WO2006116809A1 - Procédé d’enlèvement de gaz résiduel amélioré - Google Patents

Procédé d’enlèvement de gaz résiduel amélioré Download PDF

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Publication number
WO2006116809A1
WO2006116809A1 PCT/AU2006/000570 AU2006000570W WO2006116809A1 WO 2006116809 A1 WO2006116809 A1 WO 2006116809A1 AU 2006000570 W AU2006000570 W AU 2006000570W WO 2006116809 A1 WO2006116809 A1 WO 2006116809A1
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WO
WIPO (PCT)
Prior art keywords
gas
enclosure
residual
container
residual gas
Prior art date
Application number
PCT/AU2006/000570
Other languages
English (en)
Inventor
Kenneth George Brash
Original Assignee
Asiaworld Shipping Services Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2005902207A external-priority patent/AU2005902207A0/en
Application filed by Asiaworld Shipping Services Pty Ltd filed Critical Asiaworld Shipping Services Pty Ltd
Publication of WO2006116809A1 publication Critical patent/WO2006116809A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3409—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor

Definitions

  • the present invention relates generally to a method for removing a residual gas from matter (eg. goods) placed in an enclosure.
  • the invention will primarily be described with reference to its use in removing a residual gas from cargo such as timber dunnage, crates, pallets and other porous bulk materials, but the invention can have broader application to other bulk materials such as grain, foodstuffs, fruit and vegetables and the like.
  • recently painted, enamelled or laguered items such as furniture, vehicles or other articles can emit noxious smells or fumes over time.
  • the gases or vapours generated can pose an environmental exposure risk and possibly overpower or poison persons who may access the goods after storage.
  • certain agricultural goods for example, rice, grain, seeds, corn cobs and stalks
  • furnigant when being subjected to fumigation to destroy pests such as parasites and insects etc.
  • the fumigant can des ⁇ rb and become trapped in the interstices between the agricultural goods, posing an environmental and workplace hazard.
  • residual gas refers to any measurable quantity of gases, fumes or vapours remaining, or generated, in an enclosed chamber, the chamber having been sealed for a period of time.
  • conventional shipping container refers to the commonly used containers of varying lengths and heights (for example 40-foot length or 20-foot length containers) , well known in the cargo shipping and rail transportation industries. These containers normally are made of metal with corrugated side walls and an outwardly openable double door located at one end of the container for access thereinto.
  • the present invention provides a method for removing a residual gas that is associated with matter located in an enclosure, t ⁇ ie enclosure adapted for use with a gas extraction means, the method comprising the steps of.:
  • the method can further comprise repeating the abovementioned steps (b) and (c) in sequence, perhaps for a number of- times to maximise the yield of residual gas extracted.
  • the method step of extracting at least some of the residual gas can involve selectively actuating the gas extraction means.
  • the gas extraction means can be operated continuously.
  • the method can further comprise the steps of : providing a gas inlet means that is operatively coupled to the enclosure in use; and
  • the flushing gas can be a gas which is recirculated from the gas extraction means and from which the residual gas has been wholly or partly captured and removed.
  • the flushing gas may be at least in part made up of atmospheric air.
  • the flow of flushing gas can be initiated and, in some embodiments, the gas pressure in the enclosure increased.
  • the total pressure of gases within the enclosure can be monitored and controlled, for example using pressure gauges and manual valves, or an automated control system of some type.
  • the concentration of residual gas in the enclosure can be monitored, for example by using a gas detection meter.
  • a gas detection meter allows an operator to know whether the concentration of residual gas is at safe levels so that the enclosure may be accessed by workers, or whether the gas extraction step has satisfactorily lowered the amount of residual gas present in the enclosure,
  • the method further comprises the step of capturing and/or decomposing at least part of the residual gas extracted from the enclosure. In other embodiments, substantially all of the extracted residual gas ie captured and/or decomposed.
  • captured residual gas can be absorbed/adsorbed into/onto a capture means, for example a solid for absorption/adsorption of gases.
  • the method can then further comprise the step of washing the capture means to remove captured residual gas.
  • the method can comprise the step of decomposing the residual gas on the capture means by use of a chemical reagent.
  • the residual gas can be reacted with a capture means to become decomposed, for example by a chemical reaction.
  • the residual gas can be captured in a solution.
  • This method can then further comprise the step of treating the solution to decompose the captured residual gas, for example by a chemical reaction.
  • a majority of the residual gas present in the enclosure can be extracted.
  • the present invention provides a residual gas removal apparatus arranged to be operatively coupled to an enclosure for removing residual gas from inside the enclosure, the apparatus comprising: a gas extraction means for extracting gas from the enclosure; a gas inlet for introducing a flushing gaa into the enclosure and/or for returning extracted gas into the enclosure; and controlling means for controlling the flow of gases through at least one of the gas inlet and gas extraction means,- wherein the gas inlet and gas extraction means are arranged at or adjacent respective distal end regions of the enclosure to facilitate movement of gas from one end region to another in use.
