Sodium phosphate dodecahydrate freezing crystallization system

Abstract

The utility model relates to the technical field of freezing crystallization, and discloses a sodium phosphate dodecahydrate freezing crystallization system which comprises a pre-cooling module, a first freezing crystallization module, a second freezing crystallization module, a solid-liquid separation module and a freezing module which are connected in sequence, the first freezing crystallization module is used for performing primary freezing crystallization on the cooled and pre-cooled stock solution, and the second freezing crystallization module is used for performing secondary freezing crystallization on the stock solution subjected to primary freezing crystallization; the solid-liquid separation module is used for carrying out solid-liquid separation on the crystal mush mixture discharged by the second freezing crystallization module to prepare crystalline sodium phosphate dodecahydrate; the solid-liquid separation module is further used for providing freezing mother liquor for the freezing mother liquor cooler and the first freezing crystallization module, and the freezing module is used for providing freezing liquid for the circulating water cooler and the second freezing crystallization module. The sodium phosphate dodecahydrate crystallization device is low in requirement on feeding concentration, good in material fluctuation resistance and high in sodium phosphate dodecahydrate crystallization purity, and the control difficulty is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of freezing crystallization, in particular to a sodium phosphate dodecahydrate freezing crystallization system. Background Art

[0002] Sodium phosphate is a very important phosphate. Industrial-grade sodium phosphate is used as a water softener and detergent, a metal descaling agent, and a boiler scale inhibitor in industries such as chemical engineering, textile, printing and dyeing, paper making, and power generation.

[0003] In the prior art, at present, the thermal evaporation method is mainly used to treat sodium phosphate wastewater to recover sodium phosphate. The thermal method has poor resistance to material volatility, great control difficulty, low product recovery rate, and a large amount of miscellaneous salts.

[0004] Therefore, how to provide a sodium phosphate dodecahydrate freezing crystallization system to improve the freezing crystallization purity of sodium phosphate dodecahydrate and reduce the control difficulty has become an urgent technical problem to be solved. Summary of the Utility Model

[0005] The technical problem to be solved by the utility model is to provide a sodium phosphate dodecahydrate freezing crystallization system to improve the freezing crystallization purity of sodium phosphate dodecahydrate and reduce the control difficulty.

[0006] To this end, according to the first aspect, an embodiment of the utility model discloses a sodium phosphate dodecahydrate freezing crystallization system, including: a precooling module, a first freezing crystallization module, a second freezing crystallization module, a solid-liquid separation module, and a freezing module connected in sequence;

[0007] Wherein, the precooling module includes a pre-freezing liquid tank, a freezing mother liquor cooler, and a circulating water cooler connected in sequence. The pre-freezing liquid tank is used to store the original liquid to be frozen and crystallized. The freezing mother liquor cooler is used to perform primary cooling and precooling on the original liquid. The circulating water cooler is used to perform secondary cooling and precooling on the original liquid;

[0008] The first freezing crystallization module is connected to the circulating water cooler. The first freezing crystallization module is used to perform primary freezing crystallization on the precooled original liquid. The second freezing crystallization module performs secondary freezing crystallization on the original liquid after the primary freezing crystallization; the solid-liquid separation module is used to perform solid-liquid separation on the crystal slurry mixture discharged from the second freezing crystallization module to obtain crystalline sodium phosphate dodecahydrate; the solid-liquid separation module is also used to provide freezing mother liquor for the freezing mother liquor cooler and the first freezing crystallization module. The freezing module is used to provide freezing liquid for the circulating water cooler and the second freezing crystallization module.

[0009] The present utility model is further configured such that the first freezing crystallization module includes a first freezing crystallizer, a first freezing external cooler, and a first circulation pump that are connected in a circulating sequence. The first freezing crystallizer is connected to the circulating water cooler, and the solid-liquid separation module is used to provide freezing mother liquor to the first freezing external cooler.

[0010] The present utility model is further configured such that a first auxiliary circulation pump for ensuring the heat exchange effect of the first freezing external cooler is connected to the first freezing external cooler.

