A system and method for safe generation of phosphine gas

Abstract

The present invention relates to a system (10) and for safe generation of phosphine gas. The present invention also relates to a process for generating phosphine gas in the presence of CO2 for limited period. The system includes a reaction pot (12) configured to receive metal phosphide (14) and water as an input. The metal phosphide (14) and water react to generate phosphine gas. Further, the system includes an air compressor (18) fluidly coupled to the reaction pot. The air compressor is configured to supply pressurized air to the reaction pot to agitate the mixture of metal phosphide (14) and water. Furthermore, the system includes a carbon dioxide supply unit (40) fluidly coupled to the reaction pot and configured to supply carbon dioxide gas to the reaction pot to maintain phosphine gas concentration below 5000 ppm to prevent fire hazard.

Description

[0001] TITLE: A SYSTEM AND METHOD FOR SAFE GENERATION OF PHOSPHINE GAS

[0002] TECHNICAL FIELD

[0003] Present disclosure, in general, relates to the field of chemical engineering. Particularly, but not exclusively, the present disclosure relates to a system and method for safe generation of phosphine gas.

[0004] BACKGROUND

[0005] Fumigation of stored agricultural commodities such as grains with phosphine gas is a preferred method for preventing insect damage. Typically, fumigation is achieved by introducing pellets or tablets containing metal phosphide directly into the grain to be fumigated. The metal phosphide reacts with the ambient moisture in the air and grain, resulting in the generation of a phosphine gas and other inert gases. Forced air circulation devices are often used to assist in the distribution of the phosphine gas throughout a storage structure, such as a grain silo.

[0006] One of the more effective ways of insect control is to generally maintain a predefined concentration of phosphine for known period of time. Methods and systems have been used to generate large quantities of phosphine gas using a phosphine generator. However, it is very difficult to achieve uniform desired phosphine concentration during fumigation. It is to be noted that phosphine gas is highly flammable and systems that increase production of phosphine increase risk of fire hazards and thermal accidents. Such hazardous environments may lead to explosions or even death of operating personnel. Occasionally due to change in reactivity of metal phosphide granules, the concentration of phosphine gas goes above 5000 ppm and the reaction temperature above 55 °C. Such conditions lead to unsafe operating environment during generation of phosphine gas.

[0007] The present disclosure is directed to overcome one or more limitations stated above. The background section of the present disclosure should not be considered as a limitation of the present disclosure.

[0008] The drawbacks / difficulties / disadvantages / limitations of the conventional techniques explained in the background section are just for exemplary purpose and the disclosure would never limit its scope only such limitations. A person skilled in the art would understand that this disclosure and below mentioned description may also solve other problems or overcome the other drawbacks / disadvantages of the conventional arts which are not explicitly captured above. SUMMARY OF THE DISCLOSURE

[0009] One or more shortcomings of the conventional design are overcome by configuration of a seat assembly as claimed and additional advantages are provided through the provision of such seat assembly as claimed in the present disclosure.

[0010] Additional features and advantages are realized through the design of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

[0011] In one non-limiting embodiment of the disclosure, a system for safe generation of phosphine gas is disclosed. The system includes a reaction pot configured to receive metal phosphide and water as an input. The metal phosphide and water react to generate phosphine gas. The system includes a water reservoir fluidly coupled to the reaction pot and configured to store water to be supplied to the reaction pot. Further, the system includes an air compressor fluidly coupled to the reaction pot. The air compressor is configured to supply pressurized air to the reaction pot to agitate the mixture of metal phosphide and water. Furthermore, the system includes a carbon dioxide supply unit fluidly coupled to the reaction pot and configured to supply carbon dioxide gas to the reaction pot at a rate ranging between 0.15 - 45 kg / hr for generation of 50 g to 15000 g of PH3 per cycle, preferably 0.15 - 30 kg / hr for generation of 50 g to 10000 g of PH3 per cycle for a time ranging between 6 minutes to 26 minutes, preferably 9 minutes to 18 minutes such that ratio of phosphine to carbon dioxide is PH3 >50 & CO2 < 50. The carbon dioxide gas may be supplied to maintain a phosphine gas concentration below 5000 ppm The system includes an air blowing unit fluidly coupled to the reaction pot. The air blowing unit is configured to blow out phosphine gas via an outlet port i£-a phosphine gas concentration 5000ppm. Additionally, the system includes a fumigant line fluidly coupled to the reaction pot and configured to supply phosphine gas from the reaction pot which includes carbon dioxide and air to a commodity to be fumigated.

