Vacuum partitioned drying system and method for high-salinity wastewater

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a high-salinity wastewater vacuum partition drying system and method.The high-salinity wastewater vacuum partition drying system comprises a vacuum drying tank and a stirrer, partition plates are arranged in an inner cavity of the vacuum drying tank at intervals, and the inner cavity of the vacuum drying tank is divided into three drying units in the length direction; the stirrers are differential stirrers, the differential stirrers comprise unit stirrers located in the three drying units respectively, and every two adjacent unit stirrers are connected through a differential mechanism. The periphery of the vacuum drying tank is sleeved with a steam jacket, an inner cavity of the steam jacket is provided with a flow dividing baffle which divides the inner cavity of the steam jacket into three heating areas in the length direction, and the first heating area and the third heating area are both connected with steam inlet pipes. According to the invention, a partition drying design is adopted, so that the stirring speed, the temperature and the heat transfer condition of each drying area can be independently optimized, the characteristics of high-salinity wastewater in different stages can be more accurately adapted, the drying efficiency is improved, meanwhile, the hardening phenomenon is reduced, and the salting-out crystallization uniformity is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a vacuum zone drying system and method for high-salt wastewater. Background Art

[0002] Wastewater generated during industrial production that has a total salt content of 1% or more is called high-salinity wastewater. This type of wastewater usually contains high concentrations of inorganic ions (such as Cl - 、SO4 2- 、Na + and Ca 2+ At present, the recovery of salt in high-salt wastewater mainly relies on evaporation and crystallization technology, which can be divided into two categories: high-temperature evaporation and crystallization and low-temperature evaporation and crystallization. High-temperature evaporation and crystallization usually causes the water to evaporate rapidly by heating the wastewater to 100°C. However, this high-temperature process may not only destroy the structure of some organic components in the wastewater, but also consume a lot of water and energy during the condensation of high-temperature steam. In contrast, low-temperature evaporation and crystallization operates in a high vacuum environment and can reduce the boiling point of water to below 40°C, which not only helps to maintain the structural integrity of the components in the wastewater, but also greatly reduces the energy consumption during the condensation process.

[0003] In the actual material drying process, the whole process can usually be divided into three stages: the first stage is the rapid evaporation of water, at this time the material changes rapidly from liquid to viscous state, and the convection heat transfer inside the material under vacuum conditions is very significant, so that more than half of the water evaporates rapidly in a short time, and the drying speed increases with the increase of temperature and stirring speed; the second stage is the process of transition from viscous state to solid state, in this stage the material gradually solidifies from viscous state, but due to the gradual weakening of internal convection and the increase of thermal resistance, coupled with the upper and lower plate layers formed in the early stage hindering the drying rate, the evaporation process of water is significantly slowed down. At this time, if the operation is continued at a constant vacuum power, the drying efficiency may be reduced due to the further weakening of convection, so the use of fluctuating temperature control and the reasonable matching of temperature and convection heat transfer conditions will help to achieve higher drying efficiency; the third stage is the solid drying process, and the residual water in the material is gradually removed until the required water content is reached and a stable crystal is formed. The water content in this stage is low, but the drying rate is slower than that in the previous stage, and the drying speed can be further increased by appropriately increasing the drying temperature.

[0004] However, the existing vacuum drying device includes a vacuum drying tank, an inlet and outlet arranged at both ends of the vacuum drying tank, and a condenser for condensing the steam generated during the evaporation of high-salt wastewater. However, the vacuum drying tank adopts a one-stage drying process, which cannot be flexibly adjusted according to the different characteristics of high-salt wastewater in each drying stage, and the steam cannot be effectively utilized and is condensed, resulting in low drying efficiency and high processing costs. Summary of the invention

[0005] In order to overcome the above problems, the present invention provides a vacuum zoning drying system and method for high-salt wastewater. By dividing the vacuum drying tank into multiple drying zones, the temperature, vacuum degree and heat transfer conditions of the high-salt wastewater can be optimized in the three stages of initial concentration, salting out crystallization and final drying, thereby improving the drying efficiency and reducing energy consumption.

