FI89324C - REQUIREMENTS FOR SEPARATION OF SEPARATED SEPARATION AV NIKOTIN FRAON ETT LOESNINGSMEDEL - Google Patents

Description

! 89324

Method and apparatus for the semi-continuous separation of nicotine from solvent Förfarande och anordning för semikontinuerlig separation av nicotin frän ett lösningsmedel

The present invention relates to separation measures and in particular to a process for the semi-continuous separation of nicotine from a solvent. In particular, the present invention can be applied to separate nicotine from the solvent used to selectively extract nicotine from tobacco.

Numerous methods have been proposed for removing nicotine from tobacco. However, most of these methods adversely affect the desired taste and aroma properties of the tobacco. Likewise, their implementation is often complex and expensive.

U.S. Patent No. 4,153,063 describes a method for extracting nicotine from tobacco as a solvent in a supercritical state. In a multi-stage extraction process, the arorn components are first extracted from the dry tobacco as a solvent in a supercritical state. The nicotine is then extracted from the moist tobacco into a supercritical solvent, from which it is separated either by evaporating the solvent, contacting the solvent with the acid in a separate vessel, or adsorbing the nicotine onto an activated carbon column. Finally, the stored arorn components from the first step are redissolved in the supercritical solvent and returned to the tobacco.

U.S. Patent No. 3,139,435 discloses the extraction of nicotine as a solvent in a series of extraction vessels and the separation of nicotine from this solvent in a single extraction column by a liquid / liquid extraction process in which the solvent is contacted with countercurrent cold saline. U.S. Patent No. 1,196,184 discloses the extraction of nicotine from tobacco with a solvent from which nicotine is separated by 2 B9324 liquid / liquid contact. LU patent publication 82835 discloses a plant product extraction process similar to the previous methods, comprising a series of vessels for extracting plant products for extracting the soluble constituents of plants. The extracted ingredients are separated from the solvent by liquefying the solvent in the one-critical state by reducing the pressure so that the extracted ingredients separate from the solvent by precipitation.

The present invention provides an improved method for removing nicotine from a solvent. The nicotine-containing solvent in the supercritical or liquid state is fed to the first end of the retention system comprising one or more containers, each container containing the nicotine retention material, and the substantially nicotine-free solvent is removed from the other end of the retention system. A portion of the used retention material is removed from the first end of the restraint system at regular intervals, while a dose of new retention material is placed at the other end of the restraint system.

The retaining material generally has a certain ability to retain solute, which ability is proportional to the concentration of solute in the solvent received. When the retaining material initially comes into contact with the solute, this material has a high ability to retain solute and is able to remove solute present in small concentrations. When the retaining material becomes saturated with a certain concentration of solute, then the retaining material is able, if the concentration of the solute is increased, to further retain more dissolved material. When new retention material is applied to the other end of the extraction flow system, where the solute concentrations are generally low, the solute concentrations can be further reduced. When a partially saturated retention material is used at the first end of the extraction flow system, this retention material is capable of retaining more solute while reducing the concentration of 3,893,24 solutes in the solvent that has migrated to the other end of the extraction flow system.

The present invention can be used in conjunction with a method for removing nicotine from tobacco. In this case, a substantially nicotine-free, supercritical or liquid solvent is fed to the first tobacco-containing end of the extraction system and the nicotine-rich solvent is removed from the other end of the extraction system. A portion of the extracted tobacco is removed at regular intervals from the first end of the extraction flow system while a portion of the unextracted tobacco is placed at the other end of the extraction flow system.

The ability of a particular solvent to dissolve a solute is generally proportional to the concentration of solute in the extractant being treated. When the pure solvent is initially in contact with the extraction material, it has a high capacity to absorb soluble material and is able to remove soluble substances present in small concentrations. When a solvent saturated with a certain concentration of solute is contacted with an extraction material containing a relatively higher concentration of soluble material, the solvent is able to further dissolve the soluble material. When a partially extracted retaining material is used at the first end of the extraction flow system, where the concentrations of soluble material are generally low, the amount of soluble material remaining in the extraction material can then be further reduced. When a new retaining material is applied to one end of the extraction system, the solvent is further able to remove soluble material from the extraction material while increasing the concentration of solute in the solvent leaving said other end of the extraction flow system.

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The tobacco is extracted as a solvent in either a supercritical or liquid state by continuously passing a substantially nicotine-free solvent to one end of a plurality of extraction vessels connected in series and removing the nicotine-enriched solvent from the opposite end. The nicotine-enriched solvent is then passed through a plurality of series-connected retention vessels to remove nicotine. The nicotine-depleted solvent is then recycled to the extraction vessel or vessels to re-extract the nicotine. Removing or adding an extraction vessel to or from the flow system, or removing or adding a retention vessel from the flow system to provide continuous extraction or retention, respectively, is accomplished by valve settings.

