FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2006
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention- "AN IMPROVED APPARATUS FOR RAPID GENERATION OF PHOSPHINE GAS"
2. Applicant(s)
(a) NAME : United Phosphorus Ltd.
(b) NATIONALITY : Indian
(c) ADDRESS : Registered Office at 3-11, GIDC, Vapi- 396195, Gujarat and
Corporate Office at Uniphos House, 11th road, C.D.Marg, Khar (West), Mumbai - 400052, India
The following specification particularly describes the nature of this invention and the manner in which it is to be performed :-

Field of Invention:
The present invention relates to an improvement in the apparatus for continuous production of phosphine fumigant gas disclosed and claimed in Patent Application No. 593/BOM/1999 granted as Patent No. IN 196518.
More particularly, the present invention relates to an improved apparatus for rapid and continuous generation of phosphine gas having improved fumigation efficiency, economic significance and safe for industrial use without occurrence of fire or explosions over the apparatus disclosed and claimed in Patent No. IN 196518.
Background and prior art:
An apparatus for continuous production of Phosphine Fumigant Gas adjacent a silo or the like for direct delivery is disclosed and claimed in Patent No. IN 196518. Patent No. IN 196518 discloses the apparatus in its preferred form for continuous production of Phosphine fumigant gas comprising a reactor assembly consisting of an elongated reactor, metal phosphide inlet, and reactant gas inlet on one end and phosphine gas outlet on the other end of the reactor assembly, including an external heating jacket located between the said inlets and outlets, also including an external cooling jacket located between said elongated reactor and phosphine gas outlet, a delivery unit for delivery of particular metal phosphide to said reactor through said metal phosphide assembly for directing a stream of reactant gas containing a carrier gas and water to said reactor through said reactant gas inlet for reaction therein with said metal phosphide to produce Phosphine gas; and an output device for delivery of said phosphine gas from said reactor to said facility; a receiver operatively coupled with said reactor for receiving waste slurry therefrom, and for treating the slurry; a mobile frame including wheels attached thereto supporting said reactor assembly.


However, there exists a continuous need in the art for improved apparatus having improved method allowing the safe and rapid production of adequate quantities of phosphine gas to achieve pre-determined concentration for fumigation.
It has now been surprisingly found that the apparatus disclosed and claimed in Patent No. IN 196518 can be improved to produce phosphine gas in a rapid manner to attain the desired concentration of phosphine gas in the fumigation structure uniformly in a very short period of time. The generator further enables on-site generation of phosphine gas directly to an adjacent storage structure or commodity so that phosphine gas is directly delivered to the commodity or into the storage structure without intermediate storage in containers. Preferably, the generator is used to fumigate silos, stored grain, transport containers and ships. The present invention is directed to a rapid generation of phosphine gas, which ensures that the required amount of phosphine gas is released in a short interval of time of less than two hours.
A very common fumigation problem encountered with prior practices is the use of CO2, N2, argon, and other similar inert gases which aim to dilute the phosphine gas concentration and to maintain low levels of phosphine gas until the phosphine gas reaches the storage structure for fumigation.
At the same time, prior practices require an increased inventory and additional handling and hazards of pressurized cylinders.
There is accordingly a need in the art for an improved apparatus and safe method allowing the rapid production of phosphine gas for on-site generation. The desired apparatus and method would produce the desired phosphine gas concentration for fumigation while avoiding the need to produce phosphine gas at a remote site using intermediate containers of phosphine gas. Also, the apparatus that generated phosphine gas on a continuous basis without the addition of rotating parts like agitators, stirrers and rotors would be advantageous. Additionally, the improved apparatus or method would


also reduce or eliminate any hazards associated with the prior methods, including
eliminating the usage of inert gases.
The present invention affords an improved apparatus providing rapid production of
phosphine gas and further eliminating the usage of inert gases and having economic
significance without affecting the other advantages of the apparatus claimed in Patent No.
IN196518.
Object of the invention:
Therefore, it is an object of the present invention to provide an improvement in the apparatus claimed in Patent No. IN196518.
It is a further object of the present invention to provide an improvement particularly in rapid production of phosphine gas as disclosed and claimed in the Patent No. INI 96518.
It is also an object of the present invention to provide an improvement over the apparatus of Patent No. IN 196518 without affecting its other advantages such as continuous production of phosphine gas at the site of use so that desired phosphine concentration/time fumigation can be achieved rapidly and the like.
It is another object of the present invention to provide an improved apparatus for phosphine gas generation without making use of inert gases such as carbon dioxide, nitrogen, argon and the like.
It is yet another object of the present invention to provide an apparatus that generated phosphine gas rapidly without the addition of rotating parts like agitators, stirrers and rotors.
Additional object is to provide an improved apparatus or method that would reduce or eliminate any hazards associated with the prior methods.
Summary of the invention:


