Description:FIELD
The present disclosure relates to a system and a process for coating a fertilizer. Particularly the present disclosure relates to a system and a process for coating urea with sulphur.
DEFINITIONS
As used in the present disclosure, the following term is generally intended to have the meaning as set forth below, except to the extent that the context in which it is used indicate otherwise.
Prills: The term “prills” refers to small, spherical or granular pellets of a substance. The term is commonly used in the context of certain chemical or industrial products, such as fertilizers.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Urea is a nitrogen-containing compound commonly used as a fertilizer in agriculture. It is a white, crystalline substance that contains about 46% nitrogen by weight, thereby making it one of the highest nitrogen-content fertilizers. Nitrogen is an essential nutrient for plant growth, and urea is a widely used nitrogen source.
Urea is often used as such, but also as a component of a particulate blend, i.e. a physical blend or bulk blend, containing additional (primary and secondary nutrient) elements, such as potassium, phosphorus, nitrogen and sulphur to obtain a particulate NPK(S), NP(S) or NK(S) blend, and other elements such as magnesium and calcium (secondary nutrients). Although urea is popular due to its high nitrogen content, solubility, and versatility in application methods, urea is susceptible to nitrogen volatilization, a process in which ammonia gas is released into the atmosphere. This can occur when urea comes into contact with urease enzymes in the soil, leading to the rapid conversion of urea to ammonia. Nitrogen loss through volatilization reduces the efficiency of the fertilizer and can contribute to air pollution. Urea dissolves readily in water, which can lead to rapid nutrient leaching. In areas with heavy rainfall or over-irrigation, the nitrogen in urea may be washed away from the soil, reducing its availability to plants and potentially contributing to water pollution. In some cases, direct contact between uncoated urea and plant tissues, especially under certain environmental conditions like high temperatures or humidity, can lead to nitrogen burn. This occurs when ammonia gas is released and damages plant tissues.
Therefore, there is felt a need to provide a system and a process for producing coated fertilizer that mitigates the aforesaid drawbacks or at least provide a useful alternative.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
An object of the present disclosure is to ameliorate one or more problems of the background or to at least provide a useful alternative.
Another object of the present disclosure is to provide a system for coating fertilizer.
Another object of the present disclosure is to provide a system for coating urea with sulphur.
Yet another object of the present disclosure is to provide a process for coating a fertilizer which is simple and efficient.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY
The present disclosure relates to a system for coating a fertilizer, comprising:
• a heating chamber configured to receive at least one fertilizer to obtain a heated fertilizer;
• a first melting vessel configured to receive a first coating agent to generate a molten stream of the first coating agent;
• at least one first coater is in communication with the heating chamber to receive the heated fertilizer;
• at least one first header mounted with at least one first nozzle, the first header configured to be fitted in the at least one first coater in fluid communication with the first melting vessel to receive the molten stream of the first coating agent, wherein the at least first nozzle sprays the molten stream of the first coating agent over the heated fertilizer to obtain a first coated fertilizer.
• a second melting vessel configured to receive a second coating agent to generate a molten stream of the second coating agent;
• at least one second coater is in communication with the first coater to receive the first coated fertilizer;
• at least one second header mounted with at least one second nozzle, the second header configured to be fitted in at least one second coater and in fluid communication with the second melting vessel to receive the molten stream of the second coating agent, wherein the at least second nozzle sprays the molten stream of the second coating agent over the first coated fertilizer to obtain a coated fertilizer.
In an embodiment of the present disclosure, the heating chamber is at least one selected from a rotary drum heater, pan coater, and fluidized bed reactor.
In an embodiment of the present disclosure, the fertilizer is heated in the heating chamber through a co-current hot air at a flow rate in the range of 400 m3/hour to 450 m3/hour.
In an embodiment of the present disclosure, the hot air is generated by an external inline electric air heater.
In an embodiment of the present disclosure, a hot air temperature at the inlet and at the outlet of the heating chamber is in the range of 140 °C to 170 °C and 50 °C to 70 °C respectively.
In an embodiment of the present disclosure, the melting vessels are steam jacketed, and the melting vessels are configured with a steam coil and an agitator.
In an embodiment of the present disclosure, the steam exerts a pressure in the range of 2 kg/cm2 to 8 kg/cm2 for heating the first coating agent and the second coating agent in the melting vessels.
