Title of Invention

PORTABLE FUMIGATOR

Abstract

A portable fumigator (1) comprising a gas tight reactor (2) made of a mechanically strong corrosion resistant inert material and mounted on a frame (3) provided with wheels (4a, 4a, 4b) and a handle (5). the reactor is provided with at least one sight glass (6) at the side thereof. The top of the reactor is provided with a carbon dioxide inlet line (7) having a first flow control valve (8) and flow indicator (9), a water inlet passage (10) having a second flow control valve (11), a gas outlet (12) fitted with an impingement column (13) provided with a pressure sensor (14) and a gas outlet line (15) and a regulated metal phosphide tablet feeder (17). The bottom of the reactor is provided with a sludge outlet line (31) having a valve (32) provided therein (fig 1).

Full Text

FORM 2 THE PATENTS ACT 1970 As amended by the Patents (Amendment) Act, 2002 COMPLETE SPECIFICATION J ? TITLE (See Section 10; Rule 13) Portable fumigator APPLICANTS Excel Crop Care Limited, 184-87, Swami Vivekanand Road, Jogeshwari, Mumbai 400 102, Maharashtra, India, an Indian Company INVENTORS Shroff Dipesh Kantisen, Dhuri Arun Vishnu and Auti Avinash Shivaji, all Indian Nationals and all of Excel Crop Care Limited, 184-87, Swami Vivekanand Road, Jogeshwari, Mumbai 400 102, Maharashtra, India The following specification particularly describes the nature of this invention and the manner" in which it is to be performed : GRANTED 28-2-2005 FIELD OF INVENTION This invention relates to a portable fumigator. Phosphine gas based fumigators are widely used in pest control, especially in the fumigation of agricultural bulk commodities such as grains, legumes, peas or nuts. Phosphine gas is generated by reacting water with metal phosphides such as aluminium phosphide. PRIOR ART US Patent No 5411704 relates to a fumigating apparatus comprising a generator vessel containing a bed of metal phosphide pellets supported on a gas pervious support. Air is pumped into the bottom of the vessel by a gas pump such as diaphram pump through a moisture regulating means. The air proceeds past a moisture sensor and a bypass duct. The air is moisturized as it passes through the moisture regulating means. When the moist air travels through the bed, the water in the air causes hydrolysis of the metal phosphide to generate phosphine which flows out through a dust separator and throttle valve. The apparatus includes an inert fluid (such as carbon dioxide) supply source 2 connected to the vessel as a safety means. The movement of the apparatus is difficult as it is without wheels. Therefore, it is not easily portable to the fumigation site and it may become necessary to collect and transport phosphine to the fumigation site. This is inconvenient and expensive. Besides, it comprises a large number of components and is bulky. It also requires precise electronic controls for the pump and the moisture regulating means. It is further expensive for the above reasons. US Patent No 5573740 describes an apparatus for generating phosphine comprising a phosphine generating chamber. Pellets or tablets of metal phosphide are placed at the bottom of the chamber and moist air is blown into the chamber by a fan. Moist air permeates through permeable membrane in the chamber and reaches the metal phosphide. Water in the air on coming into contact with the metal phosphide reacts with the metal phosphide to generate phosphine which also permeates through the membrane. Phosphine generation may be controlled by a movable blanking plate disposed over the membrane. Excess phosphine generated in the chamber may be absorbed by a rod or bar made of phosphine absorbent compounds such as copper chloride and provided in the chamber . Alternatively the chamber may contain water and 3 pellets or tablets of metal phosphide are fed into the chamber from a hopper through a transfer means comprising a perforated vertically rotatable disc which is operated by a solenoid arrangement. The apparatus is provided with an electric heater associated with a thermostat to maintain a constant temperature of the water in the chamber. The water in the chamber reacts with the metal phosphide to generate phosphine. The chamber includes a stirrer and a bubbler. The apparatus may include a safety means comprising a purge gas reservoir connected to the chamber through a purge gas conduit provided with a valve activation means. The apparatus is without wheels and suffers from the drawbacks disclosed earlier. The