RU2281334C1 - Method for purification of diffusion juice - Google Patents

Abstract

FIELD: sugar industry.

SUBSTANCE: claimed method includes juice predefecation up to pH 9.5-10.5, heating thereof at 70-85°C and feeding into flotator. Juice is held in flotator for 7-10 min to float precipitate released from juice with gas, and fed in defecation step. Juice and precipitate are separated using membrane made of high porous ceramic material comprising quartz fiber of 70-80 % porosity up to accumulation of precipitate layer on its surface and filtered juice is fed in defecation step. Defecated juice is saturated and filtered.

EFFECT: diffusion juice of increased purity and decreased chromaticity.

1 ex, 1 tbl

Description

The invention relates to the sugar industry. A known method of purification of diffusion juice, providing for progressive pre-defecation in two stages with an intermediate separation of the sediment by sedimentation of pre-defecated juice with a pH of 9.5-10.0 in the sump, defecation, 1 saturation, filtration, P saturation and filtration of the separated juice (Stangeev V.O. ., Kober V.T., Belostotsky L.G. et al. Modern Technologies and Equipment for Beet Sugar Production. Part 1, Kiev, Zukor Ukraini, 2003. - P.236-238).

The disadvantage of this method is the incomplete separation of the sediment before the main bowel movement and the insufficiently high effect of juice purification.

The closest analogue of the proposed method is a method for purification of diffusion juice, which provides for the progressive predefection of diffusion juice with the introduction of a solution of polyacrylamide when the pH of the juice is 9.5-10.0 in the amount of 0.09-0.011% by weight of the juice, deformed juice is defended, while the clarified juice sent to the main defecation, and the separated pre-defecated precipitate is mixed with a recirculating suspension of sediment 1 of saturation, 0.1-0.3% CaO is introduced into the mixture and saturated to pH 10.0-10.2, followed by filtration, the obtained filtrate lyayut to main liming, and the precipitate removed from the process, and then carry 1 carbonation, filtration carbonation juice 1, P saturation and the precipitate slurry recirculation 1 carbonation (RU 2105817 C1, C 13 D 3/02, 27.02.98).

The disadvantages of the method are the low cleaning effect and increased color of the purified juice. The disadvantage of this method is that this method does not make it possible to separate separately pre-defecate sediment with a small amount of lime and use its valuable feed properties.

The technical result of this invention is to increase the cleaning effect of diffusion juice and reducing the color of the purified juice.

The technical result is achieved in the proposed method, which provides for pre-defusion of diffusion juice, separation of sediment from pre-defecated juice, defecation, saturation and filtration of the separated juice by the fact that when the pH of the juice reaches 9.5-10.5 during pre-defecation, it is heated to 70-85 ° C , served in a flotator and incubated for 7-10 minutes to flotate the sediment with gas released from the juice. The juice is sent for defecation, and the juice with the sediment is separated using a membrane of highly porous ceramic material based on quartz fibers with a porosity of 70-80% until a sediment layer forms on its surface. Filtered juice is sent for defecation.

The method is as follows.

Diffusion juice is pre-defecated by alkalizing it with milk of lime in a pre-defecator and when the pH reaches 9.5-10.0, the juice is heated to 70-85 ° C (10-15 ° C above the initial temperature).

Heating pre-defecated juice with a pH of 9.5-10.0 has been found to reduce the stability of the colloidal system of diffusion juice. At the same time, alkalization to the indicated pH values ensures the formation of a precipitate consisting of calcium salts of organic acids, as well as part of protein and pectin substances. Since the proposed method does not provide for the return of juice 1 saturation or suspensions, the precipitate has a low density and can float. In addition, alkalization of the juice to pH values of 9.5-10.0 allows you to save the negative electrokinetic potential of the resulting precipitate, which is necessary for its subsequent separation.

It has been established that the indicated pH and temperature ranges make it possible to reduce the stability of protein substances and a number of other non-sugars, to saturate the juice volume with a sufficient number of microbubbles, which will then ensure sediment flotation, by reducing the solubility of gases.

When the juice is heated to 70-85 ° C, flotation of most of the sediment occurs. To complete this process, an extract of the juice for 7-10 minutes is provided. It is necessary to reduce the solubility of gases and conduct flotation of the precipitate due to the allocation of juice from the juice dissolved in it during the diffusion process and separation of the pulp.

The sediment is separated in a flotator consisting of two sections. In the first of these, extracts of the juice, as described above, are held. In the second section, the juice and the floated sediment are separated, and 70-90% of the juice is continuously separated from the bottom of the flotator and fed to the main bowel movement. Juice with sediment separated during flotation (30-10%) is sent for filtration. The separated precipitate refers to highly hydrated precipitates, the filtration of which on conventional filtering baffles is ineffective. Therefore, according to the proposed method, the separation of sediment from juice is carried out on a membrane filter with a membrane of highly porous ceramic material based on quartz fibers with a porosity of 70-80% until a sediment layer of 5-8 mm thickness is formed on the membrane surface.

The use of highly porous ceramic materials (VKM) based on quartz fibers to separate the precipitate formed is explained by the following.

