Integrated evaporation crystallization system suitable for potassium sulfate fractionation

Abstract

The utility model discloses a kind of integrated evaporation crystallization systems suitable for potassium sulfate fractional salt, belong to high-efficiency energy-saving industrial technology field.The system includes the preheating unit, evaporation crystallization unit, crystal slurry processing unit and salt washing refining unit connected in turn, and after two-stage preheating of condensate preheater and non-condensing steam preheater, into forced evaporator, after heating, send into integrated crystallizer evaporation crystallization;Integrated crystallizer is equipped with discharging salt leg and bottom heat exchanger evaporator, respectively equipped with salt leg crystal slurry outlet and bottom crystal slurry outlet, both are jointly connected crystal slurry discharge pump;Crystal slurry is thick after thickening tank thickening and enters centrifuge separation, mother liquor returns system circulation, solid phase enters salt washing storage tank;Unique is, using preheated fresh feed to wash potassium sulfate crystal after centrifugation, after washing, crystal slurry is treated by salt washing thickening tank and three-in-one filter to obtain high-purity product.The system can be long-term stable operation with low energy consumption and high product purity.

Description

Technical Field

[0001] This utility model relates to an evaporation crystallization system, and more particularly to an integrated evaporation crystallization system suitable for potassium sulfate desalting, belonging to the field of high-efficiency and energy-saving industrial technology. Background Technology

[0002] Potassium sulfate is an important chloride-free potassium fertilizer and a crucial raw material for industrial production. Its primary application is in agriculture, where it serves as a high-grade potassium fertilizer, providing the two essential elements of potassium and sulfur needed by cash crops. The abundant potassium promotes photosynthesis and protein synthesis in crops, enhances their resistance to adverse conditions (such as drought, cold, and pests), and improves fruit quality (such as increasing sugar content, color, and storage life). For high-value crops like tobacco, grapes, and tea, the chloride-free nature of potassium sulfate effectively prevents the decline in crop quality caused by chloride ions, ensuring their economic value. The sulfur in potassium sulfate helps synthesize proteins and enzymes, preventing yellowing leaves and slow growth. In industrial production, potassium sulfate can also produce many derivatives, such as potassium persulfate, potassium carbonate, and potassium aluminum sulfate, meeting diverse industrial needs.

[0003] Currently, potassium sulfate is mainly produced through two methods: extraction from natural minerals and chemical reaction. The most common chemical reaction method is the Mannheim process, which utilizes potassium chloride and concentrated sulfuric acid in a high-temperature double decomposition reaction to produce potassium sulfate and hydrochloric acid as a byproduct. The equipment used is a Mannheim reactor. This technology is mature and reliable, but it consumes a large amount of energy, has strict requirements for reaction equipment, and requires significant investment. Another method involves direct extraction from natural minerals. Potassium sylvite is mined underground, the ore is crushed to a state of crystalline dissociation, and then flotation and separation are performed using a flotation machine to obtain dried potassium chloride. Potassium sulfate that meets the process requirements can then be obtained through chemical processing. The natural mineral extraction method is cumbersome, has excessively high environmental and mineral deposit requirements, and cannot be implemented on a large scale. Therefore, there is an urgent need to develop a new potassium sulfate preparation process that consumes less energy, produces less corrosive equipment, yields higher product purity, and is more environmentally friendly.

[0004] Chinese utility model patent CN206414774U discloses a high-efficiency potassium persulfate evaporation and crystallization device, including a first heating chamber, a second heating chamber, and a separation chamber. The first heating chamber contains a heat-conducting plate and a resistance wire positioned below the heat-conducting plate. A heating device is connected below the resistance wire. A second heating chamber and a circulating pump positioned below the second heating chamber are located on one side of the first heating chamber. The bottom of the second heating chamber is connected to the first heating chamber via a circulating water pipe, and the circulating pump is connected to the circulating water pipe. A steam pipe is connected to one side of the second heating chamber and above the first heating chamber. An evaporation chamber is located on one side of the second heating chamber. The self-heating first heating chamber heats the fed potassium persulfate. The heated and concentrated material enters the second heating chamber through a circulating pipe for secondary heating, generating a saturated potassium persulfate solution. Finally, it enters the evaporation chamber for evaporation and crystallization, generating a potassium persulfate slurry. The drawbacks of this technical solution are: the imported materials are not preheated, heating the materials requires more steam and electricity, resulting in low production efficiency; the steam used for heat exchange in the second heating box is generated by electric heating and evaporation in the first heating box, the steam grade is low, the heat exchange efficiency is poor, and the heat exchange tubes are prone to scaling, which affects the crystallization production efficiency.

