JP2005201546A - Freeze concentration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a conventional freeze concentration system is large-scaled and its processing speed is low. <P>SOLUTION: A cooler 2 as a component of a freezer 200 is mounted on an upper part of a raw water tank 20 filled with the raw water 21, and a slider 444 with a grating 44-a is mounted between the raw water tank 20 and the cooler 2. The ice 22 produced in the cooler 2 is temporarily separated, and transferred to a recovering tank 40 through the grating 44-1 and the slider 44. On the other hand, the raw water 21 sprayed to the cooler 2 flows down in the cooler 2, and then returned to the raw water tank 20 through the grating 44-a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aqueous solution dissolved in water, such as saline solution, glucose solution, juice, milk, drainage solution, or mixed water containing particles that do not dissolve in water (for example, water mixed with fine polyethylene particles) ) Is separated into dilute water and concentrated water using the freeze concentration phenomenon.

The use of the freeze concentration phenomenon to separate dilute water and concentrated water and industrially use them effectively is described in the following documents.
"Falling film type freeze concentrator" Freezing, Vol. 78, No. 904 (February 2003), P49-P54

  The conventional freeze concentration system separates the raw water from the diluted water and the concentrated water while freezing the thick water around the pipe. It takes time for concentration and separation, and the number of tanks increases in the system. It was a big deal. This will be described below with reference to FIGS.

  In this conventional freeze concentration system, the raw water 21 is flowed around the coiled ice-making cooler 2 in the form of a falling liquid film to freeze it, and the raw water is diluted while thickly condensing around the cooler 2. 41 and concentrated liquid 21-a, which is called a falling liquid film type ice-on-coil freeze-concentrated system. The main components are a refrigerator 1, a coil-shaped ice-making cooler 2, a heat exchanger 1-a, pipes 3 and 4, a pump 5 in a receiving tank 20-a, and a raw water 21. The raw water circulation section 200 including the stored raw water tank 20, the pump 23, the pipe 25, and the sprinkler 26, the recovery tank 40 for storing the recovered liquid 41, the radiator 45, and the heat exchangers 49 and 50 are thermally connected. The cooling heat utilization unit 300 is composed of pipes 46 and 47 and a pump 48.

  The pipes 3 and 4 of the refrigeration apparatus 100 are filled with an antifreeze liquid (ethylene glycol or the like), and by driving the pump 5, cold heat generated in the refrigerator 1 is passed through the heat exchanger 1-a. , And supplied to the cooler 2. On the other hand, when the pump 23 is driven, the raw water 21 in the raw water tank 20 flows from the sprinkler 26 to the outer surface of the coil-shaped cooler 2 through the pipe 24, the valve 37, and the pipe 25.

  FIG. 7 shows an initial state in which the raw water 21 starts to flow around the cooler 2. For this reason, no ice grows around the cooler 2.

  FIG. 8 shows a state in which a frozen body (ice or the like) 22 is thickly frozen around the cooler 2 as time passes. In this state, the raw water 21 in the raw water tank 20 is reduced. .

  The operation of freeze concentration uses nighttime electric power or the like to drive the raw water 21 in the raw water tank 20 to the cooler 2 from the sprinkler 26 by driving the pump 23 at night, and then receives it in the liquid receiving tank 20-a. Thereafter, the pipe 53 connected to the lower part is returned to the raw water tank 20 through the valve 57 and the pipe 55. At this time, the valve 56 between the pipes 54 connecting the collection tank 40 and the pipes 53 is closed.

  As shown in FIG. 8, when the freeze concentration operation is completed, a frozen body 22 that is separated from the solute contained in the raw water 21 and is close to pure water freezes thickly around the cooler 2. For this reason, the liquid 21 in the raw | natural water tank 20 turns into the concentrate 21-a. The concentrated liquid 21-a is discharged to the outside by opening the valve 31 of the pipe 30 part. When the raw water 21 is drained or the like, the concentrated liquid 21-a is discharged and processed outside. However, since the amount of the concentrated liquid 21-a is reduced by being concentrated, the processing amount can be reduced and the processing work is easy. This produces the advantage. Further, since it is concentrated in the case of juice or the like, it is effectively used as a high-quality product with improved added value.