According to an aspect of the present invention there is provided an improvement in and relating to an apparatus claimed in Patent No. INI96518, said improved apparatus comprising,
a) a reaction pot with a supply of water to said reaction pot;
b) providing a supply of a metal phosphide to said reaction pot;
c) providing a predetermined quantity of agitation air to said reaction pot forming a reaction mixture;
d) agitating the said reaction mixture with a supply of agitation air tangentially at a turbulating pressure of 0.5-2 kg/cm2;
e) generating a predetermined quantity of phosphine gas upto 25,000 g in less than two hours where the reaction temperature not exceeding 60 degree C and
f) generating at least 50% of predetermined quantity of phosphine gas in 30 minutes;
g) diluting said phosphine gas with said supply of dilution air tangentially to the reaction pot thereby generating fumigant phosphine gas .
Detailed Description:
The present invention is broadly related to a generator and a corresponding method for fumigating a commodity, such as grain, with a phosphine gas. The generator and corresponding method are used to generate phosphine gas from a metal phosphide, preferably aluminum phosphide, magnesium phosphide and other similar phosphides. The generator and corresponding method to produce large quantities of phosphine gas in a rapid manner in a short period of time. The generator enables on-site generation of phosphine gas directly to an adjacent storage structure or commodity so that phosphine gas is directly delivered to the commodity or into the storage structure without intermediate storage in containers. Preferably, the generator is used to fumigate silos, stored grain, transport containers and ships. The present method is directed to a rapid generation of phosphine gas, which ensures that the required amount of phosphine gas is released in a short interval of time of less than two hours. Hence, the problem associated


with the existing generators of generating and delivering very small quantities in unit time are overcome.
The present invention provides a generator for the on-site generation of phosphine gas by directly delivering the phosphine gas to an adjacent commodity or storage structure in a uniform manner. The generator preferably includes a mobile frame supporting a reaction pot. The reaction pot doesn't have any rotating parts like agitators, stirrers, and rotors and hence, there is no wear and tear. In the reaction pot, a metal phosphide and water are added to produce a reaction mixture which is agitated with air to produce a phosphine gas. The agitation of the reaction mixture is accomplished by passing air under pressure through the reaction pot. The air produces turbulence which agitates or stirs the reaction mixture. The agitation air is added tangentially at a turbulating pressure of 0.5 to 2 Kg/cm2; generating a predetermined quantity of phosphine gas up to 25000 g in less than two hours. The reaction temperature does not raise above 60 degree C and generating 40% -50% of predetermined quantity of phosphine gas in 30 minutes; and diluting the generated phosphine gas by supplying adequate dilution air tangentially to the reaction pot.
No additional inert gases are needed to carry the phosphine gas for fumigation. Additional air, preferably from a storage structure, is used to dilute the phosphine gas in the preferred range of 100 to 5000 ppm and this fumigant phosphine gas is directly delivered to the commodity to be fumigated. Since ambient air is preferably circulated within the reaction pot for agitation and dilution, the temperature within the reaction pot can easily be maintained at a temperature near 55°C.
The generator also preferably contains a deactivation system for removing any unused reaction mixture and/or phosphine gas. The deactivation system primarily includes a secondary reactor which is connected to various air compressors and blowers ensuring that the unused reaction mixture is free from any active metal phosphide. Any phosphine gas from the reaction pot or unreacted fumigant phosphine gas is also cleaned preferably using an absorption tank. This eliminates any handling hazards to persons involved in processing the commodity since the operator is not exposed to the unreacted metal