[0005] Chinese invention patent application CN113184882A discloses a highly efficient system and method for producing potassium sulfate as a byproduct of potassium chloride brine thermal denitrification. The system includes a nanofiltration membrane system, a brine heater, a circulating heater, an evaporator, and an MVR (Medium-Vacuum Recompression) system. The inlet material sequentially passes through the nanofiltration membrane system for adsorption and filtration, then enters the brine heater for preheating. After heating, the material enters the circulating heater to exchange heat with steam, and then evaporates and crystallizes in the evaporator. The shortcomings of this technical solution are: it does not consider the influence of non-condensable steam in the circulating heater, nor does it fully utilize the residual heat from the discharged non-condensable steam, making long-term stable system operation impossible; the separator and circulating heater are two separate devices, resulting in higher costs and heat loss during material circulation. Utility Model Content

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0007] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0008] The purpose of this invention is to overcome the problems existing in the prior art and provide an integrated evaporation and crystallization system suitable for potassium sulfate desalting, which has low energy consumption, compact equipment, high product purity, and can operate stably for many years.

[0009] To solve the above technical problems, this utility model provides an integrated evaporation crystallization system suitable for potassium sulfate desalting. The system includes a feed pump, whose outlet is connected sequentially to the cold side of a condensate preheater and a non-condensable steam preheater, and then to the tube-side inlet of a forced evaporator. The outlet of the forced evaporator is connected to the material inlet of the upper crystallizer within the integrated crystallizer. The upper crystallizer has a feeding salt leg on its conical bottom sidewall, with a salt slurry outlet at its lower end. A heat exchange evaporator is connected to the center of the conical bottom of the upper crystallizer, with a bottom crystal slurry outlet at its lower end. The bottom crystal slurry outlet is also connected to the tube-side inlet of the forced evaporator via a material circulation pipe and a forced circulation pump. The salt leg crystal slurry outlet and the bottom crystal slurry outlet are connected to the crystal slurry thickening tank through the crystal slurry discharge pump. The outlet of the crystal slurry thickening tank is connected to the inlet of the centrifuge. The liquid phase outlet of the centrifuge is connected to the mother liquor tank. The bottom outlet of the mother liquor tank is connected to the material circulation pipe at the inlet of the forced circulation pump. The solid phase outlet of the centrifuge is connected to the washing salt storage tank. The cold side outlet of the non-condensable steam preheater is also connected to the washing liquid inlet of the washing salt storage tank. The bottom outlet of the washing salt storage tank is connected to the washing salt thickening tank through the washing salt circulation pump. The bottom outlet of the washing salt thickening tank is connected to the inlet of the three-in-one filter. The solid phase outlet of the three-in-one filter is connected to the qualified product discharge pipe. The liquid phase outlet of the three-in-one filter is connected to the top reflux port of the washing salt storage tank.

[0010] Furthermore, the top secondary gas outlet of the integrated crystallizer is connected to the inlet of the gas scrubbing tower via a secondary gas delivery pipe, the gas outlet of the gas scrubbing tower is connected to the inlet of the steam compressor, and the outlet of the steam compressor is connected to the shell-side inlet of the forced evaporator and the shell-side inlet of the lower heat exchange evaporator of the integrated crystallizer via a compressed steam circulation pipe.

[0011] Furthermore, the shell-side condensate outlet of the forced evaporator and the shell-side condensate outlet of the lower heat exchange evaporator of the integrated crystallizer are connected to the inlet of the condensate tank. The bottom outlet of the condensate tank is connected to the hot-side inlet of the condensate preheater via a condensate pump. The hot-side outlet of the condensate preheater is connected to the condensate recovery system.

