Method for improving the filling ability of tobacco

Abstract

The invention relates to a method for improving the fillability of tobacco, as tobacco leaves or ribs and/or tobacco additives, by treatment of the tobacco material, which has approx. up to 15 wt. % initial moisture with a treatment gas consisting of nitrogen and/or argon at pressures of 50 to 1,000 bar with continuous or graduated compression followed by continuous or graduated decompression, with the compression and decompression stages taking place in either one autoclave or with cascade-type switching in several autoclaves, followed by thermal after-treatment of the tobacco material discharged, which is characterised in that the compression is carried out at an operating temperature above 55° C., preferably at 60 to 90° C. and the initial moisture of the tobacco material lies within the range 8 to 14 wt. %.

Description

[0001] The invention relates to a method for improving the fillability of tobacco, as cut tobacco leaves or ribs and/or tobacco additives, by treatment of the tobacco material, which initially has up to 15 wt. % moisture with a treatment gas consisting of nitrogen and/or argon at pressures of 50 to 1,000 bar with continuous or graduated compression followed by continuous or graduated decompression, in which the compression or decompression stages take place in either an autoclave or with cascade-type switching in several autoclaves, followed by thermal after-treatment of the tobacco material discharged.

[0002] Methods of this kind, which are also known as INCOM expansion methods, have proved to be advantageous compared with the pressure treatment of tobacco with carbon dioxide, ammonia or volatile organic gases. Thus DE 31 19 330 A1 describes such an expansion method with operating temperatures of 0 to 50° C. prevailing in the autoclave, wherein to increase the fillability or the degree of expansion, use of a tobacco material with moisture of up to 15 wt. % and after-treatment with water vapour was provided. In this case the aim was that lower moisture of the tobacco of 10 to 15 wt. % would lead to a desired greater cooling of the tobacco material to be discharged when the tension was released.

[0003] Furthermore, DE 34 14 625 C2 discloses a cascade method, according to which, by the most widely varying measures such as cooling of the treatment gas before loading of the reactor, cooling of the autoclaves or use of an undercooled and liquefied treatment gas, a low operating temperature is to be effected during impregnation of the tobacco. It is true that the tobacco moisture may lie anywhere, for instance within the range of 10-30 wt. %, however it is expressly required that the autoclave temperature and/or its cooling water temperature must not exceed 50° C.

[0004] This is also confirmed according to DE 39 35 774 C2 in connection with a cascade-type expansion method, in which circulation of the treatment gas via a cooler is provided, in order to keep to the necessary low impregnation temperatures of 25 or 45° C.

[0005] Although good values have already been achieved with the aforementioned expansion methods with regard to increasing the fillability of tobacco and/or the degree of expansion, these are relatively expensive because of the necessary cooling of the autoclave or autoclaves and because of the additional cooling of the treatment gas.

[0006] The aim of the invention is to improve the existing INCOM methods and with equally good or better values with regard to fillability or expansion effect, to avoid the uneconomical cooling measures during compression which have hitherto been regarded as necessary.

[0007] According to the invention a method of the type initially mentioned according to the preamble to the patent claim, is therefore proposed, which is characterised by the fact that the compression is carried out at a reactor temperature of above 55° C.

[0008] Surprisingly it has transpired that in the case of low tobacco moistures within the range of up to 15 wt. % the existing theory, which requires a low treatment temperature, does not lead to optimum expansion results. On the contrary, only by increasing the treatment temperature during compression was it possible to achieve surprisingly good values with regard to the expansion effect and/or fillability.

[0009] Furthermore, according to the method, this leads to the advantage, that the heat of compression does not have to be eliminated, and thus no additional cooling of the autoclave or autoclaves is necessary.

[0010] In the following example, the method according to the invention is explained in comparison with the existing state of the art. The test results show the differing influence of the operating temperature on the degree of expansion for different tobacco moistures. According to the existing theory, in the case of tobacco moisture of 18 wt. %, increasing the operating temperature above 40° C. leads to a deterioration in the expansion effect. On the other hand, in the case of tobacco moistures of below 15 wt. %, clear improvements appear if the high pressure treatment is carried out at operating temperatures of 60 and 80° C. Surprisingly the achievable degrees of expansion with low tobacco moisture and higher operating temperatures are even in some cases above the values achieved under conventional conditions.