[0011] The present utility model is further configured such that the second freezing crystallization module includes a second freezing crystallizer, a second freezing external cooler, and a second circulation pump that are connected in a circulating sequence. The second freezing crystallizer is connected to the first freezing crystallization module, and the freezing module is used to provide freezing liquid to the second freezing external cooler.

[0012] The present utility model is further configured such that a second auxiliary circulation pump for ensuring the heat exchange effect of the second freezing external cooler is connected to the second freezing external cooler.

[0013] The present utility model is further configured such that the solid-liquid separation module includes a thickener, a centrifuge, a freezing mother liquor stirrer, and a freezing mother liquor tank that are connected in sequence. A thickening stirrer is provided in the thickener. The freezing mother liquor tank is used to store the freezing mother liquor after solid-liquid separation. A freezing mother liquor pump is connected to the freezing mother liquor tank, and the freezing mother liquor pump is used to pump the freezing mother liquor to the freezing mother liquor cooler and the first freezing crystallization module.

[0014] The present utility model is further configured such that the freezing module includes a freezing water tank, a freezing internal circulation pump, and a freezing unit that are connected in a circulating sequence. The freezing water tank is used to provide freezing liquid to the second freezing crystallization module.

[0015] The present utility model is further configured such that the freezing module further includes a freezing external circulation pump, and the freezing external circulation pump is used to enable the external circulation of the freezing liquid between the freezing water tank and the second freezing crystallization module.

[0016] The present utility model is further configured such that the freezing module further includes a freezing liquid drain pump and a freezing liquid collection tank that are connected to each other. The freezing liquid drain pump is connected to the freezing water tank, and the freezing liquid collection tank is connected to the second freezing crystallization module.

[0017] The utility model has the following beneficial effects: The stock solution is precooled by the precooling module, continuously freeze-crystallized by the first freeze-crystallization module and the second freeze-crystallization module, and the crystal slurry mixture is subjected to solid-liquid separation by the solid-liquid separation module to obtain crystalline sodium phosphate dodecahydrate. Furthermore, a freeze-crystallization system for sodium phosphate dodecahydrate is provided, which has low requirements for the feed concentration, good resistance to material volatility, high crystallization purity of sodium phosphate dodecahydrate, and reduced control difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 is a schematic structural diagram of a freeze-crystallization system for sodium phosphate dodecahydrate disclosed in this embodiment;

[0020] Figure 2 is a schematic structural diagram of the precooling module in a freeze-crystallization system for sodium phosphate dodecahydrate disclosed in this embodiment;

[0021] Figure 3 is a schematic structural diagram of the first freeze-crystallization module in a freeze-crystallization system for sodium phosphate dodecahydrate disclosed in this embodiment;

[0022] Figure 4 is a schematic structural diagram of the second freeze-crystallization module in a freeze-crystallization system for sodium phosphate dodecahydrate disclosed in this embodiment;

[0023] Figure 5 is a schematic structural diagram of the solid-liquid separation module in a freeze-crystallization system for sodium phosphate dodecahydrate disclosed in this embodiment;

[0024] Figure 6 is a schematic structural diagram of the freezing module in a freeze-crystallization system for sodium phosphate dodecahydrate disclosed in this embodiment;

[0025] Figure 7 is a schematic diagram of the operation flow of a freeze-crystallization system for sodium phosphate dodecahydrate disclosed in this embodiment.

[0026] Reference numerals: 10, precooling module; 11, liquid tank before freezing; 12, freezing mother liquor cooler; 13, circulating water cooler; 14, feed pump; 20, first freezing crystallization module; 21, first freezing crystallizer; 22, first freezing external cooler; 23, first circulation pump; 24, first auxiliary circulation pump; 25, transfer pump; 30, second freezing crystallization module; 31, second freezing crystallizer; 32, second freezing external cooler; 33, second circulation pump; 34, second auxiliary circulation pump; 35, discharge pump; 40, solid-liquid separation module; 41, thickener; 411, thickening agitator; 42, centrifuge; 43, freezing mother liquor agitator; 44, freezing mother liquor tank; 45, freezing mother liquor pump; 50, freezing module; 51, freezing water tank; 52, freezing internal circulation pump; 53, freezing unit; 54, freezing external circulation pump; 55, freezing liquid drain pump; 56, freezing liquid collection tank. Detailed implementation manners