[0012] Furthermore, the bottom circulating water outlet of the air scrubbing tower is connected to the inlet of the scrubbing tower circulating pump, and the outlet of the scrubbing tower circulating pump is connected to the spray pipe at the top of the air scrubbing tower through the scrubbing water circulating pipe; the outlet of the cooling water conveying pipe is connected to the cold side inlet of the surface condenser, and the cold side outlet of the surface condenser is connected to the scrubbing water circulating pipe.

[0013] Furthermore, the shell-side non-condensable gas outlet of the forced evaporator and the shell-side non-condensable gas outlet of the lower heat exchange evaporator of the integrated crystallizer are connected to the hot-side inlet of the non-condensable steam preheater through a non-condensable steam delivery pipe. The hot-side outlet of the non-condensable steam preheater is connected to the hot-side inlet of the surface condenser, and the hot-side outlet of the surface condenser is connected to the vacuum system.

[0014] Compared with the prior art, the advantages or beneficial effects of this utility model include at least the following: 1. This system achieves efficient separation of potassium sulfate from the mother liquor, resulting in a purity of ≥52% for powdered potassium sulfate and water-soluble potassium oxide. The product meets the standard of superior grade powdered agricultural potassium sulfate in GB / T 20406-2017 and is ready for sale. The system adopts a process of two-stage preheater + integrated evaporation crystallization + two-stage thickening centrifuge, making reasonable use of the latent heat of secondary steam, the heat of condensate, and the cleaning effect of fresh materials, thereby improving energy utilization efficiency and reducing energy consumption of potassium sulfate output by more than 15%.

[0015] 2. The integrated crystallizer in this system effectively combines the crystallizer with the forced evaporator, which effectively reduces the equipment height of the evaporation crystallization device, reduces the steel structure and equipment manufacturing costs, and also meets the restrictions on the overall height of the production device in some areas, making this crystallization device suitable for more sites at home and abroad.

[0016] 3. This system is designed with a non-condensable steam heat exchange and vacuum extraction system. A water ring vacuum pump is selected to ensure that the temperature rise is maintained within 15℃. In addition, the water seal in the water ring storage tank can absorb acid droplets in the non-condensable steam, ensuring that the vacuum discharge meets environmental protection standards.

[0017] 4. This system incorporates a salt washing process for potassium sulfate crystallization. The washing solution used in the salt washing tank is freshly fed potassium sulfate after two-stage preheating. This process can efficiently dissolve surface impurities such as potassium persulfate in centrifuged potassium sulfate crystals, reducing the amount of potassium sulfate that needs to be dissolved again. The salt washing process improves the purity and quality of the potassium sulfate product. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit this utility model. Wherein: Figure 1 This is a flowchart of the integrated evaporation crystallization system for potassium sulfate separation according to this utility model; Figure 2 This is a schematic diagram of the integrated crystallizer of this utility model; Attached reference numerals: 1. Raw material tank; 2. Condensate preheater; 3. Non-condensable steam preheater; 4. Condensate tank; 5. Forced evaporator; 6. Integrated crystallizer; 7. Gas scrubbing tower; 8. Steam compressor; 9. Surface condenser; 10. Crystal slurry thickening tank; 11. Centrifuge; 12. Mother liquor tank; 13. Wash salt thickening tank; 14. Three-in-one filter; 15. Wash salt storage tank; 6. Integrated crystallizer; 6a. Crystallizer body; 6a1. Material inlet; 6a2. Secondary steam outlet; 6a3. Wire mesh demister; 6b. Feeding salt leg; 6b1. Salt leg crystal slurry outlet; 6c. Heat exchange evaporator; 6c1. Upper non-condensable steam outlet; 6c2. Heating steam inlet; 6c3. Condensate outlet; 6c4. Bottom crystal slurry outlet; B1. Feed pump; B2. Condensate pump; B3. Forced circulation pump; B4. Crystal slurry discharge pump; B5. Washing tower circulation pump; B6. Salt washing circulation pump; G1. Feed pipe; G2. Material circulation pipe; G3. Crystal slurry discharge pipe; G4. Condensate pipe; G5. Seed crystal addition pipe; G6. Non-condensable steam conveying pipe; G7. Secondary gas conveying pipe; G8. Steam replenishment pipe; G9. Qualified product discharge pipe; G10. Cooling water conveying pipe; G11. Washing water circulation pipe. Detailed Implementation

