Indian Patents. 255367:UREA GRANULATION PROCESS

Title of Invention	UREA GRANULATION PROCESS
Abstract	Urea granulation process in a granulator that contains urea nuclei, to which a un melt and at least one granulation additive are added, wherein the urea nuclei a transported and the urea melt is added perpendicularly to the direction of transport of the urea nuclei, wherein the granulation additive is at least partially supplied the last section of the granulator.

Full Text	UREA GRANULATION PROCESS The invention relates to a urea granulation process in a granulator that contains urea nuclei, to which a urea melt and at least one granulation additive are added, wherein the urea nuclei are transported and the urea melt is added perpendicularly to the direction of transport of the urea nuclei. Such urea granulation processes are described in the Encyclopedia of Chemical Technology, third edition, volume 23, pages 566-572. It discusses among other things the Cominco granulation process, the TVA falling-curtain granulation process, the NSM granulation process and the MitsuiToatsu-Toyo Engineering granulation process, wherein granulation is effected in the manner described above. The Cominco granulation process and the TVA falling-curtain granulation process employ as a granulator a drum that rotates about its longitudinal axis and so transports nuclei that are supplied at the beginning of the granulator through the granulator, with sprayers being present over a large part of the length of the drum for spraying urea melt. In the NSM granulation process and the MitsuiToatsu-Toyo Engineering granulation process the nuclei are introduced in a fluid bed and transported in the fluid bed, with the nuclei growing to form granules on account of urea melt being sprayed in the fluid bed by sprayers that are positioned along a large part of the length of the fluid bed. It is known that in these granulation processes formaldehyde or another granulation additive may be added to the urea melt before it is supplied to the granulator so as to improve granulation and to enhance the properties of the urea granules. A drawback of the known process is that comparatively much granulation additive relative to the urea melt needs to be added in order to achieve the desired improvements. The object of the invention is to reduce the quantity of granulation additive relative to the urea melt, with urea granulate with comparable properties being obtained. The invention is characterized in that the granulation additive is at least partially supplied to the last section of the granulator. In this way, less granulation additive is needed for obtaining urea granulate with good properties. This is advantageous since granulation additives are costly and their addition heavily affects the cost price of urea granulate. A granulator for granulating urea comprises a casing to one side of which nuclei are supplied. Furthermore, the granuiator comprises means of transporting the granules that develop from the nuclei to the opposite side. In a drum granuiator such transport takes place through rotation of the drum granuiator and displacement of the granules by the blades present therein. In a fluid bed granuiator the fluid bed is located above a distribution plate. The fluid bed is maintained by the fluidization air supplied through the distribution plate. In a fluid bed granuiator the transport of granules through the granuiator is controlled by the supply direction of the fluidization air through the distribution plate. The urea melt is supplied to the granuiator perpendicularly to the transport direction of the nuclei and the urea granulate through the granuiator. Perpendicular here and hereinafter means at an angle of 70-110° to the transport direction of the nuclei and the urea granulate. The urea melt is supplied to the granuiator through sprayers or distributors that are located over almost the full length of the granuiator. According to the process of the invention the granulation additive is now at least partially supplied to the last section of the granuiator, that is, the section where the last sprayers or urea melt distributors are present. Besides the supply of the granulation additive to the last section of the granuiator, a portion of the granulation additive may be supplied in a preceding section of the granuiator by for example mixing a proportion of the granulation additive with the urea melt before it is added to the granuiator. Addition of the granulation additive at least partially to the last granuiator section means that at least 50% of the granulation additive is added here. Preferably at least 70% of the granulation additive is supplied to the last granuiator section. The granulation additive may be supplied separately from the urea melt but is preferably mixed with the urea melt before it is supplied to the last granuiator section. Following the last granuiator section, prior to the granulate leaving the granuiator, the granuiator typically contains a zone to which urea melt is not supplied. The granulate is cooled in this zone. Examples of granulation additives are formaldehyde, methylolurea, formurea, hexamethylene tetramine. Formaldehyde is preferably used as granulation additive for improving the mechanical strength of the urea granules and for reducing the tendency of the urea granules to adhere together during storage (caking behaviour). Formaldehyde may be added as gaseous formaldehyde, formalin, paraformaldehyde, a solution of paraformaldehyde or as urea formaldehyde precondensate. Formaldehyde is most often added as formaldehyde precondensate. Formaldehyde precondensate contains for example 60 wt.