Device for eliminating fine crystals in cooling crystallization process of sodium sulfate

Abstract

The utility model discloses a device for eliminating fine crystals in a sodium sulfate cooling crystallization process, which is characterized in that a #-shaped partition plate is arranged below a top cover of a crystallizer, a cross-shaped flow channel formed in an inner baffle of the partition plate comprises radial branches, each radial branch is provided with a fine crystal liquid interface, a hot material liquid backflow interface and a circulating liquid interface, each fine crystal liquid interface is close to the center of the top cover, and each hot material liquid interface is close to the center of the top cover. A hot material liquid backflow connector is arranged on the outer side of the crystallizer and is close to the inner wall of the crystallizer; each fine crystal liquid interface is connected with an inlet pipeline of the fine crystal circulating pump, an outlet of the fine crystal circulating pump is connected with a tube pass inlet of the heat exchanger, and a tube pass outlet of the heat exchanger is connected with the hot material liquid backflow interface; each circulating liquid interface is connected with a suction port pipeline of a feed liquid circulating pump, an outlet of the feed liquid circulating pump is connected with a tube pass inlet of an external cooler, a tube pass outlet of the external cooler and a sodium sulfate solution feeding pipe are jointly connected with a feeding port of a crystallizer, and a crystal mush outlet is formed in the lower part of the side wall of the crystallizer. The device can improve the particle size of product cooling crystallization and prolong the cleaning period of the external cooler.

Description

Technical Field

[0001] The utility model relates to a sodium sulfate crystallization device, in particular to a device for eliminating fine crystals in the sodium sulfate cooling crystallization process, belonging to the technical field of cooling crystallization devices. Background Art

[0002] Sodium sulfate is a salt formed by the combination of sulfate and sodium ions. It is soluble in water, and its solutions are mostly neutral. It is soluble in glycerin but insoluble in ethanol. It is an inorganic compound. High-purity, fine-grained anhydrous sodium sulfate is called glauber's salt. Glauber's salt is a white, odorless, bitter crystal or powder that is hygroscopic. It appears as colorless, transparent, large crystals or small granular crystals. Sodium sulfate readily absorbs water when exposed to air, forming sodium sulfate decahydrate, also known as sodium sulfate decahydrate, which is slightly alkaline. Glauber's salt is primarily used in the manufacture of waterglass, glass, porcelain glaze, paper pulp, refrigerant mixtures, detergents, desiccants, dye thinners, analytical chemical reagents, pharmaceuticals, and feed.

[0003] The current sodium sulfate cooling crystallization process generally adopts a circulating cooling method, forcing the high-temperature circulating sodium sulfate saturated liquid to an external cooler to exchange heat with the freezing medium, and the freezing medium is cooled by a refrigeration unit, so as to achieve the purpose of cooling and crystallizing the sodium sulfate salt. The precipitated sodium sulfate solid salt is extracted by a slurry pump to a thickener and then discharged by centrifuge.

[0004] Chinese patent application publication number CN 110870984A discloses a continuous crystallizer and its continuous crystallization process. The continuous crystallizer includes a cooling crystallization system and a circulating constant temperature condensation system. The crystallizer is connected to the constant temperature condensation system through the liquid inlet and liquid outlet. The internal guide tube of the crystallizer has an interlayer. The circulating water temperature of the interlayer of the cylinder and the inner interlayer of the guide tube is the same, which greatly saves cooling time. The crystallizer is stirred by downward pressure. The crystallizer is equipped with a baffle. The area between the baffle and the wall of the crystallization tank is a clear liquid area. The small tank next to the crystallization tank is a crystallization tank to eliminate fine crystals in the clear liquid area. This technical solution has the following problems: the fine crystallization tank is a small kettle with a jacket. For the crystallization of sodium sulfate with a small flow rate, the jacketed heat exchange takes up a large area and has low heat exchange efficiency. The straight-through flow channel with bottom inlet and top outlet is prone to salt pushing crystals and scorching the inner wall. Utility Model Content

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and utility model title of this application, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0007] The purpose of the utility model is to overcome the technical difficulty of eliminating fine particles in the cooling crystallization of sodium sulfate, provide a device for eliminating fine crystals in the cooling crystallization process of sodium sulfate, achieve the growth of larger particles in the cooling crystallization, improve the particle size of the product cooling crystallization, lengthen the cleaning cycle of the external cooler, and provide feasible optimization for the cooling crystallization process of sodium sulfate.

