GB926781A - Dehydration of urea melts - Google Patents

Dehydration of urea melts

Info

Publication number
GB926781A
GB926781A GB1879259A GB1879259A GB926781A GB 926781 A GB926781 A GB 926781A GB 1879259 A GB1879259 A GB 1879259A GB 1879259 A GB1879259 A GB 1879259A GB 926781 A GB926781 A GB 926781A
Authority
GB
United Kingdom
Prior art keywords
melt
water
urea
evaporated
weight
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.)
Expired
Application number
GB1879259A
Inventor
Robert Nathan Summerville
Hugh Edward Templeton
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.)
Vulcan Cincinnati Inc
Original Assignee
Vulcan Cincinnati Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Vulcan Cincinnati Inc filed Critical Vulcan Cincinnati Inc
Priority to GB1879259A priority Critical patent/GB926781A/en
Priority to DEV16692A priority patent/DE1255099B/en
Publication of GB926781A publication Critical patent/GB926781A/en
Expired legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
    • C07D295/04—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms
    • C07D295/12—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly or doubly bound nitrogen atoms
    • C07D295/125—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly or doubly bound nitrogen atoms with the ring nitrogen atoms and the substituent nitrogen atoms attached to the same carbon chain, which is not interrupted by carbocyclic rings
    • C07D295/13—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly or doubly bound nitrogen atoms with the ring nitrogen atoms and the substituent nitrogen atoms attached to the same carbon chain, which is not interrupted by carbocyclic rings to an acyclic saturated chain
    • 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
    • C07C273/16—Separation; Purification

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

A urea melt containing about 10-30% by weight of water and having a temperature of about 200-290 DEG F. is dehydrated to a water content of not more than 1,5% by weight by evaporating the melt in such manner that the water vapour pressure over the urea melt is greater than the water vapour pressure which would be in equilibrium with the urea melt at its crystallization temperature, but not more than 20 mm. Hg greater when the water concentration in the melt is less than 10% by weight; biuret formation is thereby minimized and the formation of urea crystals during the evaporation avoided. Centrifugal thin-film evaporators, provided with heating jackets and rotating plates, are suitably used. In embodiments of the invention: (i) The urea melt is first evaporated at a pressure of 2,71-3,68 p.s.i.a. to provide a melt containing 4-6% of water and having a temperature of 245 DEG -260 DEG F., and the latter is then evaporated at less than 1,36 p.s.i.a. to provide a melt having \sO 1,5% water and at 270 DEG -285 DEG F. (ii) The first evaporation is at 2,71-3,68 p.s.i.a. to provide a melt containing 4-6% water at 245 DEG -260 DEG F., and the latter is evaporated at 4-19,7 p.s.i.a. while flowing countercurrent to a stream of inert gas to provide a melt containing \sO 1,5% of water at 270 DEG -285 DEG F. (iii) The melt is evaporated at 4-19,7 p.s.i.a. while flowing countercurrent to a stream of inert gas; the resulting melt is optionally dehydrated further at 5-13 mm. Hg to provide a melt containing \sO 0,20% water at 272 DEG -285 DEG F. A table is given showing the partial pressure of water over urea melts containing 4-30% by weight of water. The stream of inert gas is preferably preheated, e.g. to about 280 DEG F.ALSO:A urea melt containing about 10-30% by weight of water and having a temperature of about 200-290 DEG F. is dehydrated to a water content of not more than 1.5% by weight by evaporating the melt in such manner that the water vapour pressure over the urea melt is greater than the water vapour pressure which would be in equilibrium with the urea melt at its crystallisation temperature but not more than 20 mm. Hg greater when the water concentration in the melt is less than 10% by weight; biuret formation is thereby minimized and the formation of urea crystals during the evaporation avoided. The resulting urea melt may be flaked, pelletized, granulated, or formed into prills. In embodiments of the invention:-(i) The urea melt is first evaporated at a pressure of 2.71-3.68 psia to provide a melt containing 4-6% of water and having a temperature of 245-260 DEG F., and the latter is then evaporated at less than 1.36 psia to provide a melt having not greater than 1.5% water and at 270-285 DEG F. (ii) The first evaporation is at 2.71-3.68 psia to provide a melt containing 4-6% of water at 245-260 DEG F., and the latter evaporated at 4-19.7 psia while flowing countercurrent to a stream of inert gas to provide a melt containing not greater than 1.5% water at 270-285 DEG F. (iii) The melt is evaporated at 4-19.7 psia while flowing countercurrent to a stream of inert gas; the resulting melt is optionally dehydrated further at 5-13 mm. Hg to provide a melt containing not greater than 0.20% of water at 272-285 DEG F. A table is given showing the partial pressure of water in psia over urea melts of various water contents from 4 to 30% by weight. The stream of inert gas is preferably preheated, e.g. to about 280 DEG F.
GB1879259A 1959-06-02 1959-06-02 Dehydration of urea melts Expired GB926781A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB1879259A GB926781A (en) 1959-06-02 1959-06-02 Dehydration of urea melts
DEV16692A DE1255099B (en) 1959-06-02 1959-06-11 Process for dewatering a urea melt

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1879259A GB926781A (en) 1959-06-02 1959-06-02 Dehydration of urea melts

Publications (1)

Publication Number Publication Date
GB926781A true GB926781A (en) 1963-05-22

Family

ID=10118505

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1879259A Expired GB926781A (en) 1959-06-02 1959-06-02 Dehydration of urea melts

Country Status (1)

Country Link
GB (1) GB926781A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5273623A (en) * 1990-04-24 1993-12-28 Snamprogetti, S.P.A. Process for concentrating urea solution under vacuum
WO1997028100A1 (en) * 1996-02-01 1997-08-07 Toyo Engineering Corporation Process for preparing granular urea
WO2022106083A1 (en) * 2020-11-18 2022-05-27 Casale Sa Process for producing biuret from urea

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5273623A (en) * 1990-04-24 1993-12-28 Snamprogetti, S.P.A. Process for concentrating urea solution under vacuum
US5736003A (en) * 1990-04-24 1998-04-07 Snamprogetti S.P.A. Apparatus for concentrating urea solutions under vacuum
WO1997028100A1 (en) * 1996-02-01 1997-08-07 Toyo Engineering Corporation Process for preparing granular urea
WO2022106083A1 (en) * 2020-11-18 2022-05-27 Casale Sa Process for producing biuret from urea
US12030837B2 (en) 2020-11-18 2024-07-09 Casale Sa Process for producing biuret from urea

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