WO2010063584A1 - Procédé de génération d'un produit sulfate d'ammonium à gros grains - Google Patents

Procédé de génération d'un produit sulfate d'ammonium à gros grains Download PDF

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Publication number
WO2010063584A1
WO2010063584A1 PCT/EP2009/065454 EP2009065454W WO2010063584A1 WO 2010063584 A1 WO2010063584 A1 WO 2010063584A1 EP 2009065454 W EP2009065454 W EP 2009065454W WO 2010063584 A1 WO2010063584 A1 WO 2010063584A1
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WO
WIPO (PCT)
Prior art keywords
suspension
solution
crystallization stage
ammonium sulfate
crystallization
Prior art date
Application number
PCT/EP2009/065454
Other languages
German (de)
English (en)
Inventor
Reinhard Scholz
Günter Hofmann
Johannes Widua
Original Assignee
Gea Messo Gmbh
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 Gea Messo Gmbh filed Critical Gea Messo Gmbh
Publication of WO2010063584A1 publication Critical patent/WO2010063584A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/24—Sulfates of ammonium
    • C01C1/248—Preventing coalescing or controlling form or size of the crystals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D9/00—Crystallisation
    • B01D9/0018—Evaporation of components of the mixture to be separated
    • B01D9/0031—Evaporation of components of the mixture to be separated by heating
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/24—Sulfates of ammonium
    • C01C1/242—Preparation from ammonia and sulfuric acid or sulfur trioxide
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05C—NITROGENOUS FERTILISERS
    • C05C3/00—Fertilisers containing other salts of ammonia or ammonia itself, e.g. gas liquor
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05C—NITROGENOUS FERTILISERS
    • C05C3/00—Fertilisers containing other salts of ammonia or ammonia itself, e.g. gas liquor
    • C05C3/005—Post-treatment