% formaldehyde. Preferably 0.01-0.4 wt.% formaldehyde is added to the urea melt relative to the urea added. The invention also relates to a urea granule containing a granulation additive. In the processes described in the aforementioned Encyclopedia of Chemical Technology, third edition, volume 23, pages 566-572, the granulation additive is added over the full length of the granulator, as a result of which the concentration of the granulation additive is the same throughout the urea granule. State of the art processes are known whereby the granulation additive is distributed over the surface of the urea granule after the formation of a urea granule, so in essence after the granulation process is completed. Thus, following such a process the granulation additive is present on the urea granule's surface only. The process according to the invention ensures that the granulation additive is present in the granule such that the concentration of the granulation additive is highest in the outer layer of the granule. The granulation additive is not only present on the surface of the granule, but is solidified together with the urea melt in the outer layer of the granule. Granulation additive may also be present in the rest of the granule. Preferably, the granulation additive is present in the granule such that its concentration increases from the core to the outside surface of the granule. The granules according to the invention preferably contain 0,01-0,4 wt.% formaldehyde relative to urea. In Figure 1 urea granulation process according to the invention is represented. Figure 1 shows a granulator wherein sprayers (S) are present over almost the full length for adding the urea melt originating from a urea plant or a urea melt storage tank (U). Nuclei (N) are supplied to the granulator above a distribution plate. Fluidization air and secondary air (A) are supplied beneath the distribution plate and to the sprayers, respectively. At the end of the granulator the granules (G) are discharged. The granulation additive (D) is completely added to the urea melt supply line connecting to the last sprayer. Comparative Experiment A In a urea granulation process according to figure 1 a formaldehyde-containing solution (UFC 85®) was added to the urea melt directly after the evaporators in the urea plant (U). The amount of the formaldehyde-containing solution added, was such that the urea granules obtained after granulation, contained 0.4 wt% of formaldehyde relative to urea. Urea granules were obtained wherein formaldehyde was evenly distributed. The crushing strength of the granule was determined using an apparatus of Lloyds instruments; type LRX+ and has a value of 4.8 kgf determined on a granule with a diameter of 2.85 mm. Almost no dust formation occurred during transport and handling of the granules. Example I In a urea granulation process according to figure 1 a formaldehyde-containing solution (UFC 85®) was partially added to the urea melt directly after the evaporators in the urea plant (U) and partially to the urea melt at place D according to the figure. The ratio of the amount of the formaldehyde-containing solution added directly after the evaporators and the amount added to place D was 1:2.5. The total amount of the formaldehyde-containing solution that was added was such that the urea granules obtained after granulation, contained 0.2 wt% of formaldehyde relative to urea. Urea granules were obtained wherein the concentration of formaldehyde in the outer layer of the granule was about 30% higher than the concentration in the middle of the granule. The crushing strength of the granule was determined as described for Comparative Experiment A and had a value of 4.8 kgf. Almost no dust formation occurred during transport and handling. With respect to dust formation the product was comparable with the product according to Comparative Experiment A. CLAIMS 1. Urea granulation process in a granulator that contains urea nuclei, to which a urea melt and at least one granulation additive are added, wherein the urea nuclei are transported and the urea melt is added perpendicularly to the direction of transport of the urea nuclei characterized in that the granulation additive is at least partially supplied to the last section of the granulator. 2. Process according to Claim 1, characterized in that at least 70 wt.% of the granulation additive is supplied to the last granulator section. 3. Process according to Claim 1 or 2, characterized in that the granulation additive is mixed with the urea melt before it is supplied to the last granulator section. 4. Process according to any one of Claims 1-3, characterized in that the granulation additive is formaldehyde. 5. Process according to any one of Claims 1-4, characterized in that 0.01-0.4 wt.% formaldehyde is added to the urea melt relative to urea. 6. Urea granule containing a granulation additive, characterized in that the concentration of the granulation additive is highest in the outer layer of the granule. 7. Urea granule according to Claim 6, characterized in that the granulation additive is present in the whole granule such that the concentration of the granulation additive increases from the core to the outside surface. 8. Urea granule according to Claim 6 or 7, characterized in that the granulation additive is formaldehyde. 9. Urea granule according to any one of claims 6-8, characterized in that the granule contains 0,01-0,4 wt.% formaldehyde relative to urea.