In an embodiment of the present disclosure, a plurality of plunger-type pumps are configured downstream of the first melting vessel for the dozing the molten stream of the first coating agent to the at least one first header.
In an embodiment of the present disclosure, the first coater and the second coater is at least one independently selected from a rotary drum coater, pan coater, fluidized bed reactor, wherein the coaters are rotated at a speed in the range of 10 rpm to 15 rpm.
In an embodiment of the present disclosure, the first header and the second header are steam jacketed having a steam inlet port and a condensate port, wherein the steam inlet and the condensate outlet ports are having flexible connections to facilitate nozzle spray angle adjustment.
In an embodiment of the present disclosure, the first nozzle and the second nozzle are steam jacketed.
In an embodiment of the present disclosure, the first nozzle and the second nozzle is configured with a plurality of fine holes at an operative outer surface, to pass a stream of hot air for the atomization of the first coating agent and the second coating agent.
In an embodiment of the present disclosure, the stream of hot air has a flow rate in the range of 0.3 m2/hour to 1.5 m3/hour and a pressure in the range of 1 kg/cm2 to 4 kg/cm2 for atomizing of the coating agents.
In an embodiment of the present disclosure, the first nozzle and the second nozzle configured with an inlet flange, the inlet flanges are extended angularly from an operative surface of the header to facilitate the spray adjustment by rotating the header.
In an embodiment of the present disclosure, a cooler is configured downstream of the second coater, the cooler is in communication with the second coater to receive the coated fertilizer to obtain a cooled coated fertilizer.
In an embodiment of the present disclosure, a segregator is configured downstream of the cooler, the segregator is in communication with the cooler to receive the cooled coated fertilizer to obtain fertilizer in the form of prills having a predetermined diameter.
In an embodiment of the present disclosure, the predetermined diameter of the prills is in the range of 1 mm to 4 mm.
In another aspect the present disclosure provides a process for coating a fertilizer, the process comprising the following steps:
a) pre-heating a fertilizer to a temperature in a range of 50 °C to 60 °C to obtain a heated fertilizer;
b) separately heating a first coating agent to a temperature in the range of 130 °C to 145 °C first molten coating agent;
c) spray coating the heated fertilizer by using the first molten stream of coating agent to obtain a first coated fertilizer;
d) separately heating a second coating agent at a temperature in the range of 60 °C to 80 °C followed by spray coating over the first coated fertilizer to obtain a coated fertilizer; and
e) cooling the coated fertilizer and drying in air followed by segregating the dried fertilizer to obtain coated fertilizer having predetermined diameter.
In an embodiment of the present disclosure, the first coating agent is selected from the group consisting of sulphur, a polymer, a mineral oil, beewax, sodium oleate, shellac formulation, ethylene oxide, and higher fatty alcohols.
In an embodiment of the present disclosure, the polymer is at least one selected from the group consisting of paraffin wax and microcrystalline wax.
In an embodiment of the present disclosure, the second coating agent is selected from the group consisting of a polymer, mineral oil, beewax, sodium oleate, shellac formulation, ethylene oxide, and higher fatty alcohols. In an exemplary embodiment the second coating agent is microcrystalline wax.
In an embodiment of the present disclosure, the polymer is at least one selected from the group consisting of paraffin wax and microcrystalline wax.
In an embodiment of the present disclosure, coated fertilizer is sulphur coated urea fertilizer, characterized by having 37% Nitrogen and 17% sulphur and wherein the coated fertilizer is in the form of a prill having a diameter in the range of 2 mm to 3 mm.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a schematic representation of the system (100) in accordance with the present disclosure, wherein (110) represents first flow line, (174) represents a fertilizer, (112) represents a heating chamber, (120) represents first melting vessel, (128) pumps, (126) represents a second flow line, (130) represents first coater, (134a) represents proximal first header, (134b) represents distal first header, (136a) represents proximal second headers, (136b) represents distal second headers, (140) represents spray nozzles, (142) represents heated atomizing air, (150) represents a second coater, (166) represents a second coating agent, (162) represents second melting vessel, and (160) represents a cooler, (167) represents a segregator;
Figure 2 illustrates a first header (134) in accordance with the present disclosure, wherein (142) represents atomizing air, (137) represents steam inlet port, (138) represents condensate outlet port, (139) represents plug, and (170) represents a first molten coating composition,
Figure 3 illustrates a lateral view of the first header (134) in accordance with the present disclosure;
Figure 4 illustrates a jacketed first nozzle (140) in accordance with the present disclosure, wherein (141) represents fine holes, (143) represents outlet, (142) represents atomizing air, (170) represents molten stream of the first coating agent, (171) represents steam, and (172) represents condensate;
Figure 5a illustrates a non jacketed first nozzle (140a) in accordance with the present disclosure, wherein (141) represents fine holes, and (143) represents the outlet ;
Figure 5b illustrates a lateral view of a non jacketed first nozzle (140a) in accordance with the present disclosure, herein (141) represents fine holes, and (143) represents the outlet; and
Figure 6 illustrates a second nozzle (152) in accordance with the present disclosure, wherein (173) represents the second coating agent, and (142) represents atomizing air.
