Title:
Process for shaping a pulp, mash or slurry into smokable fibers
United States Patent 3872870


Abstract:
Method for the formation of smoking fibers which may or may not contain tobacco, in which a pulp, mash or slurry of the smokeable composition is extruded through orifices upwardly into a vortex chamber while a drying gas is passed in the same direction around the fibers as they are formed so that the extruded strands are broken up into discrete lengths. The gas flow is controlled so that, at the top of the drying chamber, only dry fibers are entrained with the gas and are separated out in a gas/fiber separator downstream of the vortex chamber. Upwardly carried moist fibers return downwardly until they are sufficiently light to be entrained out of the system.



Inventors:
Buchmann, Paul (Basel, CH)
Beringer, Monique (Saint Louis, FR)
Sporri, Heinz (Birsfelden, CH)
Application Number:
05/425133
Publication Date:
03/25/1975
Filing Date:
12/17/1973
Assignee:
Tamag Basel AG (Basel, CH)
Primary Class:
Other Classes:
131/369
International Classes:
A24B15/12; (IPC1-7): A24B3/14
Field of Search:
264/12,13 425
View Patent Images:
US Patent References:
3508296MELT SPINNING APPARATUS1970-04-28Ono
3389429Spinning apparatus1968-06-25Montgomery
3373751Method in utilizing and refining tobacco dust and waste1968-03-19Wallberg
3025860Method of producing tobacco-containing foils1962-03-20Grossteinbeck et al.



Primary Examiner:
Rein, Melvin D.
Attorney, Agent or Firm:
Ross, Karl Dubno Herbert F.
Claims:
We claim

1. A process for making smokeable fibers comprising the steps of forming a shapeable smokeable composition into fiber strands; passing said strands upwardly while entraining them in a drying gas stream to set the strand and form dry fibers which are lighter than moist fibers; entraining the dry fibers upwardly in said gas stream upon their drying; and maintaining a circulation of moist fibers in said gas stream until said moist fibers become sufficiently light by drying to be entrained with said gas stream.

2. The method defined in claim 1 wherein said composition is extruded upwardly through orifices at the bottom of a drying chamber, further comprising the step of entraining said strands upwardly immediately upon their passage from said orifices in streams of the gas passed upwardly at said orifices.

3. The method defined in claim 2 further comprising the steps of inducing a vortex movement of gas and fibers in said chamber about a vertical axis, removing the gas and the dry fibers at an upper portion of said vortex movement in a generally tangential direction, and establishing a velocity gradient in said chamber from a relatively high velocity adjacent said orifices to a relatively low velocity at the upper portion of said chamber.

4. The method defined in claim 3 wherein said gas is air further comprising the step of pulsing the rate at which air is admitted to the chamber to subdivide said strands into fibers.

5. The method defined in claim 3 further comprising the step of pulsing the pressure of said composition and said orifices to subdivide said strands into fibers.

Description:
FIELD OF THE INVENTION

The invention relates to a process for shaping a pulp into smokable fibers.

BACKGROUND OF THE INVENTION

In the commonly assigned copending application Ser. No. 194,654 filed Nov. 1 1971 (now U.S. Pat. No. 3,820,548) we have described the manufacture of smokeable materials wherein a composition consisting basically of comminuted botanicals nontobacco and tobacco plants), binders, mineral fillers and plasticizers, is formed into a pulp, mash, slurry, suspension or paste in water and shaped and dried. In that application the composition, which may also be used in the present method and apparatus, was shaped by casting the slurry upon a surface and drying the material on the surface to form a foil which was comminuted to produce discrete strands or fibers.

It should be apparent that this process and others whereby a continuous film, foil, sheet or layer must be formed before the latter can be subdivided into strands or fibers is undesirable because of the process costs.

It has been proposed to avoid the step of preliminarily forming the sheet by extruding strands of a dryable composition and causing the strands or fibers thus produced to fall downwardly into a drying chamber in which the fibers pass in counterflow to a hot air stream. The fibers collected on the bottom are more or less completely dry.