[0012] In an embodiment of the disclosure, the metal phosphide is Aluminum phosphide 77.5%, supplied in a granular form.

[0013] In an embodiment of the disclosure, the ratio of metal phosphide to water supplied to the reaction pot is 1 : 11. In an embodiment of the disclosure, produces 50g - 50 kg of phosphine gas in under 2 hours of operation of the system.

[0014] In an embodiment of the disclosure, produces 50g - 40 kg of phosphine gas in under 2 hours of operation of the system.

[0015] In a preferred embodiment of the disclosure, produces 50g - 30 kg of phosphine gas in under 2 hours of operation of the system.

[0016] In another preferred embodiment of the disclosure, produces 50g - 20 kg of phosphine gas in under 2 hours of operation of the system.

[0017] In more preferred embodiment of the disclosure, produces 50g - 15 kg of phosphine gas in under 2 hours of operation of the system.

[0018] In more preferred embodiment of the disclosure, produces 50g - 10 kg of phosphine gas in under 2 hours of operation of the system.

[0019] In an embodiment the metal phosphide is kept in a suspended form.

[0020] In an embodiment of the disclosure, the reaction pot includes at least one gas sensor for detection and determination of quantity of phosphine gas and carbon dioxide case in the reaction pot and at least one temperature sensor for determination of temperature of reaction.

[0021] In an embodiment of the disclosure, the carbon dioxide supply unit includes a carbon dioxide source for supplying pressurized carbon dioxide to the reaction pot. Further, the carbon dioxide supply unit includes a regulator fluidly coupled to the reaction pot and the carbon dioxide source. The regulator is configured to selectively allow flow of the carbon dioxide to the reaction pot.

[0022] In an embodiment, the carbon dioxide is supplied to the reaction pot for 5-15 mins, preferable for 8-15 mins, preferably for 9-15 mins, preferably for 10-15 mins, more preferably for 9-14 mins.

[0023] In an embodiment of the disclosure, the system includes a deactivation unit fluidly coupled to the reaction pot via a drain valve. The deactivation unit is configured to deactivate unused reaction mixture from the reaction pot.

[0024] In one non-limiting embodiment of the disclosure, a method for safe generation of phosphine gas is disclosed. The method includes receiving metal phosphide and water as an input by a reaction pot. Further, the method includes supplying pressurized air to the reaction pot by an air compressor to agitate a reaction mixture of metal phosphide and water followed by supplying carbon dioxide gas to the reaction pot by a carbon dioxide supply unit at a rate ranging between 0.15 - 45 kg / hr for generation of 50 g to 15000 g of PH3 per cycle, preferably 0.15 - 30 kg / hr for generation of 50 g to 10000 g of PH3 per cycle for a time ranging between 6 minutes to 26 minutes, preferably 9 minutes to 18 minutes such that ratio of phosphine gas to carbon dioxide is PH3 >50 & CO2 < 50. Furthermore, the method includes blowing out phosphine gas via an outlet port of the reaction pot by an air blowing unit. Additionally, the system includes supplying phosphine gas to a commodity by a fumigant line fluidly coupled to the reaction pot.

[0025] In an embodiment of the disclosure, the method for safe generation of phosphine gas includes detecting and determining by a gas sensor quantity of phosphine gas.

[0026] In an embodiment of the disclosure, the method for safe generation of phosphine gas includes supplying pressurized carbon dioxide to the reaction pot by a carbon dioxide source. Further, the method includes selectively allowing flow of carbon dioxide to the reaction pot by a regulator. The regulator is fluidly coupled to the reaction pot and the carbon dioxide source.

