US20130168457A1

US20130168457A1 - Method for storing tobacco

Info

Publication number: US20130168457A1
Application number: US13/716,082
Authority: US
Inventors: Yiwei Li
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-12-28
Filing date: 2012-12-14
Publication date: 2013-07-04
Also published as: CN102845823A; CN102845823B; CN102551184A

Abstract

A method for storing tobacco, including: 1) constructing a sealed plastic tent system for a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse; and 2) performing fumigation, dehumidification, and/or a combination thereof for the tobacco stack.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119 and the Paris Convention Treaty, this application claims the benefit of Chinese Patent Application No. 201110448784.0 filed Dec. 28, 2011, the contents of which, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl P.C., Attn.: Dr. Matthias Scholl Esq., 14781 Memorial Drive, Suite 1319, Houston, Tex. 77079.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a method for storing tobacco.
2. Description of the Related Art
Tobacco leaves are easy to be attacked by pests and mold during storage, moreover, problems like daily ventilization, cooling, drying, dehumidification, and normal alcoholization of the tobacco leaves under natural conditions need to be properly solved.
At present, most tobacco leaves are stored in warehouses, some warehouses feature good air-tightness and have air-conditioners or dehumidifier installed therein, and the others employ a normally natural storage method, in which two rounds of fumigated disinfestations are performed via phosphine every year, and poisonous gas generated after fumigation is discharged from the warehouses, and daily maintenance of the tobacco leaves is based on natural ventilation. However, this method has many problems with maintenance and insect prevention of the tobacco leaves:

- 1. phosphine gas is led into sealed space surrounded by a plastic sealing tent for the purpose of gas fumigated disinfestation, and a key factor determining effect of the phosphine fumigated disinfestation is dosage and sealing time of phosphine taken by pests in the tobacco leaves, but how to improve fumigation effect via high nitrogen and low oxygen environment has not been disclosed in the prior art;
- 2. if mixed gas of nitrogen and carbon dioxide is used for fumigant prevention of pests in tobacco leaves, gas cylinders of carbon dioxide are difficult to purchase and transport, and there are still several factors that cannot be facilitated in practice; and
- 3. a fumigation method using sulfuryl fluoride is currently widely used, sulfuryl fluoride does not corrode metal devices, and fumigated disinfestation features good effect, but how to carry out the fumigant prevention by mixed gas of nitrogen and low-dose sulfuryl fluoride has not been disclosed in the prior art.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems, it is one objective of the invention to provide a method for storing tobacco that features simple process, safe fumigated disinfestation, convenient humidity protection and mold prevention, and perfect energy-saving and emission-reduction.
To achieve the above objectives, in accordance with one embodiment of the invention, provided is a method for storing tobacco, comprising:
1) constructing a sealed plastic tent system for a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, comprising:

- a) disposing a main ventilating pipe in the tobacco warehouse, the main ventilating pipe comprising a group of main blower pipe and a group of main exhaust pipes, multiple branch vents being extended from the main blower pipes and the main exhaust pipes, multiple vent hoses being connected to the branch vents whereby further being connected to plastic tents that seal tobacco stack, the main ventilating pipes being connected to an exhauster, a blower, a nitrogen generator, and a dehumidifier, respectively;
- b) piling up tobacco leaves on the ground of the warehouse between the main blower pipe and the main exhaust pipe: first, making a plastic square plastic film larger than the tobacco stack via a plastic film according to size of the tobacco stack; second, pilling up tobacco leaves on the plastic film, producing a plastic sealing tent covering the sealed tobacco stack via the plastic film, covering the tobacco stack with the plastic sealing tent, sealing parts of the plastic sealing tent in the vicinity of the ground with the plastic film, piled tobacco stack sealed within a space surrounded by the plastic sealing tent and the plastic film; respectively disposing a group of inlet control joints and outlet control joints each comprising end covers on any two opposite sides of the plastic sealing tent, and end of each of the inlet control joint and the outlet control joint being disposed outside a space surrounded by the plastic sealing tent and the plastic film, and the other end of each of the inlet control joint and the outlet control joint being disposed in the space surrounded by the plastic sealing tent and the plastic film;
- c) connecting the inlet control joint and the outlet control joint on the plastic tent with the branch vent on the main ventilating pipe in the tobacco warehouse via a soft pipe; the ventilating pipe, the plastic sealing tent and the plastic film, and the inlet control joint, the outlet control joint, the connection pipe, and the pipe control valve disposed on the plastic sealing tent forming the sealed plastic tent system capable of mechanically controlling internal storage conditions;

2) performing any one of following steps (1) and (2), step (1) first and then step (2), or step (2) first and then step (1):

