RU2196831C1 - Method of producing syrup from sugar-containing raw material - Google Patents

Abstract

FIELD: sugar industry; applicable for production of syrup from sugar-containing raw material. SUBSTANCE: method involves extraction of ground sugar-containing raw material by extracting agent at their mass ratio 1:1.4-1: 3.5. Before condensing, prepared diffused juice is softened on cationite and concentrated by reverse osmosis or by nanofiltration up to 20-40% of dry substances. Selected as extracting agent is water with total content of salts not more 30 mg/l. It is advisable to clarify softened diffused juice before concentration on anionite or by activated carbon. EFFECT: reduced wastes of saccharose in pulp, improved quality of syrup; reduced expenditures for process. 3 cl, 1 tbl

Description

 The invention relates to the sugar industry and can be used for the production of syrup from sugar-containing raw materials.

 Currently, the sugar industry uses various methods for the production of syrup, with the aim of reducing the loss of sucrose in the process of processing raw materials, improving the quality of the syrup, reducing its cost and ultimately increasing the yield and cost of commodity sugar.

 So known is a method involving the extraction of crushed raw materials with water to obtain diffusion juice, its purification from mechanical impurities, cooling, ultrafiltration of the juice with the formation of ultrafiltrate and concentrate, which is subjected to electrolysis to coagulate the high molecular weight compounds (IUDs) and colloid-dispersed substances contained in it, followed by sedimentation of the coagulant in the sump, filtering the solution with the filler separated from the precipitate and returning it to the process by mixing with the original juice. The resulting ultrafiltrate is concentrated to syrup by reverse osmosis and deionization of the syrup is carried out by electrodialysis in two stages (Auth. St. 482496, class C 13 D 3/16, 1975).

 The disadvantages of the method are as follows. In the process of extraction, juice is obtained with a high content of hardness ions and colloidal dispersion substances. The rate of ultrafiltration of such a juice decreases rapidly as the ultrafiltrate is taken, which is due to the blocking of the pores of the membranes with colloidal dispersion substances and sparingly soluble hardness salts. This necessitates frequent flushing of ultrafiltration equipment, the formation of environmentally dirty drains.

 In the process of electrocoagulation, the juice quality decreases due to the additional transition of metal ions into the juice, which are not retained by ultrafiltration. The operation of concentrating the ultrafiltrate is carried out with low efficiency due to the rapid blocking of membranes with hardness salts, which also necessitates frequent washing of equipment.

 The implementation of this method leads to high operating costs, high cost of the produced syrup.

 There is also known a method involving the extraction of sucrose from sugar-containing raw material shavings with water with a salt content of not more than 30 mg / l, to obtain diffusion juice, its cooling, ultrafiltration in several stages with dilution of the juice before the first stage and the concentrate formed at each stage with the above water. In this case, the ultrafiltrates obtained in the stages are mixed, then the combined ultrafiltrate is softened and concentrated by the reverse osmosis method to obtain a syrup with a solids content of 30-50% and a filtrate having a salt content of not more than 30 mg / l, followed by its use in the extraction process and ultrafiltration. (Patent of the Russian Federation 2118664 C 13 D 3/16 for the invention "Method for the production of syrup from sugar-containing raw materials" - 1997).

 The specified method also has several disadvantages. The extraction process is carried out in such a way that the resulting pulp contains a sufficiently large amount of sucrose, while many non-sugars: hydratopectin, IUDs, acids and others, pass into the diffusion juice from the chips. As a result, for example, in beet sugar production, the sucrose loss in beet pulp reaches 0.3-0.5% by weight of beets, and the benignness (purity) of diffusion juice is 85-86%.

 Purification of such juice by ultrafiltration with dilution requires the use of expensive equipment and high maintenance costs for its maintenance: washing the membranes, disposing of the resulting washing effluents, etc. In this case, sucrose is lost in the amount of 0.2-0.4% with the concentrate after the last ultrafiltration stage to the mass of beets. In addition, in the process of purification, a combined ultrafiltrate is obtained with a low content of CB ~ 2.4%, to thicken which a large number of expensive reverse osmosis plants are required.

