Sodium sulfate decahydrate freezing crystallization system

Abstract

The utility model relates to the technical field of freezing crystallization, and discloses a sodium sulfate decahydrate freezing crystallization system which comprises a pre-cooling unit, a first freezing crystallization unit, a second freezing crystallization unit, a solid-liquid separation unit and a freezing unit which are connected in sequence, wherein the pre-cooling unit is used for pre-cooling a stock solution, the first freezing crystallization unit is used for performing primary freezing crystallization on the pre-cooled stock solution, and the second freezing crystallization unit is used for performing secondary freezing crystallization on a raw material discharged by the first freezing crystallization unit; the freezing unit is used for providing freezing liquid for the first freezing crystallization unit and the second freezing crystallization unit, and the solid-liquid separation unit is used for separating a crystal mush mixture discharged by the second freezing crystallization unit so as to prepare crystalline sodium sulfate decahydrate. According to the utility model, the requirement on the feeding concentration is lower, the material fluctuation resistance is high, the control difficulty is small, the salt outlet purity is high, and the crystallization productivity of sodium sulfate decahydrate is increased; the working efficiency of the freezing crystallization system is improved, and energy conservation and emission reduction are greatly realized.

Description

Technical Field

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

[0002] Sodium sulfate readily absorbs water when exposed to air, forming sodium sulfate decahydrate, also known as Glauber's salt. It is alkaline and is primarily used in the manufacture of water glass, glass, porcelain glaze, paper pulp, refrigeration mixtures, detergents, desiccants, dye thinners, analytical chemical reagents, pharmaceuticals, and feed.

[0003] With the recent development of the new energy industry, sodium sulfate continuous freeze crystallizers have been widely used in lithium hydroxide production, one-step lithium carbonate production impurity removal, and lithium carbonate battery recycling. However, during freeze crystallization, the narrow metastable zone of sodium sulfate easily crystallizes rapidly on the heat exchanger wall, forming crystal scars, which dramatically increases heat transfer resistance and reduces production capacity.

[0004] Therefore, how to provide a sodium sulfate decahydrate freeze crystallization system to increase the crystallization capacity of sodium sulfate decahydrate has become a technical problem that needs to be solved urgently. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a sodium sulfate decahydrate freezing crystallization system to increase the crystallization capacity of sodium sulfate decahydrate.

[0006] To this end, according to a first aspect, an embodiment of the present utility model discloses a sodium sulfate decahydrate freezing and crystallization system, comprising: a pre-cooling unit, a first freezing and crystallization unit, a second freezing and crystallization unit, a solid-liquid separation unit, and a freezing unit connected in sequence;

[0007] Among them, the pre-cooling unit is used to pre-cool the raw liquid, the first freezing and crystallization unit is used to perform a primary freezing and crystallization on the pre-cooled raw liquid, the second freezing and crystallization unit is used to perform a secondary freezing and crystallization on the raw material discharged from the first freezing and crystallization unit, the freezing unit is used to provide freezing liquid to the first freezing and crystallization unit and the second freezing and crystallization unit, and the solid-liquid separation unit is used to separate the slurry mixture discharged from the second freezing and crystallization unit to prepare crystalline sodium sulfate decahydrate.

[0008] The present invention is further configured such that the pre-cooling unit includes a pre-frozen liquid tank, a feed pump and a frozen mother liquid cooler connected in sequence, the pre-frozen liquid tank is used to temporarily store the raw liquid to be processed, the frozen mother liquid cooler is connected to the first frozen crystallization unit, and the frozen mother liquid cooler is used to pre-cool the raw liquid discharged by the feed pump.

[0009] The present invention is further configured such that a filter is installed between the feed pump and the refrigerated mother liquid cooler, and the filter is used to filter the raw liquid.