[0027] In order to make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0028] In the description of the present utility model, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may also be the communication inside two components. It may be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0029] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present utility model. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In addition, the technical features involved in different implementation manners of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0031] An embodiment of the utility model discloses a sodium phosphate dodecahydrate freezing crystallization system, as Figures 1-7 shown, comprising: a precooling module 10, a first freezing crystallization module 20, a second freezing crystallization module 30, a solid-liquid separation module 40 and a freezing module 50 which are connected in sequence;

[0032] Among them, the precooling module 10 includes a pre-freezing liquid tank 11, a freezing mother liquor cooler 12 and a circulating water cooler 13 connected in sequence. The pre-freezing liquid tank 11 is used for storing the original liquid to be frozen and crystallized. The freezing mother liquor cooler 12 is used for performing primary cooling precooling on the original liquid, and the circulating water cooler 13 is used for performing secondary cooling precooling on the original liquid;

[0033] The first freezing crystallization module 20 is connected to the circulating water cooler 13. The first freezing crystallization module 20 is used for performing primary freezing crystallization on the precooled original liquid, and the second freezing crystallization module 30 performs secondary freezing crystallization on the original liquid after primary freezing crystallization; The solid-liquid separation module 40 is used for performing solid-liquid separation on the crystal slurry mixture discharged from the second freezing crystallization module 30 to obtain crystalline sodium phosphate dodecahydrate; The solid-liquid separation module 40 is also used for providing freezing mother liquor for the freezing mother liquor cooler 12 and the first freezing crystallization module 20, and the freezing module 50 is used for providing freezing liquid for the circulating water cooler 13 and the second freezing crystallization module 30. In this embodiment, the freezing mother liquor cooler 12 is connected to the first freezing external cooler 22. A feed pump 14 for pumping the original liquid is installed between the pre-freezing liquid tank 11 and the freezing mother liquor cooler 12, and the number of the feed pumps 14 is two and they are arranged in parallel.

[0034] It should be noted that the original liquid is precooled by the precooling module 10, the first freezing crystallization module 20 and the second freezing crystallization module 30 perform continuous freezing crystallization on the original liquid, and the solid-liquid separation module 40 performs solid-liquid separation on the crystal slurry mixture to obtain crystalline sodium phosphate dodecahydrate, thereby providing a sodium phosphate dodecahydrate freezing crystallization system, which has a low requirement for the feed concentration, good resistance to material volatility, high crystallization purity of sodium phosphate dodecahydrate, and reduces the control difficulty.

[0035] As Figure 1 and Figure 3 shown, the first freezing crystallization module 20 includes a first freezing crystallizer 21, a first freezing external cooler 22 and a first circulation pump 23 which are connected in a circulating sequence. The first freezing crystallizer 21 is connected to the circulating water cooler 13, and the solid-liquid separation module 40 is used for providing freezing mother liquor for the first freezing external cooler 22. In the specific implementation process, after the original liquid is precooled by the freezing mother liquor cooler 12 and the circulating water cooler 13, it enters the first freezing crystallizer 21, and through the freezing cooling of the freezing mother liquor, the original liquid crystallizes at 30°C.

[0036] It should be noted that by setting the first circulation pump 23, the materials in the first freezing crystallizer 21 can be driven to circulate and cool down to obtain crystalline sodium phosphate dodecahydrate.

[0037] As Figure 1 and Figure 3 shown, a first auxiliary circulation pump 24 for ensuring the heat exchange effect of the first freezing external cooler 22 is connected to the first freezing external cooler 22. In the specific implementation process, the numbers of the first circulation pump 23, the first freezing external cooler 22, and the first auxiliary circulation pump 24 are all set to two, and they correspond one by one, forming a main and a standby to ensure the smooth operation of the system.

