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US20180185803A1 - Method for producing solid urea by granulation - Google Patents

Method for producing solid urea by granulation Download PDF

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Publication number
US20180185803A1
US20180185803A1 US15/741,652 US201615741652A US2018185803A1 US 20180185803 A1 US20180185803 A1 US 20180185803A1 US 201615741652 A US201615741652 A US 201615741652A US 2018185803 A1 US2018185803 A1 US 2018185803A1
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US
United States
Prior art keywords
urea
granulation
section
formaldehyde
prilling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US15/741,652
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English (en)
Inventor
Gianfranco Bedetti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Casale SA
Original Assignee
Casale SA
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Filing date
Publication date
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Assigned to CASALE SA reassignment CASALE SA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BEDETTI, GIANFRANCO
Publication of US20180185803A1 publication Critical patent/US20180185803A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/16—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by suspending the powder material in a gas, e.g. in fluidised beds or as a falling curtain
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05C—NITROGENOUS FERTILISERS
    • C05C9/00—Fertilisers containing urea or urea compounds
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05C—NITROGENOUS FERTILISERS
    • C05C9/00—Fertilisers containing urea or urea compounds
    • C05C9/005—Post-treatment
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C273/00—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
    • C07C273/02—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of urea, its salts, complexes or addition compounds
    • C07C273/14—Separation; Purification; Stabilisation; Use of additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C273/00—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
    • C07C273/02—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of urea, its salts, complexes or addition compounds
    • C07C273/14—Separation; Purification; Stabilisation; Use of additives
    • C07C273/16—Separation; Purification

Definitions

  • the invention relates to the field of the production of solid urea.
  • Solid urea is produced mainly by prilling or granulation.
  • Prilling involves cooling droplets of liquid urea falling inside a tower by means of counter-flowing air.
  • the solids thus formed are termed prills.
  • Granulation involves spraying liquid urea onto granules inside a proper granulator, for example in a fluid bed; the liquid forms a layer which solidifies, thus increasing the size of the granule. Both techniques are known to persons skilled in the art and are described in the literature, for example in Meessen, “Urea”, Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag, 2010.
  • Granulation offers a series of recognized advantages and is considered to be superior to prilling. It is well-known that the prills have a certain fragility essentially due to the rapid cooling of the droplets which creates a porous structure. The solid product obtained by granulation has a much greater mechanical strength, in particular against crushing and knocks, and is therefore more suitable for storage and transportation in bulk form. Another advantage of granulation is the capacity to produce granules of a larger size, for example with a diameter of 3 mm or more, while the diameter of prills is no more than 2 mm because larger dimensions would require a too large and expensive prilling tower and would originate problems of instability of the droplets.
  • a prilling process requires a urea melt with a high concentration, preferably with a concentration of 99.7% by weight or more.
  • the urea plants produce (downstream of the recovery section) a solution containing a certain quantity of water (typically about 30%); hence the aforesaid concentration is reached using a suitable concentration and evaporation section designed to completely remove the water.
  • a granulation process instead, according to the teaching of the prior art, is carried out with a solution of urea having a concentration of 96% or up to a maximum of 98% by weight, i.e. still containing about 2-4% of water.
  • the granulation process is regarded as being able to tolerate a greater water content than prilling and therefore the prior art does not consider it necessary to entirely remove the water.
  • a water content of around 4% is considered advantageous in the granulation process to avoid the formation of biuret which is an undesirable by-product.
  • a first drawback is the cost: plants which produce thousands of tons of urea per day require a large quantity of formaldehyde, of the order of several tons per day, which must be provided. Formaldehyde is not always produced on site and many urea plants are located in remote areas. Providing this additive therefore gives rise to a high purchase, transportation and storage cost.
  • Solid urea (prills or granules) is mainly used in agriculture as fertilizer, which means that the formaldehyde contained in the urea is released into the ground. This creates a negative impact on the environment and problems for the human health, since formaldehyde is considered a possible carcinogen agent. But nevertheless, it is considered to be indispensable.
  • technical urea There are procedures for producing urea without formaldehyde which, however, are costly and produce small amounts.
  • the idea forming the basis of the invention is to use a pure urea melt in a granulation process, without the addition of formaldehyde.
  • said urea melt has a purity of more than 98% by weight, more advantageously of at least 99.5% and even more advantageously of at least 99.7%.
  • Granulation is essentially a layer-by-layer growth process and the applicant has noted that evaporation of the water (which occurs during granulation) tends to generate porosity within the core of the granule. Therefore, although the surface, i.e. the outer layer, appears to have good visual and mechanical properties, the internal layers of the granule are weakened by the porosity.
  • the invention requires to remove water in a more efficient way compared to conventional granulation technology, and this may result in an—albeit limited—additional cost. This cost is however offset by the superior quality of the end product and in particular by the huge advantage represented by the elimination of added formaldehyde.
  • the superior quality of the product arises from the improved granule structure.
  • the invention allows obtain a more uniform granule structure owing to the elimination of the water evaporation generating porosity in the internal layers of the granule.
  • the invention provides a technique for obtaining solid urea in granule form which is free from formaldehyde.
  • the invention therefore enables urea producers to provide a product which has a mechanical strength equivalent to or superior to the granules which are nowadays available, but has the advantage of containing no formaldehyde and of being regarded as an environmentally friendly product.
  • Formaldehyde-free urea is thus available at lower costs compared to the known processes for the production of technical urea.
  • An aspect of the invention is also a method for revamping existing plants with a prilling section.
  • These plants already have an evaporation section designed to reach a high concentration (e.g. 99.7%) for correct feeding of the prilling tower, and therefore may be revamped by adding a granulation section and feeding at least part of the high-concentration urea melt, which is provided by the existing evaporation section, to the new granulation section.
  • the plant provides an improved product (granules instead of prills), the addition of formaldehyde can be eliminated and the already present evaporation section is exploited.
  • the invention also responds to the need of revamping and improving the prilling tower-based urea plants, which are often outdated, but are still present in large numbers all over the world.
  • a part of the urea melt can be used in a prilling tower to produce seeds for the granulation process.
  • This process is advantageous particularly when the invention is applied to the revamping of a urea plant comprising a prilling tower, since the existing prilling tower can be used for said purpose.
  • the production of prills can be discontinued, which means that the output of the revamped plant is solely of granules.
  • the invention can be implemented using all the granulation techniques known per se.
  • fluid-bed granulation can be used.
  • fluid-bed granulation inside a longitudinal granulator may be used, where the fluidized granules rotate to form a vortex or two counter-rotating vortices, as explained for example in EP 1412069.
  • Part of the urea melt feed may be suitably used to produce the seeds of the granulation process.
  • FIG. 1 is a scheme of a first embodiment of the invention.
  • FIG. 2 is a scheme of a second embodiment.
  • FIG. 3 is a scheme of a third embodiment.
  • FIG. 1 shows a schematic urea plant comprising a synthesis section US and a recycling section UR.
  • the recycling section UR provides an aqueous solution of urea SOL containing about 70% by weight of urea.
  • Said solution passes through evaporation section EV inside which the water is removed, obtaining a urea melt UM containing more than 98%, for example 99.7%, by weight of urea.
  • Said urea melt UM without the addition of formaldehyde, is fed to a granulation section GS, obtaining granules of urea U.
  • FIG. 2 shows an example of revamping of a plant in which the urea melt UM is originally fed to a prilling section PS which produces urea prills P. At least a part UM′ of said urea melt UM is fed to a granulation section GS which is arranged parallel to the prilling section PS, also in this case without the addition of formaldehyde.
  • the UM stream is directed entirely towards the new granulation section GS, i.e. the production of prills P is discontinued.
  • FIG. 3 illustrates an embodiment which is a variant of FIG. 2 , wherein a portion UM′′ of the urea melt is used in the existing prilling section PS to produce solid seeds S for the granulation section GS.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Fertilizers (AREA)
US15/741,652 2015-07-03 2016-06-08 Method for producing solid urea by granulation Abandoned US20180185803A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP15175347.2 2015-07-03
EP15175347.2A EP3112332A1 (en) 2015-07-03 2015-07-03 Method for producing solid urea by granulation
PCT/EP2016/063027 WO2017005446A1 (en) 2015-07-03 2016-06-08 Method for producing solid urea by granulation

