tobacco.
  • the present invention utilizes the fact that the quantity of heat transferred through a surface is dependent on the velocity of the heated air passing that surface in addition to the temperature of that air. For example, under similar loading conditions, air at a temperature of 455 F moving at a velocity of 3,000 feet per minute past a surface, transfers the same quantity of heat through that surface as air at a temperature over 800 F travelling at a velocity of 400 feet per minute over the surface. As a result, a tobacco dryer in accordance with the present invention yields an increased dynamic operating range without the necessity of raising the air temperature surrounding the rotating drum into excessive temperature ranges.
  • a dryer in accordance with the present invention is provided with a constant evaporating load. This is accomplished by adding a water spraying system which injects a fine water spray into the tobacco exit end of thedrying drum, thereby providing a variable evaporating load. The sum of water evaporated from the tobacco and from the fine water spray remains substantially constant.
  • a further advantage of the water spray technique according to the present invention shows itself in minimizing or eliminating over drying of the tobacco at the beginning and end of the drying operation.
  • the water spray acts as a dummy evaporating load.
  • a tobacco dryer comprising a rotating substantially cylindrical drum in which the tobacco is dried; said drum having a first end and a second end; means for introducing tobacco at said first end and means for removing tobacco at said second end; means for introducing process air into said drum at said second end and extracting said process air from said drum at said first end so that said process air travels in a direction within said drum opposite to that of said tobacco; heating means for maintaining the temperature of heating air; and means for circulating said heating air at velocity between 500 feet per minute and 3,500 feet per minute over the outer surface of said drum to thereby achieve high conductance through said drum.
  • FIG. 1 is a schematic sectional side view of one embodiment of a tobacco dryer according to the present invention
  • FIG. 2 is a schematic sectional end view of the embodiment shown in FIG. 1 taken along 22 of FIG. 1;
  • FIG. 3 is a schematic sectional end view of the embodiment shown in FIG. 1 taken along 3--3 of FIG. 1.
  • a tobacco drying drum 40 situated within an insulated housing generally indicated at 41 is mounted for rotation on two sets of trunnion wheels 42 and 44 via trunnion rings 46 and 48.
  • An electric motor (not shown) is arranged to drive the drum at a rotational speed'of approximately 10 R.P.M.
  • the tobacco 50 which is to be dried, is fed by any conventional conveyor 51 into the tobacco input hopper 52 so that it falls on the screw type conveyor 54 which feeds the tobacco into the drying drum 40.
  • the drum 40 is slightly tilted upwardly at its tobacco input hopper end so that the tobacco entering at that end will eventually move along the drum and exit at the tobacco output hopper end generally indicated at 56.
  • a fan 58 provides process air pressure at the tobacco hopper output end 56. The process air enters the drying drum 40 at its exit end and travels within the drum in a direction as indicated by arrows 60 opposite the direction of travel of the tobacco being dried.
  • the process air is extracted via the extractor pump 62 and is exhausted to the atmosphere via exhaust pipe 64.
  • a rotary air outlet screen 68 is situated in the tobacco input hopper 52 to remove small particles of tobacco which may be suspended in the process air.
  • Air dampers 70 and 72 located in the input and output pipes respectively of the process air system control the quantity of process air flowing in the drying drum.
  • the process air entering the tobacco output hopper 56 can optionally be slightly heated to reduce the tendency of condensation on metal parts. However, the degree of heating which the process air receives is only slight and does not upset the loading of the dryer.
  • the dried tobacco leaving the drying drum enters the tobacco output hopper 56 and is fed via gravity into the metering tube 74.
  • the tobacco upon leaving the metering tube 74 is removed from the dryer assembly via a conveyor 76 which can be of any conventional design. It is important that the speed at which the conveyor 76 removes the dried tobacco be controlled so that the metering tube 74 does not become empty of tobacco.
  • the process air fan 58 provides a positive pressure in the tobacco exit hopper and the tobacco filling the metering tube 74 provides a seal which does not allow the process air to exit via the metering tube. Seals 43 associated with the trunnion rings prevent the escape of process air to the exterior of the drying unit.
  • a moisture content sensing head 78 Situated on the side of the metering tube 74 is a moisture content sensing head 78 which can be of any conventional design which provides a continuous output signal proportional to the moisture content of the tobacco passing through the metering tube.
  • the output signal of the moisture content sensing head is fed to a moisture content controller 80.
  • the controller 80 ad justs a servo operated water valve 82 so as to control the quantity of water being injected into the output end of the drying drum-40.
  • the water spray nozzle 84 is of a conventional type which provides a fine spray.
  • the sensing head 78 When the sensing head 78 senses, for example, a decrease in the moisture content of the tobacco passing through the metering tube 74, a signal is received at the controller 80. The controller 80 then opens the servo.
  • the moisture content of the dried exiting tobacco can be maintained to within very close tolerances. Since the moisture content of the exiting tobacco is controlled by a water spray, changes in its moisture content may be carried out without changing the temperature of the heating air, provided the latter is within the controllable range. As a result, the moisture content of the exiting tobacco can be maintained at a predetermined desired level by variations taking only a few seconds.
  • the heat for drying thev tobacco is supplied by a burner unit 86 mounted in the housing 41.
  • the burner can be of any heat energy producing source, but a gas or oil fired burner has been found to be most efficient.
