UA53239C2 - Method for desalination and concentration of aqueous solutions by multi-stage freezing-out and multi-stage desalter- concentrator for realizing the same - Google Patents

Abstract

The invention relates to freezing-out method for desalination of salt waters and purification of anypolluted aqueous solutions for obtaining melt potable water, and also for concentration of aqueous solutions, e.g. edible liquids-frit juices, process solutions of chemical, food, pharmaceutical industries for the purpose of obtaining concentrates of any degree of concentration. A method for desalination and concentration of aqueous solutions by multi-stage freezing-out comprises multi-stage freezing out ice from aqueous desalinated solution by means of boiling refrigerating fluid. The method comprises also separated recirculation processes forgeneration of ice and growth of ice crystals in any degree in successive dehydration of solution with increasing concentration thereof, separation andwashing ice from concentrated brine and melting ice. Multi-stage freezing-out desalter-concentrator contains stages, every of which consists of evaporator-ice generator and separate capacities-crystallizers under it, screw disposed between evaporators-ice generators and capacities-crystallizers, recirculation pumps, separation washing out, right angle in the plan column and refrigeration unit consisting of compressor, condenser, additional condenser, evaporators disposed in inter-tube spaces of ice generators, receivers and throttle valves. The invention provides a versatility of work with any initial aqueous raw material, any degree of dehydration, with obtaining any concentrates, which substantially extends the field of use.

Description

The invention relates to a freezing method of desalination of salt water and purification of any contaminated aqueous solutions - for obtaining purified melt lightened drinking water, as well as concentrating aqueous solutions, for example food liquids - fruit juices, sugar solutions, brines, technological solutions of chemical, food, pharmaceutical industry in order to obtain concentrates of any degree of concentration up to eutectic, at which crystals of the second solid phase - salts, sugar, etc. can be obtained. The freezing method of desalination and concentration of aqueous solutions consists of 3 fundamentally necessary operations: 1. freezing of ice from salty, food or any other aqueous solution; 2. separation of ice crystals from the concentrate and washing of this ice from the ice crystals covering the concentrate film; 3. ice melting.

As a result of the specified processes, 2 products are obtained - pure melt water of drinking standard and concentrate, the concentration of which depends on the degree of dehydration of the original aqueous solution. Depending on the type of final product, the same installation is called a desalination plant or a concentrator.

Many methods, schemes and designs of freezing desalination concentrators (VOK) have been proposed.

Freezing of ice from an aqueous solution (melting of ice) is carried out: 1. non-contact, that is, the heat of ice formation (melting) is removed (fed) through a heat-transfer surface; 2. contact, i.e. liquid refrigerant (refrigerant vapor) boils (condenses) in the antifreeze solution (on ice).

Separation and washing of ice from the concentrate is carried out in hydrocyclones, centrifuges, separation and washing columns.

The most complete level of the technique of concentrating food liquids (fruit juices) is described in the book - L. Pap.

Concentration by freezing, Moscow, Light and Food Industry Publishing House, 1982. Pages 50-52 of this book describe a multi-step method used in Germany for various food liquids. A suspension of ice crystals and concentrate in each of the 3 stages is formed in 2 melts. The nuclei of ice crystals are formed in the previous crystallizer, which is cooled to a temperature of minus 10"C, and is equipped with a scraper knife. Then this suspension is fed into the second crystallizer, which is cooled to a temperature of ---50"C, where large ice crystals are formed. A continuous centrifuge is used to separate the suspension and wash the ice. Inert gas is used to prevent juice oxidation.

After the second crystallizer, the suspension is separated in a centrifuge. The separated concentrate is fed to the second stage (its equipment is similar to the equipment of the 1st stage and the processes are similar, withdrawal - the concentration of the concentrate increases), and then to the same third stage, after which the concentrate is removed as a product.

The ice after all 3 stages is mixed and melted in the melter.

The disadvantages of this method and scheme are as follows; 1. Low temperatures of ice formation lead to increased electricity consumption; 2. The need to have an unreliable mechanism for scraping ice in crystallizers;

C. Separation and washing of ice from the concentrate is carried out in each stage, which leads to under-washing of ice in stages 2-0 and especially 3 due to high concentrations of the original concentrate before the washing operation and excessive loss of dry substances.

A known multi-stage freezing method for concentrating aqueous solutions and an installation for its implementation | see OSH.5. Raiepi Me4666484, Mau 19,1987, Miyiziade iyeege sopsepigayipod rgosez apa arragaishv). In this method - a prototype, the initial aqueous solution is frozen in 3 stages, in which the processes of ice generation (in shell-and-tube vertical evaporators - I-LH ice generators) and ice crystal growth (in Kr crystallizing tanks) are carried out. Refrigerant boils in the intertube space of the second I-LH2 and the third I-LHz, removing the heat of ice formation, and in the tubes, with the help of recirculation pumps, an aqueous solution circulates, in which ice nuclei are generated, which then, falling into the second crystallizer

Kr" and the third Krz, grow to the size of 100-200 tKt. Between the second I-LH" and Krg and the third I-LHz and Krz there is an auger, the bottom of the body of which is perforated with holes. The ice-brine suspension from the first cuttings I-LH" and I-LHz flows on the branches of the auger and then through its bottom perforation enters the Kr and Krz, while the large ice crystals do not pass through the perforation of the auger and move into the first crystallizer (this Kr does not have an accompanying I-LHz), from where, after crystallization and selection of new ice crystals, they are removed from the installation by the second auger. The initial aqueous solution (for example, fruit juice) is introduced into the first Kree crystallizer, mixing with ice from the third I-LHz and the second I-LH." The final concentrate as a product is selected from the third Krz. From the first Kry in the direction to the second I-LGho-Kr" and the third of the I-LHz-Krz tandems, the concentration of the concentrated solution and proportionally its viscosity increase.

