WO2016145892A1

WO2016145892A1 - Cut-tobacco expansion process which reduces medium loss

Info

Publication number: WO2016145892A1
Application number: PCT/CN2015/094778
Authority: WO
Inventors: 彭黔荣; 蔡元青; 张文; 成清校; 惠建权; 邓葵; 任宏杰; 满鸣; 熊灿普; 杨继志; 张华�; 马玉坤; 于丽君; 路兰卿
Original assignee: 贵州中烟工业有限责任公司; 北京航天试验技术研究所
Priority date: 2015-03-18
Filing date: 2015-11-17
Publication date: 2016-09-22
Also published as: CN106031525A

Abstract

Provided is a cut-tobacco expansion process which reduces medium loss, comprising the steps: (1) impregnation: impregnating cut tobacco in a medium to form impregnated tobacco; (2) medium recovery: recovering liquid and gaseous medium after impregnation; (3) delivery: after impregnated tobacco is loosened, delivering fixed quantity thereof to tobacco expansion device (300) by means of vibration; at the same time, heating the surface of the impregnated tobacco, causing the liquid medium on the surface of the impregnated tobacco to evaporate; (4) expansion: heating the impregnated tobacco in the tobacco expansion device (300), causing the liquid medium inside the impregnated tobacco to evaporate and result in expanded tobacco; (5) secondary recovery of medium: recovering the gaseous medium evaporated in step (3) and/or step (4), and compressing and condensing the gaseous medium, then storing same. In the cut-tobacco expansion process, the gaseous medium evaporated during delivery and/or expansion of the impregnated tobacco is compressed and recovered, greatly reducing the loss caused by the vaporization of the impregnated medium in the cut tobacco; thus the medium is repeatedly recycled, solving the problem of the high cost of the large amount of medium used in a cut-tobacco expansion system.

Description

Expansion process of cut tobacco for reducing dielectric loss

Technical field

The invention relates to a tobacco shuffing process, in particular to an expansion process of shredded tobacco which reduces medium loss.

Background technique

Tobacco expansion technology has always been one of the important research areas of the tobacco industry. Because the expanded tobacco technology has obvious economic and social benefits, the tobacco industry attaches great importance to this technology, so that it can be quickly promoted and applied.

The invention is directed to a novel environment-friendly tobacco expansion device. The device utilizes the physical properties of an expansion medium (hereinafter referred to as "medium") to impregnate the tobacco under a certain temperature, pressure, time and other comprehensive process conditions, so as to expand the medium. Immersed in tobacco cells, the impregnated shredded tobacco is transported to the microwave expander through a closed system. In the microwave resonant cavity, the water molecules in the shredded tobacco sharply rub, and the heat generated by the collision causes the expansion agent in the tobacco to evaporate, pushing the tobacco cell wall to expand outward. Thereby the tobacco is expanded and the medium is recycled for recycling.

The expansion medium used in this equipment is the self-developed KC-2A environmental expansion medium, which has zero ozone depletion potential (ODP), good permeability, compatibility, stability and safety of the medium. The expanded tobacco has Physical properties such as higher filling value, higher filament ratio, better sensory quality and better compatibility can meet the needs of tobacco expansion process and meet the long-term development requirements of the national tobacco industry.

However, the expansion medium has a low boiling point, a boiling point of about 15°, and is extremely volatile under normal temperature conditions, and the loss of the medium accounts for about 80% of the operating cost due to the high cost of the medium, which limits the operation and market promotion of the equipment.

Therefore, the present invention contemplates the use of a vacuum compression recovery method to recover the vaporized medium in the process after the tobacco is immersed in the can, thereby reducing the loss of the medium during the production process and reducing the production cost.