However, these processes have the general disadvantage that because of Stoke's Law the lighter fibers may be partially suspended whereas the heavier fibers, i.e., those which are still moist, may fall more rapidly against the rising air stream. As a consequence some moist fibers may be collected at the bottom while dry fibers are kept unnecessarily long in the drying chamber.

In a known apparatus of this kind, the fibers are fed from above into a vortex chamber and are dried in the oppositely flowing hot air stream. The dry fibers drop downwardly out of the vortex chamber which is open at the bottom.

In the latter apparatus, to avoid the abovementioned disadvantage whereby moist particles may fall rapidly through the system, the fibers must be maintained in the vortex for a period sufficient to guarantee complete drying. As a consequence, certain fibers may be retained unnecessarily long in circulation within the vortex chamber, thereby increasing the energy requirements for operating the drying system.

OBJECTS OF THE INVENTION

It is the present object of the present invention to provide an improved method of making a smokeable fiber whereby the aforementioned disadvantages are obviated.

It is another object of the invention to provide an improved method of drying smokeable fibers with minimum energy costs and maximum throughput.

It is an other object of the invention to develop a process for the purposes described whereby the fibers are discharged from the drying gas stream, preferably a hot air stream, only after they have been sufficiently dried.

SUMMARY OF THE INVENTION

The aforedescribed objects are attained, in accordance with the present invention, in a method of producing smokeable fibers in which a dryable paste, pulp, mash or slurry (more generally a dryable extrudable composition) is shaped into discrete fiber-like strands, the strands are passed upwardly into a codirectionally moving drying gas stream and are admitted to a vortex chamber in which the discrete fibers whirl around in the drying gas, and the dry fibers are entrained between the drying gas in the same direction whereas the moist fibers are retained in the vortex chamber until they also have dried.

According to the invention, the velocity of the gas within the chamber is caused to decrease upwardly from the strand-forming portion to the outlet such that at the strand-forming portion the gas velocity is sufficient to entrain the fully moist fibers in a vortex movement whereas toward the outlet the velocity is only sufficient to entrain the fully dried and hence lighter fibers along with the gas stream. The vortex chamber, therefore, may be of upper diverging configuration and hence of upwardly increasing cross section to obtain the desired negative gradient of velocity in the upward direction. The system thus uses fluidized bed principles in which a substantially turbulent fluidized bed of suspended moist fibers is maintained at least at the lower portion of the drying chamber, as well as gas-classification principles whereby the sufficiently light and hence fully dried fibers may be carried off by the fluidizing gas stream.

Preferably, the composition which is employed consists essentially of comminuted tobacco and/or nontobacco botanicals as described in the aforementioned copending application, inorganic or organic salts as fillers, binders and plasticizers. The drying gas is preferably air.

The process in accordance with the invention is thus characterised by the feature that the dry fibers are separated from the moist fibers by upward entrainment by the gas stream.

The invention makes use of the fact that the dried fibers are lighter than those still moist. Consequently the dried fibers are preferentially carried upwardly by the gas stream or the hot air stream against the action of gravity and can be discharged, whereas the still moist fibers, because of their higher weight, remain in the lower region of the gas flow and, if they should accidentally reach the higher region, drop back immediately until they are finally sufficiently dried and become light enough to be discharged upwardly.

The moist fibers during their shaping are preferably surrounded by the gas stream which flows in the same direction as the pulp being formed into fibers. The fibers at a critical point in their production are thus immediately enveloped by the gas stream and thereby dried, at least externally, so that they retain the elongated form as obtained upon extrusion from the nozzle. They are also stretched by partial frictional entrainment by the gas stream, removed from the nozzle and prevented from adhering to the adjacent fibers. By the gas stream enveloping the fibers as they are formed, the fibers on reaching a certain length are torn from the nozzle and the operating conditions may readily be so chosen that the fibers are produced from the start with the finally required length.

The instant at which they are torn off may also be predetermined in that the gas stream enveloping the fibers is pulsed and/or the pressure at which the pulp is fed to the extrusion nozzle is pulsed.