The disadvantages of this method and device are as follows: 1. It is impossible to obtain lightened water (that is, water with a reduced content of heavy water DgO), which has a proven beneficial effect on living biological objects (and on humans). 2. Removal of ice from the first Kree crystallizer using an auger is difficult, since the ice is in the aqueous phase environment and the effects of its floating and sliding in the liquid prevent (experimentally established!) its movement. Turbulization of Kree with stirrers does not eliminate this difficulty because in . ice mass during its accumulation and during the operation of agitators, channels are formed, which are filled with solution, in which the blades of the agitators rotate, and "standing" ice forms around them. 3. Mixing the original solution with ice in the first stage of crystallization after the second and third stages of freezing does not allow to fully use the potential of this reception (to reduce the viscosity of the brine of the surface film covering the ice crystals and facilitate their subsequent washing from this brine). It is preferable to use this reception not during the first ice formation, as in the prototype, but already after its implementation. This drawback, which is not obvious at first glance, is very significant in view of the effect of recirculation in the 1st stage, as the following example shows. Let the original orange juice have a concentration

(expressed indirectly as given in the description of the prototype through the units of viscosity Vhih and in the first approximation directly proportional to iy) bo-120od. (its output is So-2bgallons/min - we will indicate, to facilitate the examination, the values of the units of measurement are the same as those given in the prototype patent /see the table in columns 5 and 6/). After the 1st stage, the concentration of concentrated juice will be 51-180d. and the cost of its recirculation in the 1st stage is equal to С1-74 gal/min, after the 2nd stage it is 52-С0од, after the 3rd stage - 53-450од. The displacement of the original juice with the recirculate of the 1st stage gives the concentration of the mixture

Mixture-(05oa1 51) (Sbo-C1)-(26 12-74 18)/(26-4-74)-16 ,440 units.

Ice crystals at the exit from Krz will be contaminated with a film from this concentrate. When the original juice is fed to the displacement with ice, previously already drained on the auger from the concentrate, then its surface film will have a concentration equal to almost 5o-12od. Such ice is easier to wash off from a concentrated film.

In addition, in the prototype, a small amount of the original solution is mixed with a large amount of recirculation concentrate, which has a reduced temperature, which practically does not increase the temperature of the original ice, which in turn increases the viscosity of the concentrate film. Refusal to accept the prototype, as it is done in our proposal and in this equalization point, is favorable for better washing of ice from the concentrate and reduction of losses of dry substances with ice. 4. In the course of its movement through the degrees of freezing, the concentration increases in the concentrated solution, that is, the equilibrium temperature of freezing decreases. The boiling of the refrigerant in the stages of the evaporator-ice generators in the prototype is supported by a refrigerating machine at a constant temperature, which to ensure heat transfer must be below the lowest freezing temperature, that is, the same as in I-LHz. This leads to a large temperature difference between the freezing temperatures of the solution and the boiling temperature of the refrigerant in the first 2 stages of concentration, which leads to irreversible losses of work, and, most importantly, to the formation of conditions for freezing of ice from the circulating solution on the inner surface of the evaporator tubes. We note that the condition for the tubes not to be blocked by ice consists not only in ensuring high speed circulation of the solution in the tubes, not only in the hydrophobicity of the inner surface of the tubes, not only in a small amount of ice in the flow (up to 5-7905), but also in a small temperature difference when removing the heat of ice formation, which, according to experimental data, does not exceed 3.5"С. In the prototype, this condition is not met. And in order to come close to fulfilling this condition in the prototype, a second refrigerator must be installed. 5. In the prototype, the concentration of fruit juices and sugar solution to concentrations of the order 6095 and temperatures down to minus 21 "C, at which the thick syrup has a high viscosity (more than 800-1073 Pa"s) and a low rate of crystal growth, and moreover, the eutectic concentration (64.995 for sugars) is not reached, at which, together with ice also crystallizes the second solid phase - crystals of salts, sugars, etc., and these two solid phases, which are in equilibrium with their saturated solution, must be separated and pour at a technically acceptable speed. A number of devices are known for the separation and washing of ice crystals from brine (concentrate) - centrifuges, squeeze screws, hydrocyclones, drainage and extrusion washing columns.

The most efficient and industrial distribution is the displacement separation and washing column

SPK, which works with back pressure (note: the principle of action and hydromechanics of this SPK are described in the handbook "Different areas of cold application", Moscow, Agropromizdat, 1985, chapter 9 "Opresnenie solenoy vodyi", see p. 247-248).

SPK can be circular or rectangular in plan. In the middle part of the column, on its side surface, there is a filter mesh through which roseol is filtered, and the ice does not pass through this mesh during its upward movement. The ice-brine suspension is supplied by the pump to the lower part of the column, the roseol is removed through the filter mesh, and the ice, having formed into a porous piston, moves upward by the "pumping" force, being washed from the surface brine film covering the ice crystals by the countercurrent downward movement of washing water. In the upper part of the column, the washed ice is broken by a rotating knife - a scraper or a conveyor belt and is dumped into a pocket adjacent to the column, from where it is sent by hydraulic transport to the ice melter-condenser of the refrigerant.

The disadvantages of this SPK are the presence of a mechanical device in the upper part of the column, which directs the ice mass into the ice melter-condenser of the refrigerant, and difficulties in organizing an effective process of transportation and melting of ice - condensation of the agent in the apparatus.

The task of the invention is to create a method of desalination and concentration of aqueous solutions by multi-stage freezing and a multi-stage freezing desalinator-concentrator, which would allow desalination with obtaining light water and with deeper extraction of desalinated water from the original saline solution before its separation to the dry residue (note: the technology of sea desalination of water and simultaneously concentrating it to 17-20965 - and to dry matter - is currently developed by the author to extract methane from the sea's huge deposits of methane gas hydrates /100 trillion m3/, buried at the bottom of the Black Sea shelf; this seawater concentrate will melt methane from gas hydrates, and travel pure thawed desalinated water is used as high-quality drinking water for arid Crimea); concentration of food liquids to higher concentrations - around 6095, overcomes the veil of high viscosity of highly concentrated, for example, juices at low temperatures to eutectic concentrations; reduction of capital costs for the refrigerating machine and simplification of its operation.

The problem is solved by the fact that when working in the desalination mode in the first stage, no more than 3-595 of the initial solution is first transferred to ice and this ice is dumped as enriched with heavy water, and the remaining initial solution is mixed just like the initial solution in the case of operation in the concentration mode with ice after it leaves the first stage of ice generation and before it is submitted for separation and washing.

