Steam powder tail gas waste heat recovery refrigeration coupling DTB crystallization system

Abstract

A steam powder tail gas waste heat recovery refrigeration coupling DTB crystallization system comprises steam powder process equipment for conducting steam flow crushing on titanium dioxide materials through steam, crystallization process equipment for crystallizing titanium liquid and a refrigerating unit. The refrigerating unit is externally connected with a cooling circulation mechanism, and a generator, an absorber, a condenser and an evaporator are arranged in the refrigerating unit. And the absorber, the condenser and the cooling circulation mechanism are circularly connected to form a second circulation. And a second cooling medium is filled in the second circulation. The steam powder process equipment comprises a steam flow crusher and a steam powder tail gas spray tower, and the steam powder tail gas spray tower is circularly connected with the generator to form a first cycle. And a third cycle is arranged in the crystallization process equipment, and a third cooling medium is filled in the third cycle. According to the utility model, the refrigerating unit is matched with the three-stage DTB crystallization process, so that the efficient utilization of energy is realized, and the retention time and the crystal growth time in the crystallization process are effectively controlled.

Description

Technical Field

[0001] The utility model belongs to the technical field of titanium dioxide production equipment, and specifically relates to a DTB crystallization system for recovering waste heat from exhaust gas of steam and powder and refrigerating and coupling. Background Art

[0002] The titanium dioxide product consumes 1.25~1.35 tons of high-pressure superheated steam in the steam-powder process. The steam quality is 280~300℃ and 2.0~2.5Mpa. During the crushing process, the high-pressure steam provides power to entrain the titanium dioxide material in the steam flow mill for high-speed collision crushing. After crushing, the material is classified by the grading sleeve and then enters the bag filter for dust removal. The collected titanium dioxide enters the subsequent finished product packaging process. The high-temperature steam as the crushing working medium enters the spray tower for spray cooling after steam-solid separation in the bag dust collector. After cooling, the hot water is used for water washing (three washing) process. Most of the remaining hot water is cooled and circulated by cooling tower circulation. A large amount of low-grade heat generated during this period cannot be used and needs to be cooled and discharged. The annual heat emission is equivalent to about 468,000 tons of standard coal, resulting in very serious waste.

[0003] Before the sulfuric acid method titanium dioxide acid hydrolysis concentration, the titanium liquid is cooled and crystallized to remove ferrous sulfate in the titanium liquid, ensuring that the iron-titanium ratio of the titanium liquid before concentration is within the range of 0.28~0.32. Currently, there are three crystallization methods, VCE crystallization, Oslo crystallization, and vacuum crystallization, which are used in actual production. The first two are continuous production, and vacuum crystallization is intermittent batch production. Regardless of the above crystallization method, there are problems such as small crystallization ions, short crystallization process crystallization cycle, small crystal particle size, and uncontrollable crystal particle size. In addition, a large amount of 5~7℃ cold water is required for cooling and cooling in the crystallization process. In traditional technology, this part of energy is not only not coupled and cascaded, but the consumed steam needs to be further cooled to meet the process requirements, and a large amount of energy waste and consumption is caused. Utility Model Content

[0004] In order to solve the above technical problems, the utility model solves them through the following technical solutions.

[0005] A steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system comprises steam-powder process equipment for steam flow pulverizing titanium dioxide materials using steam, crystallization process equipment for crystallizing titanium liquid and a refrigeration unit.

[0006] The refrigeration unit is externally connected to a cooling circulation mechanism, and a generator, an absorber, a condenser and an evaporator are arranged inside the refrigeration unit. The absorber, the condenser and the cooling circulation mechanism are cyclically connected to form a second cycle. The second cycle is internally filled with a second cooling medium.

[0007] The steam-powder process equipment includes a steam flow pulverizer and a steam-powder tail gas spray tower, and the steam-powder tail gas spray tower is cyclically connected with the generator to form a first cycle. Steam entrains titanium dioxide materials into the steam flow pulverizer for steam flow pulverization, and the steam that has completed the steam flow pulverization enters the steam-powder tail gas spray tower and is cooled and circulated through the generator of the refrigeration unit.