It is an object of the present invention to provide a method for separating nicotine from a solvent which is more efficient than previous methods, which achieves a faster time period and which requires lower investment and operating costs.

Another object of the present invention is to provide a method for separating nicotine from a solvent used for nicotine extraction, which method increases the nicotine load in the nicotine-retaining material and substantially reduces the ratio between the retention material and the tobacco.

These and other objects and advantages of the present invention will become apparent from the following description and appended claims.

In the accompanying drawings

Figure 1 shows an apparatus for semi-continuous extraction of nicotine from tobacco and retention of nicotine from a solvent by a batch process.

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Figure 2 shows an apparatus for the semi-continuous extraction of nicotine from tobacco and the semi-continuous retention of nicotine from a solvent.

Figure 1 shows an apparatus for the semi-continuous extraction of nicotine from tobacco. In the apparatus according to Figure 1, the retention of nicotine from the solvent does not take place according to the invention by semi-continuous retention. Extraction vessels 10 ... 14 may contain tobacco and may be connected in series as part of a flow system with valve settings. According to the figure, the vessels 10 and 11 are in operation and connected to the holding vessel 15. It will be apparent to those skilled in the art that the pump can be placed on any of several lines in the system.

Figure 1 shows the extraction vessels connected in series. It will be apparent to one skilled in the art that many other arrangements are possible and are within the scope of the invention. For example, more or fewer containers may be used in the invention. Multiple lines could be added to the system such that the outlets of each vessel or some vessels are connected multiple times to the inlet of more than one other vessel so that the order of the vessels in the flow system could be changed by changing the valve settings if desired. In this case, the selected containers could be completely isolated from the system for repair or testing. In addition, any vessel connected in series can be replaced by a plurality of vessels connected in parallel, in which case, however, the system would still correspond to the arrangement described.

All extraction vessels are preferably designed for radial or axial flow of solvent. The retaining vessel may have been designed for either radial or axial flow. The radial flow of solvent minimizes the compression of the solid material in the vessel and results in lower pressure losses in each vessel. It will be apparent to those skilled in the art that many flow directions are effective, for example, bottom-to-top or top-to-bottom or radially inward or outward flow in each vessel.

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In a preferred embodiment of the present invention, the extracting solvent is circulated through pump 16 to extraction vessel 10. The pressure in the vessel is controlled by a filling pump (not shown) and the temperature is controlled by heat exchanger 17. The extraction solvent enters through the top of the extraction vessel 10, passes down through the tobacco bed and exits. As it passes through the tobacco layer, the extraction solvent is enriched with nicotine from the tobacco. The solvent is then recycled to the extraction vessel 11, inside which it goes again from the top, runs downwards and leaves the bottom. If the amount of unextracted nicotine in the tobacco contained in the container 11 is greater than the ability of the solvent to receive nicotine, then the solvent is further enriched with nicotine. After the solvent has left the extraction vessel 11, it is recycled to the retention vessel 15. The extraction solvent flows into the vessel from its top and then travels downwards and exits the bottom. As it passes through the container, the nicotine in the solvent is retained on or within the surface of the retaining material. The solvent from which the nicotine has been substantially removed is then recycled by recycling it to the extraction vessel 10.

The extraction vessels 12, 13 and 14 are not in operation but at a standstill to return to operation. During the downtime period, the extraction solvent is removed from the extraction vessel (extraction lines are not shown), the extracted tobacco is removed, the unextracted tobacco is placed in the extraction vessel, and the extraction vessel is refilled with extraction solvent (filling lines not shown). Extraction vessels containing extracted tobacco are periodically removed from the end of the extraction flow system to which the substantially nicotine-free solvent is fed, and at the same time extraction vessels containing unextracted tobacco are added to the end of the extraction flow system from which the nicotine-enriched solvent is removed. Removal of the extraction vessels from and addition to the flow system is accomplished by valve settings.

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Figure 2 shows an alternative preferred embodiment in which a number of extraction vessels connected in series are connected to a plurality of retaining vessels which are also connected in series. It will be clear to a person skilled in the art that other arrangements of detention or extraction vessels are also possible in the manner described above in connection with extraction vessels. The extraction vessels 10 and 11 contain tobacco and are connected in series and operational. The extraction vessels 12, 13 and 14 are not in operation but in a standstill to return to operation. The retaining vessels 20 and 21 are connected in series and are operational. The detent 22 is down for re-operation.