  • a gas extraction means for extracting gas from the enclosure
  • a gas inlet for introducing a flushing gaa into the enclosure and/or for returning extracted gas into the enclosure
  • controlling means for controlling the flow of gases through at least one of the gas inlet and gas extraction means,- wherein the gas inlet and gas extraction means are arranged at or adjacent respective distal end regions of the enclosure to facilitate movement of gas from one end region to another in use.
  • end regions can also refer to regions that are adjacent to opposing sides of a rounded, circular or spherical enclosure, and not just to regions near opposing walls of a square or rectangular enclosure.
  • the gas extraction means and the gas inlet can be placed in fluid communication by a conduit that is locatable external of the enclosure in use.
  • at least part of the conduit is arranged to be mounted to an exterior of the enclosure .
  • the controlling means can comprise a baffle internally located in the conduit to slow the movement of gas therewithin.
  • Other gas flow restriction devices are also possible, such as Venturis or orifice plates .
  • controlling means can comprise a variable speed controller for the gas extraction means, for example where the gas extraction means is in the form of a variable speed fan.
  • a controlling means can be additional to the use of a baffle or other flow restriction type controlling means located in the conduit.
  • a gaa capture and/or decomposition means may be arranged in fluid communication with the gas extraction means for respective capture and/or decomposition of at least some residual gas extracted from the enclosure.
  • the gaa capture means comprises a solid for absorbing/adsorbing residual gas.
  • the solid can be present in an absorption/ adsorption bed to which at least part of the extracted residual gas attaches.
  • One example solid is activated carbon.
  • the captured gas can then be further treated to be decomposed, for example by a chemical reaction.
  • the gas decomposition means can comprise a solid for reacting with residual gas so that the gas is decomposed by a chemical reaction.
  • the gas capture means can comprise a solution for capturing residual gas, for example an aqueous solution.
  • the solution can then be further treated to decompose the captured residual gas, for . example by a chemical reaction.
  • the enclosure can be defined by a conventional shipping container.
  • the present invention provides a method for removing a residual gas that is associated with matter located in an enclosure, the enclosure adapted for use with a gas heating means and a gas extraction means, the method comprising the steps of: (a) heating at least some of the residual gas present via the gas heating means such that the temperature in the enclosure reaches a temperature that is more than atmospheric temperature outside the enclosure;
  • Such a method allows a high degree of efficiency for the extraction of residual gases, which are initially absorbed into or adsorbed at the surface of matter that is placed inside the enclosure.
  • the net tendency is for the residual gases to be warmed and to desorb with maximum yield and rate from small holes and/or pores in the matter.
  • the method can further comprise repeating the abovementioned steps (c) and (d) in sequence, perhaps for a number of times to maximise the yield of residual gas extracted.
  • the temperature of gases within the enclosure can be monitored and controlled.
  • the steps of the method are otherwise as outlined for the first aspect.
  • the present invention provides a residual gas removal apparatus arranged to be operatively coupled to an enclosure for removing residual gas from inside the enclosure, the apparatus comprising; a gas extraction means for extracting gas from the enclosure; a gas heating means for heating gas extracted from or located within the enclosure;
  • a gas inlet for introducing a flushing gas into the enclosure and/or for returning extracted gas into the enclosure; and a controlling means for controlling the gas heating means ; wherein the gas heating means is arranged at, adjacent to or within the enclosure to facilitate heating of gas in use.
  • Such an. apparatus permits a high degree of efficiency for the extraction of residual gases, which are initially associated with matter that is placed inside the enclosure.
  • the temperature of gases within the enclosure By controlling the temperature of gases within the enclosure to higher than the atmospheric temperature in the local area outside the enclosure, the desorption of residual gases from the matter located in the enclosure can be accelerated.
  • the gas heating means can be placed in fluid communication with a conduit that is loeatable external of the enclosure in use. In other embodiments, the gas heating means can be located entirely within the enclosure .
  • the gas heating means may be an electric or a combustion heater.
  • the flow of flushing gas can be initiated and, in some embodiments, the gas temperature in the enclosure decreased.
  • the apparatus is otherwise as outlined for the second aspect.
  • Figure '1 shows- a right side view of a shipping container fitted with a residual gas removal apparatus in accordance with one embodiment of the invention
  • Figure IA shows an end view of the shipping container of Figure 1 when fitted with the residual gas removal apparatus ;
  • Figure 2 shows a schematic block flow diagram of one embodiment of a residual gas removal method when configured to remove residual gas and create a sub-atmospheric gas pressure, in accordance with one embodiment of the invention,-
  • Figure 3 shows the schematic block flow diagram of Figure 2 when configured to remove residual gas and to provide a return flushing gas flow into the enclosure
  • Figure 4 shows the schematic block flow diagram of ' Figure 2 when not configured to remove residual gas from the enclosure, but only to vent the enclosure.