[0008] The crystallization process equipment includes a primary crystallization mechanism, a secondary crystallization mechanism and a tertiary crystallization mechanism. The primary crystallization mechanism includes a primary crystallizer and a primary cooler, the secondary crystallization mechanism includes a secondary crystallizer and a secondary cooler, and the tertiary crystallization mechanism includes a tertiary crystallizer and a tertiary cooler. The primary crystallizer, the secondary crystallizer and the tertiary crystallizer are connected in sequence, the primary crystallizer is connected to the intermediate titanium liquid tank, and the tertiary crystallizer is connected to the crystallization titanium liquid tank. The primary cooler is cooled by titanium liquid, the secondary cooler is cyclically connected to the evaporator to form a third cycle, the third cycle is filled with a third cooling medium, and the tertiary cooler is connected in parallel with the secondary cooler.

[0009] Preferably, the steam-powder process equipment further comprises a steam-powder bag filter, which is arranged between the steam flow pulverizer and the steam-powder tail gas spray tower. The steam-powder bag filter is connected to the finished product packaging system, and a star-shaped feeder is installed at the bottom of the steam-powder bag filter.

[0010] Preferably, a hot water tank, a hot water pump, and a safety filter are sequentially installed between the steam-powder tail gas spray tower and the generator, and the flow direction of the second cycle is steam-powder tail gas spray tower-hot water tank-hot water pump-safety filter-generator-steam-powder tail gas spray tower. The safety filter is connected to the production system, and a pressure transmitter is arranged inside the safety filter.

[0011] Preferably, the steam-powder process equipment further comprises a steam-powder tail gas condenser, a steam-powder tail gas fan and a desalted water pump. The steam-powder tail gas condenser is connected to the steam-powder tail gas spray tower, and the steam-powder tail gas condenser is provided with an exhaust port, which is connected to the steam-powder tail gas fan. The desalted water pump is connected to the steam-powder tail gas condenser.

[0012] Preferably, the inlets of the primary crystallizer, the secondary crystallizer and the tertiary crystallizer are respectively provided with a primary feed pump, a secondary feed pump and a tertiary feed pump. The outlet of the crystallization titanium liquid tank is provided with a crystallization titanium liquid pump. The bottoms of the primary crystallizer, the secondary crystallizer and the tertiary crystallizer are all provided with an axial flow pump.

[0013] Preferably, the air inlets of the primary cooler, the secondary cooler and the tertiary cooler are respectively connected to the primary crystallizer, the secondary crystallizer and the tertiary crystallizer, and the air outlets of the primary cooler, the secondary cooler and the tertiary cooler are respectively connected to the primary vacuum pump group, the secondary vacuum pump group and the tertiary vacuum pump group.

[0014] Preferably, the inlet of the primary cooler is connected to the titanium clear liquid tank, and the outlet of the primary cooler is connected to the MVR concentration system.

[0015] Preferably, the titanium dioxide material entering the steam pulverizer comes from a flash drying silo.

[0016] Preferably, the primary crystallizer, the secondary crystallizer and the tertiary crystallizer are all provided with a liquid level meter, a temperature sensor and a pressure sensor.

[0017] Preferably, the refrigeration unit is a hot water type lithium bromide absorption chiller.

[0018] Compared with the prior art, the utility model has the following technical advantages: the utility model adopts a refrigeration unit in combination with a three-stage DTB crystallization process, and the exhaust steam of the steam-powder process is sprayed with desalted water to generate hot water at a temperature of 75-80°C. The hot water after spraying is pumped to the refrigeration unit to produce cold water at 5-7°C, and the cold water at 5-7°C is circulated to cool the secondary steam of the vacuum flash process of the DTB crystallizer. Through the "heart" function of the refrigeration unit between the two processes, the "cold and hot" energy conversion between the processes is realized, which not only recycles the high-temperature exhaust steam of the steam-powder process, but also cleverly uses the refrigeration unit to convert the waste heat into refrigerant for the use of the DTB crystallization system, replacing the traditional electric refrigeration unit to realize the cascade utilization of steam-powder steam, reduce the operating power consumption of the DTB crystallization system, and realize the efficient use of energy. The DTB crystallization process is introduced and the three-stage crystallization process is adopted, which effectively controls the residence time and crystal growth time of the crystallization process, ensures the particle size of ferrous crystals, and effectively solves the problem of heat exchanger blockage in the Oslo crystallization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0020] Figure 2 It is a schematic diagram of the process configuration of the steam-powder process equipment, refrigeration unit, and cooling cycle mechanism.