As mentioned above, all extraction vessels are preferably designed for radial or axial flow of solvent. Likewise, all retaining vessels are preferably designed for radial flow or axial flow, but need not be designed in the same way as extraction vessels. Radial flow of solvent minimizes compression of the solid material in the vessel and may result in lower pressure losses in each vessel. It will be apparent to those skilled in the art that many flow directions are effective, for example, in each tank from bottom to top or from top to bottom or radially inward or outward.

As can be seen in Figure 1, the extraction solvent is introduced into the extraction vessel 10 and then recycled to the extraction vessel 11. After leaving the extraction vessel 11, the solvent is recycled to the retention vessel 20. The extraction solvent enters the vessel from its top and runs down and exits the bottom. The solvent is then recycled to the holding vessel, by which time it enters the vessel again from the top, as it travels downwards and exits the bottom. As the solvent passes through vessels 20 and 21, the nicotine in the solvent is retained on or within the surface of the retaining material. The solvent from which the nicotine has been substantially removed is then recycled by recycling it back to the extraction vessel 10.

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The holding container 22 is not in operation but in a standstill to return to operation. During this downtime, the extraction solvent is removed from the retention vessel, the used retention material is removed, new retention material is placed in the vessel, and the vessel is refilled with the extraction solvent. Containers containing spent retention material are removed at regular intervals from the end of the retention flow system to which the nicotine-enriched solvent is fed, and at the same time new retention containers containing retention material are added to the end from which the nicotine-low solvent is removed. Removing or adding retaining vessels from the flow system is accomplished by valve settings.

In yet another embodiment of the present invention, a plurality of series-connected retention vessels may be used to remove nicotine from a solvent by a method using only one extraction vessel instead of a plurality of series-connected extraction vessels.

Numerous extraction solvents capable of dissolving nicotine in both its liquid and gaseous state can be used to reduce the nicotine content of tobacco. In the present invention, the preferred solvent is carbon dioxide in the supercritical state. Examples of other solvents with which the present invention can be carried out include, for example, halogenated hydrocarbons having up to about 4 carbon atoms, such as CFd, CHF3, CClF3, CBrF3 / CFa = CHa, CF3-CFaCF3, CHClFa, CClaFa, CHCl3F, CCl3F, CBrF3 / CFCl = , CH3-CF3, octafluorocyclobutane and hydrocarbons having up to about 5 carbon atoms such as propane, butane, pentane; other useful solvents include NaO, SFe and argon. Mixtures of solvents or additives or co-solvents can be used to achieve better solvent properties.

The solvent in the supercritical state is a 0 59324 y solvent in the gas phase whose temperature is so high that it cannot be liquefied by increasing the pressure. The solvent in the subcritical state is a solvent in the gas phase that can be liquefied by increasing the pressure.

Supercritical carbon dioxide is carbon dioxide having a temperature above its critical temperature, i.e., greater than about 31.3 ° C, and having a pressure greater than its critical pressure, i.e., greater than about 70 atmospheres. Extraction with supercritical carbon dioxide is carried out at a pressure in the range of about 70.. . 1500 atmospheres, and at a temperature higher than said critical temperature and at most about 120 ° C. In the case of the supercritical state of other useful solvents, the corresponding temperature and pressure ranges are generally of the same order of magnitude.

The retaining material in the retention container may be an adsorbent or absorbent having an affinity for nicotine. Adsorbents with which the present invention can be practiced include, for example, activated carbon, silica, alumina, magnesium silicate, and ion exchange resins. This adsorbent can also be mixed with diatomaceous earth in a ratio of up to about 1: 1 to improve the flow rate of the adsorbent. Other useful absorbents include, for example, acid-treated tobacco, tobacco stems and tobacco plant products, and other absorbents such as cocoa bean shells. One particularly useful absorbent is tobacco stems sprayed or moistened with an aqueous solution of polycarboxylic acid or its salts such as monopotassium citrate.

Alternatively, the retaining material in the retention container may be an absorbent having an affinity for nicotine. Absorbent rather than adsorbent agents are used in the invention. Such absorbents include, for example, water, acid, aqueous solutions of acids, and aqueous solutions of salts.

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Preferred acids useful as the retention material in the present invention are non-volatile and solvent insoluble under extraction conditions. Acids that can be used to practice the present invention include, for example, sulfuric, phosphoric, and nitric acids. Other useful acids include polycarboxylic acids such as tartaric acid, citric acid, malic acid, lactic acid, malonic acid, succinic acid, acetic acid and glutaric acid.

Monovalent salts such as the alkali salts of the above-mentioned acids are usually preferred because these salts are less volatile and less soluble in the solvent. The preferred salt of the acid is monopotassium citrate. Monoammonium and diammonium salts of the above acids can also be used. Polyhydric salts of the above acids are also useful, but they are less effective at retaining nicotine.

