EP0832986A1 - Process for regenerating ion exchange resins in the process of decalcifying sugar juices - Google Patents

Abstract

Process for decalcifying refined sugar syrup obtained during a sugar-making process comprises passing the sugar syrup containing Ca ions over a strong cationic ion exchange resin in Na<+> or K<+> form to replace the Ca ions by sodium and/or potassium ions, and subsequently regenerating the ion exchange resin by washing with dilute molasses.

Description

The present invention relates to a process for softening a sweet juice aqueous containing sugar and calcium ions and relates more particularly to a process for regenerating ion exchange resins in the process of decalcification of candy juices.

During the processes used in the manufacture of sugar, the juice is treated obtained by diffusion, from sugar beets transformed into cossettes, with lime. The spent pods are pressed to give pulp. Lime introduced into the juice is transformed, by introduction of carbon dioxide, into calcium carbonate. The calcium carbonate is removed by filtration. However, this elimination is only partial and a certain amount of calcium compounds remains dissolved in the juice in the form of soluble calcium salts. These calcium salts have a certain solubility which decreases when the concentration of dry matter increases, which occurs during evaporation and crystallization stages. In precipitating, these calcium salts scale up the material and lower the coefficient of heat transfer, which causes partial disturbances in the equilibrium of the economy of the sugar refinery. In addition, they create a cloud in the crystallized sugar obtained during the process.

Decalcification is therefore necessary to keep the equipment clean and obtain quality sugars, that is to say without cloudiness. Calcium ions are exchanged by means of ion-exchange resins with sodium and / or potassium ions, and the resin is then regenerated. Regeneration was first carried out with brine, NaCI, but this mode of regeneration is now abandoned in the most countries because it generates waste water loaded with chlorides.

Two types of regeneration are currently used, Akzo or NRS process and the Gryllus process.

The Akzo process, consisting of a regeneration with soda, results in a significant expenditure of soda and an increase in the coloring of purified juices.

According to the Gryllus process, regeneration is carried out with a Poor Sewer II. The disadvantages of the Gryllus process are precipitation of calcium salts into third jet, recycling to Standard Liquor 1 (LS1) and a cloud in the sugar of first draft.

The present invention overcomes the problems of regeneration techniques of prior art.

According to the process of the present invention, molasses is used for the regeneration of ion exchange resins in the juice decalcification process of candy.

The present invention therefore provides a process for decalcifying purified sugar juice from a sugar manufacturing process, originating from the filtration stages, in which said juice, containing calcium ions, is sent to a strong cationic ion exchange resin. in Na ⁺ or K ^{+ form} , where calcium ions are replaced by sodium and / or potassium ions, and in which said ion exchange resin is then subjected to regeneration (or washing), said process being characterized in that diluted molasses are used to effect said regeneration (or said washing) of said ion exchange resin.

This molasses is advantageously part of the molasses obtained during of the sugar making process.

If the installation includes a distillery, all the products leaving the decalcification and used for regeneration are sent directly to the distillery. There is no recycling of eluate in purification. In this case the first variant described below will be advantageously used.

Conversely, if the installation does not include a distillery, the diluted fractions are used for diluting turbinated molasses (for regeneration). In this case second variant described below will preferably be used.

According to a first variant of the invention, the molasses is sent in the step co-current regeneration.

According to the first variant of the present invention, the molasses is preferably diluted to around 70 to 80 brix (percent dry matter), better yet at around 76 brix, before being sent to the decalcification stage to regenerate the ion exchange resin.

According to this first variant of the present invention, molasses is advantageously reheated to a temperature of about 80 to 90 ° C, better still at about 85 ° C, before being sent to the decalcification step to regenerate the resin ion exchange.

According to the first variant of the invention, the regeneration of the resin ion exchange is carried out while the resin is dry, i.e. the resin bed has been drained and is therefore dry. An ion exchange resin is said to be "dry" when it does not include interstitial fluid (water or, in this case, juice).

As far as the Applicant knows, in the prior art, no Ion exchange resin regeneration had not been carried out on a dry resin. He has therefore had to overcome an important prejudice to apply the above provisions of the first variant of the present invention.

According to another advantageous arrangement of the first variant of this invention, a molasses cake is formed which is sent to the resin in order to to eliminate with the minimum of mixing, i.e. dilution, the diluted juice contained in the resin.

According to yet another advantageous arrangement of this first variant of the invention, after regeneration, the resin is brought to dryness, by a total emptying of the resin can, and the resin is washed dry with a cake of purified juice.