LIST OF REFERENCE NUMERALS
100 – a system for producing coated fertilizer
110 – first flow line
112 – heating chamber
120 – first melting vessel
126 – second flow line
128 – pump
130 – first coater
134 – first headers
134a – proximal first header
134b – distal first header
136 – second headers
136a - proximal second header
136b - distal second header
137 – steam inlet port
138 – condensate port
139 – plug
140 – first nozzles
140a – non jacketed sulphur coating nozzle
141 – fine holes
142 – heated atomizing air
143 – outlet
150 – second coater
152 – second nozzles
155 – third flow line
156 – fourth flow line
160 – cooler
162 – second melting vessel
165 – first coating agent
166 – second coating agent
167 – segregator
170 – molten stream of first coating agent
171 – steam
172 – condensate
173 – molten stream of second coating agent
174 - fertilizer
DETAILED DESCRIPTION
The present disclosure relates to a system and a process for coating a fertilizer. Particularly the present disclosure relates to a system and a process for producing sulphur coated fertilizer.
Embodiments of the present disclosure will now be described with reference to the accompanying drawings.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Urea is a nitrogen-containing compound commonly used as a fertilizer in agriculture. It is a white, crystalline substance that contains about 46% nitrogen by weight, thereby making it one of the highest nitrogen-content fertilizers. Nitrogen is an essential nutrient for plant growth, and urea is a widely used nitrogen source.
Urea is often used as such, but also as a component of a particulate blend, i.e. a physical blend or bulk blend, containing additional (primary and secondary nutrient) elements, such as potassium, phosphorus, nitrogen and sulphur to obtain a particulate NPK(S), NP(S) or NK(S) blend, and other elements such as magnesium and calcium (secondary nutrients). Although urea is popular due to its high nitrogen content, solubility, and versatility in application methods, urea is susceptible to nitrogen volatilization, a process in which ammonia gas is released into the atmosphere. This can occur when urea comes into contact with urease enzymes in the soil, leading to the rapid conversion of urea to ammonia. Nitrogen loss through volatilization reduces the efficiency of the fertilizer and can contribute to air pollution. Urea dissolves readily in water, which can lead to rapid nutrient leaching. In areas with heavy rainfall or over-irrigation, the nitrogen in urea may be washed away from the soil, reducing its availability to plants and potentially contributing to water pollution. In some cases, direct contact between uncoated urea and plant tissues, especially under certain environmental conditions like high temperatures or humidity, can lead to nitrogen burn. This occurs when ammonia gas is released and damages plant tissues.
To overcome these limitations fertilizer particles can be “doped” or coated with elemental sulphur in sulphur-deficient soils. The sulfur coating acts as a barrier, slowing down the release of nitrogen from the fertilizer. This gradual release provides a more sustained and controlled supply of nitrogen to plants over an extended period, reducing the risk of nutrient loss through leaching and volatilization. The sulfur coating also helps minimize nitrogen loss by slowing down the conversion of fertilizer to ammonia resulting in minimize the environmental impact associated with nitrogen fertilizers.
The present disclosure provides a system (100) for coating a fertilizer, the system comprising:
The present disclosure provides a system for coating a fertilizer, comprising:
• a heating chamber (112) configured to receive at least one fertilizer (174) to obtain a heated fertilizer;
• a first melting vessel (120) configured to receive a first coating agent (165) to generate a molten stream of the first coating agent (170);
• at least one first coater (130) is in communication with the heating chamber (112) to receive the heated fertilizer;
• at least one first header (134) mounted with at least one first nozzle (140), the first header configured to be fitted in at least one first coater (130) and in fluid communication with the first melting vessel (120) to receive the molten stream of the first coating agent (170), wherein the at least first nozzle (140) sprays the molten stream of the first coating agent (170) over the heated fertilizer to obtain a first coated fertilizer.