The extraction process can be carried out with tobacco, which may or may not have been pre-moistened. In general, it is preferred, if necessary, to moisten the tobacco so that the content of volatile substances (UHA) in the oven is at most about 25%. The percentage of volatile substances in the oven (% UHA) in tobacco is a measure of the moisture content and small amounts of other components present and is determined as follows:% UHA = weight loss of the sample over three hours at 100 * C weight of the sample

The vessels required for a semi-continuous system are smaller in size than the vessels required for the batch system, resulting in shorter downtimes required to restore operation. Likewise, the number of containers may be smaller. In addition, the number of CO2 recirculation pumps, the size of the COa storage tanks and the size of the COa treatment system (filling pump, compressor) are smaller. The system requires only one heat exchanger, one art-absorbing condenser S 9 3 2 4 and one dust filter. The average concentration of nicotine in the supercritical COa is higher, resulting in a lower ratio of COa to tobacco and a lower ratio of retaining material to tobacco. In addition, since the system operates semi-continuously, the reliability of the equipment is better and the suitability of the system for the liquid rinsing process is improved.

It is preferred that in the practice embodiments of the present invention, a relatively larger number of smaller vessels be used per mass amount of extractant or retention agent. The figures shown illustrate the use of two series-connected extraction or retention vessels in a flow system at any time, but three or more series-connected vessels can also be used in a process flow system to achieve relatively more efficient extraction or retention, with relatively higher costs for materials and plant physical equipment.

It is preferred that the extraction and retention vessels be substantially filled with tobacco or retention material, although the invention may also be practiced with containers that are less than substantially filled. The amount of solvent used is preferably so large that the system can be used under supercritical conditions. If liquid solvents are used in the system, then the amount of solvent used is preferably sufficient to completely wet the tobacco and retention material, with the amount of solvent preferably being large enough to fill substantially all of the vessels in the flow system. It is preferred that the total volume of solvent be selected so that the concentration of nicotine in the solvent leaving the last extraction vessel of the flow system is as high as possible, which volume generally corresponds to the smallest possible amount of solvent. The use of the smallest possible amount of solvent generally minimizes the extraction of flavor-producing components from the tobacco, thereby improving the quality of the 12,893,424 extracted tobacco. It will be apparent to one skilled in the art of extraction that a reasonable variation in these design criteria is possible and is within the scope of the present invention.

The choice of solvent flows and vessel dimensions depend on each other. The most basic quality parameter in the process of the present invention is "M / M", i.e. the total mass of solvent that has passed through the tobacco during the extraction period divided by the mass of the extracted tobacco. The solvent flow should be sufficient to extract nicotine satisfactorily from the tobacco within a reasonable time. Once the target time and the final nicotine concentration are known, one skilled in the art can calculate or determine the required volume of the vessel by simple experiments. The extraction time can then be adjusted to achieve the desired, exact amount of nicotine extraction. M / M values of 75: 1 to 300: 1 lead to satisfactory results.

Excessive solvent speed can lead to bed compression and poor system performance. The flow of solvent down through the tobacco bed can occur at speeds that are preferably less than about 0.1 to 2 feet (about 0.03 to 0.6 m) per minute, and more preferably 0.5 to 1 foot (about .0, 15... 0, 30 m) per minute. Correspondingly, a larger container diameter can be used to reduce the rate of solvent necessary to achieve a given flow rate, while a relatively smaller diameter can be used to increase the amount of solvent in contact with each tobacco particle per unit time. The height or length of the container is preferably about 1.. . 5 times, more preferably 1.. . 2 times the diameter of the container.

The amount of retention material should preferably be such that it is sufficient to retain substantially all of the nicotine extracted from the tobacco. With a few simple experimental arrangements, it is possible to quickly find out what amount is used in a particular flow arrangement. For example, when a solid retention material is used, the amount of nicotine adsorbed from the retained retention material after the retention period that is adsorbed at different distances from the inlet of the retention vessel can be analyzed. Alternatively, the concentration of nicotine in the solvent at the outlet of the retention system can be determined by extracting repeated nicotine charges. When the nicotine concentration increases significantly, the retaining material is substantially saturated. However, it should be noted that this same retaining material may still be able to remove nicotine if higher concentrations of nicotine are introduced into the retention vessel with the process stream.

In a typical semi-continuous extraction and retention system, as shown in Figure 2, in the case of an extraction vessel, the period length is 1 hour in the first extraction vessel and 1 hour in the second extraction vessel when the total extraction time of the tobacco placed in each extraction vessel is 2 hours. The time available for the extraction vessel to stand is 3 hours. In the case of retention vessels, the length of the period is 3 hours in the first vessel and 3 hours in the second vessel, so that the total retention time of the adsorbent or absorbent material charge in each holding vessel is 6 hours. The length of time available for detention outage is 3 hours.