[0027] In an embodiment of the disclosure, the method for safe generation of phosphine gas includes deactivating unreacted mixture of metal phosphide and water in the reaction pot by a deactivation unit fluidly coupled to the reaction pot via a drain valve.

[0028] It is to be understood that the aspects and embodiments of the disclosure described above may be used in combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

[0029] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

[0030] The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

[0031] Fig- 1 is a schematic view illustrating a system for safe generation of phosphine gas, in accordance with an embodiment of the disclosure.

[0032] Fig- 2 is a flow chart of a method for safe generation of phosphine gas, in accordance with an embodiment of the disclosure.

[0033] Fig. 3a is a graphical representation of concentration of phosphine vs time period for release of 56 gm of phosphine in a reaction pot at normal rate of reaction, in accordance with an embodiment of the disclosure.

[0034] Fig. 3b is a graphical representation of temperature of reaction vs time period during release of 56 gm of phosphine at normal reaction temperature, in accordance with an embodiment of the disclosure.

[0035] Fig. 3c is a graphical representation of concentration of phosphine vs time period for release of 56 gm of phosphine in a reaction pot at high rate of reaction, in accordance with an embodiment of the disclosure.

[0036] Fig. 3d is a graphical representation of temperature of reaction vs time period during release of 56 gm of phosphine at high reaction temperature, in accordance with an embodiment of the disclosure.

[0037] Fig. 3e is a graphical representation of concentration of phosphine vs time period for release of 56 gm of phosphine with a fixed rate of injection of carbon dioxide, in accordance with an embodiment of the disclosure. Fig. 3f is a graphical representation of temperature of reaction vs time period during release of 56 gm of phosphine during the injection of carbon dioxide, in accordance with an embodiment of the disclosure.

[0038] Fig. 4a is a graphical representation of concentration of phosphine vs time period for release of 250 gm of phosphine in a reaction pot at normal rate of reaction, in accordance with an embodiment of the disclosure.

[0039] Fig. 4b is a graphical representation of temperature of reaction vs time period during release of 250 gm of phosphine at normal reaction temperature, in accordance with an embodiment of the disclosure.

[0040] Fig. 4c is a graphical representation of concentration of phosphine vs time period for release of 250 gm of phosphine in a reaction pot at high rate of reaction, in accordance with an embodiment of the disclosure.

[0041] Fig. 4d is a graphical representation of temperature of reaction vs time period during release of 250 gm of phosphine at high reaction temperature, in accordance with an embodiment of the disclosure.

[0042] Fig. 4e is a graphical representation of concentration of phosphine vs time period for release of 250 gm of phosphine with a fixed rate of injection of carbon dioxide, in accordance with an embodiment of the disclosure.

[0043] Fig. 4f is a graphical representation of temperature of reaction vs time period during release of 250 gm of phosphine during the injection of carbon dioxide, in accordance with an embodiment of the disclosure.

[0044] Fig. 5a is a graphical representation of concentration of phosphine vs time period for release of 1000 gm of phosphine in a reaction pot at normal rate of reaction, in accordance with an embodiment of the disclosure.

[0045] Fig. 5b is a graphical representation of temperature of reaction vs time period during release of 1000 gm of phosphine at normal reaction temperature, in accordance with an embodiment of the disclosure. Fig. 5c is a graphical representation of concentration of phosphine vs time period for release of 1000 gm of phosphine in a reaction pot at high rate of reaction, in accordance with an embodiment of the disclosure.

[0046] Fig. 5d is a graphical representation of temperature of reaction vs time period during release of 1000 gm of phosphine at high reaction temperature, in accordance with an embodiment of the disclosure.

[0047] Fig. 5e is a graphical representation of concentration of phosphine vs time period for release of 1000 gm of phosphine with a fixed rate of injection of carbon dioxide, in accordance with an embodiment of the disclosure.