  A frozen body (ice or the like) 22 that is thickly frozen around the cooler 2 uses its cold energy for process cooling and air conditioning in the cold heat utilization unit 300 while defrosting it by the method shown in FIG. 8 during the daytime. Therefore, the valve 57 is closed and the valve 56 is opened. On the other hand, the pump 23 is driven to supply the recovered liquid 41 accumulated in the recovery tank 40 around the frozen body 22 of the cooler 2 from the pipe 25 through the sprinkler 26 via the pipe 35 and the valve 36. Thereafter, the recovered liquid 41 is returned from the liquid receiving tank 20-a into the recovery tank 40 through the pipe 53, the valve 56, and the pipe 54. Therefore, the valve 37 in the pipe 24 part is closed and the valve 36 in the pipe 35 part is opened. Since the recovered liquid 41 that has been frozen and accumulated in the recovery tank 40 is at a low temperature, the pump 48 is driven to transfer the heat medium (water, etc.) in the pipes 46 and 47 to the heat exchanger 50. By transporting from the side to the heat exchanger 49 side, cold heat is generated from the radiator 45. This cold energy is used for air conditioning and process cooling.

  In this conventional system, the cooler 2 has a coil shape, and ice is thickly formed around it to perform the freeze concentration operation. Therefore, it is necessary to increase the coil interval. It is necessary to always secure a large private space within a. Further, the nighttime freeze concentration operation shown in FIG. 7 and the daytime ice-melting / heating use operation shown in FIG. 8 also require the use of the liquid receiving tank 20-a, and are newly produced by the factory process during the daytime. The raw water 21 or the wastewater generated during the day cannot be appropriately put into the liquid receiving tank 20-a for use. For this reason, the raw water 21 produced during the day needs to be stored after storing a separate auxiliary tank 32 through the pump 27, pipe 28 and valve 29. For this reason, there is a problem that the arrangement space of the system becomes large. In addition, when using heat during the day, it is necessary to drive not only the pump 48 of the heat utilization unit 300 but also the pump 23 of the raw water circulation unit 200, which is not preferable in terms of energy saving.

  In order to solve the above problems, (1) the cooler constituting the refrigeration apparatus is formed into a flat plate shape, and raw water is allowed to flow through the flat plate cooler to freeze, and then the cooler is temporarily heated to deice. (2) Next, the raw water flowing down the cooler and the crushed ice separated from the cooler are separated, and the flowed raw water is transferred to the raw water tank and the crushed ice is transferred to the recovery tank of the heat utilization section. A mechanism is provided. (3) When a cooler is provided in the upper part of the raw water tank by adopting such a configuration, the raw water tank also serves as a liquid receiving tank, and the liquid receiving tank is omitted. (4) If a cooler cannot be installed in the upper part of the raw water tank, a small liquid receiving tank is provided, and a mechanism for separating the raw water and crushed ice is provided in this upper part, and a cooler is provided in the upper part of this mechanism. Set up.

  According to the present invention, (1) during the daytime heat utilization time period, it is only necessary to melt the crushed ice stored in the recovery tank and supply this cold heat to the heat radiating section, and it is sufficient to drive only the heat utilization section pump. In addition, it is not necessary to transport raw water from the raw water tank to the cooling unit via the sprinkler, and the pump associated therewith can be stopped, thus saving energy. (2) Since the concentrated liquid in the raw water tank is discharged and used, it is emptied, and then raw water or wastewater generated from the daytime production process can be directly put into the raw water tank for storage, so an auxiliary tank is unnecessary. Become. (3) Since the frozen body crystallized in the cooler is appropriately deiced and dynamically frozen and deiced, the processing speed of the system is increased and it is useful for practical use.

  Embodiments of the present invention will be described below.