Full Text

UREA GRANULATION PROCESS
The invention relates to a urea granulation process in a granulator that contains urea nuclei, to which a urea melt and at least one granulation additive are added, wherein the urea nuclei are transported and the urea melt is added perpendicularly to the direction of transport of the urea nuclei.
Such urea granulation processes are described in the Encyclopedia of Chemical Technology, third edition, volume 23, pages 566-572. It discusses among other things the Cominco granulation process, the TVA falling-curtain granulation process, the NSM granulation process and the MitsuiToatsu-Toyo Engineering granulation process, wherein granulation is effected in the manner described above.
The Cominco granulation process and the TVA falling-curtain granulation process employ as a granulator a drum that rotates about its longitudinal axis and so transports nuclei that are supplied at the beginning of the granulator through the granulator, with sprayers being present over a large part of the length of the drum for spraying urea melt. In the NSM granulation process and the MitsuiToatsu-Toyo Engineering granulation process the nuclei are introduced in a fluid bed and transported in the fluid bed, with the nuclei growing to form granules on account of urea melt being sprayed in the fluid bed by sprayers that are positioned along a large part of the length of the fluid bed.
It is known that in these granulation processes formaldehyde or another granulation additive may be added to the urea melt before it is supplied to the granulator so as to improve granulation and to enhance the properties of the urea granules.
A drawback of the known process is that comparatively much granulation additive relative to the urea melt needs to be added in order to achieve the desired improvements.
The object of the invention is to reduce the quantity of granulation additive relative to the urea melt, with urea granulate with comparable properties being obtained.
The invention is characterized in that the granulation additive is at least partially supplied to the last section of the granulator. In this way, less granulation additive is needed for obtaining urea granulate with good properties.

This is advantageous since granulation additives are costly and their addition heavily affects the cost price of urea granulate.
A granulator for granulating urea comprises a casing to one side of which nuclei are supplied. Furthermore, the granuiator comprises means of transporting the granules that develop from the nuclei to the opposite side. In a drum granuiator such transport takes place through rotation of the drum granuiator and displacement of the granules by the blades present therein.
In a fluid bed granuiator the fluid bed is located above a distribution plate. The fluid bed is maintained by the fluidization air supplied through the distribution plate. In a fluid bed granuiator the transport of granules through the granuiator is controlled by the supply direction of the fluidization air through the distribution plate.
The urea melt is supplied to the granuiator perpendicularly to the transport direction of the nuclei and the urea granulate through the granuiator. Perpendicular here and hereinafter means at an angle of 70-110° to the transport direction of the nuclei and the urea granulate.
The urea melt is supplied to the granuiator through sprayers or distributors that are located over almost the full length of the granuiator. According to the process of the invention the granulation additive is now at least partially supplied to the last section of the granuiator, that is, the section where the last sprayers or urea melt distributors are present.
Besides the supply of the granulation additive to the last section of the granuiator, a portion of the granulation additive may be supplied in a preceding section of the granuiator by for example mixing a proportion of the granulation additive with the urea melt before it is added to the granuiator. Addition of the granulation additive at least partially to the last granuiator section means that at least 50% of the granulation additive is added here. Preferably at least 70% of the granulation additive is supplied to the last granuiator section.
The granulation additive may be supplied separately from the urea melt but is preferably mixed with the urea melt before it is supplied to the last granuiator section.
Following the last granuiator section, prior to the granulate leaving the granuiator, the granuiator typically contains a zone to which urea melt is not supplied. The granulate is cooled in this zone.
Examples of granulation additives are formaldehyde, methylolurea, formurea, hexamethylene tetramine. Formaldehyde is preferably used as granulation