When a container containing tobacco is extracted with a stream of solvent, the concentration of nicotine at the outlet of the container is initially high, decreasing over time at an exponential rate of first order. In a batch system in which a single vessel is extracted until a satisfactory level of nicotine is reached, the average concentration of nicotine at the outlet per unit time is relatively higher in the early stages of extraction and relatively lower in the later moments. If two or more vessels connected in series are extracted, the behavior corresponding to the concentration / unit of time ratio is similar, but each time a vessel containing new tobacco is added to the flow system according to the present invention 14 89 324, the nicotine concentration at the outlet of the last extraction vessel increases. The low concentrations observed in the late stages of batch extraction are not reached in the solvent leaving the last extraction vessel as long as new tobacco is repeatedly introduced into the extraction system. However, the nicotine concentration at the outlet of the first extraction vessel drops to a low level in the same way as in the batch process but in a somewhat shorter time, the other conditions being the same. The average concentration of nicotine in the effluent is on average higher than in the batch extraction.

Table 1 compares the nicotine concentration in the supercritical carbon dioxide leaving the extraction flow system during batch extraction with the corresponding concentration in the semi-continuous extraction. The table shows the amount of nicotine removed from tobacco in dry weight (kp) at 0, 1, and 2 hours. The average total nicotine concentration in carbon dioxide is lower in batch extraction compared to semi-continuous extraction, with corresponding values of 120 ppm and 214 ppm. Because the average nicotine concentration is higher, the retention process is relatively more efficient and a total of less CO 2 (M / M is 84: 1 and 150: 1, respectively) must be passed through the semi-continuous system to achieve the corresponding nicotine removal.

table 1

Comparison of batch extraction and semi-continuous extraction

Extraction Nicotine Removed Nicotine pit.

time in tobacco in nicotine CO2 (ppm) (h) (%) amount (kp) (average / h) _ (g / 100 g tobacco) Contribution Semi-continuous 0 100 0 1, 0 13, 2 1, 605 (86 .8%) 214 214 2.0 2.7 0, 195 (10, 5%) 2 ± 214 1.80 (97.2%) 120 214 (total) (average) is 39324

Table 2 compares the ratio of carbon to tobacco on a dry weight basis (kp) when both extraction and retention are performed by the batch method, extraction is performed by the batch method and retention by the semi-continuous method, or when both extraction and retention are performed by the semi-continuous method, COa / tobacco (M / M) while remaining constant. The methods of Examples 1 and 2 were used in this study. The carbon / tobacco ratio fell from 4 in the case of batch extraction and retention to 2 (excluding the start-up period) in semi-continuous retention, which means a 50% reduction in the carbon required. When semi-continuous extraction is combined with semi-continuous retention, the nicotine content entering the retention vessel is on average higher and the retention is more efficient, so even less carbon is needed. The estimated carbon / tobacco ratio for semi-continuous extraction and retention is significantly less than 2.0 (range 0.4 to 0.8), which means that even if the calculation is based on a value of 0.8, the 80% reduction in carbon required for batch extraction and 60% reduction in carbon compared to semi-continuous extraction.

Table 2

Carbon / tobacco ratio (kp) _

Batch extraction / withholding 4

Batch Extraction / Semi-Continuous Retention 2 (Effective)

Semi - continuous extraction / semi - continuous retention under 21

Planned relationship; it is estimated to be in practice in the range 0, 4.. . 0, 8.

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Table 3 compares the different features of batch extraction and semi-continuous extraction and retention. Fully flavored tobacco with a nicotine content of 1.85% (kp) and an oven volatiles content of 25% is extracted with carbon dioxide under supercritical conditions, i.e. at 260 atmospheres and 70 ° C, using carbon as a retention material. After extraction, the nicotine content in the tobacco is 0.05%, which corresponds to a reduction of 97%.

The batch extraction system according to Table 3 consists of four full-scale extraction units, each consisting of one extraction vessel and two retaining vessels connected in series. The results are the same when four batches are passed through a single large unit except that the solvent flow must be limited to avoid compression of the tobacco bed and that a longer time is required to extract the same total volume of tobacco. The system based on semi-continuous extraction and retention is essentially as shown in Figure 2, and the volume of the containers included in this system is selected to handle the same amount of tobacco as in the batch process. The flow rate of COa is chosen to be approximately the same in both examples, while the required M / M depends on the configuration of the vessels (see Table 1 and the discussion above). In each configuration, 3634 pounds (approximately 1648 kg) of tobacco is processed per hour. The nicotine load of carbon is expressed as a percentage of nicotine per unit weight of carbon at the end of the extraction.