[0019] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0021] like Figure 1 As shown, this utility model is applicable to an integrated evaporation crystallization system for potassium sulfate separation, including a raw material tank 1, a condensate preheater 2, a non-condensable steam preheater 3, a condensate tank 4, a forced evaporator 5, an integrated crystallizer 6, a gas scrubbing tower 7, a steam compressor 8, a surface condenser 9, a crystal slurry thickening tank 10, a centrifuge 11, a mother liquor tank 12, a wash salt thickening tank 13, a three-in-one filter 14, and a wash salt storage tank 15.

[0022] The bottom outlet of raw material tank 1 is connected to the inlet of feed pump B1, and the top of raw material tank 1 is connected to seed crystal addition pipe G5 for use when needed. The outlet of feed pump B1 is connected to the cold side inlet of condensate preheater 2 through feed pipe G1. The cold side outlet of condensate preheater 2 is connected to the cold side inlet of non-condensable steam preheater 3. The cold side outlet of non-condensable steam preheater 3 is connected to the tube-side inlet of forced evaporator 5. The bottom slurry outlet of integrated crystallizer 6 is connected to the inlet of forced circulation pump B3 through material circulation pipe G2. The outlet of forced circulation pump B3 is also connected to the tube-side inlet of forced evaporator 5. The tube-side outlet of forced evaporator 5 is connected to the material inlet at the top of integrated crystallizer 6. The upper crystallizer of the integrated crystallizer 6 has a feeding salt leg 6b on its conical bottom. The salt leg crystal slurry outlet 6b1 and the bottom crystal slurry outlet 6c4 of the integrated crystallizer 6 are connected to the inlet of the crystal slurry discharge pump B4. The outlet of the crystal slurry discharge pump B4 is connected to the inlet of the crystal slurry thickening tank 10 through the crystal slurry discharge pipe G3. The bottom outlet of the crystal slurry thickening tank 10 is connected to the inlet of the centrifuge 11. The liquid phase outlet of the centrifuge 11 is connected to the top inlet of the mother liquor tank 12. The bottom outlet of the mother liquor tank 12 is connected to the material circulation pipe G2 at the inlet of the forced circulation pump B3.

[0023] The solid phase outlet of centrifuge 11 is connected to the top feed inlet of the salt washing storage tank 15. The cold side outlet of the non-condensable steam preheater 3 is also connected to the washing liquid inlet of the salt washing storage tank 15. The bottom outlet of the salt washing storage tank 15 is connected to the inlet of the salt washing circulation pump B6. The outlet of the salt washing circulation pump B6 is connected to the top inlet of the salt washing thickening tank 13. The bottom outlet of the salt washing thickening tank 13 is connected to the inlet of the three-in-one filter 14. The solid phase outlet of the three-in-one filter 14 is connected to the qualified product discharge pipe G9. The liquid phase outlet of the three-in-one filter 14 is connected to the top reflux port of the salt washing storage tank 15.

[0024] like Figure 2 As shown, the upper part of the integrated crystallizer 6 is a crystallizer cylinder 6a. A material inlet 6a1 is located on the middle side wall of the crystallizer cylinder 6a. The lower part of the crystallizer cylinder 6a has a conical bottom, and a downward-extending feed salt leg 6b is connected to the side wall of the conical bottom. A salt leg crystal slurry outlet 6b1 is located at the lower end of the feed salt leg 6b. An upper cone is located at the upper end of the crystallizer cylinder 6a, and a secondary steam outlet 6a2 is located at the upper end of the upper cone. A wire mesh demister 6a3 is installed within the upper cone.

[0025] A heat exchange evaporator 6c is connected to the center outlet of the cone bottom. Multiple heat exchange tubes extending vertically are connected between the tube sheets at both ends of the heat exchange evaporator. The upper shell side of the heat exchange evaporator has an upper non-condensable steam outlet 6c1. The upper enlarged section of the shell side of the heat exchange evaporator has a heating steam inlet 6c2. The lower shell side of the heat exchange evaporator has a condensate outlet 6c3. The lower end of the heat exchange evaporator has a bottom crystal slurry outlet 6c4.