- (1) mechanically introducing mixed gas of nitrogen and phosphine or sulfuryl fluoride for the purpose of fumigant prevention whereby preventing pests in the tobacco stack, according to following step d) or e):
  - d) fumigation combining high-concentration nitrogen with low-dose phosphine: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with the nitrogen generator via the ventilating pipe, keeping the inlet control joint and the outlet control joint on the sealing tent, and a valve on the connection pipe at an “on” state, slowly introducing nitrogen into the tobacco stack via positive pressure of the nitrogen generator, and forcing old air in the tobacco stack out of the plastic sealing tent via the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, until column concentration of nitrogen in the plastic sealing tent is above 85%, at this time switching off the nitrogen generator, the inlet control joint and the outlet control joint on the sealing tent of the tobacco stack, manually introducing phosphine into the sealed tobacco stack, until volume concentration thereof is 30-700 ppm, so that finally in the sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of phosphine is 30-700 ppm;
  - e) fumigation combining high-concentration nitrogen with low-dose sulfuryl fluoride: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with the nitrogen generator via the ventilating pipe, keeping the inlet control joint and the outlet control joint on the sealing tent, and a valve on the connection pipe at an “on” state, slowly introducing nitrogen into the tobacco stack via positive pressure of the nitrogen generator, and forcing old air in the tobacco stack out of the plastic sealing tent via the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, until column concentration of nitrogen in the plastic sealing tent is above 85%, at this time switching off the nitrogen generator, the inlet control joint and the outlet control joint on the sealing tent of the tobacco stack, manually introducing phosphine into the sealed tobacco stack, until volume concentration thereof is 50-700 ppm, so that finally in the sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of sulfuryl fluoride is 50-700 ppm;
- (2) switching on a dehumidifier, mechanically and directionally introducing air into the sealed tobacco stack, and performing dehumidification whereby removing accumulated heat and humidity in the tobacco stack;
  - after step 1), as heat and humidity are accumulated in the tobacco stack within sealed space formed by the plastic sealing tent and the plastic film, following step f), g), h), or a combination thereof is used to remove the heat and humidity:
  - f) single-direction blowing and dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic tent of the tobacco stack with an air outlet of the dehumidifier via a ventilating pipe, switching on the inlet control joint, the outlet control joint, the valve on the connection pipe, and the dehumidifier, and simultaneously switching on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent of the tobacco stack, whereby blowing and dehumidifying the sealed space of the tobacco stack in a single direction, fresh air is gradually introduced and used to replace old and humid air in the tobacco stack, until relative air humidity in sealed space formed by the plastic sealing tent and the plastic film is less than 65%;
  - the single-direction blowing and dehumidification system of the dehumidifier connects the inlet control joint and the outlet control joint on the other side of the plastic sealing tent with a centrifugal exhauster via the ventilating pipe, the centrifugal exhauster improves circulating dehumidification efficiency within the sealing tent of the tobacco stack by exhausting and driving of the centrifugal exhauster;
  - g) circulating dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with an outlet pipe of the dehumidifier, connecting the inlet control joint and the outlet control joint on the other side of the plastic sealing tent with a return-air pipe of the dehumidifier, switching on the inlet control joint, the outlet control joint, and the valve on the connection pipe, and thus a power-saving circulating dehumidification system combining blowing with air returning is formed, until air humidity in the sealed space formed by the plastic sealing tent and the plastic film is less than 65%;
  - h) mechanical ventilation, dehumidification, and removal of accumulated heat of a centrifugal fan in a single direction: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent to the blower or the centrifugal exhauster via the main ventilating pipe, switching on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, and the blower or the centrifugal exhauster, and performing single-direction blowing or exhausting whereby removing accumulated heat and humidity in the sealed space formed by the plastic sealing tent and the plastic film as air temperature in the plastic sealing tent is greater than that outside the plastic sealing tent, or if temperature of the tobacco stack abnormally rises.

In a class of this embodiment, after forming the sealed plastic tent system capable of mechanically controlling internal storage conditions, phosphine fumigant is used to prevent pests in tobacco leaves according to the following steps:

- 1) using aluminum phosphide or magnesium phosphide for fumigation, switching off the inlet control joint and the outlet control joint on the plastic sealing tent, calculating dosage of aluminum phosphide or magnesium phosphide required by the plastic sealing tent according to dosage of 1-8 g/m³, and finally putting reagent into sealed space surrounded by the plastic sealing tent and keeping it at a sealed state;
- 2) combining phosphine with carbon dioxide for fumigation, switching off the inlet control joint and the outlet control joint on the plastic sealing tent, calculating dosage of aluminum phosphide required by the plastic sealing tent according to dosage of 0.5-3 g/m³, and amount of carbon dioxide required by the plastic sealing tent according to dosage of 10-50 g/m³, intensively mixing phosphine generated by carbon dioxide and aluminum phosphide in a steel cylinder, and injecting phosphine into the sealed space surrounded by the plastic sealing tent via an applicator, volume concentration of phosphine being 30-700 ppm, and sealed state of the plastic tent kept for more than three days.

In a class of this embodiment, after fumigation combining high-concentration nitrogen with low-dose phosphine or fumigation combining high-concentration nitrogen with low-dose sulfuryl fluoride in step 2), the inlet control joint and the outlet control joint on one side of the plastic sealing tent are connected to an exhaust gas filtering and purifying device for fumigation via a main ventilating pipe, the centrifugal exhauster, and the inlet control joint and the outlet control joint on the other side of the plastic sealing tent are switched on whereby pumping out poisonous exhaust gas in the sealed space formed by the plastic sealing tent and the plastic film during fumigation, and blowing the gas into the exhaust gas filtering and purifying device for fumigation for further filtering and purification.
In a class of this embodiment, the number of the inlet control joints and the out control joints comprising the end covers is 1 to 30.
In a class of this embodiment, the plastic sealing tent is made from plastic film or Nylon composite film.
In a class of this embodiment, a volume concentration of the high-concentration nitrogen is greater than or equal to 85%.
In a class of this embodiment, the exhaust gas filtering and purifying device employs a poisonous gas filtering and purifying device in the prior art, or an absorption tower, an exhaust gas purification tower, a filtering device, a phosphine filtering and absorption device, a phosphine gas filtering device, a phosphine gas collector, a phosphine gas processing device, a phosphine gas purifying device, a sulfuryl fluoride filtering and absorption device in the prior art.
Advantages of the method for storing tobacco of the invention are summarized below:

- 1. by using a method of mixing high-dose nitrogen with low-dose phosphine for fumigation, effect of preventing pests by nitrogen regulation and phosphine fumigation is greatly improved;
- 2. by using high-concentration nitrogen and fumigation using low-dose sulfuryl fluoride, in the sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of sulfuryl fluoride is 50-700 ppm, which provides a new, safe and environment-friendly fumigation mode for fumigant prevention of pests in the tobacco leaves.
- 3. the method is simple, fumigated disinfestation is safe, which make the invention convenient for drying and mold-prevention, and the method features perfect energy-saving and emission-reduction.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

FIG. 1-1 is illustrates constructing a sealed plastic tent system capable of mechanically controlling internal storage conditions in a tobacco warehouse;

FIG. 1-2 is a top view of FIG. 1-1;

FIG. 2 is an enlarged view of a portion A in FIG. 1-2;

FIG. 3 illustrates a ventilation circuit formed by multiple plastic sealing tents connected in series;

FIG. 4 illustrates a single-direction-exhaust ventilation circuit formed by multiple plastic sealing tents;

FIG. 5 illustrates a single-direction-blowing ventilation circuit formed by multiple plastic sealing tents;

FIG. 6 illustrates a ventilation circuit formed by multiple plastic sealing tents connected in parallel; and

FIG. 7 illustrates variation of concentration of phosphine at different stack positions.