• a second melting vessel (162) configured to receive a second coating agent (166) to generate a molten stream of the second coating agent (173);
• at least one second coater (150) is in communication with the first coater (130) to receive the first coated fertilizer;
• at least one second header (136) mounted with at least one second nozzle (152), the second header (136) configured to be fitted in the at least one second coater (150) and in fluid communication with the second melting vessel (162) to receive the molten stream of the second coating agent (173), wherein the at least second nozzle (152) sprays the molten stream of the second coating agent (173) over the first coated fertilizer to obtain a coated fertilizer.
In an embodiment of the present disclosure, the heating chamber (112) is at least one selected from a rotary drum heater, fluidised bed reactor, and pan coater. In an exemplary embodiment of the present disclosure, the heating chamber is a rotary drum heater.
In an embodiment of the present disclosure, the fertilizer (174) is heated in the heating chamber (112) through a co-current hot air at a flow rate in the range of 400 m3/hour to 450 m3/hour. In an exemplary embodiment, the flow rate is 420 m3/hour.
In an embodiment of the present disclosure, the hot air is generated by an external inline electric air heater.
In an embodiment of the present disclosure, a hot air temperature at an inlet and at an outlet of the heating chamber is in the range of 140 °C to 170 °C and 50 °C to 70 °C respectively. In an exemplary embodiment of the present disclosure, the hot air temperature at the inlet is around 150 to 160 °C and the hot air temperature at the outlet is around 55 to 65 °C.
In an embodiment of the present disclosure, the melting vessels (120 and 162) are steam jacketed, and the melting vessels are configured with a steam coil and an agitator.
In an embodiment of the present disclosure, the steam exerts a pressure in the range of 2 kg/cm2 to 8 kg/cm2 for heating the first coating agent and the second coating agent in the melting vessels. In an exemplary embodiment of the present disclosure, the steam exerts a pressure of 6 kg/cm2.
In an embodiment of the present disclosure, a plurality of plunger-type pumps (128) are configured downstream of the first (120) and second melting vessels (162) for dozing the molten stream of the first coating agent to the at least one first header. In an exemplary embodiment, the pump (128) is having a stroke adjustment and RPM control through variable frequency drives (VDF) to facilitate precise and metered control of the first coating agent.
In an embodiment of the present disclosure, a plurality of pumps provide for each header and nozzle. This facilitates precise and independent spray control on each nozzle and there is no need of separate orifice at nozzle inlet for metering.
In an embodiment of the present disclosure, the pump has a capacity of 0 to 400 kg/hour and head of around 2 kg/cm2. Complete pipelines at pump suction and discharge into headers are steam jacketed.
In an embodiment of the present disclosure, the first coater (130) and the second coater (150) are at least one independently selected from a rotary drum, a pan coater, and a fluidised bed reactor.
In an embodiment of the present disclosure, the coaters (130 and 150) are rotated at a speed in the range of 10 rpm to 15 rpm. In an exemplary embodiment of the present disclosure, the coaters are operated at a speed of 12 rpm to 13.5 rpm.
In an embodiment of the present disclosure, the coaters are provided with inverted angles from inside to facilitate rolling and shuffling of the fertilizer. The coaters are provided with baffle arrangement from inside. This assists uniform coating of the molten first coating agent on the fertilizer all over. Two retaining rings are provided inside the coater and at discharge side of each nozzle to help formation of a fertilizer bed. In an exemplary embodiment the height of the retaining ring is around 65 to 70 mm.
In an embodiment of the present disclosure, the first header (134) and the second header (136) are steam jacketed having a steam inlet port (137) and a condensate port (138), wherein the steam inlet port (137) and the condensate port (138) are having flexible connections to facilitate nozzle angle adjustment.
In an embodiment of the present disclosure, the first nozzle (140) and the second nozzle (152) are steam jacketed.
In an embodiment of the present disclosure, the first (140) and second nozzles (152) are not steam jacketed.
In an embodiment of the present disclosure, the first nozzle and the second nozzle are configured with a plurality of fine holes (141) at an operative outer surface, to pass a stream of hot air for the atomization of the first coating agent and the second coating agents. In an exemplary embodiment, the first nozzle (140) and the second nozzle (152) are configured with 8 fine holes at an operative outer surface to pass a stream of hot air for the atomization of the first and second coating agents.