  • the burner 86 heats up the air in the outer section of the insulated housing generally indicated at 88.
  • the heated air in region 88 of the dryer assembly is pumped by fan 90 into a pressurized annular plenum 91 which surrounds the drying drum in its centre.
  • a series of hollow triangularly shaped paddles 98 seen in cross section in FIG. 2, are arranged longitudinally along the interior of the drying drum 40.
  • FIG. 2 shows only about four paddles for simplicity, but it can be appreciated that any number of paddles could be employed.
  • Each paddle 98 has a port 100 which communicates the interior of the paddles with the outside of the dryer drum 40 in the region of the plenum 91.
  • the ends of the paddles 98 also have ports 102 and 104 (FIG. 1), which communicate the hollow interior of the paddles with the region 88 of the dryer assembly.
  • Mounted externally of the dryer drum 40 is a long stationary cylindri cal shell 96, which, with the exterior wall of the rotating dryer drum, forms a narrow annular region 94.
  • the extremities of the shell 96 are arranged to communicate with the region 88 of the dryer assembly in the region of ports 102 and 104 in the paddles 98.
  • a large ringlike port 106 in the shell 96 allows for communication between the plenum 91 and the interior of the annular region 94.
  • the hot air in the plenum is forced through port 106 by the fan 90.
  • Part of the hot drying air travels at a high velocity in a longitudinal direction relative to the exterior wall of the dryer drum 40 and exits into the region 88 in the region of the ports 102 and 104.
  • the remaining part of the hot drying air enters ports 100 and travels longitudinally along the interior of the paddles 98 to exit back into region 88 of the dryer assembly via ports 102 and 104.
  • the circulation of the drying air is generally indicated by the arrows 92 in FIG. 1.
  • the cross sectional area of the annular region 94, the cross sectional area of the hollow triangular paddles 98 and the design of the fan 90, are such that the heating air travelling in the annular region 94 and the hollow paddles 98 is maintained at a high velocity. This arrangement tends to transfer a maximum amount of heat energy into the interior of the drum 40. In addition to the increased heat transfer due to the high velocity of the heating air passing over the drum and interior paddle surfaces, the present invention further increases the quantity of heat transferred by increasing the surface area of the heated surface by virtue of the triangularly shaped hollow paddles.
  • a portion of the air re-entering the region 88 of the dryer assembly is reheated and recirculated through the annular region 94 and the paddles 98, while some of the air re-entering region 88 is exhausted through the chimney 108.
  • a heat exchanger (not shown) can be inserted inthe region 88 to slightly heat the processing air.
  • FIG. 3 is a sectional end view of the dryer assembly taken in the region of the tobacco exit 56 and shows the process air fan 58, the metering tube 74, the moisture content sensing heat 78, the conveyor 76, the water spray nozzle 84 and an access door 110.
  • the water system may be connected to the door with a flexible line (not shown) to allow the door to swing open.
  • the heat transferred into the tobacco via the surface of the rotating drum and the paddles drives the water moisture out of the tobacco.
  • the process air entering the drum at the tobacco exit hopper end is relatively free'of moisture, but since it is moving in a direction opposite to that of the tobacco the process air quickly picks up the moisture liberated from the tobacco and carries it away. Because the tobacco is moving through the dryer in one direction and the process air is moving through the dryer in the opposite direction there exits within the dryer drum a region, situated at the exit end of the drum, where the tobacco is in its driest state. It is in this region that the water spray is injected for controlling the moisture content of the tobacco. In this manner, the moisture content of the tobacco may be controlled without seriously affecting the evaporation loading conditions of the dryer.
  • vanes are arranged on the rotating drum to cause the heating air travelling in the annular region 94 to follow a helical path.
  • a tobacco dryer comprising a rotating substantially cylindrical drum in which the tobacco is dried; said drum having a first end and a second end; means for introducing tobacco at said first end and means for removing tobacco at said second end; means for introducing process air into said drum at said second end and extracting said process air from said drum at said first end so that said process air travels in a direction within said drum opposite to that of said tobacco to pick up and remove from the drum, moisture released from the tobacco; heating means for maintaining the temperature of heating air; and means for circulating said heating air at a velocity between 500 fpm and 3,500 fpm over the outer surface of said drum to thereby achieve high heat conductance through said drum, wherein said circulating means includes a fan which forces said heating air into a pressurized plenum which encircles the exterior surface of said drum around its longitudinal centre.
  • a tobacco dryer further comprising a stationary cylindrical shell surrounding said drum; said shell having its central portion interrupted by and in communication with said pressurized plenum and having its end portions in communication with the suction side of said fan and also in communication with the atmosphere, said stationary shell defining with said drum a narrow annular passage over a substantial portion of said drum for guiding part of the heating air from said plenum over the exterior surface of said drum.
  • a tobacco dryer wherein a plurality of hollow paddles are arranged longitudinally on the interior surface of the drum, each of said paddles having a port through said drum in communication with said pressurized plenum; and a port being provided in said drum at each end of each of said paddles for communicating the interior of said hollow paddles with the suction side of said fan and with the atmosphere, whereby part of said heating air in said plenum is circulated by said fan through said paddles.
  • a tobacco dryer according to claim 2, wherein said means for circulating is an electrically driven fan.
  • a dryer according to claim 2 wherein the velocity of said heating air over the outer surface of said drum is 2,000 fpm.