[0006] The technical solution of the present invention is as follows: A vacuum partition drying system for high-salinity wastewater, comprising a vacuum drying tank and a stirrer arranged at the center of the vacuum drying tank, wherein the inner cavity of the vacuum drying tank is separated by partitions to divide the inner cavity into three drying units along the length direction; the stirrer is a differential stirrer, and the differential stirrer comprises unit stirrers respectively located in the three drying units, and adjacent unit stirrers are connected by differentials, so that the stirring speeds of the unit stirrers are different; The outer periphery of the vacuum drying tank is provided with a steam jacket, and the inner cavity of the steam jacket is provided with a diversion baffle to divide it into three heating zones along the length direction, wherein the first heating zone and the third heating zone are both connected to a steam inlet pipe.

[0007] In a further solution, the unit agitator includes a central shaft and a shaft shell disposed outside the central shaft and meshing with the central shaft, and a plurality of agitating paddles are installed on the outer periphery of the shaft shell; the shaft shell is connected to a differential.

[0008] In a further embodiment, the drying unit, the unit agitator and the heating zone are arranged in a one-to-one correspondence, that is, the longitudinal center lines of the partition, the diverter baffle and the differential are located on the same horizontal plane; wherein: The input end of the first unit agitator is connected to a servo motor for driving; The gear ratio of the first differential connecting the first unit agitator and the second unit agitator is 1:2-5; The gear ratio of the second differential connecting the second unit agitator and the third unit agitator is 1:2-3.

[0009] In a further solution, a sealing assembly is installed on the periphery of the differential to seal it.

[0010] In a further solution, an axial hole for the differential agitator to pass through is opened in the center of the partition, and a gas check valve for steam to pass through is installed on the top of the partition, so that the steam generated by the high-salt wastewater during the evaporation process flows from the third drying unit and the second drying unit to the first drying unit; a gate for the passage of materials is provided at the bottom of the partition.

[0011] In a further embodiment, a first steam inlet hole and a second steam inlet hole are respectively provided on the side walls of the first heating zone and the third heating zone; and a regulating valve is provided on the steam inlet pipe; The bottom of the steam jacket is provided with a discharge port for discharging excess steam or condensed water.

[0012] In a further embodiment, a plurality of pores are arranged on the diverter baffle, and the ratio of the sum of the surface areas of all the pores to the surface area of ​​the diverter baffle is 0.3 to 0.5.

[0013] In a further solution, a feed assembly is provided on the outside of the vacuum drying tank, and the feed assembly includes a feed tank, and the feed tank is connected to the first drying unit of the vacuum drying tank through a feed pipe; a heat exchange assembly is provided inside the feed tank, the air inlet pipe of the heat exchange assembly is connected to the first drying unit, the air outlet pipe of the heat exchange assembly is connected to the condensation assembly, and the air outlet end of the condensation assembly is connected to a vacuum pump for vacuuming.

[0014] According to a further solution, each of the three drying units is equipped with a moisture meter for detecting the moisture content of the material therein; the third drying unit is provided with a discharge port, on which a discharge valve is installed; a drive device and an electric lock are installed on the gate; and the output end of the moisture meter is respectively connected to the drive device, the electric lock and the discharge valve through a PLC controller.

[0015] Preferably, when the moisture content of the material in the first drying unit reaches 40-60wt%, the gate on the first partition is opened, and the material enters the second drying unit; When the moisture content of the material in the second drying unit reaches 10-20wt%, the gate on the second partition is opened and the material enters the third drying unit; When the moisture content of the material in the third drying unit reaches the expected set value, the discharge valve is opened, the material is discharged, and the drying is completed.

[0016] The second invention object of the present invention is to provide a drying method of the above vacuum zone drying system, comprising the following steps: S1, feeding stage: start the vacuum pump to form negative pressure inside the vacuum drying tank. Under the negative pressure, the high-salt wastewater enters the first drying unit in the vacuum drying tank; S2, start-up stage: the differential agitator works, and the steam inlet pipe is opened at the same time to introduce steam into the first heating zone and the third heating zone in the steam jacket. The steam is evenly distributed through the diversion baffle and enters the second heating zone to heat the high-salt wastewater materials in each unit; S3, first drying stage: the differential agitator drives the agitator to rotate, the high-salt wastewater accelerates the evaporation of water under the stirring action, and the material gradually changes from liquid to viscous state; when the moisture content of the material in the first drying unit is detected to be 40-60wt%, the material is introduced into the second drying unit; S4, second drying stage: the gear ratio of the first differential connecting the first unit agitator and the second unit agitator is set to 1:2-5, the material in the second drying unit is continued to be heated and stirred, and the material is further solidified. When it is detected that the moisture content of the material in the second drying unit reaches 10-20wt%, the material is introduced into the third drying unit; S5, the third drying stage: the gear ratio of the second differential connecting the second unit agitator and the third unit agitator is set to 1:2-3, and when the moisture content of the material in the third drying unit is detected to be no more than 5wt%, the material is discharged from the vacuum drying tank to complete the drying process; S6, steam treatment and condensed water collection stage: The saturated water vapor generated by each drying unit passes through the gas check valve on the top of the partition, from the third drying unit, the second drying unit to the first drying unit, and then exchanges heat with the high-salt wastewater in the feed tank, and finally condenses.