New materials that have appeared recently open up opportunities for changing traditional technologies, including separation processes in the processing of plant materials. A feature of the separation of precipitation in sugar production using such a material is the occurrence of repulsive forces between the filtering wall and the resulting gel layer from the trapped particles.

The resulting effect of repulsion of particles and the formation of their layer on the surface of the filtering septum (membrane) is explained by the following. On fibers of pure amorphous quartz, a “siloxane” (Si — O — Si) surface is formed at room temperature. The free valencies of the molecules on this surface react with water in such a way that, as a result, the surface becomes coated with "silanol" (Si-OH) groups.

According to various researchers, the concentration of Si-OH groups on the smoothed, non-porous surface of silica is 4-5 groups per 1 nm ² , as a result, the surface is negatively charged. When the sample is heated to a temperature of 120-150 ° C, these groups are preserved. When heated to a higher temperature, the charge disappears, but when cooled in air or in solution, it reappears. The surface charge of microfibers of pure quartz can be 50 mV or more.

As a result of the interaction of a negatively charged filter surface and a negatively charged layer of trapped particles, a repulsive force arises that prevents the particles from approaching the pores of the membrane. Available materials allow you to conduct the process with a high filtration rate (0.8-1.2 m ³ / m ² hour) with a pressure drop of 0.1 MPa.

As you know, the substances of colloidal dispersion of diffusion juice have a negative electrokinetic potential. A negative charge persists when a small amount of lime is added to the juice. The proposed method is effective in cleaning diffusion juice of various quality, if the resulting precipitate will have a negative sign of the electrokinetic potential.

If the pulp is not completely removed from the diffusion juice, its particles do not stick to the membrane surface and do not clog it. Apparently, under these conditions, the particles of the pulp retain a negative charge. They accumulate in the layer of the formed precipitate, improving its structure, and then are removed from the technological process.

Purification of beet sugar juices with the help of already known membranes, including ceramic ones, is not used due to the fast clogging of their pores with delayed particles and difficulties with their subsequent regeneration.

The membrane material used in this method has unique properties: high porosity and negative electrostatic charge on the surface of the thin quartz filaments that make up its filter membrane. The porosity of the membrane used in the method is more than 10 times higher than the porosity of commercially available membranes. For example, at a membrane density of 400 kg / m ^3, its porosity is 76%.

Example 1

Diffusion juice is progressively alkalinized with lime in a predefiner until a pH of 9.5 is reached. Pre-defecated juice is heated in a heater to 80 ° C. Next, the juice is kept for 10 min to reduce the solubility of gases and conduct flotation of the precipitate in the flotator. Then 80% of the clarified juice is served for defecation and 1 saturation. The juice is filtered, and the precipitate is desugared on a vacuum filter. Carry out P saturation and control filtration.

The remaining amount of juice with sediment is fed into the collector and then into the filter, which is a trough, the wall of which is a membrane made of a highly porous ceramic material based on silica fibers with a porosity of 76%. The gutter is installed at an angle of 2 ° to the horizontal plane for the movement of sediment on it under the action of gravity.

A sediment layer of 6 mm thickness forms on the membrane surface, while the filtration rate is 0.9 m ³ / m ² h. The sediment from the trench enters the collector, and the clarified juice is sent for defecation.

In purified juice, indicators of its quality are determined. The results are shown in the table.

At the same time, the diffusion juice is cleaned according to a known method. Purified juice determines the purity, color and content of calcium salts.

Using the proposed method in comparison with the prototype allows to increase the cleaning effect on average by 6-8%, to improve the filtration and sedimentation characteristics of juice 1 saturation: to increase by 1.2 times the rate of sedimentation of juice 1 saturation and reduce its volume by 20-22%; reduce the color of purified juice by 8-11%, and the content of calcium salts in it by 17-20%.

Table Kind of juice Indicators Prototype Cleaning Cleaning by the proposed method Diffusion juice SV,% 12.5 12.5 H% 86.7 86.7 Pre-defecated juice pH ₂₀ 11.0 11.1 Settling rate, cm / min 4.8 - The volume of sediment,% 24.2 18.8 Saturation juice 1 Speed sedimentation, cm / min 3.6 3.9 The volume of sediment,% 25,4 18,4 Juice P Saturation PH ₂₀ 9.27 9.25 Content Ca salts,% CaO 0,038 0,030 RV,% by weight of juice 0.130 0.018 Color, conventional 18.6 16.8 H% 89.6 90.3

Claims (1)

A method for purifying diffusion juice, including pre-defecating it, separating the precipitate from pre-defecated juice, defecating, saturating and filtering the juice that has been eliminated, characterized in that when the juice reaches a pH of 9.5-10.5, it is heated to 70-85 ° C during pre-separation , fed to the flotator and incubated for 7-10 minutes to flotate the sediment with the gas released from the juice, while the juice is sent for defecation, and the juice and sediment are separated using a porous ceramic material based on quartz fiber porous awn 70-80% to form a precipitate at the surface layer and the filtered juice is directed to defecate.