phosphide.
Additionally, forced air circulation devices are used to evenly distribute the fumigant phosphine gas throughout the commodity to be fumigated. This greatly reduces the possibility of any localized increase in concentrate of phosphine gas which may lead to ignition or fire.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a flow diagram showing a preferred generator and method for making phosphine gas including a deactivation system containing a preferred secondary reactor and a preferred absorption tank;
FIG 2 is a graph showing rapid generation of 56 g of Phosphine gas according to the present invention
FIG 3 is a graph showing rapid generation of 7,500 g of Phosphine gas according to the present invention
FIG 4 is a graph showing rapid generation of 10000 g of phosphine gas according to the present invention
FIG 5 is a graph showing rapid generation of 25,000 g of phosphine gas according to the present invention
FIG 6: Slow generation of 500 g of phosphine gas at constant rate according to apparatus of IN196518


DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the preferred generator 10 for generating a phosphine gas. The generator 10 contains a reaction pot 12 for generating the phosphine gas. The reaction pot (12) size depends on the quantities of the phosphine to be generated from a few grams to 25 Kgs as per requirement. The reaction pot 12 does not contain rotating parts like agitators, stirrers and rotors. Hence, there is no friction which would lead to wear and tear of the reaction pot 12. Any mechanical stirring device has a normal wear and tear, which, with time will lead to phosphine gas leaking into atmosphere. This in turn becomes a health and safety hazard. A supply of a metal phosphide is fed to the reaction pot 12 via a metal phosphide input 14. The preferred metal phosphide is aluminum phosphide, magnesium phosphide and other similar phosphides. A predetermined quantity of a metal phopshide is taken to the said reactor pot. A supply of water is fed to the reaction pot via a reaction water input 16. Water and the metal phosphide are mixed in the reaction pot 12 to form a reaction mixture. Preferably, the supply of water to the reaction pot is done tangentially or along the walls of the reaction pot so as to ensure water trickles to the metal phosphide to avoid splashing of metal phopshide on the wall of reaction pot (12) which could lead to ignition. However, when water is added directly to the metal phosphide, phosphine generation starts immediately and this may lead to autoignition of phosphine gas.
In a preferred embodiment, 1 kg. phosphine gas is generated using 2.2 kg of 77.5% aluminum phosphide mixed with 10 liters of water. A supply of agitation air from an agitation air compressor 18 is fed to the reaction pot 12 via an agitation air input 20. The agitation air is fed to the reaction pot preferably tangentially to ensure that all the metal phosphide granules in the reaction mixture are stirred thoroughly and the phosphine gas generated does not lead to an ignition / explosion. The reaction mixture containing the metal phosphide and water react to generate a phosphine gas upon agitation with the agitation air. Preferably, the agitation air fed to the reaction pot 12 is ambient air. The present invention obviates the need of using inert gas for generating phosphine gas


without any fire, ignition or explosion which is a normal cause of concern when metal
phosphide is reacted with water and agitated with ambient air.
The agitation air from the agitation air compressor 18 is preferably supplied at a
turbulating pressure of 0.5 to 2 kg/cm.sup.2. The agitation air is supplied at a flow rate
such that the reaction temperature does not rise above 60 degree. C.
According to the present invention, phosphine gas has been generated up to 25,000 grams
in two hours. Higher quantities of phosphine gas can be generated within two hours as
per requirement by increasing the size of the apparatus.
Of the total quantity of phosphine gas to be generated, 40% to 50% or higher is generated in first 30 minutes of reaction.
Figures 2 to 5 show the rate of generation of phosphine. As can be seen from Figure 2, while generating 56 grams of phosphine, 34.6 grams of phosphine is generated in first 30 minutes of the reaction; i.e it is more than 50% of the total phosphine to be generated.
Similarly, figures 3 to 5 show generation of phosphine gas of 7,500 g, 10,000g and 25,000g of phosphine. The graphs show that more than 50 % of the total phosphine to be generated is generated in first 30 minutes.
The phosphine gas is then diluted by a supply of dilution air from a dilution blower 22 producing a fumigant phosphine gas. The dilution blower 22 is connected to the reaction pot 12 via a dilution air input 23. Preferably, the dilution air is supplied to the reaction pot tangentially to ensure that all the phosphine gas generated from the reaction mixture that is displaced to the surface of water is picked up by the dilution air entering the pot tangentially.
The dilution air supplied to the reaction pot is ambient air. However, air from the structure or commodity may be recycled to the reaction pot till the generation is complete to minimize loss of phosphine from the structure or commodity.