[0026] The top secondary gas outlet of the integrated crystallizer 6 is connected to the inlet of the scrubbing tower 7 via the secondary gas delivery pipe G7. The outlet of the scrubbing tower 7 is connected to the inlet of the steam compressor 8. The outlet of the steam compressor 8 is connected to the shell-side inlet of the forced evaporator 5 and the shell-side inlet of the heat exchange evaporator at the bottom of the integrated crystallizer 6 via the compressed steam circulation pipe. A steam replenishment pipe G8 is also connected to the compressed steam circulation pipe.

[0027] The bottom circulating water outlet of the gas scrubbing tower 7 is connected to the inlet of the scrubbing tower circulating pump B5, and the outlet of the scrubbing tower circulating pump B5 is connected to the spray pipe at the top of the gas scrubbing tower 7 through the scrubbing water circulation pipe G11.

[0028] The outlet of the cooling water delivery pipe G10 is connected to the cold side inlet of the surface condenser 9, and the cold side outlet of the surface condenser 9 is connected to the washing water circulation pipe G11 to supplement the washing water to the air scrubbing tower 7.

[0029] The shell-side condensate outlet of the forced evaporator 5 and the shell-side condensate outlet of the lower heat exchange evaporator of the integrated crystallizer 6 are connected to the inlet of the condensate tank 4 via condensate pipe G4. The bottom outlet of the condensate tank 4 is connected to the inlet of the condensate pump B2. The outlet of the condensate pump B2 is connected to the hot-side inlet of the condensate preheater 2. The hot-side outlet of the condensate preheater 2 is connected to the condensate recovery system.

[0030] The shell-side non-condensable gas outlet of the forced evaporator 5 and the shell-side non-condensable gas outlet of the lower heat exchange evaporator of the integrated crystallizer 6 are connected to the hot-side inlet of the non-condensable steam preheater 3 through the non-condensable steam delivery pipe G6. The hot-side outlet of the non-condensable steam preheater 3 is connected to the hot-side inlet of the surface condenser 9. The hot-side outlet of the surface condenser 9 is connected to the vacuum system.

[0031] The working process of this evaporation crystallization system is as follows: Raw material tank 1 is used to store the potassium sulfate solution transported upstream. The concentration of the potassium sulfate in the feed is 15%, and the temperature is approximately 30°C. The liquid in raw material tank 1 is transported to the potassium sulfate evaporation and crystallization system through feed pipe G1 and feed pump B1. In order to ensure that the solution entering the system is maintained at a high temperature, a two-stage preheating system is designed, consisting of a condensate preheater 2 and a non-condensable steam preheater 3. After two-stage preheating, the temperature of the potassium sulfate material can reach 85°C, saving system steam consumption and reducing the operating cost of the unit.

[0032] After preheating, the potassium sulfate material is heated in the tubes of the forced evaporator 5 and then enters the integrated crystallizer 6 for evaporation and crystallization. When the solid-liquid ratio of the crystal slurry at the bottom of the cone reaches 10-20%, it is discharged through the crystal slurry outlet pipe G3. The undischarged mother liquor is returned to the crystallization chamber through the material circulation pipe G2 and the forced circulation pump B3 to achieve continuous crystallization. The potassium sulfate material is heated in two stages by the forced evaporator 5 and the heat exchange evaporator 6c of the integrated crystallizer 6, and evaporation and crystallization take place in the top crystallization chamber of the integrated crystallizer 6, avoiding scaling of the material in the heat exchange evaporator tubes, which would affect the heat exchange efficiency.