[0038] As Figures 1-4 shown, the second freezing crystallization module 30 includes a second freezing crystallizer 31, a second freezing external cooler 32, and a second circulation pump 33 that are connected in sequence and cyclically. The second freezing crystallizer 31 is connected to the first freezing crystallization module 20, and the freezing module 50 is used to provide coolant for the second freezing external cooler 32. In the specific implementation process, the stock solution in the second freezing crystallizer 31 crystallizes at 0°C; a transfer pump 25 is installed between the second freezing crystallizer 31 and the first freezing crystallizer 21, and the number of the transfer pumps 25 is set to two and they are arranged in parallel. It should be noted that by setting the second circulation pump 33, the materials in the second freezing crystallizer 31 can be driven to circulate and cool down to obtain crystalline sodium phosphate dodecahydrate.

[0039] It should be noted that the materials in the second freezing crystallizer 31 are pumped into the thickener 41 by the discharge pump 35. The number of the discharge pumps 35 is set to two and they are arranged in parallel to ensure the normal operation of the system.

[0040] As Figures 1-4 shown, a second auxiliary circulation pump 34 for ensuring the heat exchange effect of the second freezing external cooler 32 is connected to the second freezing external cooler 32. In the specific implementation process, the numbers of the second circulation pump 33, the second freezing external cooler 32, and the second auxiliary circulation pump 34 are all set to two, and they correspond one by one, forming a main and a standby to ensure the smooth operation of the system.

[0041] As Figures 1-5 shown, the solid-liquid separation module 40 includes a thickener 41, a centrifuge 42, a frozen mother liquor stirrer 43, and a frozen mother liquor tank 44 that are connected in sequence. A thickening stirrer 411 is provided in the thickener 41. The frozen mother liquor tank 44 is used to store the frozen mother liquor after solid-liquid separation. A frozen mother liquor pump 45 is connected to the frozen mother liquor tank 44, and the frozen mother liquor pump 45 is used to pump the frozen mother liquor to the frozen mother liquor cooler 12 and the first freezing crystallization module 20. In the specific implementation process, a frozen mother liquor pump 45 is installed between the frozen mother liquor tank 44 and the frozen mother liquor cooler 12, and the frozen mother liquor pump 45 is also connected to the first freezing external cooler 22.

[0042] It should be noted that through the setting of the chilled mother liquor pump 45, the chilled mother liquor in the chilled mother liquor tank 44 is pumped by the chilled mother liquor pump 45 to the chilled mother liquor external cooler and the first chilled external cooler 22 to provide cooling capacity for them.

[0043] As Figure 1 and Figure 6 shown, the refrigeration module 50 includes a refrigeration water tank 51, a refrigeration internal circulation pump 52 and a refrigeration unit 53 that are connected in sequence and circulated. The refrigeration water tank 51 is used to provide refrigerating liquid for the second refrigeration crystallization module 30.

[0044] As Figure 1 and Figure 6 shown, the refrigeration module 50 further includes a refrigeration external circulation pump 54. The refrigeration external circulation pump 54 is used to perform external circulation of the refrigerating liquid between the refrigeration water tank 51 and the second refrigeration crystallization module 30. In the specific implementation process, the refrigeration water tank 51 and the refrigeration external circulation pump 54 are respectively connected to the second refrigeration external cooler 32.

[0045] As Figure 1 and Figure 6 shown, the refrigeration module 50 further includes a refrigerating liquid drain pump 55 and a refrigerating liquid collection tank 56 that are connected to each other. The refrigerating liquid drain pump 55 is connected to the refrigeration water tank 51, and the refrigerating liquid collection tank 56 is connected to the second refrigeration crystallization module 30.

[0046] Working principle: The stock solution is precooled by the precooling module 10, the first refrigeration crystallization module 20 and the second refrigeration crystallization module 30 perform continuous refrigeration crystallization on the stock solution, and the solid-liquid separation module 40 performs solid-liquid separation on the crystal slurry mixture to obtain crystalline sodium phosphate dodecahydrate. Furthermore, a sodium phosphate dodecahydrate refrigeration crystallization system is provided, which has a low requirement for the feed concentration, good resistance to material volatility, high crystallization purity of sodium phosphate dodecahydrate, and reduces the control difficulty.

[0047] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A sodium phosphate dodecahydrate freeze crystallization system, characterized in that, Comprising: A pre-cooling module (10), a first freezing crystallization module (20), a second freezing crystallization module (30), a solid-liquid separation module (40), and a freezing module (50) connected in sequence; Wherein, the pre-cooling module (10) includes a pre-freezing liquid tank (11), a freezing mother liquor cooler (12), and a circulating water cooler (13) connected in sequence. The pre-freezing liquid tank (11) is used to store the original liquid to be frozen and crystallized. The freezing mother liquor cooler (12) is used to perform primary cooling pre-cooling on the original liquid, and the circulating water cooler (13) is used to perform secondary cooling pre-cooling on the original liquid; The first freezing crystallization module (20) is connected to the circulating water cooler (13). The first freezing crystallization module (20) is used to perform primary freezing crystallization on the pre-cooled original liquid. The second freezing crystallization module (30) performs secondary freezing crystallization on the original liquid after primary freezing crystallization. The solid-liquid separation module (40) is used to perform solid-liquid separation on the crystal slurry mixture discharged from the second freezing crystallization module (30) to obtain crystalline sodium phosphate dodecahydrate. The solid-liquid separation module (40) is also used to provide freezing mother liquor to the freezing mother liquor cooler (12) and the first freezing crystallization module (20). The freezing module (50) is used to provide freezing liquid to the circulating water cooler (13) and the second freezing crystallization module (30).

2. The sodium phosphate dodecahydrate freeze crystallization system according to claim 1, characterized in that, The first freezing crystallization module (20) includes a first freezing crystallizer (21), a first freezing external cooler (22), and a first circulation pump (23) connected in a circulating sequence. The first freezing crystallizer (21) is connected to the circulating water cooler (13). The solid-liquid separation module (40) is used to provide freezing mother liquor to the first freezing external cooler (22).

3. The sodium phosphate dodecahydrate freeze crystallization system according to claim 2, wherein A first auxiliary circulation pump (24) is connected to the first freezing external cooler (22) to ensure the heat exchange effect of the first freezing external cooler (22).

4. The sodium phosphate dodecahydrate freeze crystallization system according to claim 1, characterized in that, The second freezing crystallization module (30) includes a second freezing crystallizer (31), a second freezing external cooler (32), and a second circulation pump (33) connected in a circulating sequence. The second freezing crystallizer (31) is connected to the first freezing crystallization module (20). The freezing module (50) is used to provide freezing liquid to the second freezing external cooler (32).

5. The sodium phosphate dodecahydrate freeze crystallization system according to claim 4, characterized in that, A second auxiliary circulation pump (34) is connected to the second freezing external cooler (32) to ensure the heat exchange effect of the second freezing external cooler (32).

6. The sodium phosphate dodecahydrate freeze crystallization system according to claim 1, characterized in that, The solid-liquid separation module (40) includes a thickener (41), a centrifuge (42), a freezing mother liquor stirrer (43), and a freezing mother liquor tank (44) connected in sequence. A thickening stirrer (411) is provided in the thickener (41). The freezing mother liquor tank (44) is used to store the freezing mother liquor after solid-liquid separation. A freezing mother liquor pump (45) is connected to the freezing mother liquor tank (44). The freezing mother liquor pump (45) is used to pump the freezing mother liquor to the freezing mother liquor cooler (12) and the first freezing crystallization module (20).

7. The sodium phosphate dodecahydrate freeze crystallization system according to any one of claims 1-6, characterized in that, The refrigeration module (50) includes a refrigeration water tank (51), a refrigeration internal circulation pump (52), and a refrigeration unit (53) that are connected in a cyclic sequence. The refrigeration water tank (51) is used to provide refrigerant liquid to the second refrigeration crystallization module (30).

8. The sodium phosphate dodecahydrate freeze crystallization system according to claim 7, characterized in that, The refrigeration module (50) further includes a refrigeration external circulation pump (54), which is used to enable the external circulation of the refrigerant liquid between the refrigeration water tank (51) and the second refrigeration crystallization module (30).

9. The sodium phosphate dodecahydrate freeze crystallization system according to claim 7, characterized in that, The refrigeration module (50) further includes a refrigerant liquid drain pump (55) and a refrigerant liquid collection tank (56) that are connected to each other. The refrigerant liquid drain pump (55) is connected to the refrigeration water tank (51), and the refrigerant liquid collection tank (56) is connected to the second refrigeration crystallization module (30).

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