The phosphine gas in preferably diluted such that the concentration of the fumigant phosphine gas is maintained as per fumigation requirement. The amount of dilution air added to the reaction pot is such that the concentration of phosphine gas in the pot does not exceed auto ignition limit (1.79%) at STP. The dilution air is supplied at a flow rate such that the concentration of phosphine gas in the pot does not exceed auto ignition limit (1.79%) at STP.
The fumigant phosphine gas is then directly delivered to a commodity 24 to be fumigated via fumigant line 26. The term "directly delivered" should be construed to mean that the fumigant phosphine gas is fed directly to the commodity without the need for intermediate storage containers or additional dilution means, such as inert gases. The commodity 24 is preferably disposed within a storage structure, such as a silo, transport container or ship. In a preferred embodiment, any fumigant phosphine gas that does not react with the commodity exits the commodity as unreacted fumigant phosphine gas. The unreacted fumigant phosphine gas may be recycled to the commodity 24 by directing a portion of the unreacted fumigant phosphine gas to the dilution blower 22. Alternatively, any unreacted fumigant phosphine gas may be cleaned as discussed below.
Once the commodity 24 has been fumigated, any unused reaction mixture and phosphine gas may be directed to a secondary reactor 30 for deactivation. Any unused reaction mixture and phosphine gas remaining in the reaction pot 12 are preferably discharged from the reaction pot 12 via an unused reaction mixture line 28 to the secondary reactor 30 at an unused reaction mixture inlet 29. The secondary reactor 30 contains an air sparger 31 which is connected to a residue compressor 32 via a sparger inlet 33. The secondary reactor 30 is also connected to a unreacted gas blower 34 which provides air and unreacted fumigant phosphine gas to the secondary reactor 30 via an unreacted gas inlet 35. Additionally, a supply of cleaning water is supplied to the secondary reactor 30. The cleaning water may be used to scrub the unused reaction mixture and unreacted fumigant phosphine gas. The secondary reactor 30 produces a drainable residue that is free from any active metal phosphide. The drainable residue from the secondary reactor 30 is removed via residue outlet 36. The phosphine gas remaining in the secondary reactor 30 is fed to an absorption tank 38 via phosphine gas absorption line 40. Likewise,


any unreacted fumigant phosphine gas may be cleaned by directing the unreacted fumigant phosphine gas from the commodity 24 to the residual collection tank 30 via the unreacted gas blower 34 and unreacted gas inlet 35. The secondary reactor 30 and absorption tank 38 provide any environmentally friendly means by which to clean the unused reaction mixture and phosphine gas after the commodity is fumigated. In a preferred embodiment, the deactivation process takes about 180 minutes. It should be understood that one of ordinary skill in the art may utilize other similar means for removing and/or cleaning the unused reaction mixture and phosphine gas from the generator 10.
Additionally, forced air circulation devices are preferably used to evenly distribute the fumigant phosphine gas throughout the commodity 24. This greatly reduces the possibility of any localized increase in concentrate of phosphine gas which may lead to ignition or fire.
The generator 10 produces phosphine gas having the desired concentration in a short interval time, preferably less than two hours. This generation produces a maximum amount of phosphine gas and the reaction time of the phosphine gas with the commodity is very slow. The amount of phosphine gas released to the environment is negligible, preferably between 5-10 ppm. Phosphine gas can be generated in amount of from 56 gms to 25.0 Kg or higher. One treatment of a grain silo is sufficient to completely kill the insects in the commodity. Also, the preferred generator has a battery back up and hence continues safe operation in the event of power failure. The phosphine generator may be a stationary or a mobile unit as per requirement.
The details of the invention, its objects and advantages are explained hereunder in greater detail in relation to the following non-limiting exemplary illustrations.
EXAMPLE
Example -1


