HU176779B - Process for purifyng raw juice with intermediate alkalinating - Google Patents

Description

Procedure for purifying sugar factory juice by intermediate analysis

The present invention relates to a calcareous carbonated process for purifying sugar crude juice by adding lime milk to a slurry containing the precipitate of the first liming and carbonating, thereby increasing the adsorptive capacity of the precipitate and filtering it within a short time, thereby increasing the purification effect of the crude juice.

Sugar beet juice for the production of sugar consists of water and dry matter. From a technological point of view, the two main components of dry matter are sucrose, in short sugar, and all other dry substances in short, non-sugar. The purpose of sugar purification is to remove as many constituents of non-sugar as possible, since each non-sugar component makes it difficult to crystallize the sugar and reduces the amount of crystalline sugar that can be recovered. The refining of the sugar mill is effected by adding lime in the form of burnt lime or lime milk and by binding the excess lime with carbon dioxide and precipitating it in the form of calcium carbonate. Lime-carbon dioxide (carbonic acid) purity must meet two requirements:

1. Perfect removal of non-sugar materials by precipitation, coagulation, destruction and adsorption;

2. Removal of precipitate by filtration or settling or by settling and filtration as much as possible.

The two requirements are partly contradictory, and to the best of their ability, the modalities of current purification procedures have evolved.

One of the most well-known of these solutions is the long-established standard of purification introduced in Hungary between 1957 and 1961, based on Soviet and Czechoslovakian research and development work.

This classical process consists of the following technological operations5:

1. Progressive countercurrent pretreatment with lime milk, returning first aerated sludge juice to pre-digestion (temperature 85-90 ° C, hold time 4-8 minutes).

2. Main fermentation with lime milk (85-90 ° C, 5-15 minutes).

3. First carbonation in a continuous countercurrent system, pH ₂₀ = 10.7 to 11.0 with active alkalinity (84-88 ° C, 8-10 minutes).

4. Concentration of the first aerated precipitate by settling, to a volume of * / ₃ ^to ₄ of the original volume, or more recently, e.g. the so-called

with slurry filtration filters, '/ ₄ -' / j of the original volume.

5. Filtering the condensed precipitate - slurry - on a drum strainer, washing - sweetening - the juice filling the pores of the filtered sludge with water.

6. Second carbonation of filtered first carbonated juice until alkalinity removal of calcium and magnesium ions (lime salts) is most complete.

7. Filter the second carbonated sludge juice.

8. Feeding the filtered second carbonated juice into the pre - evaporator tank.

After the first (according to point 3) and the second (according to point 6) carbonation, the sludge broth is rested or cooled. stirred in (buffer) tanks in front of the pumps. The described process provided well-filterable and well-settled juices at a total lime consumption of 0.85-1.1 parts calculated on the non-sugar content of the juice, provided that the temperatures, preservative176779 digestion times and alkalis were observed. However, the removal of non-sugars was not extensive, mainly the adsorption was reduced. Microbial contamination of beet juice purification also caused filtration difficulties when the raw beet juice contained dextran, increased amounts of pectin or invert sugar. At the same time, the thermostability of the juice (apparently alkalinity) was greatly reduced.

Different solutions are used to eliminate these two disadvantages.

A} Enhanced Classic Life Purification with Cold Preflight

The so-called "point" described in point 1. hot preheating (85-90 ° C,

4 to 8 minutes), introducing cold progressive countercurrent pre-detection (40-65 ° C, 18-25 minutes) with first slurry instead of first mud slurry. The purified juice thus obtained is of higher purity and lighter due to better adsorption.

B) The so-called. Growing up on Sad

1. mixed with sludge from adsorption carbonic acid, "sensitized" (pH = 8, temperature 35-40 ° C).

2. Coagulation carbonization at 86 to 90 ° C in two reactors:

I. Simultaneous alkalization (with lime juice diluted with juice) and carbonation (with carbon dioxide gas) to pH 10.3 - 10.6 with active alkalinity.

II. circulating in a coagulating vessel.

I and II. The reactors are connected to large pipelines and the high-performance pump placed between them rotates the juice between the two reactors 8 to 10 times per minute.

3. Condensation of coagulated carbonated precipitate on sludge thickening filters.

4. Filtering and sweetening of coagulated slurry on drum filters.

5. Liming filtered juice after coagulation for 20 minutes.

6. Carbonation adsorption at 86-88 ° C, pH 10.5-11.0 for active alkalinity.

7. Sedimentation of the adsorption carbonated precipitate.

8. Introduction of adsorption slurry into sensitization.

9. Post-carbonation of adsorption carbonated filtered juice according to point 6 of the classical procedure ("second carbonation").

10th and 11th The classic second carbonated juice

7 and 8.