[0008] In order to solve the above technical problems, the utility model provides a device for eliminating fine crystals in the cooling crystallization process of sodium sulfate, comprising a crystallizer, wherein symmetrically distributed well-shaped partitions are provided below the top cover of the crystallizer, and the inner parts of the well-shaped partitions form a cross-shaped flow channel below the top cover, and the cross-shaped flow channel includes four radial branches extending along the radius.

[0009] Each radial branch is provided with a fine crystal liquid interface, a hot liquid reflux interface and a circulating liquid interface, each fine crystal liquid interface is close to the center of the top cover, each hot liquid reflux interface is located radially outside each fine crystal liquid interface, and each circulating liquid interface is close to the inner wall of the crystallizer;

[0010] Each fine crystal liquid interface is connected to the inlet pipe of the fine crystal circulation pump, the outlet of the fine crystal circulation pump is connected to the tube side inlet of the heat exchanger through the fine crystal circulation pipe, and the tube side outlet of the heat exchanger is connected to the corresponding hot material liquid reflux interface;

[0011] Each circulating liquid interface is connected to the suction pipe of the liquid circulation pump, the outlet of the liquid circulation pump is connected to the tube side inlet of the external cooler through the liquid circulation pipe, the tube side outlet of the external cooler and the sodium sulfate solution feed pipe are jointly connected to the feed port of the crystallizer, and a slurry outlet is provided at the lower part of the side wall of the crystallizer.

[0012] As an improvement of the present invention, the lower edge of the well-shaped partition is 2 to 6 cm away from the lower end surface of the top cover, and the closer to the center of the top cover, the deeper the depth of the well-shaped partition; the closer to the periphery of the top cover, the shallower the depth of the well-shaped partition.

[0013] As a further improvement of the present invention, the lower port of the fine crystal liquid interface is within 2 cm from the lower end surface of the top cover or is flush with the lower end surface of the top cover, the lower port of the hot material liquid reflux interface is lower than the lower edge of the well-shaped partition, and the lower port of the circulating liquid interface is lower than the lower port of the hot material liquid reflux interface.

[0014] As a further improvement of the present invention, the tube-side outlet pipes of each heat exchanger are respectively connected to the fine crystal flushing pipes, and the outlets of each fine crystal flushing pipe are respectively connected to the tube-side inlet of the corresponding external cooler.

[0015] As a further improvement of the present invention, the external cooler, heat exchanger, fine crystal circulation pump and liquid circulation pump are provided in four groups, corresponding to the four branches of the cross-shaped flow channel respectively.

[0016] Compared with the existing technology, the utility model has achieved the following beneficial effects: 1. It realizes more stable industrial production of sodium sulfate low-temperature crystallization, improves the product quality of sodium sulfate cooling crystallization, increases the average particle size of sodium sulfate products, and sells them at a price 70 to 80 yuan per ton higher than that of ordinary sodium sulfate, thereby increasing the profit margin of the product and expanding the application areas of the product;

[0017] 2. The use of high temperature to eliminate the crystal water in the sodium sulfate reduces the probability of small crystals clogging the external cooler, extends the average operating cycle of the external cooler, and reduces the labor cost of operating the device;

[0018] 3. The high-temperature material after the heat exchanger is used to flush the blocked external cooler pipe, which reduces the valve and pipeline settings, reduces the tediousness of personnel operations, and effectively improves the stability of the device operation. There is no need to stop production and discharge materials, nor is there any need to introduce other media for dredging;