Phosphine generation - 56 gms
The phosphine generator is connected to a transport container (20') to be fumigated having a volume of 33.4 cub meters. One ventilator of the container is connected to the fan suction in the generator. Delivery of the fan is connected to the other ventilator on the container from the reaction pot outlet. The phosphine generated is displaced and circulated into the container. The pipe connection are made as shown in FIG 1.
125 gms of Aluminium Phosphide formulation, containing 77.7 % of the active ingredient is used for phosphine gas generation for fumigation. The formulation is in the form of granules. No dust was observed while dispensing the product into reaction pot.
Water (650 ml) is added to the pot from water tank. The generation of phosphine starts after water is added. A compressor is used to agitate the reaction mixture, to generate phosphine gas and dilute the gas generated with a fan. The gas is dispersed into the container. Gas concentration is measured at different locations in the container. There is uniformity in the gas concentration measured at different sampling points.
Experiment

Time in (min) Reaction temp (Deg.C) Cumulative PH3 generation in gms
0 32.2 0
13 43.8 16.38
30 36.9 39.62
45 30.6 45.27
60 28.2 48.40
75 27.2 50.65
93 26.8 52.66
120 26.7 55.16


The slurry from the pot was analysed for Active ingredient after 120 minutes and A.I content was found to be 0.96%.

Size of Generator Dilution air Compressed Air for Agitation
Flow rate in m3/hr Flow rate in LPM
56 gm 47 10
The residue from the pot was taken into a deactivation tank which is part of the generator. Phosphine gas which is being generated during this deactivation process is passed through a scrubber which contains a charcoal. No phosphine is released from the deactivation unit or scrubber; only clean air is let off into atmosphere from the scrubber. The active ingredient was analysed in the residue from the deactivation tank and was found to be 0.08 %. Rate of generation of phosphine gas is shown in FIG 2.
Example 2
Phosphine Generation - 7.5 kgs
The Phosphine generator is connected as shown in the FIG 1.
16.5 kgs of Aluminium Phosphide formulation, containing 77.8 % of the active ingredient was used for phosphine gas generation for fumigation. The formulation is in the form of granules. No dust was observed while dispensing the product into the reaction pot.
Water (65 Litre) is added to the pot from water tank. The generation of phosphine starts after water is added. A compressor is used to agitate the reaction mixture, to generate phosphine gas and dilute the gas generated with a fan. The gas is dispersed into the air.


Phosphine concentration was measured with PH3 monitors and temperature was also measured as shown in the Table 1 below.
Experiment

Time in (min) Reaction temp (Deg.C) Cumulative PH3 generation in kgs
0 28 0.00
15 29 0.87
31 44 3.58
43 44 5.80
82 25 7.05
92 23 7.15
122 22 7.39
The slurry from the pot was analysed for active ingredient after 120 minutes and A.I content was found to be 0.94 %.

Size of Generator Dilution air Compressed Air for Agitation
Flow rate in m3/hr Flow rate in LPM
7.5 kgs 1970 700
The residue from the pot was taken into a deactivation tank which is part of the generator.
Phosphine gas which is being generated during this deactivation process is passed
through a scrubber which contains a charcoal. No phosphine is released from the
deactivation unit or scrubber; only clean air is let off into atmosphere from the scrubber.
The active ingredient was analysed in the residue from the deactivation tank and was
0.05%.
Rate of generation of phosphine gas is shown in FIG 3.
Example 3


Phosphine generation - 10 kgs
The Phosphine generator is connected as shown in the FIG 1.
22.0 kgs of Aluminium Phosphide formulation, containing 77.8 % of the active ingredient was used for phosphine gas generation for fumigation. The formulation is in the form of granules. No dust was observed while dispensing the product into the reaction pot.
Water (87 Litre) is added to the pot from water tank. The generation of phosphine starts after water is added. A compressor is used to agitate the reaction mixture, to generate phosphine gas and dilute the gas generated with a fan. The gas is dispersed into the air.
Phosphine concentration was measured with PH3 monitors and temperature was also measured as shown in the Table 1 below.
Experiment

Time in (min) Reaction temp (Deg.C) Cumulative PH3 generation in kgs
0 33 0
16 50 3.40
35 44 8.33
50 34 8.99
65 31 9.30
80 29 9.50
95 29 9.66
120 29 9.85
The slurry from the pot was analyzed for active ingredient after 120 minutes and AI content was found to be 0.89%.