[0048] Fig. 5f is a graphical representation of temperature of reaction vs time period during release of 1000 gm of phosphine during the injection of carbon dioxide, in accordance with an embodiment of the disclosure.

[0049] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

[0050] DETAILED DESCRIPTION

[0051] The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent processes do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

[0052] The terms “comprises”, “comprising”, or any other variations thereof used in the specification, are intended to cover a non-exclusive inclusion, such that the system comprises a list of features / elements or steps does not include only those features / elements, but may include other features and elements not expressly listed or inherent to such setup or structure. In other words, one or more features / elements in a system proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system thereof. Also, the terms like “at least one” and “one or more” may be used interchangeably or in combination throughout the description.

[0053] Embodiments of the present disclosure discloses a system and method for safely generating phosphine gas. The system includes a reaction pot for receiving a mixture of metal phosphide and water and allow a hydrolysis reaction between metal phosphide and water. Further, the system includes an air compressor fluidly coupled to the reaction pot and configured to supply pressurized air to the reaction pot to agitate the mixture of metal phosphide and water. Furthermore, the system includes a carbon dioxide supply unit fluidly coupled to the reaction pot to supply carbon dioxide to the reaction pot. The carbon dioxide gas in the reaction pot assists in maintaining the concentration of phosphine gas under 5000 ppm and consequently reduce fire and safety risk.

[0054] Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, same numerals will be used to refer to the same or like parts. Embodiments of the disclosure are described in the following paragraphs with reference to Figs. 1 to 5f, the same element or elements which have same functions are indicated by the same reference signs.

[0055] Fig. 1 is illustrative of a system (10) for safe generation of phosphine gas. The system (10) includes a reaction pot (12) configured to receive metal phosphide (14) and water as input. The reaction pot (12) may be a container with predefined size and shape configured to accommodate predefined quantity of metal phosphide (14) and water. The reaction pot (12) may be made of inert materials for a clean and contamination free reaction environment between metal phosphide (14) and water. In an embodiment, the reaction pot (12) may be coupled to a heating element to maintain a predefined temperature of the reaction pot (12) for optimal rate of reaction between the metal phosphide (14) and water. In an embodiment, the metal phosphide (14) may be any one of aluminum phosphide or magnesium phosphide. Further, the system (10) may include a water reservoir (16) fluidly coupled to the reaction pot (12). The water reservoir (16) may be designed to store a predefined quantity of water. The water reservoir (16) may be configured to supply water to the reaction pot (12) to allow formation of mixture of metal phosphide (14) and water. The metal phosphide (14) readily reacts with water by a hydrolysis reaction to release phosphine gas. The water reservoir (16) may be coupled to the reaction pot (12) by means of nozzles mounted tangentially to the reaction pot (12) to prevent splashing of water within the reaction pot (12). Additionally, the system (10) includes an air compressor (18) fluidly coupled to the reaction pot (12) and configured to supply pressurized air to the reaction pot (12) to agitate the mixture of metal phosphide (14) and water. Use of the air compressor (18) is preferred over rotating parts such as agitators, stirrers and rotors to reduce metal -to-metal contact friction thereby reducing wear and tear of the reaction pot (12).

[0056] Rate of generation of phosphine gas is related to rate of reaction between metal phosphide (14) and water. Accordingly, rate of production of phosphene is dependent on quantity of metal phosphide (14) and quantity of carbon dioxide supplied to the reaction pot (12). However, additional process parameters such as temperature, pressure of the reaction pot (12) may also contribute to rate of reaction between metal phosphide (14) and water. Carbon dioxide supply unit may be configured to supply carbon dioxide gas to the reaction pot at a rate ranging between 0.15 - 45 kg / hr for generation of 50 g to 15000 g of phosphine per cycle for a time ranging between 6 minutes to 26 minutes. In an embodiment, the carbon dioxide supply unit may be configured to supply carbon dioxide gas to the reaction pot at a rate ranging between 0.15 - 30 kg / hr for generation of 50 g to 10000 g of PH3 per cycle for a time ranging between 9 minutes to 18 minutes. Use of the air compressor (18) assists in increasing rate of reaction between metal phosphide (14) and water.