  • a residual gas removal apparatus is shown in Figures 1 and 1A which is arranged for removing residual gas from matter placed inside an enclosure.
  • the enclosure is shown in the form of a conventional shipping container 10, although in other embodiments the enclosure can be in other forms, for example a silo, a shed, warehouse and rooms of any dimension capable of being depreasurised or heated as necessary.
  • the enclosure can also be in the form of a purpose-built fumigation' chamber (for example made of concrete or bricks) or a converted cool room. Any structure that is made of appropriate materials that are capable of housing and withstanding depressurisation or heating (of the magnitude that will shortly be described) will be suitable .
  • the container end wall -12 has a hole 14 which is fitted with protruding pipe 16 to which a gas extraction means is operatively coupled.
  • the gas extraction means shown is in the form of a flexible hose pipe 18 which is in fluid communication with a suction fan 20, which is itself mounted onto a platform 22 which is located on surrounding ground 24.
  • a suction fan can be located on an adjacent service vehicle, for example.
  • the hole 14 and protruding pipe 16, via which gases are extracted from the container 10 in use are located in the lower region of the end wall 12. This is typically where the heavier than air toxic gas molecules used in fumigation (for example methyl bromide) will naturally concentrate without recirculation.
  • the gas extraction means also includes a butterfly valve 26 fitted to the protruding pipe IS, the butterfly valve 26 being directly connected to the flexible hose pipe 18.
  • the connection of such a valve at the outlet or another flow restriction device at a gas inlet to the container permits an operator to regulate the gag pressure in the interior- of the container 10, as will shortly be described.
  • the auction fan 20 is connected via a flexible pipe 28 to an absorption/adsorption means. in the . form of an absorption/adsorption bed 30.
  • the bed 30 comprises a cylindrical housing 34 which is packed with activated carbon particles that are located in a cartridge.
  • the extracted gases flow from the suction fan 20 via the flexible hose pipe 28 into a lower region of the housing 34, and exit via a neck 38 located at a hole 40 at the uppermost peaked cap 42 of the housing 34.
  • at least some of the extracted residual gas attaches at the surfaces of the activated carbon particles and in the pores of the carbon.
  • the toxic gas molecules found in the residual gaaes can be entirely stripped from the flow of gas that is extracted from the container 10 by the suction fan 20.
  • the remaining gases flow back to the container 10 via the hole 40, neck 38 and a flexible hose line 44 which is coupled by a hose coupling 46 to the neck 38.
  • the opposing end of the flexible hose line 44 is directly coupled to a T-piece conduit 47 by a connector 45.
  • the remaining two arms of the T-piece are each fitted with a butterfly valve 48, 49.
  • One such butterfly valve 48 is mounted to the end of a gas return line.
  • the gas return line shown is in the form of a rigid gas return pipe 50 that is mounted on brackets 52 that are spaced along the exterior of both the end wall 12 and the roof 54 of the container 10.
  • the other butterfly valve 49 is also connected to a further rigid pipe that is mounted to the end wall 12 of the container 10, and which extends vertically above the container 10 for use as a gas ventilation stack 56.
  • the apparatus in use can direct extracted gases that have passed through the absorption/adsorption bed 30, to flow to the gas return pipe 50 for return into the container 10 ⁇ if valve 49 is closed and valve 48 is open) , or to the gag ventilation stack 56 for expulsion to atmosphere (if valve 48 in closed and valve 49 is open) . If valves 48 and 49 are both open, then fresh air can enter into the container via the ventilation stack 56 and the gas return pipe 50 and be drawn into the container 10.
  • the rigid gas return pipe 50 is arranged to extend along the length of the container 10 and to terminate at a hole 58 which is located in the roof 54 of the container 10 to provide access to the container interior 59.
  • the gas return pipe 50 is arranged with a curved bend section S2 which is coupled to the roof hole 58.
  • the roof hole 58 and the end wall hole 14 are generally spaced apart at distal end regions of the container 10 in order to improve the cross-flow movement of gas within the container. This cross-flow avoids the incidence of freed residual gases not being extracted from the interior 59 of the container 10, where the freed residual gases are those gases that have been freed over time due to temperature or pressure variations within the container, and then become trapped in pockets or other small spaces between articles of cargo and packing materials .
  • a circulation fan housing 64 is positioned at the end wall 12 of the container 10 , and a cirpulation fan 66 is mounted therewithin.
  • the housing 64 protrudes from the end wall 12, and the circulation fan 66 is arranged to face inwardly toward the interior 59 of the container 10.
  • the circulation fan 66 can assist the general movement of gases within the container interior 59, and may reduce the incidence of freed residual gases being trapped in pockets within the cargo.