  1 and 2 are configuration diagrams of an embodiment of the present invention. FIG. 1 shows a state at the beginning of the start of freeze concentration, and FIG. 2 shows a state before the end of freeze concentration. In this embodiment, a plate-like cooler 2 is disposed on the upper part of the raw water tank 20, and this cooler 2 is composed of a refrigerator 1 by pipes 3 and 4, a pump 5 and a heat exchanger 1-a. And is thermally coupled. Further, between the raw water tank 20 and the cooler 2, there is provided an inclined eye plate 44-a through which the raw water 21 and the concentrated liquid 21-a can pass, and a slider 44 is attached to the lower part thereof. . The pump 5 is driven to supply a minus temperature refrigerant generated in the refrigerator 1 into the cooler 2 through the pipes 3 and 4 and the heat exchanger 1-a. On the other hand, the pump 23 is driven, and the raw water 21 in the raw water tank 20 flows through the sprinkler 26 via the pipes 24 and 25 to the outer surface of the cooler 2 in the form of a falling liquid film. This falling liquid film flow gradually begins to freeze around the cooler 2 due to the cold heat of the minus temperature from the cooler 2. By this process, the frozen body (ice) 22 frozen on the outer surface of the cooler 2 becomes purified ice, flows down the cooler 2 and falls to the lower part thereof, passes through the eye plate 44-a, and the lower part thereof. The liquid (water) 21 falling into the raw water tank 20 becomes concentrated water with a large amount of solute. If the frozen body (ice) 22 grows around the cooler 2 for a certain time, the refrigerator 1 is stopped and the supply of cold heat to the cooler 2 is stopped. If the pump 5 is continuously driven, the heat of the outside air is gradually supplied to the cooler 2, and the cooler 2 rises to a plus temperature. As a result, the portion where the frozen body (ice) 22 is in contact with the cooler 2 is melted, whereby the frozen body (ice) 22 falls to the lower portion and becomes crushed ice. The crushed ice 22-a slides on the tilted eye plate 44-a, slides on the slider 44, and falls into the collection tank 40 to be stored.

  When the ice making / deicing operation by the cooler 2 proceeds, as shown in FIG. 2, the raw water 21 in the raw water tank 20 becomes concentrated water containing a large amount of solute, and the amount is as shown in FIG. 1 than the raw water 21 in the initial state. The concentrated raw water 21 is discharged from the pipe 30 to the outside by opening the valve 31. On the other hand, the amount of crushed ice 22-a stored in the collection tank 40 increases. The crushed ice 22-a is close to pure water, but the cold heat of the crushed ice 22-a is melted and used in the cold heat utilization unit 300. That is, when the pump 48 is driven and the heat medium (antifreeze liquid such as ethylene glycol) in the pipes 46 and 47 is circulated through the heat exchanger 49 and the heat exchanger 50, the crushed ice 22-a is gradually melted and diluted. It becomes the liquid 41. The cold heat generated at this time is cooled by the radiator 45 and used for air conditioning and process cooling. The melted diluted recovered liquid 41 is transported to a desired place through the pipe 42 by opening the valve 43 and is effectively used.

  Such heat utilization operation is performed in the daytime, but only the pump 48 may be driven during the daytime, and the pump 23 of the raw water circulation unit 200 and the pump 5 of the refrigeration apparatus 100 unit may be stopped. It is extremely energy saving. Further, if the concentrated raw water 21-a in the raw water tank 20 is discharged from the pipe 30, it is empty in the daytime. Therefore, the pump 27 is driven and the raw water tank is connected via the pipe 28 and the valve 29. The raw water 21 produced during the daytime can be directly fed into the inside 20 and can stand by until the freeze concentration operation at night. That is, the auxiliary tank 32 of FIGS. 7 and 8 of the conventional system is not necessary.

  Further, in the nighttime freeze concentration operation, the raw water tank 20 also functions as a liquid receiving tank, and therefore the liquid receiving tank 20-a shown in FIGS. 7 and 8 is not necessary.

  In this embodiment, in order to promote the deicing operation, the refrigerator 1 is stopped, the middle of the pipe 3 is branched and thermally connected to another heat exchanger (not shown), and this heat exchange is performed. When the heat is temporarily given to the cooler and this heat is supplied to the cooler 2, the effect of dehydrating the frozen body (ice or the like) 22 is enhanced.