[0033] When the solid-liquid ratio of the potassium sulfate solution reaches 18% or higher after evaporation and crystallization, the potassium sulfate slurry needs to be collected promptly to prevent system blockage and clumping. The potassium sulfate slurry has two outlets: a salt-leg outlet 6b1 and a bottom outlet 6c4, which serve as backups for each other, increasing the system's operational flexibility and continuous operating time. The salt-leg outlet 6b1 and the bottom outlet 6c4 of the integrated crystallizer 6 are connected to the inlet of the slurry discharge pump B4, and the potassium sulfate slurry is transported to the slurry thickening tank 10 for crystal formation and precipitation via the slurry discharge pipe G3. The bottom slurry of the slurry thickening tank 10 is transported to the centrifuge 11 for solid-liquid separation via the discharge pipe. The liquid phase discharge from the centrifuge 11 enters the top inlet of the mother liquor tank 12 via a pipeline. The potassium sulfate mother liquor in the mother liquor tank 12 returns to the material circulation pipe G2 via a pipeline, and then undergoes a new crystallization cycle with the forced circulation pump B3.

[0034] The solid phase discharge from centrifuge 11 enters the washing salt storage tank 15 via a chute. Fresh potassium sulfate solution from feed pipe G1 enters the washing salt storage tank 15 to wash the solid potassium sulfate, removing solid impurities such as potassium persulfate covering the surface of the potassium sulfate, and then redissolves it. The potassium sulfate solution discharged from the bottom of the washing salt storage tank 15 is pumped into the top inlet of the washing salt thickening tank 13 by washing salt circulation pump B6. After crystallization and precipitation in the washing salt thickening tank 13, the potassium sulfate solution flows into the three-in-one filter 14 for solid-liquid separation. The solid phase discharge from the three-in-one filter 14 is transported to the packaging machine for product packaging and external shipment through the qualified product discharge pipe G9. The liquid phase discharge from the three-in-one filter 14 returns to the top inlet of the washing salt storage tank 15 to mix and dissolve with the dry potassium sulfate material flowing in from centrifuge 11.

[0035] The condensate discharged from the shell side of the forced evaporator 5 and the lower condensate outlet 6c3 of the integrated crystallizer 6 flows into the condensate tank 4 through the condensate pipe G4. The condensate is pumped out by the condensate pump B2 and enters the hot side of the condensate preheater 2 to preheat the fresh solution entering the system, reducing the steam loss of the subsequent forced evaporator 5. The condensate after heat exchange is then used in other devices for reasonable utilization.

[0036] The non-condensable gas from the shell side of the forced evaporator 5 and the integrated crystallizer 6 enters the hot side of the non-condensable gas preheater 3 via the non-condensable gas delivery pipe G6 to preheat the fresh solution a second time, making full use of the residual heat of the non-condensable gas. The preheated non-condensable gas enters the hot side of the surface condenser 9 for cooling and is then discharged, ensuring that the system vacuum is maintained above -30 kPa. The negative pressure evaporation of the device can save steam consumption and compressor power.

[0037] The secondary gas discharged from the top of the integrated crystallizer 6 enters the gas scrubbing tower 7 through the secondary gas delivery pipe G7 for washing and cleaning. After being scrubbed by the gas scrubbing tower 7, the secondary gas is pressurized and heated by the steam compressor 8 and then re-enters the shell side of the forced evaporator 5 and the heating steam inlet 6c2 of the integrated crystallizer 6 through the compressed steam circulation pipe. Considering that there will be some loss of secondary gas, the compressed steam is supplemented through the live steam replenishment pipe G8 to ensure the heat source required for the separation of qualified potassium sulfate product salt.

[0038] The system cooling water enters the cold side of the surface condenser 9 via the cooling water delivery pipe G10 to cool the non-condensable gas. Then, it enters the washing water circulation pipe G11 via the cooling water delivery pipe G10, and finally enters the washing water system of the gas scrubbing tower 7. The washing water at the bottom of the gas scrubbing tower is circulated by the washing tower circulation pump B5 to spray and adsorb the secondary gas inside the gas scrubbing tower for cleaning.