In an embodiment of the present disclosure, the stream of hot air has a flow rate in the range of 0.3 m3/hour to 1.5 m3/hour and a pressure in the range of 1 kg/cm2 to 4 kg/cm2 for atomizing of the coating agents. In an exemplary embodiment, the stream of hot air has a flow rate of 0.54 m3/hour to 1 m3/hour and a pressure of 2.1 kg/cm2 to 2.45 kg/cm2 for atomizing of the coating agents.
In an embodiment of the present disclosure, the first nozzle (140) and the second nozzle (152) are configured with an inlet flange (not numbered), the inlet flanges are extended angularly from an operative surface of the header to facilitate the spray adjustment by rotating the header. The inlet flange is configured at a predetermined inward angle such that a slot is defined by the flange to facilitate spray adjustment by rotating the header.
In an embodiment of the present disclosure, a cooler (160) is configured downstream of the second coater (150), the cooler (160) is in communication with the second coater (150) to receive the coated fertilizer to obtain a cooled coated fertilizer.
In an embodiment of the present disclosure, the cooler is rotary drum type air cooler.
In an embodiment of the present disclosure, a segregator (167) is configured downstream of the cooler (160), the segregator (167) is in communication with the cooler (160) to receive the cooled coated fertilizer in the form of prills having a predetermined diameter.
In an embodiment of the present disclosure, the predetermined diameter of the fertilizer prills is in the range of 1 mm to 4 mm. In an exemplary embodiment of the present disclosure, the predetermined diameter of the fertilizer prills is 2 to 3 mm.
In another aspect the present disclosure provides a process for coating a fertilizer, the process comprising the following steps:
a) pre-heating a fertilizer (174) to a temperature in the range of 50 °C to 60 °C to obtain a heated fertilizer;
b) separately heating a first coating agent (165) to a temperature in the range of 130 °C to 145 °C to obtain a molten stream of first coating agent (170);
c) spray coating the heated fertilizer by using the molten stream of first coating agent (170) to obtain a first coated fertilizer;
d) separately heating a second coating agent (166) at a temperature in the range of 60 °C to 80 °C followed by spray coating over the first coated fertilizer to obtain a coated fertilizer; and
e) cooling the coated fertilizer and drying in air followed by segregating the dried coated fertilizer to obtain the coated fertilizer having predetermined diameter.
In an embodiment of the present disclosure, the first coating agent is selected from the group consisting of sulphur, a polymer, mineral oil, beewax, sodium oleate, shellac formulation, ethylene oxide, and higher fatty alcohols.
In an embodiment of the present disclosure, the polymer is at least one selected from the group consisting of paraffin wax and microcrystalline wax.
In an exemplary embodiment the first coating agent is sulphur.
In an embodiment of the present disclosure, the second coating agent is selected from the group consisting of a polymer, mineral oil, beewax, sodium oleate, shellac formulation, ethylene oxide, and higher fatty alcohols. In an exemplary embodiment the second coating agent is microcrystalline wax.
In an embodiment of the present disclosure, the polymer is at least one selected from the group consisting of paraffin wax and microcrystalline wax. In an exemplary embodiment the polymer is and microcrystalline wax.
In an exemplary embodiment the fertilizer is heated at 56 °C.
In an exemplary embodiment the first coating agent is heated at 138 °C.
In an embodiment of the present disclosure, coated fertilizer is sulphur coated urea fertilizer, characterized by having 37% Nitrogen and 17% sulphur and wherein said coated fertilizer is in the form of a prill having diameter in the range of 2 mm to 3 mm.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Experiment 1: A process for coating urea prills with sulphur in accordance with the present disclosure
Step 1: Urea feeding and preheating
Urea of prill size 1.5 mm was manually fed into the hopper of around 300 kg capacity at inlet of bucket type urea feed conveyor. The bucket conveyor discharges the urea to 400 kg hopper above scale feeder. From the hopper, urea was conveyed to rotary drum type heating chamber (112) at a controlled rate through scale feeder which was having capacity of 1.5 MT per hour. In the rotary drum type heating chamber (112), urea was heated by co-current hot air flow to obtain heated urea. Hot air for heating urea was generated by external inline electric air heater. Air temperature at inlet and outlet of the rotary drum type heating chamber (112) was around 150 °C to 160 °C and 55 °C to 65 °C, respectively. The urea was heated up to 50 °C to 55 °C in the rotary drum type heater (112). The heated urea was then discharged to sulphur coater second vessel (130) by gravity flow.