Summary of the invention

The object of the present invention is to overcome the deficiencies of the prior art described above, and to provide a shredded tobacco dip expansion process for recovering a medium vaporized by impregnating shredded tobacco during the processing after impregnation. The basic idea of adopting the technical solution of the present invention is:

1. A tobacco expansion process for reducing dielectric loss, comprising the steps of:

(1) impregnation: impregnating the shredded tobacco in a medium to form impregnated shredded tobacco;

(2) Medium recovery: recovery of liquid and gaseous medium in the impregnation equipment;

(3) Transportation: After the impregnated tobacco is loosely processed, it is sent to the tobacco expansion device by vibration quantitatively, and the surface of the impregnated tobacco is heated to evaporate and vaporize the liquid medium on the surface of the impregnated tobacco;

(4) Expansion: heating the impregnated tobacco in the tobacco expansion device to evaporate and vaporize the liquid medium inside the impregnated tobacco to obtain expanded tobacco; the characteristic is:

(5) Secondary recovery of the medium: recovering the gaseous medium evaporated in the steps (3) and/or (4), and compressing and condensing the gaseous medium into a liquid state and storing.

Step (3) recovering the gaseous medium in a vacuum environment with a pressure of 20 kPa to 50 kPa.

Step (4) recovers the gaseous medium in a vacuum environment with a pressure of 20 kPa to 50 kPa.

Step (5) recovering the gaseous medium is recovered by compressor negative pressure, and the compressor pressure is 700 kPa-1500 kPa.

The compression in the step (5) comprises partially compressing the gaseous medium into a liquid medium in the compressor, and the compressor pressure is 700 kPa to 1500 kPa.

The condensing in the step (5) comprises cooling the compressed gaseous and liquid medium in a water-cooled condenser to condense the gaseous medium into a liquid medium, and the condensed water temperature is 10°-15°.

The purifying in the step (5) comprises stratifying the condensed liquid medium, extracting the liquid medium and discharging the non-condensable gas.

The step (5) of storing comprises feeding the purified liquid medium into a medium storage tank for storage.

Step (4) The expansion process is performed by microwave heating, and the microwave source is 20 Kw, and the frequency is 915 MHz. Microwave tube.

The medium recovered in the step (2) and the step (5) is used for the step (1) impregnated tobacco to be recycled.

After adopting the above technical scheme, the recycling and recycling of the flue gas vaporization medium after immersion is realized, the use loss of the expansion medium is greatly reduced, and the problem of large dielectric loss is successfully solved.

The specific embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

DRAWINGS

1 is a flow chart of a tobacco shuffling process for reducing dielectric loss of the present invention

Figure 2 is a schematic view of an embodiment of the present invention

3 is a schematic diagram of a transmission device in an embodiment of the present invention;

4 is a schematic view of a microwave expansion device in an embodiment of the present invention;

Figure 5 is a left side view of the wave expansion device in the embodiment of the present invention

6 is a schematic view showing the connection of a transmission device and a tobacco expansion device in an embodiment of the present invention;

Figure 7 is another embodiment of the present invention

Figure 8 is another embodiment of the present invention

Immersion tank 100, conveying apparatus 200, tobacco expansion apparatus 300, exhaust pipe 4, vacuum compressor 5, secondary medium recovery pipe 6, condenser 61, pressurized medium storage tank 62, medium recovery pipe 7, medium buffer tank 71 , hot condensation tank 72, condensation tank 73, medium spray pipe 8, heat medium recovery pipe 9, medium storage tank 10, rotary valve 11, medium metering tank 12, gaseous medium recovery pipe 13, upper chamber 210, lower chamber Room 220, looser 230, exhaust port 211, tobacco storage bin 222, vibration groove 223, conveyor belt 224, heater 225, expansion chamber 310, observation window 311, illumination lamp 312, microwave heating chamber 321, and microwave radiation port 322, microwave delivery tube 323, microwave source 324, operating window 325, conveyor belt 330, exhaust port 301, expansion chamber inlet 302, and expansion chamber outlet 303.