At the same time, a non-azeotropic mixture of refrigerants, for example Ф22-Ф142в, is used as a refrigerant that removes the heat of ice generation during its boiling, which is introduced countercurrently with the flow of the desalinated solution into the last stage of ice generation along the course of the desalinated or concentrated solution and is withdrawn from the first stage of the desalinated or concentrated solution ice generation; at the same time, the concentration of a non-azeotropic mixture of refrigerants is determined by calculating - the product of the mass fraction of a low-boiling component (for example, F22) and the heat of its vaporization is equal to the heat of the ice melting process.

In the case of the formation in the last stage of ice generation and the growth of ice crystals of highly viscous concentrates, and equally and simultaneously with the ice and the generation and growth of the second solid phase - for example, crystals of salts, sugar, etc., which crystallize at the eutectic point, in the last blunted concentrate the desalinated (concentrated) solution is frozen in a mixture with an intermediate low-viscosity transport medium at temperatures from -102С to -302С (viscosity no more than 1 103 Pa s) to reduce its viscosity.

Liquids immiscible with water are used as a transport medium - for example, organosilicon liquid (silicone), unheated or boiling refrigerants, for example, Freon 11, carbon dioxide, etc. or gases, such as nitrogen, carbon dioxide vapors, sulfur dioxide, etc., with which the frozen concentrate is turbulently recirculated in the process of generating ice crystals (and crystals of the second solid phase) and in the growth process of these aforementioned crystals.

The proposed method is carried out in the device of a multi-stage freezing desalination concentrator, in which the evaporator - ice generators are inclined to the crystallisers at an angle of 115-302; the auger on the side that delivers ice to the separation and washing column is connected to the inlet of the mixing tank and raised; the auger(s) is inclined at an angle of 10-20" to the horizontal; the separation and washing column has a bent visor in its upper part on one side, which forms a passage with the upper edge of the column on the opposite side parallel to the cross-section of the column for passing ice and its changes in the direction of movement to 1802 in the adjacent chamber, in which the irrigation condenser of the refrigerant-ice melter is built in; the liquid refrigerant inputs to the evaporators-ice generators and the refrigerant outputs from them pass sequentially through the degrees of desalination and concentration of the solutions countercurrently with the flow of the dehydrated solution.

At the same time, the first flow of the initial solution in the desalination mode, the capacity-crystallizer has a removable window in the back section of the auger body for pouring out and dumping heavy water ice; in addition, this capacity-crystallizer when working in the concentration mode has a liquid phase level regulator, which maintains the suspension level above the level of the lower screw hole by 1/4 of its diameter; at the same time, a recirculation pulsation compressor is installed between the exit of the suspension from the capacity of the crystallizer of this stage and the entrance to the pipe space of the evaporator-ice generator of the same stage.

The essence of the invention is shown in Fig. 1 and 2.

Fig. 1 - scheme and design solution of a multi-stage freezing desalination concentrator VOK.

Fig. 2 is a constructive solution of the first for the desalination mode and the third for the concentration mode of food liquids - along the course of the processed solution - the degree of desalination - concentration.

Fig. 1 shows the scheme of the VOK, which consists of: - the system of inputting the initial solution - the output of desalination-concentration products; - degrees of ice generation and growth of ice crystals; - separation - washing column; - Refrigerator.

According to Fig. 1, the system of input of the initial solution - output of desalination-concentration products consists of a pump for supplying the initial solution 4, filters for coarse cleaning of the initial solution 5 and fine cleaning of desalinated water 6, a preliminary heat exchanger 7, a source of ultraviolet radiation 8 (bactericidal lamp for disinfecting desalinated water) . There are three stages of ice generation and growth of ice crystals (from right to left in the figure, they are defined as 1, 2, 3). Each stage includes a shell-and-tube evaporator of the refrigerant - the I-LH ice generator and below it a capacity-crystallizer Kr. Between I-LH and Kr there is an auger that moves ice from all three stages. The 1st and 2nd stages are structurally the same. The 3rd degree has cancellations. In the desalination mode, the initial saline solution "goes through" stages in the following sequence: 3, then 1, then 2.

In the concentration mode, the original food solution (for example, grape juice) "goes through" stages in the following sequence: 1,2,3.

In stage 1, the I-Lhi evaporator-ice generator consists of a body 9, 2 tube grates 10 and tubes 11.

The Kree crystallizer capacity of this stage includes a capacity 12, a stirrer 13, turbulating partitions 14 and a recirculation pump 15. The Kree can have adjacent walls with other similar devices, or it can have a separate body.

The auger 27 consists of a body 28, the lower part of which is perforated with holes with a diameter of 0.2 mm, and actually the turns of the auger 29. The left part of the turns of the auger 29 is removable (it is actually the second auger 29a, the right end of which is raised to an angle of 10-20") , has a joint assembly 30 (slot connection), allowing to change the joints of the screws to the opposite with the right unchanged part of it. In the desalination mode, the left part of the screw 29a has a left winding of turns, which moves the ice to the left; in the concentration mode, the left part of the screw 29a (inverted on 1807) has a right winding of turns, which moves the ice to the right. The left end of the auger 29a has a window 31, which is open in the desalination mode for pouring out heavy water ice, and is closed by a hermetic cover 32 in the mode of concentration of food liquids. The augers also have a reducer 33, which ensures their rotation with a speed of 10-20 rpm, and an electric motor 34. The right open end of the auger 27 - from the side that delivers ice to the separation and washing column - is connected to the inlet of the mixing tank 35 and raised by d at an angle of 10-20" to the horizontal.

The tank 35 has a stirrer 36, turbulating partitions 37 and a pump 38.

The separation and washing column of the SPK consists of a rectangular in plan (i.e., when viewed from above) body 39 and filter grates 40 located on the side surface of the SPK, having the size of holes "in the world" of 100-200 μm (through these holes roseol /concentrate/ flows, but is retained ice crystals - even in the case when the crystals have smaller sizes - the well-known "crowd effect" works). In its upper part, the SPK has a bent visor 41 on one side, forming from the upper edge of the column on its opposite side 42 a passage 43 parallel to the cross-section of the column for rolling ice and changing its direction of movement to 1802 in the adjacent chamber 44, in which the refrigerant irrigation condenser is built - ice melter 45.