Step 2: sulphur melting and transfer
The sulphur was fed to the first melting vessel (120) from top manually and melted in the vessel of around 2 kiloliter capacity. Steam was passed through the jacket over the first vessel at a pressure of 6 kg/cm2 to obtain molten sulphur. The so obtained molten sulphur was transferred to a first coater (130) by a pump having a capacity of 0 to 400 kg/ hour and head of around 2 kg/cm2. Complete pipelines head of around 1.5 to 2 kg/cm2, at pump section up to sulphur spray header were jacketed. The steam was maintained at 6 kg/m2 in the jacket to maintain the molten sulphur within desired temperature range (135 °C to 140 °C).
Step 3: sulphur coating
Sulphur was fed to each nozzle (140) by separate pump (128). The molten sulphur was atomized by heated atomizing air at a pressure of 2 to 3 kg/cm2. The atomizing air was heated by electric pre-heater. The air comes out of the newly developed non jacketed nozzle from 8 number fine holes around the sulphur outlet. The air atomized the sulphur and gave fine spray and uniform coating to the urea prills coming from the heating chamber (112) to obtain a first coated urea.
Step 4: Wax melting, transfer and coating
The wax was fed from top manually and melted in a second melting vessel (162) of around 100 liter capacity. The vessel was steam jacketed. A steam coil was also provided inside the tank. For uniform heating an agitator was provided on the tank. Temperature was maintained at 70 °C. The so obtained molten wax thus obtained was transferred to the second coater by a rotary gear type pump. The pump was provided with RPM control through VFD and a recirculation line. Isolation valves were provided on both transfer and recirculation lines. This arrangement facilitated precise and metered control of wax quantity in spray. Complete pipelines along with the transfer pump and spray header were steam jacketed to maintain the wax in molten phase. One number nozzle of 1 mm bore was used for wax coating. The nozzle had atomizing air provision for uniform coating. The first coated fertilizer obtained in step 3 was passed into the second coater (150) for wax coating to obtain a coated fertilizer.
The coated fertilizer was passed through rotary drum type cooler (160) with concurrent flow of ambient air. The product was further passed through a segregator (167) to segregate over size, under size and proper size wax and sulphur coated fertilizer prills. The sieve was double deck, vibratory type sieve which separated proper size prills of 2-3 mm which were further packed.
The sulphur coated fertilizer, a slow release fertilizer has 37% nitrogen and 17% sulphur. The coating of urea with molten sulphur is the crux and spine of the present disclosure. Sulphur has typical characteristics of being molten within the range of 130 °C to 144 °C and becomes solid after 144 °C. It is necessary to keep the sulphur in molten form and allow a continuous molten stream or fine mist of molten sulphur to coat over the fertilizer prills.
In order to get a continuous mist of molten sulphur the header and the nozzles are designed in such a way to achieve the required grade and the rate of the production of sulphur coated fertilizer to 1.5 MT per hour. The system in accordance with the present disclosure is further extrapolated to a higher scale of production in a commercial plant. The most innovative part of the present disclosure is the header placement, it design and also with the nozzle and its design for spray of molten sulphur.
Table 1 summarizes the difference between a comparative system and the system in accordance with the present disclosure.
Comparative System System in accordance with the present disclosure
Design Capacity 1 TPH 1.5 TPH

Raw Material Urea Granular Urea Prilled Urea: Size around 2 mm

Equipment Preheater Rotary drum (Insulated outside, smooth inside) Rotary drum (smooth inside with shield over air inlet pipe)
Size: 2 feet Diameter X 6.5 Ft Long Size: 0.9 meter Diameter X 4 meter Long
Heated by resistance radiant type heaters mounted inside Heated by hot air from electric air pre-heater
Urea outlet temperature: 145-150 F (62-65 Deg C) Urea outlet temperature:56- 60 °C

Sulphur coater Rotary drum (Insulated outside, smooth inside) Rotary drum (Tumblers inside. Shield over header)
Size: 4 feet Diameter X 6 Ft Long Size: 1.2 meter Diameter X 4 meter long
Atomizing air: steam heated by heat exchanger Atomizing air: heated by electric pre-heater
Pump: Hydraulic operated Diaphragm pump Pump: Plunger type dosing pump
Metering: mainly by scale based tank Metering: by dosing pump discharge adjustment and VFD
Spray nozzle: 8 numbers on one header Spray nozzle: 2 numbers (Total two headers, 1 Nozzle on one header). One header on each end of drum. Each header has provision for 2 or more nozzles.