[0017] Compared with the existing technology, the present invention has the following beneficial effects: The present invention adopts a zoned drying design, and the inner cavity of the vacuum drying tank is divided into three drying units along the length direction by a partition, that is, the entire drying process is divided into three stages: concentration, salting out and drying, so that the stirring speed, temperature and heat transfer conditions of each drying area can be independently optimized. Compared with the traditional one-stage drying method, the present invention can more accurately adapt to the characteristics of high-salt wastewater at different stages, improve water evaporation efficiency, effectively reduce drying time, reduce the phenomenon of hardening, and improve the uniformity of salting out crystallization.

[0018] The present invention uses a segmented steam jacket to heat the vacuum drying tank, taking full account of the differences in the characteristics of high-salt wastewater in each drying unit. During heating, the amount of steam entering is adjusted to heat the materials in the first drying unit and the third drying unit respectively, and the heating temperature is controlled. In addition, due to the effect of the diverter baffle, the steam entering the first heating zone and the third heating zone enters the second heating zone through the pores, forming a convective steam flow, and then forming a fluctuating heat transfer temperature in the second drying unit. That is, the present invention sets different temperatures for the drying process. When the material is in a liquid state, the heating temperature is increased to accelerate the rapid evaporation of water; when the material enters the curing stage, the input of heating steam is increased to accelerate the evaporation of water inside the drying material, so that the drying process is carried out under the optimal heat transfer conditions, further improving the drying rate.

[0019] The system also integrates a high-efficiency heat recovery and heat exchange device, and uses the steam generated by the high-salt wastewater during the drying process to preheat the high-salt wastewater to be treated through the heat exchange component in the feed tank, so that its initial temperature is increased, thereby reducing additional heating energy consumption; at the same time, the condensation load of the subsequent condensation component 4 is reduced, and efficient energy utilization is achieved. Therefore, compared with the traditional system, the present invention can effectively reduce the overall energy consumption in the drying process, improve the heat utilization efficiency, and make the treatment of high-salt wastewater more economical and sustainable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 is a side view of the differential speed agitator of the present invention; Figure 3 It is a structural schematic diagram of the differential speed agitator in the present invention; Figure 4 It is a structural schematic diagram of the partition in the present invention; Figure 5 It is a structural schematic diagram of the diversion baffle in the present invention; Figure 6 It is a schematic structural diagram of the steam jacket in the present invention.

[0022] The following are the descriptions of the reference numerals: 1. Vacuum drying tank; 11. Differential agitator, 1101. Central shaft; 1102. Shaft housing; 1103. Differential; 1104. Sealing assembly; 12. Partition; 1201. Check valve; 1202. Gate; 13. Jacket; 1301. Diverter baffle; 1302. Air hole; 14. Steam inlet pipe; 1401. First steam inlet hole; 1402. Second steam inlet hole; 15. Condensate outlet; 16. Moisture analyzer; 17. Discharge valve; 2. Feed assembly; 21. Feed tank; 22. Feed pipe; 3. Heat exchange assembly; 31. Air inlet pipe; 32. Air outlet pipe; 4. Condensation assembly; 41. Condensate collection tank. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. The described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] Embodiment 1: See also Figure 1-6 As shown, a vacuum partition drying system for high-salinity wastewater comprises a vacuum drying tank 1 and an agitator arranged at the center of the vacuum drying tank 1. The inner cavity of the vacuum drying tank 1 is separated by two partitions 12, which divide it into three drying units along the length direction, namely the first drying unit, the second drying unit and the third drying unit; the three drying units form a relatively independent drying chamber, and the high-salinity wastewater passes through the three drying units in turn to complete the evaporation of water to achieve the purpose of drying.