In the drawings, the following reference numbers are used: 1-plastic sealing tent, 2-tobacco stack, 3-a group of inlet control joints and outlet control joints, 4-the other group of inlet control joints and outlet control joints, 5-pest trap, 6-plastic film, 7-plastic groove tube, 8-rubber tube, 9-main blower pipe, 10-exhaust vent, 11-main exhaust pipe, 12-blowing vent.

DETAILED DESCRIPTION OF THE EMBODIMENTS

For further illustrating the invention, experiments detailing a method for storing tobacco are described below. It should be noted that the following examples are intended to describe and not to limit the invention.

Example 1

A method for storing tobacco is described as follows.
1) Constructing a sealed plastic tent system for a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, namely, constructing six-side-sealed space for a tobacco stack capable of mechanically controlling storage conditions (as shown in FIGS. 1-1, 1-2, and 2), comprises steps of:

- a) disposing a main ventilating pipe in the tobacco warehouse, the main ventilating pipe comprising a group of main blower pipes and a group of main exhaust pipes, multiple branch vents being extended from the main blower pipes and the main exhaust pipes, multiple vent hoses being connected to the branch vents whereby further being connected to plastic tents that seal tobacco stack, the main ventilating pipes being respectively connected to a centrifugal exhauster, a blower, a nitrogen generator, and a dehumidifier; in this example, the number of the branch vents is 2 to 50, and is determined by size and the number of the tobacco warehouses;
- b) piling up tobacco leaves on the ground of the warehouse between the main blower pipe 9 and the main exhaust pipe 11: first, making a plastic square plastic film 6 larger than the tobacco stack via a plastic film according to size of the tobacco stack, then pilling up tobacco leaves on the plastic film, producing a plastic sealing tent 1 covering the sealed tobacco stack via the plastic film, covering the tobacco stack 2 with the plastic sealing tent 1, sealing parts of the plastic sealing tent 1 in the vicinity of the ground with the plastic film 6, piled tobacco stack 2 sealed within a space surrounded by the plastic sealing tent and the plastic film; respectively disposing a group of inlet control joints and outlet control joints each comprising end covers (a group of inlet control joints and outlet control joints 3 on one side, and a group of inlet control joints and outlet control joints 4 on the other side) on any two opposite sides of the plastic sealing tent 1, and end of each of the inlet control joint and the outlet control joint disposed outside a space surrounded by the plastic sealing tent and the plastic film, the other end of each of the inlet control joint and the outlet control joint disposed in the space surrounded by the plastic sealing tent and the plastic film;
- c) connecting the inlet control joint and the outlet control joint on the plastic tent with the branch vent on the main ventilating pipe in the tobacco warehouse via a soft pipe as far as sealing stack to be mechanically controlled is concerned (the main ventilating pipe comprises a group of main blower pipes, the branch vent is the blowing vent 12, the main ventilating pipe comprises a group of main exhaust pipes, the branch vent is the exhaust vent 10).

The ventilating pipe, the plastic sealing tent and the plastic film, and the inlet control joint, the outlet control joint, the connection pipe, and the pipe control valve are disposed on the plastic sealing tent to form a sealed plastic tent system for a tobacco stack capable of mechanically controlling internal storage conditions.
A group of inlet control joints and outlet control joints 3 (the number thereof is 1-30), and another group of inlet control joints and outlet control joints 4 (the number thereof is 1-30) are respectively disposed on any opposite sides of the plastic sealing tent 1, or on positions at the top of the plastic sealing tent and on the plastic film 6 (or referred to as plastic base interlining) corresponding to each other, or a group of inlet control joints and outlet control joints are disposed on the plastic film 6, and the other group of inlet control joints and outlet control joints are disposed at the top of and on four sides of the plastic sealing tent.
For example, a group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) are disposed on the left side of the plastic sealing tent 1, and the other group of inlet control joints and outlet control joints 4 (or a group of inlet control joints and outlet control joints 3) are disposed on the right side of the plastic sealing tent 1.
A skirt of the plastic sealing tent in the vicinity of the ground and the plastic film 6 are double laminated or folding sealed using the following method: double laminating the skirt of the plastic sealing tent 1 in the vicinity of the ground and unnecessary parts in around the plastic film 6, and then putting it into a plastic groove tube 7 with a groove, and pressing an elastic rubber tube 8 on the plastic groove tube for fixing whereby forming tightly sealed storage space.
The group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) operate as air exchange channels between the sealed space surrounded by the plastic sealing tent and the outside as being switched on, and keep the sealed space surround by the plastic sealing tent at a completely sealed state as being switched off. The group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) can be control joints capable of controlling air exchange, and can employ various structure and materials (such as metal or plastics), a commonly-used structure is that a control valve is disposed on the pipe, or a screw-connected and closed end cover is disposed on an end of the pipe, or a lid is pressed into an internal hole on an end of the pipe, and so on.
The group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) operate as exchange channels of gas and medium between the sealed space surrounded by the plastic sealing tent 1 and the tobacco stack 2 and the outside, and of air in the tobacco stack, and can be freely switched on or off; the plastic sealing tent 1 can facilitate separated pest control and gas fumigated disinfestation at any time, and maintain tight sealing of the tent for the tobacco stack after fumigation until a storage cycle for the tobacco leaves is finished; after switching on a group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) and connecting them to corresponding devices, functions such as fumigated disinfestation, toxicant elimination and dehumidification can be facilitated; after switching off a group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4), a storage and maintenance environment with stable sealing performance can be kept in the sealed tobacco stack.
In this example, the plastic sealing tent 1 and the plastic film 6 form a plastic sealing tent for a tobacco stack capable of mechanically controlling a storage environment of the tobacco leaves.
In this example, a pipe valve is connected on a pipe connecting the group of inlet control joints and outlet control joints 3 and the other group of inlet control joints and outlet control joints 4 on the plastic sealing tent with the branch vent.
A pest trap 5 is disposed in the sealed space surrounded by the plastic sealing tent and the plastic film.
In this example, the plastic sealing tent for a tobacco stack in step 1) can be made into a group of ventilating systems for plastic sealing tent for tobacco stacks according to one of the following methods:

- A) Multiple (2-30) plastic sealing tents for a tobacco stack form a group of plastic sealing tents for a tobacco stack, a group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) on a sealing tent for the first tobacco stack are connected to a blowing vent 12 on the main blower pipe 9 in the warehouse, and the other group of inlet control joints and outlet control joints 4 (or a group of inlet control joints and outlet control joints 3) are connected to a group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) on a plastic sealing tent for the next tobacco stack via a hose, and so on, and finally, the other group of inlet control joints and outlet control joints 4 (or a group of inlet control joints and outlet control joints 3) on a plastic sealing tent for the last tobacco stack are connected to the exhaust vent 10 on the main exhaust pipe 11 in the warehouse, whereby constructing a power-saving ventilation circuit formed by multiple plastic sealing tents for a tobacco stack connected in series (as shown in FIG. 3).
- B) Multiple (2-30) plastic sealing tents for a tobacco stack form a group of plastic sealing tents for a tobacco stack, the other group of inlet control joints and outlet control joints 4 on the sealing tent for each tobacco stack are connected to the exhaust vent 10 on the main exhaust pipe 11 in the tobacco warehouse via a hose, and so on, and finally a power-saving single-direction-exhaust ventilation circuit formed by multiple plastic sealing tents connected in parallel is constructed (as shown in FIG. 4).
- For one group of plastic sealing tents for a tobacco stack, an uppermost group of inlet control joints and outlet control joints thereof are connected to the blowing vent 12 on the main blower pipe 9 in the tobacco warehouse via a hose, and so on, finally a power-saving single-direction-blowing ventilation circuit formed by multiple plastic sealing tents connected in parallel is constructed (as shown in FIG. 5);
- C) Multiple (2-30) plastic sealing tents for a tobacco stack form a group of plastic sealing tents for a tobacco stack, for a plastic sealing tent in the group of plastic sealing tents for a tobacco stack, a group of inlet control joints and outlet control joints 3 (or the other group of inlet control joints and outlet control joints 4) on a sealing tent for each first tobacco stack are connected to a blowing vent 12 on the main blower pipe 9 in the warehouse, and the other group of inlet control joints and outlet control joints 4 (or a group of inlet control joints and outlet control joints 3) on a plastic sealing tent for each tobacco stack are connected to the exhaust vent 10 on the main exhaust pipe 11 in the tobacco warehouse, and so on, and finally, a power-saving ventilation circuit combining blowing and exhausting and formed by multiple plastic sealing tents connected in parallel is constructed (as shown in FIG. 6).

2) Mechanically introducing mixed gas comprising nitrogen for the purpose of fumigant prevention whereby preventing pests in the tobacco stack, and performing manual mechanical removal in case that humidity or heat occur in the tobacco stack, comprises:
(1) mechanically introducing mixed gas of nitrogen and phosphine or sulfuryl fluoride for the purpose of fumigant prevention whereby preventing pests in the tobacco stack, comprising the following method:

- fumigation combining high-concentration nitrogen with low-dose phosphine: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with the nitrogen generator via the ventilating pipe, keeping the inlet control joint and the outlet control joint on the sealing tent, and a valve on the connection pipe at an “on” state, slowly introducing nitrogen into the tobacco stack via positive pressure of the nitrogen generator, and forcing old air in the tobacco stack out of the plastic sealing tent via the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, until column concentration of nitrogen in the plastic sealing tent is above 85%, at this time switching off the nitrogen generator, the inlet control joint and the outlet control joint on the sealing tent of the tobacco stack, manually introducing phosphine into the sealed tobacco stack, until volume concentration thereof is 30-700 ppm, so that finally in the sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of phosphine is 30-700 ppm.

The phosphine gas can be generated by putting aluminum phosphide or magnesium phosphide tablets into the tobacco stack, and then the aluminum phosphide tablets naturally absorb water in the air, deliquesce and finally generate phosphine, or by putting the aluminum phosphide into a phosphine generator, which reacts with water and generates phosphine gas, and finally the gas is mixed with carbon dioxide and then injected into the sealing stack.
After fumigation is completed, to facilitate a safe and environment-friendly fumigation environment, the inlet control joint and the outlet control joint on one side of the plastic sealing tent are connected to the exhaust gas filtering and purifying device for fumigation via the main ventilating pipe, the centrifugal exhauster, and the inlet control joint and the outlet control join on the other side of the plastic sealing tent are switched on, whereby pumping out poisonous exhaust gas in the sealed space formed by the plastic sealing tent and the plastic film during fumigation, and blowing the gas into the exhaust gas filtering and purifying device for fumigation for further filtering and purification.
The Moshan warehouse of Wuhan Tobacco Co., Ltd used the above-mentioned fumigation method combining high-concentration nitrogen with low-dose phosphine to perform fumigated disinfestation in a plastic sealing tent for a tobacco stack in the 19^thwarehouse from October to November in 2011, and comparatively satisfactory pest killing effect was obtained.
The test comprises tightness detection of the tobacco stack, manual repairing of film of a tent, and rearrangement of plastic grooves and pipes, whereby ensuring tightness at different stack positions meet inflating requirements. Firstly, beetles are put in stacks, and then inflation, exhaust and detection start, after several times of repeation, as nitrogen concentration in the stacks reaches a certain value, aluminum phosphide is put in, sealing time is set, and finally the pests are determined whether die or not.
During inflation, firstly a sealing mouth is opened, and the exhauster is used for exhausting until the film is tightly attached to a smoke box, at the time inflation is stopped, a nitrogen transmission pipe is connected to a gas supply opening of the stack, and nitrogen filling starts, as the film is expanded, inflation is stopped, after half an hour, nitrogen concentration is tested, if it does not reach a standard, the above process (exhaust, inflation and test) is repeated until a predetermined concentration is reached.
Nitrogen concentration is tested once every day, and stacks leaking gas are supplied with gas, until the standard is reached.
After the predetermined concentration is reached, aluminum phosphide tablets are put into the stack according to size of the stack positions and a dosage of 1 g/m³, and living states of the beetles in the stacks are checked in the 3^rd, 7^th, 10^th, 13^th, and 16^thdays, and the number and growth status thereof are recorded.
Assuming there are four sealing stack positions having nitrogen concentration of 99%: A4, A5, B4, and B5, and two blanks for reference CK1 and CK2, as shown in the following Table 1:

TABLE 1

	Volume concentration	Sealing and checking
No. of stack position	of nitrogen	time (day)

A4	99%	7, 10, 13, 16
A5	99%	7, 10, 13, 16
B4	95%	7, 10, 13, 16
B5	95%	7, 10, 13, 16

By using nitrogen generators to continuously inflate and supply gas, each stack position reaches the predetermined concentration on October 26, drugs are put in the position (dosage of the aluminum phosphide tablet is 1 g/m³), phosphine concentration in the plastic sealing tent is illustrated in FIG. 7. For pests respectively taken from the smoke box 7 days (November 2), 10 days (November 5), 13 days (November 8), and 16 days (November 11) from the day on which nitrogen concentration reaches a predetermined value, brushes are used to slightly contact therewith, and results are recorded as shown in the following Table 2:

	TABLE 2

	Whether a living pest exists?

Duration of inflation (day)	A4	A5	B4	B5	CK1	CK2

7	No	No	Yes	No	Yes	Yes
10	No	No	No	No	Yes	Yes
13	No	No	No	No	Yes	Yes
16	No	No	No	no	Yes	Yes

The nitrogen generator can employ a pressure swing adsorption nitrogen generator, or a membrane nitrogen generator.
Operation performance of the nitrogen generator can be determined by testing oxygen concentration in the sealing stack via an oxygen concentration detector or an automatic oxygen detector.
(2) Manual or mechanical dehumidification and heat elimination
after step 1), as heat and humidity are accumulated in the tobacco stack within sealed space formed by the plastic sealing tent and the plastic film, any one or more of the following methods is used to remove them: single-direction blowing and dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic tent of the tobacco stack with an air outlet of the dehumidifier via a ventilating pipe, switching on the inlet control joint, the outlet control joint, the valve on the connection pipe, and the dehumidifier, and simultaneously switching on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent of the tobacco stack, whereby blowing and dehumidifying the sealed space of the tobacco stack in a single direction, fresh air is gradually introduced and used to replace old and humid air in the tobacco stack, until relative air humidity in sealed space formed by the plastic sealing tent and the plastic film is less than 65%.

Example 2

This example is almost the same as example 1, except that: 2) after step 1), mixed gas of nitrogen and sulfuryl fluoride is mechanically introduced for fumigant prevention whereby preventing pests in the tobacco stack.
Mixed gas of nitrogen and sulfuryl fluoride is introduced for fumigant prevention, and the following steps are taken for fumigant prevention of pests in the tobacco stack:

- connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with the nitrogen generator via the ventilating pipe, keeping the inlet control joint and the outlet control joint on the sealing tent, and a valve on the connection pipe at an “on” state, slowly introducing nitrogen into the tobacco stack via positive pressure of the nitrogen generator, and forcing old air in the tobacco stack out of the plastic sealing tent via the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, until column concentration of nitrogen in the plastic sealing tent is above 85%, at this time switching off the nitrogen generator, the inlet control joint and the outlet control joint on the sealing tent of the tobacco stack, manually introducing phosphine into the sealed tobacco stack, until volume concentration thereof is 50-700 ppm, so that finally in the sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of sulfuryl fluoride is 50-700 ppm.

In this example, sulfuryl fluoride can be contained in a steel cylinder purchased from a relevant manufacturer.
Test and results of this example are the same as those in example 1.

Example 3

This example is almost the same as example 1, except for a working mode of manually or mechanically removing heat and humidity in the tobacco stack.
After step 1), the following steps are taken to remove heat and humidity in the tobacco stack in the sealed space formed by the plastic sealing tent and the plastic film:

- circulating dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with an outlet pipe of the dehumidifier, connecting the inlet control joint and the outlet control joint on the other side of the plastic sealing tent with a return-air pipe of the dehumidifier (a centrifugal exhauster can be serially connected to the middle of the return-air pipe), switching on the inlet control joint, the outlet control joint, and the valve on the connection pipe, and thus a power-saving circulating dehumidification system combining blowing with air returning is formed, until air humidity in the sealed space formed by the plastic sealing tent and the plastic film is less than 65%.

Test and results of this example are the same as those in example 1.

Example 4

- mechanical ventilation, dehumidification, and removal of accumulated heat of a centrifugal fan in a single direction: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent to the blower or the centrifugal exhauster via the main ventilating pipe, switching on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, and the blower or the centrifugal exhauster, and performing single-direction blowing or exhausting whereby removing accumulated heat and humidity in the sealed space formed by the plastic sealing tent and the plastic film as air temperature in the plastic sealing tent is greater than that outside the plastic sealing tent, or if temperature of the tobacco stack abnormally rises (≧30° C.).

Test and results of this example are the same as those in example 1.

Example 5

This example is almost the same as example 1, except that: 2) after step 1), mixed gas of nitrogen and sulfuryl fluoride is mechanically introduced for fumigant prevention whereby preventing pests in the tobacco stack, and heat and humidity in the tobacco stack are manually or mechanically removed:
(1) mixed gas of nitrogen and sulfuryl fluoride is introduced for fumigant prevention, and the following steps are taken for fumigant prevention of pests in the tobacco stack:

(2) circulating dehumidification of the dehumidifier:
After step 1), the following steps are taken to remove heat and humidity in the tobacco stack in the sealed space formed by the plastic sealing tent and the plastic film:

Test and results of this example are the same as those in example 1.