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Table 3

Batch Extraction / Semi-Continuous Semi-Continuous Extraction and Retention Retention (4 units) (4 units, respectively)

Period length 5 h 1 h extraction 3 h adsorption

Extraction time 2 h 2 h

Downtime 3 h 3 h

Ratio MCC> 2 / Mtup. 1,150 84

Carbon / tobacco ratio 22 52 (0.8) 3 CO2 ~ flow 0.341 M lbs / h4 total (approx. 0.155 Mkg / h) 0.305 M lbs / h per unit (approx. 0, 138 Mkg / h) den or tot.

1, 364 M lbs / h (approx. 0.619 Mkg / h) in 4 units

extraction vessel:

Number of dishes 4 5

Tobacco input, total , lbs. (kp) 18168 18168 (kg) (8240) (8240)

Stake per container, lbs. (kp) 4542 3634 (kg) (2060) (1648)

Tobacco volume / container, ft3 458 366 (m3) (12, 97) (10, 36)

Nominal capacity of the vessel, ft3 800 640 (m3) (22, 65) (18, 12)

Detention containers:

Number of dishes 8 3

Total carbon input, lbs. 72672 <65000 (26240) (kg) (32963) (<29484) (11902)

Carbon cartridge / container, lbs. 9084 <21870 (8748) (kg) (4120) (<9920) (3968)

Carbon v / v, ft3 364 <875 (350) (m3) (10.30) (<24.8) (9.91)

Nominal volume of the vessel, ft3 804 1500 (617) (m3) (22, 77) (42, 48) (17, 47) 1. B 9 3 2 4

Ni my home:

Load on carbon,% 0.9> 0.9 (2.25)

Amount left, lbs. / charge 328 65.6 (kg / charge) (149) (29.8) CO 2 flow (M lbs. / h) 1, 364 0, 305 (Mkg / h) (0.619) (0.138)

Nicot, mean. pit.

In COa (ppm) 120 214

Relationship Mcoa / Mtup. 1,150 84

Total number of pressurized containers 12 8 1 MC02 / Mtup. = Mass of C0a / mass of tobacco 2 Effective ratio 3 A ratio of 2 is the worst case, with an expected value of 0.8 or better.

Λ M lbs / h = million pounds per hour (Mkg / h = million kg / h).

The following examples are intended to illustrate the application of the present invention and its advantages.

Example 1

Batch Extraction / Batch Retention This example illustrates the old technology to better illustrate the advantages of the present invention.

The American tobacco blend, bp 5, 5 kg, was moistened in a rotating cylinder by spraying water to give a UHA content of 25%. The moistened tobacco was placed in an extraction vessel. 22 kg of activated carbon was placed in a holding vessel. The system was pressurized with CO 2 to a pressure of 260 bar and a temperature of 70 ° C. The CO 2 flow from the tobacco extraction vessel to the carbon containment vessel was maintained for 60 minutes. The CO 2 was then introduced into the atmosphere and the tobacco and carbon were removed from their vessels. The nicotine content profile of the carbon contained in the retention vessel showed that all the carbon was needed to retain the nicotine, i.e., nicotine was present in a low concentration at the outlet of the adsorption device. About 97% of nicotine was removed from tobacco. The driving details were:

Tobacco weight: 5, 5 kg (pcs)

Carbon weight: 22 kg

Carbon / tobacco ratio: 4/1 CC> 2 flow: 1, 1 m3 / h MCOa / Mtobacco: 150

Example 2

Batch extraction / semi-continuous retention

The semi-continuous retention of nicotine was performed as follows: The American tobacco blend, 5.5 kg kp, was moistened in a rotating cylinder by spraying water to give a UHA content of 25%. The moistened tobacco was placed in an extraction vessel. 11 kg of activated carbon were placed in each of two retention vessels (adsorption vessels). The system was pressurized to 260 bar and 70 ° C with CO 2. The flow of CO 2a from the tobacco to one holding vessel was maintained for 30 minutes, after which it was directed to the other holding vessel for a further 30 minutes. The total extraction time was 1.0 hours. At the end of the extraction, the CO 2 was introduced into the atmosphere and the carbon in the adsorption vessel 1 was replaced with a new batch of activated carbon. A new batch of tobacco was placed in the extraction vessel, but the carbon in the adsorption vessel 2 was stored for reuse. Supercritical CO2 at a pressure of 260 bar and a temperature of 70 ° C was circulated through a new batch of tobacco and adsorption vessel 2 for 30 minutes and then through adsorption vessel 1 for a further 30 minutes. This measure, which mimics continuous detention, was continued for six new batches of tobacco. For each tobacco batch, the nicotine extraction was 96.5% or better.