detailed description

After the impregnation of the tobacco shredded tobacco in the prior art is completed, the medium in the impregnation apparatus is recovered. The impregnated shredded tobacco enters the conveying device, and after being scattered and vibrated by the conveying device, it enters the microwave heating device, and the heating in the microwave device causes the medium impregnated inside the shredded tobacco to expand and vaporize, so that the volume of the shredded tobacco is increased to achieve the effect of expanding the shredded tobacco. However, the surface of the shredded tobacco is covered with a medium, and the inside of the shredded tobacco is also filled with an expansion medium. The medium which is wetted on the surface of the tobacco during the transfer process vaporizes and volatilizes a part of the medium, and is immersed in the surface of the tobacco surface in the microwave expansion device and is immersed in The medium inside the cut tobacco will all evaporate and vaporize. After the medium is vaporized, it will be completely lost into the air and will not be recycled. A large amount of waste of the medium is caused, the amount of the expansion medium is greatly increased, the price of the expansion medium is high, and the cost of the production of the tobacco is greatly increased, causing tremendous pressure.

As shown in Fig. 1, the present invention contemplates adding step (5) secondary recovery of the medium: recovering the gaseous medium evaporated in steps (3) and/or (4), and compressing and condensing the gaseous medium into a liquid state for storage.

Specifically, the vaporized medium gas is recovered in the conveying section and the expanding section of the impregnated shredded tobacco, and an exhaust pipe 4 and a negative pressure device are added to the conveying apparatus 200 and the tobacco expanding apparatus 300 for pumping.

The conveying device 200 and the tobacco expanding device 300 must be sealed in consideration of the recycling effect to ensure the purity of the recovery, and to avoid air incorporation as much as possible. The lower the pressure, the easier the gaseous medium will diffuse to facilitate recovery. Taking into account the actual production situation, set the evacuation pressure to 20kPa-50kPa. Therefore, steps (3) and (4) recover the gaseous medium in a vacuum environment with a pressure of 20 kPa to 50 kPa.

Preferred embodiment:

As shown in FIG. 2, an embodiment of the present invention comprises a tobacco infusion expansion system, comprising a conveying device 200, an upper portion of the conveying device 200 is provided with an impregnation tank 100, and a lower end of the conveying device 200 is connected with the tobacco expansion device 300, the impregnation The lower portion of the tank 100 is connected to the medium storage tank 10 through a medium recovery pipe 7, the top of which is connected to the medium storage tank 10 via a medium spray pipe 8, characterized in that the conveying device 200 and/or the tobacco expansion device 300 The suction pipe 4 is connected to a negative pressure device, and the negative pressure device outlet is connected to the medium storage tank 10 through the secondary medium recovery pipe 6.

Specifically, the vacuum device is a vacuum compressor 5, the purpose of which is to generate a negative pressure and compress the extracted gaseous medium to cause the gaseous medium to condense into a liquid medium at a higher temperature.

Regarding the selection of the compression power of the vacuum compressor 5, it is necessary to consider the main cause of the dielectric loss. The loss of the tobacco expansion medium is related to the amount of air entering the system and the saturated vapor pressure of the medium itself.

In order to calculate the amount of dielectric loss during the compression process, it is necessary to first determine the amount of air entering the system's confined space. There are two cases for calculating the amount of air permit. One is the amount of air entering the closed system in a single working cycle after multiple cycles of the system; the other is entering the air in the cold closed circuit during the first working cycle of the system. the amount. The calculation of the former case is small, conservative, and calculated in the latter case.

The sealing space in the conveying equipment and the tobacco expansion equipment must be guaranteed to be between 20 kPa and 50 kPa, and the amount of air that can enter the closed system has two parts:

(1) The air remaining in the system's confined space after being evacuated. The total space of the closed equipment is calculated as 50m ³ , and the air volume is estimated to be 50×0.2×1.205=12.05kg according to the evacuation pressure of 20kPa.

(2) Air that leaks into the equipment from the static and dynamic seals of the enclosed equipment. The empirical relationship between volume and leakage of the vacuum system is given in Table 19-38 of the Chemical Process Design Manual - Volume, as follows:

According to the table, the total space of the closed equipment is 50m ³ , and the corresponding air leakage is about 5~10kg/h. Considering the leakage of the connecting section and the pipeline, the total leakage in the working cycle of 1h is 7.95kg. For a single batch of expanded tobacco, the total amount of air is estimated to be 12.05 + 7.95 = 20 kg.