EXAMPLE

[0011] The high pressure treatment was carried out in a laboratory autoclave with a used content of 2l . A casing for circulation of liquid media was used to adjust the desired operating temperatures. The build-up of pressure was carried out from below, the reduction in pressure upwards. Several valves made the intended circuit diagrams possible. A compressor was used to adjust the final pressure. A thermocouple element measured the tobacco temperature in the upper tobacco filling section.

[0012] The laboratory device for thermal after-treatment consisted of a permeable wire gauze serving as a conveyor belt, baffles for formation of the tobacco mat in the desired width, a steam nozzle with slit-type outlet and a steam suction device arranged under the belt. The after-treatment was carried out with saturated steam.

[0013] The most important treatment parameters are shown by the following Table 1.

	TABLE 1
	High pressure treatment	Thermal after-treatment
	Gas supply	from below	Steaming	about 10 kg/h
			capacity
	Gas outlet	upwards	Slit nozzle	about 8 mm
	Tobacco	300 g	Slit width	about 160 mm
	quantity
	Tobacco	PVC pipe/	Transport	about 5 cm/s
	container	perforated
		bottom

[0014] The tobacco samples were spread out in flat plastic trays and conditioned in the standard climate at 21° C. and 62% relative humidity. The fillabilities were determined using a Borgwaldt density meter, and the specific volume in ml/g converted for a nominal moisture of 12 wt. % and a nominal temperature of 22° C. From the data of the untreated comparison/base specimens and the expanded specimens, the relative improvement in fillability, which is also described as the degree of expansion, can be calculated according to the following formula, in which FB means the fillability of the base and FE means the fillability of the expanded tobacco:

Δ%=(FE−FB)*100%/FB

[0015] The tests were carried out with tobacco moistures of 8, 12 and 14 and 18 wt. % as a comparison. The operating temperatures were adjusted by thermostatic control to 40, 60 and 80° C. The final pressure amounted to 700 bar, the pressure reduction was carried out in a time interval of approx. 0.5 min. All the tests were based on a uniform mixture of Virginia tobaccos and the after-treatment method with saturated steam described.

[0016] The results of the tests are represented in the following Table 2, and those of the comparative test in the following Table 2a. In the tables TA means the tobacco temperature immediately before removal from the autoclave as discharge temperature and Δ% means the relative improvement in fillability and/or degree of expansion.

	TABLE 2
	Tobacco moisture 8 wt. %	Tobacco moisture 12 wt. %	Tobacco moisture 14 wt. %
Operating temperature ° C.	TA ° C.	Δ %	TA ° C.	Δ %	TA ° C.	Δ %
40	−61	59	−53	70	−48	76
60	−48	70	−25	79	−18	83
80	−15	78	−3	81	0	73

[0017]

	TABLE 2a
	Tobacco moisture 18 wt. %
Operating temperature ° C.	TA ° C.	Δ %
40	−41	80
60	−12	76
80	1	54

[0018] Comparison of the above tables clearly shows the positive effect of higher operating temperatures of 60 and 80° C. on the improvement of fillability, if tobacco with moistures of less than 15 wt. % is used.

Claims

1. Method for improving the fillability of tobacco, as cut tobacco leaves or ribs and/or tobacco additives, by treatment of the tobacco material, which has up to approx. 15 wt. % initial moisture with a treatment gas consisting of nitrogen and/or argon at pressures of 50 to 1,000 bar with continuous or graduated compression followed by continuous or graduated decompression, the compression or decompression stages being carried out in either one autoclave or with cascade-type switching in several autoclaves, followed by thermal after-treatment of the tobacco material discharged, characterised in that the compression is carried out at an operating temperature above 55° C.

2. Method according to claim 1, characterised in that the compression is carried out at an operating temperature of 60 to 90° C.

3. Method according to claim 1, characterised in that the initial moisture of the tobacco material lies within the range 8 to 14 wt. %.