  • the circulation fan 66 may not be required, as the positive flow of gas through the container 10 by recirculation out of the end wall hole 14 for return back into the container via the roof hole 58 may be sufficiently strong for sufficient movement of residual gas to occur.
  • the gas return pipe 50 is arranged with an internally located baffle 70 which in use slows the movement of gas within the pipe 50.
  • other types of flow restriction can be used, such as a venturi, orifice plate etc. The location of such a flow restriction device permits regulation of the gas pressure in the interior of the container 10, and enables an operator to guide the gas pressure in the container 10 to a pressure that is less than the ambient atmospheric pressure outside of the container 10. This can be achieved by ensuring that the outlet butterfly valve 26 is fully open, but that the flow of gases being returned to the container 10 is restricted.
  • the auction fan can be a variable speed fan and so can be regulated by an operator
  • Such an apparatus can be used in conjunction with the baffle 70 or venturi, orifice plate etc,
  • the butterfly valves 48 and 49 can both be arranged in the open (or partially open) position to deliver a flow of at least some atmospheric air as a flushing gas into the container 10, via the gas ventilation stack 56 and into the gas return pipe 50, in situations where the pressure of the container interior needs to be raised back up to atmospheric pressure, or to cool the gas temperature in the container by introducing atmospheric air.
  • the atmospheric air inlet there is no necessity for the atmospheric air inlet to be located at or in fluid communication with the gas return pipe 50, and the same pressure raising and temperature lowering effect can be achieved by the use of a gas inlet port and valve which is located directly on a side wall or an end wall of the container, for example.
  • the shipping container 10 can also be fitted with pressure monitoring means in the form of a pressure gauge for monitoring the total pressure of gaaeB within the container 10.
  • a pressure gauge for monitoring the total pressure of gaaeB within the container 10.
  • the gauge can be mounted to a further hole in a wall of the container 10, with a pressure sensor device connected thereto that is located within the container 10.
  • the gauge can also be located in a pipe, for example the pipe 50.
  • the apparatus can also include a controlling means such as an electronic controlling system, for controlling the flow of gases through at least one of the gas inlet butterfly valve 48 and gas extraction butterfly valve 26 in response to the monitored pressure within the container.
  • a controlling means such as an electronic controlling system, for controlling the flow of gases through at least one of the gas inlet butterfly valve 48 and gas extraction butterfly valve 26 in response to the monitored pressure within the container.
  • the valves 26, 48 can be independently operated so that the monitored pressure in the container 10 can be allowed to fall below atmospheric pressure (such as by actuating the suction fan 20, whilst the gas inlet valve 48 remains partially open, or even closed) , or maintained at a pre-determined pressure value.
  • Such pressure control can permit the pressure in the container to be reduced below ambient atmospheric pressure levels so that gases absorbed in goods or packing that are located in the enclosure can be forced out of the pores etc S of the material/ or from the interstices between the materials/ and efficiently extracted from the enclosure with minimal risk to persons who may need to access ' the container during later unpacking of its contents.
  • gas capture and/or decomposition means When residual gases are extracted from the 0 container, other types of gas capture and/or decomposition means may be arranged for capture and/or decomposition of at least some of the residual gas to prevent venting to air
  • the residual gas which is extracted and absorbed/adsorbed or even decomposed, can also be of a different type than alkyl halides (such as methyl bromide) , for example, phosphine, sulfural fluoride or 0 carbon dioxide.
  • a gas decomposition means can comprise a solid for reacting with residual gas so that the gas is decomposed by a chemical reaction.
  • a chemical reaction for example, in the case of .sulfural fluoride, passing the gas through an 5 absorption cartridge containing calcium carbonate causes the gas to be converted to form various sulfur salts which again can be safely disposed of,
  • a gas capture means can comprise a solution for capturing residual gaa, for example 0 an aqueous solution.
  • a gas capture means can comprise a solution for capturing residual gaa, for example 0 an aqueous solution.
  • a solution for capturing residual gaa for example 0 an aqueous solution.
  • passing the gas through an absorption cartridge of wet carbon causes the gas to be converted to form phosphoric acid on the outside surface of the carbon.
  • This weak ' acid can be subsequently washed away from the carbon.
  • this gas may simply be removed from the container by bubbling into a vessel or cartridge containing water to form carbonic acid, and subsequently discarded.
  • this gas may simply be removed from the container by bubbling into a vessel or cartridge containing water to form carbonic acid, and subsequently discarded.
  • other absorbing or adsorbing materials may be equally suitable for this purpose (eg - zeolites, activated eartlh materials . etc) .
  • the absorption/adsorption bed can be periodically washed to remove the absorbed/adsorbed gases and regenerated for reuse, and the residual gas decomposed by a chemical reaction..