The calcified molasses used to regenerate the ion exchange resin of the decalcification step is mixed with molasses from the process, i.e. turbinated molasses, to obtain a concentration equal to approximately 80% of dry matter, and is sent to storage.

According to a second variant of the invention, the molasses is sent in the step counter-current regeneration.

According to the second variant of the present invention, the molasses is preferably diluted to around 60 to 65 brix, better still to around 62 brix, before being sent to the decalcification step to regenerate the ion exchange resin.

According to this second variant of the present invention, molasses is advantageously sent at a temperature of about 50 to 60 ° C, better still at about 55 ° C, before being sent to the decalcification step to regenerate the resin ion exchange.

Before the actual regeneration, the resins undergo a total emptying then are washed dry with a small amount of water (about 0.2 BV).

According to the second variant of the invention, the washing of the exchange resin ion is carried out while the resin is dry, i.e. the resin bed has been drained and is therefore dry. An ion exchange resin is said to be "dry" when it does not includes no interstitial fluid (water).

As far as the Applicant knows, in the prior art, no washing ion exchange resin had not been carried out on a dry resin. So it took overcome an important prejudice to apply the above provisions of the second variant of the present invention.

According to yet another advantageous arrangement of this second variant of the invention, after regeneration (washing), the resin is brought to dryness, by emptying of the resin canister, and the resin is washed dry with several successive patties of water.

The calcified molasses used to regenerate the ion exchange resin of the decalcification step is mixed with molasses from the process, i.e. turbinated molasses, to obtain a concentration equal to approximately 80% of dry matter, and is sent to storage.

If desired, lime salts can be removed from the calcified molasses from the regeneration of the ion exchange resin by carbonating simply said molasses and separating the calcium carbonate formed.

The process of the present invention can be used both in the beet sugar as in cane sugar.

The present invention will now be illustrated with reference to the appended Figure, schematically representing a sugar manufacturing process, given as example, according to, respectively, the first or the second variant of the present invention.

According to the first variant, the purified juices JE originating from the filtration stages (generally two in number), containing sodium, potassium and calcium ions, are sent by 1 to a DK decalcification stage, designated by 2. During the DK decalcification step, the calcified juices pass over an ion exchange resin (not shown). The juices, free of calcium ions and still containing sodium and potassium ions, leaving the decalcification by 3, are about 15% dry matter. These juices before evaporation are designated by JAE. The JAEs are sent by 3 in an evaporation step with several effects 4, generally five in number (not shown), from which emerges by 5 a syrup with approximately 72 to 74% of dry matter. This syrup receives the redesigns of sugar from third spray and possibly from second spray, as will be shown below, to constitute Standard Liquor 1 (LS1), which will feed the first crystallization spray. The LS1 is sent by 5 in a first jet cooking appliance 6, containing the Masse Cuite I (MC _I ). The MC _I leaving at 7 from the first jet cooking appliance 6 is sent to a discontinuous first jet turbine 8 where it is added with water H ₂ O at 9. At exit 10 from the first jet turbine 8, first-throw sugar, Sucre I or S _I , is recovered, as well as in 11, a mother liquor of MC _I , designated by Poor Sewer I (EP1). This EP1 also constitutes the LS2 (Standard Liquor 2). The EP1 (or LS2) is sent to a second jet cooking appliance 12, containing the Masse Cuite II (MC _II ). The MC _II leaving through 13 from the second jet cooking appliance 12 is sent to a continuous second jet turbine 14. At the output 15 of the second jet turbine 14, second jet sugar Si is recovered, as well as 16 a mother liquor of MC _II , designated by Poor Sewer II (EP2). The second jet sugar S _II is recycled by 15 'in the standard liquor LS1. The EP2 is sent by 16 in a third jet cooking appliance 17 containing the Massecuite III (MC _III ) · The MC _III leaving by 18 of the third jet cooking appliance 17 is sent in a block of vertical mixers 19, generally three in number (not shown individually), then by 20 on a continuous turbine 21. At the outlet of the continuous turbine 21, we recover by 22 brown sugar SR, which is returned to the Standard Liquor 1 by 22 ', and, by 23, turbines molasses M _T.

According to the first variant of the present invention, part of the turbines molasses M _T , obtained between 82 and 86 brix, generally around 84 brix, is diluted with dilution juice of JDM molasses originating by 24 from washing the resin. ion exchange up to about 35 brix, and sent by 25 to the decalcification step 2 to regenerate the co-current ion exchange resin. The calcified molasses M _C leaving the decalcification 2 by 26 after regenerating the ion exchange resin is mixed with the turbinated molasses M _T to obtain a molasses having a concentration greater than about 78 to 80% of dry matter which is sent to the storage by 27.