[0039] The above description is merely a preferred embodiment of the present utility model, showing and describing the basic principles, main features, and advantages of the present utility model. It is not intended to limit the scope of patent protection of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. In addition to the above embodiments, the present utility model may have other implementations without departing from the spirit and scope of the present utility model. Various changes and improvements to the present utility model are also possible. All technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present utility model. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents. Technical features not described in the present utility model can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. An integrated evaporation crystallization system suitable for potassium sulfate desalting, comprising a feed pump (B1), characterized in that, The outlet of the feed pump (B1) is connected to the tube-side inlet of the forced evaporator (5) via the cold side of the condensate preheater (2) and the non-condensable steam preheater (3). The outlet of the forced evaporator (5) is connected to the material inlet of the upper crystallizer in the integrated crystallizer (6). The cone bottom sidewall of the upper crystallizer is provided with a feeding salt leg (6b), and the lower end of the feeding salt leg (6b) is provided with a salt leg crystal slurry outlet (6b1). The center of the cone bottom of the upper crystallizer is connected to a heat exchange evaporator (6c), and the lower end of the heat exchange evaporator (6c) is provided with a bottom crystal slurry outlet (6c4). The bottom crystal slurry outlet (6c4) is also connected to the tube-side inlet of the forced evaporator (5) via the material circulation pipe (G2) and the forced circulation pump (B3). The salt leg crystal slurry outlet (6b1) and the bottom crystal slurry outlet (6c4) are connected to the crystal slurry thickening tank (10) through the crystal slurry discharge pump (B4). The outlet of the crystal slurry thickening tank (10) is connected to the inlet of the centrifuge (11). The liquid phase outlet of the centrifuge (11) is connected to the mother liquor tank (12). The bottom outlet of the mother liquor tank (12) is connected to the material circulation pipe (G2) at the inlet of the forced circulation pump (B3). The solid phase outlet of the centrifuge (11) is connected to the washing salt storage tank (15). The cold side outlet of the non-condensable steam preheater (3) is also connected to the washing liquid inlet of the washing salt storage tank (15). The bottom outlet of the washing salt storage tank (15) is connected to the washing salt thickening tank (13) through the washing salt circulation pump (B6). The bottom outlet of the washing salt thickening tank (13) is connected to the inlet of the three-in-one filter (14). The solid phase outlet of the three-in-one filter (14) is connected to the qualified product discharge pipe (G9). The liquid phase outlet of the three-in-one filter (14) is connected to the top return port of the washing salt storage tank (15).

2. The integrated evaporation crystallization system for potassium sulfate separation according to claim 1, characterized in that: The top secondary gas outlet of the integrated crystallizer (6) is connected to the inlet of the scrubbing tower (7) through the secondary gas delivery pipe (G7). The outlet of the scrubbing tower (7) is connected to the inlet of the steam compressor (8). The outlet of the steam compressor (8) is connected to the shell-side inlet of the forced evaporator (5) and the shell-side inlet of the lower heat exchange evaporator (6c) of the integrated crystallizer (6) through the compressed steam circulation pipe.

3. The integrated evaporation crystallization system for potassium sulfate separation according to claim 1, characterized in that: The shell-side condensate outlet of the forced evaporator (5) and the shell-side condensate outlet of the lower heat exchange evaporator of the integrated crystallizer (6) are connected to the inlet of the condensate tank (4). The bottom outlet of the condensate tank (4) is connected to the hot-side inlet of the condensate preheater (2) through the condensate pump (B2). The hot-side outlet of the condensate preheater (2) is connected to the condensate recovery system.

4. The integrated evaporation crystallization system for potassium sulfate separation according to claim 2, characterized in that: The bottom circulating water outlet of the gas scrubbing tower (7) is connected to the inlet of the scrubbing tower circulating pump (B5), and the outlet of the scrubbing tower circulating pump (B5) is connected to the spray pipe at the top of the gas scrubbing tower (7) through the washing water circulating pipe (G11); the outlet of the cooling water conveying pipe (G10) is connected to the cold side inlet of the surface condenser (9), and the cold side outlet of the surface condenser (9) is connected to the washing water circulating pipe (G11).

5. The integrated evaporation crystallization system for potassium sulfate fractionation according to any one of claims 1 to 4, characterized in that: The shell-side non-condensable gas outlet of the forced evaporator (5) and the shell-side non-condensable gas outlet of the lower heat exchange evaporator of the integrated crystallizer (6) are connected to the hot-side inlet of the non-condensable steam preheater (3) through the non-condensable steam delivery pipe (G6). The hot-side outlet of the non-condensable steam preheater (3) is connected to the hot-side inlet of the surface condenser (9). The hot-side outlet of the surface condenser (9) is connected to the vacuum system.

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