[0026] The structure of the partition 12 is as follows Figure 4As shown, an axial hole for the differential agitator 11 to pass through is provided at the center, and a gas check valve 1201 for steam to pass through is installed on the top of the partition 12. The gas check valve 1201 is a one-way valve that can only allow the steam generated by the high-salt wastewater during the evaporation process to flow from the third drying unit and the second drying unit to the first drying unit; a gate 1202 for the passage of materials is provided at the bottom of the partition 12. In this embodiment, the gate is preferably a fan-shaped structure to facilitate the smooth flow of materials. The dried material in the first drying unit enters the second drying unit through the gate on the first partition, and the dried material in the second drying unit enters the third drying unit through the gate on the second partition, thereby completing the overall drying work, and finally the dried material is discharged.

[0027] In this embodiment, the stirrer is a differential stirrer 11 such as Figure 2 , 3 As shown, the differential agitator 11 includes unit agitators respectively located in three drying units, and adjacent unit agitators are connected by a differential 1103. While transmitting power, the differential 1103 allows the front and rear unit agitators to rotate at different speeds, even if the stirring speeds of the unit agitators are different.

[0028] Specifically, the drying unit, the unit agitator and the heating zone are arranged in a one-to-one correspondence, that is, the partition 12, the diverter baffle 1301 and the longitudinal center line of the differential are located on the same horizontal plane; wherein: The input end of the first unit agitator is connected to a servo motor through a coupling for driving; this connection method can ensure that the torque output by the servo motor is stably transmitted to the differential agitator 11. The speed range of the servo motor is 30 to 60 rpm, which can be adjusted according to the drying process requirements of high-salt wastewater. When the servo motor is running, it drives the first unit agitator in the differential agitator to rotate, and transmits it to the second unit agitator through the first differential for decelerated rotation, and then transmits it to the third unit agitator through the second differential for further decelerated rotation.

[0029] In order to effectively control the drying of high-salt wastewater in each unit, the gear ratio of the first differential connecting the first unit agitator and the second unit agitator is 1:2~5; the gear ratio of the second differential connecting the second unit agitator and the third unit agitator is 1:2~3.

[0030] Since the number of teeth of the driving gear and the driven gear in the differential is inversely proportional to the speed, that is, the gear ratio of the first differential is 1:2-5, the number of teeth of the driving gear is small (for example, 10 teeth), and the number of teeth of the driven gear is large (20-50 teeth), the transmission effect of speed reduction and torque multiplication is achieved through meshing. As a result, the speed of the first unit agitator is 2-5 times that of the second unit agitator. Similarly, the speed of the second unit agitator is 2-3 times that of the third unit agitator. As a result, the stirring speed of the unit agitators in the first drying unit, the second drying unit and the third drying unit is gradually reduced. That is, the unit agitators of different drying units can achieve different speeds. When the differential agitator 11 rotates driven by the servo motor, the unit agitators of each drying unit can run at different speeds through the transmission of the differential 1103 to meet the drying needs of high-salinity wastewater at different stages.

[0031] Specifically, the unit agitator includes a central shaft 1101 and a shaft housing 1102 disposed outside the central shaft 1101 and meshing with each other, and multiple groups of stirring paddles are installed on the outer periphery of the shaft housing 1102; the shaft housing 1102 is connected to the differential 1103 through gears to ensure that the two do not slide relative to each other when transmitting torque, thereby ensuring power transmission. Specifically, the outer surface of the central shaft 1101 is processed with gears of specific specifications, and the inner ring of the shaft housing 1102 is also provided with gears matching therewith, and the two mesh with each other, so when the central shaft 1101 rotates, the shaft housing 1102 is driven to rotate synchronously through the action between the gears, thereby providing stirring power for the stirring paddle installed on the shaft housing 1102.

[0032] In order to prevent foreign matter from entering the working area of ​​the differential 1103 and to avoid leakage of internal lubricating oil, a sealing component 1104, such as a sealing ring, a sealing ring, etc., is provided on the outer periphery of the differential 1103 .