[0019] 4. The OSLO crystallizer is used for evaporation crystallization, which effectively improves the crystal size of sodium sulfate and increases the added value of the product. At the same time, the OSLO crystallizer circulating liquid interface adopts a cross four-opening type to prevent the blockage of the lower cylinder of the crystallizer to the greatest extent. The crystallizer discharge port is reasonably set to ensure the content of large-particle sodium sulfate in the discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. The drawings are only provided for reference and explanation, and are not intended to limit the present invention. Among them:

[0021] Figure 1 This is a flow chart of the device for eliminating fine crystals during the crystallization process of sodium sulfate by cooling according to the utility model;

[0022] Figure 2 This is a bottom view of the crystallizer top cover;

[0023] Figure 3 is a cross-sectional view of the crystallizer top cover;

[0024] In the figure: 1. Crystallizer; 1a. Draft tube; 1b. Fine crystal liquid interface; 1c. Hot liquid reflux interface; 1d. Circulating liquid interface; 1e. Slurry outlet; 1f. Drain outlet; 1g. Top cover; 1h. Well-shaped partition; 2. External cooler; 3. Heat exchanger;

[0025] B1. Fine crystal circulation pump; B2. Liquid circulation pump; B3. Slurry pump;

[0026] G1. Sodium sulfate solution feed pipe; G2. Fine crystal circulation pipe; G3. Liquid circulation pipe; G4. Steam pipe; G5. Heater condensate pipe; G6. Refrigerant water supply pipe; G7. Refrigerant return pipe; G8. Fine crystal flushing pipe; G9. Slurry discharge pipe. DETAILED DESCRIPTION

[0027] In the following description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific direction.

[0028] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the embodiments described are only a part of the present invention, not all of the embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0030] like Figures 1 to 3 As shown, the present invention comprises a device for eliminating fine crystals during the cooling crystallization process of sodium sulfate, comprising a crystallizer 1, an external cooler 2, and a heat exchanger 3. Symmetrically arranged crisscross-shaped baffles are provided below the top cover of the crystallizer 1. The lower edges of the crisscross-shaped baffles are 2 to 6 cm from the lower end surface of the top cover. The closer to the center of the top cover, the deeper the crisscross-shaped baffles sag; the closer to the periphery of the top cover, the shallower the crisscross-shaped baffles sag. The inner edges of the crisscross-shaped baffles form a cross-shaped flow channel below the top cover.

[0031] The cross-shaped flow channel forms four radial branches extending along the radius of the lower end surface of the top cover. Each radial branch is equipped with a fine crystal liquid interface 1b, a hot liquid return interface 1c, and a circulating liquid interface 1d. The four groups of fine crystal liquid interfaces 1b, hot liquid return interface 1c, and circulating liquid interface 1d are arranged symmetrically around the center. Each fine crystal liquid interface 1b is located near the center of the top cover, the hot liquid return interface 1c is located radially outward of each fine crystal liquid interface 1b, and each circulating liquid interface 1d is located near the inner wall of the crystallizer 1.

[0032] The lower port of the fine crystal liquid interface 1b is within 2 cm from the lower end surface of the top cover or flush with the lower end surface of the top cover, and the fine crystals floating on the top are sucked from a position close to the central area, and the fine crystals flow toward the center along the cross-shaped flow channel.

[0033] The lower port of the hot liquid return port 1c is lower than the lower edge of the well-shaped partition, allowing the heated liquid to reach below the fine crystal layer and then flow radially outward. The lower port of the circulating liquid port 1d is lower than the lower port of the hot liquid return port 1c, allowing the hot liquid to mix with the liquid in the vessel.

[0034] The inlet pipe of each fine crystal circulation pump B1 is connected to the fine crystal liquid interface 1b. The outlet of fine crystal circulation pump B1 is connected to the tube-side inlet of heat exchanger 3 through fine crystal circulation pipe G2. The tube-side outlet of heat exchanger 3 is connected to the corresponding hot liquid reflux interface 1c. The shell-side inlet of heat exchanger 3 is connected to steam pipe G4, and the shell-side outlet of heat exchanger 3 is connected to heater condensate pipe G5.