Orifice: at each nozzle inlet for equal metering Orifice Not provided
Nozzle opening: 0.052 inch 3 and 4 mm (adjustment for various nozzle size feasible)
Spray vertically down: 4-3/4 inch gap Spray gap around 250 mm
Discharge Retaining ring: 3-3/8 inch height Two retaining rings at discharge side of each nozzle. Each of 65-70 mm height
No flights inside Tumblers / baffle provided inside
Nozzle design: with wing only atomizing air from side, separate removable part at outlet for different sulphur outlet opening size

Sulphur tank Scale mounted tank Floor mounted. Level based
Heating: steam coil inside Steam coil inside, steam jacket outside
Agitator provided. For quick and uniform heating

Wax coater Rotary drum (Insulated outside, smooth inside) Rotary drum (smooth inside)
Size: 3 feet Diameter X 2 Ft Long Size: 0.9 meter Diameter X 4 meter Long
Pump: Diaphragm pump Pump: rotary gear type with recycle line for fine control
Cooler Fluid bed type - air cooled Rotary drum type, air cooled
(bed area: 10 Square feet area) Size: 0.9 meter Diameter X 4 meter Long

Conditioner coater Size: 4 feet Diameter X 3 Ft Long Size: 0.9 meter Diameter X 4 meter Long

Screen 4 mm mesh 2 mm and 3 mm size

In accordance with the system of the present disclosure, the spray angle can be adjusted by rotating the header along the axis with help of the slots provided in header inlet sulphur flange. Flexible connections are provided in steam inlet and condensate outlet to facilitate nozzle angle adjustment. The sulphur outlet bore size in the nozzle is 3 mm. Sulphur is fed to each nozzle by separate pump. As such total two separate pumps are used, one for each header and nozzle. This facilitates precise and independent spray control on each nozzle and there is no need of separate orifice at nozzle inlet. Increased sulphur outlet bore size and elimination of orifice further reduces sulphur choking / clogging at nozzle inlet.
TECHNICAL ADVANCEMENTS
The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of:
A system and a process for coating fertilizer prills, that:
• is simple and efficient;
• provides sulphur coated fertilizer prills in the range of 1 mm to 4 mm;
• can be utilized for any fertilizer;
• can be utilized to coat fine granular fertilizer products; and
• can be utilized for coating slow release fertilizers through polymers.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising, will be understood to imply the inclusion of a stated element, integer or step,” or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
The economy significance details requirement may be called during the examination. Only after filing of this Patent application, the applicant can work publically related to present disclosure product/process/method. The applicant will disclose all the details related to the economic significance contribution after the protection of invention. , Claims:WE CLAIM:
1. A system (100) for coating fertilizers comprising:
• a heating chamber (112) configured to receive at least one fertilizer (174) to obtain a heated fertilizer;
• a first melting vessel (120) configured to receive a first coating agent (165) to generate a molten stream of said first coating agent (170);
• at least one first coater (130) is in communication with said heating chamber (112) to receive said heated fertilizer;
• at least one first header (134) mounted with at least one first nozzle (140), said first header configured to be fitted in said at least one first coater (130) and in fluid communication with said first melting vessel (120) to receive said molten stream of said first coating agent (170), wherein said at least first nozzle (140) sprays said molten stream of said first coating agent (170) over said heated fertilizer to obtain a first coated fertilizer.
• a second melting vessel (162) configured to receive a second coating agent (166) to generate a molten stream of said second coating agent (173);
• at least one second coater (150) is in communication with said first coater (130) to receive said first coated fertilizer;
• at least one second header (136) mounted with at least one second nozzle (152), said second header (136) configured to be fitted in said at least one second coater (150) and in fluid communication with said second melting vessel (162) to receive said molten stream of said second coating agent (173), wherein said at least second nozzle (152) sprays said molten stream of said second coating agent (173) over said first coated fertilizer to obtain said coated fertilizer.
2. The system as claimed in claim 1, wherein said heating chamber (112) is at least one selected from a rotary drum heater, a pan coater, and a fluidized bed reactor.