[0033] In another embodiment, the outer periphery of the vacuum drying tank 1 is provided with a steam jacket 13 (such as Figure 6 As shown in FIG. 1 ), the inner cavity of the steam jacket 13 is provided with a flow dividing baffle 1301 to divide it into three heating zones along the length direction, wherein the side walls of the steam jacket 13 located in the first heating zone and the third heating zone are respectively provided with a first steam inlet hole 1401 and a second steam inlet hole 1402; the first steam inlet hole 1401 and the second steam inlet hole 1402 are both connected to the steam inlet pipe 14. A regulating valve is provided on the steam inlet pipe 14 to separately adjust the flow of heating steam entering the first heating zone and the third heating zone to achieve the purpose of controlling the heating temperature.

[0034] That is, in this embodiment, the vacuum drying tank 1 is heated by a segmented steam jacket 13. This design fully considers the differences in the characteristics of high-salt wastewater in each drying unit. During operation, steam enters the first heating zone and the third heating zone from the steam inlet pipe 14 through the first steam inlet hole 1401 and the second steam inlet hole 1402 to heat the materials in the first drying unit and the third drying unit. The amount of steam entering is adjusted by the regulating valve on the steam inlet pipe 14 to control the heating temperature in the first drying unit and the third drying unit. In addition, since the first heating zone, the second heating zone, and the third heating zone are separated by a diverter baffle 1301, and a plurality of air holes 1302 are arranged on the diverter baffle 1301 (see Figure 5 ), guide the steam to be evenly dispersed in the jacket 13, so that the heat can be transferred to the middle part of the jacket 13, ensuring that the high-salt wastewater is evenly heated during the drying process, avoiding local overheating or uneven drying. At the same time, the steam entering the first heating zone and the third heating zone enters the second heating zone through the air holes 1302, that is, forming a convective steam flow, and then forming a fluctuating heat transfer temperature in the second drying unit.

[0035] In order to improve the heat transfer efficiency, the ratio of the sum of the surface areas of all the pores to the surface area of ​​the diversion baffle is preferably 0.3 to 0.5.

[0036] The bottom of the steam jacket 13 is provided with a condensate outlet 15 for discharging excess steam or condensate. In the process of releasing heat, the steam will gradually condense into liquid water. The condensate flows downward under the action of gravity, converges to the bottom of the steam jacket 13 along the diverter baffle 1301, and then is discharged from the steam jacket 13 from the condensate outlet 15 to prevent water accumulation from affecting the heating efficiency and the normal circulation of steam.

[0037] In this embodiment, a feed component 2 is provided on the outside of the vacuum drying tank 1, and the feed component 2 includes a feed tank 21 for high-salt wastewater, and the feed tank 21 is connected to the first drying unit of the vacuum drying tank 1 through a feed pipe 22; a heat exchange component 3 is provided inside the feed tank 21, and the air inlet pipe 31 of the heat exchange component 3 is connected to the first drying unit, and the air outlet pipe 32 of the heat exchange component 3 is connected to the condensation component 4, and the air outlet end of the condensation component 4 is connected to a vacuum pump for vacuuming.

[0038] When the vacuum drying tank 1 generates steam during the drying process, the steam flows from the gas check valve 1201 on the partition 12 along the third drying unit, the second drying unit, and the first drying unit, and then enters the heat exchange component 3 from the air inlet pipe 31 for heat exchange, and then enters the condensation component 4 from the air outlet pipe 32. The air outlet of the condensation component 4 is connected to a vacuum pump (not shown in the figure) to evacuate the system, so as to maintain the negative pressure environment of the entire drying system, ensuring that the steam can continue to flow between the components and be condensed. At the same time, the feed pipe 22 uses the negative pressure condition to realize automatic feeding. Specifically, when negative pressure is formed inside the vacuum drying tank 1, the external atmospheric pressure and the pressure inside the tank form a pressure difference. Under the action of this pressure difference, the material (high-salt wastewater) is automatically sucked into the first drying unit in the vacuum drying tank 1 through the feed pipe 22, and no additional power equipment is required to drive the feeding, simplifying the feeding process.

[0039] In this process, the steam generated in the vacuum drying tank 1 enters the heat exchange component 3 located in the feed tank 21, and the heat of the steam is used to preheat the high-salt wastewater in the feed tank 21, while reducing the condensation load of the subsequent condensation component 4, thereby achieving efficient use of energy.

