Sodium sulfate freezing continuous crystallization device

Abstract

The utility model relates to the technical field of sewage treatment, and discloses a sodium sulfate freezing continuous crystallization device which comprises a feeding pump, a refrigerant heat exchanger, a crystallizer, a first discharging pump, a second discharging pump, a first centrifugal machine, a second centrifugal machine, a mother liquor tank and a circulating pump. The discharge end of the crystallizer is connected to a centrifugal machine II through a discharge pump II; a sodium sulfate concentration online monitor is mounted in the mother liquor tank; a freezing tank is arranged between the feeding pump and the refrigerant heat exchanger, a first heat exchange pipe is installed on the upper portion in the freezing tank, and the bottom of the freezing tank is connected to a second centrifugal machine through a second discharging pump. Through the arrangement of the freezing tank and the first heat exchange pipe, preliminary cooling and crystallization of a salt solution can be achieved, and the blocking condition is effectively reduced; one part of the mother liquor enters the heat exchange pipe II to prerefrigerate the salt solution entering the freezing tank, so that the refrigeration efficiency of the salt solution in the freezing tank is improved, and the cooling capacity of the mother liquor is fully utilized.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically a sodium sulfate freezing continuous crystallization device. Background Technology

[0002] Currently, the main wastewater treatment processes are largely standardized, achieving zero discharge primarily through a combination of processes including pretreatment, membrane concentration, nanofiltration desalination, and cryogenic crystallization. Among these, cryogenic crystallization technology uses freezing to lower the wastewater to a specific temperature. Because sodium sulfate's solubility is highly sensitive to temperature, it crystallizes and precipitates out of the wastewater when the temperature reaches a suitable level. In practice, the mother liquor after sodium sulfate separation is partially recycled and mixed with the unfrozen nanofiltration concentrate; the remainder is discharged. However, due to the high wastewater temperature and the relatively low cryogenic crystallization temperature, the large temperature difference between the heat exchanger inlet and outlet leads to significant crystal precipitation, potentially causing blockage. Furthermore, the low temperature of the mother liquor results in wasted cooling capacity when directly discharged, necessitating improvements. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the above-mentioned technical defects and provide a sodium sulfate freezing continuous crystallization device.

[0004] To solve the above problems, the technical solution of this utility model is as follows: a sodium sulfate freezing continuous crystallization device, including a feed pump, a refrigerant heat exchanger, a crystallizer, a discharge pump one, a discharge pump two, a centrifuge one, a centrifuge two, a mother liquor tank and a circulation pump. The refrigerant heat exchanger is located between the feed pump and the crystallizer. The discharge end of the crystallizer is connected to the centrifuge one through the discharge pump one. An online sodium sulfate concentration monitoring instrument is installed inside the mother liquor tank.

[0005] It also includes a refrigeration tank located between the feed pump and the refrigerant heat exchanger, wherein a heat exchange tube is installed in the upper part of the refrigeration tank, and the bottom of the refrigeration tank is connected to a centrifuge via a discharge pump.

[0006] The drain ends of the crystallizer, centrifuge one, and centrifuge two are all connected to the mother liquor tank, which is connected to the inlet of the refrigerant heat exchanger via a circulating pump.

[0007] Furthermore, the bottom of the freezing tank has a conical design.

[0008] Furthermore, both the refrigerant heat exchanger and the heat exchange tube are connected to the refrigerant circulation system.

[0009] Furthermore, a pretreatment box is provided between the feed pump and the freezing tank, and a second heat exchange tube is installed in the pretreatment box.

[0010] Furthermore, the input end of the second heat exchange tube is connected to the output end of the circulating pump, and solenoid valves are provided on the connecting pipes of the circulating pump, the refrigerant heat exchanger, and the second heat exchange tube.

[0011] The advantages of this invention compared with existing technologies are as follows: This invention can achieve preliminary cooling and crystallization of the salt solution through the setting of the freezing tank and heat exchange tube one, effectively reducing the possibility of blockage; a portion of the mother liquor enters the heat exchange tube two to pre-cool the salt solution entering the freezing tank, thereby improving the cooling efficiency of the salt solution in the freezing tank and making full use of the cooling capacity of the mother liquor. Attached Figure Description

[0012] Figure 1 This is a structural diagram of the present invention.

[0013] As shown in the figure: 1. Feed pump; 2. Refrigerant heat exchanger; 3. Crystallizer; 4. Discharge pump one; 5. Discharge pump two; 6. Centrifuge one; 7. Centrifuge two; 8. Mother liquor tank; 9. Circulation pump; 10. Freezing tank; 11. Heat exchange tube one; 12. Pretreatment box; 13. Heat exchange tube two. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0015] like Figure 1 As shown, a sodium sulfate freezing continuous crystallization device includes a feed pump 1, a refrigerant heat exchanger 2, a crystallizer 3, a discharge pump 1 4, a discharge pump 2 5, a centrifuge 1 6, a centrifuge 2 7, a mother liquor tank 8, and a circulation pump 9. The refrigerant heat exchanger 2 is located between the feed pump 1 and the crystallizer 3. The discharge end of the crystallizer 3 is connected to the centrifuge 6 through the discharge pump 1 4. An online sodium sulfate concentration monitoring instrument is installed inside the mother liquor tank 8.