The condensation temperature is calculated at 14 ° C, and the saturated vapor pressure of the corresponding medium is 98 kPa, that is, the partial pressure of the medium is 98 kPa. The discharge of the medium is calculated according to the total amount of air, the saturated vapor pressure and the compression pressure. If the compression pressure is: P, the partial pressure of the air is: P-98 kPa. Since the van der Waals constant and the virial coefficient of the medium vapor are difficult to obtain, but the pressure is not In the high case, the calculation is based on the ideal gas, and the error is limited. Therefore, according to the ideal gas state equation:

Compression pressure 0.7MPa (700kPa)

The amount of medium in the vent gas is

Compression pressure 1.0MPa (1000kPa)

The amount of medium in the vent gas is

Compression pressure 1.5MPa (1500kPa)

The amount of medium in the vent gas is

From the above calculation results, when the compression pressure is 0.7MPa, the dielectric loss of the 300kg expanded tobacco produced in a single batch is 15.04kg, compared with the original 112kg, the percentage of medium consumption is reduced from 37.2% to 5.0%. Significantly, if the compression pressure is increased, the dielectric loss The amount will be lower. However, considering the performance of the vacuum compressor 5 and the economics of the equipment, it is reasonable to set the compression force to 0.7 MPa. Considering the actual situation, it can be selected in the interval of 700kPa-1500kPa.

Therefore, the recovery of the gaseous medium in step (5) is carried out by the negative pressure of the compressor, and the compressor pressure is 700 kPa to 1500 kPa.

Specifically, a condenser 61 is provided on the secondary medium recovery pipe 6 connected to the outlet of the vacuum compressor 5. The purpose is that the gaseous medium compressed by the compressor is partially condensed into a liquid state but a part of the gaseous medium is still present and condensed, and the specific condenser 61 is water-cooled, and the water temperature is 10-15°, because the vacuum compressor 5 provides The pressure, so that the entire medium can be condensed into a liquid state without a very low temperature, but at this time the liquid medium is mixed with some non-condensable gas and condensed water to be further processed.

Specifically, a pressurized medium storage tank 62 is provided in a portion where the secondary medium recovery pipe 6 is located between the condenser 61 and the medium storage tank 10. The purpose is that, after the condensed liquid medium is mixed with non-condensable gas and condensed water, the condensed liquid medium is allowed to stand in the pressurized medium storage tank 62, the liquid medium is in the lower layer, and the condensed water is in the middle layer, The condensed gas is in the upper layer, and the condensed water and the non-condensable gas are discharged to obtain a purified liquid medium. The liquid medium is sent to the medium storage tank 10 through the secondary medium recovery pipe 6 for recycling.

In order to achieve a better gaseous medium recovery effect, the gaseous medium recovery process requires as little air and impurity as possible, and the transmission device and the tobacco expansion device 300 need to be optimally set. Sealing is performed at the junction of the conveying device 200 and the dip tank 100, and a seamless seal is provided at the joint between the upper and lower chambers of the conveying device 200. A heater 225 is added to the conveying device 200. The expansion chamber 310 is provided for the microwave expansion device, and the conveying device 200 and the expansion chamber 310 and the connecting portion thereof are sealed to minimize the mixing of air, and the negative pressure is used to improve the recovery effect of the gaseous medium.

Specifically, the transport apparatus 200 as shown in FIG. 3 includes an upper chamber 210 and a lower chamber 220, and the upper chamber 210 and the lower chamber 220 are seamlessly sealed by a looser 230. The purpose of the seamless seal connection is to prevent air ingress and loss of gaseous media. The purpose of providing the upper chamber 210 is that the shredded tobacco is impregnated from the impregnation tank 100 after being impregnated, and the tobacco is dense and compact in a dough shape due to the pressure inside the impregnation tank 100. If the microwave expansion treatment is directly performed, The tobacco shreds will be unevenly heated and will stick to each other and affect the expansion effect. At the same time, the medium is not sufficiently heated to evaporate insufficiently, which also causes some residual unvaporized medium to enter the subsequent process, resulting in waste of medium loss. Therefore, after the impregnated tobacco is discharged out of the can, it is loosely treated.