[0021] Figure 3 This is a schematic diagram of the process configuration of the crystallization process equipment, refrigeration unit, and cooling cycle mechanism.

[0022] The following is a description of the markings in the accompanying drawings of the specification:

[0023] 1. Steam flow pulverizer; 2. Steam powder bag filter; 3. Star-shaped feeder; 4. Steam powder exhaust spray tower; 5. Steam powder exhaust condenser; 6. Steam powder exhaust fan; 7. Desalted water pump; 8. Hot water tank; 9. Hot water pump; 10. Refrigeration unit; 11. Cooling tower; 12. Cooling pump; 13. Cold water circulation pump; 14. Cold water circulation tower; 15. Three-stage cooler; 16. Three-stage vacuum pump group; 17. Three-stage crystallizer; 18. Crystallization titanium liquid tank; 19. Crystallization titanium liquid pump; 20. Three-stage feed pump; 21. Secondary crystallizer; 22. Secondary cooler; 23. Secondary vacuum pump group; 24. Secondary feed pump; 25. Primary crystallizer; 26. Primary cooler; 27. Primary vacuum pump group; 28. Primary feed pump; 29. ​​Intermediate titanium liquid tank; 30. Safety filter. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] In the following embodiments, the same or similar reference numerals throughout represent the same or similar components or components with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limitations on the present invention.

[0026] In the description of the present utility model, it should be understood that the terms: center, longitudinal, transverse, length, width, thickness, up, down, front, back, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise, etc. indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present utility model and simplifying the description, and therefore cannot be understood as limiting the present utility model. In addition, the terms: first, second, etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features shown. In the description of the present utility model, unless otherwise clearly specified and limited, the terms: install, connect, connect, etc. should be understood in a broad sense, and ordinary technicians in this field can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0027] Reference Figures 1 to 3 A steam-powder exhaust waste heat recovery refrigeration coupled DTB crystallization system includes a steam-powder process equipment for steam flow pulverizing titanium dioxide materials using steam, a crystallization process equipment for crystallizing titanium liquid, and a refrigeration unit 10, wherein the refrigeration unit 10 is a hot water type lithium bromide absorption chiller.

[0028] The refrigeration unit 10 is externally connected to a cooling circulation mechanism, and a generator, an absorber, a condenser and an evaporator are arranged in the refrigeration unit 10. The absorber, the condenser and the cooling circulation mechanism are cyclically connected to form a second cycle. A second cooling medium is installed inside the second cycle, and the cooling circulation mechanism includes a cold water circulation pump 13 and a cold water circulation tower 14.

[0029] The steam-powder process equipment includes a steam-flow pulverizer 1 and a steam-powder tail gas spray tower 4, and the steam-powder tail gas spray tower 4 is connected to the generator cycle to form a first cycle. The titanium dioxide material entering the steam-flow pulverizer 1 comes from the flash drying silo, and the steam entrains the titanium dioxide material into the steam-flow pulverizer 1 for steam-flow pulverization. The steam that completes the steam-flow pulverization enters the steam-powder tail gas spray tower 4 and is cooled by the generator of the refrigeration unit 10. Circulation.

[0030] The crystallization process equipment includes a primary crystallization mechanism, a secondary crystallization mechanism and a tertiary crystallization mechanism. The primary crystallization mechanism includes a primary crystallizer 25 and a primary cooler 26, the secondary crystallization mechanism includes a secondary crystallizer 21 and a secondary cooler 22, and the tertiary crystallization mechanism includes a tertiary crystallizer 17 and a tertiary cooler 15. The primary crystallizer 25, the secondary crystallizer 21 and the tertiary crystallizer 17 are connected in sequence, the primary crystallizer is connected to the intermediate titanium liquid tank 29, and the tertiary crystallizer 17 is connected to the crystallization titanium liquid tank 18. The primary cooler 26 is cooled by titanium liquid, the secondary cooler 22 is connected to the evaporator cycle to form a third cycle, the third cycle is filled with a third cooling medium, and the tertiary cooler 15 is connected in parallel with the secondary cooler 22.