The refrigerating machine (HM) consists of a single-stage compressor 46, a refrigerant condenser - an ice melter 45, an additional air condenser 47, a heat exchanger 48, liquid refrigerant receivers 49 and 50 and throttling valves 51 and 52. The HM is switched so that when all the valves defined with the letter O, the installation works in the desalination mode, and when all the valves identified by the letter K are open, it works in the concentration mode. Solenoid valves O and K are all switched simultaneously ("all at once" command).

According to Fig. 2, stage C has an evaporator-ice generator I-LHz 3, a capacity-crystallizer Krz 54, pumps 20 and 21, a mixer 55, a liquid phase level regulator 57, a pulsation compressor 58. The evaporator-ice generator I-LHz is inclined to a capacity-crystallizer Krz at an angle of 15-30" (the same feature of the design is also in stages 1 and 2; this is provided so that in the event of a staff error - an increase in the temperature difference during heat transfer in I-LH by more than 3.5"C and possible with such errors in the deposition of ice on the inner surface of the evaporator tubes - it would be possible, by stopping the operation of the stage (for 3-5 minutes) and heating the intercoarse space with a hot refrigerant after pumping the compressor, to allow the tube ice to quickly (1-2 minutes) move onto the turns of the screw).

In the scheme of step C, there is also a separator of the transport medium 70 with the lines of return of the medium 71 and the output of the product concentrate 72. The design of the separator 70 and the principle of its action can be different and are not detailed in the diagram. It can be: - simply a settling tank - when the densities of the liquid carrier and the product concentrate differ by at least 10Okg/m2; - it can be in the form of an evaporator with a heat exchanger, when the carrier is a low-boiling liquid, for example F-11, СО» or 50»; - it can also be in the form of a degassing column, in which a membrane compressor selects a dissolved gas carrier from the concentrate; - in the event that in stage C the crystallization processes are carried out at the eutectic point, when heavier sugar crystals are formed together with ice crystals, then the separator 70 can be made in the form of a screw, which will squeeze these sugar crystals from the saturated solution, dry them to dryness and release in the form of a dry dissolved powder (the author has such a device ass. USSR Me1576125, patents of Ukraine

Me13808 and Me23240). Thermophysical properties of some desalination and concentrating solutions and transport media used in the present invention in degree C

Table - temperature, pressure, concentration, density, viscosity,

Z. Freon!i!i -:/// | 77770 | 25.73 | -::- | 1557. - 11111117 7111820 | 1527 | ..- | 1465 | 0345109 ( o5. Carbon dioxide CO» | -3 | 2421 | -(- | 998 | 050 --11111117111la3 | 71787 | // 77171 | 77777 ob. Sulfur dioxide HO | o | --"- | 1460 | case -k- 11111111 Y711»3 | 533 | 7777-7177 1487 | 045103

In the desalination mode, the VOK works as follows. The initial saline solution is fed by the pump 4 to the coarse filter 5, in which the solution is cleaned of coarse suspensions up to 5 μm in size. Then the solution is cooled in the previous heat exchanger 7 to 3-57C and sent through pipeline 69 to the capacity - crystallizer 54 (Krz). From Krz, the solution is selected by pump 21 and is fed through lines 22 and 25 into the pipe space of the evaporator-ice generator of stage C (I-LHz). During the movement down the tubes, the solution is cooled due to the cold (heat of vaporization) of the refrigerant boiling in the intertube space, partially freezes and, together with the ice crystals, flows from the lower part of the I-LHz to the turns of the screw 29a and then through its bottom perforation of the housing 28 in the Krz. The operation of the refrigerating machine (i.e., the amount of refrigerant supplied to the I-

LhGz) cold productivity of I-LHz is created in such a way that when working in the desalination mode in the first stage, no more than 3-595% of the initial solution freezes by mass.

This ice is enriched with heavy water DgO. Enrichment is based on the effect of the increased temperature of ice formation of heavy water (13.8"С) - a thermodynamic factor. This factor (necessary, but not sufficient) must be strengthened by a kinetic factor - mixing of the solution during its ice formation in order to interfere with the formation of D»2O ice decrease in the concentration of heavy water molecules at the surface of ice formation due to their reduced mobility (by 10 times) compared to light water molecules, i.e.

Ngo.

When the ice enters the auger cavity, it is retained by the perforation of the auger body and moves with its turns 29a to the left in the direction of the window 31 (the cover 32 is moved away from the window 31 in this mode), overflows through the window 31 into the funnel and together with the transport water (it overflows through the window 31 ) along line 23 is discharged into the sewer using pump 20. Discharge of the "first ice" (its formation in the volume of the flow and not being retained on the walls of the tubes depends very much on the intensity of the turbulence of the flow at the walls of the tubes 1-

LHz) provides relief of desalinated melt water (that is, a decrease in the content of deuterium in desalinated water by 10-2590 compared to the amount that is usually found in natural water, in which its content is 0.035-0.0495 mol).

The 3-595 range of discarded ice is justified as follows: when exceeding 595, the loss of work on freezing "non-product" increases too much; when decreasing below 395, it is difficult to regulate this small flow and, in addition, there is a possibility of not achieving the goal of this operation - the relief of the still unfrozen solution that remains.

The unfrozen source solution (in the form of recirculate after pump 21) is sent along line 26 to mixing tank 35, where it is mixed with ice moved to the right into this tank by screw 27 (more likely - by its turns 29). Turbulization in the tank 35 of the ice-brine suspension ensures its selection together with the ice by the pump 38 and its delivery along the line 74 to the lower part of the separation and washing column

SPK In this device, the suspension moves upwards. The roseol is filtered through the filter grates 40 and is returned to the top ice irrigation line 75 by the movable auger 27 to the right between stage 1 and the tank 35. This roseol, having a lower concentration compared to the brine film on the ice, prewashes this ice before it enters. into tank 35 and then flows down the slope to the left (a 10-20" slope is enough for the liquid to flow to the left, it is irrational to make a slope with an angle of more than 207 in view of the increase in the vertical dimensions of the 1st stage) down through the perforation of the bottom of the auger housing into the capacity-crystallizer 1- 8th degree of Cree.