Size of Generator Dilution air Compressed Air for Agitation
Flow rate in m3/hr Flow rate in LPM
10 kgs 2606 1050
The residue from the pot was taken into a deactivation tank which is part of the generator. Phosphine gas which is being generated during this deactivation process is passed through a scrubber which contains a charcoal. No phosphine is released from the deactivation unit or scrubber; only clean air is let off into atmosphere from the scrubber. The active ingredient was analyzed in the residue from the deactivation tank and was found to be 0.08 %. Rate of generation of phosphine gas is shown in FIG 4.
Example 4
Phosphine generation - 25 kgs
The Phosphine generator is connected as shown in the FIG 1 A.
55.0 kgs of Aluminium Phosphide formulation, containing 77.8 % of the active ingredient was used for phosphine gas generation for fumigation. The formulation is in the form of granules. No dust was observed while dispensing the product into the reaction pot.
Water (216 Litre) is added to the pot from water tank. The generation of phosphine starts after water is added. A compressor is used to agitate the reaction mixture, to generate phosphine gas and dilute the gas generated with a fan. The gas is dispersed into the air.
Phosphine concentration was measured with PH3 monitors and temperature was also measured as shown in the Table 1 below.


Experiment

Time in (min) Reaction temp (Deg.C) Cumulative PH3 generation in kgs
0 21 0
15 27 2.52
30 49.6 15.10
47 36 21.47
62 26 22.78
82 23 23.73
102 21 24.32
122 20 24.78
The slurry form the pot was analysed for active ingredient after 120 minutes and A.I content was found to be 0.91%.

Size of Generator Dilution air Compressed Air for Agitation
Flow rate in m3/hr Flow rate in LPM
25 kgs 6515 2400
The residue from the pot was taken into a deactivation tank which is part of the generator. Phosphine gas which is being generated during this deactivation process is passed through a scrubber which contains a charcoal. No phosphine is released from the deactivation unit or scrubber; only clean air is let off into atmosphere from the scrubber. The active ingredient was analyzed in the residue from the deactivation tank and was found to be 0.09 %. Rate of generation of phosphine gas is shown in FIG 5.


Comparative Example
55.0 kgs of Aluminium Phosphide formulation in the form of granules containing 77.8 % of the active ingredient was used for phosphine gas generation using apparatus of the present invention as given in example 4 and comparison was done with the apparatus of IN 196518.
Experiment
Using the apparatus of IN196518, the formulation was added continuously to the reactor. Initially 2800 gms of Aluminium Phosphide containing 56.5% active ingredient was taken, was added to the reactor referred in the patent. The material is conveyed by mechanical means and simultaneously water is sprayed. The feeding was continued for 10 days and gas is generated for 10 days continuously at an almost constant rate. The rate of addition of Aluminium Phosphide was 500 gms per hour where as the average rate of release of Phosphine gas was 170 gms per hour as given in FIG 6. Heating and cooling jackets are required and soapy water is used to treat the slurry.
The table below indicates rapid release of phosphine gas using the apparatus of the present invention in comparison with the apparatus of IN 196518.

New Improved apparatus of the present invention Apparatus of parent application/ IN196518
Time in (min) Cumulative PH3 generation in kgs Time in (days) Cumulative PH3 generation in kgs
0 0 1 4.08
15 2.52 2 8.16
30 15.10 3 12.24
62 22.78 4 16.32
102 24.32 5 20.40
122 24.7 6 days 3 hrs 24.99


As seen from the table above, to generate 25000 gms of phosphine at the 170 gm / hr, 6 days and 3 hrs are required by the apparatus of IN 196518, whereas the apparatus of the present invention can generate 25000 gms of phosphine gas in about two hours. When the apparatus of IN 196518 was used without inert gas, the concentration of Phosphine gas generated was > 18,000 and explosion could occur at the end of 1 hr. The apparatus of the present invention generated phosphine gas <5000 ppm in all the trials, there was no explosion or fire hazards, hence there was no need for the use of any inert gas.


We Claim:
1. An improvement in and relating to an apparatus claimed in Patent No.
IN 196518, the improved apparatus comprising,
a) a reaction pot with a supply of water to said reaction pot;
b) providing a predetermined quantity of a metal phosphide to said reaction pot;
c) providing a supply of agitation air to said reaction pot forming a reaction mixture;
d) agitating the said reaction mixture with a supply of air tangentially at a turbulating pressure of 0.5 to 2 kg/cm2;
e) generating a predetermined quantity of phosphine gas upto 25,000 g in less than two hours where the reaction temperature not exceeding 60 degree C and
f) generating at least 50% of predetermined quantity of phosphine gas in 30 minutes;
g) diluting said phosphine gas with said supply of dilution air tangentially to the reaction pot thereby generating fumigant phosphine gas .