[0031] Specifically, the steam-powder process equipment also includes a steam-powder bag filter 2, which is arranged between the steam flow pulverizer 1 and the steam-powder tail gas spray tower 4. The steam-powder bag filter 2 is connected to the finished product packaging system, and a star-shaped feeder 3 is installed at the bottom of the steam-powder bag filter 2. A hot water tank 8, a hot water pump 9, and a security filter 30 are sequentially installed between the steam-powder tail gas spray tower 4 and the generator, and the flow direction of the second cycle is steam-powder tail gas spray tower 4-hot water tank 8-hot water pump 9-security filter 30-generator-steam-powder tail gas spray tower 4. The security filter 30 is connected to the production system. The steam-powder process equipment also includes a steam-powder tail gas condenser 5, a steam-powder tail gas fan 6 and a desalted water pump 7. The steam-powder tail gas condenser 5 is connected to the steam-powder tail gas spray tower 4, and the steam-powder tail gas condenser 5 is provided with an exhaust port, which is connected to the steam-powder tail gas fan 6. The desalted water pump 7 is connected to the steam-powder tail gas condenser 5.

[0032] The steam flow pulverization process of the steam-powder process equipment is as follows: high-temperature and high-pressure steam and titanium dioxide material steam flow pulverizer 1 work chamber, high-temperature and high-pressure steam consumes kinetic energy in the work chamber and becomes slightly negative pressure (-3500~-4500pa) high-temperature exhaust steam, exhaust steam and titanium dioxide material enter the steam-powder bag filter 2 for steam-solid separation, exhaust gas with a temperature of 140~160°C after separation enters the steam-powder exhaust gas spray tower 4 for spraying, the top of the steam-powder exhaust gas spray tower 4 is provided with an atomizing nozzle, desalted water is used for spraying, 140~160°C steam-powder steam contacts with atomized desalted water and condenses rapidly to produce 75~80°C high-temperature hot water, hot water is discharged to the hot water tank 8 through the bottom outlet of the steam-powder exhaust gas spray tower 4, in order to ensure the stability of the outlet water temperature and the efficient operation of the chiller, the bottom outlet pipe of the powder exhaust gas spray tower is provided with a thermometer, and the temperature is interlocked with the frequency of the hot water pump 9. The hot water temperature is controlled at 75~80°C by adjusting the spraying water volume. In order to ensure the outlet water temperature of the steam-powder exhaust gas spray tower 4, the exhaust gas (gas phase) temperature after spraying by the steam-powder exhaust gas spray tower 4 is about 65-70°C, and a steam-powder exhaust gas condenser 5 is arranged in series after the steam-powder exhaust gas spray tower 4, and the steam-powder exhaust gas condenser 5 further cools the exhaust gas.

[0033] Specifically, the steam-powder tail gas condenser 5 uses desalted water for heat exchange to further cool the tail gas after spraying to ensure the working requirements of the system. The desalted water after heat exchange is used for three-wash water, thereby realizing further recovery of the heat of the tail gas. The steam-powder tail gas condenser 5 is provided with an exhaust port, which is connected to the steam-powder tail gas fan 6. The non-condensable gas of the system is discharged through the power of the steam-powder tail gas fan 6, and at the same time, negative pressure working conditions are provided for the packaging system, so that the packaging system operates under negative pressure. The utility model adopts two-stage cooling for the steam used for steam flow crushing, which not only realizes the step-by-step utilization of energy, but also ensures the negative pressure of the system.

[0034] Among them, the function of the safety filter 30 is to prevent the steam powder bag filter 2 from being damaged and leaking powder, which will cause the desalted water for circulating spraying to be contaminated, thereby clogging the heat exchange tube of the chiller. A pressure transmitter is provided on the safety filter 30. When the pressure reaches the set value, it will automatically backwash, and the collected titanium dioxide material will be returned to the production system.