[0035] The suction pipe of the liquid circulation pump B2 is connected to the circulating liquid interface 1d. The outlet of the liquid circulation pump B2 is connected to the tube-side inlet of the external cooler 2 via the liquid circulation pipe G3. The shell-side inlet of the external cooler 2 is connected to the refrigerant water supply pipe G6, and the shell-side outlet of the external cooler 2 is connected to the refrigerant water return pipe G7. The tube-side outlet of the external cooler 2 is connected to the feed port of the flow guide pipe 1a of the crystallizer 1. The flow guide pipe 1a extends to the center of the crystallizer 1 and bends downward to the bottom of the crystallizer 1. The lower end of the flow guide pipe 1a is equipped with a bell mouth.

[0036] A slurry outlet 1e is provided at the lower part of the side wall of the crystallizer 1, and a sewage outlet 1f is provided at the lowest point of the bottom wall of the crystallizer 1, both of which are connected to the inlet of the slurry pump B3, and the outlet of the slurry pump B3 is connected to the slurry discharge pipe G9.

[0037] The tube-side outlet pipes of each heat exchanger 3 are respectively connected to the fine crystal flushing pipe G8 , and the outlets of each fine crystal flushing pipe G8 are respectively connected to the tube-side inlet of the external cooler 2 .

[0038] Saturated sodium sulfate liquid from sodium sulfate solution feed pipe G1 is mixed with cooled sodium sulfate slurry and enters crystallizer 1. It enters the center of the bottom through draft tube 1a inside crystallizer 1 and then circulates upward. Crystallization continues as it ascends, with large-particle sodium sulfate descending and small-particle sodium sulfate ascending. By the time the supersaturated liquid reaches the top, small-particle sodium sulfate particles have accumulated, gathering approximately 2-3 cm below the top cover. They are then pumped out through fine crystal liquid interface 1b by fine crystal circulation pump B1 and enter the tube side of heat exchanger 3 via fine crystal circulation pipe G2. Steam from steam pipe G4 enters the shell side of heat exchanger 3, indirectly heating the liquid. After heat exchange, the condensate is discharged and recycled through heater condensate pipe G5. The liquid flowing through the tube side is heated by the shell-side steam, melting the small-particle sodium sulfate particles entrained in the liquid. The small-particle sodium sulfate then returns to the top of crystallizer 1 through hot liquid reflux interface 1c.

[0039] The heated liquid is pumped from circulating liquid port 1d by liquid circulation pump B2 and fed through liquid circulation pipe G3 into the tube side of external cooler 2 for cooling. It then exchanges heat with the refrigerant water in the shell side. The low-temperature refrigerant water enters the shell side inlet of external cooler 2 through refrigerant supply pipe G6. After heat exchange, it exits through refrigerant return pipe G7. After cooling, the liquid reaches saturation and mixes with saturated sodium sulfate solution from sodium sulfate solution feed pipe G1. It then enters draft pipe 1a of crystallizer 1, flows along draft pipe 1a to the center of the bottom of crystallizer 1, and then flows upward, repeating the cycle. During this upward movement, large-particle sodium sulfate settles downward, resulting in a large-particle sodium sulfate slurry at the bottom. The slurry density reaches 1.35±0.01g / ml, with a particle size (≥1500μm) accounting for ≥80%. It is discharged from slurry outlet 1e on the lower sidewall by slurry pump B3 and sent through slurry discharge pipe G9 to the centrifugal section for separation of the large-particle sodium sulfate.

[0040] When there is a risk of blockage in the pipe side of the external cooler 2, high-temperature liquid is drawn out from the pipe side outlet of the heat exchanger 3 and injected into the pipe side inlet of the external cooler 2 through the fine crystal flushing pipe G8, and the high-temperature liquid is used to dissolve crystals and clear the inner wall of the pipeline; the possibility of salt accumulation on the wall of the external cooler 2 is reduced, and the cleaning cycle of the external cooler 2 is extended.