The closest technical solution to the proposed one is a method involving the extraction of sucrose from crushed raw materials with water for 90-120 minutes with a mass ratio of raw materials and extractant 1: 0.8-1: 1.2. A mixture of water from a natural reservoir, pulp press water and steam condensate is used as an extractant. The resulting diffusion juice is cleaned of pulp and sent for defecation, where it is mixed with milk of lime. During defecation, some non-sugars decompose, coagulate, or are converted into sparingly soluble compounds that precipitate. Then the juice is saturated (saturated with carbon dioxide) in order to maximize the transfer of hardness ions to insoluble compounds and at the same time additional purification from non-sugars. Next, the juice is filtered and sulfitated. The total duration of defecation, saturation, filtration and sulfitation processes is 140-180 minutes. Sulphitated juice with a content of CB 12-14% is concentrated to a syrup with a content of CB 55-65% by evaporation at a temperature of 80-130 ^o C for 75-90 min (Vostokov A.I., Lepeshkin I.P., Beet sugar production - M ., Food Industry. 1973, p. 42).

 The specified method is selected as a prototype.

 This method, although widely used, has a number of significant drawbacks.

 The extraction process is carried out in such a way that the resulting pulp contains a large amount of sucrose, while many non-sugars: hydratopectin, IUDs, acids, colloids and others also pass into the diffusion juice from the raw materials. As a result, for example, in beet production, the sucrose loss in bagasse reaches 0.3-0.8% by weight of beets, and the benignity of the juice obtained is 82-86%.

 Juice purification is carried out using a large number of chemicals: lime milk, carbon dioxide. To obtain them, a special energy-intensive production is required for calcining limestone with a large cargo turnover (6-10% by weight of beets). The treatment process generates significant amounts of waste that cause serious environmental damage. During cleaning, the juice is very saturated with scale-forming hardness ions. The cleaning process requires the use of bulky equipment, large production and storage facilities, high labor costs. However, the overall effect of purifying juice from non-sugars is only 25-45%, and the benignity of purified juice in beet sugar production increases only to 87-89%. An increase in the ratio of the extractant mass to the sugar-containing raw material during extraction by more than 1.2: 1.0, which corresponds to a juice pumping factor of ~ 150%, is not economically profitable with the existing technology, since the evaporation of juice with a low dry matter content subsequently requires very high energy costs.

 In the process of evaporation, strong scale formation occurs on the heating surfaces, which causes an additional consumption of heating steam and fuel. In addition, there is a need for periodic shutdown of the enterprise for chemical washing of evaporation equipment, which leads to lost profit. The high total duration of processing of raw materials into syrup (3.5-4.5 hours) leads to additional losses of sucrose due to its thermal decomposition and hydrolysis, deterioration in the quality of the syrup.

 The above disadvantages cause the low quality of the syrup and high losses of sucrose during its production. In beet sugar factories, for example, the syrup has a purity of 86-89%, and the sucrose loss in the production of syrup is 1.8-2.8% by weight of beets.

 It became possible to solve the problem of eliminating the above disadvantages by creating a new original method for the production of syrup.

 The technical result of the claimed invention is to reduce the loss of sucrose in the pulp and in the processing of raw materials, improving the quality of the resulting diffusion juice and syrup, reducing the cost of producing syrup.

 This is achieved due to the fact that the proposed method for the production of syrup provides for the extraction of crushed sugar-containing raw materials with an extractant with a mass ratio of raw materials and extractant 1: 1.4-1: 3.5 to obtain diffusion juice, its purification from suspensions, softening, preliminary concentration of softened juice to the content of SV 20-40% reverse osmosis or nanofiltration, followed by thickening to SV 55-70% by evaporation. Softened juice before pre-concentration should be discolored with ion exchangers or activated carbon. It is also advisable to use desalted water with a salinity of not more than 30 mg / l as an extractant, which further increases the benign quality of diffusion juice.

 The proposed method is illustrated by the technological scheme depicted in the drawing, and is as follows.

 Water is taken from tank 1, and then, with the aid of installation 2, its hydrogen index (pH) is adjusted to the level of 5.5-6.5 (water is acidified) and sent to the extractor 3. The scalded, ground raw material is fed to the extractor against the flow of water. Extraction is carried out with a mass ratio of raw material and extractant 1: 1.4-1: 3.5 with a process duration of 25-60 minutes Under such conditions, they reduce the transition to the diffusion juice of non-sugars: hydratopectin, proteins, fats and other substances, increase the speed and depth of sucrose extraction.

 The result is a diffusion juice with a purity of 90-93%, CB content of 5-9%, while the sucrose loss in pulp is 0.05-0.15% by weight of the feedstock.