[0035] The utility model introduces the DTB crystallization process for the crystallization of ferrous sulfate, adopts a three-stage segmented crystallization control technology, utilizes a DTB crystallizer set by steam-powder waste heat refrigeration coupling, and three crystallizers are set in three stages in series. The material temperature is controlled by three different crystallization vacuum pressures, thereby realizing the energy ladder utilization of the evaporative tail gas cooler. Specifically, the inlets of the primary crystallizer 25, the secondary crystallizer 21, and the tertiary crystallizer 17 are respectively provided with a primary feed pump 28, a secondary feed pump 24, and a tertiary feed pump 20. The outlet of the crystallization titanium liquid tank 18 is provided with a crystallization titanium liquid pump 19. The bottoms of the primary crystallizer 25, the secondary crystallizer 21, and the tertiary crystallizer 17 are all provided with axial flow pumps. The air inlets of the primary cooler 26, the secondary cooler 22 and the tertiary cooler 15 are respectively connected to the primary crystallizer 25, the secondary crystallizer 21 and the tertiary crystallizer 17, and the air outlets of the primary cooler 26, the secondary cooler 22 and the tertiary cooler 15 are respectively connected to the primary vacuum pump group 27, the secondary vacuum pump group 23 and the tertiary vacuum pump group 16. The inlet of the primary cooler 26 is connected to the titanium clear liquid tank, and the outlet of the primary cooler 26 is connected to the MVR concentration system.

[0036] The crystallization process of the crystallization process equipment is as follows: the primary crystallizer 25 controls the material temperature at 38~42°C, and the intermediate titanium liquid with a temperature of 65°C is driven into the primary crystallizer 25 by the primary feed pump 28, and rapidly flashes under vacuum conditions with a pressure of 6.27~6.5kpa, and evaporation produces secondary steam at a temperature of about 33~37°C, and the secondary steam enters the primary cooler 26 for cooling. The primary cooler 26 is cooled by clear titanium liquid. After cooling and heat exchange, the temperature of the clear titanium liquid increases from 15~20°C to 25~30°C and enters the titanium liquid MVR concentration process.

[0037] The material after cooling in the primary crystallizer 25 enters the secondary crystallizer 21 through the secondary feed pump 24. The control pressure of the secondary crystallizer 21 is 2.64~2.8kpa, and the material temperature is 27~30℃. Under this working condition, a large amount of ferrous sulfate in the titanium liquid is rapidly precipitated, and it is in a dynamic equilibrium stage of crystal precipitation and dissolution. Small crystal centers are continuously precipitated and grown, and are continuously discharged from the top of the axial flow pump under the action of the bottom axial flow pump. Large-grained crystals settle to the bottom of the crystallizer due to gravity and are pumped to the tertiary crystallizer 17 through the tertiary feed pump 20 for further crystallization and growth. Fine-grained crystals enter from the axial flow pump, are continuously grown under stirring and then discharged. The secondary steam generated by the secondary crystallizer 21 enters the secondary cooler 22 for cooling. The discharge of the secondary crystallizer 21 is pumped into the tertiary crystallizer 17 through the tertiary evaporation feed pump. The tertiary crystallizer 17 controls the pressure at 1.07~1.15Kpa, and the liquid phase material temperature is 18~20°C. The material repeats the circulation process of the secondary crystallizer 21 in the tertiary crystallizer 17, and the crystal particles grow further. The tertiary crystallizer 17 produces secondary steam at 8~10°C, and the secondary steam enters the tertiary cooler 15 for cooling under vacuum suction. The crystals that meet the process requirements are discharged from the discharge along with the titanium liquid into the crystallization titanium liquid tank 18, and are pumped to the ferrous separation process by the crystallization titanium liquid pump 19 for ferrous separation.

[0038] Among them, the secondary cooler 22 and the tertiary cooler 15 are cooled by the third cooling medium, and the third cooling medium is the circulating cold water of 5~7℃ from the refrigeration unit 10. The non-condensable gas generated in the primary cooler 26, the secondary cooler 22 and the tertiary cooler 15 is condensed and emptied through the primary vacuum pump group 27, the secondary vacuum pump group 23 and the tertiary vacuum pump group 16 respectively. The utility model adopts a three-stage series design to realize continuous automatic crystallization, and the residence time of the material in the crystallizer can be controlled by adjusting the discharge amount, thereby realizing the control of the crystal particle size.