Example 6

This example is almost the same as example 5, except for a working mode of manually or mechanically removing heat and humidity in the tobacco stack.
After step 1), the following step is taken to remove heat and humidity in the tobacco stack in the sealed space formed by the plastic sealing tent and the plastic film:

- single-direction blowing and dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic tent of the tobacco stack with an air outlet of the dehumidifier via a ventilating pipe, switching on the inlet control joint, the outlet control joint, the valve on the connection pipe, and the dehumidifier, and simultaneously on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent of the tobacco stack, whereby blowing and dehumidifying the sealed space of the tobacco stack in a single direction, fresh air is gradually introduced and used to replace old and humid air in the tobacco stack, until relative air humidity in sealed space formed by the plastic sealing tent and the plastic film is less than 65%.

The single-direction blowing and dehumidification system of the dehumidifier connects the inlet control joint and the outlet control joint on the other side of the plastic sealing tent with a centrifugal exhauster via the ventilating pipe, the centrifugal exhauster improves circulating dehumidification efficiency within the sealing tent of the tobacco stack by exhausting and driving of the centrifugal exhauster.
Test and results of this example are the same as those in example 1.

Example 7

This example is almost the same as example 5, except for a working mode of manually or mechanically removing heat and humidity in the tobacco stack.
After step 1), the following steps are taken to remove heat and humidity in the tobacco stack in the sealed space formed by the plastic sealing tent and the plastic film:

Test and results of this example are the same as those in example 1.

Example 8

This example is almost the same as example 1, except that after constructing the sealed plastic tent system in the tobacco stack capable of mechanically controlling internal storage conditions, phosphine fumigant is used to prevent pests in tobacco leaves according to the following steps:

- using aluminum phosphide for fumigation, switching off the inlet control joint and the outlet control joint on the plastic sealing tent, calculating dosage of aluminum phosphide required by the plastic sealing tent according to dosage of 1-8 g/m³, and finally putting reagent into sealed space surrounded by the plastic sealing tent and keeping it at a sealed state.

Test and results of this example are the same as those in example 1.

Example 9

This example is almost the same as example 1, except that after constructing the sealed plastic tent system in the tobacco stack capable of mechanically controlling internal storage conditions, phosphine fumigant is used to prevent pests in tobacco leaves according to the following steps: combining phosphine with carbon dioxide for fumigation, switching off the inlet control joint and the outlet control joint on the plastic sealing tent, calculating dosage of aluminum phosphide required by the plastic sealing tent according to dosage of 0.5-3 g/m³, and amount of carbon dioxide required by the plastic sealing tent according to dosage of 10-30 g/m³, intensively mixing phosphine generated by carbon dioxide and aluminum phosphide in a steel cylinder, and injecting phosphine into the sealed space surrounded by the plastic sealing tent via an applicator, volume concentration of phosphine being 30-700 ppm, and sealed state of the plastic tent kept for more than three days.
Test and results of this example are the same as those in example 1.

Example 10

A method for storing tobacco comprises steps of:
1) constructing a sealed plastic tent system in a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, as described in example 1.
2) after step 1), the following steps are taken:
mechanically introducing mixed gas of nitrogen and phosphine for the purpose of fumigant prevention whereby preventing pests in the tobacco stack, comprising the following method:

Test and results of this example are the same as those in example 1.

Example 11

A method for storing tobacco comprises steps of:
1) constructing a sealed plastic tent system in a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, as described in example 1.
2) after step 1), the following steps are taken:
mixed gas of nitrogen and sulfuryl fluoride is introduced for fumigant prevention, and the following steps are taken for fumigant prevention of pests in the tobacco stack:

Test and results of this example are the same as those in example 1.

Example 12

A method for storing tobacco comprises steps of:
1) constructing a sealed plastic tent system in a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, as described in example 1.
2) switching on the dehumidifier and facilitating mechanical ventilation, dehumidification, and removing accumulated heat in the sealed tobacco stack in a single direction:
After step 1), the following steps are taken to remove heat and humidity in the tobacco stack in the sealed space formed by the plastic sealing tent and the plastic film:

- single-direction blowing and dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic tent of the tobacco stack with an air outlet of the dehumidifier via a ventilating pipe, switching on the inlet control joint, the outlet control joint, the valve on the connection pipe, and the dehumidifier, and simultaneously switching on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent of the tobacco stack, whereby blowing and dehumidifying the sealed space of the tobacco stack in a single direction, fresh air is gradually introduced and used to replace old and humid air in the tobacco stack, until relative air humidity in sealed space formed by the plastic sealing tent and the plastic film is less than 65%.

Example 13

A method for storing tobacco comprises steps of:
1) constructing a sealed plastic tent system in a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, as described in example 1.
2) switching on the dehumidifier and facilitating mechanical ventilation, dehumidification, and removal of accumulated heat in the sealed tobacco stack in a single direction:
After step 1), the following steps are taken to remove heat and humidity in the tobacco stack in the sealed space formed by the plastic sealing tent and the plastic film:

- circulating dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with an outlet pipe of the dehumidifier, connecting the inlet control joint and the outlet control joint on the other side of the plastic sealing tent with a return-air pipe of the dehumidifier, switching on the inlet control joint, the outlet control joint, and the valve on the connection pipe, and thus a power-saving circulating dehumidification system combining blowing with air returning is formed, until air humidity in the sealed space formed by the plastic sealing tent and the plastic film is less than 65%;

Test and results of this example are the same as those in example 1.

Example 14

- mechanical ventilation, dehumidification, and removal of accumulated heat of a centrifugal fan in a single direction: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent to the blower or the centrifugal exhauster via the main ventilating pipe, switching on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, and the blower or the centrifugal exhauster, and performing single-direction blowing or exhausting whereby removing accumulated heat and humidity in the sealed space formed by the plastic sealing tent and the plastic film as air temperature in the plastic sealing tent is greater than that outside the plastic sealing tent, or if temperature of the tobacco stack abnormally rises.

Test and results of this example are the same as those in example 1.