Landscapes

  • Drying Of Solid Materials (AREA)
  • Manufacture Of Tobacco Products (AREA)
US00227693A 1972-02-17 1972-02-17 Rotary tobacco dryer Expired - Lifetime US3785765A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US22769372A 1972-02-17 1972-02-17

Publications (1)

Publication Number Publication Date
US3785765A true US3785765A (en) 1974-01-15

Family

ID=22854105

Family Applications (1)

Application Number Title Priority Date Filing Date
US00227693A Expired - Lifetime US3785765A (en) 1972-02-17 1972-02-17 Rotary tobacco dryer

Country Status (9)

Country Link
US (1) US3785765A (fr)
JP (1) JPS506556B2 (fr)
BR (1) BR7301057D0 (fr)
CA (1) CA1007447A (fr)
DE (2) DE2366052C3 (fr)
FR (1) FR2172652A5 (fr)
GB (2) GB1419151A (fr)
IT (1) IT977192B (fr)
SE (3) SE389003B (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3948277A (en) * 1972-08-18 1976-04-06 Hauni-Werke Korber & Co. Kg Method and apparatus for changing the moisture content of tobacco
EP0146759A1 (fr) * 1983-11-15 1985-07-03 Japan Tobacco Inc. Appareil pour le séchage du tabac
US4729176A (en) * 1987-04-01 1988-03-08 Productization, Inc. Rotary drum dryer and method
US4802288A (en) * 1987-04-01 1989-02-07 Productization, Inc. Rotary drum dryer and method
US6155269A (en) * 1997-11-20 2000-12-05 Brown & Williamson Tobacco Corporation Method for regulating the output humidity of tobacco
WO2020245386A1 (fr) * 2019-06-05 2020-12-10 Philip Morris Products S.A. Séchoir pour matériau herbacé ayant un collecteur en forme de canal
CN112754059A (zh) * 2021-01-30 2021-05-07 上海秀明机械设备有限公司 一种烟草均匀烘烤设备
CN112956720A (zh) * 2021-01-27 2021-06-15 上海蓬帆贸易服务中心 一种滚筒式烟叶干燥设备

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6054028B2 (ja) * 1983-12-23 1985-11-28 日本たばこ産業株式会社 たばこ用乾燥調和装置
DE3736084A1 (de) * 1987-10-24 1989-05-03 Peters Ag Claudius Drehtrommel zur erwaermung oder abkuehlung von schuettguetern
DE4022718A1 (de) * 1990-07-17 1992-01-23 Hauni Werke Koerber & Co Kg Verfahren und vorrichtung zum trocknen von tabak oder einem aehnlichen gut
DE102014218640B4 (de) * 2014-09-17 2016-05-12 Hauni Maschinenbau Ag Vorrichtung und Verfahren zum Trocknen eines Tabakmaterials
CN113303488B (zh) * 2021-04-25 2023-05-12 北京农业智能装备技术研究中心 烟草回潮控制系统
CN113349398A (zh) * 2021-06-17 2021-09-07 厦门烟草工业有限责任公司 在线调节烟草物料含水率的装置、方法及烟草加工生产线
CN113576017B (zh) * 2021-07-15 2022-09-23 河南中烟工业有限责任公司 烘丝水分控制方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2238161A (en) * 1938-04-23 1941-04-15 William F Drew Tandem rotary incinerator
US2746170A (en) * 1953-12-22 1956-05-22 Proctor And Schwartz Inc Rotary dryer
US2980117A (en) * 1956-05-08 1961-04-18 Saedeleer Albert Leopold De Equipment for moistening plants, especially tobacco
US3013785A (en) * 1958-03-24 1961-12-19 Phillips Petroleum Co Dryer temperature controls