[0041] There are four groups of external cooler 2, heat exchanger 3, fine crystal circulation pump B1 and liquid circulation pump B2, which correspond to the four branches of the cross-shaped flow channel respectively. Three groups are in normal operation, and one group is on standby for flushing. Then the group that has been flushed is put into operation, and the group that was originally in operation stops and enters standby. This cycle can ensure long-term stable operation of the device.

[0042] The crystallizer 1 adopts an OSLO type crystallizer with upper separation + lower crystallization. The external cooler 2 and the heat exchanger 3 both adopt double-pass shell and tube heat exchangers. The double-pass shell and tube heat exchanger allows the materials that need to be cooled / heated to enter and exit from the same side. Baffles are set on the shell side to increase the path required for the heat exchange medium to take, improve the heat exchange efficiency, and reduce the floor space.

[0043] The fine crystal circulation pump B1 adopts the form of a gear pump, which increases the stability of the circulation flow and reduces the floor space.

[0044] The liquid circulation pump B2 and the refrigerant circulation pump adopt the form of vertical axial flow pumps. The impeller of the vertical axial flow pump is arranged radially with the material flow direction, which effectively increases the material flow rate. It can be directly installed on equipment and pipelines, effectively reducing installation costs and reducing floor space.

[0045] The above description is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation methods without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. Technical features not described in the present invention can be achieved by or using existing technologies, and will not be described here.

Claims

1. A device for eliminating fine crystals in the crystallization process of sodium sulfate by cooling, comprising a crystallizer, characterized in that: A symmetrically distributed well-shaped partition is provided below the top cover of the crystallizer. The inner portion of the well-shaped partition forms a cross-shaped flow channel below the top cover. The cross-shaped flow channel includes four radial branches extending along the radius. Each radial branch is provided with a fine crystal liquid interface, a hot liquid reflux interface and a circulating liquid interface, each fine crystal liquid interface is close to the center of the top cover, each hot liquid reflux interface is located radially outside each fine crystal liquid interface, and each circulating liquid interface is close to the inner wall of the crystallizer; Each fine crystal liquid interface is connected to the inlet pipe of the fine crystal circulation pump, the outlet of the fine crystal circulation pump is connected to the tube side inlet of the heat exchanger through the fine crystal circulation pipe, and the tube side outlet of the heat exchanger is connected to the corresponding hot material liquid reflux interface; Each circulating liquid interface is connected to the suction pipe of the liquid circulation pump, the outlet of the liquid circulation pump is connected to the tube side inlet of the external cooler through the liquid circulation pipe, the tube side outlet of the external cooler and the sodium sulfate solution feed pipe are jointly connected to the feed port of the crystallizer, and a slurry outlet is provided at the lower part of the side wall of the crystallizer.

2. The device for eliminating fine crystals in the sodium sulfate cooling crystallization process according to claim 1, wherein: The lower edge of the well-shaped partition is 2 to 6 cm away from the lower end surface of the top cover, and the closer it is to the center of the top cover, the deeper the depth of the well-shaped partition is; the closer it is to the periphery of the top cover, the shallower the depth of the well-shaped partition is.

3. The device for eliminating fine crystals in the sodium sulfate cooling crystallization process according to claim 1, wherein: The lower port of the fine crystal liquid interface is within 2 cm from the lower end surface of the top cover or is flush with the lower end surface of the top cover, the lower port of the hot material liquid reflux interface is lower than the lower edge of the well-shaped partition, and the lower port of the circulating liquid interface is lower than the lower port of the hot material liquid reflux interface.

4. The device for eliminating fine crystals in the sodium sulfate cooling crystallization process according to claim 1, 2 or 3, wherein: The tube-side outlet pipes of each heat exchanger are respectively connected to the fine crystal flushing pipes, and the outlets of each fine crystal flushing pipe are respectively connected to the tube-side inlet of the corresponding external cooler.

5. The device for eliminating fine crystals in the sodium sulfate cooling crystallization process according to claim 1, 2 or 3, wherein: The external cooler, heat exchanger, fine crystal circulation pump and liquid circulation pump are provided in four groups, corresponding to the four branches of the cross-shaped flow channel respectively.

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