GB2155302A - Process for expanding tobacco leaves and apparatus therefor - Google Patents

Abstract

Tobacco stems are expanded in an expanding tube (1) maintained at predetermined temperature by a water bath (10). This tube is in connection with a delivery tube (7) from a supply source (8) via a connection tube (3), forming a tubular system which is wholly hermetically sealed from the outside atmosphere. A high pressure gas is jelled from jetting nozzle (9') disposed within the connection tube section and at once introduced into said expanding tube by passing through a passage (A) of venturi type, where by the cut tobacco stems are sucked from the source through the delivery tube and into said expanding tube by the suction power generated, as if they were injected thereinto accompanying the high pressure gas. <IMAGE>

Description

SPECIFICATION Process for expanding tobacco leaves and apparatus therefor This invention relates to a process for expanding tobacco stems/leaves utilizing a gas under pressure and to an apparatus therefor.

A process in which shredded tobacco leaves including midribs are expanded by being injected into an expanding tube with the aid of steam at an elevated temperature under an elevated pressure is disclosed in Korean Patent Publication No. 1620/ 1981.

In that process there is provided a hopper open to one side of the inlet of an expanding tube, and it is so designed that when cut tobacco stems are introduced into said hopper and then steam is jetted from a steam jetting device provided at the inlet of said expanding tube, by virtue of the steam jetting power said cut tobacco stems within the hopper can be expanded while being injected into said expanding tube. The expanding of the cut tobacco stems thus injected into the expanding tube can be smoothly achieved at any rate, but in the operation involving the injection of cut tobacco stems into said expanding tube there are some problems.

That is to say, in the above described process cut tobacco stems should be charged into the hopper, but for the purpose, in order to transfer the tobacco (which has been cut in a cutting machine) to the hopper it is necessary to install side by side a power equipment such as a transferring apparatus of conveyor type, a transferring apparatus of screw type, or a shifter of vibration type, etc., so that various economic disadvantages such as complication of equipment, occupation of large space, increased cost of equipment, etc., are inevitably incurred. Another important disadvantage is that, when the cut tobacco stems within the hopper are injected into the expanding tube by the steam jetting power, such loud noises are generated that no one can conduct operations without muffler equipment.

This presents a problem which is difficult to overcome.

To mention yet another disadvantage in the process for expanding utilizing such a U-shaped expanding tube, it should be pointed out that since said expanding tube is maintained at a high temperature by the use of steam at a high temperature under a high pressure, muddy powder adheres onto the inner walls of the expanding tube. As a result the operation often has to be interrupted.

Thus, this invention seeks to provide a process for expanding tobacco stems and an apparatus therefor, in which cut tobacco stems can be smoothly transferred to the expanding tube without the necessity of providing any mechanical means, such as conveyors or other power equipment. Preferably, at the same time the stems should be able to be expanded by being injected into said expanding tube without being accompanied by noises and even without causing the muddy powder of tobacco to adhere to the expanding tube.

In accordance with this invention a passage of venturi tube type is formed at one end of the expanding tube so that the gas to be sent into the expanding tube passes through this venturi passage. By allowing the jet of gas to pass through the venturi passage prior to its flowing into the Ushaped expanding tube shredded tobacco leaves are transferred into the expanding tube by virtue of the suction power generated. In the above case it is necessary that for the prevention of noises caused by the jetting of the high pressure gas the expanding tube and the delivery tube for the supply of cut rolled stems are mutually connected and moreover such connection of these two tubes is hermetically sealed from the outside atmosphere.

When the high pressure gas, especially air or steam, jetted from a high pressure gas supplying tube, passes through the venturi passage, its motion is accelerative, so that a reduced pressure makes its appearance around the gas supplying nozzle outside the passage, and as a result the cut rolled stems in the supply source thereof are sucked into the delivery tube and injected into said expanding tube. The noise then caused due to the divergence of the high pressure gas is transmitted into the delivery tube but, as it is absorbed by the cut tobacco stems transferred into the delivery tube, the noise appearing on the outside is markedly reduced.

The invention and preferred features of it are further defined in the appended claims.

This invention will be more fully explained below with reference to Figures 1 and 2 of the accompanying drawings.