[0010] The present invention is further configured such that the first freezing crystallization unit includes a first external freezing cooler, a first circulation pump and a first freezing crystallizer that are cyclically connected in sequence, the first external freezing cooler is used to receive the freezing liquid provided by the freezing unit, and the first freezing crystallizer is used to perform a freezing crystallization on the pre-cooled original liquid.

[0011] The present invention is further configured such that the first refrigerated external cooler is connected to a first auxiliary circulation pump for ensuring a heat exchange effect of the first refrigerated external cooler.

[0012] The present invention is further configured such that the second freezing crystallization unit includes a second external freezing cooler, a second circulation pump and a second freezing crystallizer that are circulated in sequence, the second external freezing cooler is used to receive the freezing liquid provided by the freezing unit, and the second freezing crystallizer is used to perform secondary freezing crystallization on the raw materials discharged from the first freezing crystallization unit.

[0013] The present invention is further configured such that the second refrigerated external cooler is connected to a second auxiliary circulation pump for ensuring a heat exchange effect of the second refrigerated external cooler.

[0014] The present invention is further configured such that the solid-liquid separation includes a thickener, a centrifuge and a frozen mother liquor tank connected in sequence, the thickener is used to perform primary separation on the slurry mixture discharged from the second freezing crystallization unit, the centrifuge performs secondary separation on the slurry mixture, and discharges the frozen mother liquor into the frozen mother liquor tank.

[0015] The present invention is further configured such that the freezing unit comprises a freezing water tank, a freezing internal circulation pump and a freezing unit which are circulated in sequence, and the freezing water tank is connected to the first freezing crystallization unit and the second freezing crystallization unit respectively.

[0016] The present invention is further configured such that the freezing unit further comprises a freezing external circulation pump, and the freezing external circulation pump is used to allow the freezing liquid to circulate externally between the freezing water tank and the first freezing crystallization unit.

[0017] The utility model has the following beneficial effects: a pre-cooled stock solution is subjected to a primary freeze crystallization by the first freeze crystallization unit, and a raw material discharged from the first freeze crystallization unit is subjected to a secondary freeze crystallization by the second freeze crystallization unit, thereby providing a sodium sulfate decahydrate freeze crystallization system, which has low requirements on feed concentration, strong resistance to material fluctuation, low control difficulty, high salt purity, and increased crystallization capacity of sodium sulfate decahydrate; improves the working efficiency of the freeze crystallization system, and greatly saves energy and reduces emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of the structure of a sodium sulfate decahydrate freeze crystallization system disclosed in this embodiment;

[0020] Figure 2 This is a schematic structural diagram of a precooling unit in a sodium sulfate decahydrate freeze crystallization system disclosed in this embodiment;

[0021] Figure 3 This is a schematic structural diagram of a first freezing and crystallizing unit in a freezing and crystallizing system of sodium sulfate decahydrate disclosed in this embodiment;

[0022] Figure 4 This is a schematic structural diagram of a second freezing and crystallizing unit in a sodium sulfate decahydrate freezing and crystallizing system disclosed in this embodiment;

[0023] Figure 5 This is a schematic structural diagram of a solid-liquid separation unit in a sodium sulfate decahydrate freeze crystallization system disclosed in this embodiment;

[0024] Figure 6 This is a schematic structural diagram of a freezing unit in a sodium sulfate decahydrate freezing crystallization system disclosed in this embodiment;

[0025] Figure 7 This is a schematic flow chart of a sodium sulfate decahydrate freeze crystallization system disclosed in this embodiment.

[0026] Figure numerals: 10, pre-cooling unit; 11, pre-freezing liquid tank; 12, feed pump; 13, frozen mother liquor cooler; 14, filter; 20, first freezing crystallization unit; 21, first freezing external cooler; 22, first circulation pump; 23, first freezing crystallizer; 24, first auxiliary circulation pump; 25, transfer pump; 30, second freezing crystallization unit; 31, second freezing external cooler; 32, second circulation pump; 33, second freezing crystallizer; 34, second auxiliary circulation pump; 35, discharge pump; 40, solid-liquid separation unit; 41, thickener; 42, centrifuge; 43, frozen mother liquor tank; 44, frozen mother liquor pump; 50, freezing unit; 51, freezing water tank; 52, freezing internal circulation pump; 53, refrigeration unit; 54, freezing external circulation pump. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is 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 invention and are not intended to limit the present invention.

