Method for storing tobacco

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.

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/m 3 , 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/m 3 , and amount of carbon dioxide required by said plastic sealing tent according to dosage of 10-50 g/m 3 , 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.