  • an activated carbon bed with absorbed/adsorbed methyl bromide fumigant can be washed with a solution of sodium thiosulphate to chemically decompose the methyl bromide and to yield one or more benign salts, such as sodium bromide and sodium methylthiosulphate.
  • Any of the gas capture and/or decomposition means described can be located on a service vehicle which in use is located adjacent to the container 10 and. which can receive the flow of gas from the suction fan 20. Such an arrangement ensures that at ' all times the extracted residual gases are quickly removed from the gas stream, which in turn ensures that a highly safe operating environment can be maintained with a low incidence of occupational health risk to operators.
  • the operator can keep the butterfly valve 48 closed initially and the butterfly valve 49 open whilst initiating a flow of residual gas out of the container 10 by actuating suction fan 20.
  • the gas contents of the container 10 are extracted via hole 14, pipe l ⁇ , butterfly valve 26 and flexible hose pipe IS to the fan 20, and eventually to the gas ventilation stack 56.
  • the pressure in the container can then fall by any fraction of atmospheric pressure until a pre-determined value is reached (Pl) , which is measured by a pressure gauge and sensor, for example.
  • Pl pre-determined value
  • the pressure can be lowered until the container side walls start to internally buckle and implode to a minor extent. Creaking sounds can be heard when this occurs .
  • the butterfly valve 49 is closed and the butterfly valve 48 is opened, (or partly opened) so that extracted gases are recir ⁇ ulated from the fan 20 via absorption/adsorption bed 30 and gas return pipe 50 back into the container 10.
  • the recirculated (or x flushing' ) gas has had all or at least part of the extracted residual gas removed therefrom during passage through the absorption/adsorption bed 30.
  • a flow of flushing gas which enters the container 10 via the gas return pipe 50 and hole 58, flushes the freed residual gases into the suction fan 20 and the absorption/adsorption bed 30.
  • P2 can be relatively higher than Pl or even the same as P1.
  • the suction fan 20 is switched off, and the low pressure (P2) in ' the container 10 is maintained for a predetermined interval without any flow of flushing gas being passed through the container.
  • This predetermined interval is also known as a "balancing" or standing time: In some instances the container 10 can also be entirely isolated by closing butterfly valves 26 and 48, although this may not ' be necessary.
  • the standing time at least some desorption of adsorbed and absorbed residual gases occurs from the material goods, when the net tendency is for the residual gases to desorb from small holes and/or pores in the goods (or from gaps or interstices between the goods) and be drawn into the low- pressure environment, of the interior 59 of the container 10.
  • the butterfly valve 26 is opened and the suction fan 20 ia then switched on, and the flow of residual gas out of the container 10 is resumed.
  • the flow of flushing gas being passed back into the container can also be. resumed if the butterfly valve 48 is also re-opened (as shown in Figure 3) .
  • This flow can carry out the residual gases that were desorbed during the balancing or standing time interval, and carry these gases for at least partial capture in the absorption/adsorption bed 30.
  • the pressure within the container 10 is not returned to atmospheric pressure levels, but is maintained at some sub- atmospheric level.
  • the pressure in the container can be maintained at one level (around P2) , or can even be further reduced by first closing the butterfly valve 48 and then opening the butterfly valve 49 during operation of the suction fan 20 (as shown in Figure 2) to reduce the pressure down to Pl, or even below.
  • the above- mentioned stepwise or pulsing procedure of an extraction interval followed by a "balancing" interval can be repeated multiple times to achieve maximum desorption of residual gases (all intervals being conducted at various sub- atmospheric pressures) ⁇
  • the steps . of extraction and balancing could readily be performed around two to ten times.
  • the selected length of the extraction and balancing time intervals used during each repetition can be varied, as can the pressures Pl and P2.
  • the suction fan 20 in order to move from a configuration where a flow of flushing gaa enters the container 10 to flush the freed residual gases out, and the predetermined interval where no flow of flushing gas occurs, it is not necessary to actuate the suction fan 20 between on and off, but instead the suction, fan can. be operated continuously, and may instead be taken "off-line” by simply closing the butterfly valves 26 and 48 and opening another gae entry valve (or bypass) into the fan 20 as well as opening valve 49 so that air is sucked into the fan 20 and vented to atmosphere, without actually needing to turn, the fan off.
  • the gas pressure in the enclosure can be increased back to atmospheric levels by opening up butterfly valve 49 and allowing air to be drawn into the interior 59 of the container 10 via ventilation stack 56 and gas return line 50 (as shown in Figure 4) .
  • an, operator may also be able achieve an effective removal of residual fumigant by varying the temperature in the enclosure rather than the pressure.
  • depressurising a particular material may be preferable to heating it, particularly if the material is perishable.
  • heating may be the preferred option.
  • the residual gases to be removed are known to be particularly volatile, a more effective release from the goods being treated may be able to be achieved through heating. A combination of heating and depressurisation is also possible.