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The driving details were:

Tobacco weight: 5, 5 kg (pcs)

Carbon weight: 22 kg in total, 11 kg per container

Carbon / tobacco ratio: 2/1 (effective) CO 2 flow: 1, 1 m3 / h ”C02 /" tobacco: 150

Tobacco Extraction Time (min) Nicotine

Driving_weight (kg kp) Ads 1 Ads 2 Total exit (5) 1 5, 5 30 30 60 97, 2 2 5, 5 30 30 60 96, 5 3 5,5 30 30 60 97,0 4 5, 5 30 30 60 97, 7 5 5, 5 30 30 60 97, 0 6 5, 5 30 30 60 97, 2

Note: The carbon in the second adsorption vessel was used as the first adsorbent in the next batch.

Example 3

Semi-continuous extraction / semi-continuous retention The following example is illustrative.

Eight pressure vessels are arranged according to Figure 2 for series extraction. The extraction vessels (10 ... 14) are so large that each can hold 4845 lbs. (approximately 2198 kg) of tobacco, with a UHA content of 25% (i.e., 366 cubic feet (approximately 10.36 m3) of tobacco). The holding containers (20 ... 22) are large enough to hold 21870 lbs each. (approx. 9920 kg) of activated carbon (i.e. the concentration of activated carbon is 875 cubic feet (approx. 24.8 m3)).

Dry carbon (8748 lbs. (Ca. 3968 kg)) is placed in each holding vessel (20, 21, 22). The full-aroma American tobacco blend is moistened by spraying directly ion-2i 89324 exchanged water in a rotating cylinder so that the UHA content increases from 12% to 25%. About 4845 lbs. (ca. 2198 kg) pre-moistened tobacco (i.e. 3634 lbs. (ca. 1648 kg) kp) is placed in each extraction vessel (10, 11, 12, 13, 14).

Start

A COa filling pump is used to pressurize vessels 10 and 20. Carbon dioxide is recycled through the flow system at a rate of 611,000 lbs./hour (about 277,145 kg / h). After the extraction conditions, i.e. 260 bar and 70 ° C, have been reached, the circulation of CO 2 is continued through vessels 10 and 20 for one hour. Vessels 11 and 21 are pressurized with CO 2 during this first hour.

During the second extraction hour, the CO 2 flow is directed through vessels 10, 11, 20 and 21 as shown in Figure 2. Vessel 12 is pressurized with CO2 during this second hour.

During the third hour of operation, the extraction vessel 10 is removed from the flow system and the vessel 12 is added to the flow system. The CO 2 flow is directed through vessels 11, 12, 20 and 21. Vessel 22 is pressurized with CO2 during this third hour and vessel 10 begins to shut down. During the downtime, the CO2 in the extraction vessel 10 is vented to the atmosphere and the extracted tobacco is removed. The vessel 10 is again filled with tobacco and then with pressurized CO2, after which the vessel is ready to be returned to the extraction cycle. Three hours are available for extractor downtime.

During the fourth hour of operation, vessel 13 is added to the extraction cycle and vessel 11 is removed from the extraction cycle. The retaining vessel 20 is removed from the flow system and the vessel 22 is added to the flow system. The CC> 2 flow is directed through vessels 12, 13, 21 and 22. During the downtime, the CO2 in the capture vessel 20 is vented to the atmosphere and the spent carbon is removed. The vessel 20 is refilled with carbon and then filled with pressurized CO2, after which it is ready to be returned to the extraction cycle. Three hours are available for the container to be shut down.

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Conditions that remain unchanged are reached within six hours. Vessel 10 is returned to the extraction cycle within 6 hours of operation (Table 4). Each of the extraction vessels 11, 12, 13 and 14 is stopped in the same manner and then returned to the extraction cycle.

Continuous activity

As shown in Figure 2 and Table 4, once an hour, one batch (4845 lbs. (Ca. 2198 kg)) of extracted tobacco is produced. The nicotine content in tobacco has decreased by 97%, from 1.85% nicotine (kp) to 0.05% nicotine (kp). The extraction time is a total of two hours. The ratio of solvent to tobacco is 84 parts COa per part tobacco (kp). This ratio of solvent to tobacco is significantly lower than the ratio required in the batch system, 150 parts COa per part (kp) of tobacco.