Figure 1 of the drawings is a schematic side view of an apparatus according to this invention and Figure 2 is a cross-sectional view of the important part of Figure 1.

Referring to the drawings, a U-shaped expanding tube 1, one end of which is in communication with a cyclone 2 for the separation of water vapour, is provided with a connecting tube 3 having a passage A of venturi form at its other end. (The connecting tube 3 may be made of metal, but it is preferably made of a high-strength material having a silencing effect.) The connecting tube 3 and the expanding tube 1 have the same diameter where they join and near their junction there is provided inside one of the tubes a protruding portion 4 which forms a passage A of venturi-tube type, whilst towards the other end of the connecting tube 3 beyond the protruding portion 4 there is formed an enlarged region 5 whose terminal portion is hermetically sealed to a blocking plate 6.

The upper end of a bent delivery tube 7 for cut tobacco stems opens through one side of the blocking plate 6 under hermetically sealed conditions, and the lower end of the tube 7 is connected to the source of supply of cut rolled stems, constructed so as to function as a feeding device 8' for cut rolled tobacco stems from a cutting machine 8.

(It is desirable that the delivery tube 7 in this appa ratus is made of metal, synthetic resin, or woven fabric through which noise is poorly transmitted.) In the part of the blocking plate 6 which is in coaxial alignment with the expanding tube 1 there is provided a high pressure gas supply tube 9 which is coaxial with the expanding tube 1, and the end of the jetting nozzle 9' of the supply tube 9 is arranged to protrude within the connecting tube 3 so that it is positioned above the venturi passage A.

As the venturi passage A serves to transfer the shredded tobacco leaves into the expanding tube 1 by virtue of its suction power exhibited when the high pressure gas is jetted through the high pressure gas jetting nozzle 9', it is possible to provide this passage A at the end of the expanding tube 1 instead of within connecting tube 3. In this case, however, it is necessary to adjust the distance between the supply tube 9 and the nozzle 9' suitably.

If a high pressure gas, especially high pressure air or steam, is jetted from the nozzle 9' of the supply tube 9, the flow velocity of the high pressure gas increases when it passes through the venturi passage A and as a result a pressure reduction is set up within injecting passage B for cut tobacco stems formed on one side of the nozzle 9'. This generates a power of suction strong enough to suck the cut tobacco stems into the delivery tube 7.

The cut tobacco stems pass through the delivery tube 7, are sucked into the connecting tube 3, and thence are injected into the expanding tube 1 accompanying the high pressure gas.

(It is desirable that the gas jetted from the nozzle 9' of the high pressure gas supply tube 9 has a flow velocity of 200 to 500 m/s and a jetting pressure of 1.0-1.5 kg/cm2. The suction velocity of the cut tobacco stems into the delivery tube 7 is preferably 20-50 mis.) The expanding tube 1 is surrounded with a thermostatically controlled water tank 10 equipped with a cold water supply tube 11, a steam supply tube 12, and a draining tube 13. Furthermore, the connection between the expanding tube 1 and the cylone 2, i.e. the discharge end 1' of the expanding tube 1, is surrounded with a cold water tank 14 equipped with a cold water supply tube 15 and a draining tube 16.

(The thermostatically controlled water tank 10 and the cold water tank 14 are necessary to prevent the adhesion of muddy powder which occurs on every part inside the expanding tube 1 when the cut tobacco stems are swollen, and it is preferable that the internal temperature of the water tank 10 is maintained at 88-98"C by operating the valves attached to cold water supply tube 11, the steam supply tube 12, and the draining tube 13, respectively, and that the temperature of the cold water tank 14 is maintained at 40-60"C by adjusting the supply of cooling water.) The discharge end 1' of the expanding tube 1 is in connection with the cyclone 2 the upper end of which is equipped with an exhaust duct 17 to separate water vapour for removal and the lower end of which is equipped with a discharge device 18 for the expanded cut tobacco stems so that the expanded tobacco stems can be transferred to subsequent processing steps such as drying, etc. Also, around the cyclone 2, on its external wall 19 there is formed a heating jacket equipped with a steam supply tube 20 and a draining tube 21 in order to prevent the condensation of the water vapour by maintaining the temperature above 110 C.