  • the shipping container 10 already shown in the drawings can also be fitted with temperature monitoring means in the form of a thermocouple and temperature gauge for monitoring the total temperature of gases within the container 10.
  • temperature monitoring means in the form of a thermocouple and temperature gauge for monitoring the total temperature of gases within the container 10.
  • the thermocouple and temperature gauge can be mounted to a further hole in a wall of the container 10, with the thermocouple located within the container 10.
  • the apparatus can also include a controlling means such as an electronic controlling system, for controlling the operation of the heater and/or the flow of gases through at least one of the gas inlet butterfly valve 48 and gas extraction butterfly valve 26 in response to the monitored temperature within the container.
  • the heater 74 which is fully located within the container 10 can first be actuated to produce heat energy so that the monitored temperature in the container 10 rises' above ambient atmospheric temperature.
  • the heater 74 can be turned on and off by the operator or the temperature control system. Gases that are absorbed in goods or packing located in the enclosure will tend to gasify and be desorbed from, the pores and interstices etc of the those goods, allowing extraction of such gases from the enclosure with minimal risk to persons who may need to access the container during later unpacking of its contents.
  • the operation of the residual gas removal apparatus at elevated temperatures is similar to the operation already described when using elevated pressure conditions.
  • the operator actuates the heater 74 and opens the butterfly valve 48 whilst initiating a flow of residual gas out of the container 10 by actuating suction fan 20.
  • the gas contents of the container 10 are extracted via hole 14, pipe IS, butterfly valve 26 and flexible hose pipe 18. to the fan 20.
  • Extracted gases are then recirculated from the fan 20 via absorption/adsorption bed 30 and gas return pipe 50 back into the container 10. Again, the recirculated (or 4 flushing') gas has had all or at least, part of the extracted residual gas removed therefrom during passage through the absorption/adsorption bed 30.
  • the temperature inside the container can be stabilised at a level that is above the ambient atmospheric temperature outside of the container 10 by controlling the flow of recirculated gas and the operation of the heater 74, A flow of flushing gas, which enters the container 10 via the gas return pipe 50 and hole 58, flushes the freed residual gases into the suction fan 20 and the absorption/adsorption bed 30.
  • the temperature in the container can be raised, to any practical level until a pre-determined value is reached, as measured by the temperature gauge and sensor.
  • the suction fan 20 is switched off, and perhaps the heater is also switched off, or turned down.
  • the temperature in the container 10 is then maintained for a predetermined interval without any flow of flushing gas being passed through the container.
  • This pre-determined interval is also known as a "balancing" or standing time. During the standing time, at least some desorption of adsorbed and absorbed residual gases occurs from the material goods, when the net tendency is for the residual gases to volatilise and desorb from small holes and/or pores in the goods as a result of the higher- temperature environment of the interior 59 of the container 10, •
  • the suction fan 20 is then switched on, and the flow of residual gas out of the container 10 is resumed.
  • the flow of flushing gas being passed back into the container is also resumed (as shown in, Figure 3) .
  • This flow can carry out the residual gases that were- desorbed during the "balancing" or standing time interval, and carry these gases for at least partial capture in the absorption/adsorption bed 30.
  • the temperature within the container 10 is not reduced to the outside ambient atmospheric temperature levels, but is maintained at some level above the local atmospheric temperature. if required, the temperature in the container can be maintained at this one level, or can even be further increased by actuating the heater 74 and also restricting the recirculation flow of gases during operation of the suction fan 20 by partially closing butterfly valve 48.
  • the gas temperature in the enclosure can be lowered down again to ambient atmospheric levels by deactivating the heater 74 and opening up butterfly valve 49 and allowing air, to be drawn into the interior 59 of the container 10 via ventilation stack 56 and gas return line SO (as shown in Figure 4) .
  • a flow of flushing gas can be initiated via the ventilation stack 56, and the gas temperature in the enclosure decreased.
  • the temperature in a shipping container 10 on a cool day may be around 20 ° C.
  • An increase in the internal temperature in the container to around 30- 40 ° C has been shown to result in a significant increase in the removal of residual gases when using three repeated stepwise or pulsing procedures each comprising a 10 minute extraction interval followed by a 5 minute "balancing" or standing time interval.
  • the gas heating means can be present in other forms, and in other locations rather than inside the container 10.
  • electric, radiative or conductive heaters can be placed in fluid communication with the gas return pipe 50 that is external of the container 10.
  • Waste heat in the form of piped hot water, oil or steam can be arranged in proximity to the container or to the gas return pipe 50, for example, to convey heat energy into the residual gas removal apparatus.
  • the apparatus .and method ia adapted for use with a conventional shipping container or any type of enclosed space, and is relatively convenient and uncomplicated to operate;
  • the apparatus and method is relatively effective in removing residual gases from goods, and can be configured to operate at a number of pressures and temperatures to maximise gas extraction;
  • the apparatus and method is "environmentally friendly" in that any collected residual gases can be safely expelled or captured rather than be discharged into a workplace or populated environment consequently minimising the risk of gas exposure to persons who operate the apparatus, as well as to those persons who need to access the container itself during its later unpacking.
  • the apparatus and method reduces the incidence of subsequent slow desorption of residual gases during transportation to, or storage in, other locations, thus enhancing the personal safety of those who need to handle and/or use the goods later.
  • the gas return pipe does not need to be rigid, nor does it need to be mounted on top of the container but rather may be loosely placed along the side, or lower side wall/base edge, of the container.
  • the gas capture apparatus does not need to be located on a platform adjacent to the shipping container, but can be located on a mobile cart or other vehicle.
  • the invention need not be restricted to removal of residual fumigants such as methyl bromide, but can extend to the removal of any residual adsorbed gaseous substance which is undesirable or hazardous to human, or animal health.
  • the invention need not be restricted to the specific constructional features described, and may for example use a different type or size of shipping container, or another type of enclosure. Other types of valves, fans etc are also within the scope of the invention.
  • Blocks of pinewood were cut and the timber samples ware conditioned for two weeks at 25 ⁇ 2°C and 60% relative humidity in a constant temperature room. The blocks were then placed into a fumigation chamber to achieve, a volumetric loading ratio of 20-0%v/v.
  • Methyl bromide was then injected into the chamber and its concentration monitored by means of gas chromatography.
  • the initial dose was 48 g/m 3 of methyl bromide, which is the current Australian Quarantine Inspection Service (AQIS) recommended standard dose for wood fumigation.
  • AQIS Australian Quarantine Inspection Service
  • the concentration of methyl bromide multiplied by the time of exposure of the timber exceeded 400 g h/m 3 which AQIS indicates will give a 100% kill of most insect pests, at all development stages (see Table 1 for different pest types) .
  • a suction was- placed on the container until the pressure in the container reached 550 mm Hg (normal atmospheric pressure 760 ⁇ nm Hg) . This pressure was maintained by suction for 30 minutes and then the suction was turned off and the pressure in the container held at around that level for a 30 minute "balance interval" to permit desorption to occur- Suction was then introduced to maintain a sub-atmospheric pressure in the container of about 550 mm Hg and to withdraw some of the methyl bromide gas present therewithin. This suction was maintained for 30 minutes and then the suction was turned off and the pressure in the container held at around that level for a 30 minute "balance interval" to permit desorption to occur, and so on.
  • 550 mm Hg normal atmospheric pressure 760 ⁇ nm Hg
  • a suction was placed on the container until the pressure in the container reached 550 mm Hg (normal atmospheric pressure 760nm Hg) , This pressure was maintained by suction for 40 minutes and then the suction was turned off and the pressure in the container held at around that level for 20 minutes "balance interval" to permit desorption to occur. Suction was then introduced to maintain a sub-atmospheric pressure in the container of about 550 mm Hg and to withdraw some of the methyl bromide gas present therewithin. This suction was maintained for 40 minutes and then the suction was turned off and the pressure in the container held at around that level for a 20 minute "balance interval" to permit desorption to occur, and so on.
  • 550 mm Hg normal atmospheric pressure 760nm Hg
  • Experiment 3 The same experimental conditions as for Experiment 1 were conducted, except that the full 1 hour procedure was repeated 6 times. It was found that 99.5% of the methyl bromide had been released after this 6 hour procedure (the equivalent result was not achieved even after 2 days of "normal” or natural aeration in a fume cupboard) .

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Nutrition Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Polymers & Plastics (AREA)
  • Separation Of Gases By Adsorption (AREA)

Abstract

L’invention permet d’extraire des gaz résiduels de matériaux à l’aide d’une pression interne de conteneur qui est inférieure à la pression atmosphérique ambiante à l’extérieur du conteneur (10). Pour atteindre cet objectif, l’opérateur peut expulser un courant de gaz résiduel à partir du conteneur (10) en actionnant le ventilateur d’aspiration (20). La pression dans le conteneur (10) peut alors retomber d’une fraction quelconque de pression atmosphérique jusqu’à une valeur prédéterminée. Au bout d’un certain temps d’exploitation à la pression sub-atmosphérique, le ventilateur d’aspiration (20) est éteint, et la pression dans le conteneur (10) est maintenue pendant un intervalle prédéterminé sans faire passer de courant de gaz de purge à travers le conteneur (10). Cet intervalle prédéterminé est également connu comme “équilibrage” ou temps de séjour. Pendant le temps de séjour, au moins une certaine désorption de gaz résiduels adsorbés et absorbés se produit à partir des matériaux. Au terme de l’intervalle prédéterminé, l’expulsion de gaz résiduel à partir du conteneur (10) reprend. La pression dans le conteneur (10) ne revient pas aux niveaux de pression atmosphérique, elle est maintenue à un certain niveau sub-atmosphérique.
PCT/AU2006/000570 2005-05-02 2006-05-02 Procédé d’enlèvement de gaz résiduel amélioré WO2006116809A1 (fr)

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AU2005902207A AU2005902207A0 (en) 2005-05-02 An improved residual gas removal method
AU2005902207 2005-05-02

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Cited By (10)

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Publication number Priority date Publication date Assignee Title
EP2215907A2 (fr) 2009-02-10 2010-08-11 Dieter Wutzler Dispositif de modification de la composition du volume de gaz se trouvant dans l'espace intérieur d'un conteneur et procédé de modification de la composition
WO2011097671A1 (fr) * 2010-02-09 2011-08-18 Asiaworld Shipping Services Pty Ltd Portail à gaz pour structure et procédé pour son installation
WO2011103996A1 (fr) * 2010-02-26 2011-09-01 Frank Hertel Procédé d'aération de marchandises contaminées par des gaz nocifs, sas d'aération et installation à sas d'aération
WO2011103995A1 (fr) * 2010-02-26 2011-09-01 Frank Hertel Procédé d'aération de marchandises contaminées par des gaz nocifs, conteneur d'aération et installation d'aération
CN102295115A (zh) * 2010-06-24 2011-12-28 昆山中泓汽车零部件有限公司 集装箱熏蒸抽气装置
US8132357B2 (en) 2008-04-30 2012-03-13 Fred Rogacki Fumigation of containerized cargo
CN106628696A (zh) * 2017-01-16 2017-05-10 泸州品创科技有限公司 白酒储存控制挥发系统
EP3346831A4 (fr) * 2015-09-07 2019-05-22 Scrubbing Fumigants Pty Ltd Systèmes et procédés de fumigation
EP3527513A1 (fr) 2018-02-15 2019-08-21 Atmosafe BVBA Procédé et système pour libérer une unité de cargaison fermée pour le déchargement ou l'inspection
CN110946010A (zh) * 2019-10-23 2020-04-03 淮南市久祥米业有限公司 一种大米储存仓库

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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8132357B2 (en) 2008-04-30 2012-03-13 Fred Rogacki Fumigation of containerized cargo
DE102009008322A1 (de) 2009-02-10 2010-08-19 Dieter Wutzler Vorrichtung zum Ändern der Zusammensetzung des sich im Innenraum eines Containers befindlichen Gasvolumens und Verfahren zum Ändern der Zusammensetzung
DE102009008322B4 (de) * 2009-02-10 2010-12-09 Dieter Wutzler Vorrichtung zum Ändern der Zusammensetzung des sich im Innenraum eines Containers befindlichen Gasvolumens und Verfahren zum Ändern der Zusammensetzung
EP2215907A2 (fr) 2009-02-10 2010-08-11 Dieter Wutzler Dispositif de modification de la composition du volume de gaz se trouvant dans l'espace intérieur d'un conteneur et procédé de modification de la composition
US9872488B2 (en) 2010-02-09 2018-01-23 Asiaworld Shipping Services Pty Ltd Gas portal for a structure and method for installing the same
WO2011097671A1 (fr) * 2010-02-09 2011-08-18 Asiaworld Shipping Services Pty Ltd Portail à gaz pour structure et procédé pour son installation
CN102869586A (zh) * 2010-02-09 2013-01-09 亚洲环球运输服务有限公司 用于结构体的气体端口及其安装方法
WO2011103996A1 (fr) * 2010-02-26 2011-09-01 Frank Hertel Procédé d'aération de marchandises contaminées par des gaz nocifs, sas d'aération et installation à sas d'aération
WO2011103995A1 (fr) * 2010-02-26 2011-09-01 Frank Hertel Procédé d'aération de marchandises contaminées par des gaz nocifs, conteneur d'aération et installation d'aération
CN102295115A (zh) * 2010-06-24 2011-12-28 昆山中泓汽车零部件有限公司 集装箱熏蒸抽气装置
EP3346831A4 (fr) * 2015-09-07 2019-05-22 Scrubbing Fumigants Pty Ltd Systèmes et procédés de fumigation
CN106628696A (zh) * 2017-01-16 2017-05-10 泸州品创科技有限公司 白酒储存控制挥发系统
EP3527513A1 (fr) 2018-02-15 2019-08-21 Atmosafe BVBA Procédé et système pour libérer une unité de cargaison fermée pour le déchargement ou l'inspection
WO2019158433A1 (fr) 2018-02-15 2019-08-22 Atmosafe Bvba Procédé et système permettant de libérer une unité de rangement confinée pour le déchargement ou l'inspection
CN110946010A (zh) * 2019-10-23 2020-04-03 淮南市久祥米业有限公司 一种大米储存仓库

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