The pulsing of the extrudable paste or the entraining drying gas creates a pressure shock at intervals which causes separation of the extruded strand into discrete fibers. If the codirectionally moving gas is considered to be a constant source of friction drawing the strands out of the extrusion orifices, the instantaneous pulsing of the extrudable composition will momentarily weaken the ligature connecting the strand with the mass of extrudable matter at the orifice and hence the constant friction force will break the previously extruded length of strand away from the mass of the paste or pulp.

When the paste or pulp is extruded with a constant pressure, however, and the entraining gas is pulsed, the momentary increase in velocity of the entraining gas increases the force upon the previously extruded length of the strand and causes the latter to break away in the orifice. Of course both pulsation of the extrudable mass and pulsation of the entraining gas (synchronously) can be used, in which case both principles apply.

The invention also comprises an apparatus for carrying out the process whereby, in simple manner, the completely dried fibers are discharged so that they may be further processed into smokable articles.

The apparatus for carrying out the process, includes a vortex chamber traversed upwardly by a gas stream into which an extruding nozzle connected to a pulp storage and a pressure source for this pulp and provided with several pulp outlet openings is directed.

The extrusion nozzle is located at the bottom in the vorex chamber and has its orifices directed upwardly while an outlet opening formed at the top in the vortex chamber for the gas stream leads into a fiber separator which permits the fibers carried along by the emerging gas stream to drop downwardly, the gas being drawn off in another direction.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a vertical section, partly in diagrammatic form showing an embodiment of the apparatus in accordance with the invention; and

FIG. 2 is a section taken along the line II-II through the vortex chamber of FIG. 1, only half the section being shown.

SPECIFIC DESCRIPTION

In the drawing a vortex chamber is generally denoted by 60, the housing 61 of which is enlarged widened upwardly rotationally symmetrical relative to the axis 62. The lower part of the vortex chamber is formed as an extrusion nozzle 63, the nozzle orifice of which is a base plate 64 which divides a cavity 65 and has a plurality of pulp outlet openings 66 formed therein between which compressed air openings 67 are formed, as shown in FIG. 2, so that each pulp outlet opening 66 is adjacent at least to one compressed air opening 67.

The pulp outlet openings 66 on the one hand and the compressed air openings 67 on the other hand are uniformly distributed over the base plate 64 and the bore axes of these extend parallel to the central axis 62. The pulp outlet openings emanate from the cavity 65, while the compressed air openings are connected via pipe sockets 68 to a compressed air ring conduit 69 accommodated in the cavity 65, which conduit in turn is connected via a socket 70 led out of the cavity with interposition of an impulse generator 71 to the pressure side of the compressed air blower 72, which via an air heater 73 induces air from the atmosphere.

The cavity 65 is connected via a pulp supply fitting 74 to the pressure side of a pulp pump 75 which extracts pulp from a pulp storage means 76 and pumps it with pressure into the cavity 65. The numeral 77 denotes an impulse generator which is connected to the pump 75 and superimposes pressure pulses upon the hydraulic delivery pressure of the pulp.

Two rings of air nozzles 78, 79 are provided which communicate with the external atmosphere and lead into the interior of the vortex chamber 60, as is evident from the nozzles 78 of FIG. 2, and are directed in the same direction of rotation, relative to the axis 62 in accordance with the arrows 86 which are shown in FIG. 2.

In the upper region of the vortex chamber an air outlet opening 80 is formed which is tangential to the vortex space in the direction of the flow circulating in accordance with the arrow 86, by a pipe 81 which leads to a fiber separator 82.

The fiber separator 82 consists substantially of a T-shaped pipe section 83 connected to the pipe 81 and which extends vertically and is open at the bottom, so that the fibers 84 carried by the air stream may fall out for further processing.

The upper end is connected to the suction side of blower 85 leading into the atmosphere at the pressure side.

The pressure side of the blower 85 may be connected to the suction side of the air heater 73 and/or connected at the outside to the air nozzles 78, 79. The numeral 89 denotes an additional material storage means, which for example may be filled with glycerine, from which a pump 87 by means of a nozzle system 88 located in the socket 81 blows this liquid additive against the tobacco fibers already setting and hence coating these.

