Process and apparatus for treating bulk commodities

Claim 2

An installation for fumigating a commodity with phosphine gas, comprising an enclosed storage space for accommodating the commodity, the commodity occupying part of the space, a gas space portion above the commodity, occupying another part of the space, an inlet for introducing gas into the space, an outlet duct connected to the gas space portion, including a gas flow induction means and discharge passage means associated with a phosphine gas absorption or destruction means adapted to remove phosphine from gas withdrawn from the gas space portion before such gas is released to the atmosphere.

Claim 3

An installation according to claim 1, wherein the inlet is adapted to introduce ambient air into the space in lieu of phosphine-containing gas withdrawn from the space.

Claim 4

Installation according to claim 1, wherein the gas flow induction means is also adapted by virtue of control means to optionally blow gas into the space.

Claim 5

Installation according to claim 1, wherein the gas flow induction means is connected to ducts adapted to optionally, by virtue of control means, recycle gas withdrawn from the gas space into the enclosed storage space.

Claim 6

Installation according to claim 1, wherein the duct means are adapted to recycle the gas into the commodity.

Claim 7

Installation according to claim 1, wherein the gas flow induction means is connected to induce through the commodity a flow of gas comprising a pesticidal concentration of phosphine gas and an elevated concentration of extraneously introduced CO 2 , adapted to enhance the pesticidal effect of the phosphine gas.

Claim 8

Installation according to claim 1, wherein the gas flow induction means is connected to induce the flow into and through the commodity from a source of phosphine and carbon dioxide located outside of the commodity.

Claim 9

Installation for fumigating a commodity with phosphine gas, comprising an enclosed storage space for accommodating the commodity, an inlet for introducing gas into the space and into the commodity, connected or adapted to be connected to a source of phosphine and carbon dioxide, located outside of the commodity, an outlet for withdrawing gas from the enclosed storage space and gas flow induction means adapted to induce a flow of the gas including phosphine and carbon dioxide through the commodity.

Claim 10

Installation for fumigating a commodity with phosphine gas, comprising an enclosed storage space for accommodating the commodity, an inlet for introducing gas into the space and into the commodity, connected or adapted to be connected to a source of phosphine and carbon dioxide, located outside of the commodity, an outlet for withdrawing gas from the enclosed storage space and gas flow induction means adapted to induce a flow of the gas including phosphine and carbon dioxide through the commodity.

Claim 11

Installation according to claim 1, wherein the outlet, the flow induction means and the inlet form one leg of a circulation loop for the gas, the other leg comprising the commodity in the space.

Claim 12

Installation according to claim 1, wherein the flow induction means are connected to means to discharge gas from the space and means to introduce ambient air into the space.

Claim 13

Installation according to claim 1, including phosphine absorption or destruction means connected such as to remove phosphine from the gas being discharged.

Claim 14

In a process for treating with phosphine gas a bulk commodity infested with or susceptible to infestation by pests, while stored or transported in a closed space by the controlled hydrolysis of a suitable hydrolysable metal phosphide over a period of about 1.25 to 20 days so as to generate phosphine gas in a manner such that the phosphine gas spreads through the entire bulk commodity and is maintained therein in a concentration and for a duration adapted to destroy such pests as are present in the bulk commodity, the improvement wherein the bulk commodity is fumigated with a gas stream circulating therethrough which contains therein a lethal concentration of phosphine gas and which has extraneously introduced carbon dioxide therein in a concentration substantially higher than the atmospheric CO 2 content.

Claim 15

In a process for treating with phosphine gas a bulk commodity infested with or susceptible to infestation by pests, while stored or transported in a closed space by the controlled hydrolysis of a suitable hydrolysable metal phosphide over a period of about 1.25 to 20 days so as to generate phosphine gas in a manner such that the phosphine gas spreads through the entire bulk commodity and is maintained therein in a concentration and for a duration adapted to destroy such pests as are present in the bulk commodity, the improvement wherein the bulk commodity is fumigated with a gas stream circulating therethrough which contains therein a lethal concentration of phosphine gas and which has extraneously introduced carbon dioxide therein in a concentration substantially higher than the atmospheric CO 2 content.

Claim 16

Process according to claim 1 wherein the phosphine is spread throughout the entire bulk commodity with air enriched with up to 30% CO 2 .

Claim 17

In a process for treating with phosphine gas, a bulk commodity infested with or susceptible to infestation by pests, while stored or transported in a closed space, the improvement which comprises withdrawing a gas comprising phosphine and carbon dioxide from a source or sources located outside of the commodity and introducing and circulating the gas into and through the commodity in a manner such that the gas spreads through the entire bulk commodity and is maintained therein in a lethal concentration and for a duration adapted to destroy such pests as are present in the bulk commodity, the gas comprising extraneously introduced carbon dioxide in a concentration substantially higher than the atmospheric CO 2 content.