[0039] Preferably, the first-stage crystallizer 25, the second-stage crystallizer 21 and the third-stage crystallizer 17 are all provided with liquid level gauges, which can control the frequency of the first-stage feed pump 28, the second-stage feed pump 24 and the third-stage feed pump 20 through the liquid level to achieve liquid level stability in the crystallizer, and the first-stage crystallizer 25, the second-stage crystallizer 21 and the third-stage crystallizer 17 are all provided with temperature sensors and pressure sensors at the top to display the working temperature and pressure in the crystallizer. The first-stage vacuum pump group 27, the second-stage vacuum pump group 23 and the third-stage vacuum pump group 16 are all Roots vacuum pumps.

[0040] Compared with the prior art, the utility model has the following technical advantages:

[0041] 1. The problem of step-by-step utilization of the waste heat of exhaust steam from the steam-powder process for refrigeration is solved. By adopting 10 two-stage spraying of refrigeration units, the heat of exhaust steam from the steam-powder process is utilized step by step.

[0042] 2. Solved the problems of fine ferrous sulfate crystal particles, difficult disc separation, and high residual titanium in ferrous sulfate after centrifugal separation in the existing crystallization technology. Taking advantage of the characteristics of the DTB crystallization process (essentially coarser crystal particles than other crystallization processes, convenient particle size control), the three-stage crystallization process is combined with the ferrous sulfate crystallization dynamics to be set in series, and the crystallization evaporation temperature and discharge rate of each stage of the three-stage crystallizer 17 are controlled to achieve the process requirements of coarse ferrous sulfate crystal particles and good filtration performance. After centrifugal separation, the residual titanium in ferrous sulfate is less than 0.3%, with significant economic benefits, which indirectly improves the purity of ferrous sulfate, especially reduces the ferrous purification cost of factories producing iron phosphate.

[0043] 3. The problem that the existing sulfuric acid method titanium dioxide crystallization process cannot run continuously for a long time is solved. The utility model adopts PLC programming and DCS communication control technology to enable the system to achieve one-key start and continuous operation.

[0044] 4. The problem of low vacuum pressure has been solved. The system has introduced a Roots vacuum pump unit to replace the existing general water ring vacuum pump unit. The Roots vacuum pump unit can provide higher vacuum negative pressure than the water ring vacuum pump unit, and can better meet the crystallizer's requirements for high vacuum negative pressure and low air extraction volume.

[0045] 5. The problem of secondary steam energy recovery in the primary crystallizer 25 is solved. The primary cooler 26 is cooled by titanium clear liquid. After cooling, the temperature of the titanium clear liquid rises from 15-20°C to 25-30°C, and the temperature of the titanium liquid rises by 10°C, saving the steam consumption of subsequent MVR concentration.

[0046] The protection scope of the present invention includes but is not limited to the above embodiments. The protection scope of the present invention shall be based on the claims. Any replacement, deformation, and improvement of the technology that can be easily thought of by technicians in this field shall fall within the protection scope of the present invention.

