KR970006318B1 - Freeze concentration system and method - Google Patents

Abstract

None.

Description

Freeze Concentration System and Method

1 is a layout view of one embodiment of a two stage countercurrent freeze concentration system in accordance with the present invention.

2 is a cross-sectional view of the first stage gradient column of the FIG. 1 freeze concentration system.

3 is a cross-sectional plan view taken along line 3-3 of FIG.

4 is a partial cross-sectional view of another embodiment of a two stage countercurrent freeze concentration system in accordance with the present invention.

5 is a partial cross-sectional view of a single stage freeze concentration system embodying the principles of the present invention.

6 is a cross-sectional view of another embodiment of a gradient column of the present invention.

* Explanation of symbols for main parts of the drawings

10: first concentration step 12: second concentration step

14: feed solution recycle circuit 16: intermediate concentrate recycle circuit

18: concentrate recirculation circuit 20: first step gradient column

21, 23: determinant 22: second stage of inclined column

24 series filter 25 washing column

26: feeding tank 27, 29: cooling unit

28: surge tank 30: heating unit

40: cylindrical cell 41: filter screen

44: scraper blade 45, 50: rotation axis

46: ice layer (ice layer) 47: rotating disc

60: single unit (two stage system) in which the first stage gradient column 20 and the washing column 25 are combined

71: single unit (stage system) in which the gradient column 20 and the washing column 25 are combined

81: cylindrical cell 82: cylindrical filter

The present invention relates to a continuous countercurrent system and method for freeze concentration of aqueous solutions. More specifically, the present invention relates to freeze concentration of edible aqueous solutions such as fruit juices, extracts that can be dissolved in coffee and cold water, milk, wine, beer, vinegar, and the like. Ice crystals) use advanced systems and methods that facilitate the removal of liquids covered by ice crystals and promote the growth of ice crystals in the system.

The freeze-concentration process is based on the principle that ice crystals formed by cooling an aqueous solution to its freezing point exclude dissolved solutes, since they make ice crystals of pure water into a more concentrated liquid. Freeze concentrations are used in many commercial means, such as those that require the recovery of ice crystals as a product of processes such as seawater desalination, industrial waste treatment and other pure water production. As a product of a process such as concentrating a solution or suspension containing food products such as coffee or tea extracts, citrus juices, fruit juices, milk, wine, beer, vinegar, etc., both of which require the recovery of the concentrated liquid from the ice crystals. to be.

Although the required product is an ice crystal or a concentrated liquid, freeze concentration basically consists of cooling until the water is all frozen in the form of ice crystals, separating the ice crystals thus formed from the concentrated liquid as a result, liquid covered with crystals. Removal of the ice crystals from the system. In a continuous freeze concentration process, the solution to be concentrated becomes more and more concentrated over several cycles or steps, and continues until the concentration is required. Since the ice crystals become progressively more concentrated solutions, the more concentrated solutions are more viscous and therefore more difficult to remove from the ice crystals. Moreover, the growth rate of ice crystals is inversely related to the concentration of the liquid surrounding them, so that the ice crystals produced are relatively small when the liquid concentration is relatively high. This adds to the difficulty of removing the liquid from the ice crystal, since it is more difficult to remove the liquid covered by the smaller crystals than the larger crystals.

Removal of liquids adhering to ice crystals is a critical step in the effective implementation of all freeze concentration processes. In general, an effective means of removing the liquid attached to the ice crystals is a washing column in which the packed layer of ice crystals is washed with water to remove the liquid covered by the ice crystals. The efficiency of the washing column is inversely proportional to the viscosity of the liquid attached and is directly proportional to the square of the effective crystal diameter. It is therefore desirable to lower the viscosity of the liquid surrounding the ice crystals in order to facilitate the removal of the covered liquid from the crystals. One process that has been used so far to achieve this is to introduce a solution to be concentrated between the crystallizer where the ice crystals are formed and the wash column where the ice crystals are purified to generate a countercurrent flow of solution and ice crystals in the system.

There are many publications in the prior art that belong to the countercurrent flow of liquid and ice crystals in such freeze concentration systems. For example, in September 1973, Thyssen, HAC, presented at a symposium on developments in dehydration and preconcentration at the International Union of Food Science and Technology, Sheldon Park, UK. In the paper Freeze Concentration, the principle of countercurrent flow of liquid and ice crystals in a freeze condensation system is presented and the benefits obtained by adopting fluid feeding between the crystallization and the washing column are described. Similarly, U.S. Pat.Nos. 2,540,977 (Arnold), 3,402,047 (Shaul), 3,681,932 (Huber et al.), 4,338,109 and 4,332,140 (Tieb Thijssen et al.), 4,406,679 (Robel Wrobel et al.) 4,557,741 (Banfel) Van Pelt), each of whom announces a freeze-freezing process that uses several variations of freezing point and countercurrent flow of liquids. However, each of these conventional systems and processes suffers one or more disadvantages in commercial practice that adversely affect their efficiency and efficiency.

The present invention provides a continuous countercurrent freeze concentration system and method that effectively reduces the viscosity around the ice crystals formed in the system, thereby facilitating removal of liquid covered on the ice crystal surface and promoting the growth rate of the ice crystals. In the present invention, the concentrated aqueous solution is subjected to one or more concentration steps, each concentration step is a liquid recycling circuit in which the crystals combined with the gradient column and the liquid discharged from the gradient column circulate through the crystal phase and return to the gradient column Has The ice crystallizes from the liquid in the crystallizer at each stage, whereby the concentration of the liquid is increased, and the ice formed at each stage is directed to the gradient column of that stage and moved in the opposite direction to the flow of liquid to be concentrated. Thus, the ice crystals produced in the crystallizers of each stage are separated from the liquid and formed into ice crystal masses of the porous moving bed in the gradient column of each stage. The liquid covered by the crystal surface in the ice layer is replaced by the countercurrent flow of the thinner liquid. Ice crystals covered with thinner liquid are discharged from the ice layer and transferred to the thinner liquid circulated in the previous crystallite or wash column. Although the present invention may be practiced in single or multiple stage systems, implementation in conventional two stage systems is employed.

The adopted two-stage system utilizes two concentration stages, with two gradient columns (each of which forms ice crystal masses of porous moving bed) and a crystallization column and a single wash column connected to each gradient column. Liquid recirculation circuits are provided to circulate the liquid through the crystallites of each concentration stage and also to circulate between the first stage and the washing column. Typically the feeding liquid having a solid concentration of about 2-20%, i.e. the aqueous solution to be concentrated, is concentrated to yield a medium concentration of liquid (i.e. 10-30% solids) in the first concentration step and in the second concentration step Concentrate to yield Heavy Liguid (36-50% solids). The heavy liquid portion is discharged as a product in the second concentration step.

Ice crystals are made in crystallizers connected to each stage. The ice produced in the second stage is covered with concentrated liquid or heavy liquid.

This ice slurry in the heavy liquid is guided to a second stage gradient column, whereby the ice portion of the slurry is formed into a porous ice crystal mass, which rises countercurrent to the flow of the intermediate concentrate through the gradient column and the intermediate concentrate is first Filtration in a step gradient column permeates the ice bed. The heavy liquid adhering to the ice crystal surface of the ice layer in the second stage gradient column is replaced by the countercurrent flow of the intermediate concentrate as the ice layer rises through the column. The liquid portion of the slurry is returned to the second stage crystallizer, while the ice replaced with the heavy liquid is separated from the ice layer in the second stage gradient column and transferred to the intermediate concentrate. This slurry is directed to the first stage determinant where additional ice is formed. The slurry of ice and intermediate concentrate from the first stage crystallizer is directed to the first slope column. The ice portion of the slurry, covered with the intermediate concentrate, is formed as a layer of permeable ice crystal mass which flows back through the first stage gradient column and flows back to the flow of the feed concentrate. The liquid portion of the slurry guided to the first stage gradient column is separated from the ice and guided to the second stage gradient column, where it is used to displace the heavy liquid covered by the ice crystals of the ice layer and to transfer the ice crystals from the ice layer to the first stage crystallizer. do. In the first stage gradient column, the intermediate concentrate covered with ice crystals is replaced by the countercurrent flow of the feed concentrate. Ice crystals in which the intermediate concentrate is replaced by the feed concentrate are transferred to the feed concentrate, which is separated from the ice layer and guided to the washing column, where the bed pressure and growth period are involved, and the covered feed concentrate is replaced by ice with clean water, and then the feed concentrate Is recycled to the first stage gradient column.

The present invention is particularly suitable for a freeze-concentration process in which an increase in concentration of the dilute solution is required to recover the concentrated stock solution as a product. In other words, fruit juice, tea extracts that can be dissolved in coffee and cold water, milk, beer, wine, vinegar and concentrate. The invention is also suitable for a freeze-concentration process that requires the recovery of pure water as a product. That is, desalination of seawater and purification of industrial wastes.

The freeze concentration system and method of the present invention provide notable advantages over prior art systems and methods. The present invention provides efficient substitution of heavy and intermediate concentrates in ice crystals and promotes the growth of relatively large ice crystals in a short period of time. The period required for crystal growth is consequently reduced because crystal growth occurs in rapid concentration. Because of the relatively large ice crystals, the large capacity of the wash column facilitates efficient washing of the ice, which in turn reduces much solute loss in the system.

Figure 1 schematically illustrates the countercurrent freeze concentration system of the present invention with two concentration steps, both of which are represented generically as 10 and 12, both with gradient columns and crystallizers. It will be appreciated that the present invention may be used with only a single concentration step or as a further concentration step if necessary or justified to achieve the required concentration. The aqueous solution to be concentrated (or recovering water therefrom) enters the system at A and is circulated throughout the system by three recycle circuits. The three recirculation circuits here comprise a feed solution recycling circuit 14 which circulates the feed concentrate between the first concentration stage 10 and the washing column 25, and an intermediate for circulating the liquid around the determinant of the first concentration stage. A concentrate recycle circuit 16 and a concentrate recycle circuit 18 for circulating the concentrate, ie, the heavy liquid, around the crystallizer of the second concentrate stage.

The first concentration step 10 has a crystallizer 21 for making an ice slurry from the intermediate concentrate, and a first stage gradient column 20 into which the intermediate concentrate slurry made from the crystallizer 21 is pumped. In the first stage gradient column 20, the ice portion of the slurry is separated from the liquid and the ice crystals are formed into permeable ice crystal masses. The intermediate concentrate covered with ice crystals is replaced by the feed liquid backflow flow introduced from the feed liquid recycle circuit 14, and the ice is discharged from the permeable layer and recirculated in the recycle circuit 14 for introduction into the washing column 25. It is moved to the feeding liquid in circulation. The second concentration stage has a crystallizer 23 for making an ice slurry from a concentrate, that is, a heavy liquid, and a second stage gradient column 22 to which a heavy liquid slurry made from the crystallizer 23 is supplied. In the second stage gradient column 22, the ice portion of the slurry is separated from the heavy liquid, and the ice crystal is formed into a layer of permeable ice crystal mass. The heavy liquid covered by the ice crystals is stripped off and replaced by the countercurrent flow of the intermediate concentrate supplied from the intermediate concentrate recycle circuit 16. Ice crystals covered with the intermediate concentrate are discharged from the permeable layer and moved to the intermediate concentrate circulating in the recirculation circuit 16 and are also conveyed to the first stage determiner 21.

The heavy liquid portion discharged from the second stage gradient column 22 enters the recycle circuit 18, passes through the second stage determiner 23 and is introduced back into the column 22. In-line filter 24 is a downstream provided in crystallizer 23 to withdraw a portion of the concentrate from system B in B.

Determiners 21 and 23 are both configured as conventional scraped surface heat exchangers, where the heat exchanger is adapted to pass refrigerant through an outer jacket for efficient cooling of the liquid therethrough. Accompanied by an apparatus (not shown). Sufficient refrigerant is circulated through the jacket to freeze a predetermined amount of ice crystal from the liquid passing through the crystallizer. For example, the second stage determiner 23 cools the liquid in the recirculation circuit 18 to freeze enough ice to provide a solids concentration between about 36-50% and preferably 40-50% of the liquid passing therethrough. Increase to The first stage determiner 21 cools the liquid in the recycle circuit 16 to freeze enough ice to raise the solids concentration of the liquid to between about 10-30%, preferably between 20-25%. If desired, conventional scraping heat exchangers connected in series or in parallel may be used in place of the single crystals 21 and 23 shown in FIG. 1 in both the first and second concentration steps. Other types of crystallizers or chillers may be used to cool the liquid to the desired range.

An aqueous solution to be concentrated, that is, an aqueous solution having a solids content of about 2 to 20%, is supplied to the feeding tank 26 in A, and the surge tank is passed through a cooling unit 27 in which the feeding liquid is first cooled in the feeding tank 26. Pumped into 28, enters the feed liquid recycle circuit 14 in the surge tank 28 and combines with the feed liquid separated from the wash column. The combined feed liquid is transferred to the line 51 via the cooling unit 29, in which the liquid is cooled to some point, and introduced into the top of the first stage gradient column 20. The cooling units 27 and 29 can each be configured with conventional scraping heat exchangers, which involve an apparatus (not shown) for passing the refrigerant through an outer jacket to cool the liquid to the required range. Of course, other suitable cooling devices may be used to cool the feed liquid to its freezing point.

Most of the feed liquid introduced into the gradient column 20 remains in the feed liquid recycle circuit 14. That is, the feed liquid is transferred from the inlet line 51 through the top of the column 20 to the discharge line 52 and the washing column 25, and moves the ice discharged from the permeable ice layer in the column 20 to the washing column. It plays a role. A small portion of the feed liquid introduced into the gradient column 20 (corresponding to the concentration and the amount of washed ice recovered from B and C from the system, respectively) flows back into the layer of permeable ice crystals coming up in the gradient column. Pass down. Here, the ice crystal mass layer is formed in the gradient column 20 from the ice slurry of the intermediate concentrate calculated by the first stage crystallizer 21. Thus, the slurry of intermediate concentrate and ice (from both the first and second stage determinants 21 and 23), which typically has an ice weight of less than about 25%, passes through the line 42 to the gradient column ( 20) is introduced into the bottom. The liquid portion of this slurry is separated from the ice portion and discharged from the gradient column 20 via line 43. The ice portion of the slurry is covered with an intermediate concentrate and formed into a loosely compressed permeable ice layer that rises in column 20. As the countercurrent flow of the feed liquid passes through the ascending ice layer, the cohesive intermediate concentrate covered by the ice crystals is stripped off and replaced instead. The replacement of the freeze-covered intermediate concentrate with the feed solution takes place in the lower ice layer, typically the lower third of the ice layer, in the gradient column 20, so that the ice crystals in the feed liquid are significantly above the substantial part of the ice layer. Enable growth. As the ice layer rises through the column, the ice crystals covered with the feed liquid are separated from the top of the ice layer, such as by scraping or cutting, and then moved to the feed liquid portion circulating in the recirculation circuit 14, which is the recirculation circuit. The ice slurry in the resulting feed is transferred from column 20 to the wash column.

The feed liquid portion that penetrated through the permeable ice layer in the column 20 and the intermediate concentrate peeled off from the ice layer were combined with the intermediate concentrate portion separated from the slurry introduced into the bottom of the column 20 to the recirculation circuit 16. It enters and is moved from the first gradient column 20 to the top of the second gradient column 22 via the line 43. The concentration of intermediate concentrate separated from the slurry introduced at line 42 is slightly reduced by mixing with the remaining portion of the feed liquid. However, by controlling the porosity of the ice layer, the amount of feed liquid passing through the ice layer, as discussed below, is about 4%, preferably 1 to 3% (absolute) at most to the concentration of the intermediate concentrate introduced in line 42. Decrease only). The combined liquid stream introduced via line 43 to the second stage gradient column 22 is still of medium concentration.

The function and operation of the second stage gradient column 22 is the same as the first stage column 20, except that the intermediate concentrate is used to strip off and replace the heavy liquid covered by the freezing point in the rising permeable ice layer. . Thus, most of the intermediate concentrate introduced into the column 22 remains in the recirculation circuit 16, from the inlet line 43 through the line 54 across the top of the column 22 to the determinator 21 and the first stage. Is transferred to the gradient column 20 and serves to move ice from the second stage gradient column 22 to the first stage column. Most of the intermediate concentrate introduced into column 22 (which is equal to the amount of concentrate recovered from the system in B and the amount of ice introduced into column 22) is the ice slurry in the heavy liquid produced in the second stage determiner 23. Flows downward in the column 22 from countercurrent to the rise of the permeable ice crystal mass formed in the gradient column 22. The slurry of the heavy liquid and the ice, typically having a weight of less than 25%, is made in the crystallizer 23 and introduced into the bottom of the second stage column 22 via line 53. The heavy liquid portion of this slurry is separated from the ice portion and discharged from the column 22 via the line 55. The ice portion of the slurry is formed of a permeable ice layer which is covered with a heavy liquid and rises through the column. Downflow of the intermediate concentrate through the rising ice layer strips off and replaces the viscous heavy liquid covered by the ice crystal, which is replaced at the bottom of the column, thereby promoting the growth of the ice crystal in the low viscosity intermediate concentrate. do. As the permeable ice layer rises through the column, the ice crystal is covered with the intermediate concentrate, separated at the top of the ice layer in the second stage gradient column 22, and moved to the portion of the intermediate concentrate circulating in the recycle circuit 16. The resulting slurry is transferred from the column 22 to the first stage crystallizer 21, where additional ice is crystallized out of the liquid and the concentration of the liquid is slightly increased, and then is transferred to the first stage gradient column 20. . The middle concentrate portion passing through the permeable ice layer in the gradient column 22 and the heavy liquid stripped from the ice layer enter the circuit 18 in combination with the heavy liquid portion separated from the slurry introduced into the bottom of the column 22, which is determined by Circulation through 23) returns to column 22. The amount of intermediate concentrate combined with the heavy liquid thus controls the permeability of the layer, so that the concentration of the heavy liquid is at most about 10% at most and at most about 6% when the ice portion of the slurry in line 53 is below 25% by weight. Baseline). The liquid circulated through the second stage determiner 23 is cooled to crystallize enough ice to increase to the extent required for the solids content of the liquid, typically between about 36% and 50%. And the ice slurry in the concentrate passes through an in-line filter 24, where the concentrate portion exits the system at B as a product, and the remaining portion of the slurry typically has an ice portion of about 10% to 25% by weight, Through 53 it is moved to the bottom of the second stage gradient column 22.

Ice slurry in the feed liquid discharged from the top of the first stage gradient column via line 52 is introduced into the washing column 25. Ice crystals in the washing column are compressed and raised by recycling the feed liquid in the recycling circuit 14. The feed liquid flows upward through the compressed ice bed and is discharged from the bed through the side screen 31 and transferred to the surge tank 28 via the line 32. Significant ice crystal growth occurs at the bottom of the wash column, ie up to the liquid level on the side screens. As the compressed ice layer moves over the side screen, the ice covered feed is replaced by a downward flow of clean water introduced through the line 34 to the top of the wash column. Clean ice rises to the top of the wash column, and ice is scraped off the layer by conventional means, transported via line 33 to heating unit 30 and melted there. The melted ice portion is circulated in line 34 to the top of the wash column for use as wash water. Molten ice that is not used for cleaning is discharged from the system at C.

As described so far, ice crystal growth in the system occurs to a significant extent not only at the top of the first stage gradient column but also at the bottom of the wash column, resulting in ice crystals that can exceed 200 microns in size, resulting in only about 0.01 ice crystals. It has a purity in which covered solids are present between% and 0.1%.

The system of the present invention, of course, entails additional conventional accessory devices such as valves, motors, pumps, and the like, but is not shown or described herein for the sake of clarity.

The use of such conventional accessory devices in the present invention is already apparent to those skilled in the art.

The first stage gradient column 20 is shown in more detail in FIG. As shown in FIG. 2, the inclined column 20 consists of a cylindrical shell 40 whose top and bottom are blocked by flat plates 56 and 57, respectively. The filter screen 41 is employed to separate the ice portion of the slurry from the liquid portion, and may be of any suitable type, such as a wire mesh screen, a perforated metal plate, a perforated member supporting the filter cloth, or the like. . The filter screen preferably has holes between about 0.15 mm and 0.30 mm in size to facilitate separation of the slurry parts. The ice crystal slurry in the intermediate concentrate calculated by the first stage determiner 21 is pumped through the pipe 42 under pressure to be sprayed onto the upper surface of the filter screen 41, and the liquid portion of the slurry is passed down through the screen. It descends and is conveyed through the line 43 from the first step ramp column 20 and introduced into the top of the second step ramp column 22. The scraper blade 44 is mounted on the rotational shaft 45 just above the upper surface of the filter screen 41 to keep the screen relatively free of ice. The shaft 45 is rotated by a conventional motor device (not shown). The deposited ice crystals (covered with intermediate concentrate) of the screen 41 are maintained in the column 20 by the continuous introduction of fresh ice in the slurry pumped from the crystallizer 21 and the role of the rotary scraper blade 44. Is moved upward. The rotating plate 47 has one or more openings extending therethrough and is mounted transversely to the column 20 in proximity to the top plate 56 to alter the cross section of the column to inhibit and control the upward movement of the ice crystals. It is firmly covered. Crystals are formed into agglomerates by upward movement of the ice crystals in the column, so that the agglomerated ice crystals are formed into the infiltration layer 46 and rise in the column 20 due to the ice introduced further through the line 42. do. As shown in more detail in FIG. 3, the disc 47 has a lower surface such as scraping or cutting means, such as cutting edges 49, for scraping or cutting ice at the top of the ice layer. Thus, the ice is discharged continuously from the ice layer. The disc 47 has an opening 48 of sufficient size and quantity that penetrates through so that the ice scraped from the top of the ice layer rises up through the plate, and the feed liquid flows downwards through the disc toward the ice layer. Allow. Other suitable means for inhibiting and controlling the ice layer may be used. For example, there is a metal plate, such as one having a plurality of openings and attaching a cutting device to the bottom surface thereof, or a developed metal screen disc having openings close to about 0.2 to 4 cm in size. The disc 47 is mounted on the shaft 50 and rotates the shaft 50 and the disc 47 at the required speed and is independent of the rotation of the scraper blade 44, for example at or at the same speed or opposite. It rotates by the normal motor apparatus which rotates to a direction.

The cooled feed liquid is delivered to the column 20 from one place on the rotating disc 47 via an inlet pipe 51, and a discharge pipe 52 is provided at the opposite edge of the upper plate. Most of the feeding liquid introduced into the inclined column 20 through the pipe 51 circulates on the disc 47, and serves to convey the ice manipulations scraped from the upper portion of the ice layer through the pipe line 52 to the washing column. Do it. The remainder of the feed liquid flows back down to the ascending ice layer via the opening 48 in the disc 47. This feed portion completely penetrates the permeable ice layer and replaces the intermediate concentrate covered with ice crystals. Substitution of the more viscous midconcentrate by the less viscous feed liquid occurs at the lower part of the ice layer, typically one third below the bed, and in the feed liquid covered by it, a significant ice crystal outperforms the substantial part of the ice layer. Growth is promoted. The feed liquid that has passed through the ice layer is passed through the filter screen 41 and combined with the portion of the concentrate concentrated in the slurry pumped from the recycle circuit 16 to the gradient column 20, and the combined liquid (still in medium concentration). Is discharged from the column 20 through line 43.

The degree of compression of the ice layer 46 is suppressed in order to facilitate the effective replacement of the intermediate concentrate covered with ice crystals with the feeding concentration liquid. That is, the degree of compression of the ice crystal mass is controlled to provide an ice layer having sufficient permeability to allow the countercurrent flow of the feed liquid to pass through all the ice crystal mass layers without excessive pressure drop. The more compacted ice bed has a limited flow of feed liquid through the bed therein, which is much more effective in avoiding back mixing of the feed and intermediate concentrates and replacing the intermediate concentrates in the ice. Such more compacted beds are generally undesirable because they reduce the liquid flow through the ice bed and consequently reduce the capacity of the system or otherwise require a large pressure drop for the same capacity. However, the ice bed must be sufficiently compressed to prevent or minimize the drift of the feed through the ice bed. Drifting of the feed liquid causes undesirable back mixing of the feed liquid and the intermediate concentrate, resulting in too low a concentration of the intermediate concentrate in the line 43. The ice layer must be sufficiently compressed so that the amount of feed through the ice layer is approximately equal to the amount of concentrated ice recovered from the system and the washed ice, so that the intermediate concentrate introduced via line 42 has a concentration of line 42. When the ice portion of the slurry in the slurry is less than 25%, it is reduced by at most about 4% (absolute basis). In other words, the concentration of the liquid discharged from the inclined column to the line 43 may be only about 4% lower than the liquid reaction concentration of the slurry introduced into the inclined column in the line 42. If the bed is not compact enough, the feed will drift the bed, resulting in a significant backmixing of the feed and the intermediate concentrate, which adversely affects the replacement of the concentration in the ice and increases the concentration of the feed (then Promotion of crystal growth is not satisfactory). Moreover, the intermediate concentrate in line 42 dilutes to an undesirable range when the layers are not sufficiently concentrated. The degree of compression of the ice layer is preferably adjusted by changing the rotational speed of the disc 47 and varying the rate of ice discharge from the layer. Thus, lowering the rotational speed of the disc 43 decreases the ice removed from the top of the ice layer 46 and thus increases the compression of the layer, while increasing the rotational speed increases the discharge of ice and lowers the degree of compression of the layer. The ice discharge rate required to maintain the desired degree of compaction of the ice bed is dependent upon factors such as the rate of slurry introduction into the column 20, the amount of slurry ice, the rate of feed into the column, the system capacity, the size of the ice bed, and the like. It can be determined by one skilled in the art. For example, satisfactory operating efficiency can be obtained when the ice layer in the oblique column has a height to diameter ratio of between about 0.5: 1 to 3: 1 or more.

The second stage gradient column 22 is similar in structure to the first stage column 20 and has all the elements described above in relation to the column 20. In the second stage inclined column 22, ice crystals covered with heavy liquids produced by the crystallizer 23 in the second stage column are formed as permeable ice crystal mass layers, and the heavy liquids covering the ice crystals are in the intermediate concentrate circulated in the recycle circuit 16. It is similar to the function of the first stage oblique column, except that it is peeled off and replaced by. The degree of compression of the ice layer in the two-stage gradient column 22 is controlled in the manner described above with respect to the ice layer 46, although the amount of intermediate concentrate passing through the ice layer is dependent on the amount of concentrate recovered in the system. The ice layer is compressed to be approximately equal to the amount of ice introduced.

The layer compression is such that when the ice portion of the slurry in the line 53 is 20% or less, the heavy liquid concentration in the line 53 is reduced by at least about 10% (absolute basis) by the intermediate concentrate having passed through the bed. The crystals removed from the top of the ice layer in the second stage gradient column are covered with intermediate concentrate, are transferred to the intermediate concentrate portion circulating in the recycle circuit 16, and are carried through the crystallizer 21 to be transferred to the first gradient column ( 20) is introduced into the bottom.

4 illustrates another embodiment of the stage freeze concentration system of the present invention, wherein the first stage gradient column 20 and the washing column 25 are combined as a single unit and are denoted 60 inclusive. In all other respects the system shown in FIG. 4 has a structure and operation similar to that described in FIG. For the sake of clarity, the same parts are denoted by the same reference numerals. The system thus involves two warp columns 20 and 22, a determinant 21 connected to each warp column, 23 and a single wash column 25.

The feeding liquid (2% to 20% solids) is concentrated in the first stage to medium concentrations (10% to 30% solids) and in the second stage to medium liquid concentrations (36% to 50% solids), and the heavy liquid portion is the product. Is recovered from B. The first stage warp column and wash column are combined in a single unit, but still function in the same function, in the same way as described in FIG. That is, the slurry of the intermediate concentrate and the ice is pumped from the crystallizer 21 to the upper surface of the screen 41 in the gradient column 20, where the ice portion of the slurry (covered with the intermediate concentrate) is formed into a permeable ice crystal layer. Up through the slope column. The feed liquid enters the system from A, cools to some point in the cooling unit 29, enters the feed liquid recirculation circuit 14, and is opened in the middle of the bottom of the rotating disc 47 and the bottom of the washing column 25. It is introduced into (60). As depicted in FIG. 1, the feed liquid portion oozes down through the permeable ice layer 46 as the ice layer rises and replaces the intermediate concentrate covered with ice. The ice crystal covered with the feeding liquid is discharged from the upper portion of the ice layer 46 by the rotation of the disc 47, and is moved to the feeding liquid circulating in the recirculation circuit 14. The resulting ice slurry in the feed liquid is conveyed to the washing column 25 of the unit 60 where the ice crystals are compressed and subjected to the recycling of the feeding liquid between the washing column, the surge tank 28 and the gradient column 20. Rises by. The feeding liquid flows upward through the compressed ice layer in the washing column 25 and is discharged through the side screen 31. The clean ice is scraped from the top of the ice layer in the washing column and moved along the line 33 to the heating unit 30, where the melted ice portion is discharged at C. The feed liquid penetrating through the permeable ice layer 46 in the gradient column 20 is combined with the intermediate concentrate portion separated from the slurry introduced to the bottom of the column 20 and passes through the line 43 to the second step. It is moved to the top of the gradient column 22 and functions in the same manner as described above with respect to FIG.

5 shows a single stage freeze concentration system embodying the present invention. The system is similar to that of FIG. 4, in which the oblique column 20 and the washing column 25 are combined (indicated by 71 inclusive) in a single unit. However, it has been modified to have only one concentration step, that is, the gradient column 20 and the associated determinant 21. Elements of FIG. 5 that are the same as those of FIG. 1 are given the same reference numerals. The structure and function of the gradient column 20 and the cleaning column 25 of FIG. 5 are the same as those shown in FIG. The filtered liquid through the filter screen 41 adjacent to the bottom of the unit 71 is conveyed via line 74 to one or more scraping heat exchangers connected in series or in parallel, where the heat exchanger cools the liquid and concentrates, eg For example, freeze enough ice to make an ice slurry in a solid content of at least 36%. The resulting slurry exits the system from the system at B through a series filter 24. The remaining slurry is introduced to the bottom of the inclined column 20 via the line 42, and the ice portion of the slurry is formed into a permeable ice crystal mass layer and ascends through the inclined column, in which the ice-covered concentrate concentrates the line 51. It is replaced by a cooled feed liquid introduced into the unit 71 at a position halfway between the rotating disc 47 and the bottom of the washing column 25. Ice crystals covered with the feed liquid are separated from the upper portion of the ice layer 46 by the disc 47 and enter the feed liquid entering through the line 51 via the disc. The ice crystal thus separated is conveyed to the washing column portion 25 of the unit 71 relative to the feeding liquid.

6 shows another embodiment of a gradient column suitable for use in the freeze concentration system of the present invention. The inclined column (indicated by 80 as a whole) has a cylindrical cell 81 whose top and bottom are blocked by a lid 82 and a bottom lid 83. In this embodiment, the cylindrical filter 84 is such as a wire mesh screen, a perforated metal cylinder, or the like, and is used to separate the ice portion from the liquid portion in the slurry pumped through the inlet pipe 85 to the bottom of the inclined column. The liquid portion flows upward along the filter 84 and enters the annular chamber 86 provided between the filter and the cylindrical cell 81, where it is discharged along the pipeline 87. The freezing portion of the slurry is moved upward by the continuous introduction of the slurry through the pipe 85 and the rotation of the blade 88 mounted adjacent to the column bottom. The blade 88 is attached to the rotating shaft 89 and continues to rotate by the normal motor device 90. The rotatable perforated disc 91 is mounted on the shaft 89 on the upper end of the filter 84 and suppresses and controls the upward movement of the ice crystals in the column, thereby allowing the ice crystals deposited in the column to penetrate the permeable ice crystal mass layer. 92). Dilute liquid is introduced into the column above the ice layer via line 93 so that some of the dilute liquid descends through the permeable ice layer that rises through the opening 94 in the disc 91 and is more concentrated in the ice crystals. Peel off and replace the liquid. The concentrated liquid replaced in the ice crystal is discharged via the line 84 through the filter 84, with some dilute solution. The ice covered with the dilute solution is separated from the top of the ice layer by the rotation of the disc 91 and passes through the opening 94 to the dilute solution portion on the disc 91, and the resulting slurry is passed through the outlet 95. Leaving the column.

The following Examples 1-3 describe variables for the implementation of the two-stage system shown and described in FIG. 1, and Example 4 relates to the implementation of the single-stage system shown and described in FIG. All examples are based on freeze concentration of water soluble coffee extracts, wherein the height-to-diameter ratio of the permeable ice layer is between 0.5: 1 and 3: 1.

Of course, aqueous solutions other than coffee extracts, such as fruit juices, tea extracts that can be dissolved in cold water, milk, wine, beer, vinegar and the like can also be concentrated in accordance with the present invention. It is well known to those skilled in the art that the separation of liquids covered on ice surface is a critical step for all freeze concentration systems. The systems and processes of the present invention, whether implemented in a single stage or a two stage system, provide substantially effective and efficient separation of the covered liquid while promoting significant ice crystal growth rates.

It will be appreciated that changes and modifications can be made in the above embodiments without departing from the scope of the invention. For example, separation means other than a tandem filter, such as a centrifuge, can be used to separate the concentrate from the system. Likewise, other crystallites and / or multiple paralleled crystallites may be used instead of scraping heat exchangers. Therefore, it is intended that the scope of the invention only be limited by the appended claims.

Claims (38)

A device for lowering the peripheral viscosity of ice crystals in an aqueous solution formed in a freeze-concentrating system, comprising: a slurry inlet for introducing ice slurry in an aqueous solution to a column at one end of the column, a liquid discharge device and a freezing point for discharging liquid from the column Filter device in the middle of the slurry inlet and the liquid discharge device in the column to separate the liquid from the liquid portion of the slurry, and the ice crystals coming up from the opposite end of the column into a permeable ice crystal mass layer to control the degree of extrusion of the ice layer. Apparatus comprising a device rotatable and perforated adjacent to the opposite end of the column, the device for inhibiting and controlling the upward movement of the ice bed and discharging the ice from the ice bed, and the dilute liquid in the column for the rotatable and perforated device Liquid inflow in opposite end to feed up To reduce the viscosity around the freezing point in the aqueous slurry formed in the freeze-concentration system, characterized in that consisting of a gradient column having a slurry discharge device at the opposite end to discharge the ice slurry separated in the ice layer in the dilute liquid from the column Device for. An apparatus according to claim 1, wherein said filter device is comprised of a screen member mounted between a slurry inlet device and a liquid discharge device in a column. 2. A blade according to claim 1, having a blade rotatably mounted adjacent said slurry inlet device, and a scraper on one surface applied to remove ice from said ice layer and ice separated from said ice layer as a disc. And said rotatable disc having an opening extending therethrough. 4. The apparatus of claim 3 including a device for varying the rotational speed of the disc to control the degree of compression of the permeable ice layer. A method for lowering the peripheral viscosity of ice crystals in an aqueous slurry formed in a freeze-concentrating process, comprising: forming an ice crystal slurry covered with the first liquid in a first aqueous solution into a permeable rising ice crystal mass layer, and forming a permeable ice crystal mass layer Contacting the countercurrent of the second aqueous solution, which is thinner and less viscous than one liquid, and controls the penetration of the ice crystal so that the second liquid passes through the entire ice crystal layer and replaces the first liquid covered by the ice crystal under the ice crystal layer. And the ice covered with the second liquid is separated from the permeable ice crystal layer, and the ice separated from the ice crystal layer is formed into a slurry and transferred to the second liquid to be transported in the ice crystal layer. To lower the ambient viscosity of the ice crystal in the aqueous solution slurry formed in the invention. The method according to claim 5, wherein the ice crystal slurry in the first aqueous solution is subjected to pressure to be continuously introduced to one end of the defined region, and the ice crystal portion in the slurry is separated from the liquid portion and the liquid portion is discharged from the defined region. Move the ice crystal portion from the one end of the defined region, inhibit the movement of the ice crystal portion to form the permeable ice crystal mass, and introduce the second aqueous solution onto the ice crystal layer at the opposite end of the defined region, the second A method for lowering the peripheral viscosity of ice crystals in an aqueous slurry formed in a freeze-concentration process, characterized in that it flows through a small portion of the liquid and flows through the ice crystal layer and the majority of the two liquids are configured to convey ice discharged out of a defined area from the ice crystal layer. 7. The method of claim 6 wherein the degree of penetration of the ice crystal bed is controlled by controlling the amount of ice exiting the ice crystal bed. 8. The first aqueous solution of claim 7, wherein the degree of penetration of the ice crystal layer has sufficient permeability to allow the second aqueous solution to flow evenly through the ice crystal layer, while the first aqueous solution is discharged from the region where the amount of the second aqueous solution passing through the ice crystal layer is limited. The method of lowering the peripheral viscosity of the ice crystal in the aqueous slurry formed in the freeze-concentration process, characterized in that it is sufficiently compressed so as not to dilute too much. 7. The method of lowering the peripheral viscosity of an ice crystal in an aqueous slurry formed in a freeze-concentration process according to claim 6, wherein the replacement of the first liquid covered by the ice crystal by the second liquid occurs in a portion of the ice layer adjacent to one end of the defined region. . The method according to claim 6, wherein the first aqueous solution is a concentrate having a solids content of 36% to 50% or an intermediate concentrate having a solids content of 10% to 30%, and the second aqueous solution has a lower solids content than the first liquid. A method for lowering the ambient viscosity of the freezing point in the aqueous slurry formed in the freeze-concentration process, characterized in that the. A continuous freeze concentration system for concentrating an aqueous feed solution, comprising: a crystallizer device for crystallizing ice from the liquid and processing a flow containing a first aqueous solution to form an ice slurry in the liquid; In order to lower the peripheral viscosity of the ice crystals introduced into the slurry, it is effectively combined with the crystallizer device, and the device separates the ice crystals from the first aqueous solution in the slurry, and the ice crystals are formed into a rising permeable ice crystal layer having a controlled permeability. A device, an apparatus for introducing a thinner aqueous solution into a gradient column to countercurrent to an ascending permeable ice layer to replace the ice-covered first liquid with said thinner aqueous solution, and said thinner aqueous solution from the ice layer to form ice into a slurry An inclined column having a device for moving to A recirculation device that is effectively coupled with the gradient column and the crystallizer device for supplying liquid separated from the negative to the crystallizer device, and capable of working with the gradient column to receive ice slurry in the thinner aqueous solution from the gradient column. Water condensate, comprising at least one concentration step having a device for introducing wash water therein and having a washing column device adapted for washing and separating ice from said thinner water. Continuous freeze concentration system for the dragon. 12. The freeze-concentration system of claim 11, wherein a filter device is provided between the crystallizer device and the gradient column for discharging the first aqueous solution portion from the slurry. The slanting column device according to claim 11, wherein the slanting column device comprises: a slurry inlet device for introducing the ice slurry in the liquid into the slanting column device; a liquid ejecting device for ejecting liquid from the slanting column device; A filter device between the slurry inlet and the liquid discharge device for separation, a scraper device rotatably mounted adjacent to the slurry input device, and an opposite end of the column to inhibit the upward movement of the ice bed and to separate the ice crystals from the ice bed. A rotatable disc adjacently mounted across the warp column device and having an opening therethrough for passing ice crystals separated from the ice, and a liquid at the opposite end of the warp column device to introduce a thinner aqueous solution into the warp column Inlet device and ice slurry in thinner aqueous solution Freeze concentration system comprising a slurry discharging device in the opposite end of the gradient column, in order to. The freeze concentration system according to claim 13, further comprising a device for rotating the scraper device and the disc device in opposite directions. The freeze-concentration system of claim 13, wherein the ice slurry in the first aqueous solution is introduced into the warp column at a point between the filter device and the rotatable disc device. 12. The process of claim 11 having a two stage concentration system configured in combination with the first stage for concentrating the dilute aqueous solution stream, the first stage treating the stream containing the intermediate concentrate to crystallize and mediate the ice in the liquid. A first crystallizer device for providing an ice slurry of a concentrate and a device for introducing a stream containing an intermediate concentrate into said first crystallizer, and said slurry being introduced to lower the peripheral viscosity of the ice crystal portion of said slurry, A filter device for separating the ice crystals from the intermediate concentrate, an apparatus for shaping the ice crystals into a rising permeable ice crystal mass layer having a controlled permeability, and introducing a thin liquid into the gradient column to countercurrent to the rising ice layer to cover the ice crystals. A first inclined column apparatus having a device for replacing the concentrate with a dilute liquid, and an ice crystal sludge in the intermediate concentrate Is introduced into the first inclined column apparatus from the first crystallizer apparatus, the apparatus for discharging the ice crystal covered with the dilute liquid from the permeable ice layer in the first inclined column and forming the ice crystal slurry in the dilute feed liquid, and the first inclined column A washing column device having a device for discharging the intermediate concentrate from the device, a device for washing the ice discharged from the ice layer in the first slope column device, separating the diluted thin feed solution, and introducing the washing water into the inside; and A device for introducing an ice slurry from the first gradient column apparatus, a device for discharging the ice slurry from the washing column, the second step includes a second crystallizer apparatus for treating the concentrate to form an ice slurry of the concentrate; The filter device for discharging the concentrate portion from the slurry made in the second crystallizer device, and the ice crystal made in the second crystallizer device are concentrated. A filter device that separates the concentrate from the liquid and replaces the concentrate covered with the ice crystal with an intermediate concentrate, and separates the ice crystal in the slurry from the concentrate, forming the ice crystal into an ascending permeable ice crystal layer with controlled permeability, and a first A second inclined column apparatus having a device for introducing an intermediate concentrate discharged from an inclined column apparatus into a second inclined column apparatus and flowing back to the permeable ice layer to replace the concentrated solution covered with ice crystals with an intermediate concentrate; and the ice crystal slurry in the concentrate. A device for introducing the decanter from the determinant device to the second gradient column device, an ice crystal covered with the intermediate concentrate in the permeable ice layer in the second gradient column to form the ice crystal slurry in the intermediate concentrate, and an ice crystal slurry in the intermediate concentrate. A device for moving to said first crystallizer device, and a concentrate to said second crystallizer device A freeze concentration system having a device for discharging from said second slope column device for introduction. 17. The filter device of claim 16, wherein both of the first and second sloped column devices are secured transversely to the sloped column adjacent to one end of the sloped column and separate the ice from the liquid portion of the slurry, and the opposite end of the sloped column. Adjacently mounted to the column transversely and having a scraper device for separating ice from the permeable ice layer and a rotatable disc having a through opening for passing ice crystals separated from the ice layer, and rotatably mounted adjacent said one end of the column And a device for introducing the ice crystal slurry in the liquid into a gradient column at a point between the blade and the disc and the motor device for rotating the blade, and the filter device and the rotatable disc. 18. The rotating device according to claim 17, wherein the filter device is composed of a screen member adjacent to the bottom of the inclined column and fixed horizontally to the inclined column, wherein ice slurry in the liquid is introduced onto the top surface of the screen member in the inclined column, A freeze concentration system mounted transversely to the column adjacent the top of the column. 18. The freeze-concentrating according to claim 17, wherein the rotatable disc has a penetrating opening of a size and quantity sufficient to cause the ice crystal separated in the ice layer to pass upwards through the disc and for the countercurrent flow of liquid to flow through the disc into the ice layer. system. A continuous countercurrent freeze-concentration method for concentrating an aqueous solution, wherein a stream of aqueous feed is introduced into the permeable ice crystal mass layer covered with the concentrate in a countercurrent flow so that the concentrate covered by the ice crystal is replaced by the feed liquid and the size of the ice crystal grows. Cooling the liquid replaced from the ice crystal to crystallize the ice and form a viscous ice crystal slurry in the concentrate, circulating the viscous ice crystal slurry in the concentrate into the permeable ice layer, separating the concentrate portion of the viscous slurry from the ice portion, and The ice portion of the viscous slurry is formed into a layer of permeable ice crystals covered with a concentrate to contact the feed liquid, the penetration of the ice crystal layer is controlled, and the ice crystals covered with the expanded feed liquid are separated from the ice layer to form the ice crystal as a slurry. Transferred to a feed concentrate to form, and Continuous reflux for aqueous solution concentration comprising introducing an enlarged ice crystal slurry in the feed liquid into the washing column to separate the ice portion of the slurry from the feeding liquid in the washing column and replacing the feed liquid covered by the ice crystal with the washing water. Freeze Concentration Method. 21. The method of claim 20, wherein the concentrated portion of the viscous slurry is withdrawn and recovered as a product while simultaneously circulating the viscous slurry into an ice crystal bed. 21. The method of claim 20, wherein a majority of the water soluble feed stream introduced into the ice crystal bed combines with the enlarged ice crystal separated from the ice crystal bed to form a slurry and is introduced into a wash column, with the remainder of the water soluble feed stream flowing into the ice crystal bed. A continuous countercurrent freeze concentration method that passes through and replaces the concentrate covered therein. 22. The method of claim 21 wherein the aqueous feed liquid has a solids content of about 2% to 20% and the concentrate has a solids content of at least about 36%. 21. The method of claim 20, wherein the feed liquid separated in the wash column is recycled for introduction into the ice crystal bed. 21. The method of claim 20, wherein the flow of the aqueous feed liquid flows back down to the rising permeable ice crystal bed and down. The viscous ice crystal slurry in the concentrate according to claim 20, wherein the viscous ice crystal slurry in the concentrate liquid pumps the slurry to one end of the defined region, separates the ice crystal from the concentrate portion of the slurry, and discharges the concentrate portion in the defined region, and the ice crystal. Is formed into a permeable ice crystal mass layer in the inclined region by moving upwards within the confined region and at the same time suppressing and controlling the upward flow of the ice crystal, and forming a permeable ice layer by separating the ice crystal at the top of the ice crystal layer. Reflux freeze concentration method. 27. The method of claim 26, wherein the degree of compaction of the ice crystal bed is adjusted by adjusting the rate of ice crystal discharge from the bed. 28. The method of claim 27, wherein the degree of penetration of the ice crystal bed is sufficient for the aqueous feed solution to flow back and forth across the ice crystal bed, while the amount of feed liquid passing through the ice crystal bed is sufficient to not dilute the concentrated liquid discharged in the confined space. Continuous countercurrent freeze concentration method that is compressed. 27. The method of claim 26, wherein the concentrate stripped from the ice crystals is combined with the middle concentrate portion of the viscous slurry to form a combined concentrate stream, from which it is cooled to crystallize ice to form a viscous slurry. A continuous multi-stage freeze-concentration method for concentrating a water-soluble liquid, in which a stream of water-soluble feed solution is covered with an intermediate concentrate in a first concentration step in order to replace the ice-cold intermediate concentrate with a rapid concentrate and grow the size of the ice crystal. It is introduced countercurrently, the intermediate concentrate is discharged in the first concentrate stage, the ice crystals covered with the expanded rapid concentrate are separated from the ice layer in the first concentrate stage, and the ice crystals are transferred to the feed concentration solution to form the slurry. In order to separate the feed concentrate from the enlarged ice crystal, the ice crystal slurry of the feed concentrate is passed through the washing column, and the permeated ice crystal mass covered with the intermediate concentrate discharged from the first concentration step to replace the concentrate covered with the ice crystal with the intermediate concentrate. The bed was introduced into the second concentration stage under reflux, and the ice crystals covered with the intermediate concentrate were The ice crystal slurry in the intermediate concentrate, which is separated in the ice layer of the axial stage, is transferred to the intermediate concentrate to form the ice crystal as its slurry, and the ice crystallizes from the liquid and forms the concentrated ice crystal slurry in the intermediate concentrate. Cooling the concentrated slurry from the intermediate concentrate portion having an intermediate concentrate portion of the separated concentrated slurry combined with the intermediate concentrate replaced in the ice crystal bed in the first concentration stage, and circulating the concentrated slurry to the permeable ice layer in the first concentration stage. Forming a combined flow of the intermediate concentrate discharged from the first concentration step, forming an ice crystal part of the thick slurry in the permeable ice crystal mass layer covered with the intermediate concentrate in the first concentration step, and Adjusts the permeability of the ice crystal bed, discharged from the second concentration step The liquid is cooled to crystallize liquid loaf ice, to form viscous ice crystal slurries in the concentrate, to circulate the viscous slurry of the permeable ice layer in the second concentration step, and to introduce the viscous slurry into the second concentration step before the viscous slurry is introduced. Separating the concentrate portion from the concentrate portion of the viscous slurry, the concentrate portion of the separated viscous slurry with its concentrate portion having a separate concentrate portion of the viscous slurry combined with the concentrate replaced in the ice crystal bed of the second concentration step. Separating to form a flow of combined concentrate exiting the second concentration step, forming an ice crystal portion of the viscous slurry into a permeable ice crystal layer covered with the concentrate liquid in the second concentration step, and an ice crystal layer in the second concentration step. Continuous multistage for concentration of water-soluble liquids, characterized by controlling the penetration of How to freeze enrichment. 31. The solids content of claim 30, wherein the solids content of the feed liquid is from about 2% to 20%, the solids content of the liquid portion of the thickened slurry is from about 10% to 30%, and the solids content of the liquid portion of the viscous slurry is at least about 36. Continuous multistage freeze concentration method in%. 32. The liquid permeable ice crystal according to claim 30, wherein the permeable ice crystal layers in the first and second concentration stages pump to one end of the enclosed region of the ice crystal slurry in the liquid, separating the ice crystal from the liquid portion of the slurry, and the liquid portion enclosed region. Discharges the ice crystals from the opposite end of the slurry introduced end, while inhibiting and controlling the flow of the ice crystals to form a layer of ice crystals within the sealed area, and A continuous multistage freeze concentration method formed by discharging an ice crystal at the opposite end of the ice crystal. 33. The method of claim 32, wherein the slurry is introduced under pressure at the bottom end of the enclosed region, the ice crystal mass is moved upwards in the region, and the ice crystal is discharged at the top of the ice crystal bed. 33. The method of claim 32, wherein the degree of compaction of the ice crystal bed is adjusted by adjusting the rate of ice crystal discharge from the bed. 35. The method of claim 34, wherein the degree of penetration of the ice crystal bed is sufficient to allow the aqueous feed solution to flow back and forth across the ice crystal bed, while the amount of feed liquid passing through the ice crystal bed is sufficient to not dilute the concentrated liquid discharged from the confined space. A continuous multistage freeze concentration method that is compressed. 31. The method of claim 30, wherein the majority of the water soluble feed liquid introduced into the first concentration stage is combined with an enlarged ice crystal separated from the ice layer of the first concentration stage for introduction into the wash column, wherein the remainder of the water soluble feed liquid is the ice crystal layer. A continuous multistage freeze-concentration method that passes through and replaces the intermediate concentrate covered therein. 31. The method of claim 30, wherein the majority of the intermediate concentrate introduced into the second concentration stage combines with ice crystals separated in the ice layer of the second concentration stage to form a slurry and moves to the first crystallizer region to form a thick slurry. And wherein the remainder of the intermediate concentrate passes through the ice crystal bed in the second concentrated zone and replaces the concentrate covered therein. 31. The method of claim 30, wherein the feed liquid separated from the ice crystals in the wash column is recycled for introduction into the first concentration step.

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