The theoretical regeneration yield R _t , that is to say the ratio [equivalent of regeneration cation] to [equivalent of Ca ⁺⁺ eliminated] is 1.34. Table 1 below indicates the practical values obtained for the practical regeneration yield R _P in the process of the present invention and the various processes of the prior art. Process R _p NaCI 5-10 Gryllus 4-7 Akzo 2.0-3.0 Present co-current invention 4.0

According to the second variant, the purified JE juices coming from the filtration stages (generally two in number), containing sodium, potassium and calcium ions, are sent by 1 to a DK decalcification stage, designated by 2. During the DK decalcification step, the calcified juices pass over an ion exchange resin (not shown). The juices, free of calcium ions and still containing sodium and potassium ions, leaving the decalcification by 3, are about 15% dry matter. These juices before evaporation are designated by JAE. The JAEs are sent by 3 in an evaporation step with several effects 4, generally five in number (not shown), from which emerges by 5 a syrup with approximately 72 to 74% of dry matter. This syrup receives the redesigns of sugar from third spray and possibly from second spray, as will be shown below, to constitute Standard Liquor 1 (LS1), which will feed the first crystallization spray. The LS1 is sent by 5 in a first jet cooking appliance 6, containing the Masse Cuite I (MC _I ). The MC _I leaving at 7 from the first jet cooking appliance 6 is sent to a discontinuous first jet turbine 8 where it is added with water H ₂ O at 9. At exit 10 from the first jet turbine 8, first-throw sugar, Sucre I or S _I , is recovered, as well as in 11, a mother liquor of MC _I , designated by Poor Sewer I (EP1). This EP1 also constitutes the LS2 (Standard Liquor 2). The EP1 (or LS2) is sent to a second jet cooking appliance 12, containing the Masse Cuite II (MC _II ). The MC _II leaving through 13 from the second jet cooking appliance 12 is sent to a continuous second jet turbine 14. At the output 15 of the second jet turbine 14, sugar from the second jet S _II is recovered, as well as in 16 a mother liquor of MC _II , designated by Poor Sewer II (EP2). The second jet sugar S _II is recycled by 15 'in the standard liquor LS1. The EP2 is sent by 16 in a third jet cooking appliance 17 containing the Mace III (MC _III ) The MC _III leaving by 18 from the third jet cooking appliance 17 is sent in a block of vertical mixers 19 , generally three in number (not shown individually), then by 20 on a continuous turbine 21. At the outlet of the continuous turbine 21, we recover by 22 brown sugar SR, which is returned to the Standard Liquor 1 by 22 ' , and, by 23, turbinated molasses M _T.

According to the second variant of the present invention, part of the turbines molasses M _T , obtained between 82 and 86 brix, generally around 84 brix, is diluted with dilution juice of JDM molasses originating by 24 from washing the resin. ion exchange, and sent by 25 to the decalcification step 2 to regenerate the ion exchange resin against the current. The calcified molasses M _C leaving the decalcification 2 by 26 after regenerating the ion exchange resin is mixed with the turbinated molasses M _T to obtain a molasses having a concentration greater than about 78 to 80% of dry matter which is sent to the storage by 27.

The theoretical regeneration yield R _t , that is to say the ratio [equivalent of regeneration cation] to [equivalent of Ca ⁺⁺ eliminated] is 1.34. Table 2 below indicates the practical values obtained for the practical regeneration yield R _P in the process of the present invention and the various processes of the prior art. Process R _p NaCI 5-10 Gryllus 4-7 Akzo 2.0-3.0 Present invention against the grain 2.0 to 3.0

The following Examples describe the invention without limitation.

Example 1 (concerning the first variant)

a) Afin de permettre un brassage efficace sans perdre de résine vers le piège à résine, au démarrage de la régénération, on effectue une vidange partielle du bidon. De l'air détendu à 2,5 10^-2 mPa (2,5 bars) est envoyé dans le bidon. On arrête la vidange partielle environ 30 cm au-dessus du niveau des résines;

b) On effectue ensuite un dégazage, pour casser la pression dans le bidon par mise à l'atmosphère, ce qui permet à l'air à 0,5 10^-2 mPa (0,5 bar) de rentrer;

c) Un brassage à l'air permet de détasser la résine et de faire remonter en surface les impuretés en suspension dans le jus ainsi que les fines résines (cassées ou usées);

d) On effectue un "soulèvement" au JAE pour chasser les impuretés et fines qui se sont accumulées en partie supérieure du bidon lors du brassage à l'air;