[0057] As shown in Fig. 1, the system (10) includes a carbon dioxide supply unit (40) fluidly coupled to the reaction pot (12) and configured to supply carbon dioxide gas to the reaction pot (12) at a pre-defined rate for a predetermined time period. Further, carbon dioxide gas may be supplied to the reaction pot (12) to maintain the concentration of phosphine gas below 5000 ppm. Furthermore, the carbon dioxide supply unit (40) may include a carbon dioxide source (42) for supplying pressurized carbon dioxide to the reaction pot (12). In an embodiment, the carbon dioxide source (42) may be a pressurized carbon dioxide generating (56) device. Additionally, the carbon dioxide supply unit (40) may include a regulator (44) fluidly coupled to the reaction pot (12) and the carbon dioxide source (42). The regulator (44) may be configured to selectively allow flow of carbon dioxide to the reaction pot (12). Addition of carbon dioxide to the reaction pot (12) reduces the concentration of phosphine in the reaction pot (12). Such reduced concentration of phosphine in the reaction pot (12) reduces chances of fire hazards and combustion. In an embodiment, the system (10) may include at least one gas sensor (48) to detect concentration of phosphine gas and concentration of carbon dioxide in the reaction and a temperature sensor (49) to measure the temperature of the reaction. The system (10) may also include a control unit (50) communicatively coupled to the at least one gas sensor (48). The control unit (50) may be configured to receive data corresponding to concentration of phosphine gas in the reaction pot (12). Such data from the at least one gas sensor (48) may be used to regulate the flow of carbon dioxide to the reaction pot (12) by operating the regulator (44) to maintain concentration of phosphine gas below 5000ppm.

[0058] Referring again to Fig. 1, the system (10) includes an air blowing unit (22) fluidly coupled to the reaction pot (12) to provide dilution air to the reaction pot (12) to maintain phosphine gas concentration below 5000 ppm in the reaction pot (12). During operation of the system (10), due to rapid increase in rate of reaction between the metal phosphide (14) and water, large quantity of phosphine may be generated. Such large quantity of phosphine may result in the gas being dense and consequently, accumulation of phosphine takes place thereby increasing risk of fire hazard and combustion of phosphine. The air blowing unit (22) may be used to blow out phosphine gas released due to rapid generation of phosphine gas. Furthermore, the diluted phosphine gas in the reaction pot (12) may be supplied to a commodity (24) often placed at a certain distance from the system (10). The term commodity (24) may refer to any storage unit such as but not limited to silos, transport containers or ships etc. capable of storing grains and other materials to be fumigated. The diluted phosphine gas may be supplied to the commodity (24) by a fumigant line fluidly coupled to the reaction pot (12). The phosphine gas generated and diluted in the reaction pot (12) may be supplied to the commodity (24) directly without need for additional dilution means or storage units. In an embodiment, the phosphine gas may be expunged from the commodity (24) post fumigation without any reaction with the stored products in the commodity (24). Unreacted metal phosphide (14) and water may be directed to a deactivation unit (46) fluidly coupled to the reaction pot (12) via a drain valve (28). In an embodiment, the drain valve (28) may be positioned below the reaction pot (12) to direct unreacted mixture of the metal phosphide (14) and water. The deactivation unit (46) may be configured to deactivate unused reaction mixture in the reaction pot (12). The deactivation unit (46) may include a secondary reactor (30) fluidly coupled to the drain valve (28) and configured to receive the unreacted mixture of metal phosphide (14) and water. Further the deactivation unit (46) may include a sparger (31) coupled to a residue compressor (32). A sparger (31) may be configured to supply the unreacted metal phosphide (14) from the reaction pot (12) to the secondary reactor (30) by mechanical assistance of the residue compressor (32). Furthermore, the deactivation unit (46) may include a unreacted gas blower (34) fluidly coupled to the secondary reactor (30) to provide air to the unreacted metal phosphide (14). Additionally, the deactivation unit (46) may be supplied with water, particularly to the secondary reactor (30) to deactivate the unreacted metal phosphide (14). The aforementioned mixture of water and unreacted metal phosphide (14) in reaction pot (12) may form a drainable residue within the secondary reactor (30). Such drainable residue may be removed via a residue outlet (36) positioned below the secondary rector. However, the position of the residue outlet (36) should not be considered as a limitation rather an example of positioning of said residue outlet (36). Remaining metal phosphide (14) and water in the secondary rector may be fed to an absorption tank (38) via an absorption line. The secondary reactor (30) and the absorption / adsorption tank (38) may provide any environmentally friendly means by which to clean the unreacted mixture of metal phosphide (14) and water.