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2016/063027 A-371-Of-International WO2017005446A1 (en) 2015-07-03 2016-06-08 Method for producing solid urea by granulation

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US16/819,867 Continuation US20200215507A1 (en) 2015-07-03 2020-03-16 Method for producing solid urea by granulation

Publications (1)

Publication Number Publication Date
US20180185803A1 true US20180185803A1 (en) 2018-07-05

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ID=53886822

Family Applications (3)

Application Number Title Priority Date Filing Date
US15/741,652 Abandoned US20180185803A1 (en) 2015-07-03 2016-06-08 Method for producing solid urea by granulation
US16/819,867 Abandoned US20200215507A1 (en) 2015-07-03 2020-03-16 Method for producing solid urea by granulation
US17/526,759 Active US12403436B2 (en) 2015-07-03 2021-11-15 Method for producing solid urea by granulation

Family Applications After (2)

Application Number Title Priority Date Filing Date
US16/819,867 Abandoned US20200215507A1 (en) 2015-07-03 2020-03-16 Method for producing solid urea by granulation
US17/526,759 Active US12403436B2 (en) 2015-07-03 2021-11-15 Method for producing solid urea by granulation

Country Status (10)

Country Link
US (3) US20180185803A1 (ru)
EP (2) EP3112332A1 (ru)
CN (1) CN107912024A (ru)
AU (3) AU2016289338A1 (ru)
BR (1) BR112018000110A2 (ru)
CL (1) CL2017003383A1 (ru)
MX (1) MX2017016873A (ru)
RU (1) RU2742933C2 (ru)
UA (1) UA124298C2 (ru)
WO (1) WO2017005446A1 (ru)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102021108187A1 (de) 2021-03-31 2022-10-06 Skw Stickstoffwerke Piesteritz Gmbh Granuliertes pH-neutrales Harnstoff-Ammoniumsulfat-Düngemittel mit Ureaseinhibitor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3398191A (en) * 1963-12-09 1968-08-20 Cominco Ltd Process for the production of granular nitrogenous compounds
US20060177574A1 (en) * 2003-07-17 2006-08-10 Mutsers Stanislaus M P Process for the preparation of urea granules
US20110064635A1 (en) * 2008-05-14 2011-03-17 Paul Niehues Method for reducing aerosol emissions in a urea granulation plant
WO2013189625A1 (en) * 2012-06-18 2013-12-27 Urea Casale Sa Method and apparatus for the granulation of a liquid, in particular for the granulation of urea