Claims

1. A steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system, characterized in that: It includes steam-powder process equipment for steam-flow pulverizing titanium dioxide materials, crystallization process equipment for crystallizing titanium liquid, and a refrigeration unit (10); The refrigeration unit (10) is externally connected to a cooling circulation mechanism, and a generator, an absorber, a condenser and an evaporator are arranged inside the refrigeration unit (10); the absorber, the condenser and the cooling circulation mechanism are cyclically connected to form a second cycle; the second cycle is filled with a second cooling medium; The steam-powder process equipment comprises a steam flow pulverizer (1) and a steam-powder tail gas spray tower (4), wherein the steam-powder tail gas spray tower (4) is cyclically connected to the generator to form a first cycle; steam entrains titanium dioxide material into the steam flow pulverizer (1) for steam flow pulverization, and steam that has completed the steam flow pulverization enters the steam-powder tail gas spray tower (4) and is cooled and circulated through the generator of the refrigeration unit (10); The crystallization process equipment includes a primary crystallization mechanism, a secondary crystallization mechanism and a tertiary crystallization mechanism; The primary crystallization mechanism comprises a primary crystallizer (25) and a primary cooler (26), the secondary crystallization mechanism comprises a secondary crystallizer (21) and a secondary cooler (22), and the tertiary crystallization mechanism comprises a tertiary crystallizer (17) and a tertiary cooler (15); the primary crystallizer (25), the secondary crystallizer (21) and the tertiary crystallizer (17) are connected in sequence, the primary crystallizer is connected to an intermediate titanium liquid tank (29), and the tertiary crystallizer (17) is connected to a crystallization titanium liquid tank (18); the primary cooler (26) is cooled by titanium liquid, the secondary cooler (22) is cyclically connected to an evaporator to form a third cycle, the third cycle is filled with a third cooling medium, and the tertiary cooler (15) is connected in parallel with the secondary cooler (22).

2. The DTB crystallization system for recovering waste heat from exhaust gas of steam and powder according to claim 1 is characterized in that: The steam-powder process equipment further comprises a steam-powder bag filter (2), wherein the steam-powder bag filter (2) is arranged between the steam flow pulverizer (1) and the steam-powder tail gas spray tower (4); the steam-powder bag filter (2) is connected to the finished product packaging system, and a star-shaped feeder (3) is installed at the bottom of the steam-powder bag filter (2).

3. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1 is characterized in that: A hot water tank (8), a hot water pump (9), and a safety filter (30) are sequentially installed between the steam-powder exhaust gas spray tower (4) and the generator, and the flow direction of the second cycle is the steam-powder exhaust gas spray tower (4) - hot water tank (8) - hot water pump (9) - safety filter (30) - generator - steam-powder exhaust gas spray tower (4); The safety filter (30) is connected to a production system, and a pressure transmitter is arranged inside the safety filter (30).

4. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1 is characterized in that: The steam-powder process equipment further comprises a steam-powder tail gas condenser (5), a steam-powder tail gas fan (6) and a desalted water pump (7); the steam-powder tail gas condenser (5) is connected to the steam-powder tail gas spray tower (4); the steam-powder tail gas condenser (5) is provided with an exhaust port, and the exhaust port is connected to the steam-powder tail gas fan (6); the desalted water pump (7) is connected to the steam-powder tail gas condenser (5).

5. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1 is characterized in that: A primary feed pump (28), a secondary feed pump (24) and a tertiary feed pump (20) are respectively arranged at the feed inlets of the primary crystallizer (25), the secondary crystallizer (21) and the tertiary crystallizer (17); a crystallization titanium liquid pump (19) is arranged at the discharge port of the crystallization titanium liquid tank (18); and an axial flow pump is arranged at the bottom of the primary crystallizer (25), the secondary crystallizer (21) and the tertiary crystallizer (17).

6. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1 is characterized in that: The air inlets of the primary cooler (26), the secondary cooler (22) and the tertiary cooler (15) are respectively connected to the primary crystallizer (25), the secondary crystallizer (21) and the tertiary crystallizer (17); and the air outlets of the primary cooler (26), the secondary cooler (22) and the tertiary cooler (15) are respectively connected to the primary vacuum pump group (27), the secondary vacuum pump group (23) and the tertiary vacuum pump group (16).

7. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1 is characterized in that: The inlet of the primary cooler (26) is connected to the titanium clear liquid tank, and the outlet of the primary cooler (26) is connected to the MVR concentration system.

8. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1 is characterized in that: The titanium dioxide material entering the steam mill (1) comes from the flash drying silo.

9. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1 is characterized in that: The first-stage crystallizer (25), the second-stage crystallizer (21) and the third-stage crystallizer (17) are all provided with a liquid level meter, a temperature sensor and a pressure sensor.

10. The steam-powder tail gas waste heat recovery refrigeration coupled DTB crystallization system according to claim 1, characterized in that: The refrigeration unit (10) is a hot water type lithium bromide absorption chiller.

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