additive for improving the mechanical strength of the urea granules and for reducing the tendency of the urea granules to adhere together during storage (caking behaviour). Formaldehyde may be added as gaseous formaldehyde, formalin, paraformaldehyde, a solution of paraformaldehyde or as urea formaldehyde precondensate.
Formaldehyde is most often added as formaldehyde precondensate. Formaldehyde precondensate contains for example 60 wt.% formaldehyde. Preferably 0.01-0.4 wt.% formaldehyde is added to the urea melt relative to the urea added.
The invention also relates to a urea granule containing a granulation additive.
In the processes described in the aforementioned Encyclopedia of Chemical Technology, third edition, volume 23, pages 566-572, the granulation additive is added over the full length of the granulator, as a result of which the concentration of the granulation additive is the same throughout the urea granule. State of the art processes are known whereby the granulation additive is distributed over the surface of the urea granule after the formation of a urea granule, so in essence after the granulation process is completed. Thus, following such a process the granulation additive is present on the urea granule's surface only.
The process according to the invention ensures that the granulation additive is present in the granule such that the concentration of the granulation additive is highest in the outer layer of the granule. The granulation additive is not only present on the surface of the granule, but is solidified together with the urea melt in the outer layer of the granule. Granulation additive may also be present in the rest of the granule.
Preferably, the granulation additive is present in the granule such that its concentration increases from the core to the outside surface of the granule.
The granules according to the invention preferably contain 0,01-0,4 wt.% formaldehyde relative to urea.
In Figure 1 urea granulation process according to the invention is represented. Figure 1 shows a granulator wherein sprayers (S) are present over almost the full length for adding the urea melt originating from a urea plant or a urea melt storage tank (U). Nuclei (N) are supplied to the granulator above a distribution plate. Fluidization air and secondary air (A) are supplied beneath the distribution plate and to the sprayers, respectively.
At the end of the granulator the granules (G) are discharged. The granulation additive (D) is completely added to the urea melt supply line connecting to the last sprayer.

Comparative Experiment A
In a urea granulation process according to figure 1 a formaldehyde-containing solution
(UFC 85®) was added to the urea melt directly after the evaporators in the urea plant
(U). The amount of the formaldehyde-containing solution added, was such that the
urea granules obtained after granulation, contained 0.4 wt% of formaldehyde relative to
urea. Urea granules were obtained wherein formaldehyde was evenly distributed.
The crushing strength of the granule was determined using an apparatus of Lloyds
instruments; type LRX+ and has a value of 4.8 kgf determined on a granule with a
diameter of 2.85 mm.
Almost no dust formation occurred during transport and handling of the granules.
Example I
In a urea granulation process according to figure 1 a formaldehyde-containing solution
(UFC 85®) was partially added to the urea melt directly after the evaporators in the urea
plant (U) and partially to the urea melt at place D according to the figure. The ratio of
the amount of the formaldehyde-containing solution added directly after the
evaporators and the amount added to place D was 1:2.5. The total amount of the
formaldehyde-containing solution that was added was such that the urea granules
obtained after granulation, contained 0.2 wt% of formaldehyde relative to urea.
Urea granules were obtained wherein the concentration of formaldehyde in the outer
layer of the granule was about 30% higher than the concentration in the middle of the
granule.
The crushing strength of the granule was determined as described for Comparative
Experiment A and had a value of 4.8 kgf.
Almost no dust formation occurred during transport and handling. With respect to dust
formation the product was comparable with the product according to Comparative
Experiment A.