The circulation of brine - tank 35, line 74, the lower part of the SPK, grid 40, line 75, the right part of the auger between I-LGi and tank 35 - preliminarily promotes the further effective operation of the SPK, namely: - increases the temperature of the ice, which prevents it from freezing at the bottom SPK; - reduces the concentration of the brine film covering the ice crystals; - reduces the viscosity of the brine, which improves the filtration of the brine at the bottom of the SPK - first through the mass of ice, and then through the cells of the filtration grates.

From the bottom of the Kri, the pump 15 selects roseol and directs most of it along the line 17 into the pipe space of the I-LGIi.

During the circulation of brine through the tubes, it is necessary to withstand the conditions of its non-freezing and clogging of the tubes with ice, which is ensured by the high flow rate and the small temperature difference between the freezing temperature of the solution at a given concentration and the boiling temperature of the refrigerant in the intertube space. Ice nuclei are generated in the I-LH tubes, their sizes are small (1-10μm) due to the high velocity of the flow (1m/s). Such microsizes of ice ensure their passage through the ice mass transported by the auger from left to right, as well as through the perforation of the bottom of the auger into the Krz crystallizer capacity. The volume of Kr is calculated for the time the brine stays in it for about 5 minutes, which ensures the growth of ice crystals when the suspension is turbulated with a stirrer 13 to the size of 150-250 μm. When brine is recirculated through the ring (pump 15, line 17, I-Lhi tubes, auger with ice), the ice mass in the cavity of the auger as a classifier passes small seed crystals and retains relatively large ice crystals, forming from them a snow mass subjected to transportation.

In I-LH: the concentration of brine by salts increases to the optimum; usually, at this level, about 8095 ice is frozen. The pump 15 directs a smaller part of the recirculated water through the pipe 18 to the 2nd stage of freezing - first to the surface of the ice, which is moved by the auger between I-LH" and I-LGi for the purpose of its partial washing, and then to Kr".

The processes in stage 2 are similar to the processes in stage 1 (at the same time, the pipe 21 is blocked by a shut-off valve - not shown). The concentration of the brine increases to the final one, at which it is removed from the Kro using the pump 19 through the pipeline 71 and through the heat exchanger 7.

After the ice is separated from the brine in the middle part of the SPK, the ice moves up, being washed from the surface brine film by the countercurrent lowering of the washing water from line 76, which penetrates the porous ice piston and then mixes with the filterable brine in the area of the filtration grate. In the upper part of the SPK, the ice mass washed from the brine with the help of the guide visor 41 turns its movement by 180" and descends into the adjacent chamber 44. The section 43, parallel to the section of the SPK, does not compress the snow mass and does not reduce its porosity and permeability, which does not impair washing process. In the adjacent chamber 44, the ice mass is liquefied by fresh water supplied through line 77 and is in contact with the surface of the built-in irrigation condenser of the ice-melting refrigerant 45. In this apparatus, the refrigerant condenses, melting the ice with the heat of its condensation. The melt water from the bottom of the chamber 44 is removed by pump 78, part of it (larger) is recirculated through line 77 again into chamber 44 - to increase the heat transfer coefficient from the ice-water suspension, part through line 76 enters the SPK as washing water, and the remaining part through line 80 through heat exchanger 7, a fine filter 6 and a disinfecting device 8 are discharged from the VOK as a product of pure, lightened, disinfected drinking water high quality

The refrigerator in desalination mode works as follows. Compressor 46 compresses a non-azeotropic mixture of refrigerants (recall: a mixture is called non-azeotropic when its equilibrium compositions of the liquid and gas phases differ; in the temperature-composition diagram at constant pressure, such a mixture is represented by a "fish", in which the upper curve, which shows the composition of the gas phase, does not intersects with the lower curve, which shows the composition of the liquid equilibrium phase; a characteristic feature of such a mixture is that it boils at constant pressures and condenses at variable temperatures (during boiling, the low-boiling (low-boiling) component first boils off at the lowest temperature, that is, the component /in our case - Ф22/, which has a lower saturation temperature at the same pressure as the second component, after which the second component begins to boil out - a hard-boiling /high-boiling one, in our case - Ф142в/, and the boiling point of such a mixture gradually rises; when condensing such a mixture, it initially condenses almost completely hard-boiling component, and the second component will condense at the same common pressure of the mixture, but with a decrease in temperature and under its partial pressure). After the compressor 46, the compressed mixture enters the additional condenser 47, in which the high-boiling component - F142v - is condensed due to heat exchange with air. The vapor-liquid mixture flows through the pipe 81, through the heat exchanger 48 and through the pipe 82 into the receiver 50, in which the liquid and gas phases are separated. The liquid phase - mainly the high-boiling component (Ф142в) - is throttled in the throttle valve 51 and flows to mix with the low-boiling component (Ф22). The gas phase from the receiver 50 - mainly the low-boiling component (F22) - flows through the line 83 into the irrigation condenser 45, built into the chamber 44 of the SPK. Here, the low-boiling component condenses during heat transfer with ice and already as a liquid flows into the receiver 49, from where it flows along line 89 and after throttling in the throttle valve 52 to mix with the high-boiling component (F142b). The mixture of refrigerants in the desalination mode passes through the evaporators-ice generators countercurrently to the desalinated brine. This means that when the desalinated solution passes from one stage of ice generation to the second stage in the sequence of stages -53-51-"2-", then the non-azeotropic mixture in this mode passes in the opposite direction (countercurrent), i.e. in the sequence of stages "-34-14- 24-. The electromagnetic valves identified in Fig. 1 with the letter O are all open, and the valves identified with the letter K are all closed.

First, the liquid mixture of refrigerants enters the I-LH" along line 84 and partially boils off (the 1st portion - mainly the low-boiling component boils off) at the lowest temperature, after which it enters the I-LH in the form of a vapor-liquid mixture; along line 85 and further boils off (the 2nd portion), then it, in the form of a vapor-liquid mixture with a large retention of vapor of a low-boiling component, flows along line 65 into the I-LHz, in which the completely hard-boiling component boils off, and then the vapor mixture is removed from the I along line 66 -LHz, passes, heating up, through the heat exchanger 48 and the line 88 to the suction of the compressor 46.