[0028] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal connections between two components; they may refer to wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0029] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

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

[0031] The embodiment of the utility model discloses a sodium sulfate decahydrate freezing crystallization system, such as Figure 1-7 As shown, it includes: a pre-cooling unit 10, a first freezing and crystallization unit 20, a second freezing and crystallization unit 30, a solid-liquid separation unit 40 and a freezing unit 50 connected in sequence;

[0032] Among them, the pre-cooling unit 10 is used to pre-cool the raw liquid, the first freezing and crystallization unit 20 is used to perform a first freezing and crystallization on the pre-cooled raw liquid, the second freezing and crystallization unit 30 is used to perform a second freezing and crystallization on the raw material discharged from the first freezing and crystallization unit 20, the freezing unit 50 is used to provide freezing liquid to the first freezing and crystallization unit 20 and the second freezing and crystallization unit 30, and the solid-liquid separation unit 40 is used to separate the slurry mixture discharged from the second freezing and crystallization unit 30 to prepare crystalline sodium sulfate decahydrate.

[0033] It should be noted that the pre-cooled raw liquid is subjected to a primary freeze crystallization by the first freezing crystallization unit 20, and the raw material discharged from the first freezing crystallization unit 20 is subjected to a secondary freeze crystallization by the second freezing crystallization unit 30, thereby providing a sodium sulfate decahydrate freeze crystallization system, which has low requirements on feed concentration, strong resistance to material fluctuations, low control difficulty, high salt purity, and increased crystallization capacity of sodium sulfate decahydrate; improves the working efficiency of the freezing crystallization system, and greatly saves energy and reduces emissions.

[0034] like Figure 1 and Figure 2 As shown, the pre-cooling unit 10 includes a pre-frozen liquid tank 11, a feed pump 12, and a frozen mother liquid cooler 13, which are connected in sequence. The pre-frozen liquid tank 11 is used to temporarily store the raw liquid to be processed. The frozen mother liquid cooler 13 is connected to the first freezing crystallizer 20 and is used to pre-cool the raw liquid discharged by the feed pump 12. The frozen mother liquid cooler 13 is connected to the first freezing crystallizer 23.

[0035] like Figure 1 and Figure 2 As shown, a filter 14 is installed between the feed pump 12 and the frozen mother liquid cooler 13. The filter 14 is used to filter the raw liquid. In the specific implementation process, the filter 14 is a security filter 14. The setting of the filter 14 allows the raw liquid to be better frozen and crystallized, thereby improving the purity of sodium sulfate decahydrate.

[0036] like Figure 1-3 As shown, the first freezing and crystallization unit 20 includes a first external refrigeration cooler 21, a first circulation pump 22, and a first freezing crystallizer 23, which are connected in a circular manner. The first external refrigeration cooler 21 is used to receive the refrigerant provided by the freezing unit 50, and the first freezing crystallizer 23 is used to perform a primary freezing and crystallization on the pre-cooled raw liquid. In the specific implementation process, the number of first external refrigeration coolers 21 and first circulation pumps 22 is set to two, forming one main and one backup. The crystallization temperature of sodium sulfate decahydrate in the first freezing crystallizer 23 is 20°C.

[0037] It should be noted that the first refrigeration external cooler 21 is connected to the refrigeration water tank 51 and the refrigeration external circulation pump 54 respectively.

[0038] like Figure 1-3 As shown, the first external refrigeration cooler 21 is connected to a first auxiliary circulation pump 24 for ensuring the heat exchange effect of the first external refrigeration cooler 21 .