Example 15

A method for storing tobacco comprises steps of:
1) constructing a sealed plastic tent system in a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, as described in example 1.
2) switching on a dehumidifier, mechanically and directionally introducing air into the sealed tobacco stack, and performing dehumidification whereby removing accumulated heat and humidity in the tobacco stack;
after step 1), as heat and humidity are accumulated in the tobacco stack within sealed space formed by the plastic sealing tent and the plastic film, any one or more of the following methods are used to remove them:

- a) single-direction blowing and dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic tent of the tobacco stack with an air outlet of the dehumidifier via a ventilating pipe, switching on the inlet control joint, the outlet control joint, the valve on the connection pipe, and the dehumidifier, and simultaneously on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent of the tobacco stack, whereby blowing and dehumidifying the sealed space of the tobacco stack in a single direction, fresh air is gradually introduced and used to replace old and humid air in the tobacco stack, until relative air humidity in sealed space formed by the plastic sealing tent and the plastic film is less than 65%;
- the single-direction blowing and dehumidification system of the dehumidifier connects the inlet control joint and the outlet control joint on the other side of the plastic sealing tent with a centrifugal exhauster via the ventilating pipe, the centrifugal exhauster improves circulating dehumidification efficiency within the sealing tent of the tobacco stack by exhausting and driving of the centrifugal exhauster;
- b) circulating dehumidification of the dehumidifier: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with an outlet pipe of the dehumidifier, connecting the inlet control joint and the outlet control joint on the other side of the plastic sealing tent with a return-air pipe of the dehumidifier, switching on the inlet control joint, the outlet control joint, and the valve on the connection pipe, and thus a power-saving circulating dehumidification system combining blowing with air returning is formed, until air humidity in the sealed space formed by the plastic sealing tent and the plastic film is less than 65%;
- c) mechanical ventilation, dehumidification, and removal of accumulated heat of a centrifugal fan in a single direction: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent to the blower or the centrifugal exhauster via the main ventilating pipe, switching on the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, and the blower or the centrifugal exhauster, and performing single-direction blowing or exhausting whereby removing accumulated heat and humidity in the sealed space formed by the plastic sealing tent and the plastic film as air temperature in the plastic sealing tent is greater than that outside the plastic sealing tent, or if temperature of the tobacco stack abnormally rises;

3) mechanically introducing mixed gas of nitrogen and phosphine or sulfuryl fluoride for the purpose of fumigant prevention whereby preventing pests in the tobacco stack, comprising any one of the following methods:

- a) fumigation combining high-concentration nitrogen with low-dose phosphine: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with the nitrogen generator via the ventilating pipe, keeping the inlet control joint and the outlet control joint on the sealing tent, and a valve on the connection pipe at an “on” state, slowly introducing nitrogen into the tobacco stack via positive pressure of the nitrogen generator, and forcing old air in the tobacco stack out of the plastic sealing tent via the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, until column concentration of nitrogen in the plastic sealing tent is above 85%, at this time switching off the nitrogen generator, the inlet control joint and the outlet control joint on the sealing tent of the tobacco stack, manually introducing phosphine into the sealed tobacco stack, until volume concentration thereof is 30-700 ppm, so that finally in the sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of phosphine is 30-700 ppm;
- b) fumigation combining high-concentration nitrogen with low-dose sulfuryl fluoride: connecting the inlet control joint and the outlet control joint on one side of the plastic sealing tent with the nitrogen generator via the ventilating pipe, keeping the inlet control joint and the outlet control joint on the sealing tent, and a valve on the connection pipe at an “on” state, slowly introducing nitrogen into the tobacco stack via positive pressure of the nitrogen generator, and forcing old air in the tobacco stack out of the plastic sealing tent via the inlet control joint and the outlet control joint on the other side of the plastic sealing tent, until column concentration of nitrogen in the plastic sealing tent is above 85%, at this time switching off the nitrogen generator, the inlet control joint and the outlet control joint on the sealing tent of the tobacco stack, manually introducing phosphine into the sealed tobacco stack, until volume concentration thereof is 50-700 ppm, so that finally in the sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of sulfuryl fluoride is 50-700 ppm.

Test and results of this example are the same as those in example 1.
While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Claims

The invention claimed is:

1. A method for storing tobacco, the method comprising:

1) constructing a sealed plastic tent system for a tobacco stack capable of mechanically controlling internal storage conditions in a tobacco warehouse, said constructing comprising the steps of:

a) disposing a main ventilating pipe in said tobacco warehouse, said main ventilating pipe comprising a group of main blower pipes and a group of main exhaust pipes, multiple branch vents being extended from said main blower pipes and said main exhaust pipes, multiple vent hoses being connected to said branch vents whereby further being connected to plastic tents that seal tobacco stack, and said main ventilating pipes being connected to an exhauster, a blower, a nitrogen generator, and a dehumidifier, respectively;

b) piling up tobacco leaves on the ground of said warehouse between said main blower pipe and said main exhaust pipe: first, making a plastic square plastic film larger than said tobacco stack via a plastic film according to size of said tobacco stack, then, pilling up tobacco leaves on said plastic film, producing a plastic sealing tent covering said sealed tobacco stack via said plastic film, covering said tobacco stack with said plastic sealing tent, sealing parts of said plastic sealing tent in the vicinity of the ground with said plastic film, piled tobacco stack sealed within a space surrounded by said plastic sealing tent and said plastic film; disposing a group of inlet control joints and outlet control joints each comprising end covers on any two opposite sides of said plastic sealing tent, and end of each of said inlet control joint and said outlet control joint disposed outside a space surrounded by said plastic sealing tent and said plastic film, the other end of each of said inlet control joint and said outlet control joint disposed in the space surrounded by said plastic sealing tent and said plastic film; and

c) connecting said inlet control joint and said outlet control joint on said plastic tent with said branch vent on said main ventilating pipe in said tobacco warehouse via a soft pipe as far as sealing stack to be mechanically controlled is concerned; said ventilating pipe, said plastic sealing tent and said plastic film, and said inlet control joint, said outlet control joint, said connection pipe, and said pipe control valve disposed on said plastic sealing tent forming a sealed plastic tent system capable of mechanically controlling internal storage conditions;