Definitions

  • the invention relates to a method for the continuous production of a coarse-grained crystalline ammonium sulfate product according to the preamble of patent claim 1.
  • Ammonium sulphate (NhU) 2 SO 4 ) is a large scale product used primarily as a fertilizer in agriculture for the supply of nitrogen and sulfur. In industrial terms, ammonium sulfate is by-produced in some chemical processes, particularly in the production of caprolactam. To meet the fertilizer requirements, the ammonium sulphate must be available as a coarse-grained product (RRSB) in the range of 1 to 4 mm). This is important in order to ensure a good throwing power and, in the case of mixing with other fertilizers, to suppress the tendency for segregation, which would be intensified by fines in a grain mixture.
  • RTSB coarse-grained product
  • coarse-grained crystallizates can be prepared from solutions in crystallizers of the type DTB (Draft Tube Baffled) or of the Oslo type.
  • DTB Double Tube Baffled
  • the problem arises that the average grain size of the product crystals produced in the crystallizer is subject to periodic fluctuations, i.
  • Phases with a high coarse grain fraction alternate with phases in which predominantly fine-grained crystals (for example, grain size less than 1 mm) are obtained. This is the result of a strong spontaneous primary nucleation with increased supersaturation in the crystallizer.
  • all nuclei formed are dissolved by the strong fine crystal dissolution due to the temperature increase in the heat exchanger of the external circuit of a DTB crystallizer or in the circulation of an Oslo crystallizer.
  • EP 0632738 B1 discloses a continuous crystallization process in which a coarse-grained ammonium sulfate crystallizate can be prepared from a supersaturated aqueous ammonium sulfate solution in a DTB crystallizer.
  • a suspension of supersaturated ammonium sulfate solution and already formed crystals within the DTB crystallizer in an internal Circulation constantly circulated.
  • Evaporation of the solvent (water) constantly creates new supersaturation, which is degraded again as a result of the crystallization taking place. The vapors produced during evaporation are removed at the head of the DTB crystal transistor.
  • the external circuit before the heat exchanger and the feed line opens can be fed by the new concentrated ammonium sulfate solution in the crystallizer. From the bottom area, a partial stream of suspension with the proportion of solid contained in the desired particle size of the product crystallizate is continuously withdrawn. The product crystals are separated from the mother liquor in a thickener and then centrifuged, and the mother liquor is returned to the DTB crystallizer.
  • the temperature of the fed suspension must not exceed the operating temperature in the crystallizer.
  • the suspension must contain 6 to 24% by volume of crystallizate, with at least 35% of the crystals being greater than 1.2 mm, and the feed of the suspension should be such that the weight of the crystals in the feed suspension is in the range of 4 - 25% of the weight of the crystals in the withdrawn from the bottom of the crystallizer suspension with the product crystals.
  • This targeted feeding of crystal suspension in a crystallizer to influence the grain size is also referred to as seeding.
  • WO 00/56416 a method for controlling the grain size in the continuous mass crystallization is known, which is also intended for the production of coarse ammonium sulfate crystals in an Oslo crystallizer or DTB crystallizer and in which similar to the method according to EP 0632738 B1 an inoculation is carried out with externally supplied crystal suspension.
  • the inoculum is a crystallizate, which is manufactured in its parameters independent of the current crystallization process and which has a mean grain diameter of 0.1 - 1, 0 mm.
  • the temperature of the seed product during the addition must not be in this process above the operating temperature in the crystallizer, but must be up to 40 0 C, preferably 10 - 30 0 C, lower.
  • a suspension with a solids content in the desired particle size is continuously withdrawn and separated by centrifugation in product and mother liquor, wherein the mother liquor is conveyed to an intermediate container and fed back from there into the circulation line of the external circuit of the crystallizer.
  • the seed product is preferably added in an amount whose solids content is 5 to 30% by weight of the solid discharged from the crystallizer in each case.
  • the solids content of the seed product can be generated, for example, by mechanically comminuting a portion of the product crystals and / or by a separate crystallization stage.
  • JP 2005-194153 A a designed as a DTB crystallizer plant for the production of ammonium sulfate crystallizate is known in which a to a Clarifying zone of the crystallizer connected external circuit is provided for clarified solution in which either a heat exchanger or a supply line for solvent (eg water or undersaturated ammonium sulfate solution) is optionally installed to dissolve the solid content contained.
  • the clarification zone is connected directly or indirectly via the external circuit to a further discharge line, with which a suspension containing as solid only fine crystals, can be completely discharged from the process, for example, to obtain fine-grained ammonium sulfate product.
  • a third discharge line is connected, can be deducted in the case of need, an excess of crystallization nuclei and ultrafine crystals and fed into a collection container.
  • Solvent is added to the receiver to dissolve the solids. From there, the resulting solution is passed into a neutralization tank in which it is treated with sulfuric acid and ammonia and heated by the associated neutralization reaction. The heated solution is then fed to the crystallizer.
  • Object of the present invention is to improve a generic method to the effect that the production of coarse-grained ammonium sulfate can be done with the least possible investment costs at the lowest possible periodic fluctuations in the mean grain size.
  • This object is achieved by a process for the continuous production of a coarse ammonium sulfate product (particle size d 'at least 2.4 mm) by crystallization of an ammonium sulfate solution in a operated according to the DTB principle crystallization stage in which a suspension of mother liquor and