The mode of operation of the apparatus is as follows. Driven by the pump 75, pulp is forced into the cavity 65 and extruded from the pulp outlet openings 66 in small strands, at the same time hot air is driven by the blower 72 and expelled through the air outlet openings 67 and flows around the fibers just forming during the discharge of the pulp from the pulp out let openings 66 and hence maintaining them upright and thus substantially parallel to the axis 66, and finally carrying them along, whereby tear-off is determined by the impulse strokes of the impulse generator 77 and/or the impulse generator 71.

One of the impulse generators 71 and 77 is dispensable. Both impulse generators may be abandoned if the fibers formed are to be torn off statistically when they have attained a certain length dependent upon the operating conditions of pulp consistancy and geometry of the nozzle. Air enters from the nozzles 78 and 79 into the vortex chamber induced through the blower 85 which in the form of a cyclone flows upwards about the axis 62. The flow is most intensive in the lower region of the chamber, because the chamber at this point is narrowest. The still moist fibers are carried along by these streams and lifted slightly and whirled about until they are finally dry and then, since they have become lighter in the meantime, are forcibly carried along upwards completely and then together with the air stream leave through the socket 81 the vortex chamber. The fibers 84 drop out of the fiber separator 82 downwardly, while the air is extracted upwardly by the blower 85.

The wall of the housing 61 may be made heatable and/or internally provided with wall heat radiators, such as infra-red radiators, to promote the drying of the fibers whirled about the vortex chamber. The additives, instead of being introduced by the nozzle system 88, may be injected by pipe 81 or additionally thereto also injected within the vortex chamber 60 preferably in the lower region thereof. The air throughput through the vortex chamber 60 is conveniently controlled in dependence upon the degree of moisture of the fibers to be dried, so that, when the fibers are very damp, the dwell period thereof in the vortex chamber is correspondingly longer.

The invention may be used when producing smokable fibers of tobacco or tobacco wastes and by employing, and co-employing botanicals respectively which are not tobacco plants -- so-called non-tobacco plants.

SPECIFIC EXAMPLES

Example 1

1,000 grams wheat crush, 1,000 grams wheat straw, 1,000 grams rice chaff, 1,000 grams oat straw, 500 grams coconut shells with fibers and 500 grams cacao shells were ground in a dry state, suspended with 15 liters of water and the suspension milled in a wet state at a maximum temperature of +60°C.

Into the suspension so formed the following components are charged: 50 grams magnesium formate, 300 grams tartaric acid, 100 grams potassium nitrate, 400 grams diammonium hydrogen phosphate, 7.5 grams vanillin, 400 grams calcium carbonate, 450 grams liquid paraffin, 900 grams NaCMC, 200 grams raw pectin, 150 grams 40 percent glyoxal, 100 grams glycerine, 650 grams diethylene glycol, 850 grams fruit concentrate, 500 grams invert sugar and 50 grams coffee bean residues and the mixture so formed is kneaded in a kneading machine to form a homogenous pulp. (NaCMC = sodium carboxymethylcellulose).

The pulp produced in this manner is charged into the pulp storage container 76 in accordance with FIG. 1 and, as described, is extruded. The pump 87 is hence not in operation.

Example 2

5,000 grams natural tobacco wastes are ground in a dry state, suspended with 15 liters of water and the suspension ground in a wet state at a maximum temperature of 60°C.

Into the suspension so formed the following components are charged: 50 grams magnesium formate, 500 grams NaCMC, 200 grams glycerine and 100 grams 40 percent glyoxal and the mixture so formed kneaded in a kneading machine into a homogenous pulp. The pulp produced in this manner is charged into a pulp storage container 76 in accordance with FIG. 1 and extruded into fibers as described in the particular description. The pump 87 is hence in operation and the additive storage 89 charged with glycerine which is sprayed on the fibers.

All weight data in the Examples relate to the pulp components with their natural water and water of crystallisation content respectively.