Specifically, as shown in FIG. 3, the lower chamber 220 is provided with a tobacco storage cabinet 222. The tobacco storage tank 222 is provided with a vibration groove 223. The vibration groove 223 is provided with a conveyor belt 224. A heater 225 is also provided in the chamber 220. The purpose is that the loosely processed tobacco enters the microwave expansion device, and if the amount of entry is too large, the insufficient expansion effect of heating is poor, and if the amount of entry is too small, microwave resources are wasted. Therefore, it is necessary to quantitatively enter the tobacco into the microwave expansion device. The tobacco shredder 222 can be arranged to temporarily store the loose impregnated shredded tobacco in the tobacco storage bin 222 and uniformly discharge it through the outlet of the storage bin. The conveyor belt 224, which falls into the vibration groove 223, functions to further loosen the tobacco and utilize a rhythmic vibration to stabilize the amount of tobacco entering the microwave expansion device on the conveyor belt 224. The purpose of providing the heater 225 in the lower chamber 220 is to vaporize the liquid medium in the surface of the tobacco and the tobacco filler, and to vaporize the medium on the surface of the tobacco as much as possible without affecting the amount of impregnation medium inside the tobacco. After the treatment, the unvaporized medium in the tobacco surface and the tobacco filler gap enters the subsequent process, resulting in waste of medium loss.

Specifically, the upper chamber 210 and/or the lower chamber 220 are provided with an exhaust port 211, and the exhaust port 211 is connected to the exhaust pipe 4. The purpose is to recover the gaseous medium released in each of the above processing steps. This achieves a recovery of the gaseous medium within the conveying device 200. The exhaust port 211 may be provided only in the upper chamber 210 or only in the lower chamber 220, and may function to recover the gaseous medium, but at the same time, the effect of separately providing the exhaust port 211 is better. The present invention preferably provides a venting port 211 in the upper chamber 210 and the lower chamber 220, respectively.

For optimizing the tobacco expansion device 300, considering the tobacco expansion device 300 into a separate space, sealing is performed to establish an insulation system for preventing air from entering, and a specific setting is provided. The expansion chamber 310, the expansion chamber outlet 303 is sealed by the rotary valve 11, and the expansion chamber 310 is provided with an exhaust port 301, and the exhaust pipe 4 is connected to the negative pressure device to realize sealing and gaseous medium suction collection.

Specifically, as shown in FIG. 4 and FIG. 5, the tobacco expansion device 300 includes an expansion chamber 310, a conveying and feeding mechanism and a heating mechanism disposed in the expansion chamber 310, and the expansion chamber outlet 303 is provided with a rotary valve 11, An exhaust port 301 is provided on the expansion chamber 310, and the exhaust port 301 is connected to the exhaust pipe 4. The purpose is to provide an independent space for the expansion chamber 310, and to seamlessly seal the inlet and outlet of the expansion chamber 310 by using a sealing valve to realize the sealing of the tobacco expansion device 300. The conveying mechanism and the heating mechanism are transported into the expansion chamber 310. The conveying and conveying mechanism conveys the shredded tobacco through the heating mechanism, the medium vaporization is collected in the expansion chamber 310, and is recovered through the exhaust port 301 on the expansion chamber 310.