[0059] Referring now to Fig. 2 which is an exemplary embodiment of the present disclosure illustrating a flow chart of a method (200) for safe generation of phosphine gas. In an embodiment, the method (200) may be implemented in a system (10) used for producing phosphine gas.

[0060] The order in which the method (200) is described is not intended to be construed as a limitation, and any number of the described method (200) blocks may be combined in any order to implement the method (200). Additionally, individual blocks may be deleted from the method (200) without departing from the scope of the subject matter described herein. Furthermore, the method (200) can be implemented in any suitable hardware, software, firmware, or combination thereof. At block 101, metal phosphide (14) and water may be received as inputs by the reaction pot (12). The reaction pot (12) may be a container capable of receiving predefined quantity of metal phosphide (14) and water. In an embodiment, the method (200) may use aluminum phosphide or magnesium phosphide to generate phosphine gas. The metal phosphide (14) and water react via a hydrolysis reaction to release phosphine gas

[0061] At block 102, the reaction pot (12) may be supplied with pressurized air by an air compressor (18) to increase rate of formation of the phosphine gas by agitating the mixture of metal phosphide (14) and water and keeping the metal phosphide (14) in suspension.

[0062] At block 103, the concentration of phosphine may be reduced by the air blower supplying air in a tangential manner to direct the phosphine gas to the fumigant line.

[0063] At block 104, the reaction pot (12) may be supplied with carbon dioxide gas at a predefined rate for a fixed to time to dilute concentration of phosphine gas in the reaction pot (12) below 5000 ppm to reduce risk of fire and instant combustion of phosphine gas

[0064] At block 105, the diluted concentration of phosphine gas along with carbon dioxide may be supplied to the commodity (24) by the fumigant line to fumigate the commodity (24) for preventing insect infestation of the commodity (24).

[0065] In an operational embodiment, the metal phosphide (14) may be supplied to the reaction pot (12) along with water from the water reservoir (16). The metal phosphide (14) may be aluminum phosphide 77.5% supplied in granular form. Agitation of mixture of aluminum phosphide 77.5% and water may be carried out by the air compressor (18) to generate phosphine gas. In an embodiment, the ratio of phosphides to water supplied to the reaction pot (12) may be 1 : 11. In another embodiment, the system (10) may produce 50g to 50 kg of phosphine gas in under 2 hours of operation of the system (10) subject to dimension and size of reaction pot (12), quantity of water and metal phosphide (14) being added to the reaction pot (12) and rate of reaction between metal phosphide (14) and water. Further, the at least one gas sensor (48) coupled to the reaction pot (12) may be configured to receive data corresponding to concentration of phosphine, carbon dioxide in the reaction pot (12) while the at least one temperature sensor (49) may be configured to detect temperature of the reaction in the reaction pot (12). The control unit (50) communicatively coupled to the at least one gas sensor (48) may be configured to operate the regulator (44) to allow flow of carbon dioxide from the carbon dioxide source (42) to the reaction pot (12) to maintain concentration of phosphine in the reaction pot (12) below 5000ppm. The air blowing unit (22) may be configured to blow out phosphine gas from the reaction pot (12). In an embodiment, the carbon dioxide gas may be supplied to the reaction pot (12) at a rate ranging between 0.15kg / hour to 45kg / hour for a time ranging between 9 minutes to 18 minutes such that ratio of phosphine to carbon dioxide is PH3 >50 & CO2 < 50, the carbon dioxide gas. In an embodiment, the method (200) used in present disclosure may be used to generate 50g - 50 kgs of phosphine using 22kg of metal phosphide (14) in 2hrs subject to rate of reaction between metal phosphide (14) and water. A routine practice can increase the yield of Phosphine produced up to 50 Kgs and more.