In the mode of concentration, the VOK works basically in a similar way, but it also has distinctions due to the particularly high viscosity of fruit and vegetable and other sugar-containing raw materials at the final stage of concentration. The initial fruit juice (for example, apple juice) is fed by the pump 4 to the filter 5, in which the juice is filtered from particles of suspended substances. Then the juice is cooled in the preliminary heat exchanger 7 to 3-57C and sent through the pipeline 70 to the mixing tank 35, in which it is mixed with ice moved by the screw 27 to the right from all stages of ice generation into this tank.

Turbulization in the tank 35 of the ice-brine suspension ensures its selection together with the ice by the pump 38 and its delivery along the line 74 to the lower part of the separation and washing column SPK. The operation of the SPK in the concentration mode is no different from the operation of the same device in the desalination mode, already described earlier. From the SPK, the juice is filtered through the filter grate 40 and along the line 75 is returned to the irrigation of the upper part of the ice, moved by the auger 27 to the right between the stage 71 and the tank 35. This juice, which has a lower concentration compared to the concentrate film on the ice, pre-washes this ice before by its progress into tank 35 and then flows down the slope to the left and down through the perforation of the bottom of the screw housing 27 into the capacity-crystallizer of the 1st stage Kree, mixing in it with the concentrate of the 1st stage and suddenly increasing its concentration to approximately 2595 according to the law of the mixing crystallizer .

From the bottom of the Kri, the concentrate of the 1st stage is taken by the pump 15 and fed through the line 17 into the pipe space of the 1st stage of the evaporator-ice generator I-Lhi. When moving down the tubes, this concentrate is cooled due to the heat of vaporization of the refrigerant boiling in the intertube space, partially freezes and, together with ice crystals, flows from the lower part of the I-LGi to the auger 27 and then through its bottom perforation of the housing 28 in the Kree. In the capacity-crystallizer of the 2nd stage Kr», the concentrate of the 1st stage enters through the line 18, flows onto the ice mass, which is moved by the turns of the screw 29 in the interval! between Kr» and Kr, washing the ice from the film of concentrate of the 2nd degree. In the devices of the 2nd stage of ice generation I-LH"-Kr" the processes take place similarly to the processes of the 1st stage I-LHi-Kri, but at a higher concentration (35-g4095). Approximately 88-9295 of water from the source juice is extracted in stages 1 and 2.

In step C, the concentrate of the 2nd degree enters through line 21, flows onto the ice mass, which is moved by the turns of the screw 29a to the right in the interval between Krz and Kr, washing the ice from the film of the concentrate of the 3rd degree. In the devices of the 3rd stage of ice generation I-LHz-Krz, the processes proceed similarly to the processes of the 2nd stage I-LH»-Kr», but at a higher concentration (55-7090). Concentration is carried out at least to the parameters of the eutectic point, which, for example, for a solution of sucrose-dextrose - water has a concentration of 64.995 at a temperature of -17"C, and for grape juice, depending on the grape variety, a concentration of about 6795 at a temperature of about -217C. In this last degrees is extracted at about 1095 water. At such a high concentration and low temperature, the juice concentrate has a high viscosity - more than 800 103 Pa s, which complicates the transport of the concentrate and all other processes with it - mass transfer, heat transfer, turbulence, diffusion, equalization of concentration and temperature gradients , separation of 2 solid phases - ice crystals and sugars, separation and washing of ice crystals from the concentrate. To avoid this difficulty, that is, to reduce the viscosity of the turbulized and transported concentrate in the I-LHz-Krz tandem in the case of formation in the last stage of ice generation and the growth of ice crystals from highly viscous concentrates, and equally and simultaneously with ice and the generation and growth of the second solid phase - for example, crystals of salts, sugars, etc., which crystallize at the eutectic point, in the last stage, the concentrate of the desalinated (concentrating) solution is frozen in a mixture with an intermediate low-viscosity at temperatures from -107С to -302С to reduce its viscosity (viscosity no more than 1 103 Pa s) by means of transport.

Liquids immiscible with water are used as a transport medium - for example, organosilicon liquid (silicone), underheated or boiling refrigerants, for example, Freon 11, carbon dioxide, etc. or gases, such as nitrogen, carbon dioxide vapors, sulfur dioxide, etc., with which the freezable concentrate turbulently recirculates in the process of generating ice crystals (and crystals of another solid phase) and in the process of growth of these aforementioned crystals. Silicon-organic liquid (silicone) is used in the case of concentration of technical solutions (for example, rocket fuel - hydrazine). Refrigerants (F11, 134a, 142c, etc.) are used in the case of drinking water production. Carbon dioxide and sulfur dioxide are allowed by the Ministry of Health to be used in the production of concentrates from fruit juices and wine products. Sulfur dioxide is used by the winemaking technologist to prevent the oxidation process of grape must. In case of adaptation of carbon dioxide

The 3rd stage of crystal generation and growth can be separated from the first 2 stages and not have a common screw with them (which may be appropriate in some devices) due to the high pressure of carbon dioxide and the small size of the 3rd stage devices. The current application decision also applies to this partial case.

The volume fraction "c" of the transport medium, which circulates together with the concentrated solution (juice concentrate) in the I-LHz-Krz tandem, depends on the viscosity of the dispersed phase pd - a specific solution (juice concentrate) - and the viscosity of the solid phase pe - of the transport medium - and is suitable in the range o-0.6-0.8 with such a calculation that the viscosity of the mixture of solutions and media does not exaggerate the upper value of its transportability, equal to approximately

Chsumish--10 103Pa p. For example, the viscosity of a mixture of sugar solution (T-202C, concentration - 6095, viscosity of this dispersed phase pde800 103Pa s) and liquid Freon 11 (T-202C, viscosity of this solid phase ps-0.685 103Pa s) at o-0.4 according to the formula of the Bachinsky equation

Chsumishi-(Yai1-030111--41 Botd/(Yad--pe)1-(0.685 103/(1-0.431(11--11.5 0.4 800 1033/1800 103--0.685 103)Ц-1 ,82 103Pa b.

In the concentration mode, the lid 32 is pressed hermetically to the window 31, which allows (see fig. 1 and 2) to maintain the level of the suspension above the level of the lower forming turns of the screw 29a by 1/4 of its diameter with the help of the liquid phase level regulator 57. This reception prevents the holes of the bottom of the auger body from being clogged with ice and ensures "draining" in the flow together with the saturated concentrate and small but heavy sugar crystals in the Krz.