alternative construction of the apparatus comprises a large number of components and is bulky. It is also energy intensive and further expensive. US Patent No 5897841 teaches an apparatus for the on-site production of phosphine comprising an elongated reactor supported on a mobile frame with wheels. The reactor is provided with an internal mixing means comprising an elongated axially rotatable shaft coupled to a drive assembly including an electric motor. The reactor is also provided with an elongated 4 external heating jacket and an external cooling jacket. The apparatus includes a delivery assembly for supplying a reactant gas comprising a carrier gas (carbon dioxide) and water to the reactor. Particulate metal phosphide is fed into the reactor through a delivery unit comprising a hopper and a pulveriser. The water reacts with the metal phosphide to generate phosphine. The apparatus includes an output device for delivery of phosphine and a receiver (tank equipped with agitator) for receiving waste slurry. The apparatus is also provided with an acidic medium supplying tank connected to the reactor. The apparatus is energy intensive and comprises a large number of components and is bulky and expensive. US Patent No 6315965 discloses a phosphine generator comprising a phosphine generating chamber containing water upto certain level. The space in the chamber above the water level is partitioned into two subchambers by a vertical partition extending from the top of the chamber down to the water surface. The phosphine generator includes a metal phosphide feeding apparatus comprising a gas tight supply vessel containing a bed of particulate metal phosphide. The vessel is provided with a riser tube at the centre thereof. The inlet region of 5 the riser tube is perforated and faces a venturi nozzle connected to a propellant gas supply such as carbon dioxide. The top of the riser tube is connected to one of the subchambers through a valve or gate. The other subchamber is connected to a gas mixing chamber. Water in the chamber reacts with the metal phospide in particulate form to generate phosphine. Due to the phosphine generator being without wheels, it suffers from the drawbacks discussed earlier. Also the generator includes a large number of components and is bulky and expensive. OBJECTS OF THE INVENTION An object of the invention is to provide a portable fiimigator which is simple in construction and comprises less number of components and is compact and is also easy to operate and may be moved from place to place and taken to the fumigation site easily. Another object of the invention is to provide a portable fiimigator which operates at ambient conditions and does not require electric power or thermal energy for its operation 6 Another object of the invention is to provide a portable fumigator which is economical. DETAILED DESCRIPTION OF INVENTION According to the invention there is provided a portable fumigator comprising a gas tight reactor made of a mechanically strong corrosion resistant inert material and mounted on a frame provided with wheels and a handle, the reactor being provided with atleast one sight glass at the side thereof, the top of the reactor being provided with a carbon dioxide inlet line having a first flow control valve and flow indicator, a water inlet passage having a second flow control valve, a gas outlet fitted with an impingement column provided with a pressure sensor and a gas outlet line and a regulated metal phosphide tablet feeder and the bottom of the reactor being provided with a sludge outlet line having a valve. The following is a detailed description of the invention with reference to the accompanying schematic drawings, in which : Fig 1 is front view of a portable fumigator according to an embodiment of the invention; 7 Fig 2 is side view of the fumigator of Fig 1; Fig 3 is front view of the hopper of the fumigator of Fig 1; Fig 4 is top view of the hopper of Fig 3 without the lid; Fig 5 is bottom view of the hopper of Fig 3; Fig 6 is top view of the lid of the hopper of Fig 3; Fig 7 is side view of the rotary valve of the fumigator of Fig 1; Fig 8 is side view of the housing of the valve of Fig 7; Fig 9 is side view of the valve body and shaft of the valve of Fig 7; and Fig 10 is section at X-X in Fig 9. 8 The portable fumigator 1 as illustrated in Figs 1 to 10 of the accompanying drawings comprises a gas tight reactor 2 made of a mechanically strong corrosion resistant inert material such as stainless steel (Figs 1 and 2). The reactor 2 is mounted on a frame 3 provided with 3 wheels comprising 2 front wheels marked 4a,4a and a rear wheel marked 4b and a handle 5. The reactor is cylindrical shaped with a conical bottom marked 2a. The reactor is provided with a sight glass (window) 6 at the front side thereof. The reactor is further provided at the top surface 2b thereof with a carbon dioxide inlet line 7 having a first flow control valve 8 and flow indicator 9. The first flow control valve and flow indicator may be preferably a needle valve and rotameter, respectively. The carbon dioxide inlet line is connected to a carbon dioxide source (not shown). The reactor is also provided at the top surface thereof with a water inlet passage 10 having a second flow control valve 11. The mouth of the water inlet passage is funnel shaped marked 10a. The second flow control valve may be preferably a ball valve. The reactor is further provided at the top surface thereof with a gas outlet 12 fitted with an impingement column 13 provided with a pressure sensor 14 and a gas outlet line 15. The pressure sensor may be preferably a dial type pressure guage. The impingement column comprises a plurality of spaced baffles 16 located 9 internally opposite to one another in a staggered manner. The reactor is further provided at the top surface thereof with a regulated metal phosphide tablet feeder 17. It is to be understood that reference to tablet(s) wherever appearing in this specification includes pellet(s) and granule(s) also. The regulated metal phosphide tablet feeder comprises a hopper 18 whose mouth 18a is provided with a flange 18b having formed with a plurality of open slots 18c at the periphery thereof (Figs 1, 2, 3, 4 and 5). The mouth of the hopper is closed with a detachable lid 19 with a handle 20 (Figs 1, 2, 3, 4, 5 and 6). The lid is adapted to sit on the flange at the mouth of the hopper and is formed with a plurality of open slots 19a at the periphery thereof corresponding to the open slots in the flange at the mouth of the hopper. Wing nuts marked 21 are in thread engagement with bolts 22 pivoted on pins 23 which are anchored in pairs of spaced projections 24 extending down from the flange 18b at the mouth of the hopper. The lid is detachably fastened to the flange 18b by moving in the bolts 22 with wing nuts 21 about the pivot pins 23 and engaging the bolts in the corresponding open slots both in the flange at the mouth of the hopper and in the lid and tightening the wing nuts against the lid. The hopper is opened by removing or detaching the lid from the mouth of the hopper by loosening the wing nuts from the lid 10 and moving out the bolts 22 with the wing nuts 21 about the pivot pins 23 and disengaging the bolts from the corresponding open slots both in the flange at the mouth of the hopper and in the lid. The hopper is provided with a hollow stem 24 at the discharge end 18d thereof, which is mounted on the top surface of the reactor and having provided therein with a rotary valve 25 of known construction. The stem of the hopper comprises an upper part 24a and a lower part 24b. The rotary valve comprises a valve body 26 mounted on a shaft 27 which is provided with a handle 28 and is horizontally rotatably located in a valve housing 29 gas tight with the valve housing (Figs 7, 8 and 9). The upper part of the stem communicates with discharge opening 18e(Figs 4 and 5) at the discharge end of the hopper and the upper portion of the valve housing. The lower part of the stem communicates with the lower portion of the valve housing and the reactor. The valve body is provided with a pair of oppositely spaced grooves 30 along its peripheral surface facing the discharge opening 18e at the discharge end of the hopper and registering with the size and shape of the metal phosphide tablet(s) to be fed into the reactor (Fig 10). 31 is a sludge outlet line provided at the bottom of the reactor and having a valve 32 (Figs 1 and 2). 11 Water marked 33 is fed into the reactor via the water inlet passage. Supply of water into the reactor is controlled by the second flow control valve 11. Funnel shaped mouth of the water inlet passage facilitates the feeding of water into the reactor. The level of water in the chamber may be seen through the sight glass. The lid is removed from the mouth of the hopper as described earlier to feed metal phosphide tablets (not shown) into the hopper. After the metal phosphide tablets are fed into the hopper the hopper mouth is closed with the lid as described earlier. During manual rotation of the valve body at one position at 180 ° of rotation, one of the grooves 30 therein faces the discharge opening at the discharge end of the hopper and a metal phosphide tablet falls down from the hopper into the said one peripheral groove under gravity. At the same position, the other groove 30 in the valve body faces the water in the reactor and the metal phosphide tablet in that said other groove drops down into the water in the reactor under gravity. On rotating the valve body further by 1.80 ° manually, the said other groove in the valve body faces the discharge opening at the discharge end of the hopper and receives the metal phosphide tablet and the said one groove in the valve body faces the water in the reactor and drops the metal phosphide tablet therein into the water in the reactor. During 12 further rotation of the valve body the feeding of the metal phosphide tablets continue as described earlier. Water in the reactor reacts with the metal phosphide tablets to generate phosphine gas. Carbon dioxide gas at a pressure of 15 psi to 60 psi preferably 15 psi to 20 psi is fed into the reactor via the carbon dioxide inlet line. The inflow of carbon dioxide is controlled by the first flow control valve 8 and also metered by flow indicator 9. Carbon dioxide gas bubbles through the water in the reactor and stirs the water and aids dissolution of the metal phosphide tablets in the water and also the reaction between them. The carbon dioxide gas and phosphine gas in the reactor flow out into the impingement column. While the carbon dioxide and phosphine gas molecules move up in the impingement column, they impinge against the baffles which obstruct and regulate the flow of the gases and aid the gases molecules to mix together. Due to the staggered nature of the baffles obstruction and flow regulation of the gases is very effective. The pressure sensor monitors the gas pressure in the impingement column. In case the gas pressure in the impingement column increases as read on the pressure sensor the reaction between water and metal phosphide tablets and phosphine generation is controlled by controlling the feed rate of the metal phosphide tablets into the reactor. The 13 phosphine and carbon dioxide gas mixture is led to the fumigation site through the gas outlet line 15 of the impingement column. The carbon dioxide inflow is controlled so as to maintain the ratio of carbon dioxide gas and phosphine gas between 100 : 3 preferably 100 : 2. The sludge / sediments at the bottom of the reactor is drained out by opening valve 32. The conical shaped bottom of the reactor facilitates drainage of the sludge / sediments. The movement of the fumigator of the invention fromjplace to place is easy due to the provision of the wheels. Therefore, the fumigator may be easily moved to the fumigation site obviating the necessity of having to collect and transport phosphine to the fumigation site. The fumigator comprises less number of components and is compact and is also simple in construction. It operates at ambient conditions and does not require any electric or thermal energy for its-operation. It is also economical for the above reasons. There may be modifications / variations in the above embodiment of the invention without deviating from the scope of the invention. For instance, the frame may be of a different geometry or construction. Instead 14 of 3 wheels, the frame may be provided with 2 or 4 wheels. The reactor may be of any other geometry besides being cylindrical with conical bottom. The sight glass is optional. There may be more than one sight glass. The location of the sight glass may vary and it may even be provided in the lid. The first and second flow conrroi valves also may be gate valve or globe valve. The flow meter also may be other known gas flow meters. The mouth of the water inlet passage may not be funnel shaped. The pressure sensor also may be digital pressure indicator, piston gauge or diaphragm seal type pressure gauge. The impingement column may be of a different construction. The regulated metal phosphide tablet feeder may be of a different construction. There may be more number of grooves along the peripheral surface of the valve body for the metal phosphide tablets. Such variations of the invention are obvious modifications and improvements and are to be construed and understood to be within the scope of the invention. 