[0066] Experiments were conducted for generation of different quantities of phosphine gas. Trials were taken for generating 56 g, 250 g and 1000 g of phosphine gas from Aluminum Phosphide 77.5 % granules. The following experiments were conducted and represented in Fig. 3a-5f.

[0067] During normal rate of generation i.e., when phosphine gas concentration is below 5000 ppm of phosphine gas from Aluminum Phosphide 77.5 % granules, a peak phosphine gas concentration is reached in 14 to 18 minutes and the reaction temperature does not exceed 55 °C. Fig. 3a, Fig. 4a and Fig. 5a shows the normal rate of generation of phosphine gas and Fig. 3b, Fig. 4b and Fig. 5b shows normal reaction temperature.

[0068] During high reactivity i.e., when the phosphine gas concentration exceeds 5000 ppm, metal phosphide (14) of 77.5 % Aluminum phosphide granules, the peak phosphine gas concentration is reached in 10-16 minutes and the temperature goes above 55°C. while the peak concentration exceeds 5000 ppm. Fig 3c, 4c and 5c shows higher rate of generation of phosphine gas and Fig. 3d, 4d and 5d shows variation in temperature vs time behavior during high rate of generation of phosphine.

[0069] Trials were performed by introducing carbon dioxide gas (CO2) during reaction of metal phosphide (14) and water to reduce the phosphine gas concentration and to avoid fire / ignition. The CO2 was inj ected at the 9thminute from the start of the reaction & continued for 10 minutes. No fire or smoke observed after introduction of CO2. The phosphine concentration and temperature was below 5000 ppm & 55 °C respectively. Fig. 3e, 4e and 5e shows CO2 - phosphine concentration below 5000 ppm and Fig. 3f, 4f and 5f shows temperature vs time behavior in the reaction pot (12) during generation of phosphine and addition of CO2 . The CO2 is injected at the rate of 0.15, 0.75& 3 kg / hour for 56 g , 250 g & 1000 g respectively. The phosphine gas is preferably diluted such that the phosphine gas concentration below 5000 ppm and does not exceed a temperature of 55 °C’ The phosphine gas is then directly supplied to the storage structure for fumigation.

[0070] EQUIVALENTS

[0071] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity.

[0072] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

[0073] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0074] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

[0075] Referral numerals:

Claims

We Claim:1 . A system (10) for safe generation of phosphine gas, the system (10) comprising: a reaction pot (12) configured to receive metal phosphide (14) and water as an input, wherein the metal phosphide (14) and water react to generate (10) phosphine gas; a water reservoir (16) fluidly coupled to the reaction pot (12) and configured to store water to be supplied to the reaction pot (12); an air compressor (18) fluidly coupled to the reaction pot (12), the air compressor (18) being configured to supply pressurized air to the reaction pot (12) to agitate the mixture of metal phosphide (14) and water; a carbon dioxide supply unit (40) fluidly coupled to the reaction pot (12) and configured to supply carbon dioxide gas to the reaction pot (12) at a rate ranging between 0.15kg / hour to 30kg / hour for a time ranging between 9 minutes to 18 minutes such that ratio of phosphine to carbon dioxide is PH3 >50 & CO2 < 50, the carbon dioxide gas may be supplied to maintain a phosphine gas concentration below 5000 ppm; a fumigant line (26) fluidly coupled to the reaction pot (12) and configured to supply phosphine gas from the reaction pot (12) comprising carbon dioxide and air to a commodity (24) to be fumigated.