When the level is less than 1/4 of the auger diameter, the larger right side of the bottom of the auger will be drained and smeared with ice; when this level is more than 1/4 of the diameter of the auger, the effect of washing the ice mass moving to the right from the concentrate film due to irrigation of this ice with liquid from line 21 is reduced.

With the help of the pulsation compressor 58, the circulation of the carrier gas, which turbulates the liquid thick phase, is ensured both in the tubes of the evaporator-ice generator I-LHz and in the Krz crystallizer.

From the lower part of the Krz, the concentrate is removed via a line 24 with the help of the pump 20, is separated from the transport medium in the separator 70 and is removed from the VOK(a) along the line 72 as a product. The recirculation concentrate is returned to Krz on line 71.

In the juice concentration mode, the liquid mixture of refrigerants first enters the I-LHz along line 87 and partially boils (the 1st portion - mainly the low-boiling component boils) at the lowest temperature, after which it enters the I-LH»o in the form of a vapor-liquid mixture along line 67 and further boils (the 2nd portion), then it, in the form of a vapor-liquid mixture with a large retention of vapor of a low-boiling component, flows along line 85 into the I-LH', in which all the high-boiling component boils off, and then the mixture of vapors is diverted along line 86 I-LH passes, being heated, through the heat exchanger 48 and the line 88 on the suction of the compressor 46. The non-azeotropic mixture in this mode passes in the sequence of stages "-14-24-34-, and the concentrated food liquid (fruit juices, except grape juice / according to juice - see below/) passes from one stage of ice generation to the second stage in the sequence of stages -51-32-53-".

When working on apple juice, for example, the mode of operation of the refrigerating machine is as follows: - in the evaporators, during its movement from I-LHz to I-LHi, the non-azeotropic mixture of refrigerants boils at a variable temperature, from minus 217"C to minus 9"C, while the boiling pressure of the mixture is constant and is equal to 469.3 kPa (the partial boiling pressure of F22 is equal to 382 kPa, the partial boiling pressure of F142 is equal to 87.3 kPa); - in the refrigerant condenser - ice melter 45 non-azeotropic mixture of refrigerants enriched

F22 condenses practically at a constant temperature of 8"C and a constant pressure of 1.24 MPa (the partial pressure of condensation of F22 is equal to 641 MTkPa); - in an additional condenser (air) 47 from a non-azeotropic mixture of refrigerants at a constant pressure of 1.24 MPa, practically only F142b condenses (at to its partial pressure of 601.2 kPa).

The concentration of a non-azeotropic mixture of refrigerants is determined by calculating the product of the mass fraction of the low-boiling component (in our example F22) and the heat of its vaporization is equal to the heat of the ice melting process. Such ratios of components in the mixture are determined by the amount of ice we have. If F22 is greater than in the specified ratio, then a sufficient low-boiling component will not be condensed in the condenser-melter 45, and for its condensation in the additional condenser 47, the pressure must be increased (this is an overrun of work). If F22 is less than in the specified ratio, then in order to melt all the ice in the condenser-melter 45, it is necessary to send an increased amount of the hard-boiling component (F142v) into it, which will condense all the same at the same pressure and the same temperature, at which it condenses in the air additional condenser 47, that is, in the condenser-melter 45 there will be a high temperature difference during heat transfer, which increases irreversibility (this is an overrun of work).

In addition, at a high temperature in the condenser-melter 45, the operation of the SPK 36 becomes unstable, the washing water flowing down into the SPK becomes too heated, which leads to the melting of a particle of ice even in the process of washing it from the concentrate.

The concentration of the mixture is different for different VOK modes. For example, when concentrating apple juice with an initial concentration of dry substances of 1395 to a final concentration of 4095, the optimal ratio

Ff22:F142v will be 61.5:38.5. When concentrating the same juice with an initial concentration of dry substances of 13905 to a final concentration of dye - flavoring agent of 6095, the optimal ratio of Ф22:Ф142v will be 66.7:34.3.

When concentrating grape juice, VOK works in the same sequence of steps as for the desalination mode, that is, the solution goes from one stage of ice generation to the second stage in the sequence of stages -»3-51-»2-». This is explained by the fact that, first of all, the tartaric acid salts must be removed from the grape juice, which crystallize when the juice is cooled to temperatures of 27--27"Сb. In this case, these salts are deposited in the Krz and removed from the VOK(a) through the separator of the transport medium 70.

In the current method, transferring 3-595 from the original solution to ice and dumping this heavy-water ice makes it possible to obtain light drinking water that has a beneficial biological and medical effect.

Mixing the initial solution with ice after the ice is released from the first stage of ice generation and before it is submitted to separation and washing allows to increase the temperature of the suspension, reduce the concentration of brine (concentrate on the surface of ice crystals), ultimately reduce the viscosity of the brine (concentrate) and improve the efficiency of the operation separation and washing of ice from brine (concentrate).

The use as a refrigerant of a non-azeotropic mixture of refrigerants, for example Ф22-Ф142в, which is introduced countercurrently with the flow of the desalinated solution into the last step of the desalinated or concentrated solution of the ice generation stage and removed from the first step of the desalinated or concentrated solution of the ice generation stage (which is constructively achieved by the fact that the inputs of liquid refrigerant in the evaporator-ice generators and the refrigerant exits from them pass successively through the stages of desalination and concentration of solutions countercurrently with the flow of the dewatered solution), allows, from the point of view, to maintain the variable boiling temperature of refrigerants in all I-LHs, which coincides in terms of its growth rate with the growth of the freezing temperature of the concentrated solution (the number in the direction of its entrance into the VOK), maintain a small temperature difference during heat transfer of the order of 3.5"C, which satisfies the condition that the inner surface of the evaporator tubes is not frozen by ice. Establishing the rule for calculating the concentration of non-azeotropic mixture of refrigerants allows to reduce costs of work on desalination (concentration). Freezing in the last stage of the concentrate of the desalinated (concentrating) solution in a mixture with an intermediate low-viscosity transport medium at temperatures from -107C to -30"C reduces the total viscosity of the suspension, which ensures the process of ice crystallization to zvtectic concentrations (with the precipitation of the second solid phase - crystals of salts or other substances, for example sugars).That is, this acceptance allows you to remove the limitation of reaching the extreme degrees of concentration of the original, for example, food liquid (juices, milk, wine products, vinegar, beer, etc.)