  FIG. 3 is a block diagram of another embodiment of the present invention. This is an embodiment effective in the case where the cooler 2 cannot be provided at the upper part of the raw water tank 20 and the cooler 2 must be provided at a location farther than that. A small liquid receiving tank 20-a is provided at the lower part of the eye plate 44-a connected to the slider 44, and the liquid receiving tank 20-a and the raw water tank 20 are connected by a pipe 51. If necessary, a valve 52 may be provided in the pipe 51 to adjust the return amount. At night, the raw water 21 in the raw water tank 20 is supplied to the outer surface of the cooler 2 disposed on the top of the eye plate 44-a by driving the pump 23 to perform the freeze concentration operation. The raw water 21 gradually decreases from the raw water tank 20 while circulating through the sprinkler 26, the cooler 2, the eye plate 44-a, the liquid receiving tank 20-a, and the pipe 51. On the other hand, by the deicing operation, the crushed ice 22-a transferred into the collection tank 40 via the eye plate 44-a and the slider 44 gradually increases. Thus, the crushed ice 22-a stored in the recovery tank 40 is melted in the daytime, and the cold energy is used for air conditioning and process cooling.

  FIG. 4 is a block diagram of the modified embodiment of FIG. In this embodiment, an eye plate 44-a is provided in the middle of the slider 44, and a liquid receiving tank 20-a is provided below the eye plate 44-a. Even in such a configuration, the same effect as in FIG. 3 is obtained.

  FIG. 5 is a block diagram of the modified embodiment of FIG. This is an example in the case where the cooler 2 is disposed above the collection tank 40. An inclined pan 44-a and a slider 44 are provided at the lower part of the cooler 2, and a liquid receiving tank 20-a is provided at the lower part of the pan 44-a so that the concentrated liquid 21-a can be stored. . Also in such an example, a pipe 51 with a valve 52 may be provided as in FIG. 4 to supply the raw water 21 into the raw water tank 20. However, when the raw water tank 20 and the recovery tank 40 can be installed close to each other as shown in FIG. 5, a wall 20-b between the raw water tank 20 and the recovery tank 40 is provided integrally, and the wall 20-b is provided on the wall 20-b. An opening 51-a may be provided, and the concentrated liquid 21-a in the liquid receiving tank 20-a may be returned to the raw water tank 20 through the opening 51-a. In this way, the device is simplified.

  FIG. 6 is a block diagram of the modified embodiment of FIG. In this embodiment, instead of the liquid receiving tank 20-a and the pipe 51 of FIG. 3, a raw water return plate 44-b is provided with a reverse gradient with respect to the slider 44. In this way, the liquid receiving tank 20-a and the pipe 51 can be omitted, and the thin pipe 51 need not be used, and a large amount of concentrated water 21-a can be returned to the raw water tank 20. Further, in this embodiment, the refrigeration apparatus 100 is a direct expansion system, and it is not necessary to flow antifreeze liquid (ethylene glycol or the like) necessary for indirect heat exchange through the pipes 3 and 4, and the pump 5 is also unnecessary. For this reason, the compressor 6, the condenser 7, and the pressure reducing mechanism (expansion valve) 8 are connected between the pipes 3 and 4 using the pipes 11 and 12. The refrigerant (such as chlorofluorocarbon) adiabatically compressed by the compressor 6 passes through the pipe 11 and enters the condenser 7 where the latent heat of condensation is released and liquefied. After that, adiabatic expansion occurs while passing through the pipe 12 and the valve 9 and the pressure reducing mechanism (expansion valve) 8, and the temperature is lowered. As a result, the cooler 2 is cooled to a negative temperature, and then enters the compressor 6 through the pipe 3 and repeats the same cycle as before. To release the frozen body (ice) 22 grown around the cooler 2, the valve 9 of the pipe 12 is closed, and the valve 10 of the pipe 13 connecting the pipe 11 and the pipe 4 is temporarily opened. The high-temperature refrigerant adiabatically compressed by the compressor 6 passes through the valve 10 of the pipe 13 and is then directly injected into the cooler 2 from the pipe 4 without passing through the pressure reducing mechanism 8. For this reason, the cooler 2 is temporarily heated, and the frozen body (ice) 22 grown around the cooler 2 is detached to be deiced 22-a and transferred into the recovery tank 40. When this deicing operation is completed, the valve 10 is closed again, the valve 9 is opened, and the original freezing operation is started. According to this system, it can be deiced in a short time.

  A dynamic method in which ice making / deicing operations are repeated using the flat plate cooler of the present invention and an ice-on-coil method in which ice is grown thickly around a conventional coiled cooler. The difference in the ice making amount will be clarified with reference to FIG. 9 and FIG.