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2933526A (en) * 1956-02-25 1960-04-19 Lonza Electric & Chem Works Process for the manufacture of urea in granular form
US4525198A (en) * 1981-05-13 1985-06-25 Compagnie Neerlandaise De L'azote Process for the production of urea granules
NL184769C (nl) 1981-07-03 1989-11-01 Azote Sa Cie Neerlandaise Werkwijze voor het vervaardigen van ureumkorrels.
US4842790A (en) * 1988-02-22 1989-06-27 Tennessee Valley Authority Method and apparatus for producing high-strength grannular particulates from low-strength prills
RO111362B1 (ro) * 1995-08-24 1996-09-30 Sc Azomures Sa Procedeu de obținere a ureei granulate
DE60216597T2 (de) * 2001-03-21 2007-10-04 Urea Casale S.A. Wirbelschichtgranulation
EP1670735B1 (en) 2003-10-06 2012-08-01 YARA International ASA Method of improving the crushing strength, impact resistance and compressibility of urea.
AU2004291238B2 (en) * 2003-11-10 2009-09-17 Stamicarbon B.V. Process for the preparation of urea granules
RU2281270C1 (ru) * 2004-12-31 2006-08-10 Открытое Акционерное Общество "Научно-Исследовательский И Проектный Институт Карбамида И Продуктов Органического Синтеза" (Оао Ниик) Способ получения гранулированного карбамида и грануляционная башня
JP4852270B2 (ja) 2005-07-13 2012-01-11 東洋エンジニアリング株式会社 顆粒尿素製品の製造方法
CN100586906C (zh) 2007-09-20 2010-02-03 兖矿鲁南化肥厂 高塔滚筒复合肥生产工艺
CN103827081B (zh) * 2011-08-17 2016-06-01 斯塔米卡邦有限公司 最后的浓缩器与造粒塔之间的熔融尿素输送时间短的尿素制备方法
CN203303902U (zh) * 2013-06-24 2013-11-27 湖南宜化化工有限责任公司 一种尿素造粒喷头
DE102014108703A1 (de) * 2014-06-20 2015-12-24 Thyssenkrupp Ag Harnstoffzusammensetzung und Verfahren zu ihrer Herstellung
CN104402769A (zh) * 2014-12-04 2015-03-11 重庆建峰化工股份有限公司 一种车用尿素的生产工艺
EP3594194A1 (en) * 2018-07-12 2020-01-15 Casale Sa Urea granulation process
EP4320095B1 (en) * 2021-04-07 2025-01-22 Casale Sa Urea production process and plant

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3398191A (en) * 1963-12-09 1968-08-20 Cominco Ltd Process for the production of granular nitrogenous compounds
US20060177574A1 (en) * 2003-07-17 2006-08-10 Mutsers Stanislaus M P Process for the preparation of urea granules
US20110064635A1 (en) * 2008-05-14 2011-03-17 Paul Niehues Method for reducing aerosol emissions in a urea granulation plant
WO2013189625A1 (en) * 2012-06-18 2013-12-27 Urea Casale Sa Method and apparatus for the granulation of a liquid, in particular for the granulation of urea
US9403733B2 (en) * 2012-06-18 2016-08-02 Casale Sa Method for the granulation of urea

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
EPA "8.2 Urea" Emission Factors, 1995, p. 1-6, downloaded from https://www3.epa.gov/ttn/chief/old/ap42/ch08/s02/final/c08s02_jan1995.pdf on 9/10/2019) (Year: 1995) *

Also Published As

Publication number Publication date
AU2023200551B2 (en) 2025-01-30
AU2020267178A1 (en) 2020-12-03
US12403436B2 (en) 2025-09-02
WO2017005446A1 (en) 2017-01-12
US20220072492A1 (en) 2022-03-10
CA2988830A1 (en) 2017-01-12
RU2018104089A (ru) 2019-08-06
EP3317234B1 (en) 2024-10-30
RU2018104089A3 (ru) 2019-09-10
EP3112332A1 (en) 2017-01-04
BR112018000110A2 (pt) 2018-09-04
CL2017003383A1 (es) 2018-06-01
CN107912024A (zh) 2018-04-13
MX2017016873A (es) 2018-04-30
US20200215507A1 (en) 2020-07-09
RU2742933C2 (ru) 2021-02-11
EP3317234A1 (en) 2018-05-09
AU2023200551A1 (en) 2023-03-02
AU2016289338A1 (en) 2018-01-18
UA124298C2 (uk) 2021-08-25

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