In accordance with this invention, as above described, the cut tobacco stems from the tobacco supply source are sucked through the delivery tube 7 into the expanding tube 1 by virtue of the suction power generated when the high pressure gas jetted from nozzle 9' passes through the venturi passage A, so that not only does it become unnecessary to install any power equipment such as conveyor means, etc. that are required to transfer the tobacco leaves to the entrance of the expanding tube 1 in the conventional process, thus saving the cost of equipment, but also it becomes possible to absorb the noise, which is inherently produced when a high pressure gas is jetted as well as cut tobacco stems are injected into expanding tube by the action of a high pressure gas, in the cut tobacco stems being transferred through the delivery tube. Thus, the operational disturbance can be entirely avoided, almost without transmitting the noise to the outside of the expanding device in practice. In addition to the above, in this invention, in which the thermostatically controlled water tank and the cooling water tank are provided around the expanding tube so as to maintain the temperature of the expanding tube constant, muddy powder within the expanding tube can be prevented from adhering to it and this is also remarkably advantageous in enhancing the operational efficiency.

Claims (14)

1. A process for expanding tobacco stems comprising sucking the tobacco stems through a hermetically sealed connection tube system into an expanding tube by means of suction power generated by passage of a jet of gas into the expanding tube through a venturi constriction, and casuing the tobacco stems to expand in the expanding tube under a regulated, elevated temperature.

2. A process as claimed in claim 1 wherein the expanding tube is maintained under a substantially constant elevated temperature by means of a thermostatically controlled water bath.

3. A process for expanding tobacco stems, in which cut tobacco stems are introduced into a Ushaped expanding tube along with a high pressure gas, which process is characterized in that the temperature of the U-shaped expanding tube is maintained at the temperature of a thermostatically controlled water tank surrounding it, the U-shaped expanding tube being in connection with a delivery tube from a supply source of cut tobacco stems via a connection tube, forming a tubular system which is hermetically sealed from the outside atmosphere, and as soon as a high pressure gas is jetted from a jetting nozzle disposed within the connection tube in the tubular system the high pressure gas is at once introduced into said expanding tube and passes through a passage of venturi type formed on the way, whereby by utilizing the suction power generated the cut tobacco stems are sucked from their supply source via the delivery tube, and are fed into said expanding tube as if they were injected thereinto accompanying the high pressure gas and are caused to be swollen in said expanding tube.

4. A process as claimed in any of claims 1 to 3, wherein the gas is air or steam.

5. A process as claimed in any of claims 1 to 4 wherein the gas has been preliminarily heated to 50 to 250"C.

6. A process as claimed in any of claims 1 to 5, wherein the gas is jetted into the venturi passage at a jetting speed of 200-500 m/s.

7. A process as claimed in any of claims 1 to 6, wherein the temperature of the main portion of the expanding tube is maintained at 88"-98"C and the temperature of the discharge end of the expanding tube is maintained at 40-600C.

8. A process for expanding tobacco stems as claimed in claim 1 and carried out substantially as hereinbefore described.

9. An apparatus for expanding cut tobacco stems, comprising a U-shaped expanding tube surrounded by a thermostatically controlled temperature regulating means and connected to a delivery tube from a supply source of cut tobacco stems via a connection tube, thereby forming a tubular system which is hermetically sealed from the outside atmosphere, said tubular system being provided with a jetting nozzle for gas under pressure within the connection tube as well as a passage of venturi type formed between said jetting nozzle and the inlet portion of the expanding tube, and a cyclone for the separation of water vapour in communication with the discharge end of the expanding tube.

10. Apparatus as claimed in claim 9, wherein the passage of venturi type is formed within the connection tube.

11. Apparatus as claimed in claim 9, wherein the passage of venturi type is formed within the inlet portion of the expanding tube.

12. Apparatus as claimed in any of claims 9 to 11, wherein the delivery tube is made of metal, synthetic resin, or woven fabric.

13. Apparatus as claimed in any of claims 9 to 12, wherein the U-shaped expanding tube is surrounded by a thermostatically controlled water tank.

14. Apparatus as claimed in any of claims 9 to 13, wherein the discharge end of the U-shaped expanding tube is surrounded by a cooling jacket.