2. The improved apparatus as claimed in claim 1 wherein the predetermined quantity of metal phosphide used is Aluminium phosphide.
3. The improved apparatus as claimed in claim 2 wherein the Aluminium phosphide includes granular Aluminium phosphide.
4. The improved apparatus as claimed in claim 3 wherein the granular Aluminium phosphide includes upto 80 % Aluminium phosphide as the active ingredient.
5. The improved apparatus as claimed in claim 1 comprising providing a predetermined quantity of water into the reaction pot.


6. The improved apparatus as claimed in claim 1 wherein said step of providing a supply of dilution air includes providing a supply of ambient air.
7. The improved apparatus as claimed in claim 1 wherein said step of providing a supply of dilution air includes providing a supply of ambient air without using inert gas.
8. The improved apparatus as claimed in claim 5 comprising agitating the reaction mixture by a supply of air tangentially at a turbulating pressure.
9. The improved apparatus as claimed in claim 6 comprising agitating the reaction mixture by a supply of air tangentially at a turbulating pressure of 0.5 to 2 kg/cm2.
10. The improved apparatus as claimed in claim 1 comprising the step of diluting said phosphine gas with said supply of dilution air to produce a fumigant phosphine gas includes producing a fumigant phosphine gas containing 100 to 5000 ppm phosphine gas.
11. The improved apparatus as claimed in claim 1 comprising the step of directly delivering said fumigant gas to said commodity including directly delivering said fumigant gas to a silo, a transport container, or a ship containing said commodity.
12. The improved apparatus as claimed in claim 1 further comprising recycling a fumigant phosphine gas from said commodity with the supply of dilution air to the said reaction pot.
13. The improved apparatus as claimed in claim 1 further comprising a step of deactivating unused reaction mixture from the reaction pot.


14. A method for generating a fumigant phosphine gas comprising:
a) a reaction pot with a supply of water to said reaction pot;
b) providing a predetermined quantity of a metal phosphide to said reaction pot;
c) providing a supply of agitation air to said reaction pot forming a reaction mixture;
d) agitating the said reaction mixture with a supply of air tangentially at a turbulating pressure of 0.5 to 2 kg/cm2;
e) generating a predetermined quantity of phosphine gas upto 25,000g in less than two hours where the reaction temperature not exceeding 60 degree C and
f) generating at least 50% of predetermined quantity of phosphine gas in 30 minutes;
g) diluting said phosphine gas with said supply of dilution air tangentially to the reaction pot thereby generating fumigant phosphine gas .
15. A process for rapid generation of fumigant phosphine gas comprising
a) a reaction pot with a supply of water to said reaction pot;
b) providing a predetermined quantity of a metal phosphide to said reaction pot;
c) providing a supply of agitation air to said reaction pot forming a reaction mixture;
d) agitating the said reaction mixture with a supply of air tangentially at a turbulating pressure of 0.5 to 2 kg/cm2;
e) generating a predetermined quantity of phosphine gas upto 25,000 g in less than two hours where the reaction temperature not exceeding 60 degree C and
f) generating at least 50% of predetermined quantity of phosphine gas in 30 minutes;
g) diluting said phosphine gas with said supply of dilution air tangentially to the reaction pot thereby generating fumigant phosphine gas.


16. An improvement in and relating to an apparatus as claimed in Patent No. IN 196518 as herein described with reference to the preferred aspects, embodiments and features of the invention and illustrated with reference to the examples.
17. An improvement in and relating to a method for generating a fumigant phosphine gas as claimed in Patent No. IN196518 as herein described with reference to the preferred aspects, embodiments and features of the invention and illustrated with reference to the examples.




Abstract:
Disclosed is an improved apparatus for rapid and continuous generation of phosphine fumigant gas. The improvement comprises production of phosphine gas in a rapid manner to attain the desired concentration of phosphine gas in a very short period of time. Also described is a method for the generation of the phosphine gas allowing the rapid production of phosphine gas for on-site generation.