15 WE CLAIM: 1. Portable fumigator comprising a gas tight reactor made of a mechanically strong corrosion resistant inert material and mounted on a frame provided with wheels and a handle, the reactor being provided with atleast one sight glass at the side thereof, the top of the reactor being provided with a carbon dioxide inlet line having a first flow control valve and flow indicator, a water inlet passage having a second flow control valve, a gas outlet fitted with an impingement column provided with a pressure sensor and a gas outlet line and a regulated metal phosphide tablet feeder and the bottom of the reactor being provided with a sludge outlet line having a valve. 2) Portable fumigator as claimed in claim 1, wherein the reactor is made of a mechanically strong corrosion resistant inert material such as stainless steel. 3) Portable fumigator as claimed in claim 1 or 2, whose frame is provided with 3 wheels comprising 2 front wheels and a rear wheel. 16 4) Portable fumigator as claimed in any one of claims 1 to 3, wherein the reactor is cylindrical shaped with a conical bottom. 5) Portable fumigator as claimed in any one of claims 1 to 4, wherein the first flow control valve is a needle valve and the flow indicator is a rotameter. 6) Portable fumigator as claimed in any one of claims 1 to 5, wherein the mouth of the water inlet passage is funnel shaped and the second flow control valve is a ball valve. 7) Portable fumigator as claimed in any one of claims 1 to 6, wherein the pressure sensor is dial type pressure gauge. 8) Portable fumigator as claimed in any one of claims 1 to 7, wherein the impingement column comprises a plurality of spaced baffles located internally opposite to one another in a staggered manner. 9) Portable fumigator as claimed in any one of claims 1 to 8, wherein the regulated metal phosphide tablet feeder comprises a hopper 17 whose mouth is closed with a detachable lid with handle, the hopper being provided with a hollow stem at the discharge end thereof, which is mounted on the top surface of the reactor and having provided therein with a rotary valve. 10) Portable fumigator as claimed in claim 9, wherein the mouth of the hopper is provided with a flange having formed with a plurality of open slots at the periphery thereof, the lid is adapted to sit on the flange at the mouth of the hopper and formed with a plurality of open slots at the periphery thereof corresponding to the open slots in the flange at the mouth of the hopper, the lid being detachably tightened against the flange at the mouth of the hopper by wing nuts in thread engagement with bolts which are pivoted at the mouth of the hopper and are engageable in the open slots in the flange at the mouth of the hopper and the lid so as to facilitate tightening of the wing nuts on the lid. 11) Portable fumigator as claimed in claim 9 or 10, wherein the stem of the hopper comprises an upper part and a lower part and the rotary valve comprises a valve body mounted on a shaft which is provided 18 with a handle and is horizontally rotatably located in a valve housing, the valve body being gas tight with the valve housing, the upper part of the stem communicating with the discharge opening at the discharge end of the hopper and the upper portion of the valve housing and the lower part of the stem communicating with the lower portion of the valve housing and the reactor, the valve body being provided with at least one pair of oppositely spaced grooves along its peripheral surface facing the discharge opening at the discharge end of the hopper and registering with the size and shape of metal phosphide tablet(s) to be fed into the reactor. 12) Portable fumigator substantially as herein described particularly with reference to the accompanying drawings. Dated this 17th day of June 2004 (Jose M A) " of Khaitan & Co Agent for the Applicants

Documents:

667-mum-2004-abstract(28-02-2005).doc

667-mum-2004-abstract(28-02-2005).pdf

667-mum-2004-cancelled pages(28-02-2005).pdf

667-mum-2004-claims(granted)-(28-02-2005).doc

667-mum-2004-claims(granted)-(28-02-2005).pdf

667-mum-2004-correspondence(03-10-2006).pdf

667-mum-2004-correspondence-(ipo)-(09-11-2004).pdf

667-mum-2004-drawing(18-06-2004).pdf

667-mum-2004-form 1(09-08-2004).pdf

667-mum-2004-form 1(18-06-2004).pdf

667-mum-2004-form 19(06-08-2004).pdf

667-mum-2004-form 2(granted)-(28-02-2005).doc

667-mum-2004-form 2(granted)-(28-02-2005).pdf

667-mum-2004-form 26(09-08-2004).pdf

667-mum-2004-form 3(18-06-2004).pdf

667-mum-2004-form 8(06-08-2004).pdf

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