3. The system as claimed in claim 1, wherein
• said fertilizer (174) is heated in said heating chamber (112) through a co-current hot air at a flow rate in the range of 400 m3/hour to 450 m3/hour, wherein said hot air is generated by an external inline electric air heater; and
• a hot air temperature at an inlet and at an outlet of said heating chamber is in the range of 140 °C to 170 °C and 50 °C to 70 °C respectively.
4. The system as claimed in claim 1, wherein
• said melting vessels (120 and 162) are steam jacketed and said melting vessels are configured with a steam coil and an agitator; and
• said steam exerts a pressure in the range of 2 kg/cm2 to 8 kg/cm2 for melting said first coating agent and second coating agent in said melting vessles.
5. The system as claimed in claim 1, wherein a plurality of plunger-type pumps (128) are configured downstream of said first melting vessel for dozing said molten stream of said first coating agent to said at least one first header (134).
6. The system as claimed in claim 1, wherein said first coater (130) and said second coater (150) is at least one independently selected from a rotary drum coater, a pan coater, and a fluidized bed reactor.
7. The system as claimed in claim 1, wherein said first header (134) and said second header (136) are steam jacketed having a steam inlet port (137) and a condensate port (138), wherein said steam inlet port (137) and said condensate port (138) are having flexible connections to facilitate nozzle angle adjustment.
8. The system as claimed in claim 1, wherein said first nozzle (140) and said second nozzle (152) are steam jacketed.
9. The system as claimed in claim 1, wherein said first nozzle (140) and said second nozzle (152) are configured with plurality of fine holes (141) at an operative outer surface, to pass a stream of hot air (142) for the atomization of said first coating agent and said second coating agent.
10. The system as claimed in claim 1, wherein said stream of hot air (142) has a flow rate in the range of 0.3 to 1.5 m3/hour and a pressure in the range of 1 kg/cm2 to 4 kg/cm2 for atomizing of said coating agents.
11. The system as claimed in claim 1, wherein said first nozzle (140) and said second nozzle (152) are configured with an inlet flange, said inlet flanges are extended angularly from an operative surface of said header to facilitate the spray adjustment by rotating said header.
12. The system as claimed in claim 1, wherein a cooler (160) is configured downstream of said second coater (150), said cooler (160) is in communication with said second coater (150) to receive said coated fertilizer to obtain a cooled coated fertilizer.
13. The system as claimed in claim 1, wherein a segregator (167) is configured downstream of said cooler, said segregator (167) is in communication with said cooler (160) to receive said cooled coated fertilizer to obtain fertilizer in the form of prills having a predetermined diameter.
14. The system as claimed in claim 13, wherein said predetermined diameter of said prills is in the range of 1 mm to 4 mm.
15. A process for coating a fertilizer, said process comprising the following steps:
a) pre-heating a fertilizer (174) to a temperature in the range of 50 °C to 60 °C to obtain a heated fertilizer;
b) separately heating a first coating agent to a temperature in the range of 130 °C to 145 °C to obtain a molten stream of first coating agent (170);
c) spray coating said heated fertilizer by using said molten stream of first coating agent (170) to obtain a first coated fertilizer;
d) separately heating a second coating agent (166) at a temperature in the range of 60 °C to 80 °C followed by spray coating over said first coated fertilizer to obtain a coated fertilizer; and
e) cooling said coated fertilizer and drying in air followed by segregating said dried coated fertilizer to obtain said coated fertilizer having predetermined diameter.
16. The process as claimed in claim 15, wherein said first coating agent (165) is selected from the group consisting of sulphur, a polymer, a mineral oil, beeswax, sodium oleate, shellac formulation, ethylene oxide, and higher fatty alcohols.
17. The process as claimed in claim 15, wherein said second coating agent (166) is selected from the group consisting of a polymer, a mineral oil, beeswax, sodium oleate, shellac formulation, ethylene oxide, and higher fatty alcohols .
18. The process as claimed in claim 16 and 17, wherein said polymer is selected from the group consisting of paraffin wax and microcrystalline wax.
19. The process as claimed in claim 15, wherein said coated fertilizer is sulphur coated urea fertilizer, characterized by having 37% Nitrogen and 17% sulphur and wherein said coated fertilizer is in the form of a prill having a diameter in the range of 2 mm to 3 mm.

Dated this 19th day of March, 2024

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
OF R. K. DEWAN & CO.
AUTHORIZED AGENT OF APPLICANT

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI