RU2137842C1 - Method of producing primer seed suspension for sugar production massecuites - Google Patents

Abstract

FIELD: technology of sugar production. SUBSTANCE: method involves mixing syrup with ethanol up to formation of seeds charge and their growing in the mixture of syrup and alcohol. Syrup is prepared by dissolving the granulated sugar in desalted water up to supersaturation coefficient 1.15-1.20 followed by removal of impurities. After crystal growing in the mixture of syrup and alcohol the suspension is separated by centrifugation for two stages. At the first stage crystals (size is above 50 mcm) are removed and at the second stage the fraction of crystals (size is 10-50 mcm) is separated from an intercrystal solution having small crystals (size is less 10 mcm). Isolated crystal fraction is mixed with the prepared saturated sugar solution up to formation of the primer suspension. Invention can be used for the sugar crystallization. EFFECT: improved quality of the primer suspension, decreased consumption of ethyl alcohol.

Description

 The invention relates to sugar production technology and can be used in the crystallization of sugar.

A known method of obtaining a seed suspension of crystals for massecuite sugar production, involving the mixing of crystals with ethyl alcohol and a highly viscous substance - monoglyceride of fatty acids, grinding crystals in a mixture at a temperature of 40 - 50 ^o C [Ru, 2103371, C 13 F 1/02, 27.01. 1998].

 However, when the crystals are crushed, crystallization nuclei of various sizes and shapes are obtained, which negatively affects the quality of the crystals grown on these nuclei.

 Closest to the invention is a method for producing a seed suspension of crystals for massecuite sugar production, comprising adding a low molecular weight organic substance or a mixture of these substances, preferably ethyl alcohol, to sugar syrup having from 60 to 80% by weight of sucrose and from 20 to 40% by weight water, while the amount of organic mixture is sufficient to form an organic mixture: water ratio by weight of from 0.6: 1 to 3: 1, preferably from 1.2: 1 to 1.6: 1, respectively [US, 4164429, C 13 F 1/02, 08/14/1979].

 The disadvantage of this method is that ethyl alcohol is added to the uncleaned sugar syrup entering the sugar crystallization stage, therefore, seed crystals do not always have the correct shape, and the crystallization rate is reduced compared to the crystallization rate in pure sugar solution. In addition, it is possible to obtain both small seed crystals with a size of less than 10 microns, and large crystals.

 The technical result of the invention is to improve the quality of the seed suspension containing single uniform crystals of the correct form, and to reduce the consumption of ethyl alcohol.

 This result is achieved by the fact that in the proposed method for producing a seed suspension of crystals for massecuite sugar production, mixing of syrup with ethanol is provided for the formation of crystal nuclei and their growth in a mixture of syrup with alcohol. A syrup is prepared by dissolving granulated sugar in demineralized water to achieve a supersaturation coefficient of 1.15 - 1.20, followed by separation of impurities from it. After growing crystals in a mixture of syrup with alcohol, the suspension is processed in a centrifugal field in two stages. In the first stage, crystals larger than 50 microns are removed from the suspension, and in the second stage, a fraction of crystals 10 to 50 microns in size is separated from the intercrystal solution with small crystals of less than 10 microns. The isolated crystal fraction is mixed with the prepared saturated sugar solution to form a seed suspension.

 The method is as follows.

Sugar syrup is prepared by dissolving granulated sugar in water for 20 to 25 minutes while maintaining a temperature of 90 - 102 ^o C and a pH of 6.5-8.0.

High temperatures (90 - 102 ^o C) and a long time of dissolution of granulated sugar (20 - 25 min) provide complete dissolution of all crystals and simultaneous partial sterilization of the sugar solution. PH values in the range of 6.5 - 8.0 correspond to a minimal decomposition of sucrose.

Sugar is dissolved in demineralized water in an amount necessary to create a supersaturation of 1.15 - 1.20 at a temperature of 20 -25 ^o C.

 Desalted water obtained by the ion exchange method creates further favorable conditions for sucrose crystallization, since crystals of high purity and regular shape will form in a pure solvent.

 The supersaturation coefficient values of 1.15 - 1.20 for supersaturated solutions correspond to a metastable supersaturation zone in which the growth of existing sucrose crystals is possible, but the crystals do not spontaneously nucleate.