  • Ammonium sulfate crystals is constantly circulated in an internal circuit upon evaporation of water and continuously withdrawn from the upper part of a clarified substream of solution in an external circuit, heated to dissolve the solids contained therein and returned as a clear solution back to the lower part of the crystallization stage is continuously withdrawn from the top of the crystallization stage, fresh solution is introduced from the outside into the crystallization stage and a partial stream of the suspension with the product crystal contained therein is withdrawn from the bottom of the crystallization stage and wherein according to the invention it is provided that the crystallization stage with a Suspensi - Onsêt in the soil area of over 40 M%, in particular over 42 M% is operated.
  • the suspension density is defined as the quotient of solid mass in the suspension and total mass of the suspension.
  • the suspension density in the bottom area which is equivalent to the density of the suspension withdrawn from the bottom area of the crystallization stage, is usually always in the range of, for example, about 25% by weight, depending on the crystallization stage, sometimes also in the range from 30 to at most 40 M%.
  • the mother liquor which is separated from the product crystallizate from the withdrawn suspension, recycled back into the crystallization stage.
  • undersize which is separated from the desired coarse grain by sieving after drying of the product crystal, should be redissolved in a portion of the condensed vapors of the crystallization stage and the resulting solution returned to the crystallization stage.
  • the suspension density in the crystallization stage can be determined by known measuring instruments; but it is also possible to monitor them via the current consumption of the drive motor of the circulating pump for the internal circuit.
  • Solution cycle can be advantageously provided to provide the heat for solids dissolution in the external circuit as heat of reaction by the fresh solution in the form of separately fed sulfuric acid and ammonia is supplied from the outside. As a result, can be completely dispensed with the separate supply of heat energy from the outside in the process.
  • the inventive method when the fresh solution, for. can be supplied from a caprolactam process, so is available as a waste product.
  • the method according to the invention makes it possible, with extremely simple means, to ensure safe process management with at least largely or even completely constant mean grain size of the product crystals in the coarse grain region. Inoculation of the internally circulated suspension with fine crystals and the required process and equipment costs can be completely dispensed with. However, the instead required higher use of drive energy for the internal suspension circuit is overcompensated by the advantage of a very uniform coarse grain production with high yield by far.
  • Core of the illustrated system is a DTB crystallizer 1, the head is denoted by 4 and the bottom portion with 2.
  • a flow guide tube 6 is arranged coaxially with the substantially cylindrical jacket of the crystallizer housing.
  • the liquid level not shown is enclosed in operation plant in the region of the upper end of the Strömungsleitrohrs 6, at the lower end of a circulating pump 5 is arranged for an internal suspension circuit.
  • the circulation pump 5, the drive of which is flanged on the outside of the bottom of the crystallizer 1, is designed so that it can promote a suspension with a density of eg 45 M%.
  • a flow guide wall ending below the liquid level and forming an annular, downwardly open chamber is provided, which is decoupled from the internal suspension cycle in the sense of a clarification area 3 as a flow-calmed space.
  • this annular clarification chamber can also be divided by radial dividing walls into a plurality of partial chambers.
  • a line 7 of an external solution circuit is provided, which is provided with a circulating pump 8 and returns to the bottom area 2 of the crystallizer 1 in the vicinity of the lower end of the flow conduit 6.
  • an indirect heat exchanger 9 for solid solution in the clear solution in the line 7 is turned on.
  • the external supply of ammonium sulfate solution to the crystallizer 1 is designated 10 and leads directly into the bottom region 2; However, the solution feed line could also lead, for example, to the line 7 of the external solution circuit.
  • a vapor discharge line 1 1 is connected, which leads to an indirectly cooled condenser 12.
  • the coolant for example water
  • the withdrawn from the crystallizer 1 vapors can be performed as condensate from the condenser 12 by a Kondensatabtechnisch in a condensate collection tank 15 and collected there for subsequent reuse within (condensate line 17) or outside (condensate drain 16) of the plant.
  • a suspension withdrawal line 18 with a suspension pump 30 is connected to the crystallizer 1 in the bottom region 2.
  • the suspension withdrawal line 18 leads to a solid / liquid separation device 19, which may for example consist of a designed as a hydrocyclone thickener with downstream centrifuge.
  • the separated in the solid / liquid separator 19 mother liquor contained therein finely divided crystals can by a mother liquor discharge 27 in a release apparatus 24 are introduced while the separated solid is fed to a dryer 20 for drying.
  • the dry crystallizate coming from the dryer 20 reaches a screening device 21, in which the fraction of fine crystals contained is separated off from an ammonium sulphate product 22 having the desired coarse grain size spectrum.
  • the separated fine fraction is also conveyed via an undersize exhaust 23 as well as the liquid phase from the solid / liquid separator 19 into the dissolving apparatus 24. Since condensate can also be introduced via the condensate line 17 into the release apparatus 24, which is suitably equipped with a stirring apparatus, complete dissolution of the supplied solid to a reusable solution can be achieved.
  • Solution can be achieved by a e.g. designed as an overflow line solution line 25 a solution tank 26, which is also suitably provided with a stirrer, fed and returned from this by means of a feed pump 28 through a dissolution line 29 into the crystallizer 1.
  • the feed of the recirculated solution for example, as shown, take place in the vicinity of the annular clarification area 3 of the crystallizer 1.
  • a feed can also be particularly expedient, for example. be at the beginning of the line 7 of the external Wegsniklaufs, in which case a heating in the heat exchanger 9 can then take place before the introduction into the crystallization space.
  • a full Feststoffauf solution in the external circuit can also be part of the
  • Condensate from the condensate tank 15 are fed into the line 7 (not shown).