Further, as shown in FIG. 6, the upper chamber 210 inlet is seamlessly sealed with the impregnation tank 100, and the outlet of the lower chamber 220 and the inlet of the expansion chamber 310 are connected by a rotary valve 11, the lower portion The outlet of the chamber 220 is seamlessly sealed to the rotary sealing valve, the inlet of the expansion chamber 310 being seamlessly sealingly connected to the rotary valve 11, the expansion chamber outlet 303 being seamlessly sealingly connected to the rotary valve 11. According to the above arrangement, the seamless connection of the joints of the various components of the system is adopted, the sealing between the conveying device 200 and the impregnation tank 100 is realized, the sealing between the conveying device 200 and the tobacco expansion device 300 is realized, and the outlet of the tobacco expansion device 300 is realized. Sealed so that the entire system is sealed. Prevents air ingress while preventing media loss.

The heating mechanism includes a microwave heating chamber 321 disposed in the expansion chamber 310. The microwave heating chamber 321 is provided with a microwave radiation port 322, and the microwave radiation 322 is connected to the microwave source 324 through the microwave delivery tube 323. The transport feeder is a conveyor belt 330 that passes through the microwave heating chamber 321. One end of the conveyor belt 330 extends below the expansion chamber inlet 302, and the impregnated tobacco leaves fall from the conveying device through the rotary valve 11 onto the conveyor belt 330. The conveyor belt carries the impregnated tobacco through the microwave heating chamber 321, and the other end of the conveyor belt 330 extends to Above the expansion chamber outlet 303, the shredded tobacco is fed out of the expansion chamber 310.

The heating mechanism used in the embodiment is microwave heating, and the single-tube high-power microwave magnetron used in the microwave heating mechanism of the present invention is used as the microwave source 324, specifically, the single-tube power reaches 20Kw and the frequency is 915MHz. In the prior art, the low power microwave magnetron is only 0.75 Kw and the wavelength is 2450 MHz. The microwave heating chamber 321 needs to be provided with a plurality of microwave units, which brings a lot of inconvenience to the installation and maintenance, and the uniformity is not good.

Advantages of 915MHz vs. 2450MHz microwave source: stronger penetrating power, up to 3 times compared with 2450MHz; single tube high power, less tube usage, simpler maintenance; higher conversion efficiency >80%, 2450MHz only 50%~60% The conversion can be increased by 20%.

In this embodiment, a single-tube high-power microwave source 324 is used, the number of microwave sources 324 is reduced, and microwave radiation ports 322 of various angles are disposed on the microwave heating chamber 321, so that the microwaves are evenly distributed in the chamber, and the heating effect is good. The microwave source 324 is disposed outside the expansion chamber 310 for convenient maintenance.

Further, the expansion chamber 310 is provided with an observation window 311 and an illumination lamp 312, and the microwave heating chamber 321 is provided with an operation window 325. Its purpose is to facilitate observation, expansion effect, equipment operation, and timely maintenance if problems occur.

Further, the medium recovery in the impregnation tank 100 is connected to the medium storage tank 10 through the medium recovery pipe 7, but the medium of the shredded tobacco contains impurities. The medium recovery pipe 7 is further provided with a purification device, and the purification device is a medium buffer tank 71 disposed on the medium recovery pipe 7 in the medium recovery direction, a thermal condensation tank 72 and a condensation junction tank 73, and the bottom of the heat condensation tank A portion of the heat medium recovery pipe 9 and the medium recovery pipe 7 between the condensation canister and the medium storage tank 10 are connected, and a gaseous medium recovery pipe 13 is further disposed between the impregnation tank 100 and the thermal condensation tank.

In the above purification process, the medium in the impregnation tank 100 is in a gas-liquid mixed state, and the liquid medium is recovered into the medium buffer tank 71. In the medium buffer tank 71, the saturated steam is taken away, and the liquid medium is taken away from the shell, so that the liquid medium is quickly taken. The vaporization is heated, and the initially purified gaseous medium enters the thermal condensation tank 72. The hot condensation tank is filled with 70° hot water, and the gaseous medium is cooled by the thermal condensation tank 72, and then the gaseous medium enters the condensation junction tank 73, from the condensation junction tank 73. The temperature of the cold water sprayed at the top is about 12°, and the liquefied medium and part of the water flow through the heat medium recovery pipe 9 Into the medium storage tank 10. In the medium storage tank 10, the water and the medium are layered, the lower layer medium is recycled, and the upper layer of water is cooled and used for the cooling cycle.