The inclination of the evaporators - ice generators to the crystallizers at an angle of 15-30" simplifies operation in case of personnel errors.

The inclination of the auger(s) at an angle of 10-20" to the horizontal reduces the salinity of the ice as it moves through the auger from left to right (according to the diagram), which will then facilitate the washing of the ice in the separation-washing column.

The presence of a bent visor in the SPK and a straight cross-section of the column for rolling ice and changing its direction of movement to 1807 in an adjacent chamber, in which an irrigation condenser of the refrigerant-ice melter is built-in, ensuring the movement of ice without pressing it, allows to simplify the design of the SPK (no mechanical device), and the main thing is to forcibly feed ice into the condenser of the refrigerant-ice melter under the pressure of the pump 38, which creates the effect of pressing the ice to the surface of the condenser-melter, which increases the coefficient of heat transfer from the side of the melting ice to the wall of the tubes of the condenser-melter. Namely, this external heat transfer coefficient is the main thermal resistance that reduces the overall heat transfer coefficient in this device.

The presence of a removable window located in the rear cross-section of the auger housing in the desalination mode of the initial solution in the desalination mode of the auger housing ensures the precipitation and discharge of heavy water ice from

VOK and, as a result, the production of light water.

The presence in the same capacity-crystallizer when working in the concentration mode of the liquid phase level regulator, which maintains the suspension level above the level of the lower forming screw by 1/4 of its diameter, ensures the separation of two types of crystals - heavy crystals of salt (sugars) that settle during flooding the lower edge of the screw 29a and then fall into the Krz crystallizer capacity, and large crystals (about 200 μm) of ice that move through the screw 29a to the right; The presence between the exit of the suspension from the capacity-crystallizer Krz and the entrance to the pipe space of the evaporator-ice generator I-LHz of the recirculation pulsation compressor contributes to the turbulence of the suspension with gas (transport medium) during its movement along the path of this tandem, cleans the perforation of the bottom of the auger housing 29a, which in total contributes implementation of the process in this tandem. The sum of the declared acceptances in conjunction ensures the universality of the work of the VOK - on any raw water raw material (salt, food), with any degree of dehydration, with the production of any concentrates, which significantly expands the scope of its adaptation (this is especially appropriate in new freezing technologies for the production of sugar and vodka /instead of the energy-wasting evaporation currently in use/, dissolved fruit and vegetable powders, concentrates and powders from thermolabile raw materials /which do not "tolerate" heating processes/ of the pharmaceutical and perfume industry).

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Claims (4)

1. The method of processing aqueous solutions by multi-stage freezing, which includes multi-stage freezing of ice from the aqueous solution being processed with the help of a boiling refrigerant, with separate recirculation processes of ice generation and ice crystal growth in each stage and with successive dehydration of the solution with an increase in its concentration, separation and washing of ice from concentrated brine (concentrate) and ice melting due to the condensation of the refrigerant to obtain desalinated melt water and brine (concentrate) of the required concentration, which differs in that in the first stage no more than 30% of the original solution and this ice are converted into ice discharged as enriched with heavy water, and the remaining initial solution is mixed with ice after it leaves the first stage of ice generation and before it is submitted to separation and washing; as a refrigerant that removes the heat of ice generation during its boiling, a non-azeotropic mixture of refrigerants, such as F22-F142b, is used, which is introduced countercurrently to the flow of the solution into the last stage of ice generation in the course of the solution and removed from the first stage of the solution in the course of ice generation; in the case of the formation in the last stage of ice generation and the growth of ice crystals of highly viscous concentrates, which crystallizes at the eutectic point, in the last stage, to reduce its viscosity, the concentrate solution is frozen in a mixture with an intermediate low-viscosity one at temperatures from -107C to -30" C (viscosity no more than 1-103 Pas) as a transport medium. 2. The method of processing aqueous solutions by multi-stage freezing according to claim 1, which differs in that the concentration of a non-azeotropic mixture of refrigerants is determined by calculating the product of the mass fraction of a low-boiling component, such as F22, by the heat of its vaporization equal to the heat of the ice melting process. 3. The method of processing aqueous solutions by multi-stage freezing according to claim 1, which differs in that liquids immiscible with water, such as organosilicon liquid (silicone), unheated or boiling refrigerants, such as Freon 11, carbon dioxide, etc., are used as a transport medium. or gases, such as nitrogen, vapors of carbon dioxide, sulfur dioxide, etc., with which the frozen concentrate turbulently recirculates in the process of generating ice crystals and in the process of their growth. 4. A multi-stage freezing device for processing aqueous solutions, containing stages, each of which consists of an evaporator-ice generator for generating ice and a separately located capacity-crystallizer for the growth of ice crystals below it, a screw located between the evaporator-ice generators and the capacity-crystallizers of ice for transporting and removing ice from the stages of ice generation and growth, recirculation pumps, a separation and washing column, rectangular in plan, for separating and washing ice from brine or concentrate, and a refrigeration unit consisting of a compressor, a condenser, an additional condenser, evaporators, located in the inter-tube spaces of ice generators, receivers and throttle valves, which is distinguished by the fact that the bodies of the evaporators - ice generators are inclined to the crystallizer capacities at an angle of 15-30"; the auger body from the side from which the ice is delivered to the separation and washing column, with connected to the inlet of the mixing tank and lift and, the auger body is inclined at an angle of 10-20" to the horizontal, and the part of the auger is made removable with left or right winding of turns, and has a slotted connection with the fixed part of the auger, while a removable window with a hermetic cover is installed on the end of the removable part of the auger , the separation and washing column has in its upper part on one side a bent visor, which forms with the upper edge of the column on its opposite side a parallel passage with the cross section of the column for rolling over the ice and changing the direction of its movement by 180" into the adjacent chamber, which has a built-in irrigation condenser of refrigerant-ice melter; the liquid refrigerant inputs to the evaporators-ice generators and the refrigerant outputs from them pass sequentially through the degrees of desalination of the solutions in a countercurrent flow with the flow of the dehydrated solution.