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Fertilizers (AREA)

Abstract

L'invention concerne la fabrication continue d'un produit sulfate d'ammonium à gros grains (22) par cristallisation d'une solution de sulfate d'ammonium lors d'un étage de cristallisation DTB (1), dans lequel une suspension de solution mère et de cristaux de sulfate d'ammonium est mise en circulation en continu dans un circuit interne (tube de guidage de flux (6), pompe de recirculation (5)) avec évaporation de l'eau et un flux partiel clarifié de solution est extrait de la partie supérieure (3) de l'étage de cristallisation dans un circuit externe (7), chauffé (9) pour dissoudre les solides qu'il contient et réintroduit sous la forme d'une solution claire dans la partie inférieure (2) de l'étage de cristallisation (1). Selon l'invention, des vapeurs (11) sont extraites en continu de la tête de l'étage de cristallisation, une solution fraîche (10) est introduite depuis l'extérieur dans l'étage de cristallisation et un flux partiel de la suspension contenant le produit cristallisé est extrait (18) de la zone de fond (2) de l'étage de cristallisation. Pour éviter des fluctuations cycliques du spectre granulométrique du produit cristallisé contenu dans la suspension extraite, il est proposé d'exploiter l'étage de cristallisation avec une densité de suspension dans la zone de fond supérieure à 40 % en moles, notamment supérieure à 42 % en moles.
PCT/EP2009/065454 2008-12-01 2009-11-19 Procédé de génération d'un produit sulfate d'ammonium à gros grains WO2010063584A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200810059754 DE102008059754A1 (de) 2008-12-01 2008-12-01 Verfahren zur Erzeugung eines grobkörnigen Ammoniumsulfat-Produkts
DE102008059754.6 2008-12-01

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WO2010063584A1 true WO2010063584A1 (fr) 2010-06-10

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WO (1) WO2010063584A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102627479A (zh) * 2012-04-13 2012-08-08 瓮福（集团）有限责任公司 一种大颗粒硫铵的生产方法
DE102011050288A1 (de) * 2011-05-11 2012-11-15 Crenox Gmbh Verfahren und Vorrichtung zur Abtrennung von Kristallen aus einer Lösung

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103395803A (zh) * 2013-08-01 2013-11-20 瓮福（集团）有限责任公司 一种粉状硫酸铵的生产方法
CN111408157B (zh) * 2020-04-14 2021-09-14 中石化南京工程有限公司 一种硫酸铵结晶方法及其装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988005028A1 (fr) * 1987-01-02 1988-07-14 Allied Corporation Production de cristaux de sulfate d'ammonium en granules ronds
JP2000072436A (ja) * 1998-09-04 2000-03-07 Mitsubishi Chemicals Corp 粗大硫安結晶の製造方法
WO2000056416A1 (fr) * 1999-03-20 2000-09-28 Domo Caproleuna Gmbh Procede de regulation de la taille de cristaux lors de la cristallisation de masse en continu
JP2005194153A (ja) * 2004-01-09 2005-07-21 Toray Ind Inc 硫安結晶の製造方法

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69300767T2 (de) 1992-03-27 1996-04-25 Allied Signal Inc Kristallisationsverfahren in einem umlenkkristallisator mit ablenkscheiben.

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988005028A1 (fr) * 1987-01-02 1988-07-14 Allied Corporation Production de cristaux de sulfate d'ammonium en granules ronds
JP2000072436A (ja) * 1998-09-04 2000-03-07 Mitsubishi Chemicals Corp 粗大硫安結晶の製造方法
WO2000056416A1 (fr) * 1999-03-20 2000-09-28 Domo Caproleuna Gmbh Procede de regulation de la taille de cristaux lors de la cristallisation de masse en continu
JP2005194153A (ja) * 2004-01-09 2005-07-21 Toray Ind Inc 硫安結晶の製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
J. WIDUA, G. HOFMANN, S. WANG, W.: "Impf-Pass: Zyklische Korngrößenschwankungen in Massenkristallisatoren", CHEMIE TECHNIK, vol. 29, no. 8, 2000, pages 42 - 44, XP002570021 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011050288A1 (de) * 2011-05-11 2012-11-15 Crenox Gmbh Verfahren und Vorrichtung zur Abtrennung von Kristallen aus einer Lösung
CN102627479A (zh) * 2012-04-13 2012-08-08 瓮福（集团）有限责任公司 一种大颗粒硫铵的生产方法

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