e) On effectue ensuite une vidange totale du lit de résine. L'intérêt de la vidange totale est de récupérer le plus possible de JAE restant dans le bidon, ceci afin de limiter pour la régénération ultérieure, le mélange de produit à brix faible (JAE) avec le produit à brix élevé (mélasse) pour réduire le plus possible la quantité de produit à brix intermédiaire (c'est-à-dire un produit entre environ 20 et 80 brix). En effet, il n'est pas souhaitable de stocker de produits à brix intermédiaire avec la mélasse car il y aurait des problèmes de conservation dus au brix final trop faible. D'autre part, si ces produits à brix intermédiaire étaient recyclés en amont du procédé en quantité importante, ils pourraient perturber l'épuration;

f) Le bidon est alors mis à l'atmosphère pour casser la pression suite à la vidange totale;

g) La mélasse brute M_B est diluée avec du JDM à 76 brix à chaud. Cette mélasse est ensuite réchauffée jusqu'à 85°C et envoyée à la régénération;

h) La mélasse réchauffée à 85°C est envoyée par l'entrée haute du bidon, afin de constituer une galette. Cette galette entre progressivement dans le lit de résine. Un effet de "piston" est obtenu, ce qui a pour effet de chasser le JAE à l'intérieur des billes de résine et de le chasser vers le fond du bidon; L'éluat, constitué par un mélange de JAE et de mélasse, sort du bidon et est collecté dans un bac à mélasse diluée jusqu'à 55 brix;

i) Après régénération, le bidon de résine échangeuse d'ions est à nouveau vidangé et dégazé. On remplit ensuite le bidon de Jus avant Décalcification (JAD) de désucrage qui chasse la mélasse emprisonnée dans les billes de résine vers le fond du bidon;

j) L'éluat sort vers un bac à Mélasse Calcifiée jusqu'à 55 brix;

k) Pour effectuer une phase de désucrage, le bidon est ensuite alimenté avec du JAD. Les éluats jusqu'à 35 brix sont collectés dans un bac à Mélasse Diluée Recyclée (MDR) puis, après temporisation, vers le bac JDM jusqu'à un niveau de consigne. Le bidon est alors de nouveau alimenté avec du JAD, jusqu'à 22 brix.

The decalcification ion exchange resin bed containing resin, with a resin trap, in the form of beads is contained in a container;

a) In order to allow efficient mixing without losing resin to the resin trap, at the start of the regeneration, a partial emptying of the container is carried out. Relaxed air at 2.5 10 ^-2 mPa (2.5 bar) is sent to the container. Partial emptying is stopped about 30 cm above the level of the resins;

b) degassing is then carried out to break the pressure in the container by venting, which allows air at 0.5 10 ^-2 mPa (0.5 bar) to enter;

c) Air mixing allows the resin to be loosened and the impurities suspended in the juice as well as the fine resins (broken or worn) to rise to the surface;

d) A "lifting" is carried out at the JAE to drive out the impurities and fines which have accumulated in the upper part of the can during air mixing;

e) A complete emptying of the resin bed is then carried out. The advantage of total emptying is to recover as much of the JAE remaining in the container as possible, this in order to limit, for subsequent regeneration, the mixture of product with low brix (JAE) with the product with high brix (molasses) to reduce as much as possible the quantity of product at intermediate brix (that is to say a product between about 20 and 80 brix). Indeed, it is not desirable to store products with an intermediate brix with molasses because there would be conservation problems due to the final brix being too low. On the other hand, if these intermediate-priced products were recycled upstream of the process in large quantities, they could disturb the purification;

f) The container is then vented to relieve the pressure following total emptying;

g) The raw molasses M _B is diluted with JDM at 76 brix while hot. This molasses is then reheated to 85 ° C and sent to regeneration;

h) Molasses warmed to 85 ° C is sent through the upper inlet of the container, to form a pancake. This cake gradually enters the resin bed. A "piston" effect is obtained, which has the effect of driving the JAE inside the resin beads and driving it towards the bottom of the can; The eluate, consisting of a mixture of JAE and molasses, leaves the container and is collected in a molasses tank diluted up to 55 brix;

i) After regeneration, the can of ion exchange resin is again drained and degassed. Then fill the can with Juice before Decalcification (JAD) of sugar removal which drives the molasses trapped in the resin beads towards the bottom of the can;

j) The eluate leaves towards a Calcified Molasses tank up to 55 brix;

k) To carry out a desugaring phase, the container is then supplied with JAD. Eluates up to 35 brix are collected in a Recycled Diluted Molasses tank (MDR) then, after delay, to the JDM tank up to a set level. The container is then again supplied with JAD, up to 22 brix.