[0039] like Figure 1-4As shown, the second freezing and crystallization unit 30 includes a second external freezing cooler 31, a second circulation pump 32, and a second freezing crystallizer 33, which are connected in a circular manner. The second external freezing cooler 31 is used to receive the freezing liquid provided by the freezing unit 50, and the second freezing crystallizer 33 is used to perform secondary freezing and crystallization of the raw materials discharged from the first freezing and crystallization unit 20. In the specific implementation process, the number of second external freezing coolers 31 and second circulation pumps 32 is set to two, forming one main and one backup. The crystallization temperature of sodium sulfate decahydrate in the second freezing crystallizer 33 is 5°C.

[0040] It should be noted that the first freezing crystallizer 23 is connected to the second freezing crystallizer 33 via a transfer pump 25, and the second external refrigeration cooler 31 is connected to the chilled water tank 51 and the external refrigeration circulation pump 54. The second freezing crystallizer 33 is connected to the thickener 41 via a discharge pump 35.

[0041] like Figure 1-4 As shown, the second external refrigeration cooler 31 is connected to a second auxiliary circulation pump 34 for ensuring the heat exchange effect of the second external refrigeration cooler 31 .

[0042] like Figure 1-5 As shown, the solid-liquid separation process includes a thickener 41, a centrifuge 42, and a frozen mother liquor tank 43, which are connected in sequence. The thickener 41 is used to perform primary separation on the slurry mixture discharged from the second freezing and crystallization unit 30. The centrifuge 42 performs secondary separation on the slurry mixture and discharges the frozen mother liquor into the frozen mother liquor tank 43. It should be noted that the stirring and separation of the thickener 41 and the centrifuge 42 can produce crystallized sodium sulfate decahydrate. The frozen mother liquor tank 43 delivers the frozen mother liquor to the frozen mother liquor cooler 13 via the frozen mother liquor pump 44.

[0043] like Figure 1-6 As shown, the freezing unit 50 includes a chilled water tank 51, a chilled internal circulation pump 52, and a refrigeration unit 53, which are connected in a sequential manner. The chilled water tank 51 is connected to the first freezing and crystallization unit 20 and the second freezing and crystallization unit 30. It should be noted that the refrigerant produced by the refrigeration unit 53 is stored in the chilled water tank 51; the chilled water tank 51 can provide cooling capacity to the first and second refrigeration external coolers 21 and 31, ensuring smooth crystallization in the first and second refrigeration crystallizers 23 and 33.

[0044] like Figure 1-6 As shown, the freezing unit 50 further includes a freezing external circulation pump 54 , which is used to allow the freezing liquid to circulate externally between the freezing water tank 51 and the first freezing crystallization unit 20 .

[0045] During the specific implementation process, the refrigerated mother liquid is heat exchanged with the feed according to the material characteristics before being discharged, fully utilizing the system's cooling value and reducing system operating energy consumption. To avoid pipe blockage, the circulation pumps of this utility model all use high-flow, low-head axial flow pumps with a designed flow rate in the pipe of 2-3m / s.

[0046] Working principle: The pre-cooled raw liquid is subjected to a primary freeze crystallization by the first freeze crystallization unit 20, and the raw material discharged from the first freeze crystallization unit 20 is subjected to a secondary freeze crystallization by the second freeze crystallization unit 30, thereby providing a sodium sulfate decahydrate freeze crystallization system with low requirements on feed concentration, strong resistance to material fluctuation, low control difficulty, high salt purity, and increased crystallization capacity of sodium sulfate decahydrate; the working efficiency of the freeze crystallization system is improved, and energy conservation and emission reduction are greatly reduced.