 The pulp resulting from the extraction process is removed from the extractor, pressed and used as animal feed. The pulp press water formed during pressing is purified by thermal, or chemical, or other known methods and is reused, for example, for washing, loosening ion-exchange resins.

 The diffusion juice obtained during the extraction process is cleaned of suspensions on the filter 4 and sent for softening to the installation 5 loaded with cation exchange resin in sodium or potassium form. The spent cation exchanger is regenerated with a solution of sodium or potassium salt. During the regeneration of cation exchange resin, solutions containing desorbed salts are obtained. These solutions are used to produce valuable products, for example magnesium chloride.

 If it is necessary to obtain a syrup with lower color, the softened juice should be discolored with anion exchange resin or activated carbon.

 The regeneration of anion exchange resin is carried out with a solution of salt, alkali (or their combined solution). The solutions formed during regeneration contain desorbed non-sugar. They are used to produce valuable substances, for example malic, citric acids.

 Activated carbon is regenerated after it is unloaded by thermal or thermochemical methods.

 Bleached juice with a purity of 93-96% is sent to the installation 7, where it is pre-concentrated to a content of 20-40% reverse osmosis or nanofiltration.

 The reverse osmosis filtrate formed during preconcentration is water with a salt content of not more than 30 mg / l, where sucrose is present in the form of traces, and which is returned to tank 1. Nanofiltrate is water with a salt content of ~ 60-100 mg / l, in which the sucrose concentration is 0.05-0.1%. Nanofiltrate is also returned to tank 1.

The pre-concentrated juice is fed to the evaporation unit 8, where it is finally concentrated to a syrup with a content of 55-70% CB. The duration of the evaporation process under vacuum is 20-45 min at a temperature of 80-100 ^o C. The finished syrup obtained from bleached juice has a purity of 92-94% and a color of 8-12 conventional units of optical density. A syrup from uncolored juice has a benignity of 90-92% and a color of 140-180 conventional units of optical density.

 The total loss of sucrose during the production of syrup is 0.2-0.4% by weight of the feedstock.

 Example 1

The scalded sugar beet chips with a sucrose content of 16.8% in an amount of 20 kg / h are fed to a laboratory extractor. Countercurrent shavings are supplied with water with a salinity of 250 mg / L and a pH of 6.1. Water consumption 28 kg / hour, while the mass ratio of raw materials and extractant is 1: 1.4. The temperature of extraction of 65 ^o C, the duration of 55 minutes

 Diffusion juice is taken from the extractor in an amount of 34 kg / h with the following indicators: CB content of 11.26%, sucrose 10.20%, benignness 90.6%. Loss of sucrose in the pulp is 0.15% by weight of beets. The juice is first cleaned of pulp on laboratory sieves, then of suspensions on a filter with a granular charge (sand with a particle size of 0.8 mm).

 After that, the juice is softened on an ion exchange resin of the KU-2-8 type in sodium form to a hardness of 0.1 mEq / kg. Softened juice is sent for bleaching, which is carried out on an ion-exchange resin of type AB-17 in chlorine form. Discolored juice has the following indicators: CB content of 11.0%, sucrose 10.19%, purity of 92.6%, chromaticity of 17 arbitrary units of optical density, hardness of 0.1 mEq / kg.

 Softened bleached juice with a flow rate of 34 kg / h is sent for pre-concentration, which is carried out in a laboratory reverse osmosis unit with elements of the 2540-LST-CPA2 brand from Hydronotics (USA). Working pressure is 35 atm. Select the filtrate with a flow rate of 21.3 kg / h. The result is a concentrated juice with a content of CB ~ 27.5%.

10 kg of pre-concentrated juice are taken and loaded into a laboratory evaporation unit operating under vacuum. Evaporation is carried out at a temperature of 88 ^o C for 40 minutes Get a syrup with the following indicators: SV content of 59.8%, sucrose 55.25%, purity 92.4%, color 22 standard units of optical density.

 Example 2

 The method is carried out as in example 1, but water with a salinity of 25 mg / l and a pH of 5.9 is supplied to a laboratory extractor with countercurrent shavings. With a mass ratio of raw materials and extractant 1: 1.4, the consumption of demineralized water will be 28 kg / h. The extraction time is also 55 minutes.