[0040] The heat exchange component 3 adopts a multi-layer folding condenser design, which can greatly increase the heat exchange area and improve the heat exchange efficiency. A condensate collection tank 41 is provided between the heat exchange component 3 and the condensation component 4, and the condensate collection tank 41 is connected to the heat exchange component 3 and the condensation component 4, respectively, for collecting the condensate generated during the evaporation process. When the steam generated in the vacuum drying tank 1 enters the heat exchange component 3, the heat in the steam is transferred to the high-salt wastewater in the feed tank 21, and its own temperature decreases and begins to condense. Under the action of negative pressure, these condensate flows into the condensate collection tank 41 along the pipeline. A pipeline connected to the condensate collection tank 41 is provided at the bottom of the condensation component 4. The condensate generated by the condensation component 4 also flows to the condensate collection tank 41 under negative pressure.

[0041] The gate 1202 and the discharge valve 17 can be opened and closed manually. In another embodiment, in order to enable the gate 1202 and the discharge valve 17 to realize the function of automatic opening, a moisture meter 16 for detecting the moisture content of the material is installed in each of the three drying units, wherein the third drying unit is provided with a discharge port, and the discharge valve 17 is installed on the discharge port; a driving device and an electric lock are installed on the gate 1202; the output end of the moisture meter 16 is respectively connected to the driving device, the electric lock, and the discharge valve through a PLC controller to control their actions.

[0042] The driving device in this embodiment can be selected as a cylinder, a hydraulic cylinder or a linear motor, etc., and its power signal input end is connected to the PLC controller; the electric lock is used to close and lock the gate 1202, and its power signal input end is connected to the PLC controller, and its opening and closing are controlled by the PLC controller; the discharge valve 17 is a solenoid valve, and its power signal input end is connected to the PLC controller. PLC controllers and electric locks are commonly used in the field. This embodiment only selects suitable functions for use, and does not involve improvements in their internal structure, principles, etc.

[0043] That is, when the drying degree of the material in the first or second drying unit reaches the preset value, the moisture meter 16 transmits a signal to the PLC controller, and the PLC controller controls the drive device and the electric lock to work simultaneously, the electric lock opens, the drive device drives the gate 1202 to open, and the dried material enters the next drying unit to continue drying until the end. When the drying degree of the material in the third drying unit reaches the preset value, the moisture meter 16 transmits a signal to the PLC controller, and the PLC controller controls the discharge valve 17 to operate and open the discharge port to discharge the dried material.

[0044] Specifically, when the moisture content of the material in the first drying unit reaches 40-60wt%, the gate on the first partition is opened, and the material enters the second drying unit; When the moisture content of the material in the second drying unit reaches 10-20wt%, the gate on the second partition is opened and the material enters the third drying unit; When the moisture content of the material in the third drying unit reaches the expected set value, the discharge valve is opened, the material is discharged, and the drying is completed.

[0045] Embodiment 2: The drying method using the above vacuum zone drying system comprises the following steps: S1, feeding stage: start the vacuum pump to form negative pressure inside the vacuum drying tank. Under the negative pressure, the high-salt wastewater enters the feeding tank and then automatically enters the first drying unit in the vacuum drying tank through the feeding pipe; S2, start-up stage: the differential agitator works, and the steam inlet pipe is opened at the same time to introduce steam into the first heating zone and the third heating zone in the steam jacket. The steam is evenly distributed through the diversion baffle and enters the second heating zone to heat the high-salt wastewater materials in each unit; S3, first drying stage: the differential agitator drives the agitator to rotate, the high-salt wastewater accelerates the evaporation of water under the stirring action, and the material gradually changes from liquid to viscous state; when the moisture content of the material in the first drying unit is detected to be 40-60wt%, the material is introduced into the second drying unit; S4, second drying stage: the gear ratio of the first differential connecting the first unit agitator and the second unit agitator is set to 1:2-5, the material in the second drying unit is continued to be heated and stirred, and the material is further solidified. When it is detected that the moisture content of the material in the second drying unit reaches 10-20wt%, the material is introduced into the third drying unit; S5, the third drying stage: the gear ratio of the second differential connecting the second unit agitator and the third unit agitator is set to 1:2-3, and when the moisture content of the material in the third drying unit is detected to be no more than 5wt%, the material is discharged from the vacuum drying tank to complete the drying process; S6, steam treatment and condensed water collection stage: The saturated water vapor generated by each drying unit passes through the gas check valve on the top of the partition, from the third drying unit, the second drying unit to the first drying unit, and then exchanges heat with the high-salt wastewater in the feed tank, and finally condenses.