  In FIG. 9, the horizontal axis represents time t, and the vertical axis represents dimensionless ice thickness. In both cases, the ice thickness grows parabolically with respect to time t, and the growth rate decreases with time. This is because the ice thickness increases and the thermal resistance of the ice crystal layer increases with time. Even in the case of the flat plate type, if ice is continuously grown on the cooler without performing the deicing operation, a large amount of ice making cannot be expected. For this reason, the dynamic type used in the present invention continues ice making while deicing ice grown in a short time. That is, immediately after the start of ice growth in the vicinity of the origin of the flat curve in FIG. 9, the gradient of the ice thickness (growth rate) with respect to the parabolic time is large and the growth rate is fast. Taking an example of 20 min ice making / 2 min deicing as an example, if the thickness of the grown ice is integrated with respect to time, the integrated ice thickness with respect to time can be remarkably increased as indicated by a dashed line. Such a dynamic type can significantly increase the yield of ice compared to a flat plate type without deicing, and has a high synergistic effect when used in a freeze concentration system.

  FIG. 10 shows the result of FIG. 9 with time t on the horizontal axis and dimensionless ice making on the vertical axis. The present invention is a dynamic type (one-dot chain line) versus a circular pipe type (solid line). Indicates that the ice making amount is remarkably large, and the same ice making amount can be obtained in about half the time of the circular tube type.

Configuration diagram of one embodiment of the present invention The figure which shows the state which freeze concentration advanced in the Example of FIG. Configuration of another embodiment of the present invention FIG. 3 is a block diagram of the modified embodiment of FIG. 4 is a block diagram of the modified embodiment of FIG. FIG. 3 is a block diagram of the modified embodiment of FIG. Configuration diagram of conventional freeze concentration system FIG. 7 is a configuration diagram of the conventional method in FIG. 7 and shows a state after completion of freeze concentration. The figure explaining the effect of the dynamic type freeze concentration system of this invention The figure explaining the effect of the dynamic type freeze concentration system of this invention

Explanation of symbols

1 ………… Refrigerator 1−a ……… Heat exchanger 2 ………… Cooler (flat plate, ice making coil)
3, 4 …… Pipe 5 ………… Pump 6 ………… Compressor 7 ………… Condenser 8 ………… Decompression mechanism (expansion valve)
9, 10 ………… Valve 11, 12, 13 ………… Pipe 20 ……… Raw water tank 20-a …… Receiving tank 21 ……… Raw water 21-a ………… Concentrated liquid 22 ………… Frozen bodies (ice, etc.)
22-a ………… Crush ice 23 ………… Pump 24,25… Pipe 26 ………… Sprinkler 27 ………… Pump 28 ………… Pipe 29 ………… Valve 30 ………… Pipe 31 ………… Valve 32 ………… Auxiliary tank 33 ………… Pipe 34 ………… Valve 35 ………… Pipe 36, 37… Valve 40 ………… Recovery tank 41 ………… Recovered liquid ( Dilute liquid)
42 ………… Pipe 43 ………… Valve 44 ………… Slider 44-a ……… Deck plate (mesh, plate with punch holes)
44-b ………… Raw water return plate 45 ………… Heat radiator 46,47 …… Pipe 48 ………… Pump 49,50 …… Heat exchanger 51 ………… Pipe 51-a ………… Open hole 52 ………… Valve 53, 54, 55 …… Pipe 56, 57 …… Valve 100 ………… Refrigeration equipment 200 ………… Raw water circulation part 300 ………… Cool heat utilization part

Claims (2)

  After freezing the raw water sent from the raw water tank by the cold heat of the refrigerator, a cooler that has the function of removing the ice generated by this, it is installed in the lower part of the cooler, A freeze concentration system comprising a mechanism that can be returned to the raw water tank and separated from the unfrozen raw water and transported to the recovery tank provided with the deicing separately.   A mechanism for separating the unfrozen raw water and deicing between the cooler and the raw water tank and the recovery tank below the cooler, and temporarily receiving the unfrozen raw water and returning it to the raw water tank The freeze concentration system according to claim 1, further comprising a liquid receiving tank that can be used.

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