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA596376A (en) 1960-04-19 American Machine And Foundry Company Tobacco moisture conditioning method and apparatus
GB1100017A (en) 1965-07-13 1968-01-24 Korber Kurt Apparatus for drying tobacco
GB1149524A (en) 1965-07-22 1969-04-23 Kurt Koerber Tobacco flow drying apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2238161A (en) * 1938-04-23 1941-04-15 William F Drew Tandem rotary incinerator
US2746170A (en) * 1953-12-22 1956-05-22 Proctor And Schwartz Inc Rotary dryer
US2980117A (en) * 1956-05-08 1961-04-18 Saedeleer Albert Leopold De Equipment for moistening plants, especially tobacco
US3013785A (en) * 1958-03-24 1961-12-19 Phillips Petroleum Co Dryer temperature controls

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3948277A (en) * 1972-08-18 1976-04-06 Hauni-Werke Korber & Co. Kg Method and apparatus for changing the moisture content of tobacco
EP0146759A1 (fr) * 1983-11-15 1985-07-03 Japan Tobacco Inc. Appareil pour le séchage du tabac
US4578878A (en) * 1983-11-15 1986-04-01 The Japan Tobacco & Salt Public Corporation Tobacco drying machine
US4729176A (en) * 1987-04-01 1988-03-08 Productization, Inc. Rotary drum dryer and method
US4802288A (en) * 1987-04-01 1989-02-07 Productization, Inc. Rotary drum dryer and method
US6155269A (en) * 1997-11-20 2000-12-05 Brown & Williamson Tobacco Corporation Method for regulating the output humidity of tobacco
WO2020245386A1 (fr) * 2019-06-05 2020-12-10 Philip Morris Products S.A. Séchoir pour matériau herbacé ayant un collecteur en forme de canal
US20220361554A1 (en) * 2019-06-05 2022-11-17 Philip Morris Products S.A. Dryer for herbaceous material having a channel-shaped collector
CN112956720A (zh) * 2021-01-27 2021-06-15 上海蓬帆贸易服务中心 一种滚筒式烟叶干燥设备
CN112956720B (zh) * 2021-01-27 2022-09-16 邹平双飞成套设备有限公司 一种滚筒式烟叶干燥设备
CN112754059A (zh) * 2021-01-30 2021-05-07 上海秀明机械设备有限公司 一种烟草均匀烘烤设备

Also Published As

Publication number Publication date
JPS4887096A (fr) 1973-11-16
SE7511038L (sv) 1975-10-01
SE389003B (sv) 1976-10-25
IT977192B (it) 1974-09-10
DE2305948A1 (de) 1973-08-30
JPS506556B2 (fr) 1975-03-14
DE2305948B2 (de) 1977-09-22
GB1419151A (en) 1975-12-24
FR2172652A5 (fr) 1973-09-28
DE2366052A1 (de) 1977-11-10
DE2366052B2 (de) 1978-05-24
CA1007447A (en) 1977-03-29
GB1419152A (en) 1975-12-24
DE2366052C3 (de) 1982-03-11
SE416872B (sv) 1981-02-16
BR7301057D0 (pt) 1973-12-06
SE7511039L (sv) 1975-10-01

Similar Documents

Publication Publication Date Title
US3785765A (en) Rotary tobacco dryer
US3906961A (en) Rotary tobacco dryer
JPH02504469A (ja) ロータリシリンダ式ドライヤ
US3325912A (en) Apparatus for treatment of loose materials with gaseous mediums
US4127945A (en) Process and a dryer for drying polychloroprene sheets
US4205458A (en) Method and apparatus for drying particulate material
JP2002069458A (ja) 粉粒体の乾燥装置
US3905127A (en) Apparatus for drying heat sensitive particulate material
US4854941A (en) Method and apparatus for drying fine coal
US2126426A (en) Drying apparatus
US1964858A (en) Method and apparatus for treatment of nongaseous materials
JP7064338B2 (ja) 間接加熱型汚泥乾燥装置
US4945930A (en) Apparatus for expanding and/or drying particulate material
US3171639A (en) Dryer control apparatus
CN2119622U (zh) 负压喷腾式滚筒烘干机
GB1440525A (en) Method and apparatus for drying and heating fluent materials
US3156455A (en) Methods of effecting heat exchange and heat transfer devices therefor
US923092A (en) Drying mechanism.
US765666A (en) Drying apparatus.
US4668185A (en) Process and apparatus for drying organic material in a rotary dryer
CN221147116U (zh) 一种喷射气流带式干燥机
US3269029A (en) Jet spiral drier
US1086092A (en) Drier.
US333825A (en) Drier
SU1118837A1 (ru) Сушилка дл сыпучих материалов