[0046] Embodiment 3: Feeding stage: start the vacuum pump to form negative pressure inside the vacuum drying tank 1. Under the negative pressure, the high-salt wastewater enters the feeding tank 21 and then automatically enters the first drying unit in the vacuum drying tank 1 through the feeding pipe 22. The steam generated by the vacuum drying tank 1 during the heating process will enter the heat exchange component 3 located in the feeding tank 21. The steam heat is transferred to the high-salt wastewater, causing its temperature to rise and the steam itself to condense. The first drying stage: the servo motor is started, and the speed is set to 40 rpm. The regulating valve on the steam inlet pipe 14 is opened and adjusted. The steam enters the first heating zone and the third heating zone in the steam jacket 13 respectively. The steam is evenly distributed through the pores on the diverter baffle 1301 and enters the second heating zone to heat the high-salt wastewater materials in each unit. The differential agitator 11 drives the stirring paddle to rotate, and the high-salt wastewater accelerates the evaporation of water under the stirring action. As the drying process proceeds, the material gradually changes from a liquid state to a viscous state; when the moisture meter 16 detects that the moisture content of the material reaches 40wt%, the PLC controller receives a signal and opens the gate 1202 on the first partition. The material in the first drying unit enters the second drying unit under the push of the stirring paddle; Second drying stage: the gear ratio of the first differential connecting the first unit agitator and the second unit agitator is set to 1:2, the central axis speed of the second unit agitator in the second drying unit changes relative to the first unit agitator to adapt to the drying requirements of the material at this stage, and the material is further solidified and the water evaporation rate is reduced. When the moisture meter 16 detects that the moisture content of the material in the second drying unit reaches 15wt%, the PLC controller opens the gate 1202 on the second partition, and the material enters the third drying unit; The third drying stage: the gear ratio of the second differential connecting the second unit agitator and the third unit agitator is 1:2. On the basis of stirring, the residual moisture in the material is gradually removed. When the moisture content of the material reaches the expected set value (such as 5wt%), the material is pushed by the stirring paddle and discharged from the vacuum drying tank 1 through the discharge valve 17 to complete the drying process; Steam treatment and condensed water collection stage: The saturated water vapor generated by each drying unit passes through the gas check valve 1201 on the top of the partition 12, from the third drying unit, the second drying unit to the first drying unit, and finally enters the heat exchange component 3. After the steam exchanges heat with the high-salt wastewater in the feed tank 21, it enters the condensation component 4. The condensation component 4 condenses the steam into water. The condensed water generated by the heat exchange component 3 and the condensation component 4 flows into the condensed water collection tank 41. The collected condensed water can be subsequently treated or recycled.

[0047] The above is a schematic description of the present invention and its implementation mode, which is not restrictive and is only one of the implementation modes of the present invention, and is not actually limited thereto. Therefore, if a person skilled in the art is inspired by it and, without departing from the purpose of the invention, designs a structure and an implementation mode similar to the technical solution without creativity, they shall all fall within the protection scope of the present invention.

Claims

1. A vacuum zone drying system for high-salinity wastewater, comprising a vacuum drying tank and an agitator arranged at the center of the vacuum drying tank, characterized in that: The inner cavity of the vacuum drying tank is separated by partitions to divide it into three drying units along the length direction; the agitator is a differential agitator, and the differential agitator includes unit agitators respectively located in the three drying units, and adjacent unit agitators are connected by differentials, so that the stirring speeds of the unit agitators are different; The outer periphery of the vacuum drying tank is provided with a steam jacket, and the inner cavity of the steam jacket is provided with a diversion baffle to divide it into three heating zones along the length direction, wherein the first heating zone and the third heating zone are both connected to a steam inlet pipe.