Claim 18

In a process for treating with phosphine gas, a bulk commodity infested with or susceptible to infestation by pests, while stored or transported in a closed space, the improvement which comprises withdrawing a gas comprising phosphine and carbon dioxide from a source or sources located outside of the commodity and introducing and circulating the gas into and through the commodity in a manner such that the gas spreads through the entire bulk commodity and is maintained therein in a lethal concentration and for a duration adapted to destroy such pests as are present in the bulk commodity, the gas comprising extraneously introduced carbon dioxide in a concentration substantially higher than the atmospheric CO 2 content.

Claim 19

Process according to claim 1, wherein the phosphine is spread throughout the entire bulk commodity with air enriched with up to 30% CO 2 .

Claim 20

Process according to claim 1, wherein the gas is eventually withdrawn from the closed space and subjected to destruction or absorption of phosphine before being released to the atmosphere.

Claim 21

Process according to claim 1, wherein the phosphine is generated at the source by hydrolysis of a hydrolysable metal phosphide and the gas is caused to circulate at a rate and time or times adapted to the rate of phosphine gas generation and so as to avoid excessive concentration build-up of phosphine, and wherein the gas circulation is initiated in response to a predetermined difference between the phosphine concentration at two localities.

Claim 22

In an apparatus for treating with phosphine a bulk commodity infested with or susceptible to infestation comprising a closed storage space adapted for containing a bulk commodity, means for releasing phosphine gas into bulk commodity stored in the storage space, means for inducing a closed loop gas flow through the bulk commodity stored in the storage space, in a path which travels through the region of phosphine gas release into the bulk commodity to an area of the bulk commodity remote and opposite therefrom and then back along a separate return path to the region of phosphine gas release, and a timing device programmed to (i) commence the gas flow before the phosphine concentration in a zone adjoining the region of phosphine gas release rises above a preselected limit which is well below the auto-ignition limit for the phosphine gas; (ii) maintain the gas flow at a concentration reducing rate at least until the concentration in that zone has dropped to a second low value which at most is approximately equal to the average concentration of phosphine gas throughout the closed space; and (iii) repeat the gas flow for as often and as long as is necessary to prevent a rise in phosphine concentration in that zone above the auto-ignition limit, directly or indirectly on the basis of operating parameters which determine the phosphine concentrations at given times in a zone adjoining the region of phosphine gas release and in other parts of the closed space, the improvement that the apparatus is programmed to initiate the gas flow in response to a predetermined difference between the phosphine concentration at two localities of the apparatus.

Claim 23

In an apparatus for treating with phosphine a bulk commodity infested with or susceptible to infestation comprising a closed storage space adapted for containing a bulk commodity, means for releasing phosphine gas into bulk commodity stored in the storage space, means for inducing a closed loop gas flow through the bulk commodity stored in the storage space, in a path which travels through the region of phosphine gas release into the bulk commodity to an area of the bulk commodity remote and opposite therefrom and then back along a separate return path to the region of phosphine gas release, and a timing device programmed to (i) commence the gas flow before the phosphine concentration in a zone adjoining the region of phosphine gas release rises above a preselected limit which is well below the auto-ignition limit for the phosphine gas; (ii) maintain the gas flow at a concentration reducing rate at least until the concentration in that zone has dropped to a second low value which at most is approximately equal to the average concentration of phosphine gas throughout the closed space; and (iii) repeat the gas flow for as often and as long as is necessary to prevent a rise in phosphine concentration in that zone above the auto-ignition limit, directly or indirectly on the basis of operating parameters which determine the phosphine concentrations at given times in a zone adjoining the region of phosphine gas release and in other parts of the closed space, the improvement that the apparatus is programmed to initiate the gas flow in response to a predetermined difference between the phosphine concentration at two localities of the apparatus.

Claim 24

Apparatus according to claim 1, comprising gas circulating pipe means fitted with flow induction means for creating a closed loop gas circuit through the storage space, including a return leg of the loop external from the bulk commodity and further comprising valve means adapted for conveying atmospheric air into the commodity and for discharging the phosphine-containing gas contained in the circuit into the atmosphere.

Claim 25

Apparatus according to claim 1, wherein the means for discharging the phosphine-containing gas include phosphine destruction or absorption means adapted for removing phosphine from the phosphine-containing gas before discharge into the atmosphere.

Claim 26

In a process for treating with phosphine gas a bulk commodity infested with or susceptible to infestation by pests, while stored or transported in a closed space by the controlled hydrolysis of a suitable hydrolysable metal phosphide over a period of about 0.25 to 20 days so as to generate phosphine gas in a manner such that the phosphine gas spreads through the entire bulk commodity and is maintained therein in a concentration and for a duration adapted to destroy such pests as are present in the bulk commodity, the improvement wherein the bulk commodity is fumigated with a gas stream circulating therethrough which contains therein a lethal concentration of phosphine gas and which has extraneously introduced carbon dioxide therein in a concentration substantially higher than the atmospheric CO 2 content.