After the liquid medium is recovered, the gaseous medium in the impregnation tank 100 is recovered to the thermal condensation tank 72 through the gaseous medium tube, and the gaseous medium is initially cooled, and is condensed by the spray water when entering the condensation junction tank 73. Finally, it enters the medium storage tank 10 through the medium recovery pipe 7.

Further, a media metering tank 12 is further included, which is connected to the medium spray pipe 8.

The purpose of the medium metering tank 12 is to extract the purified medium in the lower layer of the medium storage tank 10 for use in the metering tank, to ensure the purity of the medium, and to measure the amount of the medium.

Other embodiments:

As shown in FIGS. 7 and 8, in the other two embodiments, the vacuum device may be connected to the only conveying device 200 or only to the tobacco expansion device 300, or may be connected at the same time, as shown in FIG. Embodiments in which both are connected at the same time are preferred.

The embodiments of the present invention may be further combined or substituted, and the embodiments are merely described for the preferred embodiments of the present invention, and are not intended to limit the scope and scope of the present invention. Various changes and modifications made by those skilled in the art to the technical solutions of the present invention are within the scope of the present invention.

Claims

A tobacco expansion process for reducing dielectric loss, comprising the steps of:

(1) impregnation: impregnating the shredded tobacco in a medium to form impregnated shredded tobacco;

(2) Medium recovery: recovery of liquid and gaseous medium in the impregnation equipment;

(3) Transportation: After the impregnated tobacco is loosely processed, it is sent to the tobacco expansion device by vibration quantitatively, and the surface of the impregnated tobacco is heated to evaporate and vaporize the liquid medium on the surface of the impregnated tobacco;

(4) Expansion: heating the impregnated tobacco in the tobacco expansion device to evaporate and vaporize the liquid medium inside the impregnated tobacco to obtain expanded tobacco; the characteristic is:

(5) Secondary recovery of the medium: recovering the gaseous medium evaporated in the steps (3) and/or (4), and compressing and condensing the gaseous medium into a liquid state and storing.
A tobacco expansion process for reducing dielectric loss according to claim 1, wherein the step (3) recovers the gaseous medium in a vacuum environment having a pressure of from 20 kPa to 50 kPa.
A tobacco shuffling process for reducing dielectric loss according to claim 1, wherein the step (4) recovers the gaseous medium in a vacuum environment having a pressure of from 20 kPa to 50 kPa.
A tobacco expansion process for reducing dielectric loss according to claim 1, characterized in that the step (5) recovering the gaseous medium is recovered by a compressor under negative pressure, and the compressor pressure is from 700 kPa to 1500 kPa.
A tobacco expansion process for reducing dielectric loss according to claim 1, wherein said compressing in said step (5) comprises partially compressing the gaseous medium into a liquid medium in the compressor, and the compressor pressure is from 700 kPa to 1500 kPa.
A tobacco expansion process for reducing dielectric loss according to claim 1, wherein the condensing in the step (5) comprises cooling the compressed gaseous and liquid medium in a water-cooled condenser to condense the gaseous medium into a liquid medium. The condensate temperature is 10°-15°.
A tobacco shuffling process for reducing dielectric loss according to claim 1, characterized in that The purifying in the step (5) comprises stratifying the condensed liquid medium, extracting the liquid medium and discharging the non-condensable gas.
A tobacco expansion process for reducing dielectric loss according to claim 1, wherein the storing of the step (5) comprises feeding the purified liquid medium into a medium storage tank for storage.
A tobacco expansion process for reducing dielectric loss according to claim 3, wherein the step (4) is performed by microwave heating, and the microwave source is a microwave tube of 20 Kw and a frequency of 915 MHz.
A tobacco expansion process for reducing dielectric loss according to claim 1, characterized in that the medium recovered in the steps (2) and (5) is supplied to the step (1) impregnated tobacco.