2. A vacuum zone drying system for high-salinity wastewater according to claim 1, characterized in that: The unit agitator comprises a central shaft and a shaft shell arranged outside the central shaft and meshing with the central shaft, and a plurality of groups of agitating paddles are installed on the outer periphery of the shaft shell; the shaft shell is connected to a differential.

3. The vacuum zone drying system for high-salinity wastewater according to claim 1 is characterized in that: The drying unit, the unit agitator and the heating zone are arranged in one-to-one correspondence; wherein: The input end of the first unit agitator is connected to a servo motor for driving; The gear ratio of the first differential connecting the first unit agitator and the second unit agitator is 1:2-5; The gear ratio of the second differential connecting the second unit agitator and the third unit agitator is 1:2-3.

4. The vacuum zone drying system for high-salinity wastewater according to claim 1 is characterized in that: A sealing assembly is installed on the outer periphery of the differential to seal it.

5. The vacuum zone drying system for high-salinity wastewater according to claim 1 is characterized in that: A gas check valve for steam to pass through is installed on the top of the partition, so that the steam generated by the high-salt wastewater during evaporation flows from the third drying unit and the second drying unit to the first drying unit; a gate for material to pass through is provided at the bottom of the partition.

6. The vacuum zone drying system for high-salinity wastewater according to claim 1 is characterized in that: A first steam inlet hole and a second steam inlet hole are respectively provided on the side walls of the first heating zone and the third heating zone; a regulating valve is provided on the steam inlet pipe; A condensed water outlet is provided at the bottom of the steam jacket.

7. The vacuum zone drying system for high-salinity wastewater according to claim 1 is characterized in that: The diverter baffle is provided with a plurality of pores, and the ratio of the sum of the surface areas of all the pores to the surface area of ​​the diverter baffle is 0.3-0.

5.

8. The vacuum zone drying system for high-salinity wastewater according to claim 1 is characterized in that: A feed assembly is provided on the outside of the vacuum drying tank, and the feed assembly includes a feed tank, and the feed tank is connected to the first drying unit of the vacuum drying tank through a feed pipe; a heat exchange assembly is provided inside the feed tank, and the air inlet pipe of the heat exchange assembly is connected to the first drying unit, and the air outlet pipe of the heat exchange assembly is connected to the condensation assembly, and the air outlet end of the condensation assembly is connected to a vacuum pump for vacuuming.

9. The vacuum zone drying system for high-salinity wastewater according to claim 5, characterized in that: The three drying units are all equipped with a moisture meter for detecting the moisture content of the materials therein. The third drying unit is provided with a discharge port, on which a discharge valve is installed; a driving device and an electric lock are installed on the gate; the output end of the moisture meter is respectively connected to the driving device, the electric lock and the discharge valve through a PLC controller.

10. A drying method for a vacuum zone drying system for high-salinity wastewater according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, feeding stage: start the vacuum pump to form negative pressure inside the vacuum drying tank. Under the negative pressure, the high-salt wastewater enters the first drying unit in the vacuum drying tank; S2, start-up stage: the differential agitator works, and the steam inlet pipe is opened at the same time to introduce steam into the first heating zone and the third heating zone in the steam jacket. The steam is evenly distributed through the diversion baffle and enters the second heating zone to heat the high-salt wastewater materials in each unit; S3, first drying stage: the differential agitator drives the agitator to rotate, the high-salt wastewater accelerates the evaporation of water under the stirring action, and the material gradually changes from liquid to viscous state; when the moisture content of the material in the first drying unit is detected to be 40-60wt%, the material is introduced into the second drying unit; S4, second drying stage: the gear ratio of the first differential connecting the first unit agitator and the second unit agitator is set to 1:2-5, the material in the second drying unit is continued to be heated and stirred, and the material is further solidified. When it is detected that the moisture content of the material in the second drying unit reaches 10-20wt%, the material is introduced into the third drying unit; S5, the third drying stage: the gear ratio of the second differential connecting the second unit agitator and the third unit agitator is set to 1:2-3, and when the moisture content of the material in the third drying unit is detected to be no more than 5wt%, the material is discharged from the vacuum drying tank to complete the drying process; S6, steam treatment and condensed water collection stage: The saturated water vapor generated by each drying unit passes through the gas check valve on the top of the partition, from the third drying unit, the second drying unit to the first drying unit, and then exchanges heat with the high-salt wastewater in the feed tank, and finally condenses.

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