In many countries, there are procedures that follow these two directions. For direction A, the Brieghel-Müller (Danish) procedure, for direction B, e.g. RT method, these are not significantly different from those described.

A process for purifying sugar factory juice is described in U.S. Patent No. 3,834,911, which discloses that the juice obtained in the first aerated carbonation process is carbonated with ca. 0.065% CaO for alkalinity below titrated activity, and then alkalize (eg with lime milk) to normal alkalinity. The precipitate is then separated from existence and, instead of being used in pre-exploration due to its favorable properties, it is removed from the process.

A process for purifying already concentrated concentrated sugar juice or sugar refining solution is disclosed in US Patent No. 1902230, which purifies the juice or solution by cation and anion exchange, the concentration of salts containing highly dissociating anions, and the concentration of alkaline and alkaline earth ions in the solution. account.

Deferred Hungarian Patent Application H / 595, entitled "Procedure for Purifying Raw Beet Juice". The precipitate formed in the first carbonated acid is filtered off and removed from the process, and the precipitate which is concentrated in a known manner is prepared by adding lime and carbon dioxide to the pure brine obtained after filtering off the precipitate separated from the crude juice. Calcium hydroxide is then added and the resulting calcium carbonate-calcium hydroxide suspension is introduced into the pre-digestion.

The disadvantage of these known solutions is that they are demanding in terms of lime dosing, equipment and technological operations. These disadvantages of the known methods are overcome by the present invention, which is simpler than before, requires less equipment and technological operations, and produces a greater purification effect with less breeding.

The present invention is based on the discovery that calcium carbonate crystals are loosened on their surface in contact with calcium hydroxide in the presence of sucrose and that their adsorbing capacity is greatly increased. In the prior art, increasing the adsorptive capacity leads to a change in the texture of the crystalline precipitate such that its filtering and settling properties are severely impaired. In contrast, our research has shown that the change in the texture of the precipitate is much slower than the increase in adsorptive capacity. This discovery, hereinafter referred to as precipitation activation, is utilized by the present invention.

Advantages of the process according to the invention:

1. Activation of the precipitate formed in the first carbonic acid removes a significant amount of non-sugar material from the juice by adsorption, which is filtered off with the precipitate. This increases the purity of the juice, in particular, decreases the colloidal content, makes it lighter in color, increases its thermostability, reduces apparent alkalinity, and consequently speeds up the crystallization of sugar from dense juice, reduces the load on the crystallization equipment (sugar side), quality and increase in crystalline sugar yield.

2. The process is easy to implement with a small addition to existing equipment (pre-whey milk distributor, pH regulator) and is flexible to the improved classical purification operations, does not adversely affect precipitation filtration, and sometimes improves filterability.

3. Due to the advantages described in (1) and (2), the process of the present invention allows the acceptable purification of high non-sugar crude juices (machine picked, poorly cooked, over-fertilized beet juice or long extraction times), increasing the dose of lime milk. without.

4. The return of the active slurry thus obtained stabilizes the parameters of the life-cleaning system, making the system less sensitive to fluctuations in lime milk and better control of the whole teblological process.

The process of the present invention differs from any prior art process by adding calcium hydroxide (lime milk) to the first carbonated sludge broth before filtering and then directly filtering the sludge broth to produce activated sludge. This procedure is simpler than any procedure previously proposed for similar purposes, e.g. Növi Sad and RT.

The process of purifying a sugar factory crude juice by intermediate alkalization is that the precipitate formed in the first carbonation of the continuous countercurrent, preferably with a pH of 10.7 to 11.0 active alkaline (0.070-0.085% CaO titrated alkaline), is further 0.1-0. Is activated by the addition of 5% calcium oxide lime milk, and after 2-6 minutes, the first effervescent sludge juice is routinely transferred to a slurry filter, then the activated slurry is filtered and then 20-40% of the concentrate thus activated and without filtration, transfer a suitable proportion of the sludge slurry containing activated sludge to the cold progressive countercurrent pre-detection.

The process of the invention is illustrated by the following example, which is illustrated by the drawings of the purification process depicted in the accompanying drawings.

Preparation of active slurry:

A quantity of lime milk equivalent to 0.2% CaO per juice from the continuous countercurrent first carbonated effervescent vessel 4 is introduced before the juice enters the first sludge juice reservoir 5. The residence time of the sludge broths in the resting tank 5 is 2 to 4 minutes, with an average of 3 minutes depending on the tank size. During this time, lime milk activates a rich precipitate of calcium carbonate in the sludge broth. The cooling tank 5 also serves as a buffer tank in front of the pump. From there, the first sludge juice containing the activated precipitate is pumped into a pressure vessel 6 in front of the slurry concentrator 7, where the residence time of the juice is 1 ± 0.5 minutes. The juice is transferred from this pressure vessel 6 to the sludge thickener filter 7, from which about 75% flows as filtered juice through the heater 11 to the second carbonator 12. 25% of the precipitate is activated sludge, which flows into the first sludge tank 8, from where it is pumped to the first sludge distribution tank 9. From here, about 60-75% of the slurry goes to the drum filters 10, where it is filtered and the juice is squeezed out of the sludge layer with water, the sugar is sweetened and transported from the plant to the sludge field. About 23-38% of the activated slurry flows from the same first slurry distribution vessel 9 to the penultimate section of the countercurrent progressive preflight 1. Activated slurry should be approx. 2% of it flows into the second sludge container 16 after the second carbonation, where it is activated by the second sludge and the slurries thus mixed are fed into the raw beet juice in the pre-scavenger 1. The purification process from raw juice to ginger in our example is as follows:

The raw juice from the extraction of the sugar beet is pumped into the pre-digester 1. Before entering the pre-detector 1, the activated second slurry pumped from the tank of the second slurry 16 is stirred. Pre-detection in a progressive countercurrent system at 45-50 ° C for 20-22 minutes. We pass the first activated slurry to the penultimate stage after the entry of the juice. To obtain optimal alkalinity for pre-digestion, the proportion of lime milk from the lime feed portion to the pre-digester and slurry activation is adjusted to adjust the pH from 11.2 to 11.4 pH ₂₀ (0.25-0.35% CaO). The pre-clarified juice is heated to 86-88 ° C on the heater 2 and fed to the main clarifier 3, where the lime milk signal corresponding to 1.6-1.8% CaO per juice is mixed for approx. for 10 minutes. From here, the juice flows into the first 4 carbonated foamers, where the lime juice is neutralized with carbon dioxide-containing lime kiln throat gas to a titrated alkalinity of 0.07-0.09% CaO. The resulting calcium carbonate-rich sludge slurry is treated with 0.2% CaO in lime milk before being introduced into the resting tank 5 (buffer tank). The latter is distributed proportionally from the liming portion of the lime feed dispenser to the first carbonated sludge slurry through the appropriate line to the cooling vessel 5. The sludge slurry containing the activated sludge from the leaching tank 5 is pumped through the pressure vessel 6 into the first slurry filter 7 via a pump containing sludge activated with lime milk. The juice is approx. Activated slurry, 25% of which, passes through the aforementioned paths to the first slurry carrier 8 and first slurry distributor 9 to the drum filter 10 and the pre-detector 1 respectively. The filtered juice from the drum filter 10, together with the filtered juice from the slurry thickener 7, is pumped through the all heater into the second hydrocarbon reactor 12 while heating to 98-101 ° C. The second acidic acidification is similar to the first, up to a titrated alkalinity of 0.018-0.022% CaO, more precisely the optimal alkalinity determined by laboratory testing. The second sludge slurry is then transferred to the precipitation matrix 13 and then through the pressure vessel 14 to the sludge thickening filters 15. From here, about 95% of the juice is filtered juice, which is discharged into pre-evaporator ice containers. Approx. 5% slurry, mixed with 2% active slurry, is pumped into the crude juice before entering pre-exploration.

The total purification process described in this example differs from the improved classical process (cold pre-skimming) in that the portion of lime milk for the pre-whey is properly distributed between the first sludge slurry and pre-skim using a simple lime milk divider. A significant proportion of the activated sludge obtained from the lime milk activated sludge slurry is fed to the penultimate section of the pre-scavenger 1, and a small proportion is mixed with the second sludge into the raw juice. This relatively simple modification achieves the technological and economic benefits described herein. The procedure described in this example is simpler, easier to control, and requires less equipment than the methods previously used to enhance the effects of purification (e.g., Növi Sadi or RT).

Claims (2)

Patent claims A process for purifying a sugar mill crude juice by intermediate alkalization, wherein the progressive countercurrent pre-digestion with active slurry or possibly lime milk, the primary decarburization with lime milk, the first carbonation in a continuous countercurrent system, characterized in that the —The precipitate formed in brine with 11.0 active alkalinity (0.070-0.085% CaO titrated alkalinity) is added by adding an additional 0.1-0.5% calcium oxide lime milk, and after 2-4 minutes, the first carbonated sludge slurry is applied to the slurry thickener as usual. followed by filtration of the activated slurry, followed by 20-40% of the activated slurry of the condensed slurry or an appropriate proportion of the sludge slurry containing the activated slurry without filtration, into the cold progressive countercurrent preflighting. 5 2. The process of claim 1, wherein 1-5% of the activated slurry is mixed with the slurry filtered from the second aerated juice, the second activated slurry thus being mixed with the crude juice prior to de-frosting. 1 drawing, 1 figure Sponsored by KSacnteategi te Jtetí KSeyvkwdb ifeagfitta