23 B S 3 2 4

Table 4 COa flow arrangement1 Stoppage -

In the Extraction-Retention phase

Time dishes dishes are _ (h) __ dishes2_ Start: 1 10 20 2 10.11 20.21 3 11, 12 20, 21 10 4 12, 13 21, 22 10, 1 1, 20 5 13.14 21, 22 10 , 1 1, 12, 20 6 14, 10 21, 22 11, 12, 13, 20

Continuous operation under steady state conditions: 7 10, 11 22, 20 12, 13, 14, 21 8 11, 12 22, 20 13, 14, 10, 21 9 12, 13 22, 20 14, 10, 11, 21 10 13, 14 20, 21 10, 11, 12, 22 11 14, 10 20, 21 11, 12, 13, 22 12 10, 11 20, 21 12, 13, 14, 22 13 11, 12 21, 22 13, 14 10, 20 14 12, 13 21, 22 14, 10, 11, 20 15 ----- continuous operation -------------

Note: 1 The COa flow is maintained at 305,000 lbs / h (approx. 138,345 kg / h) through these vessels.

2 The length of the downtime is 3 hours. During downtime, the following steps are performed: CO is discharged from the vessel

The extracted tobacco or used carbon is removed from the container

New tobacco or activated carbon is placed in the vessel. The vessel is pressurized with CO 2 under extraction conditions (260 atm, 70 ° C).

24 S 9 3 2 4

As can be seen from Table 5, continuous action increases the concentration of nicotine in the COa solvent without significantly increasing the concentration of other soluble materials present in the tobacco (which are considered important for product quality) in the COa solvent.

Table 5

Contribution- Continuous operation nta_action nta% nicotine in tobacco (%, kp)

Extractable 1.85 1.85

Extracted 0.05 0.05

Solvent / tobacco ratio (kp) 150 84

Soluble matter content in CO2 (ppm)

Nicotine 120 214

Other soluble tobacco substances 120-240 120-240

% Of solutes removed from tobacco

Nicotine 1.8 1.8

Other solutes 1, 8-3, 6 1.0-2.0

Expert judgment suggests that the subjective quality of cigarettes made from tobacco extracted using a low ratio of solvent to tobacco is better than the subjective quality of cigarettes made from tobacco extracted using a high ratio of solvent to tobacco.

Claims (15)

25 89324 A method of separating nicotine from a solvent, the method comprising feeding a nicotine-containing solvent to a first end of a restraining flow system containing a nicotine-retaining material and removing a substantially nicotine-free solvent from one end of the restraining flow system, characterized in that a batch of used restraining material is periodically end and a batch of fresh retaining material is periodically placed at one end of the retaining flow system. A method according to claim 1, characterized in that the retaining material is an absorbent selected from the group consisting of carbon, silica, alumina, magnesium silicate and ion exchange resins. A method according to claim 1, characterized in that the retaining material is selected from tobacco products treated with an acid or a salt thereof, such as tobacco, tobacco stems and tobacco plant products, and cocoa bean shells. A method according to claim 1, characterized in that the retaining material is an absorbent selected from the group consisting of water, acid, aqueous acid solution and aqueous salt solution. Process according to one of the preceding claims, characterized in that the retaining material contains an absorbent selected from sulfuric acid, phosphoric acid, nitric acid, tartaric acid, citric acid, malic acid, lactic acid, malonic acid, succinic acid, acetic acid, glutamic acid or monocalamic acid. 26 S9324 Method according to one of the preceding claims, characterized in that the retention process is carried out in a plurality of retention vessels connected in series. Method according to Claim 6, characterized in that two or more holding vessels connected in parallel are used in each case instead of one or more vessels connected in series. Process according to Claim 1, characterized in that the solvent is in a supercritical state. Process according to Claim 1, characterized in that the solvent is in a liquid state. A method according to claim 8 or 9, characterized in that at least one retaining vessel is periodically removed from said first end of the retaining flow system and at least one second retaining vessel is added to said second end of such a system. Apparatus for carrying out the method according to claim 1, characterized in that it has a plurality of retaining vessels (20 ... 22) which are connected in series and adapted to receive a solvent in a supercritical state. Apparatus according to Claim 11, characterized in that two or more vessels connected in parallel are used in each case instead of one or more vessels connected in series. Apparatus according to claim 11, characterized in that it comprises a plurality of retaining vessels (20 ... 22) connected in series and containing a retaining material to form a restraining flow system, the system having a first end and a second end such that the nicotine-containing solvent can be fed to said first end retention vessel and removed as substantially nicotine-free solvent from said second end retention vessel, the device further comprising at least one second retention vessel containing nicotine-free retention material, the container being periodically to said second end of the flow system when at least one used retaining vessel is removed from said first end. Use of a method according to claim 1 for recovering nicotine from a nicotine-containing solvent used to extract nicotine from tobacco. Use according to claim 14, characterized in that the nicotine-containing solvent is used for extracting nicotine from tobacco in an extraction flow system, wherein a batch of extracted tobacco is periodically removed from the first end of the extraction flow system and a batch of unextracted tobacco is placed at the other end of the extraction flow system. 28 0 9 324