 The resulting supersaturated syrup is separated from impurities by filtration or clarification in a centrifugal force field.

Clarified syrup was cooled to 20 - 25 ^o C, with stirring was added ethanol in an amount necessary to create supersaturation of 1.25 - 1.40 at a temperature of 20-25 ^o C, and the mixture was held at these conditions for 10 - 20 min.

Crystallization is carried out at a temperature of 20 - 25 ^o C, which does not require cooling or heating of the medium. In addition, the evaporation of alcohol and water will be minimal, since the indicated temperature is much lower than the boiling points of these liquids.

 The addition of ethyl alcohol reduces the solubility of sucrose and increases the supersaturation to 1.25 - 1.40, during which spontaneous nucleation of crystals occurs.

 Ethyl alcohol is preferable to other low molecular weight polar organic compounds because of its ability to completely and unlimitedly mix with water and non-toxicity. The amount of ethyl alcohol as a salting out reagent is small and does not require isolation from the mixture and return to the crystallization process.

 The seed crystals obtained by spontaneous nucleation at high saturation values have the correct shape and a very high degree of homogeneity, in contrast to the seed crystals obtained by grinding large crystals of sugar or in the form of icing sugar. In addition, the purity of crystals grown on seed crystals of the correct form is much higher, since the occlusion of intercrystal solution containing the majority of non-sugars is minimal.

 Holding the mixture for 10 to 20 minutes ensures the growth and fixing of crystals, which, when introduced into the apparatus as seed crystals at the stage of basic crystallization, are almost completely preserved.

 The resulting suspension is divided into two stages in the field of centrifugal forces to obtain uniform crystals with a size of 10 - 50 microns.

 In the first stage, large crystals larger than 50 microns are removed from the suspension. At the second stage, a fraction of crystals with a size of 10-50 μm is separated from the intercrystal solution with small crystals of less than 10 μm.

 The homogeneity of the crystals of the selected fraction provides further uniform crystallization at the stage of main crystallization.

The isolated crystal fraction is mixed with pre-prepared filtered saturated sugar solution to form a seed suspension. Store the seed suspension at a temperature of 20 - 25 ^o C.

 A saturated sugar solution ensures the preservation of seed crystals, since crystals in a saturated solution do not grow and do not dissolve.

Example. Take 1 liter of water, previously desalted by ion exchange, with a temperature of 100 ^o C, add 2.38 kg of sugar, incubated with stirring for 20 minutes at a temperature of 100 ^o C and a pH of 7.2. The resulting syrup is filtered and cooled to 23 ^o C. Sugar syrup contains SV = 67.04%, the coefficient of syrup supersaturation K _per = 1.17.

To the resulting syrup add 605 ml of 96% volume of ethyl alcohol to K _per = 1.33 at 23 ^o C and incubated for 15 minutes to form crystals.

 The resulting suspension is separated in a laboratory filter centrifuge with a mesh size of 55 microns to remove crystals greater than 50 microns. Then, intercrystal solution with crystals less than 10 microns is separated on hydrocyclones. Crystals of 10-50 microns in size are washed with alcohol, dried and weighed. Receive 420 g of crystals with a size of 10 to 50 microns.

The resulting crystals are mixed with 630 g of a filtered saturated solution in the form of a syrup with a content of CB = 67% and a temperature of 23 ^o C.

 In parallel, the process is carried out by a known method.

 Using the proposed method allows to obtain a high-quality seed suspension containing single uniform crystals of the correct form, and to reduce the consumption of ethyl alcohol in 2 to 4 times.

Claims (1)

 A method of obtaining a seed suspension of crystals for massecuite massecuite, comprising mixing syrup with ethanol to form crystal nuclei and growing them in a mixture of syrup with alcohol, characterized in that the syrup is prepared by dissolving granulated sugar in desalted water to achieve a supersaturation ratio of 1.15 - 1.20, followed by separation of impurities from it and after growing the crystals in a mixture of syrup with alcohol, the suspension is divided into two stages in the field of centrifugal forces, while the first stage consists of suspension In this process, crystals larger than 50 μm are removed, and in the second stage, a fraction of crystals 10 - 50 μm in size is separated from the intercrystal solution with small crystals of less than 10 μm, and the isolated crystal fraction is mixed with the prepared saturated sugar solution to form a seed suspension.