CLAIMS
1. Urea granulation process in a granulator that contains urea nuclei, to which a
urea melt and at least one granulation additive are added, wherein the urea
nuclei are transported and the urea melt is added perpendicularly to the
direction of transport of the urea nuclei characterized in that the granulation
additive is at least partially supplied to the last section of the granulator.
2. Process according to Claim 1, characterized in that at least 70 wt.% of the
granulation additive is supplied to the last granulator section.
3. Process according to Claim 1 or 2, characterized in that the granulation
additive is mixed with the urea melt before it is supplied to the last granulator
section.
4. Process according to any one of Claims 1-3, characterized in that the
granulation additive is formaldehyde.
5. Process according to any one of Claims 1-4, characterized in that 0.01-0.4
wt.% formaldehyde is added to the urea melt relative to urea.
6. Urea granule containing a granulation additive, characterized in that the
concentration of the granulation additive is highest in the outer layer of the
granule.
7. Urea granule according to Claim 6, characterized in that the granulation
additive is present in the whole granule such that the concentration of the
granulation additive increases from the core to the outside surface.
8. Urea granule according to Claim 6 or 7, characterized in that the granulation
additive is formaldehyde.
9. Urea granule according to any one of claims 6-8, characterized in that the
granule contains 0,01-0,4 wt.% formaldehyde relative to urea.

Documents:

4284-delnp-2006-1-Correspondence Others-(20-04-2012).pdf

4284-delnp-2006-1-Form-3-(20-04-2012).pdf

4284-delnp-2006-1-Petition-137-(20-04-2012).pdf

4284-delnp-2006-abstract.pdf

4284-DELNP-2006-Assignment-(08-11-2010).pdf

4284-delnp-2006-Claims-(01-10-2012).pdf

4284-delnp-2006-claims.pdf

4284-delnp-2006-Correspondence Others-(20-04-2012).pdf

4284-DELNP-2006-Correspondence Others-(28-06-2012).pdf

4284-delnp-2006-correspondence others.pdf

4284-delnp-2006-Correspondence-Others-(01-10-2012).pdf

4284-DELNP-2006-Correspondence-Others-(08-11-2010).pdf

4284-delnp-2006-description (complete).pdf

4284-delnp-2006-Drawings-(01-10-2012).pdf

4284-delnp-2006-drawings.pdf

4284-delnp-2006-form-1.pdf

4284-delnp-2006-form-2.pdf

4284-DELNP-2006-Form-3-(28-06-2012).pdf

4284-delnp-2006-form-3.pdf

4284-delnp-2006-form-5.pdf

4284-DELNP-2006-GPA-(08-11-2010).pdf

4284-delnp-2006-GPA-(20-04-2012).pdf

4284-delnp-2006-gpa.pdf

4284-delnp-2006-pct-210.pdf

4284-delnp-2006-pct-304.pdf

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Patent Number

255367

Indian Patent Application Number

4284/DELNP/2006

PG Journal Number

08/2013

Publication Date

22-Feb-2013

Grant Date

15-Feb-2013

Date of Filing

25-Jul-2006

Name of Patentee

STAMICARBON B.V.

Applicant Address

HET OVERLOON, 1, NL-6411 TE HEERLEN, THE NETHERLANDS.

Inventors:

#	Inventor's Name	Inventor's Address
1	MEESSEN JOZEF HUBERT	MARCHIERSTRAAT 10, NL-6321 AL WIJLRE, THE NETHERLANDS.

PCT International Classification Number

B01J 2/02

PCT International Application Number

PCT/NL2005/000136

PCT International Filing date

2005-02-24

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	1025805	2004-03-25	Netherlands