Claim 27

In a process for treating with phosphine gas a bulk commodity infested with or susceptible to infestation by pests, while stored or transported in a closed space by the controlled hydrolysis of a suitable hydrolysable metal phosphide over a period of about 0.25 to 20 days so as to generate phosphine gas in a manner such that the phosphine gas spreads through the entire bulk commodity and is maintained therein in a concentration and for a duration adapted to destroy such pests as are present in the bulk commodity, the improvement wherein the bulk commodity is fumigated with a gas stream circulating therethrough which contains therein a lethal concentration of phosphine gas and which has extraneously introduced carbon dioxide therein in a concentration substantially higher than the atmospheric CO 2 content.

Claim 28

The process according to claim 1, wherein after fumigation has been completed, a stream of atmospheric air is introduced into the bulk commodity and the phosphine-containing gas thereby displaced therefrom is passed into phosphine destruction or absorption means adapted for removing phosphine from the phosphine-containing gas prior to the gas being discharged into the atmosphere.

Claim 29

Apparatus adapted for treating with phosphine gas a bulk commodity infested with or susceptible to infestation by pests, while being stored or transported in a closed space, such as a bulk container, a bulk storage or transportation vessels or bin, silo, shiphold, bulk transport railway or road truck in which phosphine gas, produced by the controlled hydrolysis over a period of about 0.25 to 20 days of a suitable hydrolyzable metal phosphide, is released into at least one region of the bulk commodity, is spread throughout the entire bulk commodity, and is maintained therein in a concentration and for a duration effective to destroy any pests in the bulk commodity, the improvement which comprises means for inducing a closed loop gas flow for the phosphine gas in a path through the bulk commodity which travels through the region of phosphine gas release towards a region of the bulk commodity remote and opposite therefrom and then back to the region of release along a separate return path, the gas flow being (i) commenced before the phosphine concentration in a zone adjoining the region of the phosphine gas release rises above a preselected limit which is substantially below the auto-ignition limit for the phosphine gas (ii) maintained at a concentration reducing rate at least until the concentration in that zone has dropped to a second lower value which at most is approximately equal to the average concentration of phosphine gas throughout the closed space; and (iii) repeated for as often and as long as is necessary to prevent a rise in phosphine concentration in that zone above the auto-ignition limit, the circulation of the gas through the loop being adjusted at given times based on the concentration of phosphine gas at those times in the zone adjoining the region of phosphine gas released and the average concentration of phosphine gas throughout the closed space, said apparatus comprising gas circulating pipe means fitted with blower means for creating a closed loop gas circuit through the storage space, including a return leg of the loop external from the bulk commodity and further comprising valve means adapted for conveying atmospheric air into the commodity and means for discharging the phosphine-containing gas contained in the circuit into the atmosphere which include phosphine destruction or absorption means adapted for removing phosphine from the phosphine-containing gas before discharge into the atmosphere.

Claim 30

Apparatus adapted for treating with phosphine gas a bulk commodity infested with or susceptible to infestation by pests, while being stored or transported in a closed space, such as a bulk container, a bulk storage or transportation vessels or bin, silo, shiphold, bulk transport railway or road truck in which phosphine gas, produced by the controlled hydrolysis over a period of about 0.25 to 20 days of a suitable hydrolyzable metal phosphide, is released into at least one region of the bulk commodity, is spread throughout the entire bulk commodity, and is maintained therein in a concentration and for a duration effective to destroy any pests in the bulk commodity, the improvement which comprises means for inducing a closed loop gas flow for the phosphine gas in a path through the bulk commodity which travels through the region of phosphine gas release towards a region of the bulk commodity remote and opposite therefrom and then back to the region of release along a separate return path, the gas flow being (i) commenced before the phosphine concentration in a zone adjoining the region of the phosphine gas release rises above a preselected limit which is substantially below the auto-ignition limit for the phosphine gas (ii) maintained at a concentration reducing rate at least until the concentration in that zone has dropped to a second lower value which at most is approximately equal to the average concentration of phosphine gas throughout the closed space; and (iii) repeated for as often and as long as is necessary to prevent a rise in phosphine concentration in that zone above the auto-ignition limit, the circulation of the gas through the loop being adjusted at given times based on the concentration of phosphine gas at those times in the zone adjoining the region of phosphine gas released and the average concentration of phosphine gas throughout the closed space, said apparatus comprising gas circulating pipe means fitted with blower means for creating a closed loop gas circuit through the storage space, including a return leg of the loop external from the bulk commodity and further comprising valve means adapted for conveying atmospheric air into the commodity and means for discharging the phosphine-containing gas contained in the circuit into the atmosphere which include phosphine destruction or absorption means adapted for removing phosphine from the phosphine-containing gas before discharge into the atmosphere.