[0047] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A sodium sulfate decahydrate freeze crystallization system, characterized in that: include: A pre-cooling unit (10), a first freezing and crystallizing unit (20), a second freezing and crystallizing unit (30), a solid-liquid separation unit (40), and a freezing unit (50) connected in sequence; The precooling unit (10) is used to precool the raw liquid, the first freezing and crystallization unit (20) is used to perform a primary freezing and crystallization on the precooled raw liquid, the second freezing and crystallization unit (30) is used to perform a secondary freezing and crystallization on the raw material discharged from the first freezing and crystallization unit (20), the freezing unit (50) is used to provide freezing liquid to the first freezing and crystallization unit (20) and the second freezing and crystallization unit (30), and the solid-liquid separation unit (40) is used to separate the slurry mixture discharged from the second freezing and crystallization unit (30) to prepare crystalline sodium sulfate decahydrate.

2. The sodium sulfate decahydrate freeze crystallization system according to claim 1, wherein The pre-cooling unit (10) includes a pre-frozen liquid tank (11), a feed pump (12) and a frozen mother liquid cooler (13) which are connected in sequence. The pre-frozen liquid tank (11) is used to temporarily store the raw liquid to be processed. The frozen mother liquid cooler (13) is connected to the first frozen crystallization unit (20). The frozen mother liquid cooler (13) is used to pre-cool the raw liquid discharged by the feed pump (12).

3. The sodium sulfate decahydrate freeze crystallization system according to claim 2, wherein A filter (14) is installed between the feed pump (12) and the refrigerated mother liquid cooler (13), and the filter (14) is used to filter the raw liquid.

4. The sodium sulfate decahydrate freeze crystallization system according to any one of claims 1 to 3, characterized in that The first freezing crystallization unit (20) includes a first external freezing cooler (21), a first circulation pump (22) and a first freezing crystallizer (23) which are cyclically connected in sequence. The first external freezing cooler (21) is used to receive the freezing liquid provided by the freezing unit (50), and the first freezing crystallizer (23) is used to perform a freezing crystallization on the pre-cooled raw liquid.

5. The sodium sulfate decahydrate freeze crystallization system according to claim 4, wherein The first refrigerated external cooler (21) is connected to a first auxiliary circulation pump (24) for ensuring the heat exchange effect of the first refrigerated external cooler (21).

6. The sodium sulfate decahydrate freeze crystallization system according to any one of claims 1 to 3, characterized in that: The second freezing crystallization unit (30) includes a second freezing external cooler (31), a second circulation pump (32) and a second freezing crystallizer (33) which are cyclically connected in sequence. The second freezing external cooler (31) is used to receive the freezing liquid provided by the freezing unit (50), and the second freezing crystallizer (33) is used to perform secondary freezing crystallization on the raw materials discharged from the first freezing crystallization unit (20).

7. The sodium sulfate decahydrate freeze crystallization system according to claim 6, wherein The second refrigerated external cooler (31) is connected to a second auxiliary circulation pump (34) for ensuring the heat exchange effect of the second refrigerated external cooler (31).

8. The sodium sulfate decahydrate freeze crystallization system according to any one of claims 1 to 3, characterized in that: The solid-liquid separation includes a thickener (41), a centrifuge (42) and a frozen mother liquor tank (43) connected in sequence, the thickener (41) is used to perform primary separation on the slurry mixture discharged from the second freezing crystallization unit (30), the centrifuge (42) performs secondary separation on the slurry mixture, and discharges the frozen mother liquor into the frozen mother liquor tank (43).

9. The sodium sulfate decahydrate freeze crystallization system according to any one of claims 1 to 3, characterized in that: The freezing unit (50) comprises a freezing water tank (51), a freezing internal circulation pump (52) and a freezing unit (53) which are circulated in sequence, and the freezing water tank (51) is connected to the first freezing crystallization unit (20) and the second freezing crystallization unit (30) respectively.

10. The sodium sulfate decahydrate freeze crystallization system according to claim 9, characterized in that: The freezing unit (50) further comprises a freezing external circulation pump (54), and the freezing external circulation pump (54) is used to allow the freezing liquid to circulate externally between the freezing water tank (51) and the first freezing crystallization unit (20).

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