2) performing fumigant prevention, dehumidification, or a combination thereof for said tobacco stack, wherein the fumigant prevention is carried out according to step d) or step e):

d) fumigation combining nitrogen with phosphine: connecting said inlet control joint and said outlet control joint on one side of said plastic sealing tent with said nitrogen generator via said ventilating pipe, keeping said inlet control joint and said outlet control joint on said sealing tent, and a valve on said connection pipe at an “on” state, introducing nitrogen into said tobacco stack via positive pressure of said nitrogen generator, and forcing old air in said tobacco stack out of said plastic sealing tent via said inlet control joint and said outlet control joint on the other side of said plastic sealing tent, until column concentration of nitrogen in said plastic sealing tent is above 85%, at this time switching off said nitrogen generator, said inlet control joint and said outlet control joint on said sealing tent of said tobacco stack, manually introducing phosphine into said sealed tobacco stack, until volume concentration thereof is 30-700 ppm, so that finally in said sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of phosphine is 30-700 ppm;

e) fumigation combining nitrogen with sulfuryl fluoride: connecting said inlet control joint and said outlet control joint on one side of said plastic sealing tent with said nitrogen generator via said ventilating pipe, keeping said inlet control joint and said outlet control joint on said sealing tent, and a valve on said connection pipe at an “on” state, introducing nitrogen into said tobacco stack via positive pressure of said nitrogen generator, and forcing old air in said tobacco stack out of said plastic sealing tent via said inlet control joint and said outlet control joint on the other side of said plastic sealing tent, until column concentration of nitrogen in said plastic sealing tent is above 85%, at this time switching off said nitrogen generator, said inlet control joint and said outlet control joint on said sealing tent of said tobacco stack, manually introducing sulfuryl chloride into said sealed tobacco stack, until volume concentration thereof is 50-700 ppm, so that finally in said sealed tobacco stack, volume concentration of nitrogen is greater than 85%, and that of sulfuryl fluoride is 50-700 ppm;

and the dehumidification is carried out according to step f), g), h), or a combination thereof:

f) single-direction blowing and dehumidification: connecting said inlet control joint and said outlet control joint on one side of said plastic tent of said tobacco stack with an air outlet of said dehumidifier via a ventilating pipe, switching on said inlet control joint, said outlet control joint, said valve on said connection pipe, and said dehumidifier, and simultaneously on said inlet control joint and said outlet control joint on the other side of said plastic sealing tent of said tobacco stack, whereby blowing and dehumidifying said sealed space of said tobacco stack in a single direction, fresh air is gradually introduced and used to replace old and humid air in said tobacco stack, until relative air humidity in sealed space formed by said plastic sealing tent and said plastic film is less than 65%;

g) circulating dehumidification: connecting said inlet control joint and said outlet control joint on one side of said plastic sealing tent with an outlet pipe of said dehumidifier, connecting said inlet control joint and said outlet control joint on the other side of said plastic sealing tent with a return-air pipe of said dehumidifier, switching on said inlet control joint, said outlet control joint, and said valve on said connection pipe, and thus a power-saving circulating dehumidification system combining blowing with air returning is formed, until air humidity in said sealed space formed by said plastic sealing tent and said plastic film is less than 65%;

h) mechanical ventilation, dehumidification, and removal of accumulated heat of a centrifugal fan in a single direction: connecting said inlet control joint and said outlet control joint on one side of said plastic sealing tent to said blower or said centrifugal exhauster via said main ventilating pipe, switching on said inlet control joint and said outlet control joint on the other side of said plastic sealing tent, and said blower or said centrifugal exhauster, and performing single-direction blowing or exhausting whereby removing accumulated heat and humidity in said sealed space formed by said plastic sealing tent and said plastic film when air temperature in said plastic sealing tent is greater than that outside said plastic sealing tent, or if temperature of said tobacco stack abnormally rises.

2. The method of claim of claim 1, wherein the phosphine is used as the fumigant for prevention of pests in the tobacco leaves according to the following step a) or b):

a) using aluminum phosphide or magnesium phosphide for fumigation, switching off said inlet control joint and said outlet control joint on said plastic sealing tent, calculating dosage of aluminum phosphide or magnesium phosphide to dosage of 1-8 g/m³, and finally putting reagent into sealed space surrounded by said plastic sealing tent and keeping it at a sealed state;

b) combining phosphine with carbon dioxide for fumigation, switching off said inlet control joint and said outlet control joint on said plastic sealing tent, calculating dosage of aluminum phosphide required by said plastic sealing tent according to dosage of 0.5-3 g/m³, and amount of carbon dioxide required by said plastic sealing tent according to dosage of 10-50 g/m³, intensively mixing phosphine generated by carbon dioxide and aluminum phosphide in a steel cylinder, and injecting phosphine into said sealed space surrounded by said plastic sealing tent via an applicator, volume concentration of phosphine being 30-700 ppm, and sealed state of said plastic tent kept for more than three days.

3. The method of claim 1, wherein after fumigation combining nitrogen with phosphine or fumigation combining nitrogen with sulfuryl fluoride, said inlet control joint and said outlet control joint on one side of said plastic sealing tent are connected to an exhaust gas filtering and purifying device for fumigation via a main ventilating pipe, said centrifugal exhauster, and said inlet control joint and said outlet control joint on the other side of said plastic sealing tent are switched on whereby pumping out poisonous exhaust gas in said sealed space, and blowing said gas into said exhaust gas filtering and purifying device for fumigation for further filtering and purification.

4. The method of claim 1, wherein a number of the inlet control joints and the out control joints comprising the end covers is 1 to 30.

5. The method of claim 1, wherein the plastic sealing tent is made from plastic film or Nylon composite film.

6. The method of claim 1, wherein a volume concentration of the nitrogen is greater than or equal to 85%.

7. The method of claim 3, wherein the exhaust gas filtering and purifying device employs a poisonous gas filtering and purifying device, an absorption tower, an exhaust gas purification tower, a filtering device, a phosphine filtering and absorption device, a phosphine gas filtering device, a phosphine gas collector, a phosphine gas processing device, a phosphine gas purifying device, or a sulfuryl fluoride filtering and absorption device.