 Diffusion juice is taken from the extractor in an amount of 34 kg / h with the following indicators: 10.95% SV content, 10.23% sucrose, 93.4% good quality. Loss of sucrose in the pulp is 0.11% by weight of beets. The bleached juice has the following indicators: 10.5% SV content, 10.2% sucrose, 95.1% purity, 8 color units of optical density, hardness 0.08 mEq / kg.

 Softened bleached juice with a flow rate of 34 kg / h is sent for pre-concentration, which is carried out on a laboratory reverse osmosis unit with elements of the 2540-LST-CPA2 brand of the Hydronotics company Operating pressure 35 atm. Select the filtrate with a flow rate of 21.3 kg / h. The result is a concentrated juice with a CB content of 27.6%.

10 kg of pre-concentrated juice are taken and loaded into a laboratory evaporation unit operating under vacuum. Evaporation is carried out at a temperature of 88 ^o C for 40 minutes A syrup is obtained with the following indicators: CB content of 59.5%, sucrose 56.5%, purity 95%, chroma 18 units of conventional optical density.

 Example 3

 The method is carried out as in example 1, with the only difference being that scalded sugar beet chips in an amount of 20 kg / h with a sucrose content of 17% and a water with a total salt content of 15 mg / l and having a pH of 5.5 are fed to the extractor with a consumption of 70 kg / hour, providing a ratio of raw materials to extractant 1: 3,5. The duration of the extraction lasts 25 minutes

 Under such conditions, the following results were achieved.

 Diffusion juice was taken from the extractor in an amount of 76 kg / h with the following indicators: CB 5.04%, sucrose 4.76%, goodness 94.45%. Loss of sucrose in beet pulp is 0.06% by weight of beets. After softening and bleaching, the diffusion juice is obtained with the following indicators: CB content of 4.93%, sucrose 4.75%, good quality 96.3%, color 7 units of conventional optical density, hardness 0.03 mEq / kg.

 Softened bleached juice with a flow rate of 76 kg / h is sent for preliminary concentration on the above reverse osmosis unit. Selected 62.4 kg / h of filtrate. Get pre-concentrated juice with a content of CB 25%. After evaporation of the concentrated juice, a syrup is obtained with the following indicators: SV content of 61.3%, sucrose 58.9%, good quality 96.08%, color 16 units of conventional optical density.

 Example 4

 The method is carried out, as in example 1, with the only difference that the softened juice is sent to pre-concentration on the nanofiltration unit with elements of the ESPA brand of the company "Hydronotics". Working pressure is 8 atm. Select the filtrate with a flow rate of 20.5 kg / h. The result is a concentrated juice with a CB content of 26.8%, from which by evaporation a syrup with a CB content of 59.2%, sucrose 55.0%, a benign quality of 92.85%, a color of 160 arbitrary units of optical density are obtained.

 In reverse osmosis filtrates, sucrose is present in the form of traces, in the nanofiltrate the mass content of sucrose is 0.07%. The total loss of sucrose during the processing of sugar-containing raw materials into syrup in the above examples was from 0.1 to 0.4% by weight of beets.

 In all examples, during the evaporation process, no scale formation on heating surfaces was noted, as well as a decrease in the rate of selection of reverse osmosis filtrate and nanofiltrate.

 The results of the method are shown in the table.

 The analysis of the table and the data specified in examples 1-4 shows that with a decrease in salt content in water, the benign quality of diffusion juice and the resulting syrup increases. The same pattern is observed with an increase in the mass ratio of extractant to raw material and a decrease in the duration of extraction.

 A further increase in the mass ratio of extractant and raw material in excess of the declared in the method is not economically feasible due to the additional costs of pre-concentration.

 Thus, the proposed method reduces the loss of sucrose in the pulp and in the production process of syrup, improves the quality of the syrup, reduces the cost of its production.

Claims (3)

 1. A method for the production of syrup from sugar-containing raw materials, involving the extraction of crushed raw materials with an extractant to obtain diffusion juice, its purification from suspensions and thickening to a syrup with a content of ST 55-70% by evaporation, characterized in that the extraction is carried out at a mass ratio of raw material to extractant 1: 1.4-1: 3.5, to prevent the transition of organic non-sugars to juice, while prior to thickening, the juice is softened on cation exchange resin and concentrated by reverse osmosis or nanofiltration to an SV content of 20-40%.  2. The method according to p. 1, characterized in that as the extractant use desalted water with a total salt content of not more than 30 mg / L.  3. The method according to p. 1, characterized in that the softened diffusion juice before concentration is discolored on anion exchange resin or activated carbon.

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