Phases a), b), c) and d) above are then repeated.

Example 2 (concerning the second variant)

g) Un lavage avec une faible quantité d'eau (0,2 BV) est réalisé sur le lit de résine à sec afin de mieux séparer le JAE de la mélasse;

h) La mélasse brute M_B est diluée avec du JDM à 62 brix. Cette mélasse à 55°C est envoyée à la régénération pour passer à contre-courant à la vitesse de 1,5 BV/h. Le volume à passer est de 1,7 BV;

i) Après régénération, le bidon de résine échangeuse d'ions est à nouveau vidangé et dégazé;

j) Les résines sont alors lavées 4 fois avec 0,18 BV d'eau. Les éluats sont collectés dans le bac de JDM.

k) Un contre-courant au JAD permet de récupérer une fraction diluée (jusqu'à 15 brix) envoyée à l'épuration. Ce bidon est régénéré et prêt à l'emploi.

I) Le JDM sert à diluer la mélasse pour la régénération. L'excédent est utilisé au niveau du 3ème jet pour effectuer des dilutions (sortie de cuite - en malaxeur) ou des clairçages en turbine.

Phases a) to f) are carried out, as in Example 1 above. The following phases are then carried out:

g) Washing with a small amount of water (0.2 BV) is carried out on the dry resin bed in order to better separate the JAE from the molasses;

h) The raw molasses M _B is diluted with JDM at 62 brix. This molasses at 55 ° C is sent to the regeneration to pass against the current at the speed of 1.5 BV / h. The volume to pass is 1.7 BV;

i) After regeneration, the can of ion exchange resin is again drained and degassed;

j) The resins are then washed 4 times with 0.18 BV of water. Eluates are collected in the JDM bin.

k) A counter-current at the JAD makes it possible to recover a diluted fraction (up to 15 brix) sent for treatment. This container is regenerated and ready to use.

I) JDM is used to dilute molasses for regeneration. The excess is used at the level of the 3rd jet to carry out dilutions (out of cooked - in mixer) or clearings in turbine.

Phases a), b), c) and d) are then repeated.

Those skilled in the art will understand that although the invention has been described and illustrated for particular embodiments, many variants can be envisaged while remaining within the framework of the invention as defined in the appended claims.

Claims (16)

Method for decalcifying purified sugar juice from a sugar manufacturing process, in which said juice, containing calcium ions, is sent to a strong cationic ion exchange resin in Na ⁺ or K ^{+ form} , where calcium ions are replaced by sodium and / or potassium ions, and in which said ion exchange resin is then subjected to a regeneration (or washing), said method being characterized in that said regeneration of said ion exchange resin is carried out with diluted molasses. Method according to claim 1, characterized in that said molasses is part of the molasses obtained in said sugar manufacturing process. Method according to one of claims 1 and 2, characterized in that calcified molasses, used for the regeneration of the ion exchange resin, is mixed with molasses from the process to obtain a concentration equal to around 80% dry matter to be sent to storage. Method according to any one of Claims 1 to 3, characterized in that that molasses is sent to the co-current ion exchange resin. Method according to claim 4, characterized in that said molasses is diluted to around 70 to 80 brix (percent dry matter). Method according to one of claims 4 and 5, characterized in that said molasses is reheated to a temperature of about 80 to 90 ° C. Process according to any one of Claims 4 to 6, characterized in that that said regeneration is carried out on said dry ion exchange resin. Method according to any one of Claims 4 to 7, characterized in that that, for regeneration, said molasses is sent to said exchange resin of ions in the form of a pancake. Method according to any one of Claims 4 to 8, characterized in that that after regeneration, the ion exchange resin is brought to dryness and is washed dry with purified juice in the form of a cake. Method according to any one of Claims 1 to 3, characterized in that that molasses is sent over the countercurrent ion exchange resin. Method according to claim 10, characterized in that said molasses is diluted to around 60 to 65 brix. Method according to one of claims 10 and 11, characterized in that said molasses is sent to a temperature of about 50 to 60 ° C. Method according to any one of claims 10 to 12, characterized in after regeneration, the ion exchange resin is brought to dryness and is washed with dry with water. Method according to any one of Claims 10 to 13, characterized in that the lime salts are removed from the calcified molasses coming from the regeneration of the ion exchange resin by carbonating said molasses and separating the calcium carbonate formed. Use of the method according to any one of Claims 1 to 14 in the manufacture of beet sugar. Use of the method according to any one of Claims 1 to 14 in the manufacture of cane sugar.

Images