[0016] It also includes a freezing tank 10 located between the feed pump 1 and the refrigerant heat exchanger 2. A heat exchange tube 11 is installed in the upper part of the freezing tank 10. The bottom of the freezing tank 10 is conical and its bottom is connected to the centrifuge 7 via a discharge pump 5. Both the refrigerant heat exchanger 2 and the heat exchange tube 11 are connected to the refrigerant circulation system.

[0017] Feed pump 1 adds sodium sulfate salt solution to freezer tank 10. Heat exchange tube 11 can achieve preliminary cooling of salt solution. The crystallized sodium sulfate crystals settle and are transported to centrifuge 7 by discharge pump 25 for solid-liquid separation. The separated liquid is transported to mother liquor tank 8.

[0018] The drain ends of crystallizer 3, centrifuge 6 and centrifuge 7 are all connected to mother liquor tank 8, which is connected to the inlet of refrigerant heat exchanger 2 via circulating pump 9.

[0019] A pretreatment box 12 is also provided between the feed pump 1 and the refrigeration tank 10. A second heat exchange tube 13 is installed in the pretreatment box 12. The input end of the second heat exchange tube 13 is connected to the output end of the circulating pump 9. Solenoid valves are provided on the connecting pipes of the circulating pump 9, the refrigerant heat exchanger 2, and the second heat exchange tube 13.

[0020] When the sodium sulfate concentration inside the mother liquor tank 8 is lower than the set value, the solenoid valve on the connecting pipe between the circulation pump 9 and the heat exchange tube 13 is opened. Part of the mother liquor enters the refrigerant heat exchanger 2 to participate in circulation, and the other part enters the heat exchange tube 13 to pre-cool the salt solution entering the freezer tank 10, thereby improving the cooling efficiency of the salt solution in the freezer tank 10. After heat exchange, the mother liquor in the heat exchange tube 13 is discharged into the waste liquid tank for waste liquid treatment.

[0021] In practical use, the setup of the freezer tank 10 and the heat exchange tube 11 enables the initial cooling and crystallization of the salt solution, effectively reducing the amount of crystal precipitation in the refrigerant heat exchanger 2, and thus effectively reducing the blockage. When the sodium sulfate concentration inside the mother liquor tank 8 is lower than the set value, a portion of the mother liquor enters the heat exchange tube 13 to pre-cool the salt solution entering the freezer tank 10, thereby improving the cooling efficiency of the salt solution in the freezer tank 10.

[0022] The parts not disclosed in this utility model are all prior art, and their specific structures and working principles will not be described in detail.

[0023] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0024] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

[0025] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A sodium sulfate freezing continuous crystallization apparatus, comprising a feed pump (1), a refrigerant heat exchanger (2), a crystallizer (3), a discharge pump one (4), a discharge pump two (5), a centrifuge one (6), a centrifuge two (7), a mother liquor tank (8), and a circulation pump (9), wherein the refrigerant heat exchanger (2) is located between the feed pump (1) and the crystallizer (3), and the discharge end of the crystallizer (3) is connected to the centrifuge one (6) via the discharge pump one (4), characterized in that: It also includes a freezing tank (10) located between the feed pump (1) and the refrigerant heat exchanger (2), wherein a heat exchange tube (11) is installed in the upper part of the freezing tank (10), and the bottom of the freezing tank (10) is connected to a centrifuge (6) via a discharge pump (4); The drain ends of the crystallizer (3), centrifuge one (6) and centrifuge two (7) are all connected to the mother liquor tank (8), and the mother liquor tank (8) is connected to the inlet of the refrigerant heat exchanger (2) through the circulation pump (9).

2. A sodium sulfate freezing continuous crystallization apparatus as defined in claim 1, wherein: The bottom of the freezer (10) is tapered.

3. A sodium sulfate freezing continuous crystallization apparatus as defined in claim 1, wherein: The refrigerant heat exchanger (2) and heat exchange tube 1 (11) are both connected to the refrigerant circulation system.

4. A sodium sulfate freezing continuous crystallization apparatus as defined in claim 1, wherein: A pretreatment box (12) is also provided between the feed pump (1) and the freezing tank (10), and a heat exchange tube (13) is installed in the pretreatment box (12).

5. A sodium sulfate freezing continuous crystallization apparatus as defined in claim 4, wherein: The input end of the second heat exchange tube (13) is connected to the output end of the circulating pump (9), and the connecting pipes of the circulating pump (9) to the refrigerant heat exchanger (2) and the second heat exchange tube (13) are all equipped with solenoid valves.

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