2. The system (10) as claimed in claim 1 comprises an air blowing unit (22) fluidly coupled to the reaction pot (12), wherein the air blowing unit (22) is configured to blow out phosphine gas via an outlet port.

3. The system (10) as claimed in claim 1, wherein the metal phosphide (14) is Aluminum phosphide 77.5%, supplied in a granular form.

4. The system (10) as claimed in claim 1, wherein the ratio of phosphine gas generated to water supplied to the reaction pot (12) is 1 : 11.

5. The system (10) as claimed in claim 1, wherein the carbon dioxide is supplied for 5-15 mins.

6. The system (10) as claimed in claim 1, wherein rate of production of phosphene is dependent on quantity of metal phosphide and quantity of carbon dioxide supplied to the reaction pot (12).

7. The system (10) as claimed in claim 1 produces 50g- 50 kg of phosphine gas in under 2 hours of operation of the system (10).

8. The system (10) as claimed in claim 7 produces 50g- 30 kg of phosphine gas in under 2 hours of operation of the system (10).

9. The system (10) as claimed in claim 1, wherein the reaction pot (12) comprises at least one gas sensor (48) for detection and determination of quantity of phosphine gas and carbon dioxide in the reaction pot, and at least one temperature sensor (49) for measuring reaction temperature.

10. The system (10) as claimed in claim 1, wherein the carbon dioxide supply unit (40) comprises: a carbon dioxide source (42) for supplying pressurized carbon dioxide to the reaction pot (12); a regulator (44) fluidly coupled to the reaction pot (12) and the carbon dioxide source (42) (44), wherein the regulator (44) is configured to selectively allow flow of the carbon dioxide to the reaction pot (12).11 . The system (10) as claimed in claim 1 comprises a deactivation unit (46) fluidly coupled to the reaction pot (12) via a drain valve (28), the deactivation unit (46) is configured to deactivate unused reaction mixture in the reaction pot (12).

12. A method (200) for safe generation of phosphine gas, method (200) comprising: receiving metal phosphide (14) and water as an input by a reaction pot (12); supplying pressurized air to the reaction pot (12) by an air compressor (18) to agitate a reaction mixture of metal phosphide (14) and water; supplying carbon dioxide gas to the reaction pot (12) by a carbon dioxide supply unit (40) at a rate ranging between 0.15kg / hour to 30kg / hour in time ranging between 9minutes to 18 minutes such that ratio of phosphine gas to carbon dioxide is PH3 >50 & CO2 < 50; blowing out phosphine gas via an outlet port of the reaction pot (12) by an air blowing unit (22) supplying phosphine gas to a commodity (24) by a fumigant line (26) fluidly coupled to the reaction pot (12).

13. The method (200) as claimed in claim 12, wherein the metal phosphide (14) is Aluminum phosphide 77.5%, supplied in a granular form.

14. The method (200) as claimed in claim 12, wherein the ratio of phosphine gas generated to water supplied to the reaction pot (12) is 1 : 11.

15. The method (200) as claimed in claim 12 produces 50g - 50kgs of phosphine gas in under 2 hours of operation of the system (10)16. The system (10) as claimed in claim 13 produces 50g- 30 kg of phosphine gas in under 2 hours of operation of the system (10)17. The method (200) as claimed in claim 12, wherein detecting and determining by a gas sensor (48) quantity of phosphine gas and carbon dioxide in the reaction pot, determining reaction temperature by temperature sensor.

18. The method (200) as claimed in claim 12, wherein the carbon dioxide supply unit (40) comprises: supplying pressurized carbon dioxide to the reaction pot (12) by a carbon dioxide source (42); selectively allowing flow of carbon dioxide to the reaction pot (12) by a regulator (44), the regulator (44) being fluidly coupled to the reaction pot (12) and the carbon dioxide source (42).

19. The method (200) as claimed in claim 12 comprises deactivating unused mixture of metal phosphide (14) and water in the reaction pot (12) by a deactivation unit (46) fluidly coupled to the reaction pot (12) via a drain valve (28).

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